IPAC'26 - the 17th International Particle Accelerator Conference

17 May 2026, 09:00 → 22 May 2026, 18:00 Europe/Zurich

C.I.D

Hanna Franberg Delahaye (Grand Accélérateur National d'Ions Lourds), Peter McIntosh (Science and Technology Facilities Council), Rogelio Tomas (European Organization for Nuclear Research)

Sunday 17 May

09:30 → 10:30 Duties for students with Grants

Student_Duties_Sunday.pdf

Student_Duties_Sunday.pptx

14:00 → 18:00 Registration on site

14:00 → 18:00 Student poster session

14:00 A bayesian optimization study of the longitudinal localized excitation slow extraction for the XiPAF-Upgrading Synchrotron

The longitudinal localized excitation slow extraction method reduces the energy spread of the extracted beam by applying transverse excitation exclusively within specific phase intervals at the edges of the longitudinal phase space of the bunch. For localized square-wave excitation, conventional amplitude modulation formula struggles to achieve uniform beam spill, while the temporal uniformity of the extracted beam is crucial in radiotherapy and related physics experiments.
The XiPAF-Upgrading Synchrotron (with a circumference of 39.96 m), developed from Xi’an 200 MeV Proton Application Facility, serves as a dedicated platform for the study and evaluation of single-event effects on core electronics for astronautics. We simulated the localized square-wave excitation slow extraction process using the SynTrack particle tracking code based on the XiPAF-Upgrading Synchrotron's parameters to extract low energy spread beam. Furthermore, a Bayesian optimization method was employed to refine the amplitude modulation curve of the excitation signa, thereby achieving highly uniform beam spill under low-energy slow extraction conditions.

Speaker: Chuhao Li (Tsinghua University)

14:00 A Boundary Element And Fast Multiple Method For Electron Cloud Field Computation

Electron cloud build-up simulations rely on accurate self-consistent electric field computation to correctly model the secondary emission cascade. The PyECLOUD code solves this via a Particle-in-Cell (PIC) approach using the Shortley-Weller finite-difference (SW-FD) Poisson solver. This work presents a Boundary Element Method (BEM) formulation for the electrostatic space-charge field that discretizes only the chamber wall into panels and evaluates particle forces via direct Coulomb summation, entirely avoiding volumetric grids. The BEM solver is validated against the analytic image solution for a circular chamber (error $<0.2\%$) and cross-validated with the existing SW-FD solver on the LHC Arc-Dipole chamber, showing sub-percent agreement over the chamber interior. The BEM module is integrated into the PyECLOUD simulation pipeline as a plug-in field solver. Build-up simulations comparing BEM ($N=50$ and $N=200$ panels) with the baseline PIC solver (0.3~mm grid) produce consistent electron cloud line densities, confirming that the BEM formulation correctly captures the physics of the original solver. The BEM panels simultaneously provide a unified geometry for impact detection and secondary emission. The Fast Multipole Method is introduced to accelerate the intrinsic $\mathcal{O}(N^2)$ particle-particle Coulomb sum, and GPU acceleration is proposed as a path toward a standalone BEM-FMM code scalable to $>10^5$ particles.

Speaker: Siyuan Feng (University of Chinese Academy of Sciences)

14:00 A computational methodology for the efficient Ac-225 production via proton irradiation of Ra-226

Ac-225 is a crucial isotope for targeted alpha therapy, yet its clinical application is severely constrained by supply shortages. The use of high-intensity proton beams from linear accelerators to irradiate Ra-226 targets offers a viable approach to significantly enhance Ac-225 production. However, excessive proton energies, while increasing yield, promote the generation of impurity isotopes such as Ac-227, complicating chemical separation and raising both production costs and radiological concerns.This study employs Geant4 Monte Carlo simulations with a detailed model that includes the beam window, target, and encapsulation structure. By systematically simulating nuclear reactions across various energy levels, we quantified the production yields of Ac-225 and its impurities. An optimal proton energy was identified that maximizes Ac-225 yield while effectively controlling impurity levels, providing key insights for efficient large-scale Ac-225 production.

Speaker: XinYa Sun (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

14:00 A low cost picoseconds precision timing and synchronization over a kilometer

Large-scale accelerators, including colliders and accelerator-based light sources, require synchronization and time distribution over distances of several tens of kilometers. Precisions of femtoseconds have been demonstrated, but the systems used to reach such specifications are costly and difficult to integrate in a particle accelerator environment. Applications such as bunch-per-bunch position monitoring and Compton polarimetry require picosecond timing and precision and often meet tight integration requirements. This is particularly true for the latter, where a passively mode-lock laser must be integrated in the accelerator environment, with 10 to 100km scale. We propose to implement a system exploiting a White Rabbit protocol-based frequency generation system, the Idrogen. We demonstrate the proof-of-concept of synchronization of a pulsed laser with a few hundred megahertz repetition rate with picosecond jitter precision through a kilometer-long optical fiber. Drifts of a few picoseconds were observed, related to environmental changes. Prospects for improvements will be exposed.

Speaker: Alice Renaux (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

14:00 A modular optimization framework for 4th generation light source lattice design: synergizing physics priors and statistical learning

The design of fourth-generation synchrotron light sources based on Hybrid Multi-Bend Achromat (H-MBA) structures faces significant challenges due to the high dimensionality of design variables and the strong nonlinear effects induced by strong focusing forces. The traditional paradigm of manual matching followed by stepwise fine-tuning'' encounters bottlenecks in optimization efficiency and physical interpretability. This paper proposes a modular optimization framework that fuses physics priors with statistical learning to achieve synergistic optimization of linear optics and nonlinear dynamics. The framework uses Twiss parameter evolution as an intermediate physical representation, and a physics-prior screening mechanism driven by linear transport is combined with the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). This approach identifies stable periodic solutions with reduced natural emittance within minutes and shows reproducible efficiency gains over manual initializations. Machine-learning classifiers trained on the generated dataset perform high-confidence pruning of the solution space and retain high-quality solutions. A local trust region constructed around thesepromising solutions'' introduces the Sequential Model-based Algorithm Configuration (SMAC) strategy based on Random Forests for refined iteration. This method provides an efficient and intelligent pathway for complex, high-dimensional lattice design.

Speakers: LINGLONG MAO (Shanghai Institute of Applied Physics, Chinese Academy of Sciences), Shunqiang Tian (Shanghai Advanced Research Institute, Chinese Academy of Sciences), Xinzhong Liu (Shanghai Advanced Research Institute), Liyuan Tan (Shanghai Advanced Research Institute, Chinese Academy of Sciences), Yihao Gong (Shanghai Synchrotron Radiation Facility)

14:00 A novel approach for transverse instability detection in the CERN Proton Synchrotron

The CERN Proton Synchrotron faces increasingly demanding requirements from its user community, driven by the need for higher-intensity beams that push the machine to the limits of beam stability. Transverse instabilities, such as head-tail and transverse-mode-coupling instabilities, can arise at specific stages of the machine cycles, depending on the beam parameters. This work introduces a real-time, bunch-by-bunch transverse instability diagnostic system based on wide-band beam position monitor signals. Building on recent developments in longitudinal beam observation, the system extends the software layers to measure beam profiles in both longitudinal and transverse planes. A key feature is its ability to capture multiple time windows within a single cycle, offering a complete view of beam dynamics. Real-time analysis of the transverse beam envelope evolution is performed on the acquired data to detect and characterize performance-limiting phenomena, such as transverse instabilities. The system is fully integrated into operation, allowing simultaneous beam monitoring and optimization across multiple beam types.

Speaker: Amaury Beeckman (European Organization for Nuclear Research)

14:00 A novel method for measuring the energy spectrum of an inverse Compton scattering source based on nuclear resonance fluorescence

We proposed a novel method of using nuclear resonance fluorescence (NRF) as a probe for spectrum measurements. By utilizing the continuous tunability of an ICS source, NRF photons can be excited at different points across the spectrum. The shape of the energy spectrum can then be effectively scanned and reconstructed by recording the relative NRF yields at different energy points. The feasibility of the proposed method was validated by Geant4 simulations of measuring NRF photon emission from 56Fe irradiated by an ICS source. The simulation results showed high precision for quasi-monochromatic gamma ray spectrum measurements, with a normalized root mean square error (NRMSE) of less than 5%. To maintain a sufficient signal-to-noise ratio (SNR) during the measurement, the energy resolution of detectors is suggested to be less than 1% of the energy being measured. Given an energy tuning precision of Delta E, the minimum measurable width of the energy spectrum, in terms of standard deviation, can reach 0.85 Delta E.

Speaker: Jin Lin (Tsinghua University)

14:00 A study of beam loss data analysis for the high energy photon source

The High Energy Photon Source(HEPS) is China's first and world-leading fourth-generation high performance synchrotron radiation light source. To meet beam commissioning requirements and better monitor the beam status of HEPS, a beam loss measurement(BLM) system based on scintillator detectors has been designed and installed. We conducted a quantitative analysis of beam loss data using neural networks that integrated the BLM system with the beam current measurement system, which achieved an accuracy close to 90%.This approach assists in beam loss diagnosis, helps optimize factors contributing to beam loss, reduces potential damage to superconducting cavities and sensitive components, and ensures the stable operation of the machine.

Speaker: junjie ren (Institute of High Energy Physics)

14:00 A visible-light monitor for transverse beam profile diagnostics in the SLS booster

A visible-light 2D imaging monitor was developed and commissioned in the Swiss Light Source (SLS) 2.0 booster ring to characterize transverse beam behavior during the energy ramp. Installed downstream of a bending magnet, it extracts visible synchrotron radiation via an in-vacuum gold-coated mirror and uses a CMOS camera with motorized optics and filters. The setup accommodates the evolving synchrotron spectrum, with the critical photon energy increasing from 0.2 eV at 100 MeV electron beam energy to approximately 3.9 keV at 2.7 GeV. Long exposures, integrating over hundreds of turns matched to the roughly 1 µs revolution time, enabled measurements of adiabatic damping due to synchrotron radiation emission. In addition, the system provides sufficient sensitivity to image single-bunch charges down to approximately 20 pC, while operating over a broad charge range up to 300 pC. Using short exposures over only a few tens of turns enabled the observation of fast beam size evolution during emittance exchange driven by coupling resonance crossing, a technique first implemented in an electron ring at the SLS*. This high-speed acquisition confirmed the optimal extraction timing, corresponding to the minimum horizontal beam size. The monitor provides non-invasive diagnostics for tracking beam stability and optimizing injection into the storage ring.

Speaker: Maria Paula Rey Barrera (Paul Scherrer Institute)

14:00 Acceleration gradients in dielectric laser accelerators with single and double triangular-shaped gratings

The acceleration of electrons in dielectric laser accelerators (DLAs) with a triangular ridge profile on the structure's surface was investigated. The aim was to to determine the maximum acceleration gradients when using DLA with triangular profiles. Single chip structures with a triangular profile, both transparent and reflective to laser radiation, were considered. The acceleration gradients were found as a function of the base angle of the grating ridge. Left-handed and right-handed variations of these triangular structures, differing in the ridge tilt direction, were also examined. Electron acceleration using double-triangular structures, consisting of various combinations of transparent and opaque structures, was also conducted. The maximum values of energy gain and acceleration gradients for all investigated combinations of single and double chip structures were determined and quantified. The effect of the longitudinal displacement of one structure relative to the other in a double configuration on the change in energy gain and acceleration rate was also studied. Based on the obtained results, it can be stated that in DLAs with a triangular profile, acceleration rates can reach 400 MeV/m.
This study is supported by the National Research Foundation of Ukraine under the program “Excellent Science in Ukraine” (project # 2023.03/0182).

Speaker: Oleh Svystunov (National Science Center Kharkiv Institute of Physics and Technology)

14:00 Accelerator performance drift compensation with a modified MG-GPO Algorithm

Performance drift has been a longstanding problem for accelerators. A desirable solution is to tune the machine slowly and gently to compensate for such drift. Previously, we presented a version of the Multi-Generation Gaussian Process Optimizer which tunes accelerator settings during operation to maintain optimal performance. In this paper, we present an improved version of the algorithm and its application test examples, in which it corrects deviations from the ideal orbit caused by a drifting orbit corrector magnet and a drifting injection kicker magnet respectively. The modified algorithm takes measures to ensure the accuracy of the Gaussian process regression models and to improve the validity of the new trial solutions. We demonstrate that this is a promising development toward using safe, real-time tuning algorithms during accelerator programs to compensate for performance drift.

Speaker: Ryan Yeung (Michigan State University)

14:00 Accelerator-driven radiation studies of YSZ-MgO composites for nuclear applications

Particle accelerators and synchrotron radiation facilities are pivotal tools in advancing nuclear materials research. In this study, we harnessed accelerator-driven ion beams and synchrotron-based spectroscopies to investigate the radiation tolerance of ceramic composites as candidates for Inert Matrix Fuel (IMF). Yttria-stabilized zirconia (YSZ) stands out as a potential material for IMF due to its high radiation tolerance, low neutron cross-section, compatibility with fissile materials, etc. However, its relatively low thermal conductivity is a significant limitation. To address this, we developed a composite of YSZ with a material of high thermal conductivity, viz., MgO. The YSZ-MgO composites were irradiated using 400 keV Kr and 80 MeV I ions at both ambient and reactor-relevant temperatures, employing ion accelerators to simulate radiation encountered in reactors. YSZ-MgO composites exhibit superior resistance to radiation-induced structural degradation compared to single-component YSZ. Samples irradiated at elevated temperature demonstrated enhanced radiation resistance compared to room temperature irradiated samples. Notably, a distinct radiation response emerges when magnesium is doped into the YSZ lattice rather than forming a separate MgO phase. Insights from synchrotron-based XPS, XAS and thermal spike simulations will be discussed to elucidate the mechanisms governing the enhanced radiation tolerance of ceramic composites.

Speaker: Rishvana Parveen (University of Petroleum and Energy Studies)

14:00 Active supervision for AGS bunch-merging with LLM-based reinforcement learning

Radio-frequency (RF) bunch-merging gymnastics is used in the RHIC heavy-ion program to combine individual source pulses into single bunches with suitable intensity. To preserve both intensity and emittance during these gymnastics, the voltages and phases of RF cavities at several harmonic numbers must be carefully coordinated, which is labor-intensive and fragile. Recent work using a physics-based simulator of the Brookhaven Alternating Gradient Synchrotron (AGS) has shown that reinforcement learning (RL) can learn effective merge configurations. However, RL is highly data-intensive and requires many training interactions with the environment. Recent advances in large language models (LLMs) have demonstrated their capability of extracting patterns from large, noisy data. In addition, LLM is able to integrate domain knowledge in the control loop to improve sample efficiency and improve robustness. Therefore, it is an attractive solution for tuning complex accelerator systems. However, domain adaptation (i.e., prompt engineering, finetuning, etc.) is always required for deploying LLM in the target domain and has not been investigated in particle accelerators. To fill this gap, we propose an active supervision framework in which the LLM-based teacher first transfers general control principles from human operators to the student agent. Then, the student agent further finetunes the control policy by interacting with the simulator/experiments with improved sample efficiency.

Speakers: Yinan Wang (Rensselaer Polytechnic Institute), Mr Yue Zhao (Rensselaer Polytechnic Institute)

14:00 Advances in large-scale non-evaporable getter coating techniques for the Hefei Advanced Light Facility

The Hefei Advanced Light Facility (HALF), currently under construction, is a fourth-generation synchrotron radiation source operating in the low-energy region (2.2 GeV) and based on diffraction-limited storage ring technology. The storage ring employs a modified hybrid 6BA lattice with a beam emittance of 86.3 pm·rad and consists of 20 achromat cells with a total circumference of approximately 480 meters. To meet the ultra-high vacuum environment of the storage ring, non-evaporable getter (NEG) films are applied to the inner surfaces of the vacuum chambers to provide distributed pumping capability and to reduce surface outgassing and photon-stimulated desorption. Large-scale NEG coating of the HALF storage ring vacuum chambers has been officially initiated. This paper presents an overview of the HALF storage ring vacuum system and provides a systematic description of the large-scale NEG coating system, including the equipment configuration and control system. In addition, a storage system for coated vacuum chambers is described to ensure film quality prior to installation, which provides technical support for subsequent assembly and commissioning.

Speaker: Xiaopeng Xu (University of Science and Technology of China)

14:00 AI and machine learning techniques for LNL accelerators

The application of Artificial Intelligence (AI) and Machine Learning (ML) to particle accelerator systems has emerged as an effective strategy for managing complex operations and enhancing performance. At INFN-Legnaro National Laboratories (INFN-LNL), both offline and online AI/ML-driven approaches have been developed to improve beam dynamics, reduce setup times, and increase overall accelerator efficiency.

Offline efforts focus on surrogate modeling of complex facilities such as ANTHEM BNCT, as well as on virtual diagnostics implemented using supervised neural operators. By combining these tools with AI/ML optimization algorithms, new design and commissioning strategies are being explored to further enhance beam quality and operational performance.

In parallel, online real-time optimization strategies based on Bayesian Optimization (BO) has delivered promising results. Notably, at the PIAVE-ALPI superconducting accelerator, the application of BO improved beam transmission up to 85%, a significant increase compared to the typical operational average of 35%. These advances demonstrate the growing impact and future potential of AI/ML technologies in accelerator science and operations.

Speaker: Ysabella Kassandra Ong (Istituto Nazionale di Fisica Nucleare)

14:00 AI-based diagnostics for the cryogenic and RF systems of the SPIRAL2 superconducting LINAC

The SPIRAL2 superconducting LINAC at GANIL operates 26 quarter-wave resonator cavities whose online diagnostics currently rely on physics-based models limited to single operating points. This paper presents two complementary AI-based diagnostic tools: (i) neural-network heat-load virtual observers that estimate the cavity thermal dissipation — a proxy for the intrinsic quality factor Q0 — from cryogenic process signals, with prediction errors predominantly in [−2, +1] W@4.2 K for loads up to 20 W@4.2 K; and (ii) a machine-learning pipeline meant to detecting anomalies in LLRF data, predicting alarms before they fire, and classifying fault subtypes within the cavity-quench category ($F_1$ = 92%). This paper presents a state of progress on these two applications.

Speaker: Charly Lassalle (Grand Accélérateur National d'Ions Lourds, Université de Caen Normandie)

14:00 Alignment error analysis based on HALF lattice

The storage ring of the Hefei Advanced Light Facility has a circumference of approximately 480 m and consists of 20 hybrid six-bend achromatic (H6BA) lattice units with a natural emissivity of approximately 86 pm·rad. High-brightness diffraction-limited light sources place higher demands on alignment. This paper focuses on the HALF lattice and uses the Accelerator Toolbox (AT) utility program for high-fidelity error analysis and calibration simulation. Sensitivity assessments for different error sources are presented, and the optical degradation laws under overall beam misalignment and superposition states are investigated. The usability boundary under uncorrected conditions is also given.

Speaker: qiuyu zhang (University of Science and Technology of China)

14:00 Analog down-conversion and digital readout system for a cavity BPM beam tested at ATF

A complete analog readout system designed to extract reference and position signals from a single cavity Beam Position Monitor (cBPM) has been developed for a proto type from CEA Saclay. The complete system underwent beam testing at the Accelerator Test Facility (ATF). The monitor operates with a dipole mode centered at 1.725 GHz, requiring translation to lower frequencies for digitization and subsequent signal processing via a digital-down-conversion (DDC) algorithm. Throughout beam campaigns in May, June, and December 2025, various synchronized local oscil lator (LO) configurations and down-conversion architectures were evaluated. The final optimized systems achieved intermediate fre quencies (IF) of 417 MHz, 297 MHz, and 60 MHz. Through iterative enhancements in synchronization, filtering, and hardware integration, a peak vertical resolution of 2.81 µm was demonstrated.

Speaker: Juan Carlos Fernández Ortega (Instituto de Física Corpuscular)

14:00 Analysis and research on measurement errors caused by magnet misalignment in energy analysis systems

Accurate evaluation of the beam energy and energy spread plays a crucial role in the commissioning and operation of electron accelerators. The energy analysis (EA) system, consisting of a dipole with associated upstream and downstream drift sections, is widely applied in accelerator facilities due to its structural simplicity, large measurement range, and high resolution. However, assembly errors, leading to offsets or tilt angles between the input beam and the designed system axis, are inevitably introduced during engineering implementation. Such misalignment necessarily affect the accuracy of the measurement results of the EA system, and the impact may be even more significant for low-energy e-beams with the energy of a few MeV. In this context, based on the low-energy injector experimental platform currently under construction, the misalignment induced errors in the dipole-based EA systems are analyzed in depth, and potential compensation methods are explored. The study aims to provide both theoretical support and practical guidance for optimizing system alignment and improving measurement precision.

Speaker: Yan Wang (Huazhong University of Science and Technology)

14:00 Analytic phase-space and spectral modeling of amplitude-dependent resonance island dynamics near the third-integer resonance

We present an analytic phase-space and spectral framework for single-particle dynamics near the third-integer resonance in circular accelerators, emphasizing amplitude-dependent nonlinear effects. Starting from a resonant Hamiltonian in action–angle variables, we derive closed-form relations among island action, separatrix geometry, and the amplitude-dependent tune for both the primary orbit and the resonance islands. Mapping this parameterization into the frequency domain yields analytic predictions for the main spectral line and higher-order sidebands, enabling a quantitative interpretation of fine spectral structures, including tune plateaus (step-like tune locking). Multi-turn tracking with ELEGANT shows good agreement in both phase space and spectra, establishing a rigorous and interpretable basis for analyzing nonlinear resonance effects in Transverse Resonance Island Buckets (TRIBs), RF knock-out, and other resonance-island-based beam operations.

Speaker: Youngmin Park (Pohang University of Science and Technology)

14:00 Application of novel RF direct sampling electronics for SHINE cavity BPM

Shanghai High Repetition Rate XFEL and Extreme Light Facility (SHINE) is a continuous wave superconducting linear accelerator. It is the largest Chinese investment in scientific infrastructure ever. In order to achieve measurement of the electron beam position with a resolution of over 200 nm in the undulator, a new RF direct sampling electronics for the SHINE cavity BPM system was developed, which directly samples the 5.254 GHz cavity BPM signal at 2.6 GSPS with a processing speed of 1 MHz. Compared to traditional electronics, which rely on complex analog down-conversion before digitization, this system greatly simplifies the front-end by removing the need for down-conversion phases and achieving comparable performance. This is the first time that a batch of RF direct sampling electronics for cavity BPMs on a FEL has been introduced. In this paper, we will present the developed and deployment of the RF direct sampling electronics for SHINE cavity BPM.

Speaker: Yuxin Han (Shanghai Institute of Applied Physics)

14:00 Application of the nonlinear optics from off-energy orbits method at the SIRIUS storage ring

The applicability of the Nonlinear Optics from Off-Energy Closed Orbits (NOECO) method to the SIRIUS storage ring is investigated. Off-energy orbit response matrices (OEORMs) were measured and used for sextupole strength calibration through a Levenberg-Marquardt (LM) fitting procedure with Tikhonov regularization. The fitted strengths reproduced the measured chromaticities with reasonable accuracy and were consistent with control system estimates. Analysis of the OEORM Jacobian revealed strong correlations among sextupole family signatures, indicating significant quasi-degeneracies in the inverse problem. Machine experiments and model-based simulations showed that localized perturbations are redistributed across correlated families, especially in the presence of small optics mismatches. The results indicate that OEORM-based calibration is feasible at SIRIUS, although its resolving power is fundamentally limited by parameter correlations and model imperfections.

Speaker: Matheus Velloso (Brazilian Synchrotron Light Laboratory)

14:00 Autoencoder architectures for beam anomaly detection and statistical distribution characterization

In accelerator facilities, the control and assessment of a high-quality beam delivery require capable monitoring systems, including both hardware and software components. In most accelerator beamlines, precise measurements and reliable beam delivery are critical factors in their operation. At the CERN IRRAD facility, the transverse beam profile carries the essential information about the beam properties of interest for materials and component irradiation. Precise measurements and reliable beam delivery are critical factors in its operation.
Building upon the existing IRRAD-BPM (Beam Profile Monitor) instrument at CERN, we explore the possibilities of employing Machine Learning techniques, with special focus on Autoencoder (AE) architectures. Dealing with a critical system that involves high-energy protons and extreme radiation conditions, we developed an AE-based anomaly-detection system. Its architecture, based on multiple parameters, is a result of hyperparameter optimisation aiming for the highest separation of anomalous samples. Additionally, to mitigate the existing limited BPM coverage that cannot capture the full extent of the beam tails, we perform a measurement-space statistical inference using this AE architecture. Moreover, by using a Multi-Wire Proportional Chamber (MWPC) device also present on the IRRAD beamline, we improve the beam profile modelling within a data fusion-like approach.

Speaker: Jaroslaw Szumega (European Organization for Nuclear Research)

14:00 Automated tuning techniques at TRIUMF for the ARIEL era

Implementing automated tuning techniques has been a priority at TRIUMF, driven by the need to support the significant increase in RIB availability expected with the new Advanced Rare Isotope Laboratory (ARIEL). This efficiency boost will facilitate a broad spectrum of research in nuclear, particle, and astrophysics. This work outlines the shift from manual tuning to an automated approach for optimizing beamline transport. We utilize the predictive digital twin, Model Coupled Accelerator Tuning (MCAT), to compute transport and accelerated beam tunes, while Bayesian Optimization for Ion Steering (BOIS) handles beam orbit correction. BOIS treats steering as a black-box optimization problem, maximizing beam current based solely on direct measurement. By combining MCAT and BOIS, this method offers a more efficient, physics-grounded tuning process, with potential applications for facilities beyond TRIUMF.

Speaker: Omar Hassan (TRIUMF, University of Victoria)

14:00 AWAKE Laser Synchronisation and Optical Timing Distribution Network

The Advanced Wakefield Experiment (AWAKE) at CERN demands state-of-the-art timing and synchronisation performance. Upgrades due for completion 2029 require sub-50 fs laser synchronisation from its distributed laser systems to achieve experiment baselines. Accordingly, a time-of-flight stabilised all-optical timing distribution network in development with Lancaster University aims to establish a timing coherence of tens of femtoseconds between sub-systems separated by 100 m. This contribution outlines system architecture, stabilisation strategy and progress to date.

Speaker: Joshua Gregory (Lancaster University)

14:00 Bayesian optimization of longitudinal phase space in the MAX IV linac

Reaching design performance in modern particle accelerators is a challenge involving many tasks which are time-consuming and difficult to perform. It is always an advantage to be able to simplify high-level operational tasks and measurements through the assistance of optimization techniques. In this work we applied Bayesian optimization via the XOpt framework with the aim to simplify and enhance the operations in the MAX IV linac. The focus of this work has been longitudinal phase-space optimization using signals from a transverse deflector system. Further, a new approach in the optimization of longitudinal phase-space parameters with the use of virtual diagnostics has been developed and implemented.

Speaker: Johan Lundquist (Lund University)

14:00 Beam charge diagnostics in laser-plasma accelerators with diamond detectors

Accurate measurement of shot-to-shot fluctuations in electron beams produced by laser-plasma accelerators (LPAs) is important for their development. Reliable monitoring of beam reproducibility and stability is crucial for their operation. However, the very high instantaneous flux of electrons is a major challenge for any radiation diagnostics system. In this work, the characterisation of the beam charge measured using a diamond sensor in an LPA environment is presented. A dedicated diamond detector with shunt readout was installed at the Lund High-Power Laser Facility. The electron beam charge was measured in correlation with the tuned laser and plasma parameters. The measurement results will be discussed and an outlook on the development of beam diagnostics for LPA facilities will be given.

Speaker: Divya Divya (TU Wien)

14:00 Beam Dynamics Studies in the SuperKEKB Linear Accelerator and Beam Transport System

The next luminosity milestone at SuperKEKB requires improved emittance preservation of the injected beams, which remains a key limitation of the injector chain. Although emittance growth in the LINAC and beam-transport (BT) lines has been studied previously, the combined impact of collective effects, lattice imperfections, and other uncertainties is still not fully understood.
A major contributor to the horizontal emittance growth is incoherent and coherent synchrotron radiation (ISR/CSR), particularly evident for the electron BT (BTe). The vertical emittance also increases in this region, though its origin is not yet clear. Additional dilution arises from short-range wakefields and lattice misalignments, which amplify trajectory jitter and generate residual dispersion and coupling. Earlier studies did not systematically include these effects. Moreover, recent magnetic-field measurements of the BTe dipoles indicate non-ideal field profiles, motivating the use of representative field maps in the BT lattice.
This study incorporates wakefields, ISR/CSR, realistic alignment errors, and updated BTe dipole fields within a unified tracking framework to quantify their combined influence on emittance growth. The results clarify the dominant limitations in the current injector and support strategies for achieving stable, low-emittance injection in future high-luminosity operation.

Speaker: Andrea Aguirre Polo (Deutsches Elektronen-Synchrotron DESY)

14:00 Beam Induced Fluorescence experiments for Ultra-High-Dose-Rate dosimetry in proton therapy

Ultra-High-Dose-Rate (UHDR) / FLASH radiotherapy with proton pencil beams requires particle fluxes that saturate current clinical dosimetry, such as ionisation chambers. Before UHDR proton therapy can be clinically implemented, novel dosimetry techniques must be developed that reduce the uncertainty on delivered dose to within clinical accuracies. One promising solution is to image gas Beam Induced Fluorescence (BIF), where the photon yield and transverse profile can be combined to calculate an absolute dose. Using the AGOR cyclotron at PARTREC, a superconducting isochronous cyclotron capable of providing clinical beam energies and dose-rates well into the UHDR regime, we are assessing the feasibility of using BIF for dosimetry. We show that the photon yield of Nitrogen remains linear with dose even at UHDR beam currents and examine the gas pressure-dependence in the range from 1e-3 to 100 mbar. When calculating doses, the width of the fluorescent region is compared to the real transverse beam size and methods to remove the background neutron and gamma counts from the CCD image without significantly altering the photon yield are described. These experiments are the first step towards progressing towards minimally invasive optical beam monitoring with a BIF-based dosimetry device, incorporating both transverse profile and energy deposition measurements, that could be used in proton therapy.

Speaker: Thomas Fogg (Particle Therapy Research Center)

14:00 Beam Misalignment and Current Loss in the Karaj-C30 Cyclotron: Diagnostics and IBSimu Analysis

The 30 MeV Karaj-C30 cyclotron, developed for medical and industrial radioisotope production, accelerates H⁻ ions to 15–30 MeV and D⁻ ions below 15 MeV using a carbon stripper foil for extraction. The system features a filament-based negative hydrogen multicusp ion source providing 1–2 mA, an injection line with optical elements, a two-sector electromagnet, and an RF resonator. Beam profiles measured 30 cm upstream of the stripper magnet using a Mylar foil revealed a significant horizontal shift and beam loss on the injection-line optics. IBSimu simulations of the extraction system reproduced this deflection and indicated that erosion of the ground electrode created a radial electric field responsible for the observed misalignment. Replacing the damaged electrode restored the beam trajectory and recovered the extracted current to 80 μA, in agreement with simulation predictions. Despite the improved alignment, the measured profiles still show signs of non-optimal extraction optics and a perveance mismatch. Future work will focus on redesigning the extraction system to achieve higher transported currents for isotope production.

Speaker: Keyvan Tabaei (University of Isfahan)

14:00 Beamline Optimization for Laser-Accelerated Ions

Laser-plasma acceleration can generate short, intense ion beams with energies up to several hundred MeV. However, the intrinsic large divergence and broad energy spectrum of these beams necessitate dedicated capture and transport beamlines to achieve high particle yields for applications. In this work, we use the LIGHT beamline with the PHELIX laser at GSI as an example case to develop and evaluate methods for optimizing and aligning such beamlines. Our focus is on future applications including injection into conventional accelerators and as a complement to traditional ion sources. Using the UNILAC at GSI as a reference case, we show that, for the present PHELIX laser intensities the number of laser-accelerated protons viable for SIS18 injection remains at least an order of magnitude below the typical bunch intensity of conventional linacs. Finally, by deriving and applying scaling laws for the transmission through the first capture element, we propose strategies for further improvement to bridge this gap in the future.

Speaker: Daniel Dewitt (Technical University of Darmstadt)

14:00 Beta Function Measurements using Quadrupole Variation in SLS 2.0

The Swiss Light Source upgrade, SLS 2.0, is a fourth generation storage ring based on a seven-bend achromat design and is currently under commissioning. Precise knowledge and control of the linear optics are essential for optimal machine performance. This contribution presents measurements of the beta function using the quadrupole variation method at 264 locations around the ring. The corresponding tune shifts were determined with high resolution via the mixed BPM technique combined with Numerical Analysis of Fundamental Frequencies (NAFF).

Speaker: Jesus Avila Pulido (Paul Scherrer Institute)

14:00 Cavity geometry optimization for multipactor suppression in a VHF CW electron gun

VHF CW photocathode electron guns suffer from severe multipactor effects that significantly degrade their operational performance. In this work, the RF cavity geometry was optimized via CST simulations to suppress multipactor, employing a three-phase strategy with fixed key structural parameters. Compared with the SHINE gun baseline, the optimized cavity achieves a much lower multipactor growth rate $\alpha$ while preserving excellent high-performance RF characteristics. This demonstrates that geometry optimization is an effective approach to mitigate multipactor in VHF CW photocathode electron guns.

Speaker: Yitong Duan (Tsinghua University)

14:00 Challenges of Moderate Energy External Injection into Laser-Driven Wakefield Accelerators

Laser Wakefield Acceleration (LWFA) enables GV/m acceleration gradients, promising compact accelerator designs with advantages in cost, environmental impact and portability. Standard LWFA schemes can suffer from poor shot-to-shot stability and beam quality, resulting in broad energy spectrums, beam current variations, high emittance and limited intensity. External injection schemes attempt to overcome such challenges by treating the LWFA stage as purely an accelerating structure and not as a source. Motivated by the pursuit of compactness, external injection of moderate-energy (< 60 MeV) electron beams into plasma will be explored using the Fourier-Bessel Particle-In-Cell (FBPIC) code. The sensitivity of the final beam quality to sub-optimal injection parameters will be explored. Bayesian optimisation is employed to assess whether sub-optimal injection parameters can be compensated for with laser and plasma parameters. This investigation presents working points from which future compact external injection designs can be optimised.

Speaker: Mr Jordan Byrne (University of Manchester, Cockcroft Institute)

14:00 Characterisation of linear and non-linear optics of the SOLARIS Storage Ring

This work presents a comprehensive characterization of the linear and non-linear optics of the SOLARIS storage ring under various operational conditions, including post-shutdown recovery and routine operation. Long-term studies were conducted using key diagnostic systems: the Bunch-by-Bunch Feedback (BBBF) system, LUMOS visible-light diagnostics, the PINHOLE X-ray beamline, and Turn-by-Turn (TBT) data from Libera Brilliance+. Measurements focused on fundamental machine parameters such as dispersion, beta functions, working point, chromaticity, synchrotron tune, and emittance, as well as the influence of insertion devices. Additionally, the impact of harmonic cavity settings, filling patterns, and chromaticity adjustments on emittance, bunch length, and beam lifetime was investigated. These results provide essential insights for optimizing beam quality, stability, and operational efficiency to enhance user performance at SOLARIS.

Speaker: Wiktoria Wiatrowska (SOLARIS National Synchrotron Radiation Centre)

14:00 Characterization of a Radially Polarized Terahertz Pulse for Dielectric Acceleration

In the last few decades, there has been an increased interest towards scaling down linear accelerators. The Terahertz (THz) Dielectric Accelerator developed, within the scope of the TWAC European project, is a technology that will tend toward that goal. The driving peak field for electron acceleration in the dielectric accelerator is directly related to the peak electric field and polarization of the THz source. On TWAC, we expect to obtain a high accelerating field in the dielectric through a multicycle THz pulse, and a cylindrically symmetric coupler which requires radial polarization. Here, we report on the experimental polarization characterization of the THz source. Firstly, we show the THz transverse profile. Then we mapped in 2D, through rasterization, the p- and s-polarization components of the THz pulse to discriminate the radial polarization. To end we show the preliminary measured coupling efficiency.

14:00 Characterization of longitudinal electron beam quality at the soft X-ray beamline of SwissFEL

Longitudinal electron beam quality is key at X-ray free-electron lasers (FELs), where electron beams with small slice energy spread and a well-preserved current profile are required to ensure optimal, stable performance. Collective effects such as microbunching instability (MBI) and intrabeam scattering (IBS) can significantly degrade the longitudinal phase-space of the electron beam during multi-stage compression and are therefore a concern across FEL facilities. In this contribution, we will present systematic characterization studies of these mechanisms at the SwissFEL soft X-ray beamline Athos. We will show longitudinal phase-space measurements using radiofrequency transverse-deflecting structures for different accelerator and compression conditions. These characterization studies represent a first step towards the optimization of multi-stage compression schemes aimed at mitigating MBI and IBS effects.

Speaker: Roberta Provvedi (Paul Scherrer Institute)

14:00 Characterization of Self-Modulation in a Plasma Wakefield Accelerator

AWAKE uses a long relativistic proton bunch (400 GeV, 48 nC) to drive wakefields in plasma. The amplitude of the wakefields increases along the plasma as the bunch undergoes self-modulation (SM). Wakefields are energy deposited in the plasma that must dissipate, a fraction of which is emitted as light. We measure the amount of light emitted to study the development of the wakefield amplitude along the plasma. We present experimental results that show: growth and saturation of SM along the plasma; differences in development of SM depending on the charge of the drive bunch and the plasma density; differences when SM is seeded (SSM) or developing as an instability (SMI). These observations are also confirmed by other diagnostics. However, this is the only diagnostic with multiple measurement points along the plasma, enabling observation of the SM process as it develops.

Speakers: Jan Mezger (Max Planck Institute for Physics), Jan Mezger (Max Planck Institute for Physics)

14:00 CMOS camera-based observation and characterization of multipacting during Cavity Conditioning

Raspberry Pi cameras (single board CMOS cameras) have already been successfully implemented for ion beam characterization at IAP Frankfurt and are now also being used to investigate multipacting during cavity conditioning. Multipacting appears caused by resonant secondary electron emission.
For the standalone rf conditioning of the FRANZ (Frankfurt Neutron Source) RFQ (Radio-Frequency Quadrupole) and the IH-DTL (Interdigital H-mode Drift-Tube-Linac), these cameras were installed both inside and outside the vacuum to detect multipacting and other cavity glowing effects. The occurrence of multipacting at specific power levels within the cavities can be confirmed by simulations.
In addition, the observed multipacting is characterized through spectrometer measurements.

Speaker: Leonie Bauer (Goethe University Frankfurt)

14:00 Commissioning of the Injector System for the X-Band Electron Linear Accelerator in Melbourne

The University of Melbourne’s X-band Laboratory for Accelerators and Beams (X-LAB) is developing a compact electron linear accelerator. The injector system will consist of a 100 keV DC photogun, a pulsed UV laser, an S-band (2.9985 GHz) RF buncher, and magnetic elements for beam transport. This paper reports on the commissioning of the injector system. We present the characterisation of the test laser and buncher, as well as initial electron beam measurements with Faraday cup. Particle tracking simulations using General Particle Tracer (GPT) code were used to obtain approximate optimal solenoid currents. We also report on the conditioning of the photogun, including photocathode inspection, vacuum performance, dark current, and stray radiation.

Speaker: Joel Valerian (The University of Melbourne)

14:00 Confinement of Electron Clouds in a Bending Magnet

Dipole-magnets in linear accelerators or synchrotrons are used to bend ion beams. In case of
intense ion beams, space charge compensation is a strategy to overcome intensity limits. So far
the reduction of the beams space charge is not investigated in bending magnets by experiments.
Therefore, a Gabor-lens was constructed and immersed in a H-type bending magnet to provide
a pure electron plasma. Usually, Gabor-lenses are ion optical devices used for focusing and
deflecting ion beams. With the setup presented in this paper it will be possible to compare the
bending of intense ion beams with and without space charge compensation. Furthermore, the
impact of spontaneous built-up of electron clouds observed in synchrotrons can be studied.
First experimental results compared with numerical simulations regarding the confinement of
electron plasmas within the dipole-Gabor-lens system will be presented. First beam dynamic
simulations will show the impact of space charge compensation within bending magnets.

Speaker: Fatima Jafari (Goethe University Frankfurt)

14:00 Coupled-bunch instabilities with a defocusing higher-harmonic RF system

Coupled-bunch instabilities restrict the beam intensity in many synchrotrons. These limitations can be mitigated by adding a higher-harmonic radiofrequency (RF) system, which modifies the potential well. Of particular interest is the bunch lengthening mode (BLM), in which the higher-harmonic voltage produces a defocusing effect at the bunch centre. By decreasing the peak line density, space-charge effects are reduced in hadron synchrotrons, while Touschek scattering is mitigated in synchrotron light sources. This contribution investigates the impact of a higher-harmonic RF system in BLM on the intensity threshold, growth rate, and mode behaviour of coupled-bunch instabilities. The influence of beam parameters such as the bucket filling factor, narrowband impedance properties, and RF system configuration is highlighted. Regimes in which BLM is advantageous or disadvantageous are compared to the ones for a single-harmonic RF system. The comparisons are based on semi-analytical solutions of the Vlasov equation as well as macro-particle simulations using the BLonD code.

Speaker: Ruben Heine (Technische Universität Berlin)

14:00 Crystal Channelling Optimisation in the LHC Using Reinforcement Learning

The Large Hadron Collider (LHC) requires a collimation system to ensure safe operation with both proton and heavy-ion beams. As of 2023, a crystal collimation scheme using bent silicon crystals was introduced to improve the collimation efficiency for heavy-ion beams. However, drifts in the crystal angular position led to the loss of cleaning performance during physics fills. These drifts are thought to derive from mechanical deformation of the goniometer due to heating caused by beam impedance effects. A quadratic-fit based optimiser was deployed to compensate for such drifts using feedback from beam loss monitors. This paper details the simulation environment to train reinforcement learning agents to maintain the optimal channelling position with increased reliability and reduced convergence time, and presents the latest results obtained with lead ion beams.

Speaker: Andrea Vella (University of Malta)

14:00 Crystal Radiators for Accelerators

Radiation emitted by charged particles in ordered crystalline structures can, through channeling radiation and coherent bremsstrahlung, yield enhanced, quasi-monochromatic photon peaks compared with the broad spectra from amorphous bremsstrahlung targets.
For electron beams from 50 MeV to several GeV, the photon yield can increase and the spectrum can be tuned by varying beam and crystal parameters[1].
These properties make oriented crystal radiators attractive for accelerator-based applications requiring high spectral brilliance, tunability, small angular divergence, such as polarized photon beams, positron production and X-ray generation, with implications for medical uses and detector calibration[2]. Within the INFN CORAL (Crystal radiatORs for AcceLerators) project, we use Geant4 simulations to model coherent processes and guide target optimization, including thermo-mechanical stress under heating and irradiation[3]. Forthcoming experiments will measure photon yield, spectral characteristics and emission stability over a wide energy range, including studies of the impact of heating and irradiation on intensity and degree of monochromaticity, in response to growing interest in replacing conventional bremsstrahlung targets for applications from nuclear fission and transmutation to high-intensity γ-ray beams for fundamental physics.
[1]V.Baier,V.Katkov,V.Strakhovenko,Singapore,1998
[2]G.Sushko, A.Korol,A.Solov’yov,PRAB,27(2024)100703
[3]A.Sytov et al., JKPS 83,132–139(2023)

Speaker: Pierluigi Fedeli (University of Ferrara)

14:00 Current Status of the High-Repetition-Rate Electron Driven Pulsed Muon Source at the SHINE Facility

Shanghai High-repetition-rate XFEL and Extreme Light (SHINE) Facility provides an 8 GeV, 1 MHz, 100 pC electron beam, offering a unique high-duty-cycle driver for generating muons—ideal for certain types of muon experiments, such as muon spin rotation techniques and muon lifetime measurements. We proposed an alternative approach to muon production using high-repetition-rate (kHz-MHz) electron beams generated by superconducting linacs at the SHINE facility. Our simulations for the target optimization and design of a surface muon beamline demonstrated the potential of electron-driven muon sources to complement muon-based fundamental and applied physics research while extending the capabilities of current and future XFEL facilities. However, transitioning to experiment presents challenges, including low per-bunch yield, high background, and the need for new measurement methods. Our 2026 beam test strategy uses a compact vacuum chamber to produce and implant muons into a stopping target. Positrons from muon decay will be detected via scintillator detectors, with decay time spectra used to extract yield and lifetime; a Helmholtz coil enables future spin studies. Progress includes finalizing the chamber and coil mechanical designs, validating the DAQ via cosmic muon lifetime measurements, and developing an end-to-end simulation framework with background characterisation studies that validate the measurement strategy.

Speaker: Jun Kai NG (Shanghai Jiao Tong University)

14:00 Damping Higher Order Modes for the Cool Copper Collider

For next generation particle collider designs, such as the Cool Copper Collider, small beam sizes, short bunch spacing, and beam stability are required to reach the luminosities desired to search for new physics. One challenge to overcome is damping the excitation of higher order modes in accelerating cavities. These modes are excited by wakefields induced by the beam, and must be removed before they are seen by the following bunch to prevent deflecting kicks that will spoil beam stability. The solution is the addition of damping slots on the accelerator cavities that can couple to these higher order modes and remove them from the central part of the cavity that the beam passes through, to reduce the kick factor of the mode. Additionally, these damping slots can lower the Q value for these modes, causing the excitation to die out between bunches because the mode cannot resonate in the cavity for as long. In this study, we optimize the damping slot geometry to remove higher order modes from the accelerating cavity while preserving the fundamental accelerating mode.

Speaker: Sophia Morton (SLAC National Accelerator Laboratory)

14:00 Defect Engineering of Transition Metal Oxide Films Employing Low Energy Ion Accelerator for Emerging Non-Volatile Memory Application

Accelerator-enabled ion irradiation is a versatile technique for tailoring the structural and electrical properties of materials. By enabling precise defect creation over targeted regions, ion beams provide an effective way for advancing oxide-based electronic devices. This capability is crucial for emerging memory technologies like Resistive Random Access Memory (RRAM), where defect configuration critically governs resistive switching behavior in metal/insulator/metal structures.
In this work, we investigate the impact of low-energy Ag and Kr ion irradiation on titanium oxide (TiOx) and tantalum oxide (TaOx) thin films used in RRAM devices. The oxide films are fabricated at room temperature employing RF magneton sputtering technique. The 50 keV Ag ion irradiation (fluences: 1×10¹⁵, 3×10¹⁵, 1×10¹⁶ ions/cm²) was performed at HZDR, Dresden, Germany, while the 100 keV Kr ion irradiation (fluences: 3×10¹⁵, 1×10¹⁶, 3×10¹⁶ ions/cm²) was carried out using an ECR-based low-energy particle accelerator at IUAC, New Delhi. The result shows that pristine TiOx devices, which initially exhibited no switching, demonstrated an enhancement in resistance ratio >100 after irradiation with both Ag and Kr ions. In contrast, the TaOx-based devices undergo excessive defect accumulation. Additionally, accelerator-driven techniques, RBS and resonant RBS, together with synchrotron-based XPS, were utilized to enable comprehensive elemental and chemical analysis.

Speaker: Disha Yadav (University of Petroleum and Energy Studies)

14:00 Demonstration of mode-locked frequency comb for an x-ray free-electron laser

X-ray free-electron lasers (FELs) are powerful photon sources offering a wide wavelength range, subfemtosecond pulse duration, and high brightness. Most X-ray FELs are based on self-amplified spontaneous emission (SASE). SASE-FEL radiation has excellent transverse but only limited longitudinal or temporal coherence, with power and spectral profiles consisting of multiple randomly distributed spikes. In this contribution, we present the first experimental demonstration of mode-locked SASE, which generates periodic trains of phase-locked subfemtosecond pulses, thus providing an X-ray analog of the optical frequency comb. Our approach combines the mode-coupled SASE scheme, where magnetic chicanes between the undulator modules of the FEL increase the coherence of the output radiation, and an external optical laser that restricts the FEL amplification to periodic and short regions of the electron bunch. The work relies on evidence in the frequency and time domains for photons and electrons, respectively, and will benefit investigations of ultrafast dynamics as well as coherent spectroscopy, and enable new types of experiments requiring phase-correlated X-ray pulses.

Speaker: Wenxiang Hu (Paul Scherrer Institute, ETH Zurich)

14:00 Design and Experiment of Energy Feedback Unit for 15 kV/15 kA AMD Excitation Pulse Source

Abstract:
The Super Taume-Charm Facility (STCF), a new generation of electron-positron collider led by the University of Science and Technology of China, requires a high-quality positron source to sustain high-luminosity continuous operation. The Adiabatic Matching Device (AMD) is a critical component for positron focusing, its excitation pulse source requires a peak current ≥15 kA and a pulse front edge ≤3.5 us. To reduce the significant power dissipation of pulse discharge system, an energy feedback circuit was designed. The optimized system achieved a dramatic reduction in losses, decreasing input power by 73.96% and enhancing long-term operational stability. This article provides a detailed account of the simulation of power loss in AMD excitation pulse sources, as well as the design, simulation, and offline debugging of energy feedback circuits.

Key words: excitation pulse power for AMD; power loss; energy feedback; photoconductive semiconductor switch

Speaker: Zichen Zhong (University of Science and Technology of China)

14:00 Design and Implementation of a Cavity Voltage Feedback Tracking Algorithm for Double RF Systems

In next generation light sources, double RF systems are widely employed to lengthen bunches, thereby enhancing the Touschek lifetime and suppressing IBS effects. However, the harmonic cavity (HC) in such systems can drive various types of longitudinal instabilities, which severely impede effective bunch lengthening. In theory, a low-level feedback (LLRF) system can be used to selectively modify the cavity impedance to suppress these longitudinal instabilities. In this paper, we design a physical model for such a LLRF feedback system and implement its functionality in code. This implementation is subsequently integrated as a module into an existing longitudinal tracking simulation program. Simulation results from the new code show excellent agreement with theoretical impedance analysis, providing strong support for the design of feedback parameters.

Speaker: Jincheng Xiao (University of Science and Technology of China)

14:00 Design and low-power measurements of an X-band parallel-coupled accelerating structure

To meet the requirement for high-gradient accelerating structures in future compact accelerator systems, this work presents the design, fabrication, and preliminary testing of an X-band 11.424 GHz parallel-coupled accelerating structure. The structure consists of 16 cells and operates in the π mode, with an optimal filling time of approximately 50 ns under over-coupling conditions. The prototype has been successfully fabricated, followed by low-power measurements and bead-pull field distribution. The results show that machining errors are within 5 µm, satisfying the tolerance requirements. These results provide a solid foundation for the subsequent high-power tests.

Speaker: Zhicheng Huang (University of Science and Technology of China)

14:00 Design and Optimization of a Fast Electrostatic Chopper for FLASH Proton Therapy Radiobiology Experiments.

FLASH proton therapy has shown the potential to reduce normal-tissue toxicity while maintaining tumor control by delivering radiation in ultra-high dose-rate pulses (>40 Gy/s). However, more radiobiology experiments are needed to better understand the subjacent mechanism and optimize its application beam parameters. To explore this regime using the Cyclotron at Centro Nacionalicémoste de Aceleradores in Seville, we
have developed a fast electrostatic chopper for length beam structure manipulation in order to be able to produce short (~1 um) and high intensity pulsed beams. In this paper, we present the design and optimization of this device, intended to generate well- defined beam pulses for radiobiology experiments in the FLASH regime. Electromagnetic
simulations were performed with CST Particle Studio to define the electrode geometry, determine the required operating voltage, and carry out tolerance studies for the mechanical design. The designed chopper was integrated into a full TOPAS model of the external cyclotron beamline to evaluate the need of additional subsystems such as a
collimator and to optimize the operational parameters. First studies carried out with this model are also presented.

Speaker: Demetrio Hermenegildo Saucedo Cuberes (Universidad de Sevilla)

14:00 Design and optimization of a horn focusing system for efficient pion capture in a Muon Collider Demonstrator

This study investigates magnetic horn focusing as an alternative to superconducting solenoids for the Muon Collider Demonstrator. We explored a double horn structure as an R&D exercise for a possible muon-collider frontend, tailored to capture pions in the 100-400 MeV/c momentum range. An XGBoost-based optimization pipeline was applied to refine geometric and current parameters to maximize pion yield while maintaining acceptable emittance. To validate performance, we benchmarked the single horn structure against IMCC design baselines and compared the optimized double horn structure with the solenoid channel, using Geant4 and FLUKA simulations. The results provide a critical assessment of the trade-offs between the lower-cost magnetic horn approach and superconducting solenoids, offering a potential pathway for a more economically viable Muon Collider Demonstrator.

Speaker: Prateek Rao (University of Wisconsin–Madison)

14:00 Design and Theoretical Analysis of a Highly Compact Triple-folded 20 MHz Quarter-Wave Cavity for SSMB

To meet the energy compensation requirements of Steady-State Micro-Bunching (SSMB), a 20 MHz RF cavity with extreme axial compactness is essential. This paper presents an innovative triple-folded quarter-wave cavity design that overcomes the size limitations of conventional structures. Based on cascaded transmission line theory, we established an analytical model to optimize the cavity’s shunt impedance and tuning range. A triple-folded 20 MHz prototype was designed and validated via CST simulations, showing that the axial length is compressed to 1.25 m (approximately 1/3 the length of a standard QWC) while achieving a high shunt impedance of 558 kΩ with excellent thermal stability. This compact design offers a high-efficiency solution for low-frequency RF systems.

Speaker: Peizhi Fang (Tsinghua University)

14:00 Design of 166 MHz and 500 MHz Bimodal RF Cavities Based on Coaxial Coupling

Ultra-low emittance is one of the primary directions for the development of synchrotron radiation facilities. To manage coupled-bunch instabilities and achieve beam lifetime expectations, higher-harmonic cavities have become a common requirement for diffraction-limited storage rings. bimodal cavities are considered a multifunctional and compact accelerating structure capable of integrating the functions of a fundamental RF cavity and a higher-harmonic cavity. To meet the demands of low-energy storage ring light sources development, we propose an active bimodal RF cavity operating at low frequencies of 166 MHz and 498 MHz, and coaxial couplers is designed.

Speaker: Dinghui Su (Shanghai Institute of Applied Physics)

14:00 Design of a 10-MHz High-Energy-Resolution Light Source

High energy resolution is essential for advanced spectroscopic studies of quantum materials, especially for resolving low-energy electronic features in angle-resolved photoemission spectroscopy (ARPES). However, existing light sources for ARPES still face difficulties in simultaneously providing narrow bandwidth and high photon flux. We are developing a 10-MHz coherent light source based on angular-dispersion-induced microbunching (ADM), aiming to generate narrow-band radiation with sub-meV-level energy resolution. Start-to-end simulations from the injector to the radiator have been performed to evaluate the beam dynamics and radiation performance. The simulation results show that the proposed source can provide sub-meV-level energy resolution and a photon flux above $10^{12}$ photons/s over a broad photon-energy range.

Speaker: JunHao Liu (Shanghai Advanced Research Institute)

14:00 Design of a S band RF gun with heavy beam-loading for the injector of SSMB light source

Steady-State Microbunching(SSMB) light source is a highly potential new type of light source, which combines the advantages of synchrotron radiation and FEL. It possesses the characteristic of both high repeat frequency and high peak power. In order to build such a light source, we are trying to design a 20ns, 0.7A burst mode injector to produce high brightness electron beam, and we have already designed a S band RF gun for this injector.

Speakers: Lianmin Zheng (Tsinghua University), Yingchao Du (Tsinghua University), Zhengkai Wang (Tsinghua University)

14:00 Design of a Short-Pulse Septum Power Splitter for Distributed X-band High-Gradient Acceleration

Using short radiofrequency (RF) pulses is a promising
method for increasing achievable accelerating gradients
while significantly suppressing RF breakdown probability.
However, short-pulse operation requires a structure with a
commensurately low filling time to ensure efficient gradient buildup. To achieve this, we utilize a distributed power
coupling scheme that delivers RF power to each cavity simultaneously through a waveguide array. This parallel feeding mechanism drastically reduces the filling time of the
entire accelerating structure compared to traditional series-fed designs. Furthermore, this topology allows for greater
flexibility in cavity optimization and yields higher shunt
impedance.This work presents the design and simulation
of a novel septum power splitter specifically engineered to
drive an accelerating structure in this short-pulse regime.
The splitter is integrated with a four-cell prototype, enabling
each cavity to be powered individually and concurrently. The
system is designed for short 𝑋-band RF pulses with peak
powers up to 400 MW at 11.7 GHz. The four-cell structure
is over-coupled and maintains a (2/3)𝜋 phase advance between adjacent cells. CST simulation results confirm the
performance of this design in achieving high accelerating
gradients. Finally, we outline the experimental plan for the
prototype demonstration at the Argonne Wakefield Accelerator.

Speaker: Salih Colmekci (Northern Illinois University)

14:00 Design of an Alpha-magnet-based High-repetition-rate Megaelectronvolt Ultrafast Electron Diffraction Beamline

We propose a novel MeV UED beamline design based on a normal-conducting very-high-frequency (VHF) electron gun that generates a high-quality electron beam at a megahertz (MHz) repetition rate. Beam compression and time-of-flight (TOF) control are achieved using an alpha-magnet. Simulations show compression of the 4.1 fC electron beam to a duration of 4.7 fs RMS, with a TOF jitter of 1.9 fs RMS, alongside normalized transverse emittances of 5.6 nm·rad in the x-direction and 5.2 nm·rad in the y-direction. This design substantially enhances both the signal-to-noise ratio and temporal resolution of the UED beamline, establishing a robust foundation for the future development of UED facilities.

Speaker: Baiting Song (Tsinghua University)

14:00 Design of an Improved S-Band SLED Pulse Compressor

This paper presents the design of an improved SLED pulse compressor for our beam test platform at National Synchrotron Radiation Laboratory (NSRL). It consists of a 3 dB hybrid, a TE10-TE01 mode converter, and a resonator storage cavity. Through geometrical optimizations, the resonator is designed to operate in the TE0,1,10 mode, which offers a high intrinsic quality factor while maintaining cost-effectiveness. Additionally, the conventional cylindrical configuration has been modified to a double-ended conical structure, which facilitates better mode isolation.

Speaker: Yelong Wei (University of Science and Technology of China)

14:00 Design of an X-band compact mode converter for converting TE10 mode to TE01 mode

This paper presents the design of a compact and efficient rectangular waveguide TE10 to circular waveguide TE01 mode converter operating in the X-band. By incorporating two choke slots, the design achieves a high-purity circular waveguide TE01 mode. The optimized results show that at the operating frequency of 11.424 GHz, the conversion efficiency for the circular waveguide TE01 mode is calculated to be approximately 100%, while the reflection coefficient is better than -50 dB. The bandwidth reaches more than 260 MHz for the transmission coefficient while the bandwidth is approximately 210 MHz for the reflection coefficient better than -20 dB.

Speaker: Chengzhe Wang (University of Science and Technology of China)

14:00 Design of compact large momentum acceptance separate function magnet beamlines for particle therapy

The University of Melbourne’s TURBO (Technology for Ultra Rapid Beam Operation) project aims to improve charged particle therapy by developing large momentum acceptance beamlines to reduce the energy layer switching time, increasing the efficiency of delivery systems for cancer treatment. Previously, a closed-dispersion arc has been designed utilizing non-linear magnets built as Halbach arrays, which achieves up to ±42% rigidity acceptance in a beamline with an overall bend of 30°. Here – considering the technological complexity of these non-linear magnet arrays – we present a design methodology for compact large momentum acceptance beamlines based on separate-function magnets. We find parameters representing clinical beam quality requirements and perform a multi-objective optimization to investigate trade-offs between them. The separate-function approach provides an alternative for a full-scale beamline that relies on simpler, commercially available technology.

Speaker: Simon Barg (The University of Melbourne)

14:00 Design of Ionization Profile Monitors at the Integrable Optics Test Accelerator (IOTA) Facility at Fermilab

The Integrable Optics Test Accelerator (IOTA) at Fermilab is transitioning from an electron beam facility to a proton beam facility for studies in nonlinear accelerator optics and space-charge dominated proton beams. This project involves the commissioning and fabrication of Ionization Profile Monitors (IPMs) to enable beam profile measurements at IOTA. In general, IPMs work on principle of residual gas ionization by the beam to generate beam profile. This work focuses on a mechanical design that leverages a controlled injection of noble gases, primarily Argon, as the ultra-high vacuum of the IOTA ring provides insufficient residual gas for ionization. Efforts to understand vacuum integration to ensure compatibility with the storage ring environment, the integration of real-time data acquisition systems and the commissioning of the IPMs will be discussed. This project provides a versatile diagnostic tool, supporting IOTA’s role as a testbed for larger-scale accelerator facilities and contributing to the broader understanding of beam physics in high-intensity, high-space-charge regimes.

Speaker: Matilda Mwaniki (Illinois Institute of Technology)

14:00 Developing a Physics-Informed Gaussian Process Model to Construct an Uncertainty-Quantified Machine Model Using Bayesian Optimization

For maintaining the designed optical performance of machines like the GSI heavy-ion synchrotron SIS18 or the FAIR fragment separator SFRS, accurate knowledge of magnetic field and element alignment is crucial. A Gaussian Process model with a physics-informed kernel based on a stochastic ensemble of lattices is proposed.
Key advantages compared to LOCO (Linear Optics from Closed Orbits) include (1.) fitting of Gaussian probability distributions for parameters, which inherently model uncertainty, (2.) incorporation of measurement uncertainty from BPM noise, (3.) uncertainty-enabled orbit prediction between BPMs, and (4.) an active-learning strategy for greater sample efficiency than measuring an orbit response matrix. Applied in a simulation of SIS18, the method constructs an effective machine model with minimal orbit uncertainty around the ring, enabling orbit correction with uncertainty-quantified minimal deviation at any location. The SFRS is identified as a compelling target for future application, where sparse instrumentation and complex optics make uncertainty-aware modeling particularly valuable.
This physics-informed GP framework provides uncertainty-enabled modeling for rings and beamlines, with potential applications extending to broader optics-correction and beam-tuning tasks.

Speaker: Victoria Isensee (Technical University of Darmstadt)

14:00 Development and Characterization of a FEBIAD Ion Source for RI Beam Production at the RAON ISOL System

RAON is a heavy-ion accelerator facility in Korea that uniquely combines ISOL (Isotope Separation On-Line) and In-Flight (IF) techniques to produce a wide range of Rare Isotope (RI) beams. In the ISOL system, ion sources are continuously being developed to expand RI beam production capabilities. Among them, the Forced Electron Beam Induced Arc Discharge (FEBIAD) ion source is a promising candidate for efficient RI beam generation.
A prototype FEBIAD ion source was evaluated at the offline facility, where successful Ar, Kr, and Xe isotope beam extraction demonstrated its operational feasibility. Since the FEBIAD ion source operates at elevated temperatures, structural deformation due to thermal expansion can occur. In particular, bending and variations in the gap between the anode grid and cathode have been identified as critical issues.
To mitigate these effects, a new FEBIAD ion source design was developed and fabricated to ensure structural stability under high-temperature conditions by adding a heating strip and allowing the body to slide. The fabricated ion source successfully achieved Kr isotope beam separation in offline tests, and subsequent online experiments confirmed stable operation of the source under ISOL conditions, demonstrating its suitability for reliable RI beam production. Future work will involve RI beam extraction experiments using various targets within the RAON ISOL system.

Speaker: Je Hwan Han (Institute for Rare Isotope Science)

14:00 Development and First Beam Observations of an Ultra-Fast Bunch-by-Bunch X-ray Beam Size Monitor at SuperKEKB

SuperKEKB is an electron–positron collider that aims to exceed its own world-record instantaneous luminosity by an order of magnitude. During high-current collision operation, various beam instabilities—such as sudden beam loss, electron-cloud effects, and fast-ion instability—can limit beam performance and stable machine operation. To better understand these phenomena, fast diagnostic systems capable of resolving the behavior of individual bunches within a bunch train are essential. To address this need, we have developed a new bunch-by-bunch X-ray beam size monitor. Synchrotron radiation emitted from a bending magnet is passed through a coded-aperture optical element and imaged onto a silicon strip detector. High-speed sampling of the detector signals enables vertical beam size measurements for every bunch in the SuperKEKB main ring with a temporal spacing of approximately 4 ns. This presentation reports an overview of the monitor development, results from initial performance testing and commissioning, and the first beam observations obtained using this diagnostic system.

Speaker: Riku Nomaru (The University of Tokyo)

14:00 Development and preliminary testing of a digital feedback system

This paper introduces the development and preliminary testing of a digital bunch-by-bunch feedback system designed to suppress beam oscillations. Coupled-bunch instabilities, which arise under high-current and multi-bunch operation modes, can induce beam oscillations that significantly degrade collision luminosity and reduce beam lifetime. These instabilities necessitate active feedback suppression. Based on a field-programmable gate array (FPGA) as the core processor, this work independently designed a finite impulse response (FIR) digital filter suitable for transverse feedback and developed the corresponding signal processing electronics. Each functional module of the electronics was tested, with results aligning with design expectations. Furthermore, a comparative analysis was conducted between two filter design methods—the time-domain least squares method and the selective filter method—to determine the optimal algorithm and parameters.

Speaker: liang xu (Institute of High Energy Physics, Chinese Academy of Sciences)

14:00 Development of a Bunch-by-Bunch BPM Measurement System at SSRF Based on Machine Learning

Real-time bunch-by-bunch monitoring of transverse position and longitudinal phase has become increasingly important for the stable operation of storage ring light sources and for accelerator physics studies. This paper presents a real-time three-dimensional bunch-by-bunch position measurement system based on machine learning. The system eliminates the need for sampling delay adjustment and avoids complex front-end circuitry by directly digitizing BPM electrode signals with high-speed ADCs at a sampling rate of five times the storage ring RF frequency. By deploying neural network models within the FPGA, the system simultaneously achieves real-time measurement of the transverse position and longitudinal phase with low latency. Beam experiments were conducted at Shanghai Synchrotron Radiation Facility (SSRF) to validate the system’s phase measurement capability. The results demonstrate a bunch-by-bunch phase resolution of 0.4ps while maintaining a measurement latency within 1µs.

Speaker: Jialan Pan (Shanghai Institute of Applied Physics)

14:00 Development of a Gas-Target Laser Ion Source Test System for the LaPRIS Concept

In order to achieve high energy resolution in nuclear physics experiments, it is important to maintain the beam quality during beam transport from the injector to the accelerator and to the experimental instruments. At the Research Center for Nuclear Physics (RCNP), the University of Osaka, high-resolution beams are currently obtained by injecting beams from an ECR ion source into the accelerator and collimating them with slits throughout the acceleration. However, this method leads to increase losses of beam intensity and a beam halo, so it is desired to generate high-quality beams directly at the ion source without collimations.
As a solution to the issues, we are developing the LaPRIS (Laser Plasma RF Ion Source) method. LaPRIS is a pulsed ion source that generates and extracts slow ions by combining a gas jet, an RF field and ultra short pulse laser. In this method, the ions are extracted from plasma generated at the laser focal spot by RF field. They form a short-pulsed bunch with a small spatial and time profile.
In this paper, we will discuss preliminary results obtained by generating laser-induced plasma through focused laser in a jet of thin gas and measuring the generated ions.

Speaker: Shotaro Matsui (The University of Osaka)

14:00 Development of a High-Temperature Electron Beam Test Stand for Thermal Studies of the TATTOOS target at PSI

The Targeted Alpha Tumor Therapy and Other Oncological Solutions (TATTOOS) facility at the Paul Scherrer Institute (PSI) will address the growing demand for medically relevant radionuclides using proton-induced spallation at the PSI High Intensity Proton Accelerator (HIPA). The target is designed to operate with a 100 microA - 590 MeV proton beam at up to 2400 °C for 2–5 weeks. To study thermal mechanisms critical to target performance, a high-temperature test stand was developed based on PSI’s 60 keV, 100 mA electron beam welding machine. This setup allows heating tantalum foils in vacuum to melting temperatures while investigating thermal shock response, emissivity enhancement techniques, and temperature distributions using a Gaussian beam profile with wobbling frequency up to 1000 Hz.
We will present here the static and wobbled beam profiles measurement using a 50 μm tungsten wire scanner moving up to 60 mm/s, with thermionic emission suppressed via voltage biasing. Then, FLUKA and CASINO simulations will show the penetration and scattering differences between the 590 MeV proton and 60 keV electron beams. Finally, temperature measurement for various rotation radii will be presented. Despite differing heating mechanisms, the resulting thermal behavior is directly comparable, supporting target design under realistic operating conditions.

Speaker: Rémi Martinie (Paul Scherrer Institute)

14:00 Development of a new ultraslow muon beam diagnostic system for the J-PARC muon g-2/EDM experiment

The E34 experiment at J-PARC MLF aims to precisely measure the positive muon's anomalous magnetic moment and electric dipole moment.

Two technical challenges are critical. First, the ultraslow muon source (from muon cooling) must achieve its target intensity ($10^6 \mu^+/\text{sec}$) and low-emittance ($\epsilon_{x, \text{rms,normalized}}: \sim 0.3 \pi [\text{mm}\cdot\text{mrad}], \epsilon_{y, \text{rms,normalized}}: \sim 0.1 \pi [\text{mm}\cdot\text{mrad}]$). Second, the low-energy (5.7 keV) beam is highly sensitive to ambient magnetic fields and must be matched to the accelerator's acceptance with <10% accuracy, requiring active trajectory correction while preventing emittance growth.

To verify these conditions—muon source property and beam matching—we developed a new ultraslow muon beam diagnostic system.
In this system, the control section uses electrode pairs to actively correct the beam trajectory, which is sensitive to ambient fields. The transport section removes background particles (using an electrostatic mirror and bending magnet) and focuses the beam (using electrostatic quadrupoles). The measurement section uses the Q-scan method to measure the beam property.

Simulations were used to optimize the system for 100% transport efficiency and <10% emittance measurement accuracy. Subsequent commissioning confirmed the system is ready for the quality evaluation of the beam in the new experimental area.
This poster will discuss the simulation and commissioning results.

Speaker: Mayu Wada (The University of Tokyo)

14:00 Development of STCF S-Band High-Gradient Traveling Wave Accelerating Structures

The Super Tau-Charm Facility (STCF) is a next-generation electron--positron collider project proposed in China, designed to explore frontier physics in the tau-charm energy region. The facility's accelerator is required to provide electron and positron beams with tunable energies ranging from 1.0 to 3.5 GeV. This study presents the design of a traveling-wave accelerating structure for the STCF. By optimizing the regular-cell configuration, a high shunt impedance is achieved. The peak electric field in accelerating structure is reduced by adjusting the accelerating gradient profile, and an under-coupled output coupler design is adopted to enhance the performance of the accelerating structure. The objective is to achieve an accelerating gradient of 22.5 MV/m with an input power of 45.3 MW, and to further increase the power in pursuit of high-gradient operation in the S-band.

Speaker: ShaoHang Ma (University of Science and Technology of China)

14:00 Development of the spin tune model for EDM investigations at storage rings

Electric Dipole Moments (EDMs) are sensitive probes of CP violation and could help address some open questions of the Standard Model. Recent advances in storage ring and polarimetry technologies enabled the development of a new experimental method for EDM investigations. One of the main parameters involved in the EDM studies via storage rings is the Spin Coherence Time (SCT), i.e., the time during which the spins of all particles in a stored beam precess coherently. A long SCT increases the experimental sensitivity and minimizes the statistical uncertainties. To identify the optimal working conditions, the single-particle spin tune, defined as the number of spin precessions around the vertical axis per revolution, must be tracked with extremely high precision. A lattice-independent model was developed to accurately track the spin tune of single charged particles in a variety of storage rings, both existing and proposed, and was directly applied to SCT optimization. In this contribution, the model was tested on the hybrid storage ring, a new generation device conceived for EDM investigations, which uses electrostatic deflectors for confinement and magnetic quadrupoles for focusing.

Speaker: Anna Piccoli (University of Ferrara, Istituto Nazionale di Fisica Nucleare, Sezione di Ferrara)

14:00 Dielectric Characterization of Beam Line Absorber Samples for Next-Generation High Intensity Electron Beam SRF Accelerators

PERLE, under construction at IJCLab, is a multi-turn Energy Recovery Linac designed for high intensity electron beams of 10 MW peak power (20 mA, 250 MeV). Simulations of its SRF cryomodule * predict more than 100 W of higher-order-mode (HOM) power per cavity induced by the short bunches, indicating that Beam Line Absorbers (BLAs) at 40 K may be required between cavities to dissipate the HOM power and protect the 2 K stage. However, the lack of complete properties of dielectric materials for candidate absorbers limits accurate BLA design. To address this, we are conducting dedicated studies of BLA materials at IJCLab. We measured the broadband dielectric properties of Kyocera SC1000 samples from BNL ** at room temperature using a setup at CLIC (CERN) and cross-validated the results with independent measurements from JLab***. In parallel, we designed and simulated two cryogenic coaxial test stands, one operating up to 18 GHz and another extending coverage to 40 GHz. These warm measurements provide baseline data for upcoming cryogenic studies and validated input for the design of BLAs in next-generation accelerators such as the EIC at BNL, FCC-ee at CERN, and in particular PERLE at IJCLab.

Speaker: Axel Perez Ruiz (Accelerators & Cryogenic Systems, Université Paris-Saclay, CNRS/IN2P3, IJCLab)

14:00 Differentiable Phase Space Map for the Beam-Beam Force

A model of the beam-beam force for strong-weak simulations has been implemented in the SciBmad library, including variations of the beam size and beam centroid across the interaction region. Similar to models in the Bmad ecosystem, the SciBmad implementation simulates the weak-strong interaction of 6D beam distributions, where only the weak beam becomes non-Gaussian due to single-particle dynamics. Accurate modeling is complicated when strong final focusing varies the strong-beam size along the interaction point, and when crab cavities introduce a sinusoidal centroid shift. To capture these effects, the strong beam is axially subdivided into N equal-charge slices, each treated as a Gaussian distribution. Each weak particle is drifted to the IP center and then sequentially drifted to and kicked by each slice, both transversely and longitudinally, before being drifted back to the IP. To enable high-order nonlinear analysis of the interaction, SciBmad uses the GTPSA.jl truncated power series algebra package. The resulting implementation produces a differentiable phase space map of the interaction that can be evaluated and differentiated to arbitrary order. This map-based formulation is well suited for lattice optimization, machine-learning surrogate modeling, and nonlinear studies including resonance driving term analysis. The nonlinear maps also allow for the analysis of symplecticity of complex beam-beam interactions, in addition to symplectification of beam-beam tracking.

Speaker: Evan Navar Root (Cornell University (CLASSE))

14:00 Dipole powering failure criticality and mitigation for FCC-ee

The electron-positron Future Circular Collider (FCC-ee) will initially operate at the Z-pole energy of 45.6 GeV with beams composed of 12\,000 bunches, storing a total energy of 17.5 MJ per beam. Combined with small emittances, this results in extremely high beam energy densities that pose a significant damage risk to accelerator components. A comprehensive
assessment of powering failure scenarios is therefore essential to ensure safe machine operation. This study evaluates the impact of a powering failure in one of the main dipole circuits using the Local Chromaticity Correction (LCC) lattice configuration. Multi-turn bunch tracking simulations are performed to determine the beam response and assess failure criticality. We interpret these novel results with respect to previously established results for the Global Hybrid Correction (GHC) lattice. Horizontal orbit excursions are found to develop over a significantly longer timescale than for the GHC lattice. The underlying physics of this behaviour is analysed in detail, with emphasis on the role of the modified sextupole configuration in the arcs. Based on these findings, the implications for machine protection system design, including interlocking requirements and detection strategies, are discussed and mitigation measures are proposed.

Speaker: Delphine Domange (European Organization for Nuclear Research)

14:00 Dispersion Suppression for Wedge-Based Final Cooling at a 10 TeV Muon Collider

Reaching $10^{34}$ $\rm{cm}^{-2}s^{-1}$ luminosity range in a $10$ TeV Muon Collider within the short lifetime of the muon requires the reduction of the 6D emittance of the muon beam in a process described as muon ionization cooling. In the final cooling stage, the transverse emittance must be reduced to $22 \mu$m, typically by allowing longitudinal emittance growth up to downstream acceptance limits. While the current International Muon Collider Collaboration designs additionally involve $40$ T solenoids to reach the transverse emittance target, such high-field solenoids come with a number of disadvantages, including mechanical stress management, quench protection, and potential limitations in relying on High Temperature Superconductor technology. Designed as an alternative to using such solenoids while simultaneously reaching target transverse emittance, the previously proposed wedge-based, reverse emittance-exchange cooling scheme requires excellent dispersion suppression. In this study, we design and simulate a dispersion suppressor channel for the wedge-based final cooling design that reduces dispersion in the target direction to a target value of $D_x = 0.0036$ m.

Speaker: Inci Karaaslan (University of Chicago)

14:00 Effect of the Laser Polarization on Electron Acceleration in Carbon Nanotube Targets

Structured carbon-nanotube targets can be used as a medium for accelerating self-injected electrons within a laser-driven wakefield bubble, analogous to blowout laser wakefield acceleration (LWFA) in gaseous plasmas. A previous numerical work demonstrated this behavior using a three-cycle, 800 nm, circularly polarized laser pulse with a peak power of 35.5 TW. In this study, we compare electron beam properties for linearly and circularly polarized pulses interacting with a same target. We find that, in both cases, the analyzed beam parameters exhibit similar values, with only small discrepancies during the acceleration process inside the target and remaining nearly identical after extraction. Total charge, median energy, emittance, and divergence remain comparable for both polarizations, with only the energy spread showing an appreciable difference of approximately 8%.

Speaker: Bruno Silveira Nunes (Instituto de Pesquisas Energéticas e Nucleares)

14:00 Efficient Design of an 8-Conductor Nonlinear Kicker for HALF Using a Python-Based Toolchain

The beam injection system of the Hefei Advanced Light Source (HALF) utilizes a nonlinear kicker (NLK) based on an 8-conductor geometry. Due to the presence of the internal vacuum chamber and the high sensitivity of the magnetic field distribution to the conductor positions, the design of an 8-conductor NLK demands extreme precision and poses significant technical challenges. To address these issues, an automated design toolchain integrating Opera-2D and Python was developed in this study. A Bayesian optimization algorithm, implemented via the Optuna library, was employed to search for optimal conductor configurations while satisfying stringent constraints on magnetic field quality and spatial positioning. The optimization framework successfully identified a set of feasible design parameters for the HALF NLK within only [40] iterations. Compared with manual iterative methods, this automated approach significantly improves R&D efficiency, providing a generalized tool for 8-conductor NLK design and offering an effective solution for complex optimization problems of non-linear magnets in synchrotron light sources.

Speaker: Weibo Hu (University of Science and Technology of China)

14:00 Efficient Slice Energy Spread Measurement Using Two Screens

The slice energy spread is a critical parameter in free-electron laser (FEL) facilities. A high-brightness injector is typically characterized by a low slice energy spread, which can induce micro-bunching instability and consequently degrade the FEL lasing process. Conventional mitigation involves controlling the slice energy spread using a laser heater, making its precise measurement essential.

Approaches has been proposed based on polynomial fitting after scanning the beam size at different energies or dispersions. However, these approaches are time consuming.

We have developed a simpler method for measuring slice energy spread by employing two screens in dispersion stage. With a proper set of parameters, we can locate the beam waist at the middle of two screens, and get the slice energy spread quickly. This method has been performed at SHINE injector. The measurement was completed in less than one hour, and the result turned out to be 2.3keV, which fits with the simulated value.

This method can greatly improve the efficiency of energy spread measurement, saving time and effort for beam diagnostics.

Speaker: ShengBin Ye (ShanghaiTech University)

14:00 Electron beam formation in a thermionic electron gun

This work presents the development of a collimated electron beam suitable for acceleration in dielectric laser accelerators (DLA). A thermionic electron gun was designed to produce a stable ~0.2 mm beam under high-vacuum conditions with electron energies of 10–47 keV. Beam emission and focusing parameters were optimized to enable reliable injection into compact accelerating structures. To ensure the required vacuum quality, a custom hydrogen-based leak detector was developed and successfully applied to identify and eliminate leakage in the beamline. Additionally, a beam deflection system and diagnostic tools for measuring beam current and electron yield were implemented and tested. The results confirm the feasibility of the proposed solutions and highlight the potential for further advancement of compact accelerator technology.
ACKNOWLEDGMENTS THE STUDY IS SUPPORTED BY THE NATIONAL RESEARCH FOUNDATION OF UKRAINE UNDER THE PROGRAM “EXCELLENT SCIENCE IN UKRAINE” (PROJECT # 2023.03/0182).

Speaker: Serhii Kovalov (National Science Center Kharkiv Institute of Physics and Technology)

14:00 Elliptical Beam Shaping in a Standard Bow-Tie Planar Four-Mirror Optical Enhancement Cavity Using a Cylindrical Lens

The standard bow-tie (SBT) planar four-mirror optical enhancement cavity can amplify laser power, circulate laser pulses, and adjust the laser beam waist. It is widely applied in fields such as steady-state micro-bunching light sources, inverse Compton scattering light sources and fusion energy. However, the different effective radii of curvature in the sagittal and tangential directions vary with the incidence angle, which in turn leads to an elliptical cavity mode. Conventional approaches suppress this effect by restricting the transverse dimensions of the cavity, but this sacrifices the transverse design freedom of the optical enhancement cavity.
This paper proposes an elliptical cavity mode correction method using a cylindrical lens, enabling the fundamental mode at the beam waist to recover a circular shape. The method utilizes a cylindrical lens to differentially compensate the wavefront curvatures in sagittal and tangential directions, eliminating elliptical spot distortion without compressing the transverse dimensions of the cavity. Consequently, it overcomes the design constraints on the transverse size of the optical enhancement cavity and provides a new approach for designing large-volume, high-power optical enhancement cavities.

Speaker: Mr Guojiang Zhang (Tsinghua University)

14:00 Emittance growth due to Power Converter Ripple and Noise at 50 Hz harmonics during LHC collisions

Transverse emittance growth can adversely affect the luminosity production performance of colliders such as the Large Hadron Collider (LHC) at CERN. While Intra-Beam Scattering (IBS) and Synchrotron Radiation (SR) effects represent important ingredients for the emittance evolution, measurements in the LHC do not match predictions from these two effects, suggesting the presence of additional emittance growth mechanisms. External excitations, such as power supply ripple and noise at 50 Hz harmonics, are additional sources of emittance growth especially in the presence of non-linearities as induced by beam-beam effects. In the LHC, the most prominent excitations during collisions are harmonics of 50 Hz clustered around 8 kHz. In this work, we quantify the expected contribution of these excitations to the emittance evolution and proton losses using single particle tracking simulations including a realistic excitation spectrum as observed in operation.

Speaker: Anna Radoslavova (European Organization for Nuclear Research, Goethe University Frankfurt)

14:00 Emittance measurement of the CERN antimatter beam for the GBAR experiment

On behalf of the GBAR collaboration

The GBAR (Gravitational Behavior of Antihydrogen at Rest) experiment receives particle beams from the AD/ELENA facility at CERN, the world's unique source of low-energy antiprotons.The AD/ELENA facility is also unique in its deceleration of GeV beams created using CERN proton-synchroton (PS) machine. * According to the 2023 review, the beam delivered by AD/ELENA to users now benefits from improved stability and quality. **

Unlike most of the AD experiments, GBAR uses a pulsed drift-tube scheme to electrostatically decelerate the ELENA antiproton pulses from 100 keV, to as low as 1 keV, for injection into a Penning trap for cooling and accumulation. This makes GBAR very sensitive to the emittance of the ELENA beam.

Using a uni-potential lens in a variant of the quadrupole scanning technique, we present emittance measurements of the ELENA antiproton pulses using phosphor-screen images of a multichannel-plate detector. Complementary measurements were performed with matter-analog H$^{-}$ pulses, also provided by ELENA but using a duo-plasmatron source at 100 keV. The emittances are compared to quantify differences in machine performance and to study the MCP detector response to antimatter.

Speaker: Sarah GEFFROY (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

14:00 Enhanced coherent terahertz generation in storage rings with an active demodulation section

Coherent terahertz (THz) radiation sources based on storage rings hold significant future for generating high-average-power THz radiation, owing to the high revolution frequency of the electron beam. However, the achievable repetition rate is limited by the long time required for the ring's damping mechanism to dissipate the phase-space perturbation introduced by the modulation and radiation process. To overcome this bottleneck, we propose a novel scheme that incorporates a dedicated demodulation section to enhance the generation of high-repetition-rate coherent THz radiation. In this scheme, after a seed laser imposes a density modulation and a THz wiggler emits coherent radiation, the electron beam is actively cooled in the demodulation section. This process facilitates the beam's rapid recovery, allowing it to be effectively damped and ultimately reach a new steady state. Simulation results demonstrate that this integrated setup successfully produces coherent THz radiation pulses at a repetition rate of 100 kHz, achieving an average power of 6.2 mW at 10 THz.

Speaker: Xiazhen Xu (University of Science and Technology of China)

14:00 Enhanced superconducting properties of Nb films via a high-power impulse magnetron re-sputtering/sputtering approach for Nb–Cu 1.3 GHz RF cavities

Conformal deposition of high-performance superconducting films on complex cavity geometries, particularly ensuring robust film-substrate adhesion, remains a fundamental challenge. We address this by introducing a novel high-power impulse magnetron re-sputtering and sputtering (HiPIMRS) system designed for uniform niobium (Nb) film deposition on the interior surfaces of 1.3 GHz copper cavities. A key innovation is an in-situ copper substrate re-sputtering step prior to Nb deposition, which eliminates interfacial oxides and degradation, ensuring atomic-scale interfacial integrity. Through in-situ re-sputtering prior to deposition, we achieve oxide-free Nb/Cu interfaces with atomic-scale integrity. Crucially, electrical transport measurements demonstrate a significant enhancement in the superconducting transition temperature from 8.5 K to 9.3 K for HiPIMRS films, along with smooth surfaces (Rₐ < 20 nm) and a preferred (110) orientation. This work establishes HiPIMRS as a viable pathway for next-generation superconducting radiofrequency (SRF) cavity production, with its interfacial engineering protocols offering significant advancements in film conformity and superconducting properties.

Speaker: JianJun XIAO (ShanghaiTech Laboratory for Topological Physics, School of Physical Science and Technology, ShanghaiTech University, State Key Laboratory of Quantum Functional Materials, School of Physical Science and Technology, ShanghaiTech University)

14:00 Evaluation and Mitigation of Residual Magnetic Field from the High-Voltage Pulse Power Supply for the Beam Kicker in the Muon g-2/EDM Experiment

In the J-PARC muon g-2/EDM experiment, precise control of the muon beam is essential to achieve the required measurement accuracy. For this purpose, the development of a new high-voltage and high-current pulse power supply(kicker power supply) is indispensable. Because the accuracy of the g-2 measurement strongly depends on the uniformity of the magnetic field, and the muon beam must remain confined within a region of 10 cm in height and a radius of 33.3 cm, any residual magnetic field leads to a degradation of the precision. While the design of the static magnetic field is being developed to meet the experimental requirements, the residual dynamic magnetic field remains a challenge. In this study, aiming to develop a power supply that satisfies the required precision, we evaluated the impact of the residual magnetic field caused by the kicker power supply on the measurement accuracy. This presentation will report the results of the evaluation and our efforts to reduce the residual magnetic field.

Speaker: Yuta Kawase (Iwate University)

14:00 Evaluation of the performances of a Non-Linear Kicker injection scheme at the European Synchrotron Radiation Facility

In the scope of the upgrade of its injection systems, the European Synchrotron Radiation Facility - Extremely Brilliant Source (ESRF-EBS) has decided to replace the classical 4-kicker bumps injection scheme by a Non-Linear Kickers (NLK) injection scheme in order to achieve a fully transparent injection into the storage ring and minimize the perturbations still seen by the beamlines users. This paper presents beam dynamics simulations evaluating the performance of this new scheme including robustness against errors from the transfer line pulsed elements between the booster synchrotron and the storage ring, optics mismatch and compensation of the non-linear kicker field using a sextupole magnet to improve efficiency in realistic operation conditions. Benefits from a booster light upgrade and full energy linac upgrade will also be presented.

Speaker: Antonin Sauret (European Synchrotron Radiation Facility)

14:00 Experimental and First-Principles GGA-PBE Insights into SHI-Induced Defects and Local Bonding Among Different Grain Sizes in Ce₀.₇₅Gd₀.₂₅O₂

To evaluate radiation tolerance, 25 mol% Gd₂O₃-doped CeO₂ nano powders were synthesized by a sol-gel combustion route and sintered at 800°C, 1000°C, and 1300°C to obtain different grain sizes. The pellets were irradiated with 100 MeV iodine ions to simulate fission-fragment damage, and structural and electronic changes were examined using synchrotron GIXRD, Raman spectroscopy, EXAFS, XPS, and electron microscopy. Smaller grain-sized samples (800°C) exhibited more significant irradiation-induced degradation compared to larger grain-sized samples (1300°C), although both maintained their fluorite cubic structure at the highest ion fluence (1×10¹⁴ ions/cm²). EXAFS indicated Ce–O bond relaxation, Gd-coordination changes, and redistribution of oxygen vacancies. Raman peak broadening suggested vacancy-related defect complexes, and XPS revealed shifts in Ce³⁺/Ce⁴⁺ ratios and charge redistribution. First-principles GGA-PBE calculations support vacancy stabilization and local bonding rearrangement. The results highlight clear grain-size-dependent radiation response in Gd-doped CeO₂ and its relevance for nuclear and space applications.

Speaker: VIVEK KUMAR (Jawaharlal Nehru University)

14:00 Experimental Design for Validating Relativistic Ponderomotive Dynamics via Laser Modulation of MeV Electron Beams

We present a design for the experimental validation of relativistic ponderomotive dynamics on a realistic MeV electron-beam platform. The scheme combines an S-band gun with a co-propagating focused laser pulse to induce longitudinal momentum modulation in relativistic electrons. Using a nonparaxial laser-field model and beam-dynamics simulations, we evaluate the expected post-interaction energy signatures and their observability on a practical beamline. Particular attention is given to the dependence of the modulation on laser focusing, beam parameters, and synchronization errors. The analysis identifies the dominant force contributions governing the final energy distribution. These results provide a practical route for translating previously derived relativistic ponderomotive theory into a testable experiment.

Speaker: Mr Jinming Zhang (National Synchrotron Radiation Laboratory, University of Science and Technology of China)

14:00 Experimental investigation of injector halo for PERLE using scaled measurements at cERL

The PERLE (Powerful Energy Recovery Linac for Experiments) project requires an injector which is capable of delivering a high-current, high-bunch-charge electron beam. Therefore, a key challenge is controlling the effects of space charge forces and the subsequent formation of halo. Beam dynamics simulations of the PERLE injector predict the onset of transverse halo due to a strong space charge effect at low energy, but experimental validation of these effects remains limited. In this work, we present an experimental study aimed at benchmarking and supporting PERLE injector halo studies using measured data from the compact Energy Recovery Linac (cERL) at KEK as a representative low-energy ERL testbed. Measurements were performed at beam energies around 3 MeV and bunch charges up to 100 pC. Transverse beam profiles were recorded at several screens downstream of the booster and through the dispersive merger section. High dynamic range imaging techniques are used to characterise the halo and study its sensitivity to injector tuning. We support these experimental results with simulations of both the cERL and PERLE injectors under scaled space-charge conditions. The combined experimental and numerical study provides insight into the halo formation mechanisms at high-charge. The results here support the development of the PERLE injector optimisation and halo mitigation strategies.

Speaker: Connor Monaghan (University of Liverpool)

14:00 Experimental Measurement of Wakefield Dephasing During Proton Bunch Self-Modulation.

Dephasing between the driver and witness is one of the main mechanisms limiting witness energy gain in plasma acceleration. We show time-resolved, picosecond-scale measurements of the self-modulating proton driver in AWAKE (Advanced WAKefield Experiment at CERN) as a function of plasma length, revealing the evolution of this drive bunch caused by transverse wakefield development and dephasing. Comparison with numerical simulations allows us to establish a correspondence between the modulated bunch distribution and the wakefields, which cannot be directly measured. Analysis of the bunch train confirms that the wakefield phase velocity is slower than the proton velocity, in agreement with simulations. Analysis of the bunch train evolution confirms that the wakefield phase velocity during self modulation in uniform plasma is lower than the proton velocity, as previously predicted. We further show that the wakefield phase velocity can be controlled through the plasma density profile, with negative and positive density gradients leading to a decrease and increase in phase velocity respectively.

Speaker: Helena Jaworska (Heinrich Heine University Düsseldorf)

14:00 Experimental Reconstruction of Source 4D Phase Space Without Prior Knowledge of Transfer Matrix

We use the PHOEBE test beamline at Cornell to experimentally demonstrate a simple method for reconstructing the transverse 4D phase space of an electron beam at the source from downstream aperture scans of the beam. This method does not rely on detailed knowledge of the beamline transport, besides assuming that linearity and symplecticity are satisfied. We apply this method to measure the source 4D phase space of electrons emitted from a spatially-structured alkali-antimonide cathode, and verify the fidelity of the reconstructed source spatial and momentum distributions.

Speaker: Charles Zhang (Cornell University (CLASSE))

14:00 Experimental Validation of an Additively Manufactured 1.3 GHz Radio Frequency Cavity

A compact continuous-wave (CW) 1.3GHz linear par
ticle accelerator (linac) is currently under development as
the core component of a high energy positron annihilation
lifetime spectroscopy setup. The associated thermal load
imposes stringent requirements on the design and manu
facturing of the underlying multi-cell radio-frequency (RF)
cavity. Metal-based laser powder bed fusion (PBF-LB/M)
has recently demonstrated the capability to fabricate pure
copperRFcavitiesasmonolithiccomponentswithintegrated
complex geometries, such as cooling channels. In this work,
we present and evaluate a first 1.3GHz single-cell RF cavity
as a prototype for the intended multi-cell structure, manufac
tured from pure copper using PBF-LB/M. Helium leak rate
and low-level RF measurements meet the linac expectations.
While the dimensional accuracy is reduced compared to con
ventional manufacturing approaches, it can be compensated
by an iterative design approach. These results demonstrate,
for the first time, the feasibility of PBF-LB/M as a manufac
turing route for monolithic 1.3GHz RF cavities.

Speaker: Mr Hermann Winter (Universität der Bundeswehr München)

14:00 Exploring the Asymmetric Momentum Acceptance at the CERN Super Proton Synchrotron

Studies conducted at CERN's Super Proton Synchrotron (SPS) in 2017 showed an asymmetric off-momentum acceptance for Q20 optics. A systematic mechanical limitation near the defocussing quadrupoles -- the most restrictive regions of the ring in the Q20 optics -- was suggested as a possible explanation for this asymmetry and was addressed during LS2. However, improvements were only observed in some of those locations. This paper aims to revisit this topic to identify potential bottlenecks and their causes. Additionally, some regions are more limiting than others despite having the same linear optics, which could be explained by aperture shifts, orbit misalignments, non-linear contributions of the lattice, or any combination of those. Measurements were performed at different locations by introducing orbit bumps and changing the frequency of the RF cavities, in order to identify the dominant bottleneck regions. In parallel, simulations were conducted to predict the location of the primary bottleneck and to reproduce the experimental data.

Speaker: Lise Pauwels (European Organization for Nuclear Research, Université Libre de Bruxelles)

14:00 Femtosecond-Micron Resolution Electron Bunch Diagnostics via Laser-Drilled Diamond X-ray Optics

We report a technique for fabricating optically transparent x-ray optics by laser drilling precision pinholes in diamond membranes. This work supports a novel diagnostic under development at SLAC which will profile the Coulomb field of relativistic electron bunches with femtosecond-um spatio-temportal resolution.

Diamond is chosen for its specific transmission window extending from RF through UV (relevant for preserving the space charge field of the electron bunch). It is also very robust, however, thin free-standing diamond is challenging to process. In this proceedings, we describe a laser drilling setup with integrated laser-profiling measurements capable of generating <30um holes in 2um thick, 2mm diameter diamond membranes. A Ti:Sapphire laser was focused on the membrane, mounted on a three-axis positioning system. A python code automatically performs knife edge scans of the gaussian intensity profile to plot the waist at multiple z positions, mapping the complete waist profile versus propagation distance. The membrane is then positioned at the z location of the desired hole diameter, and the laser power is increased past the ablation limit to create a precisely sized pinhole at the target location.

This technique enables cnc fabrication with micron accuracy without requiring complex lithography or mechanical drilling, and is broadly applicable to precision micro-machining of thin, brittle substrates.

Speaker: Sean OTool (Stanford University)

14:00 Final Focus Systems at 550 and 1500 GeV

The Final Focus System (FFS) results for CLIC at 1.5 TeV have thus far been estimated using a 3 TeV system operated at reduced energy. Here, we present a dedicated design for the 1.5 TeV stage, where we exploit reduced radiation effects to allow stronger dispersion and weaker chromaticity-correcting sextupoles, thereby mitigating beam transport nonlinearities. The performance of both normal-conducting and superconducting beams at 550 GeV are evaluated using the CLIC FFS, addressing the goals defined by the CLIC and Linear Collider Facility at CERN inputs to the European Strategy for Particle Physics Update.

Speaker: Lewis Kennedy (John Adams Institute for Accelerator Science, University of Oxford, European Organization for Nuclear Research)

14:00 First direct observation of a wakefield generated with structured light

Since their inception, laser-wakefield accelerators (LWFAs) have shown their capability to produce high-quality, monoenergetic electron beams. Yet, the push toward higher electron energies and more efficient accelerators is constrained by several limitations. Foremost among these are the dephasing and diffraction limits. A promising strategy to address these issues involves using structured light to modulate the on-axis propagation velocity in LWFAs. By pairing the diffraction-resistant properties of Bessel beams with spatio-temporal pulse shaping, this approach offers an unprecedented combination of extended acceleration lengths and strong acceleration gradients.

Here we present the first experimental observation of wakefields driven by such structured beams. Spatio-temporally tailored pulses are directed through a specialized focusing mirror to form a quasi-Bessel beam, and the resulting wakefield is directly probed using femtosecond relativistic electron microscopy. Simulations corroborate the experimental data, offering novel insights into this underexplored regime. We show an experimental demonstration of the ability to modify the on-axis propagation velocity of the wakefield. We track the wakefield’s evolution throughout the focal region and examine how specific spatio-temporal manipulations influence both its structure and propagation velocity. Finally, we present the first results using such wakefields to accelerate electrons. These findings establish a foundation for harnessing structured-light-based strategies to overcome dephasing in LWFA.

[1] A. Liberman et al., “Direct Observation of a Wakefield Generated with Structured Light,” Nature Communications, Accepted. (https://arxiv.org/abs/2503.01516)
[2] A. Liberman et al., “First Electron Acceleration in a Tunable-Velocity Laser Wakefield,” under review. (https://arxiv.org/abs/2509.21098)
[3] A. Liberman et al., “Probing Flying-Focus Wakefields,” under review. (https://arxiv.org/abs/2510.16950)
[4] A. Liberman et al., "Use of spatiotemporal couplings and an axiparabola to control the velocity of peak intensity," Opt. Lett. 49, 814-817 (2024)

Speaker: Aaron Liberman (Weizmann Institute of Science)

14:00 FLUKA-Based Optimization of Pion Production for a Muon Collider Demonstrator

This study uses FLUKA simulations to investigate pion production from proton interactions with a graphite target for muon collider applications. A 40 cm target is struck with 0.8 GeV and 8 GeV/c proton beams, and pion yields are evaluated in terms of angular and energy distributions. The dependence of pion yield on target length is also examined, showing saturation near one interaction length for the 0.8 GeV beam, and saturation near two interaction lengths for the 8 GeV/c beam due to secondary interactions. In addition to total production, a subset of “acceptable” pions is defined based on capture constraints (kinetic energy <400 MeV, forward-going, and escaping the target). The results show that while the 8 GeV/c beam produces higher overall yields, the 0.8 GeV beam provides a larger fraction of pions within the desired constraints. Charge asymmetry is also observed in pion production, with implications for muon beam balance and collider luminosity.

Speaker: Ruaa Alharthy (University of Wisconsin–Madison)

14:00 Gaussian Process Regression and Bayesian Optimization for a 40-90 MeV Laser-Plasma Injector for the cSTART Storage Ring

Laser-plasma accelerators (LPAs) generate ultrashort high intensity electron bunches from a compact source size. At the Karlsruhe Institute of Technology (KIT), we will use an LPA as one of the injectors for the compact, high-momentum acceptance, non-equilibrium storage ring cSTART.

The LPA injector with a length of only a few millimeters will be optimized to match the cSTART operation beam energy of 40-90 MeV. It will be based on an ionization trapping scheme in combination with a tailored plasma density profile to produce an electron beam with small energy spread that maximizes the spectral charge density at our target energy, which is (for LPAs) comparably low. Moreover, the LPA injector must produce controlled electron beams with high shot-to-shot stability and avoid high-energy tails. These goals can be achieved largely by the detailed design of the plasma density profile and the laser pulse parameters.

In an LPA, small changes across the high-dimensional parameter space can have a disproportional influence on overall performance. To find parameters for stable high-quality LPA beams, we perform particle-in-cell (PIC) simulations and implement a machine-learning driven approach by using Bayesian Optimization (BO) based on Gaussian Process Regression (GPR). This procedure allows us to both optimize our gas target design and characterize the effects of the interaction parameters, giving us a functional LPA with a simple tuning mechanism.

Speaker: David Squires (Karlsruhe Institute of Technology)

14:00 GPU-Accelerated Simulation Framework for Partially Coherent EUV Light Transport in Tsinghua SSMB Beamline Optics

Accurate simulation of partially coherent beam transport and coherence evolution is critical for next-generation accelerator-based light sources. In this work, we develop a dedicated numerical approach for partially coherent EUV beamline propagation to support the optical design and optimization of Steady-State Microbunching (SSMB) beamlines under development at Tsinghua University.* A GPU-accelerated mutual optical intensity framework is developed for two-dimensional propagation of partially coherent radiation. Using spatially partitioned diffraction-integral kernels with locally reconstructed paraxial approximation, the method achieves substantial speedup over conventional mutual-intensity and wavefront-based propagation methods while maintaining high accuracy. Complex optical components, including arbitrary curved and rough reflective surfaces, are fully supported for efficient simulation of realistic EUV systems. In summary, the proposed framework provides a practical tool for optical design and end-to-end simulation of EUV beamlines, enabling coherence analysis and accurate light propagation modeling of partially coherent radiation.

Speaker: Mr Haowei Hu (Tsinghua University)

14:00 Gradient-based laser control for end-to-end photoinjector emittance optimization at EuXFEL

Achieving low emittance at the photoinjector is essential for meeting the performance targets of the European XFEL, particularly for high photon energies and future high-duty-cycle operation. Both the temporal structure of the drive-laser pulse and the RF-gun settings contribute significantly to the final beam quality, yet their optimization is complicated by strong nonlinearities in the laser system and complex gun response. We have developed a differentiable, physics-based model of NEPAL, the photoinjector laser of EuXFEL, that enables gradient-driven optimization of the temporal UV pulse shape. The model captures the relevant nonlinearities of the optical chain and allows direct optimization of spectral amplitude and phase to obtain target UV profiles at the photocathode. In parallel, a machine-learning surrogate model is being implemented to optimize the RF-gun operating parameters. Together, these tools provide an end-to-end control framework for emittance reduction at EuXFEL. Initial results demonstrate that the differentiable model enables accurate temporal UV pulse shaping at EuXFEL. Work is ongoing to integrate this approach with ML-assisted gun optimization within the proposed end-to-end control framework.

Speaker: Denis Ilia (Deutsches Elektronen-Synchrotron DESY, Universität Hamburg)

14:00 Growth and Evaluation of High QE Semiconductor Photocathodes for High-Brightness Electron Sources

Alkali–antimonide photocathodes are promising candidates for high-brightness electron sources due to their combination of high quantum efficiency (QE) in the visible range and intrinsically low mean transverse energy (MTE). In this work, we present ongoing R&D aimed at understanding and optimizing their growth and performance. Using an ultra-high-vacuum (UHV) preparation and transfer system, we grow and characterize a range of alkali metal-based high QE compounds. The photocathodes are tested in situ in a high-gradient DC electron gun immediately after growth, allowing direct correlation between growth parameters, surface properties, and field emission performance. The results provide comparative insights into alkali–antimonide and telluride photocathodes, highlighting the trade-offs between QE, robustness, and brightness, and guiding further optimization of high-brightness electron sources for accelerator applications.

Speaker: Peter Owusu (Arizona State University)

14:00 Halo cleaning and collimator optimization at PERLE

PERLE (Powerful Energy Recovery Linac for Experiments) is a multi-turn, high-current energy-recovery linac under development at IJCLab, designed to operate at 20~mA and 250~MeV.
To limit beam-induced losses in downstream superconducting sections, halo particles must be intercepted at low energy.
In this work, halo cleaning in the merger is studied using a 6D particle distribution obtained after the booster stage, at 7~MeV.
The beam phase-space evolution is analyzed to identify optimal locations for one or two collimators.
Particle tracking simulations performed with the Bmad code are used to validate the collimation strategy and quantify its efficiency.
Despite the low dispersion in the merger, correlations between transverse and off-momentum halo enable partial removal of off-momentum particles.
The sensitivity of the collimation efficiency to booster cavity misalignments is also investigated.

Speaker: Arnaud CIEPLAK (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

14:00 High-power experimental study on a compact C-band spherical pulse compressor

In order to enhance the accelerating gradient of the 1-meter C-band Traveling-wave accelerating structure prototype, as well as meet the physics requirements on the linear injector of the proposed Jinhua light source (JHLS) project, a compact C-band spherical pulse compressor was developed to boost the output power from klystron. This pulse compressor excites TE114 modes inside the spherical cavity by coupling energy via a compact polarized coupler. In the preliminary high-power conditioning, an output pulse of 8.7 MW, 2.6 μs from the klystron was compressed to 53.9 MW, 400 ns pulse through this pulse compressor, thereby enabling an average power gain of 4.2. An amplitude modulation approach was adopted to generate a flattop output pulse, an average power gain of 3.78 with a full-width at half-maximum (FWHM) pulse duration of 353 ns was achieved after modulation.

Speaker: Zexin Cao (University of Science and Technology of China)

14:00 High-power Test of a 40kW Industrial Electronic Linear Accelerator

Electron accelerators with high average power output are widely used in radiation processing fields such as material modification, food sterilization, and environmental pollutant treatment. This paper presents a comprehensive high-power test of a 40kW electron accelerator. Key parameters including electron beam energy, average beam current, output power, and pulse characteristics were measured. The results show that the accelerator’s electron beam energy, the average beam current, and the effective output power all meet the design specifications. The energy test was performed via the aluminum foil stacking method, ensuring high measurement accuracy. This study validates the reliability and stability of the accelerator, providing technical support for its industrial application.

Speaker: Yan Zhao (Tsinghua University)

14:00 Hollow Bunch Method for Improved Spot Dose Accuracy in 3D PBS Proton FLASH

A longitudinal localized kick-driven fast extraction technique has been employed to enable three-dimensional (3D) proton pencil beam scanning (PBS) at ultra-high dose rate (FLASH) for large-volume targets. However, it was observed that the longitudinal line density of the proton bunch significantly influences spot dose accuracy. In this study, a hollow bunch method—implemented by using two harmonic waves to manipulate the longitudinal phase space—is applied to reduce the line density in the extraction region. The RF parameters are carefully chosen so that the evolution of the phase space satisfies the requirements. Simulations conducted with the SynTrack code demonstrate that this method can effectively reduce the line density in the extraction region, thereby offering the potential to improve spot dose accuracy.

Speaker: Yang Xiong (Key Laboratory of Particle & Radiation Imaging (Tsinghua University), Ministry of Education, Beijing, China, Laboratory for Advanced Radiation Sources and Application, Tsinghua University, Beijing, China, Department of Engineering Physics, Tsinghua University, Beijing, China)

14:00 Hybrid optimisation of THz-driven tapered waveguides for synchronous acceleration of weakly relativistic high-quality electron bunches

Downscaling particle accelerators is crucial to expanding their range of applications. Dielectric-lined waveguides (DLWs) can support hybrid modes with a strong accelerating component. Excited by terahertz (THz) frequency pulses, DLWs can deliver high accelerating gradients over cm-scale interaction lengths, promising the development of future compact electron accelerators. By precisely tailoring the waveguide geometry, the modal field profile and phase velocities can be tuned to maintain synchronisation between the weakly relativistic bunches and the accelerating mode over extended distances. Here, we design and evaluate THz-driven tapered DLWs delivering high-quality, MeV-level electron bunches in two types of symmetrical DLW waveguides: rectangular and cylindrical. The hybrid optimisation process is presented here based on an analytic model of accelerating modes in DLW and on detailed particle-in-cell simulations. We simulate transport and acceleration of an externally injected 100 keV electron beam for various DLW geometries. A genetic algorithm is employed to identify Pareto-optimal geometries based on final bunch qualities such as emittance, energy spread, and charge.

Speaker: Filip Peczek (University of Manchester, Cockcroft Institute)

14:00 IFMIF-DONES Beam on Target Diagnostics based on Optical Methods: OTR and Fluorescence

The IFMIF-DONES facility located at Escúzar in Spain will consist of an accelerator delivering 125 mA of 40 MeV deuterons onto a liquid lithium target. The beam profile at the target will have a rectangular footprint with two side peaks to satisfy the irradiation requirements. The environment conditions are characterized by a high radiation background and the presence of lithium vapor. Additionally, deuteron scattering with residual gas and secondary-electron production occur. To measure the footprint under these conditions optical methods are designed based either on measuring Optical Transition Radiation (OTR) of the beam passing through the liquid lithium or on the Beam Induced Fluorescence (BIF) of the residual gas in the proximity of the liquid lithium. Both alternatives have its advantages and drawbacks. In this paper it is described the pros and cons of both alternatives. Furthermore, an experiment to better characterise the OTR response in liquid lithium is also presented.

Speaker: Jorge Herranz (IFMIF-DONES España, Universidad de Granada)

14:00 Impact of a quasi-resonant AC dipole excitation on transverse beam splitting

For multi-turn extraction at the CERN Proton Synchrotron, the beam is transversally split into five separate beamlets. It has been shown that an AC dipole excitation effectively controls the characteristics of these beamlets. For this purpose, the AC dipole is set in resonance with the horizontal betatron tune while the horizontal tune crosses the 4th-order resonance, creating a double-resonance condition, i.e. the simultaneous resonance between the horizontal tune and the AC dipole excitation. This increases the fraction of particles that are moved from the core to the islands. Further studies have revealed that shifting the AC dipole tune slightly, thereby breaking the double-resonance condition, distributes the beam more evenly across the beamlets. This paper examines this phenomenon by establishing a Hamiltonian model for a system with such a quasi-resonant AC dipole and studying it with numerical simulations.

Speaker: Oleksandr Naumenko (European Organization for Nuclear Research)

14:00 Impact of Initial Energy Spread on the Accuracy of Energy Spread Growth Formula in a FREE Electron laser

Evaluating the energy spread growth due to radiation is crucial for the design of steady-state microbunching (SSMB) insertion section. This study systematically benchmarks a classical analytical formula against three-dimensional numerical simulations to validate its accuracy under varying initial energy spreads. Our findings reveal that while the formula provides reliable estimations for beams with small initial energy spreads, its predictions deviate significantly as the initial energy spread increases. Such discrepancies arise because larger initial energy spreads amplify three-dimensional effects and nonlinear beam dynamics, which compromise the idealized analytical model. This study shows that comprehensive 3D simulations are indispensable for robust and accurate SSMB insertion section design.

Speaker: Weihong Huang (Tsinghua University)

14:00 Impact of Injection Error on EUV FEL Performance in an APL-based Beamline

Recent advances in laser-plasma accelerators (LPAs) have generated high-quality electron beams characterised by high peak currents and low emittance, making them suitable for powering compact, next-generation free electron lasers (FELs). However, variations in laser performance from shot to shot cause mismatches in position and angle at the injection point, complicating efficient beam transport and stable FEL operation. To preserve the electron bunch quality during beam propagation through a specialised, compact transport system, an active plasma lens (APL) can be used as part of the capture mechanism.

This report investigates how injection errors influence electron beam properties along the beamline and their subsequent effect on FEL radiation in the extreme-ultraviolet (EUV) range.

The results demonstrate an acceptable range of injection errors, including the mismatching effect, and emphasise the strengths and limitations of APLs as capture systems for optimal FEL performance. Various correction methods are analysed to minimise the impact of these injection errors.

This work emphasises the potential of APL technology to develop compact FELs and improve LPA beam applications. Such progress is vital for future FEL facilities at ELI ERIC in the Czech Republic and for the EuPRAXIA project.

Speaker: Mihail Miceski (Extreme Light Infrastructure Beamlines, Czech Technical University in Prague)

14:00 Impact of Intrabeam Scattering and Space-Charge in the First Three Cells of the Muon Collider Final Cooling Channel

The cooling process is one of the most critical challenges for the future Muon Collider, as muons are initially produced with a very large emittance that must be significantly reduced before acceleration. This cooling must occur rapidly, well within the muon lifetime. At low energies, collective effects such as space charge and intrabeam scattering can strongly influence emittance growth and must therefore be considered in the lattice design, which is currently under development. This work presents studies of space charge and intrabeam scattering effects in the first three cells of the latest Muon Collider final cooling lattice design, evaluating their impact on emittance growth using the tracking code RF-Track.

Speaker: Paula Desire Valdor (European Organization for Nuclear Research, University of Groningen)

14:00 Impact of Rapid Acceleration on Beam Dynamics in the Rapid-Cycling Synchrotrons of a Muon Collider

Circular muon colliders offer a promising route to multi-TeV center-of-mass energies with high luminosity. The baseline design for the high-energy complex includes a chain of pulsed synchrotrons covering energies from 63 GeV to 5 TeV. This chain combines normal and hybrid synchrotrons, using both fixed-field superconducting and pulsed normal-conducting magnets. The short muon lifetime (2.2 microseconds in the rest frame) constitutes a major challenge for the accelerator complex: attaining high luminosity requires a muon survival rate of up to 70 % throughout the acceleration chain, implying acceleration within a few milliseconds. Such rapid acceleration causes a mismatch between the beam energy in the arcs and the linearly ramped fields of the dipoles and quadrupoles. The corresponding field errors affect both the beam trajectory and optical functions. Preliminary tracking studies have been conducted to assess the emittance growth arising from these effects.

Speaker: Lisa Soubirou (Université Paris-Saclay)

14:00 Impact of Wiggler Field Profiles on Key Beam Parameters in the STCF

The Super Tau-Charm Facility (STCF), a next-generation high-luminosity frontier collider, adopts a large crossing angle with the Crab-Waist scheme to enhanced collision luminosity. The center-of-mass energy range of STCF is 2-7 GeV, and the designed collision luminosity will exceed $0.5 \times 10^{-35} \, \text{cm}^{-2} \text{s}^{-1}$. The STCF’s collider rings are two high-current, low-emittance electron and positron storage rings operating over a wide energy range. However, synchrotron radiation damping from lattice alone is inadequate to achieve the desired short damping time, low horizontal emittance, and relatively high beam energy spread. To address this, the damping wigglers are incorporated into the rings to enhance damping effects.
This study finds that the longitudinal magnetic field distribution $B_{y}(s)$ in practical damping wigglers often deviates from the ideal sinusoidal curve. Particularly for damping wigglers with large period lengths, the field profile near the peak approaches a flat-top shape, which differs significantly from a sinusoidal curve. To better represent such field distributions, a trapezoidal field model was developed with the definition of a rectangularity parameter $k$. Based on this model, analytical formulas for synchrotron radiation integrals and beam parameters under the trapezoidal field approximation have been derived, enabling further parameter optimization of the damping wigglers in the STCF collider rings.

Speaker: Hangzhou Li (University of Science and Technology of China)

14:00 Implementation of multi energy extraction configurations at MedAustron

Moving from extracting one single energy per cycle to multiple energies promises improvements in time and power budgets of medical synchrotrons. To ensure reproducible and accurate beams for treatment, hysteresis effects must be considered. To avoid losses during energy changes, the beam has to be moved away from the extraction resonance. Four different methods of moving the working point were compared regarding their robustness, adaptability and speed by means of measurements and Xsuite simulations. The measurements were taken at the synchrotron facility MedAustron. The four methods are devised for the PIMMS based lattice with one resonant sextupole and off-momentum operation, and differ in how the working point is shifted during the energy change regarding the timing of element ramps and off-momentum contributions.

Speaker: Katrin Holzfeind (TU Wien)

14:00 Implications of Degenerate Mode Mixing in UK XFEL SC Cavities

The UK XFEL (United Kingdom X-ray Free Electron Laser) is a proposed accelerator facility that will use predominantly superconducting RF structures to accelerate and manipulate the transiting electron bunches. Deviations from design longitudinal length of these Niobium RF cavities, or cells within, caused by errors in manufacturing, fabrication tolerances, assembly and installation can lead to certain modes becoming frequency degenerate. This gives rise to mode mixing, whereby the component modes combine to form additive and subtractive field distributions. Here we look at the mixing of transverse magnetic (TM) modes and locate problematic combinations where field strength enhancements can lead to increased on-axis loss factors and dipole kick factors, both of which can have adverse effects on the beam emittance and energy.

Speaker: Anthony Gilfellon (Cockcroft Institute)

14:00 Improving Energy Spread of MESA Beam in ERL Operation

MESA, the Mainz Energy-Recovery Superconducting Accelerator, currently under commissioning at Johannes Gutenberg University Mainz, is designed to operate in two modes: external beam (EB) mode, with 150 μA polarized electrons at 155 MeV serving the P2 experiment, and energy-recovery linac (ERL) mode, with an unpolarized beam of 1–10 mA at up to 105 MeV for the MAGIX experiment. The latter requires precise control of the energy spread and the bunch length across various beam energies of 30, 55, 80, and 105 MeV. Comprehensive simulations were conducted using the tracking code ELEGANT; starting with a 4-ps bunch length, the full acceleration and deceleration process in ERL mode was modeled by optimizing the RF phase and the accelerating gradient field in off-crest operation, which results in the desired energy gain in each linac section. To reach the lowest energy spread, an appropriately selected longitudinal dispersion in the recirculation arcs is required. Since the beam is more sensitive to RF curvature and space-charge effects at low energies, reducing the bunch length by 50 % results in a small energy spread. Consequently, the injection arc lattice is optimized by adjusting the arc momentum compaction R56 as the primary tuning parameter. The integration of a chirp and R56 tuning enables efficient, controlled bunch compression and thereby enhances the overall beam quality.

Speaker: Mrs Esraa Khidr (Johannes Gutenberg University Mainz)

14:00 Improving Injection at Diamond using Dimensionality Reduction Techniques and Bayesian Optimisation

Injection efficiency into the Diamond Light Source Storage Ring (SR) is currently optimised by operators performing a grid scan over the final pair of corrector magnets inside the Booster-to-Storage Ring (BTS) transfer line. The phase advance between the pair is sufficient to provide good control over the position and angle of the beam as it enters the SR. However, the method is slow and the strengths of the corrector pair can approach power supply limits over time as machine conditions drift. We propose a Bayesian optimisation algorithm to optimise leading right-singular vector coefficients obtained from a Singular Value Decomposition (SVD) of the BTS response matrix over all corrector magnets, improving sample efficiency. We further transform the proposed coefficients through a non-linear map to restrict the set of solutions to a desirable range as determined by the user. We compare our results to the grid scan technique and suggest further refinements to the algorithm.

Speaker: Shaun Preston (University of Oxford, John Adams Institute for Accelerator Science, Diamond Light Source)

14:00 In-situ XPS study of Nb surface during mid-T bake with plasma treatment for SRF cavities

Specific heat treatments applied to superconducting radio-frequency (SRF) cavities, such as nitrogen infusion or Mid-T baking, aim to improve the quality factor (Qo) at medium accelerating fields (˜10–20 MV/m). These treatments reduce the BCS surface resistance by tuning the mean free path of niobium over a few hundred nanometers, either by diffusing oxygen from the native oxide layer or by diffusing nitrogen after the dissolution of the oxide layer. However, these treatments preclude the usual chemical polishing, as it would reverse the beneficial effects of the heat treatments, making the cavities highly sensitive to surface contamination. In particular, the formation of niobium carbides, which can mask the expected benefits, strongly depends on the annealing conditions, surface preparation, and the material’s history.

To better understand these phenomena, niobium samples was annealed under ultrahigh vacuum (Mid-T baking) with plasma treatment to investigate surface contamination with in-situ heat treatment and XPS analysis.

Speaker: Chahinez Boutelaa (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

14:00 Initial beam characterization from a cold field emitter in a VHF electron gun

High-quality electron beams are critical for imaging experiments that provide detailed microscopic structural insights into materials. The Very-High-Frequency electron gun, capable of operating in continuous and pulsed modes, is a preferable option. In this paper, we employ a tungsten tip with an apex radius of curvature approximately 100nm as a cold field emission cathode in the VHF gun and measure the beam charge, transverse emittance, and energy spread to characterize the beam quality. In preliminary experiments, we have achieved a normalized transverse emittance of 54.01nm·rad. With an electron gun power of 37kW, we obtained astrongbeamcurrentofapproximately 6µA, which remained stable and continuous for several hours in a single experiment. By using an aperture to block electrons with large divergence angles and adjusting the solenoid’s focusing strength, we propose to converge the target-energy electron beam onto the aperture, increasing its transmission rate and optimizing the energy spread. Prior to optimization, the energy spread was approximately 3.57% at 536keV when using a 20µm diameter aperture.

Speaker: YuanYuan Qin (Tsinghua University)

14:00 Injection Background Studies at FCC-ee

The electron–positron Future Circular Collider (FCC-ee) is a proposed high-energy lepton collider designed to achieve unprecedented luminosity and precision in the study of fundamental particle physics. To fully exploit this potential, it is crucial to control beam-induced experimental backgrounds to ensure safe operation and optimal detector performance. This is particularly challenging due to the complex operational requirements; for example the top-up injection process that generates unavoidable losses at each injection while detectors are taking data. The present baseline scheme foresees a fast bump in the injection region that affects the full circulating beam, leading to beam-halo losses. In this paper, we study these losses, from their sources up to the detector using a multi-step simulation framework, employing multi-turn tracking followed by Monte-Carlo shower studies and detector occupancy analyses, to evaluate their potential impact on experimental detector performance.

Speaker: Giulia Nigrelli (European Organization for Nuclear Research, Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Sapienza University of Rome)

14:00 Inverse Modeling of Spatially Coherent Random Vibrations for Assessing Impact on Particle Beam Dynamics in Circular Accelerators

Vibrations cause emittance growth, beam misalignment at the interaction point, and particle loss, limiting accelerator performance. Ground motion and technical noise are characterized by absolute power spectral density (PSD) and spatial correlation. Mechanical support resonances, which amplify these effects, are determined via transfer functions. A method to generate random displacements from these vibration characterizations was developed using one- and two-dimensional inverse Fourier transforms. The generated displacements accurately reproduced the input PSD spectra and spatial correlation, as verified by Welch's estimation. As a demonstration, the displacements were applied to X-suite beam dynamics simulations of the FCC-ee booster lattice to assess emittance growth and beam offsets. The method enables iterative optimization of mechanical supports and beam transport systems to minimize vibration impacts.

Speaker: Purinut Lersnimitthum (Université Paris-Saclay)

14:00 Investigation and Diagnostic Potential of Off-Axis Resonance in THz Free-Electron Lasers

We study undulator radiation observed away from the beam axis for terahertz (THz) free-electron laser (FEL) beams. Earlier work on a single short bunch relates the continuous off-axis spectrum to the longitudinal bunch profile , without a discrete angular ‘resonance’ tied to micro-bunch harmonics. For a pre-bunched pulse-train beam, the bunching factor develops narrow spectral lines at the fundamental frequency and its integer harmonics. Off-axis phase matching selects a specific resonant polar angle for each line, producing pronounced, spatially separated ring-like intensity patterns in the coherent far field. We utilize the non-averaged 3D FEL code PUFFIN to simulate single-bunch radiation—reproducing non-integer harmonic patterns consistent with analytical Lié-nard-Wiechert (LW) results—and to demonstrate the expected off-axis resonance for pulse-train beams.

Speaker: Tong Li (Tsinghua University)

14:00 Investigation and Modeling of Intra-beam Scattering Effects in Micro-Bunched Beams

Intrabeam scattering (IBS) increases emittance and energy spread in low-emittance beams. In angular-dispersion-induced microbunching (ADM) beam lines, nanometre-scale density peaks cannot be represented reliably by a single smooth rms bunch length. This work separates the classical local IBS source from the microbunching spectrum: the former supplies the lattice and phase-space scattering kernel, whereas the latter modifies only the local pair-density weight. Rest-frame smoothing and a microbunching-dependent Coulomb-logarithm correction are introduced to exclude density structures below the collision resolution. For a 26 m branch line, the model gives single-pass microbunching-induced enhancements of 5.630% in the vertical-emittance source and 8.330% in the energy-spread-variance source. The additional source is concentrated in two intervals where the microbunching weight overlaps the local IBS kernel.

Speakers: Ao Liu (ShanghaiTech University), Ji Li (Shanghai Zhangjiang Laboratory)

14:00 Investigation of RF Surface Resistance in Sub-GHz Superconducting Elliptical Cavities Processed with Various Nitrogen-Doping Surface Treatments

Superconducting radio-frequency (SRF) cavity surface treatment with nitrogen-doping (N-doping) was a breakthrough in cavity processing which was found capable of increasing the cavity quality factor (Q0) by more than a factor of 2 compared to standard electropolish (EP) surface treatments, as well as achieving a highly desirable anti-Q slope behavior, an increase of Q0 with increasing accelerating field, in 1.3 GHz superconducting niobium cavities. N-doping has been extensively studied in 1.3 GHz cavities; however, a similarly significant increase in performance had not yet been observed in sub-GHz cavities. In this study, field-dependent BCS and residual resistances were measured in 644 MHz cavities for the FRIB energy upgrade with various surface treatments. The frequency dependence of the Q-slope was investigated by measuring BCS and residual resistances in the fundamental mode (FM) and 1.45 GHz higher-order mode (HOM) in the same cavity. We will report effects of various N-doping surface treatments on the FM and HOM performance, including achievements of Q0 as high as 4.9x10^10 at 17.5 MV/m in this class of SRF cavities.

Speaker: Sean Moskaitis (Facility for Rare Isotope Beams)

14:00 Investigation on the vacuum properties of Al-TiZrV bilayer films

Maintaining an ultra-high vacuum (UHV) environment is essential for the Hefei Advanced Light Facility (HALF) to achieve its design performance. Owing to the dimensional limitations imposed by small-aperture vacuum chambers, non-evaporable getter (NEG) films are commonly applied to the inner walls to enhance vacuum performance. However, conventional NEG films increase the resistive-wall impedance of the vacuum pipes, there-by exacerbating the wakefield effects. To address this problem, a novel composite film, Al-TiZrV, has been developed. By covering the TiZrV film surface with a highly conductive film, it can reduce the resistivity of the composite film. The results show that while the addition of the Al layer reduces the resistivity significantly, it increases the secondary electron yield (SEY), exacerbating the electron cloud effect. This study provides insights into the complex properties of similar bilayer films for future research on accelerator-related materials.

Speaker: Xinyu Jin (University of Science and Technology of China)

14:00 Investigations of a Novel Bunch Compression Technique for Hadron Accelerators

Bunch compression is necessary for many accelerator applications, one of which being the creation of muons for the proposed muon collider. The design of a proton driver to deliver a short and very intense proton pulse to a target for the creation of muons is being developed. Some challenges with the proposed baseline design, notably the ambitious requirements for the radiofrequency system, motivate the investigation of alternative compression methods. A series of chirped bunch trains can be compressed in the same compressor ring as in the baseline design, removing the need for an accumulator ring and radiofrequency cavities in the compressor ring. Such a scheme has been investigated using PyORBIT simulations, where the chirp is created by off-frequency cavities at the end of the linac. The impact of space charge was investigated, and was found to be too detrimental for realising the proposed scheme with the current parameters. However, other use cases are foreseen.

Speaker: Johan Holmberg (Lund University)

14:00 Investigations of Non-Linear Optics Control Knobs for the FCC-ee

The non-linear effects that arise from misalignment and field errors have been shown to degrade both the dynamic aperture (DA) and (MA) in simulation of the Future Circular Collider electron-positron machine (FCC-ee). This study focuses on using multipoles, such as octupoles, to control the amplitude detuning and higher-order chromaticity as well as investigation of dedicated non-linear correctors to control affected resonance driving terms (RDTs). These non-linear parameters are often coupled and the relative strength with which lattice elements act on each non-linearity depends on the local optical parameters. Studies were performed on the placement and strength of non-linear lattice elements to develop orthogonal correction knobs and first attempts at higher-order corrections to recover the reduced DA and MA are explored.

Speaker: Patrick Hunchak (University of Saskatchewan)

14:00 Laser phase noise measurements and analysis in High-power Optical Enhancement Cavity

Optical resonators serve as excellent spatiotemporal filters and are widely used for suppressing laser phase noise and stabilizing laser frequency. They can also function as passive optical enhancement cavities, providing power gains of thousands to tens of thousands. High-power optical enhancement cavities hold promise for applications such as steady-state microbunching (SSMB) advanced light sources and gravitational wave detection. However, systematic studies on the phase noise characteristics of high-power optical enhancement cavities remain lacking. In this paper, based on a high-power optical enhancement cavity platform, we measure the phase noise of both the injected laser and the transmitted laser, and investigate the influence of key cavity parameters on the phase noise performance, thereby providing valuable references for the application of high-power optical enhancement cavities.

Speaker: Zhou Yang (Tsinghua University)

14:00 Laser wakefield acceleration in carbon nanotube bundles

Laser wakefield acceleration (LWFA) can produce accelerating fields of several hundred GV/m, greatly reducing accelerator size and cost. Carbon nanotube (CNT) bundles, featuring high plasma density (>10$^{19}$ cm$^{-3}$), tunable effective density, excellent thermal properties, and empty channels that enable laser propagation, have attracted interest as solid-state plasma sources. Previous studies suggested that CNT-based structures can increase the acceleration field to the TV/m range, making them promising for compact radiation sources and radiotherapy. However, the insufficient beam quality still limits their broader application. In this work, we model a hollow solid-state plasma channel composed of CNT bundles. A 2 PW laser from the ELI-ALPS High-Field Laser facility is injected into the channel, where self-injected electrons at the nC-scale are trapped and accelerated in a TV/m field, as shown by particle-in-cell simulations with WarpX. Comparing with previous LWFA results using solid-state targets, we obtain an electron beam with > 2 nC charge and > 100 MeV mean energy, while achieving an unprecedented energy spread < 5%, by tuning the filling factor, bundle diameter, and gap size. We clarify that the large energy spread in the overdense plasma arises from the laser-plasma instability. In addition, we observe strong scattering within the overdense bundle walls. We further aim to investigate how the scattering affects the laser field and, consequently, the beam quality.

Speaker: Jiaqi Zhang (University of Manchester)

14:00 Laser Wire Scanning for 2D Electron Beam Size Measurement in Slant-Scattering Mode at SLEGS

The precise measurement of electron beam profiles is important for accelerator diagnostics. Laser wire scan is a classical and practicable method for beam size measurement which is based on Laser Compton scattering. Conventional laser wire scan methods require two separate scans: one for the horizontal and one for the vertical size. However, the slant-scattering geometry of Shanghai Laser Electron Gamma Source (SLEGS) beamline station enables the simultaneous projection of both dimensions onto a gamma-ray intensity profile, allowing both sizes to be extracted from a single scan. To enable this extraction, we developed a novel analysis approach. This approach involves numerical integral modeling of the slant-scattering process with a genetic algorithm to optimize the beam parameters. Using this method, we successfully measured the transverse electron beam size at the interaction point in the slant-scattering mode of SLEGS.

Speaker: ZhenWei Wang (Shanghai Institute of Applied Physics, Chinese Academy of Sciences)

14:00 Laser-plasma accelerator based EUV-FEL plasma source development at ELI-ERIC

Laser-plasma accelerators (LPAs) can generate high-energy, high-quality electron beams, paving the way for a new generation of compact free-electron lasers (FELs).
To achieve this, beam stability and repeatability must improve, relying on advances in high-power lasers and plasma-source development. These are key technologies for the 100 Hz LPA-based FEL, under development at ELI ERIC for EuPRAXIA.

In this report, we analyse two plasma-target concepts designed to generate stable, high-quality electron beams essential for compact Extreme Ultraviolet (EUV) FEL applications.
The initial technique creates plasma channels through electrical discharge within a capillary. These channels enhance LPA stability by guiding the laser pulse, and maintaining the laser's focus, thereby improving energy transfer. The characteristics of the channel are influenced by the capillary's shape, gas conditions, and discharge setup.
The second approach uses discharge-free capillaries functioning as gas cells. By modifying the capillary geometry, the plasma density profile can be adjusted to facilitate self-truncated ionisation injection and localise the electron injection. Independent gas inlets allow separate optimisation of injection and acceleration regions.
Furthermore, we investigate the laser-plasma interaction and electron beam acceleration for two different plasma targets using Particle-In-Cell modelling and assess whether the resulting electron beam quality is suitable for LPA-based EUV FEL.

Speaker: Alex Whitehead (Extreme Light Infrastructure Beamlines, Czech Technical University in Prague)

14:00 Laser-Plasma Electron Injector for the cSTART Storage Ring

Laser-plasma accelerators (LPAs) generate ultrashort, high-intensity electron bunches in a compact form factor. At Karlsruhe Institute of Technology (KIT), we are developing an LPA for direct injection into a specifically built storage ring with high momentum acceptance. The cSTART storage ring (compact storage ring for accelerator research and technology) can be tuned to energies between 50 – 90 MeV, and its lattice is designed to accept electron beams with +/- 4% energy spread. Furthermore, the ring lattice can be set up for the storage of ultrashort electron bunches. The LPA electron injector must be readily tunable to match the storage ring parameters. This contribution reports proof-of-concept experiments that demonstrate the generation of high-quality LPA electron beams with parameters that fulfill the cSTART requirements.

Speaker: Alexander Saw (Karlsruhe Institute of Technology)

14:00 Lattice design to achieve reversible microbunching in a steady-state microbunching (SSMB) storage ring

Steady-state microbunching (SSMB) has been proposed as a new light source mechanism to generate high average power coherent radiation in electron storage rings. One approach to achieving SSMB is the reversible microbunching scheme, which introduces a laser-based energy modulation to electron bunches in a localized insertion section to form microbunching, and then uses a subsequent energy demodulation to remove the microbunching and restore the bunches to their nominal state in the storage ring. In this paper, we report a modulation–demodulation lattice design for an SSMB storage ring based on the reversible microbunching approach. By self-consistently accounting for non-ideal effects such as intrabeam scattering (IBS) and higher-order nonlinearities, sub-nanometer longitudinal position deviations of the electrons between the laser modulators can be achieved, ensuring precise cancellation of the energy modulation and maintaining the electron bunches in a steady state, thereby ensuring high average radiation power.

Speaker: Jingyuan Zhao (Tsinghua University)

14:00 LEnuSTORM: A Low-Energy Muon Storage Ring for Neutrino Cross-Section Measurements

The LEnuSTORM (low-energy neutrinos from stored muons) is a proposed facility that enhances the performance of the ESSnuSB* (European Spallation Source Neutrino Super Beam) project by measuring neutrino cross sections in the energy range 200-600\,MeV, where data is largely missing. The facility utilizes a 1.25\,MW proton beam from the European Spallation Source linac, which is compressed in an accumulator into 1.2\,µs pulses and directed at a granular titanium target embedded in a horn. Pions collected by the horn are transferred and injected into a racetrack-shaped storage ring where they decay and emit muons that will be stored in the ring for a few tens of turns. The neutrinos emitted in the muon decay in one of the straight sections will travel to a water Cherenkov detector, where the interactions are monitored.

At LEnuSTORM, the beam is large and very divergent, and thus difficult to contain. The ring design presented in this paper uses iron-dominated magnets to reduce complexity, and a compact FODO lattice with strong focusing to maximize neutrino production by allowing a large transverse acceptance. However, the design pushes fringe-field effects beyond the linear regime and requires a paraxial expansion with higher-order terms, introducing resonances and reduced dynamic aperture. We present here a design that aims at balancing the transverse and momentum acceptance with the dynamic aperture, to maximise neutrino production.

Speaker: Ting Wing CHOI (Uppsala University)

14:00 Limiting Magnetic Field Measurements for SRF Cavities

Exploration of new recipes and novel materials for superconducting RF cavities is necessary to push to higher quality factors and accelerating gradients. The superheating field is the material property that sets the limit on the maximum accelerating gradient achievable for a superconducting cavity of a given geometry. The Cornell SuperHeating Radiofrequency Pulsed Power Probe (C-SHRP^3) is a sample host cavity designed to measure the superheating field of material samples. We present results on superconducting materials of interest to the SRF community that demonstrate the high-field potential of novel materials.

Speaker: Nicole Verboncoeur (Cornell University (CLASSE))

14:00 Linear and Nonlinear Effects of Fringe Fields on the Single-Particle Dynamics in the Helium Light Ion Compact Synchrotron

HeLICS (Helium Light-Ion Compact Synchrotron) is a proposed cancer treatment facility developed within the Next Ion Medical Machine Study (NIMMS) at CERN, designed both for clinical treatment with protons and research with helium ions. Consisting of a triangular lattice with six 60 degree combined-function magnets with 30 degree edge angles, this machine challenges the current treatment of fringe fields in beam dynamics simulations. At present, accurate maps for the fringe fields of curved combined-function magnets with edge angles are not available in the literature. This work investigates the linear and non-linear effects of these fringe fields through the framework of resonance driving terms, providing an alternative approach to quantify their influence on single-particle dynamics.

Speaker: Silke Van der Schueren (European Organization for Nuclear Research)

14:00 Localized Response Basis for Data-Efficient Transverse Beam Distribution Reconstruction Using a Multimode Fiber Relay

Transverse beam imaging in radiation areas can be supported by relaying scintillation light through a multimode fiber (MMF) to a camera placed in a shielded area. However, the MMF scrambles the input, so a trained model is required to recover the beam distribution. This work studies a data efficient calibration method in which measured input and MMF output basis pairs are used as building blocks to synthesize training data for the reconstruction model. After an initial digital micromirror device based validation, the method was assessed using real beam data from CERN CLEAR, where data synthesized from a raster scan basis were used to train a convolutional autoencoder. The best model using this strategy achieved 7.37% mean normalized root mean square error (RMSE) across four transverse beam parameters, compared with 6.02% for a random scan reference model using roughly twice as many fully paired random scan samples. These results suggest that basis-based synthesis training, when combined with suitable beam image priors, can reduce reliance on large random scan MMF calibration datasets by replacing part of the calibration with a controlled scan of fixed size.

Speaker: Mr Qiyuan Xu (Cockcroft Institute)

14:00 Longitudinal Beam Dynamics Investigations at the GSI UNILAC for non-relativistic ion beams

At the heavy-ion accelerator UNIversal Linear ACcelerator (UNILAC) at GSI Helmholtz Center for Heavy Ion Research (GSI) in Darmstadt, measurements of the longitudinal emittance were performed using a Fast Faraday Cup (FFC) installed in a dispersive section. The FFC provides high-resolution, time-resolved measurements of the charge distribution along the longitudinal beam profile. Different buncher settings were applied to study the longitudinal beam dynamics and identify the phase and energy foci at the FFC location. Based on these measurements, beam dynamics calculations were carried out to determine the longitudinal emittance at the exit of the Alvarez section. Measurement and calculation results will be presented.

Speaker: Nimue Schmidt (GSI Helmholtz Centre for Heavy Ion Research, Technical University of Darmstadt)

14:00 Longitudinal Beam Instability in SSMB Laser Modulators: A Cavity Mode Decomposition Approach

Steady-state microbunching (SSMB) is a promising mechanism for generating high-average-power coherent radiation by maintaining microbunches in a storage ring. In an SSMB laser modulator (LM), the interaction between electron bunches and the recirculating coherent undulator radiation can drive longitudinal beam instabilities, which may limit the overall performance. In this work, we investigate the longitudinal single-bunch multi-turn instability using a cavity mode decomposition approach. The evolution of the longitudinal wakefield is derived by expanding the radiation into a complete set of cavity eigenmodes, accurately capturing the optical evolution of the field over multiple turns. The longitudinal beam dynamics equations are formulated to analyze the instability growth rates. Numerical simulations show excellent agreement with the theoretical model, validating the mode decomposition technique. These findings provide critical insights into the instability characteristics and suggest effective mitigation strategies for the design and operation of SSMB storage rings.

Speaker: Yingjie Dai (Tsinghua University)

14:00 Longitudinal Matching and Timing Control Studies for the PERLE Energy Recovery Linac

In an Energy Recovery Linac (ERL), precise longitudinal dynamics control is essential for both delivering the required bunch parameters at the interaction points and for enabling energy recovery. This paper will specifically talk about these studies for the PERLE accelerator. PERLE (Powerful Energy Recovery Linac for Experiments) is a proposed high-power ERL delivering a 250 MeV, 20 mA beam (5 MW). Its multi-pass lattice combines the energy of circular machines with the beam quality of a linac, but also inherits their main limitations. In particular, this paper will present studies done of longitudinal matching, this means setting the right correlation between the particle’s longitudinal position and its energy, as well as developing a chicane for timing control.

Speaker: Janine Issa (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

14:00 Loss reduction methods through longitudinal laser scraping techniques after a Radio-Frequency Quadrupole

Investigation into laser-based manipulations on the longitudinal phase-space of bunches has been conducted experimentally at Fermilab’s linear accelerator. We continue to explore the advantages of using such a system in the application of beam-loss reduction. Particle bunches exiting the RFQ have been bunched to roughly 201 MHz or 4 ns FWHM. These particles then enter a small drift prior to the first acceleration module. During this drift, simulation shows that it is feasible to reduce the number of large change-of-energy particles via longitudinal scrapes, thus leading to a theoretical reduction in losses further downstream. Utilizing experimental data, we model laser and H⁻ interactions replicating those found within the Laser Notcher interaction cavity and further effects down the linac. We propose a method using Laser-Notcher-like systems as a solution to mitigate losses in future accelerating systems.

Speaker: Parker Landon (Boston University, Fermi National Accelerator Laboratory)

14:00 Low-Power Test of Bridge Coupler Connected to Tank in Disk-and-Washer Structure for Muon Acceleration

A muon linear accelerator is under development at J-PARC for precise measurement of the muon anomalous magnetic moment (g-2) and search for the electric dipole moment (EDM). The disk-and-washer (DAW) structure is employed to accelerate muons from 30% of the speed of light (kinetic energy = 4 MeV) to 70% (40 MeV) at 1296 MHz. The muon DAW consists of tanks accelerating the muons and bridge couplers that couple the tanks and focus the beam using an internal quadrupole doublet. A bridge coupler prototype was fabricated and tested at low power. This Low-power test focused on measuring resonant frequencies, Q-value, and electric field distribution. Furthermore, the bridge coupler prototype was connected to a tank prototype and tested at low power to understand the effects of the connection. This paper summarizes these results and discusses the prospects for actual machine production.

Speaker: Ayaka Kondo (Nagoya University)

14:00 Machine Learning based preventive maintenance and autonomous power control for RF cavities in a free-electron laser

This project develops a machine learning–based system to prevent RF cavity trips in the free-electron laser by autonomously controlling the applied RF power. Sudden vacuum and current fluctuations within the cavities can cause reflections that trip the machine, and continuous manual monitoring throughout the conditioning process isn't feasible. To address this and potentially improve the conditioning efficiency, process-variable data was collected and analyzed to identify patterns in cavity behavior across operating power levels. A hybrid model combining clustering methods, linear regression, and a classifiers was designed to categorize current ranges, estimate baseline behavior, and detect anomalies. The resulting control program evaluates the machine state over short intervals, decreases power during unsafe conditions, increases it during prolonged stability, and can automatically reset the RF system after a trip. This approach enables faster and safer conditioning of the RF cavities, reduces operator workload, and provides a pathway toward fully autonomous preventive maintenance.

Speaker: Mr Ashish Sharma (Indian Institute of Technology Delhi)

14:00 Machine learning techniques for design of complex accelerator magnets

The design of multipole and other magnets for accelerators is typically an iterative process in which the magnet geometry is optimised for the required beam dynamics properties. Modelling the field for a given geometry can be computationally expensive, so exploring the parameter space can be a time-consuming procedure. The task is particularly challenging when complex field properties are needed (for example, in magnets with several multipole components or with longitudinal field variation). Combined function magnets with several multipole components are particularly useful in accelerators with tight spatial constraints such as an X-ray Free Electron Laser (XFEL). Surrogate models using neural networks can provide a way of rapidly generating possible magnet geometries for given field or beam dynamics requirements. In this contribution, we discuss how machine learning tools may be used to improve the efficiency of the design process for complex accelerator magnets, and present results from a case study based on a combined function magnet for the beam spreader in a future XFEL.

Speaker: Sophie Gresty (University of Liverpool, Cockcroft Institute)

14:00 MAGNETIC CENTER MEASUREMENT AND FIDUCIALIZATION METHOD FOR HALF

To meet the stringent alignment requirements for accelerator magnets in the Hefei Advanced Light Facility (HALF),
accurate fiducialization of the magnetic center is essential.
This paper presents a high-precision and efficient fiducialization method developed for HALF, based on a single stretched
wire bench integrated with a precision surface plate. The
system enables precise determination of the relative coordinates between the magnetic center and the magnet fiducials.
Experimental results demonstrate that the overall fiducialization accuracy is better than 10 µm, thereby satisfying the
rigorous demands of magnetic center fiducialization for the
HALF project.

Speaker: BaoHou Liu (University of Science and Technology of China)

14:00 Magnetic field reconstruction from sparse measurements for complex geometries

Precise 3D field measurements of large, complex magnet geometries are time-consuming and error-susceptible. For large magnets, it is common to record Hall probe data on a sparse grid, then use an interpolation algorithm to estimate field values at the remaining points. For common magnet geometries, such as quadrupoles and dipoles, linear interpolation often provides accurate results. However, for complex magnet geometries, this method can yield lower accuracy. In this paper, we present a method based on a locally Maxwell-consistent algorithm for sparse Hall probe measurements. Through the k-nearest neighbors algorithm, we locally fit the magnetic field with Tikhonov regularization. We test this method on a novel Compton spectrometer, capable of measuring single-shot, double-differential, energy-angle gamma spectra, ranging from 180 keV to 28 MeV. Using held-out validation, we demonstrate that we can reconstruct its magnetic fields with higher accuracy than linear interpolation and radial basis function (RBF) interpolation with cubic, thin plate spline, and quintic kernels. We also analyze the dependence of point sparsity on accuracy.

Speaker: Jack Phillips (Particle Beam Physics Lab (PBPL), University of California, Los Angeles)

14:00 Mapping Global Collaboration in Accelerator Research

This contribution analyses particle accelerator research through a sociological lens by examining publication collaborations across regions and scientific fields. It combines a database of accelerator counts per country with a large corpus of accelerator-related publications from Web of Science. Rather than focusing on technical differences between machines, the study examines how publication networks structure relationships between regions and research fields. The results show marked regional contrasts, with some countries sustaining dense internal publication networks while others depend more on cross-regional partnerships. The analysis also identifies strong links between the presence of accelerators in a region and the intensity of its collaborative activity, as well as clear disciplinary differences in how fields such as astronomy, materials science, and chemistry mobilise accelerator-related research. Taken together, these patterns illustrate how scientific collaborations crystallise around infrastructures, how expertise circulates between regions, and how accelerators support the emergence of interconnected epistemic communities. The study offers an empirical perspective on the social dynamics underpinning global accelerator research.

Speaker: Annabella Zamora (University of Lausanne)

14:00 Measured and simulated channeled-halo distributions for the TWOCRYST experiment at the LHC

The TWOCRYST experiment at the CERN Large Hadron Collider provides a unique setup to study the behaviour of high-energy beam particles channelled by bent crystals. Two two-dimensional detectors in Roman Pots enable direct observation of channelled protons at energies from 0.45 TeV to 6.8 TeV. We present measured channelled-beam distributions for two bent silicon crystals with 50 urad and 7000 urad bending and compare them to combined beam-dynamics and particle–crystal interaction simulations including the full LHC lattice. The measured positions of the channelled beam is compared with beam-position-monitor data of the main beam to assess the sensitivity of the channelled-beam trajectory to realistic orbit drifts, providing key input for the requirements of future bent-crystal-based fixed-target experiments.

Speaker: Chiara Maccani (University of Padua, European Organization for Nuclear Research)

14:00 Measured properties of the mixed helium and carbon ion beam at MedAustron

The implementation of a sequential injection scheme for mixing helium and carbon ions from different ion sources at the MedAustron accelerator facility enabled the first successful delivery of a mixed helium and carbon ion beam in a synchrotron therapy facility. A precise knowledge of both the helium and the carbon properties is an essential input for designing treatment monitoring experiments, however, it is not trivial to distinguish the helium and carbon beam properties within the mixed beam.

Within this contribution, we discuss methods to characterize the properties of the extracted mixed 4He2+ and 12C6+ beam in the experimental room and present respective measurements from the beam that is currently delivered to treatment monitoring research experiments at MedAustron. A key property is the ion composition, where the helium content can be varied between 0-100% using the sequential injection scheme. While this possibility of tuning the mixing ratio is highly beneficial to the experiments, the achieved mixing ratio (usually between 10-20% required) is currently subject to significant shot-to-shot fluctuations. Moreover, we discuss observed differences in the transverse beam sizes of the extracted helium and carbon ion beams.

Speaker: Mr Matthias Kausel (MedAustron)

14:00 Measurement of dielectric properties of 3D printed polymer-based materials for RF applications at 500 MHz

To include 3D printed polymer-based materials in accelerator parts the relative permittivity and the dielectric loss tangent of these materials have to be well known. A quarter wave cavity was built to measure these properties at a resonance frequency of 500 MHz by inserting a cylinder of the material under test, resulting in a frequency and quality factor shift of the cavity. By fitting the measured data to detailed CST simulations, the values of the relative permittivity and the dielectric loss tangent can be obtained. These results provide the necessary material parameters for further investigations into their use in RF accelerator components such as power couplers.

Speaker: Philipp Müller (Goethe University Frankfurt)

14:00 Measurement of local chromaticity in the LHC

Local chromaticity can be defined as the local variation of the total betatron phase advance with momentum deviation $\delta$, and it can be interpreted as a measurement of the chromaticity generated over a limited segment of the lattice, rather than for the entire ring. It can be a useful tool to understand various insights of the beam operation, in particular how the phase is locally modulated by $\delta$ and how the overall chromaticity builds up along the lattice. The local chromaticity was first evaluated in the Large Hadron Collider (LHC) during the Run 3 commissioning in 2025, when a large RF frequency scan was performed up to $\pm \, $350 Hz, revealing a very large discrepancy with respect to the LHC optics model. This paper presents the methods and the results of the analysis.

Speaker: Mattia Stefanelli (European Organization for Nuclear Research, National Institute for Subatomic Physics)

14:00 Measurement of the saturation length of the self-modulation instability in a plasma wakefield accelerator

Plasma wakefield accelerators can sustain very high accelerating gradients (1-100GeV/m), but energy gain is often limited by energy depletion of the drive bunch. The AWAKE experiment addresses this limitation by using a 400GeV proton bunch from the SPS. The bunch is much longer than the plasma wavelength and must first transform into a train of microbunches to excite large-amplitude wakefields. This train forms through the transverse self-modulation (SM) instability. High-gradient acceleration of a witness bunch can only occur once the train is fully formed, i.e., after saturation of SM, and thus measuring the saturation length ($L_{sat}$) of SM is crucial for the design of an accelerator with this scheme.
We present the first determination of $L_{sat}$ using experimental and numerical simulation results. By measuring the transverse distribution of the bunch after the plasma as a function of plasma length, we determine $L_{sat}$ and find that it decreases when increasing the plasma density, and that seeding SM makes $L_{sat}$ shorter. For all parameters relevant to AWAKE, saturation of SM occurs well within the 10m foreseen for the length of the self-modulator in future acceleration experiments.

Speaker: Arthur Clairembaud (Max Planck Institute for Physics)

14:00 Mechanical design and structural analysis of septum magnet for Thailand new synchrotron light source (SPS-II)

The Synchrotron Light Research Institute of Thailand is developing a new eddy-current septum magnet as part of the pulsed magnet systems for its next-generation synchrotron light source, the Siam Photon Source II (SPS-II). This work focuses on mechanical design and structural analysis of the septum magnet to improve the prediction of anomalies and potential failures over the machine's operational lifetime. Finite element method is used to evaluate both static deformation of the in-air magnet yoke and transient vibration response of the septum blade under pulsed magnetic force, which can induce fatigue damage through cumulative stress cycles. Static analysis indicates that the proposed design satisfies structural integrity and magnetic field uniformity requirements. The impulse vibration fatigue assessment of the septum blade falls within the ultra-high-cycle fatigue (UHCF) regime, with stablished S-N data for copper alloys providing design guidance for extending the magnet's operational life.

Speaker: Kantanat Phochanasombut (Chulalongkorn University)

14:00 Mid-T-Baking of SRF Cavities Driven by RF Power

Mid-T (ca. 220 to 350°C) heat treatment is known to improve the dissipation of superconducting Nb cavities by dissolving the surface oxide and diffusing oxygen into the near-surface bulk. HZB explores the use of RF power coupled into the cavity as a technique to perform the heat treatment directly in the cryostat, thereby also avoiding venting and re-oxidation following the treatment. Such an RF-driven heating may be an attractive option for in-situ processing of an operation-ready accelerator module. We have demonstrated effective RF heating both with a TESLA-9-cell and a 1.5 GHz single-cell cavity reaching temperatures of 207°C (TESLA cavity) and 260°C (VSR single cell). Whilst the TESLA-cavity was driven via the fundamental power coupler using various modes of the fundamental passband, the single cell was heated using a higher-order mode at 4.263 GHz. The later was selected because of both its strong coupling and acceptable homogeneity of RF power dissipation. Experiments took place in two cryostats, HZB’s HoBiCaT and the Large Vertical Test Stand (LVTS), operated under elevated temperatures. In this paper, details of the experimental setup and process, heating performance and, in case of the single cell, a subsequent cold test are reported.

Speaker: René Schöder (Helmholtz-Zentrum Berlin für Materialien und Energie)

14:00 Minimizing Slice Energy Spread Photocathode RF Gun for Ultrashort Electron Bunch Generation

Slice energy spread is a key beam-quality parameter that limits the compression of ultrashort electron bunches. To suppress the RF-dominated slice-energy-spread growth in a photocathode RF gun, a 2.3--2.3 cell configuration with a cascaded cavity with a decelerating field is proposed on the basis of the quasi-DC 2.3-cell X-band gun. Simulations show that, without space-charge effects, the slice energy spread can be reduced from 121~eV to 37~eV, and further to 5~eV after field-ratio optimization. The proposed scheme also exhibits good tolerance to variations in the initial beam parameters, although its compensation capability at high bunch charge is limited by nonlinear space-charge effects. These results demonstrate that the cavity with a decelerating field provides an effective approach for the development of low-slice-energy-spread RF guns for ultrashort bunch generation.

Speaker: Ms Fengyi Zhang (University of Science and Technology of China)

14:00 Modeling and Measuring the Effect of Mismatched Beam Transport on Halo Formation in a High-Intensity LINAC

Ongoing studies at the Spallation Neutron Source (SNS) Beam Test Facility (BTF) seek to characterize halo formation in the early stages of a high-power linac with specific focus on determining the contribution from mismatched beam transport and to replicate halo measurements using well-benchmarked particle-in-cell simulations. The BTF is a 2.5 MeV, 10- meter test beamline equipped with advanced phase space diagnostics allowing detailed characterization of beam distributions. This talk details recent advances in improved transport of mismatched cases in the BTF, direct measurements of 2D phase space projections with 6 orders of magnitude in dynamic range, and comparisons of predictions from the PyORBIT code to measured distributions.

Speaker: Trent Thompson (Oak Ridge National Laboratory)

14:00 Modeling of CSR and its cancellation in DBA/Chicane type compressors

In advanced accelerator-based light sources and colliders, bunch compressors like arc-type (DBA) and linear-type (chicane) are widely used to generate high-quality electron beams with kiloampere (kA)-level peak currents. However, a serious problem in increasing the peak current even higher is the significant degradation of beam quality caused by the Coherent Synchrotron Radiation (CSR) effect. To tackle this, we develop a new analytical model for CSR that can describe beam transport with varying bunch lengths, establish a practical framework for analyzing CSR in both DBA and chicane-type compressors, and design CSR-suppressed DBA compressors (arc-type) as well as non-symmetric C- and S-shaped chicanes (linear-type). General analytical conditions for CSR cancellation are derived for these designs. Simulations show that, with these new compressors, high beam quality can be maintained even when the peak current is increased up to 10 kA. This work provides important guidance for enhancing the performance of existing accelerator facilities, as well as for the development of next-generation accelerator-based light sources and colliders.

Speaker: Fancong Zeng (Chinese Academy of Sciences)

14:00 Modeling of Multiturn Injection at SIS-18 for a Train of UNILAC Microbunches

Multiturn Injection is an essential tool for achieving high beam intensities in synchrotrons. At SIS-18, a significant increase in the intensity of the uranium beam is foreseen, by several orders of magnitude up to 1.5x10e15 ions per injection cycle, prior to acceleration and extraction to SIS-100. Under these conditions, any beam losses during injection become critical, both in terms of beam lifetime and the risk of damaging injection system components, in particular the electrostatic septum.
Usually, the optimization of the multiturn injection is carried out by considering only the process of injecting one transverse slice of macroparticles from UNILAC per turn. We present here a three-dimensional modeling of the injection process, which takes into account the longitudinal structure of the injected beam, namely the train of microbunches, and evaluates differences from previous approaches.

Speaker: Annemarie Lauterbach (Goethe University Frankfurt)

14:00 Modeling of Radiation Wakefields using a Scattered Field Formulation

Simulations of particle beam dynamics in electron accelerators need to account for both internal space charge effects and transient electromagnetic waves scattered at chamber walls. Commonly, these effects are treated separately using very different simulation techniques. We have developed a coupling procedure to account for both effects simultaneously by using a scattered field formulation. Here, we combine two field solvers optimized to simulate either the internal beam dynamics assuming free space or the transient electromagnetic wave propagation.

Previously, the coupling procedure was restricted to quasi-static beam behavior, as is sufficient for linear movement and emission from the gun. In this contribution we extend the approach to account for scattered synchrotron radiation wakefields from bent trajectories. We present computational studies of the scattered CSR effect created in bunch compressors, specifically the BC0 of the European XFEL. No restrictions are imposed methodologically on the surrounding geometry or on the flight path of the beam. Hence, our approach is much more general than CSR models used in the past, which assumed for example pre-defined trajectories in between two parallel plates and rigid bunches. At the same time, due to the de-coupled solvers, our method allows to compute particle-particle CSR fields inside the bunch using free-space assumptions, which reduces modeling complexity significantly.

Speaker: Jonas Christ (Technical University of Darmstadt)

14:00 Modelling and anomaly detection for Diamond-II Beam Loss Monitors using machine learning techniques

The losses measured by Beam Loss Monitors (BLMs) at synchrotron light source facilities offer useful but indirect insight into the state of the beam. Frequent changes to insertion devices, beam current, temperature, humidity, and other factors make the line between normal operation and anomalous behaviour unclear. Data was collected passively during user beam on the storage ring of Diamond Light Source over several months, as well as actively during dedicated machine shifts. A variety of machine learning techniques were employed to model the behaviour in this data, enabling anomaly detection and aiding machine operations.

Speaker: Mr Corey Lehmann (University of Oxford)

14:00 Modelling Dust Grain Ionisation and Dynamics in Flat Lepton Beams Using a Sliced Approach

Interactions of dust grains with the particle beams can degrade the performance of modern high-intensity accelerators. Existing models developed for the LHC assume grains smaller than the beam size and therefore a spatially uniform primary-particle flux through the grain. This approximation breaks down in flat lepton beams, where the vertical beam size can be smaller than the dust grain.

To describe this regime, a model is introduced for the ionisation and dynamics of dust grains interacting with electron, positron, and proton beams. The grain is discretised into slices, allowing position-dependent ionisation to be treated spatially. The equation of motion is solved with a time-dependent charge using an ionisation model adapted to flat-beam geometries. Application to representative FCC-ee and SuperKEKB parameters provides first quantitative estimates of the penetration depth of charged dust grains.

Speaker: Philipp Ziegler (European Organization for Nuclear Research, Goethe University Frankfurt)

14:00 Modelling Linear Coupling for FCC-ee in Xsuite

Accurate control of the transverse linear coupling is important for achieving the target luminosity in FCC-ee. We have implemented a simplified FCC-ee coupling model in Xsuite based on linear maps and on local lattice coupling matrices. This approach is benchmarked against the full FCC-ee optics model, showing good agreement in the behavior of betatron tunes, beta functions, and coupling-related quantities. The underlying coupling matrix transformations are derived, as a function of some coupling parameters, and checked for consistency by benchmarking against analytical calculations of resonance driving terms (RDT)s. The coupled FCC-ee models are then used to study changes to IP beam size and luminosity caused by controlled excitation of skew-quadrupole pairs in the interaction regions. The results from the full lattice are compared with those obtained by linearised maps. This work presents a practical framework for coupling studies and provides a basis for developing FCC-ee coupling correction and luminosity tuning procedures.

Speaker: Vaibhavi Gawas (European Organization for Nuclear Research)

14:00 Modelling of counter-rotating multi-turn wakefields in the muon collider RCS chain

The future multi-TeV muon collider facility will employ a superconducting radiofrequency (RF) system with thousands of cavities in the rapid-cycling synchrotron (RCS) chain. This RF system, common to both beams, will accelerate two counter-rotating $\mu^+$ and $\mu^-$ bunches simultaneously. Due to the high intensity of up to $2.7 \times 10^{12}$ particles per bunch, the induced voltage in both the fundamental and several higher-order modes is significant. A strong impact on longitudinal beam quality and the luminosity in the collider is expected. Modelling wake potentials in the RF system of the RCS chain is challenging. The long-range wakefields will interact with both the co- and counter-rotating bunches due to the high quality factor and corresponding long decay constants of the fields in the cavities. These two-beam interactions are studied, with particular attention to the specificities caused by the directionality of the induced fields.

Speaker: Mr Leonard Thiele (University of Rostock)

14:00 Monochromation of pulsed electron beams with terahertz radiation

Controlling the energy profile of an electron beam is important for continuous and time resolved spectroscopic and imaging applications that require narrow energy spreads. The energy spread of an electron beam is fundamentally limited by the source, but energy spread that is correlated in time or space can be corrected using an appropriate time- and space-varying force. We present a method of reducing energy spread in photo-emitted electron beams in which laser-derived terahertz fields are used to shape the radial and temporal phase spaces. We show analytically and in particle tracking simulations the absolute limits of monochromation that this technique can achieve for a given source, and characterize non-ideal effects that occur at higher frequencies. The interaction is facilitated by a mirror which is reflective to terahertz and largely transmissive to the electron beam, requiring current losses of only a few tens of percent. Our method significantly outperforms the current output of prism-based monochromators while achieving comparable monochromation.

Speaker: Cecilia Abbamonte (Cornell University (CLASSE))

14:00 Monochromatization Optics for FCC-ee Optimized Performance Study and First Attempt for IR Optics Design for FCC-ee LCC Lattice

Monochromatization is one of the most intriguing proposed operation modes of the FCC-ee, enabling a significant reduction of the centre-of-mass (CM) energy spread to a level comparable to the Higgs boson’s natural width produced through the s-mode direct channel at 125 GeV.
Previous studies demonstrated its feasibility using earlier versions of the FCC-ee Global Hybrid Correction (GHC) optics. A first draft implementation of the scheme on the Local Chromaticity Correction (LCC) lattice is explored in this paper. The performances of the new optics types are presented in terms of luminosity and energy spread, supported by the simulation results. This provides an early outlook on the potential operational flexibility of future FCC-ee configurations operating in monochromatization mode.

Speaker: Anna Korsun (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

14:00 Morphological Evolution and Electrical Transport Studies in Ultrathin Te Films under 80 MeV Ag⁷⁺ Ion Irradiation

Ion beam irradiation is a powerful technique for defect engineering, offering precise control over ion fluence and energy. In this study, tellurium thin films deposited by thermal vapor evaporation were irradiated with 80 MeV Ag⁷⁺ ions at fluences ranging from 1×10¹¹ to 3×10¹² ions/cm². XRD shows a reduction in crystallite size and increasing tensile strain with fluence, supported by Williamson–Hall analysis.Raman spectra exhibit redshifts and broadening of the A1 and E2g modes, confirming defect formation and lattice disorder. AFM reveals fluence-dependent changes in grain morphology and surface roughness, while RBS verifies Te stoichiometry with only minor sputtering. UV–visible spectroscopy indicates enhanced optical absorption after irradiation. Hall measurements confirm n-type behavior with carrier concentration increasing from 2.12×10¹⁶ to 1.74×10¹⁷ cm⁻³. Temperature-dependent resistivity shows a reduced activation energy, and I–V curves under dark and 10 mW illumination reveal substantial photocurrent enhancement. Overall, SHI irradiation effectively tailors defect states, transport properties, and photo response in tellurium thin films for next-generation optoelectronic applications.

Speaker: Ms UPASANA BORDOLOI (Indian Institute of Technology Delhi)

14:00 Multi-Objective Bayesian Optimisation (MOBO) for High-Quality Photoinjector Optimisation

Optimising SRF photoinjectors is a challenging task due to the high-dimensional, nonlinearly coupled parameters and competing objectives such as transverse emittance and bunch length. Conventional methods such as manual tuning or MOGA require thousands of evaluations and are impractical for routine operation or computationally expensive simulations. This work presents a multi-objective Bayesian optimisation (MOBO) approach that uses Gaussian-process surrogate models and tunable, uncertainty-aware acquisition functions to identify Pareto-optimal solutions in an order of magnitude fewer evaluations. When applied to the 1.4-cell SRF photoinjector at SEALab, and the 1.6-cell SRF gun and 20m injector beamline for EuXFEL, this optimisation outperforms MOGA in solution-efficiency and provides interpretable sensitivity information for injector tuning. These results demonstrate the potential of MOBO as an efficient, machine-ready strategy for SRF photoinjector optimisation.

Speaker: Emily Jayne Brookes (Helmholtz-Zentrum Berlin für Materialien und Energie)

14:00 Multi-Objective Bayesian Optimization of Multi-Stage OK-SASE for Efficient High-Energy XFEL Operation

Femtosecond hard X-ray radiation beyond 12.4 keV enables unprecedented opportunities for probing matter at atomic scales, however, its generation remains challenging for self-amplified spontaneous emission (SASE)-based XFELs due to reduced FEL gain, leading to extended undulator requirements and limited radiation efficiency. To address this issue, we investigate a multi-stage optical-klystron SASE (OK-SASE) scheme that enhances microbunching through dispersive sections and shortens the gain length. A multi-objective Bayesian optimization (MOBO) framework is introduced to systematically optimize the configuration. Using SHINE as a representative case, steady-state simulations at 15 keV show that the optimized setup reduces the required undulator length relative to conventional SASE by about 7% to 22%, depending on the electron-beam energy spread. The optimization indicates that several chicanes can remain effectively inactive, enabling a more compact beamline layout. Time-dependent simulations also demonstrate the feasibility of multi-stage OK-SASE for efficient high-energy XFEL operation.

Speaker: Xiaodan Liu (Hunan University)

14:00 Multiparticle beam dynamics of ELEBT integrated with upgraded RFQ in LINAC4

Electrostatic low-energy beam transport (ELEBT) section as a part of future upgradation proposal in LINAC4 at CERN, is proposed to handle 45 keV H- ion beam with 70 mA max beam current. The design allows maximum input rms normalized emittance of 0.5 π mm mrad without significant growth. A dual einzel system is incorporated in the decelerating-accelerating (DA) mode to control beam blow up within 70\% of the beam pipe aperture. The ground electrode of these einzel systems also houses radio frequency electrodes for beam chopping. It chops the beam as per the requirement of the upgraded radio frequency quadrupole* (RFQ). The transverse and longitudinal beam optics are studied for the full system of ELEBT + RFQ. It is also validated theoretically using multi particle beam analysis. We achieved beam transmission more than 90\% with all emittances well in control. The design details with respect to field computation and beam dynamics will be presented.

Speaker: Niketan Jakhar (Jawaharlal Nehru University)

14:00 Near Resonance Polarization Modulation (NRPM), a Novel Method for High Precision Beam Energy Measurement in Storage Rings

We propose Near Resonance Polarization Modulation (NRPM), a novel method for high-precise beam energy measurement in storage rings. In this technique, a constant-frequency AC kicker is applied near the spin precession frequency, driving the beam spins coherently. The spin tune can be reliably extracted from the time-dependent polarization signal, enabling a very high-precision determination of the beam energy. Its performance has been demonstrated using the Future Circular Collider e+e- (FCC-ee) Z-pole lattice, exploring a range of configurations including AC kicker strengths and initial polarization levels. The method exhibits robustness against lattice imperfections. Compared to the traditional resonant depolarization (RDP) technique and the free spin precession (FP), NRPM offers significantly improved precision, greater tolerance to systematic uncertainties, and simplified operational procedures. Beyond the FCC-ee case study, NRPM is broadly applicable to high-precision energy determination in modern storage rings. The superior precision offered by this technique will significantly advance the state-of-the-art in beam energy measurement, with critical applications in high-energy physics and the measurement of fundamental constants.

Speaker: Yi Wu (École Polytechnique Fédérale de Lausanne)

14:00 Neural Network-Based Amplitude Feedforward Control Algorithm for LLRF Systems

In free-electron laser facilities, the amplitude-phase stability of the microwave pulses driving the electron beam is a key factor determining beam energy spread. Aiming at the long bunch train operation mode, this paper proposes a neural network-based amplitude feedforward control for low-level radio frequency (LLRF) systems to suppress intra-pulse amplitude fluctuations. The algorithm has been validated at the output of a solid-state amplifier (SSA): under four randomly selected vector modulator (VM) output configurations, the average intra-pulse amplitude flatness (RMS) was reduced from 1.208% to 0.398%, and the average peak-to-peak variation was reduced from 4.683% to 1.353%, demonstrating a significant compensation effect.

Speaker: Prof. Xiaofang Hu (University of Science and Technology of China)

14:00 Non-linear phase space tuning for in-flight Fragment Separators

Next generation in-flight fragment separators like the Super-FRS are built with large apertures to accept high momentum spreads. The wide beam and momentum variation gives rise to large aberrations from non-linear effects, if not suppressed precisely.
Models and simulations are able to predict most effects, but to achieve the highest performance, fine tuning of the ion optics with beams, based on measured aberrations for the machine is needed.

While the main focal planes provide single particle tracking to measure the phase space, the target area instrumentation can only provide coarse information about the overall distribution of the beam. This poses a challenge, as knowledge about the polynomial order of the phase space distortion (in terms of transfer maps) enables a much faster optimization.

In this setting, we used a normalizing-flow-like approach, to find an invertible symplectic kick-rotation-* map, which transforms the measured data into an initial distribution, to extract a possible transfer-map and determine the distortions by order.

Integrated in the Generic Optimisation Frontend and Framework (Geoff), the method was validated in simulations and with a multiple charge state uranium beam at GSI’s fragment separator (FRS), by fine-tuning even significantly detuned optics.

Speaker: Daniel Kallendorf (Technical University of Darmstadt, GSI Helmholtz Centre for Heavy Ion Research)

14:00 Non-linear resonance feed-down - a new technique for correcting high order errors in the LHC

Optics errors from the interaction points of the LHC, where β is most strongly squeezed, can significantly impact machine performance and protection. In anticipation of the HL-LHC, correction strategies extending up to dodecapole order are being targeted. Direct measurement of high-order resonance driving terms (RDTs) remains challenging, however. Applying crossing angle orbit bumps in the experimental insertions induces feed-down from higher-order errors, increasing the magnitude of lower-order RDTs. Leveraging this effect, a novel correction scheme based on RDT feed-down was implemented for the first time in 2025. Skew-octupole errors were successfully corrected, which enabled optics measurements at the collisions working point, down to an unprecedented level of β=18cm. Measurements of feed-down from dodecapole errors, to decapole RDTs were also achieved, opening a practical pathway to efficient corrections of very high-order optics errors.

Speaker: Sasha Horney (European Organization for Nuclear Research)

14:00 Nonlinear Dynamics study from Coupled Beam–Beam and Space-Charge Effects in a Realistic Collider Lattice

Beam–beam interactions are well known to limit the performance of high-energy hadron colliders, as they can degrade beam quality and reduce particle lifetime. When the strengths of the beam–beam and space-charge forces become comparable, as in high-intensity, mid-energy colliders, their interplay results in complex nonlinear dynamics and the excitation of resonances.

In this project, we perform GPU-enabled simulations, motivated by the forthcoming Electron–Ion Collider (EIC), to study the combined effects of beam–beam and space-charge interactions within a realistic accelerator lattice. In support of this endeavor, we have developed a preliminary 2.5D space-charge symplectic model incorporating self-consistent space-charge forces and the complete magnetic lattice. This model enables the study of long-term nonlinear dynamics, which is essential for achieving high average luminosity.

Speaker: Helena Alamprese (Facility for Rare Isotope Beams)

14:00 Nonlinear Plasma Wakefield Perturbation Using Square Gaussian Beam in Uniform Plasma Distribution

Nonlinear plasma wakefield excitation by an ultra-relativistic square Gaussian beam is simulated using FBPIC code. The beam interaction with the background plasma electrons revealed blowout cavity formation. As the beam propagates further into the plasma, blowout cavity elongation along the beam propagation direction was observed. The corresponding electromagnetic field components excited within the plasma wake generated at different iteration stages showed impressive field magnitude. The magnitude of the longitudinal electric field gradients at two different iteration stages is observed in excess of 500GV/m and several TV/m scale levels respectively. Also, the azimuthal magnetic field components is observed to be in excess of 60MT and 47MT levels. The radial electric field and net focusing field components were also assessed as well.

Speaker: Gangtak Nanpon (Joseph Sarwuan Tarka University Makurdi)

14:00 Numerical Quality Factor Statistics of an Inhomogeneously Coated SRF Cavity

Bulk niobium (Nb) is the standard material for superconducting radiofrequency (SRF) cavities, due to its high critical temperature and high critical magnetic field among pure metals. The performance of these cavities has, in recent years, approached their theoretical limits [1]. The superconductor-insulator-superconductor (SIS) multilayer approach offers
an alternative by using a thin superconducting coating, such as Nb3Sn, with higher critical magnetic field to shield the bulk superconductor from accelerating fields [2].

In our work, we model the SIS multilayer by reducing it to a surface impedance using a first-order Leontovich boundary condition, compatible with finite element methods. We then treat the coating thickness as a Gaussian random field, yielding a spatially inhomogeneous surface impedance. We present the results of a Monte-Carlo simulation
performed on a standard 9-cell 1.3 GHz TESLA cavity [3]. This simulation is used to determine statistical properties of quantities of interest, such as the quality factor, and is repeated for different correlation lengths in the Matérn kernel.

[1] A.-M. Valente-Feliciano, Superconducting RF materials other than bulk niobium: a review, Supercond. Sci. Technol. 29(11) 113002, 2016.
[2] A. Gurevich, Enhancement of rf breakdown field of superconductors by multilayer coating, Appl. Phys. Lett. 88(1) 012511, 2006.
[3] R. Wanzenberg, Monopole, dipole and quadrupole passbands of the TESLA-cell cavity, DESY, 2001.

Speaker: Aaron Gobeyn (Technical University of Darmstadt)

14:00 Numerical Study of an X-ray Compton Source Driven by Laser Plasma Acceleration at LAPLACE-HC Facility

Laser-driven Compton sources have emerged as a promising compact method for producing X-ray radiation with femtosecond pulse duration. They offer adjustable energy and bandwidth that can be controlled by the parameters of the electron beam and the colliding laser pulse. In addition, the transverse source size can be as small as a micrometer, making such sources of interest for high resolution X-ray radiography. At LOA, the LAPLACE-HC$*$ project aims to use a laser-plasma accelerator (LPA)$**$ to drive an Inverse Compton Scattering Source (ICS)$***$, producing tunable X-ray pulses in the 10-100’s KeV range and running at 100 Hz. LAPLACE-HC has recently completed the commissioning of its first phase and with a future upgrade coming, the laser energy should reach the Joule level, in 25 fs laser pulses, allowing the production of 100’s of MeV electron beams at 100 Hz. In this work, we present numerical simulations of the performance of the future ICS source using LAPLACE-HC laser beam parameters.

Speaker: David El Khoury (Centre National de la Recherche Scientifique, Laboratoire d'Optique Appliquée, Institut Polytechnique de Paris)

14:00 Off-axis hollow-channel plasma tailoring for generating two-color x-ray free-electron lasers

Plasma-wakefield-based acceleration offers a route to realize compact X-ray free-electron lasers, but its application is currently limited by beam quality. Two-color X-ray FEL pulses provide a powerful tool for probing ultrafast dynamics. Here we propose a scheme for generating such pulses by using an off-axis elliptical hollow-channel plasma to tailor the electron-beam phase space while preserving its quality. In this approach, the plasma wakefield imprints a time-dependent transverse tilt along the bunch, while the elliptical channel geometry effectively suppresses the quadrupole wakefield and minimizes the induced mismatch. This enables fresh-slice lasing control at different wavelengths in two undulator sections. Simulations show the feasibility of generating femtosecond-scale, high-power two-color pulses with tunable temporal separation at the Shanghai Soft X-ray Free Electron Laser facility.

Speaker: Haiyang Li (Shanghai Institute of Applied Physics, Chinese Academy of Sciences)

14:00 One Possible Approach for Intrabeam Scattering Calculation of Arbitrary Phase Space Distributions

Traditional analytical models for intrabeam scattering (IBS) typically assume a Gaussian beam distribution in phase space. In this paper, we present an extended analytical IBS model that employs Hermite-Gaussian polynomials as basis functions to calculate the IBS diffusion coefficient for arbitrary phase space distributions. The generating function method is adopted to simplify the relevant calculations into a numerically solvable integral form. This approach retains the efficiency inherent to analytical models while ensuring calculation accuracy for non-Gaussian beam distributions.

Speaker: Wenxuan Wu (Tsinghua University)

14:00 Online Performance Evaluation and Anomaly Detection of Beam Position Monitor System at HEPS

Beam Position Monitors (BPMs) are essential for the commissioning and stable operation of fourth-generation synchrotron light sources such as the High Energy Photon Source (HEPS). Building on the theoretical beam–electrode response of circular‑section button BPMs, we extract a set of channel‑specific coefficients from in‑situ BPM data. These coefficients remain nearly constant under varying beam positions, making them sensitive indicators of the BPM system’s health. We have developed an online performance evaluation framework that monitors these coefficients for each BPM channel, enabling the detection of gain errors and slow drifts through statistical outlier analysis and continuous trend tracking. Initial implementation in the HEPS beam measurement system has demonstrated rapid and accurate identification of abnormal BPM behavior. To further enhance diagnostic capability, machine‑learning models for anomaly detection are under active development.

Speaker: Youpeng Xie (Institute of High Energy Physics, Chinese Academy of Sciences)

14:00 Online Reinforcement Learning for Stripper Foil Aging Compensation at the CERN Low Energy Ion Ring

Stripper foil degradation at the CERN Low Energy Ion Ring (LEIR) poses a significant challenge for beam operations. As the heavy ion beam passes through the stripper foil at the end of the injecting linac, the foil degrades over time, altering the beam energy distribution and reducing the achievable accumulated intensity in the ring. Addressing this operational limitation using traditional control approaches is challenging due to the complex, multi-dimensional nature of the multi-turn injection process. This paper presents a reinforcement learning-based controller to compensate for foil degradation and maintain ring performance. The controller observes longitudinal Schottky spectra encodings and time-of-flight measurements from the linac to adjust the ramping and debunching cavity phases, and electron cooler gun and orbit bump in real-time. We demonstrate that pre-training the agent in a data-driven surrogate model significantly improves both controller performance and sample efficiency during deployment.

Speaker: Borja Rodriguez Mateos (European Organization for Nuclear Research)

14:00 Optics Design of a Compact Synchrotron for a Proton-Helium Therapy Facility

Under the framework of the SSRF proton-and-helium therapy facility project, a compact synchrotron with a 28-meter circumference has been designed for the generation of high-intensity proton and helium beams. To achieve the high-dose-rate design objective, the optics design of this synchrotron has been further optimized. This optimization successfully reduced the maximum value of the envelope function, enabling a substantial increase in the maximum number of accumulable particles. Concurrently, the vertical beam-stay-clear in the dipole magnets was constrained to ±20 mm, fulfilling the key design requirement for the 2.4 T high-field dipole magnet. Furthermore, particle tracking simulations incorporating space charge effects were conducted for both proton and helium ion beams. The analysis of the tune shift and spread at the end of injection and after bunching demonstrated the dual-particle compatibility and confirmed the feasibility of the compact design.

Speaker: Yixing Lu (Shanghai Synchrotron Radiation Facility)

14:00 Optimal Field Profile in Longitudinal-Gradient Superbend Magnets for the Hefei Advanced Light Source via Multi-Objective Optimization

The Hefei Advanced Light Source (HALF) covers the VUV to soft X-ray range and plans to replace two conventional 0.9 T B4 dipoles in the storage ring with 6 T superbends to extend the photon-energy reach. Increasing the peak field while keeping the field integral unchanged leads to significant changes in the field profile, which may affect the storage-ring optics and beam parameters. To identify a field profile that preserves machine performance, this work applies a multi-objective genetic algorithm to optimize the longitudinal field distribution of the superbend. The resulting profile reduces the impact of the enhanced peak field on lattice performance and provides guidance for the magnetic design and implementation of the superbend for HALF.

Speaker: Jincheng Xia (University of Science and Technology of China)

14:00 Optimisation Techniques for Integrated Luminosity with and without $\beta^\ast$ Levelling for a circular collider with examples from the CERN LHC

The main performance indicator of a particle collider is the integrated luminosity. It depends not only on operational efficiency, but also on a range of beam parameters to be optimised to enhance performance. It is common to operate a collider with decaying luminosity, due to beam burn-off. However, the planned luminosity upgrade of the LHC (HL-LHC) is based on luminosity levelling: a time variation of colliding-beam offset, crossing angle and $\beta^\ast$ is used to keep luminosity constant over a certain lapse of time. The operating experience on luminosity levelling is gathered at the LHC, which uses different levelling strategies. In this work, we investigate optimisation strategies to maximise integrated luminosity without and with $\beta^\ast$ levelling. Monte Carlo simulations of years of physics runs have been performed with and without optimisation approaches. The key physical parameters are derived from a detailed analysis of the data collected at the LHC during the Run~2 and Run~3 periods. These findings provide valuable information for improving future LHC operational strategies and preparing for forthcoming collider configurations in the HL-LHC era.

Speaker: Maria Aquilina (University of Malta)

14:00 Optimization of Magnetic Field Parameters in AMD for Enhanced Positron Yield

The longitudinal magnetic field profile of the Adiabatic Matching Device critically determines positron capture efficiency. While traditional designs prioritize the long adiabatic decay, this study investigates the often-overlooked non-adiabatic rise from the target exit field $B_0$, to the peak field $B_{\text{peak}}$. By systematically varying $B_0$, $B_{\text{peak}}$,, and the rise distance Z, we analyzed their impact on positron yield. Results demonstrate that the magnetic field gradient in this initial phase is pivotal. Specifically, optimizing the $B_0$/$B_{\text{peak}}$ ratio and minimizing the rise distance significantly enhances capture efficiency. These findings provide essential optimization strategies for high-performance positron sources.

Speaker: xin xu (University of Science and Technology of China)

14:00 Optimization of Multi Turn Injection into the HIT Medical Synchrotron

Previous work has shown that the efficiency of multi-turn injection (MTI) is heavily influenced by the injection bumper curve. By implementing a neural network with a custom loss function based on the given machine limitations from the HIT Medical Synchrotron, the curve was optimized via a sequence of third-order polynomial functions by online training. Experiments with variable epoch lengths demonstrated an improved current output with up to a 20% increase over the previously established maximum. These results underscore the importance of bumper curve optimization in maximizing synchroton efficiency, demonstrating a more effective alternative to a curve tuned by operators regarding time spent and outcome.

Speaker: Corinna Steffen (Heidelberg Ion Beam Therapy Centre)

14:00 Optimized design of a C-band 100 MeV electron LINAC for FLASH radiotherapy

Electron LINACs are key tools for radiotherapy. Conventional low-energy ones can treat only superficial tumors. Achieving Very High Energy Electrons (VHEE, >100 MeV) enables treatment of deep-seated tumors. Furthermore, electrons are well-suited for delivering Ultra-High Dose Rates (UHDR) required for FLASH therapy, which improves healthy-tissue sparing. Combining VHEE and FLASH in a hospital environment represents an important step forward for Radiotherapy.
In the context of the SAFEST project at Sapienza, this work presents a compact and cost-effective accelerator layout capable of delivering hundreds of nC at 100 MeV within tens of pulses over 1 ms of irradiation. The design emphasizes efficient RF power usage through high-efficiency C-band structures and a pulse compressor. Beam dynamics simulations and low-power RF tests validate the approach. A strong focus is placed on flattening the compressor signal, which must remain stable over 1 mus to accommodate electrons from a triode thermionic gun, a compact and economical source for this accelerator. The resulting 3-m linac, powered by a single 20-MW klystron, shows strong potential for future hospital-based FLASH VHEE treatments.

Speaker: Stefano Farina (Sapienza University of Rome)

14:00 Optimizing Momentum Aperture in Korea-4GSR via Higher-Order Chromaticity and W-function Analyses

Recent upgrades of synchrotron light sources aim to achieve ultralow emittances, requiring strong magnet strengths that inevitably lead to severe nonlinear effects. Consequently, securing a sufficient Touschek lifetime has become a critical challenge for storage rings, including the Korea-4GSR. In this study, we performed systematic scans of tune and chromaticity to identify optimal working points and characterize lattice properties in the presence of nonlinearities and errors. Through these scans, we observed a distinct dependency of the Touschek lifetime on chromaticity settings. We explain the reason for the optimal chromaticity range by analyzing Momentum-Dependent Tune Shift (MDTS) curves and higher-order chromaticity effects.
Nonetheless, directly optimizing the lifetime is computationally intensive because it requires calculating the momentum aperture along the entire ring. Hence, to overcome this challenge, we propose an efficient indirect optimization method based on the analysis of W-function fluctuations.

Speaker: Junha Kim (Pohang Accelerator Laboratory, Ulsan National Institute of Science and Technology)

14:00 Optimizing the Design and Data Processing of Tunnel Control Network for Particle Accelerator

With the advancement of large-scale scientific projects, engineering control networks face higher demands. This study focuses on particle accelerator tunnel control networks, addressing key challenges in automated design, data fusion, and deformation prediction. Three main contributions are presented:(1) Automated simulation of laser tracker networks using Spatial Analyzer's Measurement Plans, enabling automated station planning and Monte Carlo simulations for design evaluation. (2) Heterogeneous data fusion, integrating laser trackers with precision instruments. For elevation accuracy, differential leveling models are implemented. For planar accuracy, distance-constrained adjustment algorithms are developed. (3) Machine learning-based deformation prediction using long-term observation data. An integrated workflow establishes multiple prediction models including neural networks for 3D coordinate forecasting, supporting maintenance decisions. Demonstrated at Hefei Advanced Light Facility, this research provides transferable solutions for large-scale engineering applications, balancing methodological robustness with practical implementation.

Speaker: Enchen Wu (University of Science and Technology of China)

14:00 Parallel Quadrupole Beam-Based Alignment for FCC-ee

The Future electron-positron Circular Collider (FCC-ee) is a proposed lepton collider for high-energy particle physics succeeding the High-Luminosity Large Hadron Collider (HL-LHC). Its ambitious design goals demand excellent orbit and optics control and, therefore, set strict limits on alignment tolerances. Beam-based alignment (BBA) is used to relax the mechanical alignment tolerances by determining the offset between the magnet and the measured beam position. Orbit correctors steer the particle beam towards the determined positions of the magnetic centre and thus reduce the effective quadrupole misalignment. A parallel BBA technique is compared for the Global Hybrid Correction (GHC) and Local Chromaticity Correction (LCC) lattices for FCC-ee using Xsuite simulations.

Speaker: Christian Goffing (European Organization for Nuclear Research)

14:00 Performance analysis of the Mach-Zehnder interferometer using synthetic interferograms

In this work, we assess the performance and limitations of Mach-Zehnder interferometry for plasma diagnostics using a fully synthetic, numerically generated dataset. We explore regions of parameter space that are difficult to access experimentally, including fringe behaviour under different plasma density profiles, the dynamic range of measurable phase shifts, and the resolution limits for low-density plasmas. By introducing controlled phase errors and noise, we quantify the robustness of common phase retrieval and phase unwrapping algorithms and identify the conditions under which these methods succeed or fail. Our results provide practical design guidelines for optimising interferometric measurements across a wide range of plasma conditions.

Speaker: Fatimah Alharthi (University of Manchester)

14:00 Phase Space Tomography Constrained by the Vlasov–Fokker–Planck Equation Using EOSD Diagnostics at KARA

This study presents the first experimental application of longitudinal phase space tomography constrained by the Vlasov–Fokker–Planck equation (VFPE) using electro-optical spectral decoding (EOSD) diagnostics at the Karlsruhe Research Accelerator (KARA). The EOSD measurements are modeled as the convolution of the system’s impulse response with the charge density profile at the time of acquisition. Combining this model with the VFPE we formulate a partial differential equation (PDE)-constrained optimization framework for the inverse tomography.

Using this framework, we successfully reconstruct the longitudinal phase space of the electron bunch across different dynamical regimes, ranging from the stable state to the onset of micro-bunching. The reconstructed phase space density reproduce expected features of the bunch evolution and allow us to compute the corresponding coherent synchrotron radiation (CSR), which exhibits clear changes correlated with the reconstructed micro-structures. Overall, the results demonstrate that the VFPE-constrained approach, combined with a detailed EOSD forward model, provides a physically consistent reconstruction of the phase space dynamics from EOSD measurements.

Speaker: Felipe Donoso (Karlsruhe Institute of Technology)

14:00 Photoemission study of nanostructured plasmonic photocathodes

We present a simulation study of a nanostructured plasmonic copper photocathode for use in the new photoinjector that is presently being developed for the high-duty-cycle operation upgrade of the European XFEL. The simulations are based on a spatially resolved photoemission model using the Fowler-DuBridge formalism and including the Schottky effect induced by the accelerating field on the cathode surface. Particle-in-cell simulations are performed to evaluate the phase-space of the beam in the near-cathode region. It is shown that while quantum efficiency is improved, photoemission from the plasmonic cathode leads to a substantially increased transverse emittance and higher energy spread of the beam compared to the case of a flat copper surface. Space-charge effects remain moderate for the operating bunch charge considered in the study.

Speaker: Margarita Bulgacheva (Technical University of Darmstadt)

14:00 Photoinjector Emittance Optimization using Latent Laser Pulse Representations

We present a beam dynamics study aimed at optimizing the transverse emittance of electron bunches in a photoinjector, motivated by the performance requirements of Free-Electron Lasers. The study is conducted using the accelerator configuration of the Photo Injector Test Facility at DESY in Zeuthen (PITZ), with the overarching goal of developing emittance optimization strategies for the European XFEL photoinjector. To this end, we perform large-scale beam dynamics simulations using the simulation code ASTRA, systematically sampling from a low-dimensional latent representation of temporal laser pulse profiles. This latent space is learned from a broad set of physically plausible pulses using a Wasserstein Autoencoder (WAE), enabling compact and structured exploration of pulse shape variations. The ability to efficiently sample from this representation supports targeted emittance studies that would be computationally prohibitive in the original high-dimensional shaping parameter space. For each simulation, beam quality metrics such as normalized projected emittance and slice mismatches are recorded. The study reveals meaningful correlations between latent coordinates and beam quality, demonstrating the utility of WAE-based representations in guiding laser pulse design. We briefly outline future directions involving neural surrogate models to accelerate beam emittance optimization.

Speaker: Alexander Klemps (Hamburg University of Technology)

14:00 PIC simulation and characterisation on the single-charge ECR ion source in the ALISES 3 experimental ion source

We present here simulations of ALISES 3, a single-charged Electron Cyclotron Resonance (ECR) ion source developed at CEA, and comparisons with experiments. This source can produce high-intensity proton beams. Using commercial simulation tools, we simulate the key physical parameters such as the RF, magnetic, and electrostatic fields, as well as particle dynamics. These simulations describe particle behavior and interactions (collisions, RF heating, ionization processes…). We aim at proposing a comprehensive numerical model of a single-charge ECR source. These developments will enable the optimization of key ECR ion source parameters, including beam intensity, source lifetime, and emittances. Experiments with the actual source are presented at the end.

Speaker: Mathias Barant (Commissariat à l'Énergie Atomique et aux Énergies Alternatives)

14:00 Post-processing of additively manufactured pure copper RFQ elements

The utmost design freedom of additive manufacturing can be leveraged to fabricate complex particle accelerator components, such as the radiofrequency quadrupole (RFQ). However, the high surface roughness typical of as-printed parts represents a major barrier to the integration of additive manufacturing technologies into established fabrication workflows. This work investigates finishing processes aimed at improving the surface quality of additively manufactured RFQ components, with a focus on the hard-to-access vane tip region. A dedicated mock-up was developed, consisting of a copper vane representing a one-quarter RFQ section, mounted in a plastic holder to replicate the full part. This setup allows the copper part to be removed after each treatment step to measure material removal and assess effects on vane modulation, surface roughness, and overall geometric accuracy. Both mechanical mass finishing with abrasive media and chemical polishing were examined, applying each treatment in multiple intermediate steps. Comprehensive surface characterization was conducted after each finishing stage by means of profilometry, 2D and 3D roughness measurements, and 3D scanning to determine correlations between process parameters and resulting surface quality. The objective is to develop an optimed finishing strategy capable of achieving the surface quality and geometric accuracy required by RFQ and other advanced particle accelerator components.

Speaker: Tobia Romano (Politecnico di Milano, Riga Technical University)

14:00 preliminary physics design of 1.3 GHz superconducting electron gun

Conventional electron guns face limitations in achieving the required accelerating gradients while maintaining satisfactory beam quality for our application. To overcome this challenge, we have developed a superconducting radiofrequency (SRF) electron gun. This gun is specifically designed and operated at a high cathode gradient of 30 MV/m. We present a comprehensive evaluation of its key performance characteristics. This includes detailed analyses of its RF properties and critical mechanical behavior under operational conditions. Specifically, we report on the helium pressure sensitivity, Lorentz force detuning, tuning sensitivity, and modal analysis. These results demonstrate the feasibility of the SRF gun design and provide essential insights into its operational stability and performance at the demanding target gradient of 30 MV/m, paving the way for high-brightness beam applications.

Speaker: XiongHao Yuan (Shanghai Institute of Applied Physics, Chinese Academy of Sciences)

14:00 Preliminary Study on Beam-Beam Interaction with Multi-physics Effects in the Super Tau-Charm Facility

To achieve its design luminosity of $1 \times 10^{35} \text{cm}^{-2}\text{s}^{-1}$, the Super Tau-Charm Facility (STCF) currently under design in China employs the crab-waist collision scheme with an ultra-low $\beta_y^*$. While this configuration enables a beam-beam parameter of $\xi_y \sim 0.1$, it also increases sensitivity of luminosity to beam-beam effects and their interplay with additional physics processes. This paper presents beam-beam simulation studies that include several selected multi-physics effects, such as lattice nonlinearities, wakefields, and space-charge forces, to evaluate their impact on the luminosity performance of the STCF collider. A GPU-accelerated strong-strong simulation framework is
employed to incorporate these effects in a self-consistent manner. Preliminary results indicate that key parameters, including $\beta_x^*$ and the synchrotron tune $\nu_s$, must be carefully optimized to improve the tolerance to these multi-physics effects. The study also highlights the importance of appropriate working-point selection to suppress detrimental beam instabilities and maintain stable collisions.

Speaker: Sangya Li (University of Science and Technology of China)

14:00 Preliminary study on the collective effects in the storage ring‑based coherent light source

The storage ring–based coherent light source (SRCLS) operates under extreme conditions: ultra‑low emittance, short bunches, high current, and strong damping. In such a regime, collective effects become critically important. This paper presents a preliminary study of the key collective effects in the SRCLS, including the Touschek effect, intra‑beam scattering, resistive‑wall impedance, and ion effects. Through numerical simulations and theoretical analysis, the impact of these effects on beam dynamics is evaluated. The results demonstrate that stable operation of the SRCLS can be achieved under the designed parameters.

Speaker: Yanxu Wang (University of Chinese Academy of Sciences)

14:00 Progress of developing the bunch-by-bunch feedback system for the CSNS RCS

The Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) is planned to upgrade its beam power from the current 100 kW to 500 kW in the CSNS-II phase. However, significant beam-intensity-dependent transverse instability has already been observed during routine 100 kW operation. As the beam power increases further, this instability is expected to become much stronger. To effectively suppress the coherent transverse oscillations induced by impedance wakefields and injection errors, a bunch-by-bunch transverse feedback system is essential. This paper evaluates the performance of the digital filter and the complete bunch-by-bunch feedback chain, from the front-end electronics through the power amplifier to the strip-line kicker. Feedback system simulations are performed to optimize key parameters, providing critical guidance for the design, commissioning, and future operation of the system.

Speaker: Weiwen Chen (Institute of High Energy Physics, Chinese Academy of Sciences)

14:00 Properties of trapped ions with the SCRIT method at the SCRIT electron scattering facility at RIKEN

The SCRIT electron scattering facility at RIKEN RI Beam Factory is a unique facility dedicated to electron scattering off unstable nuclei. The SCRIT (Self-Confining Radioactive isotope Ion Target) method utilizes the phenomenon of ion trapping within an electron storage ring. This innovative technique forms a target by replacing the residual gas in the ring with incident radioactive isotope (RI) ions. The circulating electron beam provides a self-focusing force, enabling trapping of RI ions along the beam axis. Consequently, the SCRIT method facilitates the creation of an unstable nuclear target within the electron storage ring, realizing the long-anticipated electron scattering off unstable nuclei.

For achieving high luminosity, it is crucial to investigate the dynamics and properties of the trapped ions, as various complex processes govern their motion within the SCRIT ion trap. Our recent studies focused on measuring the energy distribution of the trapped ions. The results revealed a clear correlation between the ion energy and their total trapped charge, indicating a significant space charge effect. More detailed investigations are currently underway, including the measurement of the distribution of ion charge states and the emittance distribution for each specific charge state.

In this contribution, we report on the current status of studies concerning the ion trap properties and prospects of the SCRIT electron scattering facility.

Speaker: Mr Yuta Kikuchi (Saitama University)

14:00 PROSPECTS FOR SYNCHROTRON XRF CHARACTERIZATION OF LITHIUM IN PYRITE-BEARING SHALES OF NORTH-EAST INDIA

The global transition toward sustainable energy technologies has intensified the search for unconventional lithium resources, including pyrite-bearing organic-rich black shales. This work evaluates the potential application of synchrotron X-ray fluorescence (SXRF) and coupled SXRF–XRD mapping for investigating lithium occurrence in shale systems of North-East India. Conventional analytical methods such as XRF and ICP-based techniques exhibit limitations in detecting low-Z elements such as lithium while preserving spatial and mineralogical information. Synchrotron radiation provides high brilliance, tunable excitation energy, and micron-scale spatial resolution that may enable high-sensitivity elemental mapping and phase correlation in heterogeneous geological materials. The proposed methodology integrates synchrotron XRF elemental imaging with X-ray diffraction phase identification to investigate lithium association with clay minerals and pyrite. This study presents a conceptual framework for applying accelerator-based characterization techniques to unconventional lithium resource exploration.

Speaker: Zahid Mamud (The Assam Royal Global University)

14:00 Quantum Accelerator & Wiggler using Extreme Plasmons Excited in Nanofabricated Materials: E-339 at SLAC

Extreme plasmons* that are nonperturbative excitations of quantum electron gas inherent in conductive, nanofabricated materials, open unprecedented PetaVolts per meter fields. PV/m fields enable concepts such as a collider on a chip, nano-wiggler based gamma-ray lasers, opening the vacuum using high-field polarizability etc.

This technique that relies on emergent properties of the conduction electrons is being prototyped as part of our experimental program using E339 at SLAC. In experiments, we controllably excite extreme plasmons that not only access large fields but also preserve the material structure from irreversible damage, making a quantum accelerator ** and PV/m plasmonics*** realizable. Numerous unexplored aspects of quantum dynamics underlying large-amplitude, collective oscillations of the quantum electron gas work in unison to allow access to quantum coherence limit, $E_Q=0.1 \sqrt{n_0 [10^{24} \rm cm^{-3}]} ~ \rm PVm^{-1}$, where $n_0$ is tunable using techniques in material science.

Here we present the experimental design and initial results that indicate the excitation of ten GV/m fields and material resilience over thousands of shots upon careful tuning of appropriately structured, doped semiconductors****. A semiconductor tube that is closely matched and configured to collisionlessly interact with FACET-II beams sustains surface crunch-in plasmons critical for stable excitation as well as tunability that paves the way to significantly higher fields.

Speaker: Mr Kalyan Tirumalasetty (University of Colorado Denver)

14:00 Rate capabilities of radiation monitors based on diamond detectors

Diamond detectors are widely used in harsh radiation environments due to their intrinsic radiation hardness. At high particle fluxes, single-particle measurements in counting mode are challenging because of pile-up, requiring a transition to current measurement. In this study, a 500 MBq $^{90}$Sr beta source was used to investigate the limitations of the counting mode and the transition to current mode with diamond detectors. A dedicated readout was implemented using a CIVIDEC ROSY$^®$ data acquisition system, with a simultaneous counting and current mode. Low-noise CIVIDEC charge-sensitive spectroscopic amplifiers with FWHM of 10 ns, 30 ns, 50 ns, 100 ns, and 180 ns were compared. The correlation between the measured count rates and the current was studied.

Speaker: Julian Melbinger (TU Wien, CIVIDEC Instrumentation (Austria))

14:00 Real Time Longitudinal Beam Measurements in the Crocker Nuclear Laboratory Isochronous Cyclotron

The UC Davis Crocker Nuclear Laboratory (CNL) operates a 76-inch isochronous cyclotron dating to the 1960s, with limited internal beam diagnostic instrumentation. Direct measurements of the Cyclotron beam are challenging due to the harsh environment, including high radiation, strong magnetic fields, RF interference, and spatial constraints. A novel beam probe has been developed for longitudinal bunch structure and phase measurements in a 15 mm square transverse profile with 16 independent pixels. The probe consists of a segmented fast plastic scintillator array coupled via fiber optics to external Silicon Photomultipliers (SiPMs), mounted on a radially translating probe. Bunch length and phase information are measured and analyzed in real time, with continuously updating visualizations available to operators and to downstream real-time analysis tools. Additionally, the collected data are archived for offline analysis, supporting the development of simulations for the CNL Cyclotron. The Fast Beam Probe opens the door to improved beam stability, more accurate modeling, and future integration with automated control systems at CNL.

Speaker: Logan Knudson (University of California, Davis)

14:00 Real-Time Reconstruction of Longitudinal Phase-Space Distribution in Hadron Beamlines and Synchrotrons

Real-time measurement and control of the longitudinal momentum spread during the beam transfer from the transfer channel (TK) into the SIS18 synchrotron is needed for the low-loss high-intensity operation. For this purpose, two Feschenko-type beam shape monitors (BSM) will be installed in TK. This will enable the single-pass measurements and real-time reconstruction. Simulations using a differentiable tracking scheme will be applied. The underlying beam dynamics model is simplified for computational efficiency, but retaining the key aspects of space-charge and beam loading effects, while providing a sufficient reconstruction accuracy.

Speaker: Sergei Sherstiuk (Technical University of Darmstadt)

14:00 Real-Time Tomography of Synchrotron Longitudinal Phase Space Based on Spatio-Temporal Neural Networks

Accurate acquisition of the longitudinal phase space distribution is crucial for synchrotron optimization, but traditional tomography requires minutes per reconstruction, preventing real-time diagnostics. To resolve this, we propose a novel spatio-temporal neural network integrating 1D Convolutional Neural Networks (CNN) and Transformers. This hybrid model achieves end-to-end continuous reconstruction from 1D beam projections to 2D phase space dynamic evolution.
The network is trained on a high-fidelity dataset generated via the BLonD code. It incorporates nonlinear space charge effects based on the machine parameters of the Xi'an 200MeV Proton Application Facility (XiPAF). Results demonstrate the model accurately restores complex phase space topological structures. It effectively captures both high-density cores and low-density edge halos. The model achieves a longitudinal line density projection error under 1% in simulations and under 2% using real Fast Current Transformer (FCT) measurements from the XiPAF facility.
Furthermore, the framework delivers single-frame inference times of 0.109 ms on a GPU and 4.557 ms on a standard CPU. This sub-millisecond processing speed successfully crosses the engineering threshold for online real-time diagnostics. Ultimately, it establishes a reliable new continuous imaging paradigm for automated beam real-time feedback control in high-intensity accelerators.

Speaker: Yixuan Luo (Tsinghua University)

14:00 Real-Time X-ray Beamline Surrogate Modeling via a Physics-Informed Log-Manifold Learning Framework

Wave-optical simulation of undulator radiation through X-ray beamlines is computationally prohibitive, limiting real-time optimization. The high-frequency diffraction structures and extreme dynamic range of focal spot distributions pose significant challenges to conventional surrogate models. We propose a log-manifold surrogate modeling framework that represents intensity distributions in logarithmic space, converting highly nonlinear diffraction structures into low-rank learnable manifolds. With physics-informed OOD-aware Residual method, the model attains less than 1% relative error over the full dynamic range, faithfully reconstructs fine diffraction fringes, and generalizes robustly across beamline configurations. Single prediction takes only milliseconds, yielding thousands of speedup over SRW simulation and enabling real-time surrogate-based beamline optimization. This work demonstrates an efficient path toward real-time digital-twin beamline modeling for fourth-generation light sources, enabling online optimization, rapid parameter scans, and virtual diagnostics.

Speaker: Xuanying Song (Tsinghua University)

14:00 Recent Developments in RF Stabilization at the SPARC_LAB Facility of LNF–INFN

The plasma wakefield acceleration is becoming the most promising acceleration scheme because of its high accelerating gradient and compactness, but it also suffers from unstable operation since the acceleration is accomplished in a short, steep and nonlinear gradient region. This puts forward a very strict synchronization requirement on the subsystems of the entire facility. For the beam-driven scheme, the RF line phase jitter should be less than 20 fs RMS with respect to the facility’s reference master oscillator (RMO). At SPARC_LAB, the RF stabilization technology on RF power stations has been developed for years. These efforts have successfully reduced the phase jitter of the RF line from hundreds of femtoseconds to tens of femtoseconds RMS relative to the RMO. Recent developments on this technology mainly focus on optimizing the fast feedback loop design, together with upgrades of other necessary LLRF components. Dedicated measurements of the prototypes in S-band and C-band both demonstrate reliable and excellent jitter minimization, satisfying the rigid synchronization requirement of beam-driven plasma wakefield accelerators.

Speaker: Xianghe Fang (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati)

14:00 Research status on the ECRIPAC accelerator concept

This study presents the current advancement on our investigation of the Electron Cyclotron Resonance Ion Plasma Accelerator (ECRIPAC), revisiting and greatly expanding this original accelerator concept initially developed in the nineties*. ECRIPAC is an innovative compact plasma device able to generate energetic pulsed ion beams using robust and well mastered electron cyclotron resonance ion source technologies, without requirements for axial RF cavities or powerful laser beams. It relies on the gyromagnetic auto-resonance of plasma electrons in a time growing magnetic field**, followed by the axial acceleration of ions through the plasma space-charge field inside a magnetic field gradient, up to energies close to 100 MeV/A.
The theoretical behaviour of ECRIPAC is summarized. Some preliminary results of kinetic plasma simulations inside a preliminary design of an ECRIPAC machine able to accelerate He2+ ions up to approximately 10 MeV/A are presented. Two sets of simulations are considered, one working with a cylindrical geometry and azimuthal mode decomposition in the open-source code Smilei*** and the other using a 3D geometry in the open-source code WarpX****, providing interesting insights on the plasma behaviour inside the accelerator.

Speaker: Andrea Cernuschi (Laboratoire de Physique Subatomique et de Cosmologie)

14:00 RF Electron Guns with Controlled Longitudinal Dispersion for Attosecond UED

We formulate the design of a UED-oriented RF gun as a constrained longitudinal-dynamics problem and obtain a nonuniform 2.33-cell S-band solution with controlled longitudinal dispersion. The representative solution, (0.4, 0.93, 1), operated near 45 MV/m, brings the phases of maximum energy gain and minimum time of flight (TOF) into near coincidence and thereby yields a well-defined gun dispersion. For the GPT tracking reported here, the beam at the gun exit has a kinetic energy of 3 MeV, an rms bunch length of 100 fs, a charge of 0.1 pC, and a normalized emittance of about 10 nm·rad. With a matched Double Bend Achromat (DBA) beamline, the bunch is compressed to 940 as rms with 10 fC charge at the sample. For RF-amplitude, RF-phase, charge, and magnet-field jitters of 0.05%, 0.2 ps, 3%, and 0.01% rms, respectively, the sample-plane arrival-time jitter is 600 as rms; source-only scans give 518 as rms from amplitude jitter and 167 as rms from phase jitter. These results show that the proposed model provides a direct route to RF guns specifically suited for attosecond UED.

Speakers: Prof. Chao Feng (Shanghai Advanced Research Institute), Qiang Gu (Shanghai Advanced Research Institute, Chinese Academy of Sciences), YUXIN CHENG (Shanghai Institute of Applied Physics, Chinese Academy of Sciences, University of Chinese Academy of Sciences)

14:00 Scenario of Beam-based Alignment with New BPM System for Future Beam Commissioning of 1.3-MW Operation at the J-PARC Main Ring

In the main ring (MR) at the Japan proton accelerator research complex (J-PARC), beam-based alignment (BBA) is essential for precise calibration of beam position monitors relative to quadrupole magnet centers. With the upgrade of the beam position monitor (BPM) system for better precision scheduled in this summer, frequent and accurate BBA will become increasingly important to optics and orbit correction for realizing less beam loss and stable operation. In this study, a fast BBA method is experimentally investigated and compared with conventional approaches. The fast method uses orbit modulation within a single measurement to efficiently extract offset information. Experimental results show that the fast approach achieves alignment accuracy comparable to the conventional method while significantly reducing the required measurement time. These results demonstrate the feasibility of regular beam-based alignment measurements and provide a path toward more precise optics correction in the MR.

Speaker: Yoshihiro Saito (The Graduate University for Advanced Studies, SOKENDAI)

14:00 Simulation Analysis of X‑Ray Pinhole Imaging and Fresnel Zone‑Plate‑Based Beamline for HALF

This work presents a comprehensive simulation study aimed at validating key optical models for X‑ray pinhole cameras and Fresnel zone‑plate (FZP) imaging lines designed for the Hefei Advanced Light Faclilty (HALF). Accurate transverse beam diagnostics are essential for beamline performance, and simplified approximations—such as the square‑aperture pinhole model, Gaussian point‑spread function (PSF), and analytical diffraction models—require rigorous evaluation under realistic conditions.

We perform systematic simulations of a HALF‑configured pinhole camera using both an ideal square aperture (25×25 µm) and a realistic two‑plate tungsten pinhole. Diffraction effects are compared between Fresnel (near‑field) and Fraunhofer (far‑field) regimes by varying source‑to‑pinhole and pinhole‑to‑detector distances. In parallel, a detailed wave‑optical simulation of a Fresnel zone‑plate imaging line is conducted to assess focusing efficiency, spatial resolution, and coherence effects under HALF beam parameters.

This integrated simulation approach supports the optimization of beam‑diagnostic instruments and coherent imaging systems at HALF, ensuring reliable performance from preliminary design to commissioning.

Speaker: Xinru Gao (University of Science and Technology of China)

14:00 Simulation based machine protection for the Super-FRS

Starting in 2027, the Super-FRS will produce and separate rare isotopes for nuclear physics experiments at the Facility for Antiproton and Ion Research (FAIR). To reach isotopes further toward the nuclear drip line, the separator uses heavy-ion beams of higher energy (>1.5 GeV/u) and intensity (>3*10^11 238U/s) compared to previous facilities. These primary beams, as well as the secondary fragment beams produced in reaction targets, can damage detectors along the beamline and may cause quenches in the superconducting magnets. To prevent such scenarios, it is essential to ensure that all beams are correctly separated and stopped in dedicated beam dumps. For this purpose, a machine protection system is being developed to verify every new machine setting required during diverse experimental campaigns. To avoid slowing down machine operation, the system simulates, in near real time, all (fragment) beams for different magnet settings, targets, degraders, and detectors throughout the entire separator. The planned capabilities of this machine protection system and the currently achieved prototype are presented.

Speaker: Jan Wirtz (GSI Helmholtz Centre for Heavy Ion Research, Technical University of Darmstadt)

14:00 Simulation of Dielectric Wakefield Acceleration in Planar Structures at SwissFEL

SwissFEL has two 1 m-long planar dielectric wakefield structures used for dechirping electrons in its hard X-ray beamline, Aramis. Simulations show the structures also support wakefields that can be used to accelerate following particle beams. Here we introduce the dielectric wakefield structures and ECHO2D simulations that show the longitudinal wake potential dependence on structure gap and drive beam length. We present simulations showing the thickness and permittivity of the structures’ dielectric coating determine the location of the accelerating wake potential. Finally, we compare the longitudinal wake potentials generated in the dielectric structures with those in SwissFEL’s planar metallic corrugated structures.

Speaker: Evan Ericson (Paul Scherrer Institute)

14:00 Simulation of plasma dechirper and lens for laser wakefield acceleration

The quality of electron beams produced by Laser Wakefield Acceleration (LWFA), is controlled through laser parameters and plasma density distribution during the injection and acceleration phases, and in some cases, a specific device providing beam selection or shaping to achieve the electron beam quality needed the envisaged application.

A major challenge in the generation of LWFA electron sources is reducing energy and transverse momentum spread to enhance spectral brightness, requiring advanced techniques to optimize beam quality.

We design plasma density profiles to control electron injection and acceleration, specifically to improve the electron beam phase space characteristics in a compact way. This works presents our numerical study using Computational Fluid Dynamics (CFD) and Particle-In-Cell (PIC) simulations. These simulation results are in good agreement with experimental results obtained at Helmholtz-Zentrum Dresden-Rossendorf.

Speaker: Lodewyk Steyn (Laboratoire de Physique des Gaz et des Plasmas)

14:00 Simulation studies for FCC-ee Compton polarimeters

This work focuses on the energy calibration of the FCC-ee and aims to develop precise techniques for ensuring accurate beam energy measurements, essential for improving the precision of electroweak parameter determinations. To do so, resonant depolarisation technique will be employed, requiring the continuous operation of a depolariser and Compton polarimeters for both electrons and positrons beam. Extraction of pilot bunches polarization is realized from the spatial distribution of scattered electrons and photons.
The work explores the determination of Compton-scattering parameters. Preliminary conceptual studies of the fitting procedure required for this extraction are presented here. In addition, studies on the fast extraction of bunch polarisation parameters for each turn in the ring are included, aiming to enable faster, turn-by-turn monitoring of the beam polarisation.

Speaker: JUBA TAMAZIRT (Centre National de la Recherche Scientifique)

14:00 Simulation study for the new collimators of PETRA IV

In accelerators, collimators are used to shape the beam
and protect the machine against damage. They have however
an adverse effect on the beam quality. We present a
trapped-mode analysis of the new collimators for PETRA IV
and their impact on beam dynamics. Wakefield and eigenmode
simulations are used to determine the beam-coupling
impedance of the collimators. From that, the quality factor,
shunt impedance and normalised shunt impedances are extracted.
The results show that higher-order modes make a
significant contribution to the beam-coupling impedance of
the structure. It is shown that geometric modifications can
effectively reduce the beam-coupling impedance. Based on
the found modes, beam stability calculations show stable
behaviour.

Speaker: Pascal Reinhart (Technical University of Darmstadt)

14:00 Simulation Study of the Full Waveguide Design for HiFEL

Hefei infrared Free Electron Laser (HiFEL) facility aims to provide high-quality lasers with wavelengths covering the mid to far infrared range. However, there is an obvious decrease in the output power at long wavelengths. The mode field mismatch and truncation loss at the waveguide to free space region are the main reasons for low output power. We propose a full waveguide design and simulation results suggest that compared to partial waveguide configurations, the full waveguide structure improves the saturated output power in the long wavelength range.

Speaker: Guanzheng Wu (University of Science and Technology of China)

14:00 SMART - a SMall pArticle accelerRaTor on chip

The miniaturization of particle accelerators via Dielec
tric Laser Acceleration (DLA)* offers a route to ultra
compact, cost-effective devices poweredbycommerciallaser
systems. This work explores the extension of DLA technol
ogy—historically focused on electrons—to protons, aiming
to enable "on-chip" sources of high energy hadrons. We
present the design and simulation of a novel microstruc
ture optimized for the acceleration of non-relativistic pro
tons. Key challenges addressed include the management
of phase slippage and the requirement for strong transverse
confinement of heavy particles at low 𝛽. This study aims
to demonstrate the potential for stable acceleration and fo
cusing, validating the pDLA(proton-DLA) ** concept as a
viable candidate for future compact accelerator architectures.

Speaker: Dr Alan Marcia (Fondazione Bruno Kessler, University of Trento)

14:00 Some statistical properties of attosecond SASE FELs

Free electron lasers can now generate xray pulses with durations in the attosecond regime.
Optimal utilization of the short pulses for attosecond science necessitates precise measurement of the pulse durations which there are promising methods to achieve.
However, these are developing experimental techniques, not yet routine procedure.
Until they mature, there is a wealth of information in the measured pulse energies and xray spectra, which are easily obtained.
We show that while this information is insufficient to draw any conclusions about a single shot, with a large enough dataset, the statistics can determine length of the electron bunches, on average.
FEL theory then predicts the distribution of the xray pulse durations.
To achieve this, we extend the classical theory put in place by Saldin and Bonifacio to include short bunches with arbitrary current profiles, deriving integral expressions for some key statistical observables.
The analytical is approach compared to 1D nonlinear simulations, showing good agreement until saturation sets in.

Speaker: Johan Ribbing (Uppsala University)

14:00 Space-based modulating-anode particle accelerator system for controlled wave generation

The aim of this research is to improve the design and physics basis of a modulating-anode electron gun for future space-based electron accelerator missions. Unlike grid-controlled sources, a mod-anode introduces a separate biased electrode between the cathode and main anode, allowing direct control of the accelerating field profile. We investigate how the mod-anode potential shapes the electrostatic landscape, modifies electron emission conditions, and governs beam formation, including current rise time, emittance, and transverse focusing. Using particle tracking and electrostatic simulations, we map how mod-anode geometry, gap spacing, and bias waveform impact phase-space evolution, beam stability, and pulse structure during propagation in free space. Particular attention is given to trade-offs between high modulation depth and the increased voltage required for fast beam switching in the absence of fragile grids. The results define design windows for robust, repeatable, and strongly modulated electron beams suitable for in-orbit beam–plasma experiments, while emphasizing scalability to a range of future space platforms.

Speaker: Mr Christopher Roper (Los Alamos National Laboratory, Georgia Institute of Technology)

14:00 SRF Cavity Detuning Characterization by Continuous Wavelet Transform: A Time-Frequency Analysis.

Sustainability is a key issue for both current and future particle accelerators. Superconducting RF cavities with high loaded quality factors play an important role in not only lowering the energy demands of particle accelerators but also the initial investment in RF amplifiers. But the narrow bandwidth associated with this high loaded quality, makes the need to minimize cavity detuning critical to maintain stable and efficient operation. In this context, characterization of microphonics detuning is essential, as it is a major error source, for implementation of effective mitigation schemes to reduce peak and rms RF power requirements.

Here we analyze SRF cavity detuning using the Continuous Wavelet Transform (CWT). Unlike conventional Fourier-based approaches, the CWT enables localized time-frequency decomposition, making it well-suited for identifying transient features that influence cavity behavior. Applying the CWT to measured detuning signals from a TESLA cavity at HoBiCaT testing facility at Helmholtz-Zentrum Berlin allows us to identify dominant detuning frequencies and track their evolution over time. The resulting time-frequency maps offer a more comprehensive understanding of the underlying mechanical environment and can support the development of more robust detuning mitigation and compensation strategies for SRF systems.

Speaker: Joyce Samantha Romero Jiménez (University of the Basque Country)

14:00 Static and Dynamic Field Characterisation of the Super Proton Synchrotron Bending Magnets

To ensure precise control of field quality in normal-conducting accelerator magnets, it is essential to develop models that accurately represent magnetic hysteresis during operational cycles. This study focuses on the dipole magnets of the CERN Super Proton Synchrotron (SPS) and investigates how variations in operational cycles produce different hysteresis and dynamic patterns in the integrated main magnetic and higher-order field multipoles. A combination of various magnetic field measurement systems was employed to evaluate the magnetic field quality, enabling direct observation of history dependence and reproducibility. Three regimes are identified: a history-dependent reversal curve along the ramp, eddy-current settling during end-of-ramp transients, and a rate-independent transfer function at the plateau. The analysis covers the integrated dipole and sextupole components, distinguishing rate-dependent eddy current effects from quasi-static hysteretic contributions. Two pre-cycle patterns currently used in operation are compared: a 200 GeV cycle and a 26 GeV cycle introduced in 2026 within the CERN Efficient Particle Accelerator (EPA) initiative. The aim is to provide a quantitative single-magnet assessment of this change of operation.

Speaker: Alberto Bellelli (European Organization for Nuclear Research, TU Wien)

14:00 Status of the Automated Activation of GaAs Photocathodes at Photo-CATCH*

Photocathodes based on the III-V seminconductor GaAs are used as photo-electron sources to supply spin-polarized electron beams for accelerator applications. In order to achieve a sufficient electron yield, a thin surface layer of cesium combined with an oxidant is applied onto the cathode surface in a process called the cathode activation. It is typically done manually by an experienced operator. This contribution presents the current status in the development and testing of an adaptive algorithm for automated activation at the Photo-CATCH test stand.

Speaker: Markus Engart (Technical University of Darmstadt)

14:00 Strain gauge implementation for a Nb_3 Sn superconducting multipole wiggler developed in KEK Photon Factory.

KEK Photon Factory is developing a Nb_3 Sn superconducting multipole wiggler (SC-MPW) for a next generation light source ring. The test coil unit has three round Nb_3 Sn coils and works as a three-pole wiggler. Nb_3 Sn superconductivity is strain sensitive, and training of resin impregnated Nb_3 Sn magnets could be limited by wire motion or cracks of the resin. Thus, it is important to monitor strain variation during cooling and excitation processes. Following the Unit 1 [1], we conducted an excitation test of the Unit 2 at the current density of 378 A/mm². In this test, one of the purposes is to validate a new strain measurement system that was first introduced into the Unit 2. Multiple strain gauges were attached to the magnet for monitoring strain variation. The strain measurement points were determined by ANSYS-FEM simulation. We also compared the simulation results with the measured values to assess our FEM model. In the future, we plan to conduct excitation tests at the target current density of 1000 A/mm², In the test, the strain-monitoring system will be implemented to the quench detection. We will report on the test results of the Unit 2 and progress of the next excitation test.
[1] C. Mitsuda, et al.: Proc. IPACʼ25, Taipei, Taiwan Aug.(2025) p.1851-1854

Speaker: Shota Nishi (The Graduate University for Advanced Studies, SOKENDAI)

14:00 Studies of longitudinal bunch-by-bunch feedback for SOLEIL II

In upgrading the present SOLEIL ring, it has been decided to introduce longitudinal bunch-by-bunch feedback (LFB) in addition to the already existing transverse feedback (TFB), because studies indicate that the new normal conducting fundamental RF cavities may excite longitudinal coupled-bunch instabilities (LCBI) due to their higher-order-modes (HOMs). SOLEIL II also plans to use bunch-lengthening harmonic cavities (HCs) to improve the Touschek lifetime, which may trigger complex LCBIs. The present study aims to develop an LFB system responsible for the longitudinal collective stability of the SOLEIL II beam. The theoretical calculation of the instability growth rate of the HOMs has been carried out, defining the preliminary performance requirements of the LFB. Among the three main parts of the system-detection, signal processing and kicking- the present work focuses on the development of the processing section and the paper also presents some design aspects of the kicker cavity along with a beam-based test converting the currently operating TFB system to LFB by utilizing the stripline as a longitudinal kicker.

Speaker: Elene Kravishvili (Université Paris-Saclay)

14:00 Studies of Transverse Emittance Growth of LHC-type Beams on the Long Injection Plateau of the CERN SPS

Transverse emittance growth was observed during the long injection plateau for high-intensity multi-bunch LHC-type beams in the CERN SPS, showing a clear dependence on the working point. Transverse tunes were increased to reduce emittance growth driven by integer resonances; however, a residual increase in emittance persists. To characterize this behavior and investigate its possible causes, transverse profile measurements were performed with the SPS wire scanners at several points along the injection plateau. These measurements are used to quantify the evolution of the transverse emittances and to assess the presence and possible generation of overpopulated tails.

Speaker: Ingrid Mases (European Organization for Nuclear Research)

14:00 Studies of unusual pickup geometries for the arc beam position monitors of the FCC-ee

The electron-positron Future Circular Collider (FCC-ee) has challenging requirements for beam instrumentation, including the need for thousands of high-resolution beam position monitors (BPMs) presenting low impedance to the circulating beam. This paper presents studies of different unusual pickup geometries including elliptical, asymmetric and retracted buttons. The impact of the different geometries on the simulated wake impedance and expected voltage signal of the pickups is explored and the potential benefits and disadvantages are described. These studies will inform the design of the FCC-ee arc BPM pickups.

Speaker: Emily Howling (John Adams Institute)

14:00 Studies on Optimization of a Tilted-Solenoid Muon Ionization Cooling Channel in G4beamline

We present optimization studies for a site-specific muon production and transport demonstrator for the Muon Collider planned at Fermilab. The design considers proton beams at 0.8, 8, and 120 GeV available from Fermilab accelerator facilities. The optimization work focuses on the performance of the target system and captures solenoid, a dedicated pion decay channel, a momentum selection chicane, and a beam transport section that prepares the muon beam for subsequent cooling experiments. Using G4Beamline as the primary simulation tool, we evaluate how magnetic optics, beam energy, target configuration, and channel geometry affect pion and muon yield and their phase space at the end of the transport line. Updated results and comparisons with reference designs will be shown, along with strategies to improve acceptance and deliver a high-quality beam for ionization cooling studies. The goal of the work is to deliver an optimized and realistic design for a future demonstrator at Fermilab.

Speaker: Cheng-Hsu Nee (University of Wisconsin–Madison)

14:00 Studies on the injection efficiency in the ESR

The ESR (Experimental Storage Ring) at GSI is one of the very few facilities that can offer highly charged heavy ion beams for precise atomic physics experiments. With each experiment during the beam time the requirements on the storage ring are changing and so the machine needs to be prepared every time from the beam injection to the extraction accordingly. In order to find the optimal setting for the injection it can practically mean to scan from scratch over several parameters, which can vary for different machine settings and therefore it can become time consuming.
We present in this proceeding a general analysis on the beam transmission at injection depending on the injection machine parameters and beam properties supported by simulations and tests. Based on this study, we propose a fast method to find the optimal parameter settings, especially in case of partially unknown properties.

Speaker: Areso Sherjan (GSI Helmholtz Centre for Heavy Ion Research)

14:00 STUDY AND TEST OF A TRIODE GUN FOR THE FLASH ELECTRON LINAC @ SAPIENZA

A 24-MeV prototype LINAC is under development at Sapienza University of Rome for FLASH radiobiological studies. The injector is a 12-keV triode thermionic electron gun from HeatWave Labs, providing grid-controlled current modulation for high current, low perveance, and short-pulse operation. To optimize its integration with the 24 MeV C-band hybrid standing and travelling wave structure, extensive particle tracking simulations of electron gun were performed using CST Particle Studio. Parametric scans of the anode voltage and grid potential were used to evaluate beam current, perveance, and emittance, identifying operating points that balance beam stability and charge for FLASH applications.
As the modern dispenser cathode requires stringent vacuum conditions below 1E-6 mbar, the LINAC was also modeled in Molflow+ to predict pressure profiles under realistic gas-load scenarios. Simulations revealed a potential vacuum limitation near the gun, leading to the design and implementation of an additional pumping port for better evacuation of gas molecules.
These results are benchmarked with initial experimental tests performed on an electron gun test bench at Sordina IORT Technologies and with Flash LINAC at the department of Basic and Applied Sciences for Engineering in Sapienza.
The combined simulation and experimental validation provides key requirements of an injector for a compact commercial LINACs for Flash applications.

Speaker: Shoaib Akbar (Sapienza University of Rome)

14:00 Study of Beam Dynamics in Magnetic Electron Buncher for Novosibirsk Free Electron Laser

Many applications of accelerator technology require electron bunches with length of up to 1 ps, the peak current exceeding 1 kA and the normalized emittance being less than 100 mm·mrad. To produce such bunches, special electron-optical systems ensuring beam bunching, known as magnetic bunchers, are widely used. Designing a 540° magnetic buncher has started several years ago at BINP [1]. Such a device enables users to obtain extremely short bunches with large charge. Effective bunching is ensured by the particularly strong dependence of the time of flight on the particle energy. In addition, for reduction of the maintenance costs, the whole electron-optical system is based on permanent magnets. This paper presents a brief review of the current state of the buncher design and the impact of space charge on transverse beam dynamics in electron optical elements of the device under construction.

Speaker: Shamil Lachynov (Budker Institute of Nuclear Physics)

14:00 Study of Electron Cloud in the FCC-ee Combined Function Magnets

The electron cloud effect is the main limiting factor in modem colliders. Therefore, this work studies the effects of electron cloud on charged particle beams in combined-function magnets for the FCC-ee collider using simulations in PyECLOUD and WARP to characterize the maximum secondary electron saturation levels and thus quantify the viability of the accelerator scheme. So on, compared the results in to determine if a 3-dimensional analysis, can provide additional information about the electron cloud effect in comparison to the classical 2 dimensional approach, thereby quantifying the cost-benefit of a model that is significantly more computationally expensive.

Speaker: Edgar Jair Villasenor Gonzalez (Universidad Autónoma de Sinaloa)

14:00 Study of gas scattering–induced beam losses and collimation for the SOLEIL II storage ring

The SOLEIL II storage ring will be equipped with many in-vacuum undulators (IVUs) and superbends, which are vulnerable to gas scattering–induced beam losses due to their small vertical gaps. In this paper, gas scattering–induced beam losses in SOLEIL II are studied with tracking simulations. The results show that, without vertical scrapers, 53$\%$ of elastic scattering–induced losses happen at IVUs with 4 mm vertical gaps, posing a risk of damage to their magnets over 15 years of operation. Detailed tracking finds that most of these losses originate from scattering events in short range, e.g., within half a turn. This suggests that one vertical scraper located upstream of each IVU group could provide optimal collimation, protecting the IVUs while maintaining the beam lifetime. However, this scheme is not allowed due to space constraints. A second optimal vertical collimation scheme is proposed with 2 scrapers, which reduces the beam losses at IVUs by 40$\%$ while maintaining an elastic scattering lifetime of 40 hours. In contrast to elastic scattering, inelastic scattering leads to only minor beam losses and remains acceptable.

Speaker: Yuejing Huang (University of Science and Technology of China)

14:00 Study on energy stability of high-charge bunches from laser plasma accelerators for ring injectors

Laser plasma accelerators (LPA) are expected to achieve acceleration gradients several orders of magnitude higher than conventional accelerators, thereby providing a promising route to the development of compact high-energy particle accelerators. However, the electron beams generated by current LPAs exhibit considerable energy spread and significant shot-to-shot energy jitter—issues that are particularly pronounced for high-charge bunches—severely restricting their practical application in fields such as ring injectors.
Our team proposed a transfer line configuration integrating an active plasma dechirper, a passive plasma dechirper, and magnetic chicanes (Xueyan Shi et al. New J. Phys. 26, 073045, 2024). Start-to-end simulations demonstrated that for 500 MeV electron beams with a charge of 500 pC, this scheme reduces the energy jitter from ±2% to 0.1% and the energy spread from 1.2% to 0.5%.
In the present work, we extend the beam charge to the nanocoulomb (nC) level to explore the performance limits of this approach. Preliminary simulation results show that for a 1 nC electron beam with an initial root-mean-square (rms) energy spread of 1.2% and energy jitter of ±2%, the proposed scheme can reduce these parameters to 0.2% and 0.4%, respectively, while maintaining a transmission efficiency of 81.2%. Additionally, we verified the feasibility of using such LPA-generated beams as injectors for the High Energy Photon Source (HEPS) booster by simulations.

Speaker: YiQun Shi (Institute of High Energy Physics)

14:00 Study on polarization control of planar undulator system based on magnetic field modulation

The fast polarization switching of undulator radiation has attracted more and more attention in recent years. Recently, a new method has been proposed for fast polarization switching up to kilohertz of undulator radiation by using magnetic field modulation generated from low-current electromagnetic coils. Through fast switching the power of coils, the radiation spectra of two undulators can be rapidly shifted into and out of the bandpass of a monochromator, enabling fast polarization switching for the user beamline. In this paper, we have studied the performance of the scheme using planar undulators. The performance of related parameters, such as photon flux, polarization degree, and spot distribution, will be reported.

Speaker: NanRui Yang (University of Science and Technology of China)

14:00 Study on the vacuum properties of Pd/Ti bilayer thin films

Non-evaporable getter (NEG) thin films are essential for achieving ultra-high vacuum in the narrow-bore chambers. Pd/Ti bilayer NEG thin films were deposited on oxygen-free copper and silicon substrates by DC magnetron sputtering. The microstructure and elemental distribution were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The films exhibit a cauliflower-like surface morphology and a columnar cross-sectional structure, providing a high specific surface area and effective pathways for gas diffusion. The pumping speed for H$_2$ was evaluated using the constant-pressure dynamic flow method after activation at 150 °C for 12 h. The pumping speed decreases from 0.13 to 0.02 L s$^{-1}$ within a pumped quantity range of $1 \times 10^{-5}$ - $6.5 \times 10^{-3}$ Pa L. A non-monotonic variation in pumping speed was observed, which is attributed to hydrogen adsorption, dissociation on the Pd surface, and subsequent diffusion into the Ti layer for hydride formation. The results demonstrate that the Pd overlayer effectively enables low-temperature activation and enhances hydrogen sorption behavior, indicating that Pd/Ti NEG thin films are promising candidates for ultra-high vacuum applications in accelerator systems.

Speaker: Tao Guo (University of Science and Technology of China)

14:00 Studying Coherent Transition Radiation Spatial Image Features for Bunch Length Diagnostics

Coherent transition radiation (CTR) has been widely used for developing diagnostics of particle beams due to its broadband spectrum, which provides information on the particle distribution, and its relatively simple experimental setup compared to other sources of coherent radiation. For short and ultrashort electron bunches, ps- to fs-long, methods such as CTR spectrometry and interferometry have been used. Recently, an alternative method using point-to-point spatial imaging of the transition radiation source plane has been studied, showing promising results in which image features, such as the image width, can be tied to the bunch length. However, a more in-depth image analysis is required. In this work, an attempt is made to model some of the bunch profile features from the CTR spatial images using conventional image and data analysis techniques. The CTR spatial images are simulated in Ansys Zemax OpticStudio for a broad range of bunch profiles, from single-Gaussian to multi-Gaussian distributions that emulate more realistic bunches. The results form the basis for the next stage of analysis of experimental CTR images for retrieving the longitudinal bunch profile.

Speaker: Ana Guisao-Betancur (University of Liverpool, Cockcroft Institute)

14:00 Sub-10 fs synchronization in laser-plasma accelerators with terahertz frequency bunch manipulation

There is a growing demand for generating and transporting very short femtosecond-scale, high-charge-density relativistic electron bunches [1-2]*. Applications range from extreme light sources such as free-electron lasers to future linear colliders. Laser-plasma wakefield accelerators (LWFA) [3] offer a promising approach for compact high-gradient acceleration, but electrons generated directly from the plasma in a non-linear self-injection process show poor stability and limited control. External injection [4-5] provides a solution but requires extremely short electron bunches with precise control, which is currently limited by compression and timing jitter in conventional radio-frequency accelerators [6].
We show that laser-driven terahertz (THz) control of electron bunches can enable phase-locked, laser-synchronized compression with suppressed time jitter [7]. Using computational methods, we explore the external injection of such THz-controlled electron bunches into a LWFA. By utilizing intrinsic synchronization and THz-driven energy manipulation, we demonstrate significant stabilization in external injection while preserving high bunch quality.

Speaker: Mr Aras Amini (University of Manchester, Cockcroft Institute)

14:00 Sub-5-fs compression and synchronization of relativistic electron bunches for high-performance MeV UED at the upgraded FORTRESS beamline

The generation of high-brightness electron beams with ultrashort duration and high temporal stability is essential for ultrafast electron diffraction (UED), which has become a powerful tool for ultrafast structural dynamics studies with high spatiotemporal resolution. However, simultaneously achieving sub-10 fs bunch duration and synchronization with pump laser remains challenging in practice. Here we report an upgrade of the FORTRESS (Facility Of Relativistic Time-Resolved Electron Sources and Scattering) beamline at Tsinghua University. By utilizing an α-magnet-based scheme and a 1.4-cell S-band photocathode gun, with optimized control of the time-of-flight (TOF)-momentum correlation and the time-momentum correlation in longitudinal phase space mainly governed by the initial chirp, a bunch duration of 3.47 fs with 4.34 fs TOF jitter characterized by THz streaking has been achieved, corresponding to a temporal precision of ~5 fs. The beamline layout, beam dynamics simulation, diagnostic methods and pump-probe UED experiments with high-performance results will be discussed.

Speaker: Zhiyuan Wang (Tsinghua University)

14:00 Superblock-based SCILAB–Xcos simulation of electron radiation intensity for multiple undulator schemes

Abstract: A SCILAB Xcos model has been redesigned using Super Blocks to simulate electron trajectories in different undulator schemes. The use of Super Blocks simplifies the model structure, reduces configuration complexity, and enhances modularity for further extension. This improvement allows easy modification of parameters and undulator configurations without rebuilding the complete model. The study is further extended to calculate radiation intensity and analyse spectral characteristics at various electron beam energies. Comparison of spectra software demonstrates the accuracy and reliability of the developed Super Block–based Xcos model for studying undulator radiation and free-electron laser characteristics.

Speaker: Ms Mahazbeen Sayed (Rajiv Gandhi Technical University)

14:00 SuperKEKB Beam Transport Tracking and Dynamic Aperture Comparison as an approximation for injection efficiency

A new Energy Compression System (ECS), consisting of four RF cavities, was installed in the SuperKEKB electron transfer line (BTe) during the 2025 summer shutdown. Optimising BTe performance using full multi-turn injection simulations is computationally demanding. To accelerate this process, we compare the beam tracked through BTe — including the ECS — to the dynamic aperture of the High-Energy Ring lattice obtained from Xsuite simulations. The SAD lattices were converted to Xsuite and benchmarked to ensure consistency between the two frameworks. This method provides a fast, first-order estimate of the expected injection efficiency by optimising the survival fraction through the evaluation of particle action amplitudes, while also accounting for physical apertures. Radiation effects and a tapering can be optionally included. Different injection schemes are supported within the same framework. Together, these elements enable rapid optimisation of the ECS parameters with significantly reduced computational cost.

Speaker: Nikita van Gils (European Organization for Nuclear Research)

14:00 Superposition of Multipolar Transverse Electric Modes in a Unified RF Structure

A field-driven method is presented for synthesising multipolar transverse-electric cavities. Cylindrical standing-wave TE solutions are superimposed analytically, and the cavity surface is reconstructed by enforcing perfect-electric-conductor boundary conditions. The method produces closed hybrid cavity geometries whose modal content is validated against CST eigenmode simulations. Two examples are shown: TE$_{\{0,2\}1}$ and TE$_{\{2,4\}1}$ hybrid cavities. In both cases, the intended azimuthal field structure is preserved with sub-percent-level agreement between the analytic model and CST. The method provides a route to structured TE-mode RF cavities for future beam-manipulation studies.

Speaker: Oliver Betteridge (Cockcroft Institute)

14:00 Superradiant Terahertz Radiation Generation at EuXFEL: integration, commissioning, and initial measurements

The Superradiant Terahertz Radiation Generation (STERN) experimental chamber has recently been successfully integrated into the EuXFEL electron beam line. The setup incorporates Cherenkov wakefield structures and a diffraction radiation sheet to generate superradiant Terahertz (THz) pulses as the electron beam passes through. In future operation, these pulses are planned to be delivered to the EuXFEL user hutches to be used in pump-probe experiments.
This work describes the main challenges encountered during the chamber installation and the commissioning phase of the experiment. It also reports on the commissioning of a new mini-beta lattice providing a strongly focused beam at the experimental location. Finally, first measurement results of the THz generation and transport are presented based on availability, together with a comparison to corresponding simulation predictions.

Speaker: Karel Peetermans (Deutsches Elektronen-Synchrotron DESY)

14:00 SymCSR: Tracking 6D phase space dynamics of electron beam with coherent synchrotron radiation

Coherent synchrotron radiation (CSR) is a critical effect in the design and operation of high-brightness electron accelerators, as it can lead to significant energy loss and emittance growth. In this paper, we present SymCSR, a first-principle tracking program for simulating the 6D phase space dynamics of electron beams under the influence of CSR. SymCSR computes the radiation reaction field of electrons based on its retarded and instantaneous trajectory, which efficiently reduces the requirement on macroparticle numbers. The dynamics of electron beam in various dimensions are calculated using SymCSR and are compared with theoretical models.

Speaker: Zhuoyuan Liu (Tsinghua University)

14:00 Symplectic integrator for insertion devices tracking at SIRIUS

This paper presents the development of a symplectic integrator for particle tracking in insertion devices at SIRIUS. The method relies on analytical field representations specifically tailored to model the magnetic structure of the device accurately. Tracking results obtained with the new integrator are compared with those from traditional kickmaps, and the differences observed in dynamical aperture calculations and frequency map analyses are examined, showing the integrator’s effect on long-term beam dynamics predictions. The integrator is further applied to specify the field roll-off requirements for SIRIUS’s first CPMU, which will operate with a minimum gap of 4.65 mm at a high-beta section.

Speaker: Gabriel Ascenção (Brazilian Synchrotron Light Laboratory)

14:00 TDC-Based Phase Measurement for the Radio Frequency System of a Synchrotron Radiation Accelerator

Maintaining a constant phase difference between the reference (Ref) and cavity voltage sampling (Pt) signals is critical for stable operation of the Hefei Light Source (HLS) storage ring's RF system. This requires high-precision real-time phase detection capable of identifying lead or lag, to quickly restore the preset phase after startup or recovery, and to maintain the relationship between the beam synchronous phase in the low-level RF (LLRF) loop and the bunch-by-bunch feedback system. Conventional phase detection methods, based on either phase detector chips or the CORDIC algorithm, face inherent drawbacks. The former has limited accuracy (> ±2°) and needs extra circuitry to determine phase lead/lag, increasing design complexity. The latter requires a high-speed data acquisition system and dedicated processing algorithms, significantly increasing system complexity and cost. To overcome these limitations, this paper proposes a novel phase detection scheme using a Time-to-Digital Converter (TDC) implemented in a Field-Programmable Gate Array (FPGA). The design employs multi-phase TDC and averaging techniques, enabling fast and accurate measurements immune to transmission line delays. The system achieves a phase resolution of 0.359°, requires only one-time calibration, and reliably meets long-term online phase detection needs for the HLS.

Speaker: xiao qu (University of Science and Technology of China)

14:00 The Compton Backscattering Source COBRA at the S-DALINAC

The COBRA source (Compton Backscattering at a Recirculating Accelerator) utilizes a 100 W Yb:YAG laser that is synchronized with the electron beam of the superconducting Darmstadt linear accelerator S-DALINAC * for head-on collisions. The backscattered photons in the X-ray energy range can be collimated into a quasi-monochromatic beam for electron beam diagnostics and as a technology demonstrator. The first collision of the electron and laser beam is planned in an upcoming beamtime with multi-turn recirculation. During operation, COBRA utilizes stabilization systems for both beams. Later, COBRA is foreseen to be operated during energy-recovery mode **, serving as a demonstrator for future Compton scattering light sources. This contribution provides an overview of the COBRA source, highlighting recent upgrades to the detector setup and developments of the laser beamline.

Speaker: Ms Lisa Beate Dingeldein (Technical University of Darmstadt)

14:00 The essence factor to deteriorate the circular polarization radiation performance in APPLE-KNOT undulator

The APPLE-KNOT undulator forms composite magnetic fields by superimposing APPLE and KNOT fields with different period lengths. In this configuration, in which the APPLE field serves as the dominant component to approximate the target photon energy, while the KNOT field acts as an additional component to transversely deflect the electron beam off-axis. Although variable polarization modes can be realized with a low on-axis heat load, previous studies have observed a sharp reduction in flux and significant degradation of the polarization degree in the circular polarization (CP) mode. This paper discusses this phenomenon in detail from a theoretical perspective. The analysis reveals that the presence of an additional field with a longer period is the essence factor that inherently suppresses the radiation performance of CP mode. Theoretical findings are highly consistent with simulation results, demonstrating that selecting the KNOT field as the dominant component can effectively improve CP characteristics without significantly compromising the linear polarization performance.

Speaker: Binghao Zhang (University of Science and Technology of China)

14:00 The impact of transverse-longitudinal coupling on longitudinal microwave instability

In a storage ring with an extremely small global phase slippage, the bunch length can vary significantly within one turn due to the partial phase slippage and transverse-longitudinal coupling, which means the adiabatic approximation usually adopted for longitudinal dynamics breaks down. The impact of such a bunch length variation and exchange of the head and tail part of the beam arising from the partial phase slippage on the coherent synchrotron radiation (CSR) induced longitudinal microwave instability (MWI) threshold has recently been theoretically investigated by some of the authors*. In this work, we have extended the study to consider the influence of transverse-longitudinal coupling.

Speaker: Jihong Bian (Tsinghua University)

14:00 Tomographic reconstruction of longitudinal phase space from FCT measurements

For the analysis of longitudinal dynamics in synchrotrons and storage rings, the reconstruction of the beam distribution in longitudinal phase space is of high interest. This study applies a tomographic method to longitudinal beam profiles measured in the ESR to reconstruct longitudinal phase space. We show the limitations of these methods for the nonlinear beam dynamics in an RF bucket.

Speaker: Julian Rausch (Goethe University Frankfurt)

14:00 Towards Online-Tunable XFELs: Programmable Laser Shaping to Streaming End-Station Diagnostics

LCLS-II introduces MHz-rate operation and sub-femtosecond X-ray pulses, creating a need for high-rate control mechanisms at the photoinjector and diagnostic systems capable of extracting pulse structure on every shot. This work presents two key components toward meeting these requirements. First, a programmable photoinjector-laser system combining a spatial light modulator with dispersion-controlled nonlinear synthesis enables tunable UV temporal profiles compatible with the LCLS-II photocathode. Beamtime measurements demonstrate controllable modulation of the electron bunch and corresponding structure in the emitted X-ray pulses, including a triple-hump temporal pattern. Second, a high-throughput streaming front-end and machine-learning framework is developed for the Multi-Resolution Cookiebox diagnostic to rapidly extract attosecond X-ray pulse structure at high repetition rate. Together, these advances supply essential building blocks for future adaptive operation, including multiplexed experimental modes, live tuning of X-ray output, and integration with emerging modeling and optimization efforts.**

Speaker: Jack Hirschman (Stanford University, SLAC National Accelerator Laboratory)

14:00 Transfer Learning for Generalizing a Hybrid Autoencoder-Isolation Forest Model for Time Series Anomaly Detection in ARRONAX Cyclotron Operational Data

In the context of the operational monitoring of the ARRONAX C70XP cyclotron, our previous work addressed the limitations of the Isolation Forest (IF) algorithm in detecting local anomalies, particularly those occurring near the mean of normal data, due to its reliance on axis-parallel splits. To overcome this issue, we developed and validated a hybrid model combining an autoencoder and IF, using time series data from the proton beam intensity on target. This approach significantly improved the detection of both global and local anomalies, with no false alarms observed during evaluation. Building on these results, the present study investigates the use of transfer learning to generalize the hybrid model to other process variables originating from different subsystems, including the source, injector, and cyclotron core. Results suggest that the model can effectively label large volumes of multivariate operational data, supporting the development of a more scalable and integrated anomaly detection framework for the C70XP.

Speaker: Fatima Basbous (GIP ARRONAX, Nantes Université)

14:00 Tune Compensation for Insertion Devices Motion at the SOLARIS Storage Ring

Precise control of betatron tune is essential for maintaining beam stability in modern synchrotron light sources. At the SOLARIS storage ring, tune perturbations induced by undulator gap and phase present a significant operational challenge. This study presents a method for local tune compensation during the gap and phase motion of Apple II type undulator, installed upstream of a dedicated beamline. The approach employs a tune-feedback system based on two local quadrupoles and two global magnet families driven by a feed-forward table generated from a systematic scan of the undulator parameters (gap, phase) and the corresponding tune shifts. Prior to table generation, the magnets' response matrices for both tune planes were independently obtained. The proposed method ensures effective and reproducible mitigation of tune perturbations during undulator motion, enabling stable machine performance and improved beam quality at SOLARIS.

Speaker: Maria Ünal (SOLARIS National Synchrotron Radiation Centre)

14:00 Understanding energy-induced optics distortions in the LHC

Small momentum offsets in the LHC can generate significant optics distortions, particularly at low $\beta$*. The beam energy carries a relative uncertainty of approximately $10^{-3}$, which is insufficient for precise optics control. To better understand the impact of energy on the optics, two beam-based techniques have been explored. The first applies a global linear response matrix between BPM phase advances and $\Delta p/p$; while effective in simulation, this method is sensitive and does not reproduce the response observed in the machine. We introduce a new approach based on the principle of Deep Lie Map Networks (DLMN), which fits turn-by-turn BPM trajectories to a differentiable tracking model. Using the single-pass forward differentiation capability of MAD-NG, derivatives of the orbit with respect to $\Delta p/p$ are computed directly within the symplectic tracking engine. The results reveal arc-by-arc variations consistent with dipole-induced orbit distortions, providing insight into orbit behaviour around the ring. The measured response also agrees with that observed in the machine, demonstrating that the DLMN offers a promising new method for analysing the effect of energy on the optics of the LHC.

Speaker: Joshua Gray (European Organization for Nuclear Research)

14:00 Understanding the connections between grain growth and flux expulsion in low RRR niobium SRF cavities

The SRF community has shown that high temperature annealing can improve the flux expulsion of niobium cavities during cooldown. The required temperature will vary between cavities and different batches of material, typically around 800 C and up to 1000 C. However, for niobium with a low residual resistance ratio (RRR), even 1000 C is not enough to improve its poor flux expulsion. The purpose of this study is to observe the grain growth behavior of low RRR niobium coupons subjected to high temperature annealing to identify the mechanism for improving flux expulsion in low RRR cavities. We anneal the low RRR material up to 1200 C to understand the limits of flux expulsion performance. We observe that low RRR material experiences less grain growth than high RRR when annealed at the same temperature. We search for the limitations to grain growth in low RRR material and develop a diagnostic based on grain structure to determine the appropriate recipe for good flux expulsion. The results of this study have the potential to unlock a new understanding on SRF materials and enable the next generation of high Q/high gradient surface treatments.

Speaker: Katrina Howard (University of Chicago)

14:00 Use of DBSCAN for full-automatic-data-based anomaly detection method on Turn-by-Turn Beam Position Monitors (TbTBPMs) in SuperKEKB

In order to consistently operate collider at peak luminosity, one have to know in detail the full magnetic lattice of the colliding rings, and to know in particular the deviation of the real lattice from the model used in the design phase.
Turn-by-turn BPMs surveys are one of the method available to measure this deviation. Based on the n-BPM method developped at CERN, the spectral response of the TbTBPMs all around the rings allow for the reconstruction of the full effective magnetic lattice.
However, the measurement is very dependant on the status and precision of each TbTBPM in the ring.
A method to automatically detect and eliminate problematic BPMs from magnetic lattice reconstruction scripts is presented. It is based on a library called Time2Feat to extract and select automatically the most dissociative features from the TbTBPMs time-measurements, and the Density Based Spectral Clustering Application with Noise (DBSCAN) algorithm to detect potential outliers from a clustering of the BPMs inside the hyperspace of the computed features.
The main asset of this method is its light weight since very little training is needed, the possibility to detect outliers from very scarse measurements as input (the very problematic BPMs are detected with only one measurement from each BPM), and a data-based selection of features, preventing the introduction of any bias and allowing for the best feature-set selection possible for each measurement.

Speaker: Quentin Bruant (Commissariat à l'Énergie Atomique et aux Énergies Alternatives)

14:00 Using Machine Learning in Control System for Isochronous Cyclotron

Crocker Nuclear Laboratory has been going through a modernization in its control system. One of the projects being made for the modernization is using machine learning to model the isochronous cyclotron environment & to use that model for autonomous control. The model uses convoluted neural networks, and uses 32 controlled parameters that all affect the beam current and stability. This model is then used in a reinforcement learning model that will be used for autonomous control, which serves as a piece on the new digital control system that is currently being implemented. The system will focus on controlling the trim coil magnets to maintain a stable beam. The goal is to unravel new/simple tunings for a continuous spectrum of energies of the machine.

Speaker: Gabriel Soto (University of California, Davis)

14:00 X Band Linac Machine Design for Very High Energy Electron Therapy

Very high energy electrons (VHEE) are a potential future modality in the field of radiotherapy. They have garnered considerable interest because they possess a unique combination of several properties including: being capable of deep tissue penetration (>30 cm), relative insensitivity to tissue inhomogeneities and being well suited to FLASH therapy. FLASH is the use of ultra-high dose rates which have been shown to reduce cell death in healthy tissue whilst maintaining toxicity to tumours. Recent studies indicate that higher energy beams produce less scattering and more precise dose delivery up to at least 250 MeV. This paper provides a design for a 250 MeV linac with dose rates exceeding 100 Gy/s in a 10 cm × 10 cm wide field size. The design is centred on a bi-periodic, π/2 mode, normal conducting, standing wave, accelerating cavity which emphasises stability. A gradient of 100 MV/m has been chosen to achieve the compactness potentially required to fit the accelerator in a hospital setting. To this end, 11.9942 GHz X-band technology has been selected which, along with extensive cell geometry optimisation, has produced a shunt impedance of > 95 MΩ/m and whilst minimising surface electric and magnetic fields.

Speaker: Euan Smith (University of Manchester, Cockcroft Institute)

14:00 X-ray frequency combs generation using echoenabled harmonic generation free electron laser

Optical frequency comb (OFC) technology provides precise measurement tools for optical frequencies, leading to revolutionary changes in the field of optics.OFCs consist of a series of uniformly spaced spectral lines resembling the teeth of a comb, and they have found widespread applications in timing, precision spectroscopy, and fundamental physics.Extending this technology into the EUV to X-raydomaintoachieve ultra-high precision detection of molecular and atomic structures has been a significant challenge faced by the scientific community.The next generation of light sources—free electron lasers—holds promise for addressing this challenge.By positioning different groups of undulators at various harmonic resonances within the EEHG-FEL, periodic modulation of the electron beam will be formed, which, with the appropriate parameter settings, will enable the generation of fully coherent optical frequency combs

Speaker: Lanpeng Ni (Shanghai Institute of Applied Physics)

14:00 Zeptosecond γ-Ray Pulses Generation via FEL-Driven Microbunching and Laser-Compton Scattering

The ultrashort pulse concept, known as "measurement-before-destruction," pioneers ultrafast probing of sensitive states by allowing signal capture before significant laser-induced changes occur. While Free-Electron Lasers (FELs) drive progress in attosecond X-ray generation for electron dynamics, the next frontier—time-resolved nuclear dynamics—demands sub-attosecond to zeptosecond pulses at MeV energies, a regime where standalone FELs face fundamental resource and physical limitations.
To overcome these barriers, we propose a novel methodology combining FEL technology with laser Compton scattering to generate ultrashort (hundreds of zeptoseconds) pulses with extremely high photon energies (MeV to hundreds of MeV). This approach effectively leverages Compton scattering to produce high-quality gamma rays while bypassing the pulse broadening caused by FEL slippage. This innovation offers the potential to investigate previously inaccessible level densities in compound nuclei and nuclei far from stability, and to advance studies in fundamental quantum measurement phenomena such as the Quantum Zeno and Anti-Zeno Effects, opening new possibilities beyond nuclear physics.

Speaker: jinke Xiong (Shanghai Institute of Applied Physics, Chinese Academy of Sciences)

18:00 → 20:00 Welcome

Monday 18 May

09:00 → 09:40 MC0 : opening session: Welcome Address

09:00 Chair's Opening Welcome for IPAC'26

Speaker: Peter McIntosh (Science and Technology Facilities Council)

09:05 Welcome Address

Speaker: Stefano Panebianco (Ministère de l’Enseignement Supérieur et de la Recherche)

09:15 Welcome Address

Speaker: Jean Daillant (European Synchrotron Radiation Facility)

09:20 Welcome Address

Speaker: Jean SUSINI (Synchrotron soleil)

09:25 Welcome Address

Speaker: Pierre Vedrine (Commissariat à l'Énergie Atomique et aux Énergies Alternatives)

09:30 Welcome Address

Speaker: Hervé Savajols (Grand Accélérateur National d'Ions Lourds)

09:35 LOC Chair Welcome, IPAC'26 Practical Information

Speaker: Dr Hanna Franberg Delahaye (Grand Accélérateur National d'Ions Lourds)

09:40 → 10:40 MC0 : opening session

09:40 GANIL-SPIRAL2 facility - Recent achievements and upgrades

The Grand Accélérateur National d'Ions Lourds (GANIL) is a multi-beam facility, unique in intensity, particle types and simultaneous production. The Sys-tème de Production d’Ions Radioactifs en Ligne de 2ème génération (SPIRAL2) facility covering an excep-tionally broad intensity range, from nanoamperes to milliamperes further enhances the scientific opportu-nities of the laboratory. The first proton beams from the LINAC were produced in 2019 and is operational for physics experiments since 2022. The cyclotron operation and the initial operational challenges and lessons learned in the first years of operation of the LINAC and Neutrons For Science (NFS) facilities are presented. The physics program at GANIL-SPIRAL2 is briefly presented. The ongoing upgrades and devel-opments essential to sustain increasingly ambitious pure and applied science programs are also presented.

Speaker: Robin Ferdinand (Grand Accélérateur National d'Ions Lourds, Commissariat à l'Energie Atomique)

MOI4M01_edited_version.pdf

10:10 CERN’s future vision and priorities

The Update for the European Strategy for Particle Physics will take place over 2025, with various community inputs and an open symposium. Many are eagerly awaiting the outcome and what it means for CERN and large collider projects worldwide. If the response from the ESPP is clear and decisive, then this talk will be an opportunity to elaborate CERN's plans with the international accelerator community. If the ESPP does not offer a clear direction, then this would be an opportunity to hear from CERN's new Director General about CERN's plan going forward.

Speaker: Mark Thomson (University of Cambridge)

MOI1M01_talk.pdf

MOI1M01_talk.pdf

MOI1M01_talk.pptx

10:40 → 11:10 Coffee break

11:10 → 12:40 MC0 : opening session

11:10 Synchrotron light facility updates: the bright future of synchrotron science

Synchrotron light sources are undergoing a major transformation, driven by the need for higher brilliance, greater efficiency, and more advanced experimental capabilities. The transition to 4th generation synchrotrons is enabling groundbreaking research in imaging, spectroscopy, and materials science, with improvements in accelerator design, beam stability, and data handling. Key advancements include multi-bend achromat lattices for reduced emittance, energy-efficient permanent magnet systems, and increasingly automated, AI-enhanced workflows for data acquisition and analysis. Facilities worldwide are also integrating new beamline technologies to support high-throughput experiments and multimodal studies. In parallel, efforts to improve sustainability and optimize user access models are shaping the future of synchrotron research. These developments are not only expanding scientific possibilities but also reinforcing international collaboration, ensuring synchrotron facilities remain at the forefront of innovation.

Speaker: Laurent Chapon (Advanced Photon Source)

IPAC-2026-Chapon-Synchrotron_talk.pdf

IPAC-2026-Chapon-Synchrotron_talk.pptx

MOI2M01_talk_edited_version.pdf

11:40 First acceleration of positive muons: from initial demonstration to high-energy development

The realization of low-emittance muon beams through cooling and acceleration is a pivotal technology with significant potential to advance various scientific disciplines, ranging from fundamental particle physics to applied material science. Recently, we successfully demonstrated, for the first time, the acceleration of positive muons generated by resonant multi-photon ionization of muonium using a radio-frequency quadrupole linac (RFQ), accelerating them from thermal energy to 100 keV. To further advance these studies, a dedicated muon linac, composed of four types of RF cavities, has been developed to accelerate muons to 212 MeV, approaching the speed of light. The beamline and accelerator are being constructed from the upstream, and the acceleration up to the second RF accelerator is already planned, with further acceleration up to a few MeV scheduled from 2026 fiscal years. This presentation shows the results of the first acceleration of positive muons and ongoing developments aimed at achieving higher energies.

Speaker: Masashi Otani (High Energy Accelerator Research Organization, Japan Proton Accelerator Research Complex)

MOI4M02_talk_edited_version.pdf

12:10 Commissioning progress of the ESS linear accelerator

The European Spallation Source (ESS) is in the final stages of commissioning its linear accelerator (linac), which will deliver a high-power proton beam for neutron production. The commissioning process involves progressive testing of subsystems, including the ion source, radio-frequency quadrupole (RFQ), and superconducting cavities, to ensure stable and reliable beam operation. Key challenges include beam dynamics optimization, machine protection, and high-power RF system integration. Within this presentation an overview of the commissioning status, key milestones achieved, and expectations for the first beam on target, marking a significant step toward full facility operation could be given.

Speaker: Natalia Milas (European Spallation Source)

MOI4M03_edited_version.pdf

MOI4M03_talk.pdf

MOI4M03_talk.pptx

12:40 → 14:00 Lunch break

14:00 → 16:00 MC1 : Colliders and Related Accelerators

14:00 Project status and R&D efforts for Super Tau-Charm Facility

The Super Tau-Charm Facility (STCF) was proposed as a third-generation circular electron-positron collider in the energy range of 2-7 GeV (CoM) and with a luminosity greater than 5*10^34 cm^-2s^-1 @4 GeV, aiming to explore charm physics and tau physics in the next decades. This presentation will introduce the facility design and R&D efforts for STCF, including the design goal, accelerator and detector schemes, and key technological R&D efforts, with focus on the accelerator. Under the financial support of the key technology R&D project by the local governments and other national funding agencies, the STCF accelerator team including international collaborators has completed the conceptual design of the accelerator, and started the technical design. The accelerator consists of a full-energy injector consisting of multi-section linacs and a positron accumulator ring and a double-ring collider with the crab-waist collision scheme. Key physics and technological challenges will be addressed. Ongoing R&D efforts and progresses will be summarized. The project planning will also be given. International collaboration is much welcome.

Speaker: Jingyu Tang (University of Science and Technology of China)

MOI1T01.docx

MOI1T01_edited_version.pdf

MOI1T01.pdf

14:30 Linear collider studies and prospects

Linear e⁺e- colliders can provide a broad physics programme spanning centre-of-mass energies from the Z pole to the TeV scale, enabling precision measurements of the Higgs boson, top quark, and the electroweak sector with polarised beams. Two mature accelerator technologies are under development for a possible linear collider facility (LCF) at CERN beyond the HL-LHC: the superconducting RF (SCRF) approach embodied by the ILC as developed for hosting in Japan, and the proposed normal-conducting high gradient RF (NCRF) two-beam scheme of CLIC. Both options are described in detailed documents contributed to the European Strategy for Particle Physics Update (ESPPU) process. Beyond an initial implementation in the 250-380 GeV range, upgrades in energy and/or luminosity enabled by R&D on cool copper structures, higher gradient SCRF, energy recovery and plasma wakefield options can be considered. This paper summarises the status of the studies and associated technology developments, potential long-term upgrade paths, and key implementation parameters including cost, power, and sustainability assessments.

Speaker: Steinar Stapnes (European Organization for Nuclear Research)

MOI1T02_edited_version.pdf

MOI1T02_talk_edited_version.pdf

15:00 Obtaining a record luminosity production in the Large Hadron Collider in 2025

The Large Hadron Collider (LHC) run in 2025 was the last long production year of LHC Run 3 (2022 to 2026). To mitigate potential radiation damage to magnets installed in the low-beta sections due to the integrated radiation dose near the high luminosity experiments, a flat optics was used for the first time in beam operation, underlining the adaptability of the LHC. A record production of 125 fb$^{-1}$ was achieved in 2025 despite vacuum component non-conformities leading to intensity limitations in one of the beams during part of the year. The integrated luminosity collected by each of the two high luminosity experiments since the startup of the LHC now exceeds 500 fb$^{-1}$. This paper presents the configuration, operational strategies and beam parameters of the LHC in 2025 which led to another record year.

Speaker: Jorg Wenninger (European Organization for Nuclear Research)

MOO1T01_edited_version.pdf

MOO1T01_talk.pdf

MOO1T01_talk.pptx

15:20 Progress towards a muon collider

The muon collider concept promises a unique opportunity to push the energy frontier in particle physics. The large muon mass suppresses synchrotron radiation and allows the acceleration and collision of the beams in rings and the use of technology more similar to hadron colliders. Muons are point-like, in contrast to protons, and thus can achieve a similar physics reach with less energy, allowing for a more compact machine. However muons have a lifetime of only 2.2 microseconds at rest. The muon beam thus needs to be cooled and accelerated rapidly to maximise the luminosity, which creates several technology challenges. The International Muon Collider Collaboration is implementing an intense R&D programme to address these challenges and to develop the concept maturity. The presentation will highlight the key challenges, summarise the progress of the work and the proposed R&D plan for the next decade.

Speaker: Paul Jurj (Imperial College London)

MOO1T03_edited_version.pdf

MOO1T03_talk_edited_version.pdf

15:40 The Ghost Collider: an innovative Higgs Factory

The Ghost Collider is a proposal for a 550 GeV center-of-mass (275 GeV per beam) linear collider with four interaction regions, each with the design luminosity. The primary innovation is the use of “ghost bunches” containing equal numbers of electrons and positrons, therefore being electrically neutral. In the linacs, energy is transferred between electrons and positrons in the same bunch, decelerating one type of particle and using the energy to accelerate the other; a new class of Energy Recovery Linac. At the interaction points (IPs), collisions between two neutral ghost bunches occur. Historically this approach has been referred to as "charge compensation of beam-beam". To avoid instabilities, round beams with small disruption parameter are arranged at the IPs, ensuring particles and their energy can be recycled with minimal loss. Four “serial IPs” are incorporated, where chromatic errors produced in one IP are canceled in the following IP. All interaction points have the nominal luminosity per IP of $2.8 \times 10^{34}$ cm$^{-2}$ s$^{-1}$ for a facility luminosity of $11 \times 10^{34}$ cm$^{-2}$ s$^{-1}$ @ 100 MW total electrical power for SR replacement, linac RF, cryogenic and damping ring systems. The result is a totally original concept for an electron-positron collider.

Speaker: Robert Apsimon (Lancaster University, Cockcroft Institute)

MOO1T02_edited_version.pdf

MOO1T02_talk.pdf

MOO1T02_talk.pdf

MOO1T02_talk.pptx

14:00 → 16:00 MC7: Accelerator Technology and Sustainability

14:00 Development of low period cryogenic permanent magnet undulators

Undulators are widely employed on accelerator-based light sources. The length of these devices is usually constrained by the length of the straight sections, and this will become even more critical for Diffraction Limited Storage Rings based on existing Synchrotrons, where the number of magnets required to store the electron beam is huge. Thus, to reach high brightness and flux, the total number of periods of undulators must remain large and the magnetic period values will be reduced. Cryogenic Permanent Magnets Undulators (CPMU) are a solution to keep a high peak field value while decreasing the magnetic period. Planar CPMUs have become widely adopted in Synchrotrons worldwide and some laboratories are developing equivalent devices providing also elliptical polarizations. A review of low period CPMU installed on accelerator-based light sources will be presented and sustainability of these sources will also be discussed.

Speaker: Mr Mathieu VALLEAU (Synchrotron soleil)

MOI7M01_edited_version.pdf

Seminar_IPAC26_VALLEAU.pptx

14:30 HTS technology development for energy efficient magnets in PSI Large Research Facilities

Over the past decade, the Magnet Section at the Paul Scherrer Institute (PSI) has developed extensive expertise in superconducting magnet design, construction, and testing, forming the foundation for SMILE (Superconducting Magnets to Improve Large Research Facilities Efficiency) - a proposed R&D initiative that brings together PSI experts and international partners. SMILE’s primary goal is to enhance magnet performance while significantly reducing energy consumption and CO₂ emissions across PSI’s large research facilities. This presentation outlines the future roadmap for advancing High Temperature Superconductor (HTS) technology at PSI’s High Intensity Proton Accelerator (HIPA) complex. A key focus is the development of cryocooler-based HTS magnets for both DC and ramping applications, addressing the unique challenges of operating conduction-cooled HTS tapes in dynamic field environments. Additionally, a critical research area focuses on understanding and mitigating radiation-induced degradation in HTS materials, essential for magnets operating near high-intensity targets. This combined focus on performance enhancement, energy efficiency, and radiation resilience aims not only to reduce PSI’s power consumption and environmental footprint, but with meaningful contributions impacting the research related to the industrial use of the HTS magnets.

Speaker: Stephane Sanfilippo (Paul Scherrer Institute)

MOI7M02_edited_version.pdf

MOI7M02 Sanfilippo.pdf

MOI7M02 Sanfilippo.pdf

MOI7M02 Sanfilippo.pptx

15:00 Commissioning of the RF System for High Energy Photon Source

The High Energy Photon Source (HEPS), recently commissioned in Beijing, is a 6 GeV diffraction-limited storage-ring light source. A double-frequency RF system was adopted, comprising five 166.6 MHz superconducting RF (SRF) cavities acting as the fundamental and two 499.8 MHz SRF cavities serving as the third harmonic for bunch lengthening. A β=1 quarter-wave SRF cavity was developed in-house to achieve the low RF frequency and high power within a compact longitudinal space, while also enabling heavy damping of higher order modes. Solid-state amplifiers provide a total installed RF power of 2.4 MW to drive the cavities in both the booster and the storage ring. A digital low-level RF system was also developed in-house and is current in stable operation. A beam current of 100 mA was successfully achieved using the nominal SRF setup. The design, construction, and commissioning results of the HEPS RF system are presented.

Speaker: Pei Zhang (Institute of High Energy Physics, University of Chinese Academy of Sciences)

MOO7M01_talk_edited_version.pdf

15:20 Tapered APPLE undulators at TPS

To generate white beam with various polarization, we have designed and constructed tapered APPLE undulators. A typical APPLE adjusts the polarization and photon energy through four-axis phase motions and a single-axis gap change. In addition to these mechanisms, our design incorporates rotational and translational structures to further extend the accessible energy spectrum. In this configuration, the magnet arrays must rotate by more than 4 mrad, and such operation results in upstream and downstream gap differences exceeding 10 mm. Achieving reliable actuation for this substantial tapered motion is a critical task. The work reports the latest progress in the design, fabrication, and measurement of the tapered APPLE undulator.

Speaker: Ting-Yi Chung (National Synchrotron Radiation Research Center)

MOO7M02_talk_edited_version.pdf

Tapered APPLE undulators at TPS_DS.pdf

Tapered APPLE undulators at TPS_DS.pptx

15:40 Machine learning techniques for design of complex accelerator magnets

The design of multipole and other magnets for accelerators is typically an iterative process in which the magnet geometry is optimised for the required beam dynamics properties. Modelling the field for a given geometry can be computationally expensive, so exploring the parameter space can be a time-consuming procedure. The task is particularly challenging when complex field properties are needed (for example, in magnets with several multipole components or with longitudinal field variation). Combined function magnets with several multipole components are particularly useful in accelerators with tight spatial constraints such as an X-ray Free Electron Laser (XFEL). Surrogate models using neural networks can provide a way of rapidly generating possible magnet geometries for given field or beam dynamics requirements. In this contribution, we discuss how machine learning tools may be used to improve the efficiency of the design process for complex accelerator magnets, and present results from a case study based on a combined function magnet for the beam spreader in a future XFEL.

Speaker: Sophie Gresty (University of Liverpool, Cockcroft Institute)

MOO7M03_edited_version.pdf

16:00 → 18:00 Poster session

16:00 1.6 MW, 144 MHz solid state power amplifier for ELSA electron linac

The 19 MeV electron linear accelerator ELSA at CEA DAM has been in operation for 30 years. A renovation of the RF system was necessary to improve the reliability of the system.
The second part of the renovation concerns the 144 MHz RF amplifier supplying power to the photo-injector.
The former tetrode based amplifier has been replaced by a 1.6 MW Solid State Power Amplifier delivered by Ampegon company. One of the challenges was to design a compact amplifier to keep the same footprint.
This paper will present the amplifier, the tests and the commissionning.

Speaker: Dr Anne-Sophie Chauchat (CEA DAM Île-de-France, Université Paris-Saclay, CEA, Laboratoire Matière en Conditions Extrêmes)

MOP7049_edited_version.pdf

16:00 6D Phase space reconstruction with Multi-Modal Convolutional Neural Network

The six-imensional (6D) phase space distribution of beam is an extremely important indicator of beam performance and provides useful information for understanding the actual state of the accelerator. On the other hand, the beam diagnostics for the 6D phase space is generally difficult and only a projection on a 1D or 2D phase space is usually obtained. We developed an algorithm based on Convolutional Neural Network (CNN) to reconstruct the 6D phase space
with a limited number of transverse beam images in $x-y$ plane. The advantage of this method is that it does not require as many computing resources as conventional back projection techniques. In this presentation, we show through simulation that a six-dimensional phase space can be reconstructed only from 4+4 beam images. An experimental study of the 6D phase space reconstruction in KEK-ATF is also presented.

Speaker: Masao Kuriki (Hiroshima University)

THP3001_edited_version.pdf

16:00 A computational methodology for the efficient AC-225 production via proton irradiation of RA-226

Ac-225 is a crucial isotope for targeted alpha therapy, yet its clinical application is severely constrained by supply shortages. The use of high-intensity proton beams to irradiate Ra-226 targets offers a viable approach to significantly enhance Ac-225 production, as it enables higher yields and greater scalability. However, the process is also accompanied by the generation of other isotopes of actinium, especially the long-lived Ac-227, which challenges the purification process. This work establishes a precise parameterized model that correlates beam energy, target thickness, and cooling time with each other for optimizing Ac-225 production while minimizing Ac-227 impurity levels and target material consumption. We determine the optimal parameters, which effectively maximize Ac-225 yield while controlling impurity levels and target material consumption. This method provides a valuable reference for the efficient production of Ac-225

Speaker: Wencheng Fang (Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences)

MOP8615_edited_version.pdf

16:00 A Flight Simulator for Electron Accelerators and Test Facilities

Next generation electron–positron colliders such as the FCC, CLIC and the ILC require high beam stability and small beam sizes to reach their target luminosities. Meeting these demands requires highly refined Beam-Based Alignment (BBA) techniques, supported by both precise simulations and experimental validation.

In this paper, combined simulation and measurement studies using a newly developed Flight Simulator tool designed to model realistic lattice imperfections, diagnostic performance, and apply corrections in electron accelerators and test facilities are presented. The framework incorporates magnet jitter, wakefield effects, and measurement noise, allowing detailed testing of dispersion-free steering and related BBA procedures. Complementary measurements performed at the Accelerator Test Facility (ATF) were used to benchmark the simulator and verify its predictive accuracy under varying operational conditions.

Speaker: Pierre Korysko (University of Oxford)

MOP1088_edited_version.pdf

16:00 A framework for environmentally conscious design of particle accelerators

Particle accelerators typically use multiple times more electrical energy than the kinetic energy of the accelerated particles, resulting in low plug to beam efficiencies. The resources required for such machines are also substantial. Considering these points, we present a multifaceted approach with which we can calculate both the carbon emission impact for production and operation of particle accelerators, as well as the relative scarcities of materials used and their possible radioactivation during a lifecycle. To demonstrate a comprehensive use case, we apply these methods to the EcoCyclone permanent magnet cyclotron concept and compare to a normal-conducting coil powered cyclotron with the same output particle energy: the IBA Cyclone® Kiube. We find the two machines produce similar lifetime carbon emissions where the electricity supply is more carbonised, but caveats such as differing impacts of different material sourcing apply. We discuss how the calculated impacts may change over time, noting increasing electricity cost with decarbonisation, and argue these analyses should be performed during the design phase of all new accelerators.

Speaker: Alexander Herrod (Ion Beam Applications (Belgium))

MOP7178_edited_version.pdf

16:00 A Hall-probe calibration setup in the temperature range from 300 K to 4 K at European XFEL

Precise magnetic-field measurements are essential for the characterization of both superconducting (SC) and permanent-magnet (PM) undulators. Since the accurate characterization of these devices relies directly on precisely calibrated Hall probes, a dedicated Hall-probe calibration setup for magnetic fields from -2T to +2T has been developed, produced, and commissioned at European XFEL, capable of operating over a broad temperature range from 300 K down to 4 K. This contribution presents the setup and first results.

Speaker: Mikhail Yakopov (European X-Ray Free-Electron Laser)

16:00 A new method for testing the RF Surface Resistance of NEG coated vacuum tubes at 0.3 - 4.6 GHz

This paper explores a new technique for testing the RF resistivity of Non-Evaporable Getter (NEG) thin films. The technique can be applied to tubular samples, which are representative of the beamlines that would be coated within accelerators, and can also be used for pumping property measurements, so a full analysis of NEG coating properties can be made, and a NEG composition with best compromise between resistivity and pumping can be found. The technique allows measurement of RF surface resistance at 0.3-4.6 GHz.
The method was used on uncoated samples of stainless steel and Cu, to demonstrate a clear difference in measured surface resistance, and samples coated with single element Ti NEG. Samples were coated with approximately 3μm thickness, with the columnar NEG coating showing no difference in surface resistance, and dense NEG coating showing a variation in surface resistance from the copper substrate.

Speaker: Ms Eleni Marshall (Science and Technology Facilities Council)

MOP7114_edited_version.pdf

16:00 A report from ISBA25, accelerator school in Shanghai, China

ISBA25 (The 8th International School on Beam dynamics and Accelerator technology) was held from September 1 to 10 in Shanghai, China. This is the 8th school of the ISBA series, which is a international accelerator school for graduate students and young researchers who are new to the accelerator field. The school curriculum is composed of fundamental topics (e.g., RF theory), applications (e.g., medical accelerators), and the latest topics (e.g,. AI in accelerators). More than 90 students from around the world participated and spent meaningful days, including Hands-on training for accelerator design, student presentations, a laboratory tour of SARI, and an excursion. The school is reported.

Speaker: Masao Kuriki (Hiroshima University)

MOP8619_edited_version.pdf

16:00 A sliding mode control approach for photon beam stability at the Siam Photon Source

This paper presents the enhancement of photon beam position stability at the Siam Photon Source (SPS) through a real-time feedback control system based on a Sliding Mode Control (SMC) algorithm. The proposed system employs Photon Beam Position Monitor (pBPM) measurements within a global orbit feedback loop to minimize beam position fluctuations. The SMC-based Fault-Tolerant Control (FTC) algorithm enhances system robustness by effectively compensating for disturbances, and actuator faults, thereby maintaining stable beam conditions under various operational scenarios. Experimental results demonstrate that the integration of SMC significantly reduces photon orbit deviations and improves synchrotron radiation quality. By strengthening reliability and adaptability, the developed control system ensures precise beam positioning, making the SPS more dependable for scientific and industrial applications that demand high beam stability.

Speaker: Thakonwat Chanwattana (Synchrotron Light Research Institute)

MOP6673_edited_version.pdf

16:00 A study of beam loss data analysis for the high energy photon source

The High Energy Photon Source(HEPS) is China's first and world-leading fourth-generation high performance synchrotron radiation light source. To meet beam commissioning requirements and better monitor the beam status of HEPS, a beam loss measurement(BLM) system based on scintillator detectors has been designed and installed. We conducted a quantitative analysis of beam loss data using neural networks that integrated the BLM system with the beam current measurement system, which achieved an accuracy close to 90%.This approach assists in beam loss diagnosis, helps optimize factors contributing to beam loss, reduces potential damage to superconducting cavities and sensitive components, and ensures the stable operation of the machine.

Speaker: junjie ren (Institute of High Energy Physics)

16:00 Absolute pulsed-mode, long-duration integral field instrumentation using a multi-sensor approach

A recent upgrade of the CERN Super Proton Synchrotron (SPS) quadrupole magnet measuring system enables high relative accuracy on the order of $10^{-5}$ over cycle sequences up to 800 seconds long, as needed for machine-learning based modeling and control of hysteresis effects in the frame of the Efficient Particle Accelerator (EPA) initiative. A new fluxmeter assembly integrates multiple arrays of PCB induction coils with Hall probes and local coils for in-situ cross-calibration, while new FFMM (Flexible Framework for Magnetic Measurements) C++ classes provide automation of complex excitation current cycles, data reduction and database storage. A Python data processing pipeline uses Kalman filters to fuse multiple sensors, correcting for integrator drift. This enables absolute measurements even without traditional Nuclear Magnetic Resonance (NMR) probes, which operate only in uniform fields.

Speaker: Abhishek Ganesh (European Organization for Nuclear Research)

MOP7069_edited_version.pdf

16:00 Accelerator performance drift compensation with a modified MG-GPO Algorithm

Performance drift has been a longstanding problem for accelerators. A desirable solution is to tune the machine slowly and gently to compensate for such drift. Previously, we presented a version of the Multi-Generation Gaussian Process Optimizer which tunes accelerator settings during operation to maintain optimal performance. In this paper, we present an improved version of the algorithm and its application test examples, in which it corrects deviations from the ideal orbit caused by a drifting orbit corrector magnet and a drifting injection kicker magnet respectively. The modified algorithm takes measures to ensure the accuracy of the Gaussian process regression models and to improve the validity of the new trial solutions. We demonstrate that this is a promising development toward using safe, real-time tuning algorithms during accelerator programs to compensate for performance drift.

Speaker: Ryan Yeung (Michigan State University)

MOP6317_edited_version.pdf

16:00 Accelerator-driven radiation studies of YSZ-MgO composites for nuclear applications

YSZ and YSZ-MgO thin films were deposited on Si (100) substrates using RF sputtering and RF-DC co-sputtering techniques and studied under low-energy heavy-ion irradiation. Two sets of films were prepared: YSZ sputtered in argon environment and YSZ and Mg co-sputtered in argon and oxygen environment. Irradiation studies show enhanced crystallinity in single-component YSZ and significant degradation of YSZ crystallinity in YSZ-MgO films. These results indicate a strong dependence of radiation response on composition of the material.

Speaker: Rishvana Parveen (Applied Science Cluster UPES)

MOP8617_edited_version.pdf

16:00 Active supervision for AGS bunch-merging with LLM-based reinforcement learning

Radio-frequency (RF) bunch-merging gymnastics is used in the RHIC heavy-ion program to combine individual source pulses into single bunches with suitable intensity. Preserving intensity and emittance during these gymnastics requires careful coordination of the voltages and phases of RF cavities at several harmonic numbers, which is labor-intensive and fragile against machine drift. Recent work using a physics-based simulator of the Brookhaven Alternating Gradient Synchrotron (AGS) has shown that reinforcement learning (RL) can learn effective merge configurations. RL is data-intensive and requires many training interactions with the environment. Large language models (LLMs) have recently demonstrated the ability to extract patterns from large, noisy data and to integrate domain knowledge into the control loop, making them an attractive aid for tuning complex accelerator systems. However, domain adaptation (i.e., prompt engineering, finetuning, etc.) is always required for deploying LLM in the target domain and has not been investigated in particle accelerators. To fill this gap, we propose an active supervision framework in which the LLM-based teacher first transfers general control principles from human operators to the student agent. Then, the student agent further finetunes the control policy by interacting with the simulator/experiments with improved sample efficiency.

Speakers: Yinan Wang (Rensselaer Polytechnic Institute), Mr Yue Zhao (Rensselaer Polytechnic Institute)

MOP6336_edited_version.pdf

16:00 Adaptive Reinforcement Learning Control for Long-Duration Stability of FEL Operation

During operation of free-electron laser (FEL) facilities, the beam trajectory is highly susceptible to parameter sensitivities, real-time drifts, and environmental disturbances, leading to significant degradation of beam quality. Conventional control methods rely on accurate system models and struggle to handle uncertainties, nonlinear couplings, and dynamic perturbations encountered in real-time operation. To address these challenges, this work proposes an online beam optimization method based on Multi-Agent Proximal Policy Optimization (MAPPO). By enabling collaborative policy learning among multiple agents within a shared environment, the approach achieves distributed, adaptive control of FEL subsystems, effectively captures inter-subsystem couplings, and sustains high performance under dynamic conditions. Experiments conducted at the Shanghai Soft X-ray Free-Electron Laser (SXFEL) facility demonstrate that, compared to PID control and single-agent reinforcement learning, the proposed MAPPO-based method achieves significantly improved long-term stability and exhibits superior robustness under high-noise and strong-perturbation scenarios. These results validate its practicality, reliability, and technical advantage for efficient online deployment in advanced FEL systems.

Speaker: Bowen Zhang (Shanghai Advanced Research Institute)

16:00 Additional installation effort for the 3MW readiness at ESS

Since the last installation campaign, additional High-Beta (HB) cryomodules (CM) have been tested and qualified Ready-for-Installation (RFI) at the ESS Test Stand. Their installation was planned for the summer’25, right after the first Beam On Dump (BOD) commissioning phase and a complete warm-up of the accelerator. The number of HB CM has raised to 11 out of 21 allowing for a potential maximum power of the Linac of 3 MW. This paper will present the lessons learned from the previous phase as well as the necessary measures taken in order to install 6 cryomodules in a RP controlled area in only 3 months.

Speaker: Mr Artur Krawczyk (European Spallation Source)

MOP7037_edited_version.pdf

16:00 Advances in magnetic field quality for ZEPTO tunable permanent magnet quadrupole

The Zero Power Tuneable Optics (ZEPTO) project at STFC Daresbury Laboratory has developed several prototype permanent magnet quadrupoles (PMQs) with the largest tuning range so far demonstrated for any PMQ. By moving permanent magnet blocks relative to fixed steel structures that define the flux path,gradient is adjusted whilst homogeneity remains defined by the steel shape. Maintaining stable field homogeneity and magnetic axis position during adjustment remains a challenge that requires extremely high precision in manufacture and assembly to achieve. Based on lessons learned from the latest ZEPTO prototype, which ran for 2 years on Diamond Light Source, we have developed a fourth prototype which will be installed on the CLARA linear accelerator. This has 2 key developments over the previous prototype to overcome difficulties in manufacturing and assembly precision. If measurements show poor magnet harmonics or axis shift as a function of gradient, these are correctable in the new prototype without re-assembling the magnet or re-machining components. We show that by magnetic steel shims in defined patterns we can correct higher order field components, and that by removing rods of material from the yoke in pre-defined patterns we can tune or add field saturation in one half of the magnet to correct magnetic axis movement. This represents the next step into bringing this technology into direct competition with electromagnets in terms of convenience and reliability.

Speaker: Alexander Bainbridge (Science and Technology Facilities Council)

MOP7166_edited_version.pdf

16:00 Advances in Plasma Processing for Medium- and High-Beta Cavities of the ESS Linac

Plasma processing is increasingly recognized as an effective technique for mitigating field emission and restoring the performance of superconducting radiofrequency (SRF) cavities. A collaboration among CEA, ESS, and INFN is currently working to adapt and optimize this method for the medium- and high-beta elliptical cavities installed in the ESS linac.
This contribution summarizes the ongoing efforts toward implementing plasma processing both in fully assembled cryomodules and in cavities prepared for vertical testing. Here, we present the first experimental results obtained on a medium-beta 704 MHz cavity equipped with different couplers, along with preliminary investigations carried out on the high-beta 704 MHz cavity.

Speaker: Daniele Sertore (Istituto Nazionale di Fisica Nucleare, Laboratori Acceleratori e Superconduttività Applicata)

MOP7032_edited_version.pdf

16:00 Advancing accelerator components design through Additive Manufacturing

Additive manufacturing (AM) enables new design approaches for accelerator components by allowing internal features, such as conformal cooling channels, to be integrated directly into parts. At the ISIS Neutron and Muon Source, development began with a polycarbonate cooling jacket for an RF plasma chamber, later replaced with glass-filled nylon due to sealing limitations. The work was extended to metal AM, including a stainless-steel beam dump produced by direct metal laser sintering (DMLS), demonstrating the need for selective post-machining of sealing surfaces. These lessons informed the design of an ion source main flange with internal cooling channels, successfully prototyped, machined, and validated using neutron imaging at the IMAT instrument. Current research focuses on ceramic AM for plasma chambers, integrating cooling channels within the ceramic wall to allow closer RF coil placement. A digital-light-processing (DLP) printed alumina green-body chamber has been produced as a proof of concept, supporting future development in aluminium nitride (AlN) and multi-material ceramic–copper systems for improved thermal management and performance improvements.

Speaker: Mr Sankar Raj Rajendran (ISIS Neutron and Muon Source)

MOP7176_edited_version.pdf

16:00 Advancing ultra-high-frequency accelerators through metal additive manufacturing

To reduce the footprint and construction costs of RF accelerators, there is a growing interest in operating at ultra‑high radio frequencies in the range of 0.3–3 GHz. At these frequencies, the longitudinal and transverse dimensions of accelerating structures shrink significantly, complicating the fabrication of intricate geometries and intensifying cooling challenges caused by high RF power densities. Metal additive manufacturing offers a promising solution by enabling the efficient realization of complex accelerator components while providing greater design flexibility to enhance overall performance. This paper focuses on the development of next-generation ultra-high-frequency accelerators and presents key results and highlights from ongoing metal additive manufacturing projects at GSI.

Speaker: Chuan Zhang (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Agentic AI as a Middle Layer for Accelerator Control: Multi-Facility Deployment and Early Results

Agentic artificial intelligence (AI) systems are emerging as a practical middle layer for intelligent, self-optimizing accelerator operations. Building on work at the Advanced Light Source, we have developed a modular agentic framework that integrates natural-language interfaces with control systems, archival data, simulation tools, and technical documentation, enabling context-aware reasoning with human-in-the-loop execution. This approach provides intuitive access to complex accelerator environments while preserving safety, transparency, and reproducibility.

A central focus of the framework is usability and rapid onboarding. Self-contained tutorials, reproducible deployment patterns, and a facility-agnostic interface allow laboratories to adopt agentic workflows with minimal customization. This streamlined process has supported deployments at APS, SLAC, SNS, CEBAF, ALS, and BELLA as part of a DOE/MOAT effort within the Genesis mission, where agents execute multi-step tasks, generate inspectable plans, and analyze historical and live data through a shared language interface.

This contribution presents the core architecture, cross-facility deployment experience, and early operational lessons from these implementations. It also outlines how agentic workflows form a unifying layer for emerging capabilities, such as physics-informed optimizers, reinforcement-learning agents, and automated tuning assistants, advancing autonomous control in next-generation scientific facilities.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

16:00 AI-based diagnostics for the cryogenic and RF systems of the SPIRAL2 superconducting LINAC

The SPIRAL2 superconducting LINAC at GANIL operates 26 quarter-wave resonator cavities whose online diagnostics currently rely on physics-based models limited to single operating points. This paper presents two complementary AI-based diagnostic tools: (i) neural-network heat-load virtual observers that estimate the cavity thermal dissipation — a proxy for the intrinsic quality factor Q0 — from cryogenic process signals, with prediction errors predominantly in [−2, +1] W@4.2 K for loads up to 20 W@4.2 K; and (ii) a machine-learning pipeline meant to detecting anomalies in LLRF data, predicting alarms before they fire, and classifying fault subtypes within the cavity-quench category ($F_1$ = 92%). This paper presents a state of progress on these two applications.

Speaker: Charly Lassalle (Grand Accélérateur National d'Ions Lourds, Université de Caen Normandie)

MOP7020_edited_version.pdf

16:00 AI-Enabled Adaptive Control of Beam Current in an Isochronous Cyclotron Using GA-Tuned PID

The 76-inch isochronous cyclotron at UC Davis is being modernized for digital control and data-driven optimization. A key challenge is stabilizing the extracted proton beam current, currently done by manually adjusting Trim Coil 10 (TC10) against magnetic drifts and source fluctuations.

This work develops a digital single-input single-output (SISO) controller that automates TC10 to regulate beam current. The system combines classical PID feedback with data-driven optimization, using a genetic algorithm (GA) to adaptively tune PID gains in the cyclotron’s non-stationary environment.

We have implemented a 200 Hz data-acquisition and control pipeline with beam diagnostics, digital logging, and a Python-based control layer for autonomous operation. Current efforts focus on characterizing the beam’s response to TC10, identifying operational regimes, and validating the GA-tuned PID controller under varying machine conditions. This adaptive system forms a practical foundation for future AI-based multivariable optimization of cyclotron operation

Speaker: Eric Prebys (University of California, Davis)

MOP6342_edited_version.pdf

16:00 AI-Enabled Digital Twins and Optimization Workflows for Accelerator Control

We propose to develop advanced ML models, such as physics informed neural network (PINN) based surrogate models, to accurately represent accelerator phase space transport. These surrogate models will enable precise diagnosis and prediction of beam phase space evolution along the beamline, facilitating real-time control and optimization. The developed models will be tested using the Upgraded Injector Test Facility (UITF) at Thomas Jefferson National Accelerator Facility (JLab), providing a pathway toward ML-driven enhanced diagnostics and beamline control in operational accelerator environments. The primary aim will be to facilitate this by developing machine learning models that outperform traditional simulations in speed and precision. We will build a virtual beamline, train a reinforcement learning (RL) controller across varied calibration scenarios, and then transfer it to the real machine. Beyond operation, fast and accurate models are also essential for design optimization workflows using machine learning methods that iterate through design parameters. A long-term goal of this work will be to establish such workflows and apply them to the design of a compact accelerator at Old Dominion University (ODU).

Speaker: Balsa Terzic (Old Dominion University)

16:00 AI-ready lattice representation and ML optimization for the BNL booster-to-AGS transfer line

As part of the Nuclear Physics AI-Ready Accelerator Data (NARAD) project, Brookhaven National Laboratory is developing a demonstration use case based on the Booster-to-AGS (BtA) transfer line. We establish an AI-ready representation of the BtA lattice using the Particle Accelerator Language Standard (PALS), extended with semantic metadata linking lattice elements to control system signals and device capabilities. This NARAD-PALS model enables direct mapping between simulation, operational devices, and machine data. We implement this framework for the BtA line and demonstrate semantic device queries and control-channel resolution within the BNL Accelerator Device Objects (ADO) system. This unified representation supports integration of streaming and archived data and provides a foundation for ML-based optimization of AGS injection and cross-facility interoperability.

Speaker: Dr Todd Satogata (Thomas Jefferson National Accelerator Facility)

MOP6311_edited_version.pdf

16:00 ALBAII vacuum system: design evolution and prototyping

ALBA is upgrading its storage ring into a 4th-generation diffraction-limited facility, which demands redesigned vacuum chambers. Most of the 268.8 m ring, divided into 16 arcs, will use OFHC-Cu or CuCrZr to dissipate synchrotron radiation and minimize resistive-wall impedance. To meet the injection-efficiency re-quirements, former 16 mm circular cross-section has been replaced by a rhombic geometry providing a 22 mm hori-zontal aperture, 1.25 mm wall thickness and clearances of 1 mm to the magnet poles. Its structural response shows 13 MPa maximum stress with deformations of 3 µm. A short bellows is foreseen between each pair of BPM blocks to absorb chamber displacements from alignment tolerances and thermal expansions while keeping BPM positions fixed. At dipole positions, antechambers with crotch absorbers manage the radiation heat load, with each arc receiving 20.5 kW of power. The entire ring will be NEG-coated to accelerate conditioning and reach the required pressure of 1×10⁻⁹ mbar at 100 Ah. This contri-bution presents the vacuum system status and the design, fabrication progress of the prototypes.

Speaker: Ricardo Parise (ALBA Synchrotron (Spain))

MOP7096_edited_version.pdf

16:00 ALS-U SR modules prestaging planning tool and methodology

The Advanced Light Source Upgrade (ALS-U) project faces strict schedule requirements demanding rigorous planning of manufacturing assembly activities well in advance of assembly and installation. Delays of module components, and changes to the module tunnel installation sequence may significantly impact the module assembly (Prestaging) schedule for all 48 Storage Ring (SR) modules and therefore the installation of those modules during the 9-month SR removal and darktime installation period. To assess the adherence to schedule requirements, Prestaging developed a Visual Basic for Application coded planning tool to automate estimation of SR module assembly duration and resource needs. The tool methodology is based on bottom-up task sequencing where individual assembly tasks are laid out in succession with adjustments made for resource constraints and equipment conflicts. The model processes schedule and resource needs across 5 resource types for approximately 35 assembly tasks per module, generating duration estimates and resource profiles for SR module production. Functional testing has demonstrated the tool's capability to reduce planning time from approximately 4 hours of manual work per scenario-to-scenario processing to minutes while reducing inherent human error. With the model, Prestaging can quickly react to module component delays ensuring assembly planning is optimized within the constraints of the project. This contribution describes the model development methodology, functional testing results, and applications for future use during the ALS-U module assembly phase.

Speaker: Dmitry Gudkov (Lawrence Berkeley National Laboratory)

TUP7368_edited_version.pdf

16:00 Amorphous Carbon Thin Films for Electron Cloud Mitigation in the LHC Arcs: Developments Towards In-situ Implementation

The electron-cloud-induced heat loads on the cryogenic system of the LHC at CERN, which exhibited unexpectedly high values over LHC’s Run 2 and 3, are recognized as a critical limitation to the achievable High-Luminosity LHC beam intensity. Amorphous carbon thin films, sputtered on the inner surface of the beam pipe and exhibiting a low Secondary Electron Yield, have proven to efficiently limit electron cloud build-up. This contribution presents the development, prototyping and validation phases towards the in-situ deployment of amorphous carbon coatings over more than 10 kilometers of beam screen in the LHC arcs during the Long Shutdown 3 (2026-2029). The films are deposited using an assembly of 4 mobile graphite targets, being displaced along the 47 mm-diameter and 53.5 m-long beam lines. The design of the coating system, the characterization of the coatings, particularly under electron irradiation at 15 K and the validation of the process in a full-scale mock-up are presented, highlighting the constraints for upscaling the technology to kilometers of vacuum pipes within the geometrical restrictions of the LHC superconducting magnets.

Speaker: Valentine PETIT (European Organization for Nuclear Research)

16:00 An alternative HOM load design for the EU HOM damped cavity

For the 500 MHz cavities in the main storage ring of SLS 2.0, we plan to manufacture additional spares of the higher order mode (HOM) loads. We saw the current design using ferrite tiles as too risky for us to produce, so we did a redesign using silicon carbide (SiC) blocks, used already with good results for HOM damping in the SLS 2.0 stripline kickers. For good performance specially near cutoff, a prolonged load geometry allows the SiC blocks to taper in smoothly. Up to 1200 watts HOM power can be accepted by the load. SiC being quite tolerant to heat up, we rely on black body radiation for cooling resulting in a more homogeneous heat load distribution of the containing waveguide. The load is cooled by water circuits integrated into the waveguide ridges. Two dedicated pumping ports and an optical view port complete the technical design. Even taking into account possible large variations in the RF properties of SiC, we expect a quite satisfactory performance with a RF match better than 10 dB near the waveguide cutoff and even better than 20 dB for frequencies above 1 GHz. A prototype is currently under production and will undergo lab tests under nominal conditions this summer.

Speaker: Micha Dehler (Paul Scherrer Institute)

MOP7016_edited_version.pdf

16:00 Analysis of remaining fatigue life of edge-welded bellows for LHC collimators

Following the detection of several edge-welded bellows (EWBs) leaks in the Large Hadron Collider (LHC) beam intercepting devices, an investigation campaign was initiated to better understand the fracture behaviour of EWBs subjected to lateral stroke loading. The campaign led to dedicated experimental fatigue tests performed on multiple EWB geometries, originating from different production batches and tested at various cyclic amplitudes. The effects of bake-out and the evolution of leak-rate during cycling were also evaluated. Supported by metallographic analyses of membrane edge-weld fractures, the study revealed a wide spread in EWB fatigue life.
Experimental results, combined with real movement data from EWBs installed in the LHC, were used to estimate the remaining fatigue life of EWBs used in LHC collimators. This analysis enabled the optimisation of EWB motion profiles to extend service life, the identification of collimators at risk of developing leaks, and the development of mitigation strategies to minimise operational impact. The findings highlight the importance of high safety margins when designing critical components whose service life is governed by fatigue mechanisms.

Speaker: Tristan Calvet (European Organization for Nuclear Research)

16:00 APOLLO: a facility-scale differentiable virtual accelerator for Fermilab

As the design complexity of modern accelerators grows, there is more interest in using advanced simulations that have fast execution time or yield additional insights like gradients. The FAST/IOTA facility has been working on implementing and experimentally validating an end-to-end digital twin that is both fast and gradient-aware, allowing for rapid prototyping of new software and experiments with minimal beam time costs. Our framework integrates physics and ML codes for linac and ring simulation through a set of generic interfaces between surrogate and physics-based sections. To reproduce device inputs and outputs, system state is exposed as a deterministic discrete event simulator. Both EPICS and ACNET frontends are supported and can operate in parallel. Recently, we transitioned to the new PALS community lattice standard, expanding use-cases to other facilities. We are also developing infrastructure for data ingest and normalization/tokenization to support running model calibration techniques from simple parameter fitting to full Bayesian inference. All of the above functionality is currently being validated during IOTA proton injector commissioning. We discuss implementation details as well as challenges, and future plans to extend modelling to main complex proton accelerators - PIPII and Booster.

Speaker: Nikita Kuklev (Fermi National Accelerator Laboratory)

16:00 Application of novel RF direct sampling electronics for SHINE cavity BPM

Shanghai High Repetition Rate XFEL and Extreme Light Facility (SHINE) is a continuous wave superconducting linear accelerator. It is the largest Chinese investment in scientific infrastructure ever. In order to achieve measurement of the electron beam position with a resolution of over 200 nm in the undulator, a new RF direct sampling electronics for the SHINE cavity BPM system was developed, which directly samples the 5.254 GHz cavity BPM signal at 2.6 GSPS with a processing speed of 1 MHz. Compared to traditional electronics, which rely on complex analog down-conversion before digitization, this system greatly simplifies the front-end by removing the need for down-conversion phases and achieving comparable performance. This is the first time that a batch of RF direct sampling electronics for cavity BPMs on a FEL has been introduced. In this paper, we will present the developed and deployment of the RF direct sampling electronics for SHINE cavity BPM.

Speaker: Yuxin Han (Shanghai Institute of Applied Physics)

16:00 Application of Pyapas in PWFA

The Plasma Wakefield Acceleration (PWFA) experimental platform consists of two beamlines. Beamline 1 (BL1) transports the electron-positron beams from the BEPCII linear accelerator to the experimental station, with a beam energy of 2 GeV. Beamline 2 (BL2) is a linear accelerator featuring an energy of 150 MeV and a bunch charge exceeding 5 nC. Currently, both beamline accelerators have entered the beam commissioning phase. Pyapas, an independently developed High-Level Application (HLA) by the Institute of High Energy Physics (IHEP), has been successfully applied to beam commissioning of high-energy light sources. We have achieved the successful porting and application of Pyapas in the beam commissioning of the PWFA linear accelerators.

Speaker: Haisheng Xu (Institute of High Energy Physics, Chinese Academy of Sciences)

MOP6701_edited_version.pdf

16:00 Application of Wall Current Monitor at CSNS Rapid Cycling Synchrotron

Two sets of Wall Current Monitors (WCMs) have been installed in the Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) to fulfill three core beam diagnostic objectives: synchronous measurement of longitudinal bunch shapes across both macro and micro scales, accurate calculation of longitudinal emittance, and effective diagnosis of beam instabilities. This article focuses on the comprehensive discussion of the entire WCM system (probe and DAQ system) and its practical application during CSNS-RCS beam commissioning. The WCM system has performed quite well during the beam commissioning over the past years.

Speaker: Weiwen Chen (Institute of High Energy Physics)

MOP6629_edited_version.pdf

16:00 APS-RAG: A domain-aware hybrid retrieval augmented generation system for accelerator operations and knowledge synthesis

Effective knowledge management is essential to minimize downtime and maintain institutional memory in large-scale accelerator facilities. We present APS-RAG, a domain-aware Retrieval-Augmented Generation (RAG)* system currently deployed at the Advanced Photon Source (APS), designed to synthesize operational intelligence and facilitate semantic data retrieval from various dispersed databases. The system consolidates over 10,000 unique documents from four live databases: the BELY scientific electronic logbook, operational Microsoft Teams chat, the Integrated Content Management System (ICMS), and Work Request system. By employing the latest frontier LLMs via Argonne’s ARGO AI platform, APS-RAG integrates a specialized query preprocessing pipeline that performs temporal parsing, domain acronym resolution, multi-query expansion, and final response generation.

To ensure high precision, a hybrid retrieval architecture is utilized, combining dense vector and keyword search. The results are aggregated using Reciprocal Rank Fusion (RRF) and refined through cross-encoder reranking to maximize relevance**. An 100-question evaluation dataset was built using InPars methodology***, supplemented with qualitative user feedback. The final responses from APS RAG have inline citations embedded which displays the source document chunk and a web accessible link to the original document. Future developments include multimodal integration and agentic knowledge graph capabilities****.

Speaker: Yine Sun (Argonne National Laboratory)

MOP6302_edited_version.pdf

16:00 Ariel: Agentic retrieval interface for electronic logbooks

Operational logbooks are essential for documenting accelerator performance, interventions, and operator experience, but their content is often inconsistent, unstructured, and difficult to search. This limits both human retrieval and the use of AI systems that rely on high-quality historical data. Project ARIEL (Agentic Retrieval Interface for Electronic Logbooks) introduces a modular, facility-agnostic framework that standardizes how logbook information is ingested, enriched, and searched across accelerator laboratories. Each participating site hosts its own ARIEL database while adopting a shared schema, data-enhancement modules, and interoperable search components. Enhancement modules provide semantic metadata, text and figure embeddings, and optional machine-state snapshots at ingestion time. On the retrieval side, ARIEL supports keyword, embedding-based, multimodal, and machine-state search, forming a unified foundation for an agentic retrieval layer capable of orchestrating multiple search strategies. This contribution presents the architecture, schema design, and early cross-facility prototypes, and describes how ARIEL fits into the broader DOE Genesis AI mission to establish shared, interoperable AI infrastructure for accelerator facilities.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

MOP6326_edited_version.pdf

16:00 Automated Post-Mortem Beam Orbit Analysis in the LHC

After every high-energy beam dump event at the Large Hadron Collider (LHC), the beam orbit before the dump, which is collected as part of the high-resolution post-mortem data, is analysed to identify any anomalous behaviour. This analysis is currently performed manually for both beams in both planes. Statistical methods based on post-mortem beam position monitor data from the years 2022-2024 were developed to automate this analysis. This paper shows that the developed methods perform well on LHC beam dump events to automatically identify orbit anomalies of different durations and patterns.

Speaker: Jan Uythoven (European Organization for Nuclear Research)

16:00 Automated tuning techniques at TRIUMF for the ARIEL era

Implementing automated tuning techniques has been a priority at TRIUMF, driven by the need to support the significant increase in RIB availability expected with the new Advanced Rare Isotope Laboratory (ARIEL). This efficiency boost will facilitate a broad spectrum of research in nuclear, particle, and astrophysics. This work outlines the shift from manual tuning to an automated approach for optimizing beamline transport. We utilize the predictive digital twin, Model Coupled Accelerator Tuning (MCAT), to compute transport and accelerated beam tunes, while Bayesian Optimization for Ion Steering (BOIS) handles beam orbit correction. BOIS treats steering as a black-box optimization problem, maximizing beam current based solely on direct measurement. By combining MCAT and BOIS, this method offers a more efficient, physics-grounded tuning process, with potential applications for facilities beyond TRIUMF.

Speaker: Omar Hassan (TRIUMF)

MOP6390_edited_version.pdf

16:00 Autonomous Planning and Execution of Injector Tuning via the Osprey Agentic Framework

We take a step beyond Operator-supervised optimization by introducing an agent that plans and executes fast, sample-efficient injector tuning constrained by competing goals (capture efficiency, energy spread, transmitted charge).
We present an agent built on the Osprey agentic framework that can (i) author a machine-readable configuration for a configurable online optimizer, (ii) invoke that optimizer as a tool, and (iii) autonomously infer next tuning actions by querying and actuating the control system.
The agent reasons over multi-diagnostic signals and operational constraints, selects objective/constraint formulations, proposes bounded setpoint updates, and schedules measurements; safety is enforced via capability-scoped tool use, guardrails, and machine-protection checks.
Control system integration relies on EPICS get/put/monitor primitives for live state estimation and closed-loop execution.
Initial machine studies at the ALS show the agent can compose full tuning plans—configuring objectives tied to known bottlenecks (e.g., beam-loading–driven energy-spread control relevant to booster acceptance) and launching optimization runs—yielding reduced operator intervention and faster convergence, while preserving capture within the booster ring’s tight longitudinal window.
We summarize the architecture (Osprey capabilities, optimizer interface, EPICS I/O), online decision logic, early results, and a path to portable deployment at other accelerator facilities.

Speaker: Gianluca Martino (Lawrence Berkeley National Laboratory)

16:00 Beam Diagnostics System for HALF Storage Ring

The Hefei Advanced Light Facility (HALF) is a fourth-generation, low-energy diffraction-limited synchrotron light source currently under construction. Its storage ring has an energy of 2.2 GeV, a circumference of 480 meters, and an emittance of 86 pm·rad. To ensure the smooth commissioning of HALF to meet its design specifications and to fully exploit the operational potential of this facility, it is necessary to develop a comprehensive beam diagnostic system with high temporal and spatial resolution. This paper will introduce the overall structure and design of the HALF storage ring beam diagnostics system, focusing on the latest development progress of the high-resolution, high-stability beam orbit measurement and feedback system, and the bunch-by-bunch multi-parameter diagnostic system.

Speaker: Xing Yang (University of Science and Technology of China)

MOP6643_edited_version.pdf

16:00 Beam Dynamics Studies in the SuperKEKB Linear Accelerator and Beam Transport System

The next luminosity milestone at SuperKEKB requires improved emittance preservation of the injected beams, which remains a key limitation of the injector chain. Although emittance growth in the LINAC and beam-transport (BT) lines has been studied previously, the combined impact of collective effects, lattice imperfections, and other uncertainties is still not fully understood.
A major contributor to the horizontal emittance growth is incoherent and coherent synchrotron radiation (ISR/CSR), particularly evident for the electron BT (BTe). The vertical emittance also increases in this region, though its origin is not yet clear. Additional dilution arises from short-range wakefields and lattice misalignments, which amplify trajectory jitter and generate residual dispersion and coupling. Earlier studies did not systematically include these effects. Moreover, recent magnetic-field measurements of the BTe dipoles indicate non-ideal field profiles, motivating the use of representative field maps in the BT lattice.
This study incorporates wakefields, ISR/CSR, realistic alignment errors, and updated BTe dipole fields within a unified tracking framework to quantify their combined influence on emittance growth. The results clarify the dominant limitations in the current injector and support strategies for achieving stable, low-emittance injection in future high-luminosity operation.

Speaker: Andrea Aguirre Polo (Deutsches Elektronen-Synchrotron DESY)

MOP1013_edited_version.pdf

16:00 Beam Halo-to-Core Measurements with a Thin Diamond Detector at WNR

We report on beam characterization studies of an 800-MeV proton beam using a 30-µm-thick single crystal diamond detector at Weapons Neutron Research facility at Los Alamos Neutron Science Center. Owing to its fast-timing response and high radiation tolerance, the detector enabled measurement of beam intensities spanning the full dynamic range from the outer halo to the high-density core. Measurements were performed across multiple operating conditions, including varying extracted charge, pulse repetition rates, and bias voltages. The detector provided stable and reproducible signals throughout, demonstrating its suitability for high-precision proton-beam diagnostics in environments with large intensity variations. These results highlight the applicability of thin diamond sensors for real-time monitoring in high-energy accelerator facilities.

Speaker: Evgenya Simakov (Los Alamos National Laboratory)

16:00 Beam measurements with cryoinserts in SIS18

In oder to increase the maximum achievable intensity of medium charge state heavy ion beams in SIS18 at GSI for FAIR-operation, the installation of cryoinserts is foreseen. These cryogenic surfaces with high sticking probability provide high pumping speed, where most of the beam-loss induced gas desorption takes place. Such, gas particles get quickly removed, minimizing beam loss by charge exchange from interaction with the residual gas.
A prototype cryoinsert was designed, manufactured and tested, showing the clear reduction of artificial gas pulses. Most recently, the prototype was installed into SIS18. There, a reduction of the static pressure extending several meters after cooldown was observed.
In 2025 the first beam experiments with medium charged Uranium beams and the cryoinserts took place to observe their influence. The charge exchange could be measured, showing a significant decrease due to the cryoinserts and also a slight influence on the transmission through an acceleration cycle was measurable.
In the meantime, a series production of cryoinserts is prepared, including improvements and simplifications of the design.

Speaker: Lars Bozyk (GSI Helmholtz Centre for Heavy Ion Research)

MOP7091_edited_version.pdf

16:00 Beam transfer concept at the FCC-ee injector complex

The FCC-ee collider complex relies on continuous top-up injection to maintain the high bunch charge and luminosity required to achieve its physics objectives. The injector complex will generate and accelerate electron and positron beams up to 20 GeV using linear accelerators, while a damping ring is foreseen to reach the emittance levels demanded by the high-energy booster.

This contribution presents the first concept for the injection and extraction systems of the damping ring, including the layout, optics design, and hardware constraints. A possible implementation of the newly introduced polariser ring and its associated beam transfer scheme is also outlined. The beam dynamics and operational scenarios of these transfer systems are discussed, together with the next steps towards defining a baseline layout within the injector complex.

Speaker: Yann Dutheil (European Organization for Nuclear Research)

16:00 Beam-Based Characterisation of BPM Electronics Thermal Sensitivity after Two Decades of Operation

Beam-based measurements of the thermal sensitivity of beam position monitor (BPM) electronics were performed in SPEAR a third-generation storage ring after more than twenty years of routine user operations. Controlled building-temperature excursions were applied to two equipment buildings containing key BPM front-end and digitiser racks. Using orbit- and charge-normalised BPM signals and independent temperature logging, we performed lag-aware regression to estimate effective position-versus-temperature coefficients for each BPM, and compared several alternative temperature-driver models (global, per-building and hybrid). The method was applied to two measurement campaigns, months apart, with different ambient conditions. The results show clearly distinguishable building-level responses and reproducible patterns within subsets of BPMs, but also highlight strong correlations between temperature, beam conditions and slowly varying lattice effects. We present this analysis framework as a step towards robust, beam-based thermal characterisation of ageing BPM systems, and outline how extended datasets could support future BPM upgrades, thermal monitoring and operational orbit-stability tools.

Speaker: Xiaobiao Huang (SLAC National Accelerator Laboratory)

MOP6338_edited_version.pdf

16:00 Beam-delivery challenges for plasma-wakefield accelerators

Plasma-wakefield acceleration offers a promising path towards a next-generation collider, but poses significant beam-delivery challenges. We present initial designs for final-focusing systems capable of transporting beams from the plasma-based-collider concepts, ALiVE and HALHF, each with distinct beam dynamics constraints. For ALiVE, where the beams are intrinsically round, we demonstrate an increase in L_1%/L_𝑡𝑜𝑡 from 3.6% to 27%, and explore ultra-compact FFS configurations reflecting the potential for significantly reduced collider lengths. For HALHF, where the beams feature large horizontal emittance to alleviate the burden on the plasma linac, we show that a global chromaticity correction scheme reduces aberrations to within 20% of the design beam size at 375 GeV, and identify synchrotron radiation as the dominant limitation at higher energies.

Speaker: Lewis Kennedy (John Adams Institute for Accelerator Science, University of Oxford, European Organization for Nuclear Research)

MOP1041_edited_version.pdf

16:00 Beam-induced heating and thermal analysis for the EIC HSR cryogenic helical magnet and BPM assembly

The EIC Hadron Storage Ring (HSR) reuses the RHIC yellow ring with substantial reconfiguration. A major challenge is mitigating beam-induced heating of cryogenic components caused by the shorter hadron bunches and an average beam current three times that of RHIC. In addition, large transverse beam offsets at injection due to helical magnet itself generate asymmetric resistive-wall losses in the cryogenic BPM region. To limit these losses, the HSR helical magnet assembly uses a new copper-plated stainless-steel beam pipe with an amorphous-carbon coating. This paper presents heating and thermal analysis of the EIC HSR cryogenic helical magnet and BPM assembly. Thermal simulations show narrow thermal margin for the helical magnet unit, and adequate margin for the BPM assembly.

Speaker: Kiel Hock (Brookhaven National Laboratory)

MOP6348_edited_version.pdf

16:00 Benchmarking FLUKA Simulations of Double Channeling and Crystal Alignment Against the TWOCRYST Experiment

The TWOCRYST experiment at CERN is a proof-of-principle setup designed to demonstrate the feasibility of the future ALADDIN experiment, part of the Physics Beyond Colliders programme. The setup comprises two bent crystals installed in the LHC beamline at Insertion Region 3 (IR3). The first crystal (TCCS) extracts particles from the beam and directs them onto the second crystal (TCCP). This paper presents the FLUKA simulations performed to assess the crystals alignment procedures for various beam and crystal configurations. Since the alignment of the crystals is achieved mainly by monitoring the Beam Loss Monitor (BLM) signals in the vicinity of both bent crystals, the main objective of the simulations is to evaluate the corresponding BLM responses at each step of the procedure. These simulations aim to confirm the validity of the alignment process by demonstrating that the BLM signals can be reliably used to gauge proper crystal alignment. The simulation outcomes are presented here and were found to be consistent with experimental observations.

Speaker: Kate Taylor (European Organization for Nuclear Research)

MOP1036_edited_version.pdf

16:00 Bent crystals as multifunctional elements in particle accelerators

Bent crystals, through the phenomenon of channeling, provide compact and passive deflection elements capable of delivering angular kicks equivalent to those of hundreds-tesla magnetic dipoles on selected portions of a beam. They are therefore attractive for a wide range of beam-manipulation tasks in circular proton and ion accelerators, including ion collimation as foreseen for HL-LHC, halo extraction, crystal-assisted focusing and defocusing, and beam-shadowing schemes in the 1-400 GeV range, in which a bent crystal placed upstream of the electrostatic septum slightly pre-deflects a thin slice of the circulating beam to reduce the particle load on the septum wires and thereby lower extraction losses.
We report recent progress in the design, fabrication, and characterization of bent crystals optimized for these applications. Emphasis is placed on curvature control, crystal quality, and high-precision structural diagnostics to ensure reliable and reproducible deflection performance. These developments demonstrate the feasibility and potential impact of crystal-assisted beam steering in future accelerator facilities.

Speaker: Pierluigi Fedeli (University of Ferrara)

16:00 CAD integration for the PETRA IV project

The PETRA IV project at DESY in Hamburg aims for a new, 4th generation light source with first light in 2032. It comprises the installation of a completely new, 2.3km long 6GeV electron storage ring and a new injection chain, installation and refurbishment of 31 photon beam lines with 60 end stations, and the construction and refurbishment of 49 buildings including a new 600m long underground experimental hall.

The project will reuse existing tunnels and halls of the PETRA III light source, and targets a dark time without beam of only 30 months, which is a challenging task that requires thorough planning. To meet this challenge, a comprehensive CAD model has been set up that integrates the data of all participants: construction, photon science, accelerator, campus and logistics.

The model comprises representations of all systems and subsystems in different abstraction levels. A strict structure aligned with the project’s WBS and PBS, extensive use of interfaces, and a focus on review and change management processes ensure that the model is complete, consistent and correct and will remain so throughout the entire life cycle of the project.

Speaker: Benno List (Deutsches Elektronen-Synchrotron DESY)

MOP7186_edited_version.pdf

16:00 Challenges in the Development of the SIS100 Electrostatic Extraction System

The "Facility for Antiproton and Ion Research" (FAIR) is a new international accelerator complex, which is currently built in Darmstadt, Germany. Part of this complex is the SIS100 heavy ion synchrotron with a circumference of ~1086 m. One of the required extraction systems is the electrostatic septum. This septum was built by Danfysik. It is operating with voltages up to 180 kV. The requirements on the vacuum quality (low 10-11mbar region) combined with voluminous chambers (in total ~6m long), the reproducibility and precision of the applied voltage as well the mechanical stability and exact positioning even after bakeout cycles up to 300 °C have been the biggest challenges on this project. Specifications on rise and fall times for the high voltage implies the need of a bleeder resistor, used for improved voltage accuracy, too. During this project numerous problems had to been solved to end up with a stable system. The results of the tests and lessons learned will be presented.

Speaker: Marc Petryk (GSI Helmholtz Centre for Heavy Ion Research)

MOP7151_edited_version.pdf

16:00 Challenges of the Long Shutdown 3 for the LHC: from preparation to execution

The Long Shutdown 3 (LS3) of the Large Hadron Collider (LHC) represents a pivotal phase in the lifecycle of CERN’s accelerator complex. The unprecedented complexity of LS3 arises from the challenge of integrating the High-Luminosity LHC (HL-LHC) upgrade, together with multiple key projects, extensive maintenance and consolidation activities, into a single coherent schedule with a fixed duration of 47 months. Achieving this goal requires precise orchestration of interventions and effective management of resources shared across different facilities. This paper first outlines the LS3 preparation framework for the LHC, with an emphasis on the adopted methodology to accomplish the LS3 objectives and the preparation of the LHC schedule. It also investigates the main challenges associated with LS3 execution and presents the strategies and tools envisaged to address them. A unifying environment for monitoring and reporting is introduced—a platform that integrates interactive dashboards designed to streamline the progress visualisation and ensure a reliable reporting throughout the LS3 period.

Speaker: Michele Loffredo (European Organization for Nuclear Research)

MOP1091_edited_version.pdf

16:00 Characterization of the four-quadrant X-band cavity prototype for the ASTERIX project

The ASTERIX project, hosted by the INFN–LNF, seeks to achieve the first demonstration of a practical, meter-scale X-band RF accelerating structure suitable for operational linear accelerators (>100 MV/m accelerating gradient). The goal is to produce innovative RF structures to qualify as part of the world-wide scientific collaboration (SLAC/CERN/INFN-LNF/KEK/Tsinghua) for R&D in the accelerator development and high-power testing of innovative cavities with high gradients.

The structure is composed of four-quadrants (“open-type”), made of hard copper, joined and vacuum sealed by using TIG welding (“braze-free” technique) through a cost-effective and robust manufacturing.

The full-structure RF design, in single-bunch operation mode, was carried out with the 3D numerical simulation codes Ansys HFSS and CST Microwave Studio.

In this paper, we report on the engineering of the full-structure prototype optimized for low RF power measurements and initial mechanical tests in order to validate the quadrant straightness and alignment, the TIG welding process, the vacuum tightness; etc. The proto-type was fabricated with lower precision of geometric dimensions and more relaxed mechanical tolerances.

Speaker: Zhicheng Huang (University of Science and Technology of China)

MOP7009_edited_version.pdf

16:00 Compact X band 2 MeV Linac for on-site inspection

A compact X-band 2 MeV electron linear accelerator (linac) has been developed for on-site inspection applications, addressing the limitation of hundreds-kV X-ray sources in fully penetrating dense objects during field operations. The linac system comprises three modular units, each weighing less than 65 kg, enabling manual transport by operators without specialized equipment. This paper presents the design principles, comprehensive testing results, and field deployment outcomes of this compact linac. The system demonstrates superior penetration capability, operational flexibility, and reliability in industrial environments.

Speaker: Yongtao Liu (Xihua University)

16:00 Comparative conceptual designs of liquid lead absorbers for the FCC-ee beamstrahlung dump

At CERN’s Future Circular Collider (FCC-ee), the beamstrahlung photon beams produced at each interaction point carry several hundred kilowatts of power, requiring a reliable and thermally efficient absorber. Building upon an initial slope-based liquid-lead concept, this work investigates two improved configurations: 1) a double-slope geometry, designed to mitigate photon backscattering observed in earlier designs; and 2) an inclined slope section with an accumulation pool at the back, intended to maximize photon absorption, reduce system size, and ensure thermal and flow stability. Both concepts operate under an inert argon atmosphere and target an effective absorption thickness of 10–20 cm, with a liquid-lead mass flow rate of approximately 300 kg/s. Monte Carlo simulations are employed to compute photon energy deposition, while multiphase computational fluid dynamics (CFD) analyses characterize the coupled thermal and hydrodynamic behavior. The results compare the performance of the two configurations and identify key parameters for further optimization of the FCC-ee liquid-lead photon dump system.

Speaker: Thomas Banks (European Organization for Nuclear Research)

MOP7139_edited_version.pdf

16:00 Comprehensive integration and innovation on the 1.5 GHz SRF harmonic cavity control system at NSRRC

This paper presents a self-developed, comprehensive electronic control system for the Superconducting Radio-Frequency passive Harmonic Cavity (SRF HC) at the Taiwan Photon Source (TPS) in Hsinchu, Taiwan. The system integrates the Break Out Box (BOB) interfaces for the cavity, Valve Box (VB), cooling water signals, and interlock systems. Additionally, it includes an intuitive correction module and updates for the discontinued or unmaintainable dial gauge module, ensuring that the system operates safely and transparently with clear status display.

Speaker: Ming-Chyuan Lin (National Synchrotron Radiation Research Center)

MOP6700_edited_version.pdf

16:00 Conceptual comparison of liquid lead flow configurations for a muon collider

Liquid lead is under investigation at CERN as a candidate material for a multi MW-Class production target for a future Muon Collider. A free-surface curtain was initially proposed to decouple structural walls from beam-driven shock waves resulting from the high instantaneous energy deposition on the target material. However, later studies revealed that the large vertical extent required for this configuration limits the particle production efficiency, which motivated the development of a jet concept proposed in this work. Because the target operates within a 20 T solenoidal magnetic field, magnetohydrodynamic (MHD) effects are expected to influence the liquid-metal flow. Estimates indicate operation at low magnetic Reynolds numbers, where electromagnetic induction is weak. Nevertheless, the strong applied magnetic field leads to significant Lorentz forces that can affect flow stability and hydraulic performance. Both configurations are analysed using coupled multiphase computational fluid dynamics-magnetohydrodynamics (CFD-MHD) simulations in the quasi-static approximation to investigate current distribution, magneto-hydrodynamic damping, and free-surface deformation. The comparison highlights the main physical trade-offs between the two concepts and defines the framework for ongoing design optimisation.

Speaker: Thomas Banks (European Organization for Nuclear Research)

MOP7137_edited_version.pdf

16:00 Conceptual design of a 0.2 MW pulsed 140 GHz gyroklystron amplifier and studies towards 1 MW operation for accelerator applications

Exploration of accelerator technologies in the millimeter-wave regime offers a promising route to achieve extremely high accelerating gradients. Owing to the high shunt impedance and short filling times of mm-wave accelerating structures relative to conventional S- and C-band systems, GV/m-level accelerating gradients become attainable. Mm-wave accelerator concepts are therefore of strong interest for applications including future linear colliders, charged-particle therapy, compact X-ray free-electron lasers (XFELs), and ultrafast electron diffraction (UED).

We present the conceptual design of a pulsed 140 GHz gyroklystron amplifier intended as an RF power source for mm-wave accelerator systems. The interaction circuit adopts a two-cavity configuration composed of an input cavity, a drift section, and an output cavity. The electron beam is generated by a triode-type magnetron-injection gun (MIG) that provides operational flexibility, enabling adjustment of beam parameters and stable performance across a broad operating range. Design details of the MIG and the two-cavity interaction structure will be presented.

Speaker: Anton Malygin (Karlsruhe Institute of Technology)

MOP7050_edited_version.pdf

16:00 Conceptual design of a novel deuteron accelerator driven neutron source for nuclear waste transmutation

A novel compact neutron source driven by deuteron Cyclotron Auto-Resonance Accelerator (dCARA) is under development to produce neutrons via breakup of high current 40-MeV deuterons on a low-Z target. Compared to the proton-based Accelerator-Driven Systems (ADS), a dCARA system can be much more compact and cost effective, with notable features including continuous acceleration without bunching for good beam stability, high efficiency, wide beam aperture, and an exceptionally short length of few meters. The applications of dCARA include transmutation of used nuclear fuel, medical isotope production system, or material test for a future fusion power reactor. The R&D progress and the conceptual design of dCARA are reported here.

Speaker: Yong Jiang (Particle Accelerator Research Foundation, Omega-P R&D, Inc.)

MOP8306_edited_version.pdf

16:00 Conceptual electromagnetic design of a Magnetised Hadron Stopper for the BDF/SHiP experiment at CERN

SHiP (Search for Hidden Particles) at CERN is a new experiment which aims to explore physics beyond the Standard Model by searching for long-lived, feebly interacting particles, as theoretically predicted by a large number of models.
It will employ a dedicated Muon Shield (MS) to suppress the muon flux generated in proton–target interactions. The first magnet in the MS complex is the Magnetized Hadron Stopper (MHS), which serves a dual purpose: it absorbs residual secondary particles produced in the target region and initiates the deflection of muons with momenta up to 350 GeV/c. To achieve this efficiently, the MHS features an unconventional geometry without aperture, and it shall generate a field of 1.9 T in its core within a compact 2.3 m length.
The paper describes the conceptual design of the MHS, which is driven by the demanding engineering requirements combined with the limited available space and high-radiation environment. The design of the magnetic circuit is achieving the required flux compression while ensuring maintainability in a high-radiation area, including the implementation of a non-magnetic spacer that enables disassembly under residual magnetization.

Speaker: Vittorio Ferrentino (European Organization for Nuclear Research)

MOP7060_edited_version.pdf

16:00 Conceptual magnet designs for MAX 4U

The MAX 4U project aims to reduce the natural horizontal emittance of the MAX IV 3 GeV storage ring from 328 pm rad to less than 75 pm rad. A key constraint for the new lattice design is the preservation of the 7-bend achromat structure layout. Each cell is implemented as a single magnet block, which includes an integrated dipole, removable quadrupole pole tips, and stand-alone sextupoles and octupoles. This configuration imposes strict limitations on the level of intervention possible within each block. This contribution presents conceptual magnetic designs and initial crosstalk studies.

Speaker: Henrique de Oliveira Caiafa Duarte (MAX IV Laboratory)

MOP7068_edited_version.pdf

16:00 Control system upgrades for autonomous beamline control at the Argonne Wakefield Accelerator test facility

The Argonne Wakefield Accelerator (AWA) test facility has recently upgraded its inhouse centralized control system to a modularized system using the EPICS control ecosystem, in a move to align with other large facilities and facilitate external collaboration to explore the implementation of machine learning techniques to beamline control and optimization. In particular, we aim to develop and demonstrate several individual autonomous optimization routines, which can then further be implemented into a sequential optimization routine in effort to automate various complex beam control tasks. We report here on the new control scheme and initial optimization routines so far tested in the commissioning phase of a recently upgraded photoinjector. Additionally, we discuss the near-term plans for further optimization routine testing.

Speaker: Alexander Ody (Argonne National Laboratory)

16:00 Cooling-Tower technologies for the IFMIF-DONES heat rejection system: technical and environmental considerations

The International Fusion Materials Irradiation Facility-DONES (IFMIF-DONES) is a scientific infrastructure intended to test and qualify materials for fusion reactors by exposing them to intense neutron fluxes. Several auxiliary systems will ensure its continuous operation, among which the Heat Rejection System (HRS) is designed to remove and discharge to the environment the heat mainly generated by the Accelerator's primary cooling loops and the Test Cell. While open evaporative cooling towers are widely used for industrial heat rejection, alternative technologies may be more suitable depending on site-specific conditions and project priorities.
Environmental factors—particularly local weather patterns and their expected evolution under climate change—play a decisive role in overall system performance. Their proper assessment is therefore essential for selecting the most appropriate cooling-tower technology.
This work presents a comparative evaluation of candidate heat-rejection solutions to identify the technology that best fits the site conditions, optimises performance over the system's life cycle, and supports the project's commitment to minimising its environmental footprint.

Speaker: Ignacio Sampedro (IFMIF-DONES Spain Consortium)

MOP7180_edited_version.pdf

16:00 Crystal Channelling Optimisation in the LHC Using Reinforcement Learning

The Large Hadron Collider (LHC) requires a collimation system to ensure safe operation with both proton and heavy-ion beams. As of 2023, a crystal collimation scheme using bent silicon crystals was introduced to improve the collimation efficiency for heavy-ion beams. However, drifts in the crystal angular position led to the loss of cleaning performance during physics fills. These drifts are thought to derive from mechanical deformation of the goniometer due to heating caused by beam impedance effects. A quadratic-fit based optimiser was deployed to compensate for such drifts using feedback from beam loss monitors. This paper details the simulation environment to train reinforcement learning agents to maintain the optimal channelling position with increased reliability and reduced convergence time, and presents the latest results obtained with lead ion beams.

Speaker: Andrea Vella (University of Malta)

16:00 Current status and progress of design and commissioning of HELIAC cavities

The HElmholtz LInear ACcelerator (HELIAC) at GSI is a superconducting continuous-wave (cw) LINAC, designed to deliver heavy-ion beams to user experiments at GSI. Building on the successful integration, commissioning and operation of the first cryomodule CM1 utilizing cavities CH0, CH1, and CH2, current efforts emphasize on fabrication and testing of the next series: CH3 - CH8.
Cavities CH3–CH8 have been designed and validated through dedicated advanced simulations. The manufacturing of components for CH3 and CH4 cavities now undergoing electron beam welding. The targeted design resonance frequency of 216.816 MHz will be fine-tuned via buffered chemical polishing (BCP) and compensation procedures to address manufacturing tolerances. The cavity design and tuning strategy will be presented in this contribution.

Speaker: Alexey Gunya (GSI Helmholtz Centre for Heavy Ion Research)

MOP7023_edited_version.pdf

16:00 Current status and recent development of the Xcoll-FLUKA interface

The Xsuite framework offers a modern environment for high-performance accelerator physics simulations. Its Xcoll module handles particle-collimator interactions using dedicated scattering routines, both built-in and external. FLUKA, a well-established Monte Carlo code, can be coupled to Xcoll, enabling detailed modelling of particle-matter interactions and support for complex geometries. This paper presents the status of the Xcoll-FLUKA interface, which provides a consistent and
efficient link between deterministic beam tracking and Monte Carlo simulations. The new setup builds upon the experience gained with the previous SixTrack-FLUKA coupling, introducing a more user-friendly design and significant improvements in data exchange, modularity, and extensibility within the Xsuite architecture. Recent developments include a new filtering algorithm that improves simulation speed,
a versatile definition of bent crystals, support for simplified collimator geometries represented as plain blocks of material, and an enhanced beam-beam interaction routine. These advancements represent an important step toward a flexible and performant framework for collimation and background studies in present and future accelerators.

Speaker: André Donadon Servelle (European Organization for Nuclear Research)

MOP1117_edited_version.pdf

16:00 CURRENT STATUS OF BESSY III MAGNET DESIGN

HZB is developing BESSYIII, a future 4th-generation low-emittance diffraction-limited soft-to-tender X-ray synchrotron light source, as a green-field facility in 2035 on the premises of the Adlershof technological campus in Berlin, Germany. We are in the design phase of magnet concepts for all permanent-magnet (PM-)based linear and resistive multipole magnets, fulfilling the requirements of the CDR-project design of Higher-Order Achromat Multi-Bend Achromat (HOA-MBA) storage ring lattice. Exposition is given to the optimization of the magnetic design and resulting technical considerations for solutions of field tunability and correction, thermal operational stability and follow-up mechanical realization and measurements of the rare-earth PM-based magnets envisaged for the energy-efficient linear optics and ring performance of BESSYIII, stepping on lessons so-far learned from the BESSYII+ upgrade and RF2.0 projects. In this paper we give an overview of the design progress on the PM-based magnets and of considered options for the required higher-order magnet families such as resistive sextupoles and octupoles.

Speaker: Jens Voelker (Helmholtz-Zentrum Berlin für Materialien und Energie)

MOP7162_edited_version.pdf

16:00 Defect Engineering of Transition Metal Oxide Films Employing Low Energy Ion Accelerator for Emerging Non-Volatile Memory Application

Accelerator-enabled ion irradiation is a versatile technique for tailoring the structural and electrical properties of materials. By enabling precise defect creation over targeted regions, ion beams provide an effective way for advancing oxide-based electronic devices. This capability is crucial for emerging memory technologies like Resistive Random Access Memory (RRAM), where defect configuration critically governs resistive switching behavior in metal/insulator/metal structures.
In this work, we investigate the impact of low-energy Ag and Kr ion irradiation on titanium oxide (TiOx) and tantalum oxide (TaOx) thin films used in RRAM devices. The oxide films are fabricated at room temperature employing RF magneton sputtering technique. The 50 keV Ag ion irradiation (fluences: 1×10¹⁵, 3×10¹⁵, 1×10¹⁶ ions/cm²) was performed at HZDR, Dresden, Germany, while the 100 keV Kr ion irradiation (fluences: 3×10¹⁵, 1×10¹⁶, 3×10¹⁶ ions/cm²) was carried out using an ECR-based low-energy particle accelerator at IUAC, New Delhi. The result shows that pristine TiOx devices, which initially exhibited no switching, demonstrated an enhancement in resistance ratio >100 after irradiation with both Ag and Kr ions. In contrast, the TaOx-based devices undergo excessive defect accumulation. Additionally, accelerator-driven techniques, RBS and resonant RBS, together with synchrotron-based XPS, were utilized to enable comprehensive elemental and chemical analysis.

Speaker: Disha Yadav (University of Petroleum and Energy Studies)

16:00 DEGASSING OF DISTILLED WATER-COOLING CIRCUITS AND ITS EFFECTS COPPER-WALLED STRUCTURES

Cooling circuits running with distilled water to cool copper structures like magnets or cooling plates are vul-nerable to air leaking in. The leaked-in air contains car-bon dioxide that lowers the pH from 7 to acidic condi-tions in distilled water and enables dissolved oxygen to react with the surface of the copper tubing, forming cop-per oxides that can grow and mechanically be displaced to clog in locations where the flowrate is low. The pro-cess also reduces the wall thickness of the tubing, even-tually followed by water leakage. Regular unclogging causes the circuit to be opened more often and therefore accelerating the destructive process. A good solution to this problem comes with a steep price: degassing by re-verse osmosis in every copper cooling circuit as dis-solved oxygen is the main problem.

Speaker: Mr Richard Kan (Paul Scherrer Institute)

MOP7148_edited_version.pdf

16:00 Dependence of muon collider luminosity on ionization cooling performance

A 10 TeV center-of-mass muon collider is a high-energy lepton collider that has the potential to achieve physics reach comparable to significantly larger hadron colliders. The final luminosity depends on the performance of the entire complex, from muon beam production to the collider ring, including the rapid cooling and acceleration stages. Achieving the target luminosity imposes stringent constraints on the ionization cooling and the collider optics, such as extremely small betatron functions at the interaction points, which induce strong chromatic effects that ultimately limit the machine momentum acceptance. To meet the momentum acceptance requirements without significant luminosity loss, one possible strategy is to end the muon cooling stage earlier, since a reduction of the longitudinal emittance can be traded against larger transverse emittances with a shorter cooling system. A study of a common optimization of the ionization cooling and the collider ring design to maximize the luminosity is presented in this work.

Speaker: Marion Vanwelde (European Organization for Nuclear Research)

MOP1025_edited_version.pdf

16:00 Design and cold-test of a S-band spherical pulse compressor for beam-test platform at NSRL

To meet the requirement for high-peak-power S-band microwave pulses at the beam test platform of the National Synchrotron Radiation Laboratory (NSRL), a compact Sband spherical pulse compressor has been designed and fabricated. The compressor employs a dual-polarization mode coupler to excite two orthogonal operating modes in a single spherical resonant cavity, enabling dual-mode energy storage within a compact RF structure.The RF design, prototype fabrication, cold test, and tuning of the compressor are presented in this paper. Simulation results show good impedance matching and the expected power gain at the operating frequency. After tuning, the measured resonant frequency, coupling coefficient, unloaded quality factor, and power gain are 2998.2 MHz,5.64, 99098, and 3.34, respectively, in good agreement with the design values. These results demonstrate the feasibility of the proposed S-band spherical pulse compressor for compact high-peak-power RF applications.

Speaker: Zexin Cao (University of Science and Technology of China)

16:00 Design and Development of the New ISOLDE Beam Dumps at CERN

New beam dumps have been developed for the Isotope mass Separator On-Line facility (ISOLDE) at CERN, as part of the ISOLDE Beam Dump Replacement and Sustainability (IBDRS) project. The new design is engineered to ensure an operational lifetime of 30 years and, as by-product, to accommodate the planned doubling of beam power. The absorber assembly consists of water-cooled slices of cladded CuCr1Zr and pure copper. The cladding consists of an encapsulation of 316LN stainless steel, diffusion bonded to the cuprous core by means of Hot Isostatic Pressing (HIP). The cladded blocks are enclosed within a 316 LN stainless steel vessel, which allows the use of pressurised water to cool the dump.
Extensive Monte Carlo and thermo-mechanical studies were conducted to evaluate temperature and stress distribution under nominal and accidental beam conditions, as well as the fatigue lifetime and cooling requirements. Prototyping of the cladded blocks have been produced successfully. This contribution presents the conceptual design, which employs advanced manufacturing methods to provide a sustainable and robust solution for the future ISOLDE beam dumps.

Speaker: Tristan Calvet (European Organization for Nuclear Research)

MOP7135_edited_version.pdf

16:00 Design and Integration of a Passive Caesium Delivery System for the ISIS RF H⁻ Ion Source

The ISIS Neutron and Muon Source has developed a new RF-driven H⁻ ion source to replace the caesiated Penning source in use since the 1980s. The new source operates without caesium and has achieved extracted beam currents of up to 18 mA. To increase the beam current further toward operational requirements, a passive caesium delivery system using Cs₂CrO₄ dispensers has been designed and integrated into the RF ion source. The system releases caesium by heating a Cs collar with the plasma, while forced-air cooling and thermocouples provide temperature control. This paper describes the design, materials, cooling approach, and manufacturing process used to convert the source to a caesiated configuration. Important design features include caesium distribution, thermal isolation between components, and cooling of the main flange. Future work will focus on commissioning the system and optimising caesium delivery for stable, high-current operation.

Speaker: Mr Sankar Raj Rajendran (ISIS Neutron and Muon Source)

MOP7177_edited_version.pdf

16:00 Design and integration of motion control for the Iut24 in-vacuum undulator at TPS

The In-Vacuum Tapered Undulator (IUT24) was developed for the Phase-III beamline project at the Taiwan Photon Source (TPS). To counteract strong, non-linear magnetic attraction forces while maintaining precise synchronization between magnet arrays, a robust motion control architecture was implemented. This system integrates an EPICS-based supervisory layer with EtherCAT field I/O and BiSS-C absolute linear encoders (50 nm resolution) in a closed-loop pulse command configuration. Experimental results demonstrate that during dynamic gap transitions, the tracking error is strictly maintained within ± 2.5 𝜇m, and inter-axial synchronization remains within 0.5 𝜇m. Furthermore, long-term position stability was measured at ±150 nm over 200 minutes. This paper details the hardware integration, advanced motion control strategies, and comprehensive performance evaluations that confirm the system’s readiness for high-precision beamline operations.

Speaker: Chunyi Wu (National Synchrotron Radiation Research Center)

MOP6660_edited_version.pdf

16:00 Design and manufacturing of the next generation of CERN’s North Area Splitter Collimators (TCSC)

CERN’s Transfer Tunnel 20 (TT20) connects the Super Proton Synchrotron (SPS) to three primary targets in the North Area which provide secondary particles to experiments further downstream. Two splitter collimators (TCSC) are installed along this line, each protecting their respective downstream Lambertson septum magnets, which distribute the slow-extracted 400 GeV/c proton beams among the targets. During Long Shutdown 3 (LS3, 2026–2029), two redesigned TCSCs will be installed to improve cooling efficiency, mechanical robustness, and maintainability in the context of the North Area Consolidation (NA CONS) project. The new design also incorporates additional radiation shielding to reduce dose rates in the surrounding area and minimise personnel exposure during tunnel interventions. This contribution presents the main design improvements, thermo-mechanical analyses, and manufacturing developments implemented to enhance the reliability, radiation safety, and thermal performance of the TT20 splitter collimators.

Speaker: Thibaut Parmentier (European Organization for Nuclear Research)

MOP1116_edited_version.pdf

16:00 Design and Multiphysics analysis of β=0.18 half-wave resonator for IFMIF-DONES accelerator

The IFMIF-DONES facility will irradiate and characterize materials to be used in fusion reactors using a neutron flux produced by the interaction of a deuteron beam with a liquid lithium target. A superconducting RF linac will accelerate the beam to the final energy of 40 MeV through two series of superconducting half-wave resonators operating at 175 MHz. The study of a new design for the second family of 27 cavities (optimized for β = 0.18) has been recently presented by INFN, to optimize it from the point of view of production, while maintaining its performance close to what was observed at the first CEA prototype. This paper describes the electromagnetic and mechanical design of the β = 0.18 HWR, conducted in a Multiphysics approach of the cavity optimization. The contributions of pressure, tuners, Lorentz’s force, thermal expansion, construction techniques are analysed up to meet physical and mechanical requirements.

Speaker: Francesco Grespan (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro)

MOP7031_edited_version.pdf

16:00 Design and operation of SLS2 thin septum

In the SLS2.0 upgrade project at the Paul Scherrer Institute (PSI) the injector complex remained mostly unchanged, but we had to design three new storage ring injection elements: the thick septum, the thin septum and beam dump system. Because of the limited dynamic aperture of the upgraded machine, 1 mm septum wall thickness was necessary. To limit stored beam disturbance to 10% of the beam sigma, extremely low (<8 μT) leakage field was required. To achieved this, we used a “sandwich” septum consisting of a copper sheet and a layer of soft magnetic material. In this way we achieved very good screening of the main field.
To power the thin septum, we designed a pulse generator based on a two-stage fast thyristors switch and a matrix capacitor. The latter was built using multiple commercially available ceramic SMD capacitors to avoid the risk of catastrophic failure of the oil filled foil capacitors. We successfully built and commissioned the thin septum and, it works reliably.
In this paper, we present design and operational results of the pulsed thin septum, including simulations and measured results of the main and leakage field. Beam based leakage field evaluation is described as well.

Speaker: Sladana Dordevic (Paul Scherrer Institute)

MOP7131_edited_version.pdf

16:00 Design and Optimization of 2 GHz Traveling-Wave Structures for the CLIC Main Beam Injector Linacs

The design of the CLIC main beam injector linacs requires high-gradient, traveling-wave accelerating structures capable of handling substantial beam-loading effects due to high beam currents. In this work, we present a comprehensive design and optimization study of 2 GHz traveling-wave structures for the electron and positron linacs, which accelerate beams up to 2.8 GeV with a nominal bunch charge of 1 nC, and the booster linac, reaching 9 GeV with a 0.83 nC bunch charge. Each bunch train consists of 352 bunches, necessitating careful management of beam dynamics and wakefield effects.

Using analytical modeling and extensive parameter scans, we optimized the iris geometry to enhance shunt impedance, reduce surface electric fields, and suppress long-range wakefields through detuning strategies. Beam-loading effects were analyzed, and compensation techniques were implemented to minimize bunch-to-bunch energy spread, ensuring stable and efficient acceleration.

This study advances the development of high-performance linac structures capable of operating with high beam currents, supporting the reliable achievement of CLIC performance goals.

Speaker: Adnan Kurtulus (European Organization for Nuclear Research)

MOP7014_edited_version.pdf

16:00 Design and testing of a universal embedded feedback controller for RF cavities

The design of low-level feedback (LLRF) controllers used to stabilize the amplitude and phase of the field inside the RF cavities is typically customized, depending on the frequency and mode of operation. IUAC, New Delhi, India, operates accelerators with RF structures in the range of 12.125-97 MHz, in both normal and superconducting modes. Currently, all the LLRF controllers that have been operational for many years are structure-specific and designed in the analog electronics domain. Component ageing, obsolescence, and limited availability have made it challenging to maintain them due to frequent failures. To overcome this, a universal digital controller has been developed whose design is based on the philosophy of using the same hardware for all the RF structures at IUAC. It is a compact, reconfigurable, and standalone device featuring a microcontroller programmed fractional Phase Locked Loop multiplier for generating various LO signals and system clocks, a wideband analog front end for up/down conversion and signal conditioning, and a System-on-Chip FPGA-based digital board with fast ADCs and DACs, all controlled using an EPICS IOC. The controller is designed as a Sawtooth Waveform Generator for the multi-harmonic buncher, a generator-driven, and a self-excited loop-based LLRF for various RF cavities at IUAC. It operates within acceptable limits of 1% RMS variation in amplitude & a ±1-degree variation in phase. Design details & test results will be discussed in the paper.

Speaker: Mr Ashish Sharma (Indian Institute of Technology Delhi)

MOP6698_edited_version.pdf

16:00 Design challenges and solutions for flat optics in HL-LHC

The High-Luminosity LHC (HL-LHC) upgrade imposes stringent requirements on optics design and correction to achieve its performance goals while maintaining beam stability, sufficient aperture margins, and controlled sensitivity to alignment and field imperfections. Among the explored configurations, flat optics—featuring asymmetric $\beta$-functions at the interaction points—has been proposed as an alternative to the conventional round-optics scheme, particularly in scenarios where crab cavities are not fully deployed. This configuration can be implemented early in the squeeze cycle and offers several advantages, such as reduced impedance, a modified beam–beam interaction pattern, and potential performance improvements. Focusing on the optics at the end of luminosity leveling for the HL-LHC version 1.9, this paper discusses the main design challenges to be addressed—such as improving dynamic aperture while satisfying phase-advance constraints for machine protection—and presents the achieved flat-optics configurations together with their key figures of merit. Research supported by the HL-LHC project.

Speaker: Joshua Gray (European Organization for Nuclear Research)

MOP1067_edited_version.pdf

16:00 Design of a C-band compact phase shifter for particle accelerators

A phase shifter is a key component to tune the phase of RF power for accelerating or deflecting structures in linear accelerators (linacs). This paper presents the design of a compact C-band variable phase shifter for our high-power test platform. It consists of a dual-polarization mode coupler and a movable short-circuited piston for adjusting RF phases. In order to isolate the coaxial port formed by the movable piston and the pipe a choke is introduced inside the piston. Through optimizations, the RF phase variation is simulated to be 10.1233°/mm of piston moving distance.

Speaker: Yelong Wei (University of Science and Technology of China)

MOP7602_edited_version.pdf

16:00 Design of a laser-based emittance meter for the H- beam at CSNS

Following the successful profile measurement of an 80 MeV negative hydrogen (H⁻) beam using a laser wire monitor at the China Spallation Neutron Source(CSNS), an emittance measurement system with a Low-Gain Avalanche Diode (LGAD) sensor has been developed and is currently under commissioning this year. This system utilizes the LGAD to reconstruct the spatial distribution of neutral hydrogen atoms (H0) generated through laser photodetachment. By combining this distribution with laser wire position, it enables complete phase-space reconstruction and accurate emittance measurement of the H⁻ beam. This paper focuses on the design and characterization of the LGAD-based H0 distribution measurement system, including H0 energy deposition simulation, LGAD sensor performance characterization, the design of a ceramic PCB readout board, and local signal response tests. The proposed system offers a promising non-interceptive, high-precision solution for negative hydrogen beam emittance measurement.

Speaker: Muhammad Abdul Rehman (Institute of High Energy Physics)

MOP6620_edited_version.pdf

16:00 Design of an RF-gridded gun for a high-efficiency tristron

The RF gridded gun is a key component of the RF power sources chosen for the FCC-ee tristron. It enables the generation of bunched electron beams via the application of an RF voltage across the cathode-grid gap. The tristron allows a compact tube architecture and provides high RF power production efficiency. The emitted, grid intercepted, and transmitted beam currents are governed by the applied RF grid voltage and DC cathode voltage, providing additional degrees of freedom for controlling the bunch formation. For continuous wave tristron operation at an RF power level of 0.5 MW in the UHF band, particular attention must be paid to several critical design aspects, including beam grid interception, beam optics design, thermomechanical effects, and stress. These factors strongly influence the operational stability, device lifetime, and overall performance. The current status of the RF gridded gun design for the tristron is reported

Speaker: Aditya Singh Thakur (European Organization for Nuclear Research)

MOP7192_edited_version.pdf

16:00 Design of ionization profile monitors at the Integrable Optics Test Accelerator (IOTA) Facility at Fermilab

The Integrable Optics Test Accelerator (IOTA) at Fermilab is transitioning from an electron beam facility to a proton beam facility for studies in nonlinear accelerator optics and space-charge dominated proton beams. This project involves the commissioning and fabrication of Ionization Profile Monitors (IPMs) to enable beam profile measurements at IOTA. In general, IPMs work on principle of residual gas ionization by the beam to generate beam profile. This work focuses on a mechanical design that leverages a controlled injection of noble gases, primarily Argon, as the ultra-high vacuum of the IOTA ring provides insufficient residual gas for ionization. Efforts to understand vacuum integration to ensure compatibility with the storage ring environment, the integration of real-time data acquisition systems and the commissioning of the IPMs will be discussed. This project provides a versatile diagnostic tool, supporting IOTA’s role as a testbed for larger-scale accelerator facilities and contributing to the broader understanding of beam physics in high-intensity, high-space-charge regimes.

Speaker: Matilda Mwaniki (Illinois Institute of Technology)

MOP6357_edited_version.pdf

16:00 Design of pion transport from the ESSnuSB+ target to the LEnuSTORM ring

Measurements of neutrino oscillations in low-energy regimes will require precise knowledge of neutrino-nucleus interaction cross sections for low-energy neutrinos. The ESSnuSB+ project aims to fill the gap in the interaction cross section data by creating a well-quantified neutrino beam from the circulation of stored muons in a low-energy racetrack decay ring, LEnuSTORM. To produce the circulating muon beam, a pion beam will be generated via the impingement of a 1.25 MW proton pulse on a target. The pions must then be focused, transported, and injected to the production straight of the decay ring wherein the pions will decay to muons. 

This contribution discusses the transport of the pions from the megawatt-class target station to their injection in the ring, and considerations for maximizing the muon yield – including momentum selection, maximization of acceptance, and designing a line with minimal path length to increase pion survival whilst accommodating optics matching and layout constraints.

Speaker: Ilias Efthymiopoulos (European Organization for Nuclear Research)

MOP1043_edited_version.pdf

16:00 Design of the high-speed, high-precision average beam current and lifetime measurement system

This paper presents a high-speed, high-precision sys-tem for measuring average beam current and lifetime, addressing the low data refresh rates of existing systems that fail to capture rapid beam dynamics. A comprehen-sive performance analysis identifies key error sources, including the beam probe, data acquisition card, elec-tromagnetic interference, and quantization noise. Exper-imental validation at the HLS shows that with a 0.5 μA resolution probe, the system achieves measurement ac-curacy better than 1 μA at a 1 Hz update rate and 2 μA at 100 Hz. This high-speed, high-precision current meas-urement enables rapid and accurate lifetime determina-tion. The system provides a critical tool for real-time monitoring of injection efficiency and beam stability, and offers essential data support for analyzing beam loss mechanisms and beam dynamics.

Speaker: Xing Yang (University of Science and Technology of China)

MOP6635_edited_version.pdf

16:00 Design overview and project status of the PM gradient dipole at MAX IV

As part of the RF2.0 project*, a permanent-magnet (PM) gradient dipole has been designed at MAX IV Laboratory to replicate the performance of a conventional electromagnet gradient dipole in Unit Cell-1 of the MAX IV 3.0 GeV storage ring. The new PM gradient dipole follows a modular design and utilizes NdFeB permanent-magnet blocks. The main advantage of this design is an expected reduction of up to 42% in the power consumption of the ring’s magnet system, assuming replacement of all dipoles. Moreover, the use of PMs enables a more compact dipole magnet, potentially freeing space within the existing Unit Cell footprints for the integration of higher-performance multipole magnets anticipated for the MAX 4U upgrade. This report summarizes the electromagnetic and mechanical design, installation planning, and the overall project status.

Speaker: Aashoo Sharma (MAX IV Laboratory)

MOP7164_edited_version.pdf

16:00 Design Updates for the Phase-Diversity Electro-Optic Sampling Experiment Using an EEX-Generated Longitudinally Shaped Beam at the Argonne Wakefield Accelerator

Phase-Diversity Electro-Optic Sampling (DEOS) is an attractive non-destructive diagnostic for measuring the longitudinal current profile of relativistic electron bunches. It is particularly suited for characterizing a wide range of temporal durations. This method supports acquisition windows exceeding 10 ps for long bunches while preserving sensitivity to sub-picosecond structures. We are preparing an experiment to evaluate the capabilities of DEOS. We present an updated design that incorporates improved probe-beam synchronization and enhanced optical transport and dispersion management. The implementation of tailored longitudinal current profiles using the EEX beamline is discussed, along with the data-acquisition and reconstruction algorithms used for spectral-encoding retrieval.

Speaker: Alexander Ody (Argonne National Laboratory)

16:00 Design validation and alignment assesment of the girder prototypes for the ALBA II storage ring

The ALBA Synchrotron upgrade into the diffraction-limited ALBA II storage ring is currently in progress and scheduled for completion before the decade’s end. Delivering a twenty-fold reduction in emittance implies a new multibend-achromat lattice with more than twice the current number of magnets. Although the existing tunnel and infrastructure will be reused, a new girder system is required that copes with the high demanding requirements on magnets stability and position tolerances, ranging 10-50 µm between adjacent magnets, and allows magnets re-alignment to compensate long-term slab deformations. To validate the vibrational stability and alignment strategies under realistic conditions, two full-scale girder prototypes have been constructed and installed in a dedicated mock-up area. The prototypes consist of two different frames installed on identical steel plinths, along with an additional granite plinth for compare the performance of this material and specific construction method. The prototypes include a set of dummy magnets, with different supports and alignment mechanisms. A comprehensive measurement campaign has been conducted to evaluate vibrational stability, alignment reproducibility, tolerances deviations during transportation and overall integration workflow. The results provide direct comparison between different girder configurations and quantify the performance of the various alignment systems, being an essential input for finalizing the ALBA II girder design.

Speaker: Nahikari Gonzalez (ALBA Synchrotron (Spain))

16:00 Design, Manufacturing and Testing by SIGMAPHI of the new P2 superconducting intended for the P2 experimental facility at the upcoming MESA accelerator in Mainz

The P2 experiment aims for a high precision measurement of the parity violating asymmetry in the elastic scattering of polarized electrons off unpolarized nuclei. The expected data will be interpreted as a determination of the weak mixing angle, one of the fundamental parameters of the Standard Model, with a precision competitive with measurements at LEP or LHC. The experiment includes a large superconducting solenoid magnet with a free aperture of 2.4 meters and magnetic field of 0.8 Tesla for a total weight of 20 tons.
The superconducting magnetic system including the cryostat, cryogenic service turret, power supplies and quench protection was built by SIGMAPHI and delivered to Johannes Gutenberg University of Mainz in November 2024. The paper presents the design, manufacturing and testing of the superconducting magnet.

Speaker: Frédérick FOREST (SIGMAPHI)

16:00 Design, Manufacturing and Testing of the two superconducting SUPERBEND magnets for the upgrade of the Swiss Light Source (SLS) facility at the Paul Sherer Institute (PSI)

The upgrade of the Swiss SLS towards the SLS 2.0 ring belongs to the worldwide major upgrade/new construction programs to increase the ring performance by approximately two orders of magnitude. At two locations along the ring, the 1.35 T permanent bending magnets will be replaced by superconducting bending magnets (named SUPERBEND)) with a peak field up to 5 T. The two SUPERBEND magnets were built by SIGMAPHI and delivered to PSI in November and December 2025. The paper presents the design, manufacturing and testing of the superconducting magnets.

Speakers: Frédérick FOREST (SIGMAPHI), Raphael PASQUET (SIGMAPHI)

16:00 Design, Manufacturing and Testing by SIGMAPHI of the Pulsed Septa Magnets for the Booster To Accumulator Transfer Line Septa magnets in construction at Lawrence Berkeley National Laboratory (LBNL) for the Advanced Light Source Upgrade project (ALS-U)

Advanced Light Source Upgrade project (ALS-U) is an upgrade project to the LBNL Advanced Light Source (ALS). The ALS is a 1.9 GeV storage ring operating at 500 mA of beam current. It is optimized to produce intense beams of soft x-rays, which offer spectroscopic contrast, nanometer-scale resolution, and broad temporal sensitivity. A new pulsed septum magnet system is required to build a Booster to Accumulator (BTA) transfer line. The system is made of the combination of a Thin septum which deliver a magnetic field of 0.4 T with a half sine pulse duration of 40 µs and a Thick septum which deliver a magnetic field of 1.378 with a half sine pulse duration of 100 µs. The leakage field seen by the circulating beam is lower than 64µTm (40 ppm of the integrated field) and the magnets are operated in Ultra High Vacuum below 5.10-9 torr.
The paper presents the design, manufacturing and testing of the septa magnets built by SIGMAPHI on the behalf of LBNL and delivered late 2025 to ALS-U.

Speaker: Frédérick FOREST (SIGMAPHI)

16:00 Design, Manufacturing and Testing by SIGMAPHI of the superconducting coils for the cyclotron C400 IONS of Normandy Hadrontherapy

The C400 IONS developed by Normandy Hadron Therapy and IBA is an isochronous superconducting cyclotron for cancer therapy which can deliver high intensity of alphas to carbons at 400 Mev/amu and protons at 260 MeV. A set of 4 large superconducting coils embedded in a single cryostat for a total weight of 30 tons and outer diameter 4.7 meters is combined with a magnetic steel yoke of 750 tons to deliver the magnetic field up to 4.2 Tesla. The coils are made with NbTi superconducting wire and cooled at 4.2 K in a zero boil off liquid helium bath cooled by 6 cryocoolers. The coils system includes 2 power supplies of 1100 A and 100 A with their related quench protection and dump resistors. The superconducting coils system including the cryostat, cryogenic service turret, power supplies and quench protection was built by SIGMAPHI and delivered to NHA in April 2025. The paper presents the design, manufacturing and testing of these outstanding superconducting coils.

Speaker: Frédérick FOREST (SIGMAPHI)

16:00 Design, prototyping and production of the vacuum assembly for eXperiments (VAX) for HL-LHC

For the High-Luminosity LHC (HL-LHC), the Vacuum Assembly for eXperiments (VAX) of the ATLAS and CMS experiments required a major redesign to improve accessibility and reduce personnel exposure to radiation during its exploitation and maintenance. In the current LHC configuration, the VAX is located at a closed end of the tunnel, where the risk of oxygen-deficiency is also present. To address these safety concerns, the VAX modules have been relocated to the opposite side of the TAXS absorber, within the experimental cavern. This new layout enables fully remote installation, connection and removal of the VAX modules using a robot suspended from a crane, in line with ALARA (As Low As Reasonably Achievable) radiation exposure principles. It also allows the first quadrupole magnet to be positioned 833 mm closer to the interaction point, improving the final focusing of the beams before collisions.
This paper presents the design, prototyping, and production of the VAX, with a focus on the development of a key vacuum component: the DN80 universal joint bellows. Given the novel application of thin-film coatings to these elements, in particular the use of amorphous carbon (a-C), an emphasis is placed on the coating qualification.

Speaker: Edward Barnes (European Organization for Nuclear Research)

MOP1056_edited_version.pdf

16:00 Deterministic methods and bayesian optimization algorithms applied to the UH Mānoa linac

The University of Hawai‘I at Mānoa (UHM) linac delivers up to 45 MeV electron beams to a Free-Electron Laser(FEL) oscillator.
As the linac is being recommissioned for renewed FEL operation, we are developing simulation and optimization tools to recover operational settings and to explore the landscape of beam-manipulation techniques for future experimental apparatus.
This paper benchmarks classical deterministic methods and Bayesian optimization (BO) algorithms on three representative beam-optics tuning scenarios using a beam dynamics simulation model developed inhouse.
For problems with only a few free parameters, classical methods converge reliably, while finite-difference derivative information improves the performance of constrained
gradient-based solvers.
For the higher-dimensional case, BO with a Gaussian Process (GP) surrogate and SOBOL initialization provides a more robust path toward convergence.
The emphasis is on the number of optimization iterations required for each scenario, in order to anticipate the computational cost of applying the same workflow to higher-fidelity models.

Speaker: Niels Bidault (University of Hawaiʻi at Mānoa)

MOP6318_edited_version.pdf

16:00 Development and characterization of the Double Dipole Kicker prototype at ALBA

The Double Dipole Kicker (DDK) topology has been designed to perform off-axis injection into the ALBA II storage ring, currently under design. The DDK creates a multipole magnetic field by summing two opposite dipo-lar fields generated by four inner and four outer conduc-tor rods. The two dipolar fields are powered by two inde-pendent pulsed power supplies that deliver identical pulses of up to 3 kA and 1.75 s. The rods are precisely positioned along in-air ceramic grooves, to maximize the kick of the injected beam coming from the booster syn-chrotron and, to minimize the field at the stored beam position during top-up injections. A pure dipolar mode is also available when the inner rods are not powered, which it will be used during ALBA II commissioning. The in-vacuum ceramic chamber is coated with a titani-um layer of a variable thickness with the aim of minimiz-ing the effect of induced eddy currents on the stored beam. A DDK prototype has been built and installed alongside the four kickers that generate the injection bump at the ALBA storage ring. First injection tests with the DDK are presented.

Speaker: Francis Perez (ALBA Synchrotron (Spain))

16:00 Development and fabrication of a CW copper injector For SRF industrial cryomodules

Compact SRF industrial linacs can deliver beam powers exceeding 500 kW within the 10 MeV regulatory limit that is difficult to achieve with normal-conducting linacs in a constrained footprint. Although SRF technology was historically too costly and complex for widespread industrial deployment, the advent of conduction cooling has enabled compact, stand-alone SRF systems suitable for both industrial and research applications. However, the limited cooling capacity imposes stringent requirements on beam parameters, including essentially zero beam loss on the SRF cavity walls. This, in turn, demands precise control of the injected beam energy and, critically, high-quality bunching with negligible inter-bunch particles. In collaboration with Fermilab, we developed a CW normal-conducting RF injector featuring a gridded RF gun integrated with the first cell of a copper booster cavity to meet these requirements. This paper presents the complete development of the booster cavity, covering beam dynamics optimization, RF and thermomechanical design, engineering implementation, fabrication, and bench measurement.

Speaker: Chunguang Jing (Euclid Techlabs (United States))

MOP8301_edited_version.pdf

16:00 Development and first beam observations of an Ultra-Fast Bunch-by-Bunch X-ray beam size monitor at SuperKEKB

SuperKEKB is an electron–positron collider that aims to exceed its own world-record instantaneous luminosity by an order of magnitude. During high-current collision operation, various beam instabilities—such as sudden beam loss, electron-cloud effects, and fast-ion instability—can limit beam performance and stable machine operation. To better understand these phenomena, fast diagnostic systems capable of resolving the behavior of individual bunches within a bunch train are essential. To address this need, we have developed a new bunch-by-bunch X-ray beam size monitor. Synchrotron radiation emitted from a bending magnet is passed through a coded-aperture optical element and imaged onto a silicon strip detector. High-speed sampling of the detector signals enables vertical beam size measurements for every bunch in the SuperKEKB main ring with a temporal spacing of approximately 4 ns. This presentation reports an overview of the monitor development, results from initial performance testing and commissioning, and the first beam observations obtained using this diagnostic system.

Speaker: Riku Nomaru (The University of Tokyo, High Energy Accelerator Research Organization)

MOV6603_edited_version.pdf

16:00 Development and preliminary testing of a digital feedback system

This paper introduces the development and preliminary testing of a digital bunch-by-bunch feedback system designed to suppress beam oscillations. Coupled-bunch instabilities, which arise under high-current and multi-bunch operation modes, can induce beam oscillations that significantly degrade collision luminosity and reduce beam lifetime. These instabilities necessitate active feedback suppression. Based on a field-programmable gate array (FPGA) as the core processor, this work independently designed a finite impulse response (FIR) digital filter suitable for transverse feedback and developed the corresponding signal processing electronics. Each functional module of the electronics was tested, with results aligning with design expectations. Furthermore, a comparative analysis was conducted between two filter design methods—the time-domain least squares method and the selective filter method—to determine the optimal algorithm and parameters.

Speaker: liang xu (Institute of High Energy Physics, Chinese Academy of Sciences)

16:00 Development of a Bunch-by-Bunch BPM measurement system at SSRF based on machine learning

Real-time bunch-by-bunch monitoring of transverse position and longitudinal phase has become increasingly important for the stable operation of storage ring light sources and for accelerator physics studies. This paper presents a real-time three-dimensional bunch-by-bunch position measurement system based on machine learning. The system eliminates the need for sampling delay adjustment and avoids complex front-end circuitry by directly digitizing BPM electrode signals with high-speed ADCs at a sampling rate of five times the storage ring RF frequency. By deploying neural network models within the FPGA, the system simultaneously achieves real-time measurement of the transverse position and longitudinal phase with low latency. Beam experiments were conducted at Shanghai Synchrotron Radiation Facility (SSRF) to validate the system’s phase measurement capability. The results demonstrate a bunch-by-bunch phase resolution of 0.4ps while maintaining a measurement latency within 1µs.

Speaker: Jialan Pan (Shanghai Institute of Applied Physics)

MOP6641_edited_version.pdf

16:00 Development of a guanella-type 4:1 impedance transformer for the future SIS100 broadband cavity systems

The SIS100 heavy-ion synchrotron under construction at GSI/FAIR will contain a total of 4 broadband cavities for barrier bucket and longitudinal feedback operation. These need to generate non-harmonic gap voltages with relevant spectral components in a range from 100 kHz to 15 MHz. Previous analyses showed that the input capacitance of the tetrode amplifier limits the cavity’s upper cutoff frequency. To counteract this effect, the load impedance at the input of the tetrode amplifier shall be reduced from 50 ohms to 12.5 ohms at the expense of more driver amplifier power. In this case, achieving an impedance matching to the driver amplifier necessitates the inclusion of a transformer generating a broadband 4:1 impedance transformation over the entire relevant frequency range. A Guanella-type 4:1 ferrite transmission line transformer meeting these requirements was developed, built, and verified by measurement.

Speaker: Christoph Julien Wegmann (Technical University of Darmstadt)

MOP7152_edited_version.pdf

16:00 Development of a Harmonised Framework for Electrical Safety Compliance at CERN

Electrical safety has been identified as one of the main risks in large research infrastructures. At CERN, new regulations for electrical safety are being reviewed to align with current best practices and harmonise the approach. Among other aspects, it covers the compliance of electrical equipment and installations before they are put into operation, to further reduce the risk of accidents, to save time and cost by simplifying design processes, and to standardise the application of the legal requirements. While the new regulations were developed for CERN, they offer a model that can be applied to other research infrastructures. This paper describes the harmonised framework that was implemented to provide a practical guide for applying electrical compliance in the context of a research infrastructure. It was developed based on an analysis of best practices, validated through application to current CERN installations, and verified by industry experts. The framework optimises organisational efficiency by promoting ‘right-first-time’ compliance through a guided quality process. This work is part of the CERN Electrical Safety Project, an initiative established within CERN's Accelerator and Technologies sector to take proactive steps to further mitigate electrical risks, prevent recurrence, and build an even stronger safety culture.

Speaker: Rui Simpson (European Organization for Nuclear Research)

MOP7191_edited_version.pdf

16:00 Development of a high-temperature electron beam test stand for thermal studies of the TATTOOS target at PSI

The Targeted Alpha Tumor Therapy and Other Oncological Solutions (TATTOOS) facility at the Paul Scherrer Institute (PSI) will address the growing demand for medically relevant radionuclides using proton-induced spallation at the PSI High Intensity Proton Accelerator (HIPA). The target is designed to operate with a 100 microA - 590 MeV proton beam at up to 2400 °C for 2–5 weeks. To study thermal mechanisms critical to target performance, a high-temperature test stand was developed based on PSI’s 60 keV, 100 mA electron beam welding machine. This setup allows heating tantalum foils in vacuum to melting temperatures while investigating thermal shock response, emissivity enhancement techniques, and temperature distributions using a Gaussian beam profile with wobbling frequency up to 1000 Hz.
We will present here the static and wobbled beam profiles measurement using a 50 μm tungsten wire scanner moving up to 60 mm/s, with thermionic emission suppressed via voltage biasing. Then, FLUKA and CASINO simulations will show the penetration and scattering differences between the 590 MeV proton and 60 keV electron beams. Finally, temperature measurement for various rotation radii will be presented. Despite differing heating mechanisms, the resulting thermal behavior is directly comparable, supporting target design under realistic operating conditions.

Speaker: Rémi Martinie (Paul Scherrer Institute)

MOP7141_edited_version.pdf

16:00 Development of a low-level RF system for the Sirius passive 3rd-harmonic cavity based on MTCA.4 platform

The SIRIUS storage ring RF system currently operates with two 500 MHz superconducting cavities, each powered by a 130 kW RF plant composed of two solid-state amplifiers (SSA) and a 200 mA beam current. A passive 2-cell superconducting 3rd-harmonic cavity (3HC) is planned for installation in 2027 to increase beam lifetime through bunch lengthening and allow the beam current to be increased to the nominal value of 350 mA. This paper presents the current status of the development of a Low Level RF (LLRF) system for the 3HC based on MTCA.4 platform. The system includes a dedicated analog front-end for RF signal acquisition and conditioning, as well as clock and local oscillator (LO) generation. The digital hardware is based on Struck MTCA modules and an additional digital front-end for external signal isolation and interface with the FPGA GPIOs. Finally, the proposed DSP chain for cavity signal processing and control is presented and discussed.

Speaker: Iago Carvalho de Almeida (Brazilian Center for Research in Energy and Materials)

MOP6385_edited_version.pdf

16:00 Development of a MicroTCA.4-based feedback system for environmental phase compensation of the beam-monitor reference at J-PARC LINAC

In the J-PARC LINAC, the beam monitor and LLRF systems operate with independent RF references. The LLRF system at 312 MHz and 960 MHz incorporates active environmental compensation to enhance stability. However, the 324-MHz beam-monitor RF reference lacks such functionality, resulting in humidity-dependent phase drift. To improve environmental long-term stability, we have developed a feedback-based reference compensation system implemented on a MicroTCA.4 platform. The system takes the 324-MHz beam-monitor reference from the SSA output and down-converts it to 12 MHz on the MicroRTM, enabling IF-phase measurement in the ADCs and fast feedback computation in the FPGA. The feedback-corrected I/Q signals drive the IQ modulator on the MicroRTM to regenerate a stabilized 324-MHz reference, which drives SSA and is redistributed to monitor stations, enabling real-time compensation of environmental phase drift with minimal additional hardware. The system is integrated into the existing LLRF infrastructure at MEBT1, achieving full synchronization, compact installation and cost-effective operation. Long-term studies demonstrated suppression of humidity-induced phase fluctuations and improved reference stability, contributing to enhanced beam-monitor reliability and supporting future high-power beam upgrades at J-PARC. This paper presents the system design, FPGA implementation, and long-term measurements characterizing humidity-induced drift and the stabilized performance with feedback.

Speaker: Yong Liu (High Energy Accelerator Research Organization)

16:00 Development of a PIXE Analysis System Using the MC50 Cyclotron Beamline

Particle Induced X-ray Emission (PIXE) is a non-destructive analytical technique widely used for the precise identification of elemental compositions in materials. This project aims to develop a PIXE system utilizing the MC50 cyclotron beamline, designed to enhance analytical precision and versatility across a broad range of applications. The current infrastructure includes proton and neutron beam irradiation systems, a well-configured beamline, and a vacuum sample holder. A key focus of the development process is the precise control of proton beam energy to optimize elemental excitation and improve analysis accuracy. By tuning the proton energy, the system will provide enhanced detection capabilities for various elements while ensuring minimal interference from background signals. The integration of advanced detector alignment and beamline optimization is expected to enable efficient and reproducible elemental mapping. Once completed, the PIXE system will offer a robust platform for material analysis in areas such as environmental studies, cultural heritage preservation, and advanced material research. This project aims to establish a high-performance PIXE analysis system, advancing the potential of non-destructive elemental characterization for both academic and industrial applications.

Speaker: SangChul Mun (Korea Institute of Radiological and Medical Sciences)

16:00 Development of a real-time waveform monitoring system for pulsed power supplies at Taiwan photon source

A real-time waveform monitoring system has been developed for the pulsed
power supplies in the injection chain of the Taiwan Photon Source (TPS).
The system covers eight kicker and septum magnets spanning the Booster
Ring and Storage Ring injection path. Two operational incidents involving
SR Injection Septum~1 motivated its development: in both cases, waveform
anomalies that were imperceptible by visual inspection led to severe
injection efficiency degradation or complete injection failure. The system
acquires waveforms via EPICS Channel Access, computes shot-averaged
deviations from a stored reference, and compares them against
physics-motivated alarm thresholds derived from dedicated machine study
experiments. The thresholds are expressed as time-resolved curves that
directly map waveform error to injection efficiency degradation. The
system has been deployed and is currently in operation at TPS.

Speaker: Wei-Yu Lin (National Synchrotron Radiation Research Center)

MOP6691_edited_version.pdf

16:00 Development of a simulator for ring accelerator electron beam signals

Beam diagnostic systems are crucial for the Hefei Ad-vanced Light Facility (HALF), a fourth-generation light source under construction. However, the testing of its key devices—such as Digital Beam Position Monitors (DBPMs), the Fast Orbit Feedback (FOFB) system, and Bunch-by-Bunch (BbB) processors—is limited by the lack of a laboratory signal generator capable of simulat-ing accelerator physics, which hinders comprehensive closed-loop testing prior to installation. To address this, we have developed an FPGA-based hardware simulator featuring two input ports for feedback signals and four output ports with independently adjustable signal ampli-tudes and synchronous triggers. It integrates a simplified physics model to generate realistic, wideband beam sig-nals with a pulse width of approximately 5 ns, enabling low-cost, repeatable testing without an actual beam. The system quantizes real bunch signals, simulates trans-verse/longitudinal oscillations in an FPGA, and outputs specific waveforms upon a set trigger. By modelling beam dynamics, it also produces signals closely resem-bling those expected during actual operation in Hefei Light Source (HLS). This simulator assists in designing and optimizing beam feedback algorithms while reduc-ing development difficulty for DBPM and BbB systems. Crucially, it fulfills application needs by enabling previ-ously impossible lab tests—such as evaluating BbB algo-rithms and measuring FOFB latency/bandwidth—before the beam is ready.

Speaker: Xing Yang (University of Science and Technology of China)

MOP6637_edited_version.pdf

16:00 Development of an Integrated UTM and PIXE System with Proton Beam Irradiation for Real-time Material Testing

The integration of real-time mechanical testing with non-destructive elemental analysis under radiation exposure represents a major advancement in characterizing materials in extreme environments. This work focuses on developing an integrated universal testing machine (UTM) and particle-induced X-ray emission (PIXE) system using the MC50 cyclotron beamline, enabling simultaneous evaluation of mechanical behavior and elemental changes during proton irradiation. The current setup includes the proton/neutron irradiation system, beamline configuration, and a vacuum-mounted sample holder. Upcoming steps involve incorporating UTM-based real-time stress–strain monitoring and optimizing PIXE detector alignment for high-resolution elemental profiling. This combined platform will allow concurrent observation of deformation, elemental redistribution, and irradiation-induced effects, reflecting conditions relevant to high-radiation and high-temperature applications. Expected outcomes include establishing direct correlations between mechanical property degradation and compositional changes, offering new insights into radiation damage mechanisms. Ultimately, the integrated UTM–PIXE system is anticipated to set a new standard for advanced material testing and support the design of resilient materials for nuclear, aerospace, and other high-intensity operational environments.

Speaker: Dr Seyoung Oh (Korea Institute of Radiological and Medical Sciences)

16:00 Development of an MTCA.4-based Digital Low-level RF Control Solution for the TLS Linac System

The Linac of Taiwan Light Source (TLS) has operated for over thirty years, necessitating modernization to ensure sustainability operation. A new digital low-level RF (DLLRF) control system has been developed to replace aging components and address the situation of having only a single backup unit. The MTCA.4 platform was adopted for its scalability and high-performance throughput. The system integrates the DACs module for arbitrary waveform generation with external triggering, and a direct-sampling down-converter with the ADCs module for waveform acquisition and advanced real-time diagnostics. The DLLRF interface has been fully integrated into the EPICS framework for seamless compatibility with existing controls. The new system supports I/Q waveform downloads with online amplitude and phase adjustments, and it provides waveform digitization capabilities for monitoring RF signals associated with the klystron modulator. Dedicated graphical applications have been designed and integrated into the current operator interfaces. The MTCA.4-based DLLRF system has been successfully deployed and validated during routine operations. This paper presents the development, implementation, and operational results of the upgraded control system.

Speaker: Chunyi Wu (National Synchrotron Radiation Research Center)

16:00 Development of an MTCA.4-Based High-Speed Data Acquisition System for Gas Monitor Detectors at S3FEL

This report presents the development and validation of a high-speed data acquisition system for Gas Monitor Detectors at the Shenzhen Superconducting Soft X-ray Free-Electron Laser (S3FEL). The system is designed to support real-time, pulse-by-pulse monitoring of photon intensity and beam position across six beamlines operating at up to 1 MHz repetition rate. Based on the MTCA.4 platform, the DAQ integrates custom front-end electronics with an AMC digitizer featuring four-channel 1 GSPS sampling and 14-bit resolution. Key innovations include dual-redundant fiber timing synchronization, PCIe-based real-time data streaming, and EPICS-integrated slow control. Preliminary tests confirm ADC linearity, low timing jitter, and sustained PCIe throughput, demonstrating the system’s readiness for deployment in MHz-class FEL facilities.

Speaker: Zhiyuan Zhang (Institute of Advanced Light Source Facilities, Shenzhen)

MOP6678_edited_version.pdf

16:00 Development of Analog Electronics for the Beam Loss Monitoring System in the Superconducting Section of the CSNS II Linac

The analog electronics for the Beam Loss Monitoring (BLM) system in the superconducting section of CSNS II is mainly used for signal conditioning of the output signals from BLM beam loss detectors. For the BLM electronics of CSNS I, a single-channel transimpedance circuit was designed. The overall response time of the detector, transmission cable, and electronics is approximately 150 μs, with a focus on high-sensitivity design, which fails to meet the 10 μs response time requirement for machine protection in the superconducting section of CSNS II. Referring to the design of the LHC BLM electronics, a Charge-to-Frequency Conversion (CFC) circuit has been developed to split the charge generated by beam loss ionization into cumulative charge packets Qt with a fixed time interval T. Machine Protection System (MPS) triggers are generated by comparing the count from a counter with a calibrated unit-time count, and a high-speed ADC samples the frequency waveform to calculate the beam loss value through algorithms.

Speaker: Renjun Yang (Institute of High Energy Physics)

MOP6627_edited_version.pdf

16:00 Development of non-destructive emittance tuning system utilizing Synchrotron Radiation Monitors

In SuperKEKB, the emittance of the injected beam is an essential parameter that significantly affects the injection rate. In the linac, the beam tail can be kicked depending on the orbit through the accelerating structures, which leads to a degradation of the emittance. Fortunately, these effects can be minimized by appropriately optimizing the beam trajectory. On the other hand, the KEKB Linac uses pulse steering to supply beams to four different rings. However, the number of pulse steering is limited in the upstream part of the Linac, and orbit drift in the upstream part often leads to emittance drift, deteriorating injection rate. To address this issue, we have developed a non-destructive emittance tuning system utilizing Synchrotron Radiation Monitors.

Speaker: Naoko Iida (High Energy Accelerator Research Organization)

MOP6653_edited_version.pdf

16:00 Development of the beam permit system for the RAON accelerator

The Beam Permit System (BPS) has been implemented as a software-level permit and verification layer for the Rare isotope Accelerator complex for ON-line experiments (RAON), a heavy-ion accelerator being commissioned at the Institute for Basic Science (IBS) in Korea. While the Machine Protection System (MPS) provides fast hardware signal-based protection against beam-induced equipment damage, the BPS complements it by checking software-level conditions such as EPICS Input/Output Controller (IOC) availability, Process Variable (PV) consistency, and operating-mode correctness. By combining IOC monitoring, configuration checks, and mode-aware permit logic, the BPS ensures that beam delivery is allowed only when all required operating conditions are satisfied. Commissioning tests in the currently operational RAON section (up to SCL3) show that the BPS identifies hardware or software inconsistencies and inhibits beam extraction when necessary, ensuring that beam delivery occurs only under verified and safe operating conditions. This paper presents the design and implementation of the RAON BPS and summarizes the first commissioning results of this combined hardware–software protection approach.

Speaker: eunsang kwon (Institute for Basic Science)

MOP6670_edited_version.pdf

16:00 Development of undulator assembly optimization at the ESRF

The Insertion Devices and Magnets group at the ESRF is developing new methods and software tools for optimizing undulator assemblies. Measurements of the individual magnet blocks are used to build a model of the undulator, which is updated during assembly and employed for field optimisation and shimming. This software – written in Python and interfaced with magnetic measurement benches – is being tested on Cryogenic Permanent Magnet Undulators (CPMUs). The optimisation methods, the software architecture, and the first measurement results will be presented.

Speaker: Gaël Le Bec (European Synchrotron Radiation Facility)

16:00 Diagnosing ghost bunches with the upstream extinction monitor in the Mu2e experiment

The Mu2e experiment has a stringent requirement for extinction of the pulsed proton beam, referring to the elimination of particles between proton bunches to a relative level of $10^{-10}$, which means a single out-of-time particle in the inter-pulse gaps for every 250 complete proton pulses. As the construction of the Mu2e experiment nears completion, it is crucially important to make an early measurement of the beam extinction in its current condition. Hence the upstream extinction monitor was constructed and operated to probe for problems in the proton pulse structure or a higher than expected incidence rate of out-of-time particles.

The analysis in this work comes from data taken in March 2026. The long data run showed a significant presence of out-of-time particles from ghost bunches in the Delivery Ring approximately 388 ns after the centers of the main proton pulses. These are hypothesized to be the result of a combination of a RF frequency mismatch, particle space charge, and machine impedance during the rebunching sequence in the Recycler Ring, which can lead to particles leaking into adjacent buckets, but further studies and simulations are needed to confirm this.

Speaker: Ryan Hensley (University of California, Davis)

MOP6370_edited_version.pdf

16:00 Diagnosing the longitudinal phase space of an electron beam using a flat dechirper

Diagnosing the longitudinal phase space of electron beams is crucial for characterizing and optimizing FEL performance in X-ray Free Electron Laser (XFEL). Because of GeV level energy and tens of femtosecond duration, diagnosing methods are limited, and the X-band Transverse Deflection Cavity (XTCAV) became a conventional equipment, which employs short RF waves (X-band) to transversely deflect electron beams. However, operation of XTCAV is complex with careful treatment to reduce RF and electron beam jitter, and moreover installation cost is expensive. Other approach to the diagnostics is a kind of passive streaking method implying a corrugated plate, which induces self-generated wakefields resulting in transverse deflection. In this presentation, we introduce a new analyzing method to diagnosing the longitudinal phase space of a corrugated flat dechirper. We demonstrate that the nonlinear correlation issue, a key limitation in conventional dechirper diagnostics, can be numerically addressed by applying the Tikhonov regularization method. The effectiveness of this approach is validated through well-defined simulations. We also show experimental results performed in the PAL-XFEL soft-xray beamline with expectation of FEL power profile.

Speaker: MyungHoon Cho (Pohang Accelerator Laboratory)

16:00 Dielectric characterization of Beam Line Absorber samples for next-generation high intensity electron beam SRF accelerators

PERLE, under construction at IJCLab, is a multi-turn Energy Recovery Linac designed for high intensity electron beams of 10 MW peak power (20 mA, 250 MeV). Simulations of its SRF cryomodule * predict more than 100 W of higher-order-mode (HOM) power per cavity induced by the short bunches, indicating that Beam Line Absorbers (BLAs) at 40 K may be required between cavities to dissipate the HOM power and protect the 2 K stage. However, the lack of complete properties of dielectric materials for candidate absorbers limits accurate BLA design. To address this, we are conducting dedicated studies of BLA materials at IJCLab. We measured the broadband dielectric properties of Kyocera SC1000 samples from BNL ** at room temperature using a setup at CLIC (CERN) and cross-validated the results with independent measurements from JLab***. In parallel, we designed and simulated two cryogenic coaxial test stands, one operating up to 18 GHz and another extending coverage to 40 GHz. These warm measurements provide baseline data for upcoming cryogenic studies and validated input for the design of BLAs in next-generation accelerators such as the EIC at BNL, FCC-ee at CERN, and in particular PERLE at IJCLab.

Speaker: Axel Perez Ruiz (Université Paris-Saclay, CNRS/IN2P3, IJCLab, Accelerators & Cryogenic Systems)

MOP7022_edited_version.pdf

16:00 Digital twin development for the NASA Space Radiation Laboratory

The NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory simulates the galactic cosmic ray space radiation environment by delivering high energy heavy ions and protons to the NSRL Target Room for radiobiology studies and microelectronics testing. The AGS Booster synchrotron delivers beams to the NSRL beamline via resonant slow extraction. NSRL tuning is difficult due to the non-linearity from slow extraction and octupoles, and the beam shape is optimized empirically by operators. To streamline and improve NSRL operations, we develop a real-time digital twin for the NSRL beam line, starting from the extraction bumps in the Booster and extending all the way to the targets. This digital twin allows users to both load live settings from the real system to the online model, and to send model suggested settings to the real machine. We demonstrate that an accurate digital twin can tremendously help improve operations at the NSRL beam line.

Speaker: Kiel Hock (Brookhaven National Laboratory)

MOP6352_edited_version.pdf

16:00 Distributed control of large-scale magnet power supplies in the HALF

The fourth-generation synchrotron radiation source, with its ultra-high brightness and nanometer-level spatial resolution, has become a core facility supporting cutting-edge scientific research. The Hefei Advanced Light Source comprises over 2,000 magnet power supplies, requiring remote online adjustment and synchronized current settings to meet the physical requirements of the electron beam. This paper proposes a distributed control system architecture to address the control requirements of large-scale magnet power supplies. At the hardware level, build server clusters and leverage virtualization technology to deliver highly available system services. At the network level, a star-topology Ethernet network and a synchronized timing network are constructed. At the software level, a customized communication protocol enables remote monitoring of the magnet power supply. Additionally, data security and efficient deployment were also taken into consideration. This distributed control system provides a scalable solution for batch magnet management in fourth-generation light sources.

Speaker: Fang Li (University of Science and Technology of China)

MOP6669_edited_version.pdf

16:00 Effect of FCC-ee collimator impedance on beam stability: design and optimization strategy

Operating at 45.6 GeV with high beam current, low emittances, and long damping times, the FCC-ee low-energy collider configuration is particularly sensitive to collective effects and impedance-induced beam instabilities. Controlling these effects requires a continuously refined impedance model to guide design choices and to establish reliable instability thresholds. Recent studies identify the collimation system as a dominant contributor to the total machine impedance, with geometric effects playing a key role in beam stability.
Within this framework, a flexible, modular, and comprehensive impedance model enables targeted optimization and systematic stability assessments. The total impedance model includes the beam pipe, collimators, RF cavities, bellows, tapers, and beam position monitors.
This work presents the latest FCC-ee impedance model with a full evaluation of collimator impedance, addressing current limitations related to the challenging simulation regime. It provides an in-depth analysis of the contribution of collimators to beam stability, comparing different optics configurations, novel materials, and advanced design solutions, as well as highlighting ongoing progress in impedance modelling, intensity threshold evaluation, and instability mitigation.

Speaker: Dora Gibellieri (European Organization for Nuclear Research, Université de Caen Normandie)

MOP1083_edited_version.pdf

16:00 Efficient Slice Energy Spread Measurement Using Two Screens

The slice energy spread is a critical parameter in free-electron laser (FEL) facilities. A high-brightness injector is typically characterized by a low slice energy spread, which can induce micro-bunching instability and consequently degrade the FEL lasing process. Conventional mitigation involves controlling the slice energy spread using a laser heater, making its precise measurement essential.

Approaches has been proposed based on polynomial fitting after scanning the beam size at different energies or dispersions. However, these approaches are time consuming.

We have developed a simpler method for measuring slice energy spread by employing two screens in dispersion stage. With a proper set of parameters, we can locate the beam waist at the middle of two screens, and get the slice energy spread quickly. This method has been performed at SHINE injector. The measurement was completed in less than one hour, and the result turned out to be 2.3keV, which fits with the simulated value.

This method can greatly improve the efficiency of energy spread measurement, saving time and effort for beam diagnostics.

Speaker: ShengBin Ye (ShanghaiTech University)

16:00 Electro-Magnetic Separator Topology Concept for FCC-ee

The layout of the FCC-ee collider requires the separa-
tion of the electron and positron beams, which are circu-
lating in opposite directions, on either side of the RF sys-
tem. Only one of the two beams must be deflected, while
the other one (the beam circulating in the direction of the
RF) shall remain untouched to avoid synchrotron radiation
being emitted toward the RF section. This functionality
is achieved using a combination of an electric field and a
perpendicular magnetic field, which must be matched to
each other along the entire length of the separator to avoid
synchrotron radiation (SR) emission toward the supercon-
ducting RF cryomodules. In order to satisfy the matching
condition 𝐵 = 𝐸/𝑐 for relativistic particles, an extremely
weak magnetic field (5 mT) is required for a given achiev-
able static electric field (1.5 MV/m). This article presents a
separator concept that combines an under-vacuum electro-
static system with a low-field large-aperture outside-vacuum
dipole magnet to achieve the main separation functionality
while providing excellent field matching and low SR produc-
tion. In addition to the concept development, three critical
aspects have been identified and are the subject of ongoing
studies to assess feasibility by end of 2027: high-voltage
(HV) breakdown, beam coupling impedance and machine
protection.

Speaker: Lucien Porta (European Organization for Nuclear Research)

16:00 Electromagnetic resonance behaviour of LHC vacuum interconnect modules

Beam-induced heating has become increasingly relevant for vacuum interconnect modules with the continuing rise in the LHC beam intensity, thereby heightened their sensitivity to electromagnetic resonances. While the heating itself is not the primary subject of this work, the associated failures have motivated a broader examination of how the different geometries of the vacuum interconnect modules respond to strong beam-induced electromagnetic fields. Various circular and elliptical interconnect RF-finger modules were therefore studied using the standard coaxial-stretched-wire method. The intrinsic resonances of the modules were identified as a function of the variation of module length and controlled misalignment, by means of a new instrument that enables wide geometry variations while keeping the coaxial wire under constant tension.

The measurements reveal clear differences in the resonant spectra of the various designs and show that small geometric deviations can strongly influence mode frequencies and field localisation. Understanding these behaviours is essential as the HL-LHC will operate with even higher bunch intensities, increasing the likelihood that unfavourable resonant conditions could lead to excessive local power deposition. The results contribute to improved assessment and qualification of interconnect modules for future high-luminosity operation and support the design and development of novel interconnect modules for next-generation machines.

Speaker: Patrick Krkotic (European Organization for Nuclear Research)

MOP7112_edited_version.pdf

16:00 Electron Beam Longitudinal Profile Measurements at High Charge in the APS-U Particle Accumulator Ring

With the commissioning and operation of the Advanced Photon Source Upgrade storage ring, higher charge is demanded from the injectors including the particle accumulator ring (PAR). Increased charge leads to a growth in PAR bunch length which can lead to inefficient injection into the booster synchrotron. Reduction in the extracted PAR bunch duration has been observed after modifications including reduced impedance kicker chambers and higher 12th harmonic amplitude rf. Recent PAR charge requirements for storage-ring operations are 5-6 nC per bunch for 216 many-bunch mode at 200 mA and 14-15 nC per bunch for 48-bunch timing mode at 130-140 mA. At these charge levels, extracted RMS bunch durations of 400 ps and 490 ps, respectively have been measured. 20 nC is required for 200-mA timing mode. PAR bunch length has been obtained from a fast light detector diagnostic known as the bunch duration monitor (BDM). We have recommissioned the Hamamatsu C5680 streak camera with a M5677 slow vertical sweep scan unit for comparison with the BDM. Bunch length and calibration data from the streak camera have been obtained and will be discussed as will longitudinal modulations observed in the bunch.

Speaker: Jeffrey Dooling (Argonne National Laboratory)

16:00 Elettra 2.0 magnets and magnetic measurements results

The Elettra 2.0 project involves the installation of 648 new electromagnets for the upgrade of the existing light source [1]. Following the design and prototyping phase, the magnet series are currently being manufactured and delivered to Elettra to be suitably characterized before the installation. To this aim, a new magnetic measurement laboratory has been built and equipped during last year.
The measurements currently being performed at Elettra consists of the magnetic field quality measurement (for acceptance tests), magnetic field excitation curves, the alignment of multipole magnet, and the 3D magnetic field mapping. This article presents the results of the magnetic measurements performed until now.

Speakers: Domenico Caiazza (Elettra-Sincrotrone Trieste S.C.p.A.), Davide Castronovo (Elettra-Sincrotrone Trieste S.C.p.A.)

MOP7061_edited_version.pdf

16:00 Elettra 2.0 – Status of the Removal & Installation activities

On July 2, 2025, at Elettra, we began the “Dark Period” (DP): the definitive shutdown of Elettra's Storage Ring (SR) with its auxiliary equipment and most of its beamlines. During the first phase of the DP, we removed the entire SR lattice structure with its associated cabling, piping, and supports. At the same time, the Service Area (SA), where most of the equipment for operating the SR was and will be located, was emptied to allow for infrastructure work and the subsequent installation of new racks and equipment. “On the other side of the wall,” most of the photon beam lines are being reconfigured, upgraded, or installed, which involves several changes to the configuration of the SR tunnel's outer shielding wall.
The paper describes the status of DP activities, the difficulties encountered, and the mitigation strategies adopted. Logistics plays an important role in this scenario, organizing the handling, transport, storage, and arrival times of materials, equipment, and instrumentation racks. This flow is bidirectional and includes both what is removed and disposed of and the parts to be installed, with a significant coexistence of old and new material.

Speaker: Roberto Visintini (Elettra-Sincrotrone Trieste S.C.p.A.)

MOP7144_edited_version.pdf

16:00 Elettra cavity HOM and dedicated dampers design

The 500 MHZ Elettra type cavity have been implemented in the 3rd generation light source Elettra Synchrotron Light Source since the beginning of its operations. It is a normal conducting, single cell cavity with no High Order Modes (HOM) dedicated dampers. The very same cavity will be used for the new low emittance Elettra 2.0 (E2.0) project. E2.0 will host four independent RF accelerating cavities, each one fed with its own amplifier. A complete investigation of the possible coupled bunch longitudinal and transverse instabilities has been carried out due to the most demanding beam quality requirement together with the installation constrains given by the new vacuum chamber of the E2.0 lay-out with respect to the Elettra storage ring. Results in time domain and frequency domain up to 7 GHz have been double-checked. Some high impedance high frequency longitudinal modes have been identified thanks to his analysis. The feasibility to realize a dedicated dumper for the most dangerous modes that could also fit the available room is also investigated.

Speaker: Nuaman Shafqat (Elettra-Sincrotrone Trieste S.C.p.A.)

MOP7007_edited_version.pdf

16:00 Eliminating mains noise effects in accelerators with Machine Learning

Power supply ripples at various frequencies - characteristic to the magnet circuits or from the electrical network - have always been an issue in accelerator operations, with several mitigation measures put in place over the years. This contribution summarises the efforts in the CERN SPS over the last years to compensate the ripple at 50 Hz and its harmonics in the main quadrupole circuits, using Machine Learning methods. The detrimental effects of the ripple at low energy for LHC-type beams and at top energy for slow extracted beams are introduced. For optimal conditions of slow extracted beams, a continuous control algorithm had to be conceived. The implementation required hardware modifications on the power converter electronics side, additional new controls infrastructure and the development of adaptive algorithms that can deal with changes in the electrical distribution network throughout the day. Continuous control with tailored adaptive Bayesian Optimisation has been implemented for slow extracted spill control throughout 2024 and 2025. The improved spill quality obtained over the years will be discussed. Finally, results from R&D towards one-shot correction algorithms for beams that are only played on-demand (i.e. LHC beams) will also be briefly summarised.

Speaker: Borja Rodriguez Mateos (European Organization for Nuclear Research)

MOP6001_edited_version.pdf

16:00 Emittance growth due to Power Converter Ripple and Noise at 50 Hz harmonics during LHC collisions

Transverse emittance growth can adversely affect the luminosity production performance of colliders such as the Large Hadron Collider (LHC) at CERN. While Intra-Beam Scattering (IBS) and Synchrotron Radiation (SR) effects represent important ingredients for the emittance evolution, measurements in the LHC do not match predictions from these two effects, suggesting the presence of additional emittance growth mechanisms. External excitations, such as power supply ripple and noise at 50 Hz harmonics, are additional sources of emittance growth especially in the presence of non-linearities as induced by beam-beam effects. In the LHC, the most prominent excitations during collisions are harmonics of 50 Hz clustered around 8 kHz. In this work, we quantify the expected contribution of these excitations to the emittance evolution and proton losses using single particle tracking simulations including a realistic excitation spectrum as observed in operation.

Speaker: Anna Radoslavova (European Organization for Nuclear Research, Goethe University Frankfurt)

MOP1005_edited_version.pdf

16:00 Energy Efficiency in the North Experimental Area at CERN

The North Experimental Area at CERN is a versatile experimental facility that provides proton, hadron, electron, muon, and ion beams to over 2000 users annually for detector R&D and fixed-target experiments. Currently, this facility, which is more than 45 years old, is undergoing a consolidation program to enhance availability and reliability and to prepare for new experiments and test beams in the coming decades. In this context, and within the framework of ISO 50001, energy efficiency was assessed, potential energy-saving opportunities were identified, and various strategies for sustainable operation were evaluated. This contribution summarizes the results and outlines planned measures for future implementation.

Speaker: Thomas Zickler (European Organization for Nuclear Research)

MOP7181_edited_version.pdf

16:00 Energy ramps for the high-energy booster of the FCC-ee collider

Beams in FCC-ee are injected from a full-size booster synchrotron, placed on top of the collider in the same tunnel. The booster prepares electron and positron bunch trains alternately for all foreseen beam energies from 45.6 GeV to 182.5 GeV and operation modes such as filling the collider from scratch or top-up. Polarized bunches could furthermore be supplied for the beam energy calibration. The first two operation modes require optimizing the energy ramps and RF voltage programs to achieve the small transverse beam size for injection in the collider while maintaining longitudinal beam stability. Specifically, the ramp for the Z operating point has an energy overshoot to boost the synchrotron radiation damping effect. Beam stability issues at low energy can be mitigated by damping wigglers at the cost of a higher energy spread at extraction. Further optimizations reduce the RF power requirements for all cycles.

Speaker: Lina VALLE (European Organization for Nuclear Research)

MOP1090_edited_version.pdf

16:00 Engineering Design of HTS Solenoids for the 6D Cooling Demonstrator and RF Test Facility for the Muon Collider

The 6D cooling section of a Muon Collider is essential to produce a high-brightness muon beam. To demonstrate the technological feasibility of this system, the IMCC has started a Muon Cooling Demonstrator programme. Within the programme, test stands integrating 3 GHz RF cavities and superconducting solenoids will be developed to test the RF breakdown limit in a 7 T background magnetic field. As key part of the programme, a cooling cell module based on the B5 cell type is currently under study, to validate at engineering scale the integration of a B5-like cooling cell.
The magnets of the test stand and B5-like demonstrator are based on non-insulated high-temperature superconductors (HTS) operating at 20 K. The test stand consists of 250 mm bore split solenoid, generating 7 T field on-axis and gradient of nearly 70 T/m in alternate-polarity mode. It will serve as a proof of technology for the B5-like demonstrator, which consists of two pairs of split solenoids with 370 mm and 570 mm bores, designed to produce a precise magnetic field profile with on-axis field swing of ± 7.3 T, within a compact integration, subject to strong axial forces in the MN range.
In this work, the engineering design of the solenoids of the B5-like demonstrator is presented along with the main design parameters of the RF test facility (RFMFTF v3.2). A focus is given to the technological solutions considered in the design, accounting for the compact magnet layout required for cooling cell integration.

Speaker: Giuseppe Scarantino (Istituto Nazionale di Fisica Nucleare, Laboratori Acceleratori e Superconduttività Applicata, Sapienza University of Rome)

MOP7080_edited_version.pdf

16:00 ESS SCL fast tuning system characterization during LINAC commissioning

In this paper we present the results of European Spallation Source (ESS) Superconducting Linac (SCL) cavities measurements which allowed us to determine crucial parameters for future SCL operation and Low-Level Radio Frequency (LLRF) systems tuning. The campaign of measurements was performed during the SCL commissioning for the second beam on dump campaign and prior to beam on target. All the measurements taken involved the usage of the cavity fast tuning system – the piezo tuner. Additionally, measurements of mechanical modes were done for all cavity types, which allowed to determine their longitudinal natural frequencies and prepare accordingly for optimal piezo tuners usage in the presence of the Lorentz Force Detuning (LFD). To confirm the frequency range of possible LFD, the LFD coefficient has been determined, and to ensure the piezo tuners are able to compensate for it, their characterisation has been carried out. SCL cavities passband modes were measured, in order to fine tune notch filter frequency position for all cavity types (expected pi-mode neighbour position shows, as expected, a natural spread due to small variation in the cavity geometries). Piezo capacitance as function of temperature was measured, which can be used as a fault tuning tool in case of piezo aging effects, causing unexpected cavity detuning at high gradient. The described tools and measurement outcome are presented with their future implementation in the ESS Linac environment.

Speaker: Ms Agnieszka Zwozniak (European Spallation Source)

MOP7040_edited_version.pdf

16:00 ESS SRF cavity preparation for beam on dump 2/beam on target phase

The ESS (European Spallation Source) is presently configured as a 1.3 GeV linac, with three superconducting cavity sections starting from 90 MeV. For the moment in operation, we have 82 superconducting cavities: 26 double spoke resonators (b=0.5), 36 medium and 20 high beta elliptical cavities (respectively b=0.67 and 0.86). In this paper we would like to present the restart of the Linac after 4 months of summer break and further cryomodule installations. During this time all data from previous Beam on Dump (BOD) run at 870 MeV was collected to have a better overview before BOD2/BOT (Beam on Dump 2/ Beam on Target). The Warm Coupler Conditioning (WCC) started in the middle of October 2025. In November 2025 the first cryomodule was tuned and restored to the nominal gradient, after the off-resonant Cold Coupler Conditioning (CCC). During this process the key performance indicators are compared to those obtained during the Site Acceptance Test (SAT) and the 2025 BOD.

Speaker: Ms Agnieszka Zwozniak (European Spallation Source)

MOP7039_edited_version.pdf

16:00 ESSnuSB+: target station studies

The ESSnuSB+ project aims to produce an intense neutrino beam using the high-power proton linac of the European Spallation Source (ESS). A key element of the facility is the target station, where a 2.5 GeV proton beam interacts with a granular titanium-sphere target to generate an intense pion-meson beam. These pions are focused by a magnetic horn and directed toward a storage ring before decaying into the muons that will be stored in the ring while emitting the neutrinos.

In this work, detailed FLUKA simulations are used to model the full chain of particle production and energy deposition across major components of the target station. The simulations quantify the spatial distribution of deposited power and radiation dose. These results are essential for validating the feasibility of the target design, assessing component lifetime, and informing the engineering of cooling and shielding systems.

Furthermore, updated predictions of the pion production are presented, representing the first step in the optimisation of the neutrino production for the ESSnuSB+ experiment. These results contribute to the overall design validation of the facility.

Speakers: Eric Baussan (Institut Pluridisciplinaire Hubert Curien), Julien Hiegel (Centre National de la Recherche Scientifique)

MOP1095_edited_version.pdf

16:00 ETHERNET-ENABLED DATA ACQUISITION AND SUPERVISION SYSTEMS FOR THE HL-LHC QUENCH PROTECTION SYSTEM

Ethernet-enabled Data Acquisition and Supervision (EDAQ) systems have become the standard platform for commissioning, controlling, and supervising the next generation of Quench Protection Systems (QPS) at CERN. EDAQ-equipped QPS devices have been installed in recent upgrades to magnet test facilities, most notably in the IT-String test facility.
This contribution summarizes the operational experience gained during these installations and highlights the key advancements that have enabled the EDAQ ecosystem to mature into a production-ready solution. Notable developments include a configuration validation system, improved error-recovery strategies, over-the-air (OTA) firmware updates, and seamless integration with the full range of HL-LHC QPS equipment.
The results of a comprehensive set of performance tests are presented and discussed, confirming that the EDAQ system is ready for deployment as part of the High Luminosity LHC upgrade, for which the installation is to start in the coming years.

Speaker: Pau Jordan Oliveras Cejas (European Organization for Nuclear Research)

MOP7159_edited_version.pdf

16:00 EURO-LABS: integrating European Research Infrastructures for physical sciences

The European Laboratories for Accelerator Based Sciences (EURO-LABS) programme advances research frontiers by providing unified Transnational Access (TNA) to leading European Research Infrastructures (RIs) in the Physical Sciences. It brings together the nuclear physics, accelerator, and detector R\&D communities to foster collaboration and stimulate synergies. With 33 partners across Europe, EURO-LABS forms an integrated network of RIs ranging from small-scale test facilities to large European Strategy Forum on Research Infrastructures (ESFRI). The access provided enables research at the technological frontiers of accelerator and detector development, supporting the exploration of new physics concepts and opening new avenues in both fundamental and applied research --- from optimizing reactor operation to mimicking stellar reactions.
EURO-LABS actively promotes diversity and inclusion, offering equitable access to researchers across nationalities, genders, ages, and career stages, while strengthening Europe’s collaborative scientific landscape. EURO-LABS started in September 2022 and will conclude in August 2026. This contribution will present highlights of the project’s activities, along with notable experiments and supported research carried out at the participating facilities.

Speaker: Ilias Efthymiopoulos (European Organization for Nuclear Research)

MOP7145_edited_version.pdf

16:00 Evaluating In-Context Learning for Advanced Light Source EPICS Process Variable Prediction

Large language models are becoming increasingly relevant for accelerator operations, where they assist with common tasks like retrieving historical data, preparing analysis scripts, and coordinating multi-step procedures. At the Advanced Light Source (ALS), these operators use their personal jargon (e.g. “sector 4 beam current”) to search for the correct PV name from numerous channels, resulting in countless variations of naming conventions. Strong scores on general-purpose benchmarks do not indicate how well a model maps operator jargon to facility-specific EPICS process variable~(PV) identifiers. Building on the semantic channel-finding benchmark, we evaluate chat-based large language models on two tasks using 101 ALS expert query–PV pairs. The first probes query-level grounding via single-item testing. The assessment is executed with varying inference-time cues, scored by character-wise correspondence (Levenshstein ratio). The second probes structural understanding by requiring the model to infer character-sequence mapping from the global naming-token vocabulary under prescribed edge-count budgets. We report precision, recall, combined retrieval score (F1), and token overlap (Jaccard similarity). Applied to 27 models, these evaluations split PV retrieval from structural understanding of hierarchical naming patterns, and offer strong dependency of end-to-end PV identification on the ALS control system's naming conventions.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

MOP6321_edited_version.pdf

16:00 Evaluation of error propagation in the first-order geodetic network of the FCC tunnel using topographical techniques

The Future Circular Collider (FCC-ee) is a next-generation electron-positron collider under design at CERN to advance particle physics beyond the Large Hadron Collider (LHC) era. This 91 km circumference accelerator, located at a depth of about 200 m underground, raises significant challenges for the alignment of its components. Thousands of elements must be positioned within a few tens of micrometers relative to each other to ensure optimal machine performance. To achieve this, a first-order alignment network, transferred from surface references, must be established along the entire length of the tunnel. This network will provide the basis for tracing, installation and absolute alignment of components prior to the relative alignment phase.

A dedicated simulation tool has been developed to model the FCC-ee tunnel, including shafts and bypasses. Different network configurations can be generated to simulate polar, gyroscopic, and levelling measurements. This paper presents the methodology used to build these simulations and studies the resulting error propagation and expected precision for each measurement configuration.

Speaker: Roberto Fernandez Bautista (European Organization for Nuclear Research)

16:00 Evaluation of low-cost, multimodal-sensor, data acquisition systems for ad-hoc applications in particle accelerators

With more than 30km of beam lines and over 10,000 devices, CERN's particle accelerators are rich sources of data, providing real opportunities for developing new equipment monitoring and automation tools using data analysis and machine learning.

The ready availability of low-cost computers and microcontrollers, such as Raspberry Pi and ESP32 devices, could enable a flexible data acquisition system for short-term applications that do not require, or cannot justify, the development and installation of permanent acquisition infrastructure.

This paper presents the initial work from a pilot project to develop such a system, and assesses its use for several applications, including speculative investigations of environmental conditions, such as temperature and high-energy hadron flux, as well as assessing the feasibility of detecting arc faults in power converters, and gathering datasets for training machine learning models.

Key considerations for the implementation of this system are also discussed, including concerns around network security, data quality, data availability, hardware configurations, deployment conditions, and avoiding control system dependency, with initial recommendations given for each.

Speaker: Patrick Ellison (European Organization for Nuclear Research)

16:00 Experiment Design for Beam-based Characterization of a sub-THz Double Bend Mode Converter

Laser-based high power THz generation advances rapidly, enabling THz-driven electron acceleration beyond the breakdown limits of conventional RF-driven structures. For this purpose the polarization of the externally coupled THz pulse has to match the required TM₀₁ mode. Vice versa, beam-driven high power THz generation also relies on the TM₀₁ mode and requires efficient out-coupling and transport. A crucial step in both applications is the conversion between the fundamental mode and the TMTM₀₁ in a compact manner, which can be achieved efficiently in a double bend geometry¹.

However, the double bend mode converter is fully integrated with the chained neighbouring devices. The embedding imposes challenges on the independent characterization of the converter, especially due to the strict tolerances. Utilising the wake field excited by an externally injected electron beam reduces the de-embedding complexity due to the requirements for THz in-coupling.
Following tolerance studies, a beam-based experiment at ARES at DESY is proposed to study the conversion quality of the mode converter at 165 GHz, the design frequency envisioned for the TWAC project². The wake-driven excitation enables a wideband characterization around the design frequency.

A gently compressed (≈1 ps rms) high charge (≈50 pC) electron bunch is passed through a dielectric loaded waveguide, thereby exciting the TM01 mode. The out-coupled, sub-µJ THz pulse will be polarization filtered to determine the relative mode content between the residual unconverted TM₀₁ and the expected TE₁₁.

Speaker: Max Joseph Kellermeier (Deutsches Elektronen-Synchrotron DESY)

MOP7002_edited_version.pdf

16:00 Experimental and First-Principles GGA-PBE Insights into SHI-Induced Defects and Local Bonding Among Different Grain Sizes in Ce₀.₇₅Gd₀.₂₅O₂

To evaluate radiation tolerance, 25 mol% Gd₂O₃-doped CeO₂ nano powders were synthesized by a sol-gel combustion route and sintered at 800°C, 1000°C, and 1300°C to obtain different grain sizes. The pellets were irradiated with 100 MeV iodine ions to simulate fission-fragment damage, and structural and electronic changes were examined using synchrotron GIXRD, Raman spectroscopy, EXAFS, XPS, and electron microscopy. Smaller grain-sized samples (800°C) exhibited more significant irradiation-induced degradation compared to larger grain-sized samples (1300°C), although both maintained their fluorite cubic structure at the highest ion fluence (1×10¹⁴ ions/cm²). EXAFS indicated Ce–O bond relaxation, Gd-coordination changes, and redistribution of oxygen vacancies. Raman peak broadening suggested vacancy-related defect complexes, and XPS revealed shifts in Ce³⁺/Ce⁴⁺ ratios and charge redistribution. First-principles GGA-PBE calculations support vacancy stabilization and local bonding rearrangement. The results highlight clear grain-size-dependent radiation response in Gd-doped CeO₂ and its relevance for nuclear and space applications.

Speaker: VIVEK KUMAR (Jawaharlal Nehru University)

16:00 Experimental study of beam-induced damage in Nb₃Sn sample coils pre-irradiated up to 30 MGy

Superconducting magnets of high-energy accelerators are vulnerable to beam-induced damage and previous experiments have characterized the damage limits of Nb$_3$Sn sample coils under proton-beam impact. This paper presents a follow-up experiment at CERN's HiRadMat facility investigating the combined effect of radiation ageing and beam impact on superconducting sample coils. The coils were pre-irradiated to simulate the integral dose anticipated for the final-focusing triplet quadrupole magnets of the High Luminosity LHC (HL-LHC) at the end of their lifetime. Following a review of the experimental motivation and preparation of the samples, the final experimental setup is described, including sample positioning and expected temperature profiles under beam impact. Metrology measurements, survey operations, and beam-based alignment, used to ensure adequate beam impact parameters, are detailed together with the proton beam parameters used to irradiate the samples. FLUKA simulations constrained by measured beam size, intensity, and position provide estimates for the local temperature rises and gradients. The timeline of the successfully completed experiment is reviewed. The ongoing post-irradiation analysis, including the assessment of beam-spot characteristics using radiation-sensitive film and the critical-current measurement campaign, is discussed in detail.

Speaker: Delphine Domange (European Organization for Nuclear Research)

MOV7005_edited_version.pdf

16:00 Experimental Study of Charging and Mobilisation of Dust Grains on Beam Screen Surfaces

Beam losses caused by interactions between the circulating beam and dust grains have been observed at many particle accelerators, leading to premature beam dumps, quenches of superconducting magnets, and vacuum pressure bursts. At some facilities, these events have a significant impact on the overall accelerator performance.
The mechanisms by which dust grains detach from vacuum-chamber surfaces and enter the beam are not yet fully understood; one possible process is charge build-up on the grain followed by lofting due to the beam potential.
We present an experimental study of the charging and mobilisation of silica dust on accelerator-relevant surfaces: Cu, co-laminated Cu, laser-treated Cu, NEG-coated substrates and samples treated with VacSeal, a silicone-based resin widely used to seal vacuum leaks.
The observations provide input for dust-dynamics simulations and studies of beam losses.

Speaker: Philipp Ziegler (Goethe University Frankfurt, European Organization for Nuclear Research)

MOP1075_edited_version.pdf

16:00 Experimental study of luminosity calibration corrections using tune scaling to mimic multi-collision configurations

Accurate luminosity calibration is essential for precise cross-section measurements and reliable machine performance optimization. In colliders with several interaction points, the cumulative beam–beam effects depend on the number of collision partners of individual bunches, which can bias luminosity calibration if not properly accounted for. To investigate this experimentally, a dedicated beam–beam experiment was performed at the LHC using tune scaling to mimic configurations with multiple collision partners within a single interaction region. By adjusting the fractional tunes, while preserving comparable beam–beam parameters, the dependence of luminosity calibration corrections on the effective number of collisions was systematically studied. The results are compared with expectations from numerical simulations, supporting the use of tune scaling as a valid strategy to reproduce multi-collision conditions for luminosity calibration corrections.

Speaker: Tatiana Pieloni (École Polytechnique Fédérale de Lausanne)

MOP1017_edited_version.pdf

16:00 Experimental validation of an additively manufactured 1.3 GHz radio frequency cavity

A compact continuous-wave (CW) 1.3GHz linear par
ticle accelerator (linac) is currently under development as
the core component of a high energy positron annihilation
lifetime spectroscopy setup. The associated thermal load
imposes stringent requirements on the design and manu
facturing of the underlying multi-cell radio-frequency (RF)
cavity. Metal-based laser powder bed fusion (PBF-LB/M)
has recently demonstrated the capability to fabricate pure
copperRFcavitiesasmonolithiccomponentswithintegrated
complex geometries, such as cooling channels. In this work,
we present and evaluate a first 1.3GHz single-cell RF cavity
as a prototype for the intended multi-cell structure, manufac
tured from pure copper using PBF-LB/M. Helium leak rate
and low-level RF measurements meet the linac expectations.
While the dimensional accuracy is reduced compared to con
ventional manufacturing approaches, it can be compensated
by an iterative design approach. These results demonstrate,
for the first time, the feasibility of PBF-LB/M as a manufac
turing route for monolithic 1.3GHz RF cavities.

Speaker: Mr Hermann Winter (Universität der Bundeswehr München)

MOP7171_edited_version.pdf

16:00 Experimental verification of energy dependence in a CNT wire monitor for beam profile measurements in the J-PARC Linac

The J-PARC linac accelerates a 50 mA H⁻ beam up to 400 MeV for user
operation. To mitigate emittance growth caused by space-charge effects,
transverse beam profiles are measured using wire scanner monitors (WSMs)
for routine beam tuning. Tungsten is generally used as the wire
material. However, the WSMs employ carbon nanotube (CNT) wires in the low-energy region between the RFQ and DTL, because the beam energy is low as 3 MeV and the thermal load is substantial. CNT wires were introduced in 2017 as a more heat-resistant alternative, and since then they have
operated without replacement due to beam-induced damage, demonstrating
excellent durability. In this study, we report beam profile measurements
obtained with the CNT WSM at various beam energies.

Speaker: Yong Liu (High Energy Accelerator Research Organization)

MOP6650_edited_version.pdf

16:00 Exploring causes of Beam Loss at CEBAF

At Jefferson Lab, the Continuous Electron Beam Accelerator (CEBAF) features a unique design with two linear accelerators and two arc sections allowing for multiple turns of the electron beam, as well as four experimental end stations. This topology leads to increased beam losses, especially in the spreader and recombiner regions connecting the arcs to the LINACs and in the extraction regions connecting the experimental end stations to the accelerator. These losses result in equipment activation and operational interruptions. Recent upgrades to the facility’s diagnostic systems, including the addition of xenon ion chambers, have provided higher-resolution data regarding these loss events. Building on this improved observational capability, we are developing a simulation framework using optics codes and the Geant4-based BDSIM to model beam extinction and halo formation in these regions. This work aims to correlate simulation results with experimental data to isolate the causes of beam loss and inform future machine tuning strategies. We present a summary of conclusions drawn from recent operational studies and outline a plan to model the beam loss and validate the simulations.

Speaker: Balsa Terzic (Old Dominion University)

MOP6381_edited_version.pdf

16:00 Facility-wide monitoring and early detection of failures at LANSCE

Accelerator complexes contain tens of thousands of interdependent components, and aging infrastructure amplifies the risk of equipment faults and costly, unscheduled shutdowns. At the Los Alamos Neutron Science Center (LANSCE), we are developing a data-driven framework that flags developing problems early enough to address them during scheduled maintenance, thereby improving reliability and increasing beam availability for users. Our approach analyzes all available signals within a subsystem to learn the facility’s “normal” operating envelope and to detect subtle deviations that precede failures. Unlike the current warning scheme, it captures hidden correlations among parameters and generates interpretable indicators of abnormal behavior. Predictions are validated against historical control-room log records. We report progress on three fronts: (i) extending anomaly prediction from a single beamline to all major LANSCE subsystems; (ii) expanding data archiving capacity by an order of magnitude to support broader coverage and longer look-back windows; and (iii) developing operator-facing algorithms that both warn of emerging anomalies and localize likely problem elements along the beamline. Together, these advances are designed to shift maintenance from emergency response to planned intervention, reducing downtime and enhancing overall facility performance.

Speaker: Nikolai Yampolsky (Los Alamos National Laboratory)

MOP6380_edited_version.pdf

16:00 FCC-ee energy calibration and polarization – towards the reference design

The FCC-ee aims at delivering high-precision particle-physics measurements over a wide beam-energy range, from the Z pole at 45.6 GeV up to 182.5 GeV, above the top-pair production threshold. Achieving the target physics precision requires an exceptionally accurate determination of the centre-of-mass energy and, consequently, of the beam energies. The baseline approach relies on resonant depolarization scan of dedicated, transversely polarized pilot bunches up to 80 GeV. By analysing the depolarization signatures with a 3D polarimeter, the spin tune can be extracted with a goal of reaching systematic uncertainties on the beam energy at the level of up to a few 10 keV.
This contribution presents the latest progress of the FCC-ee Energy Calibration and Polarization Working Group, covering recent developments in polarization build-up studies, resonant-depolarization techniques, machine-optics optimization, and polarimetry concepts. The current status is summarized, and the roadmap of technical and conceptual milestones required for the reference design is outlined.

Speaker: Jacqueline Keintzel (European Organization for Nuclear Research)

MOP1037_edited_version.pdf

16:00 FCC-ee injector complex: status, highlights and outlook

The FCC-ee demands an injector complex capable of delivering high-current, high-brightness electron and positron beams with exceptional efficiency. Within the CHART/FCC-ee Injector Study collaboration, a revised injector layout has been developed to optimize performance, cost, and power consumption. A central pillar of this effort is the tuning-free, high-gradient normal-conducting RF structure technology pioneered at PSI for SwissFEL and since extended across S-, C-, and X-band systems. This scalable approach underpins future developments in the FCC-ee linacs, enabling reliable acceleration. In parallel, the P³ program at PSI is advancing the positron source, with commissioning foreseen in 2026, while upcoming work will enhance the electron source and refine RF requirements for the positron linac. This contribution presents the current injector complex status, key design highlights, and the outlook toward the FCC-ee injector technical design report.

Speaker: Paolo Craievich (Paul Scherrer Institute)

MOV1003_edited_version.pdf

16:00 FCC-ee Optics Tuning – Towards the reference design

The Future electron positron Circular Collider, FCC-ee, is a proposed next-generation facility designed to deliver very high luminosities across a broad beam-energy range, from the Z pole at 45.6 GeV up to 182.5 GeV. Achieving the target performance in the presence of realistic lattice imperfections represents a significant challenge. To address this, a comprehensive commissioning strategy is being developed, featuring dedicated optics configurations, robust beam-based alignment procedures, and advanced optics-correction techniques supported by refined beam-based measurements.
In parallel, specifications for the main magnet families, corrector circuits, and required instrumentation are being explored to ensure compatibility with the expected tuning procedures. This contribution summarizes the current status of these developments and outlines the key steps and milestones envisioned on the path toward the reference design.

Speaker: Jacqueline Keintzel (European Organization for Nuclear Research)

MOP1039_edited_version.pdf

16:00 FEA–CFD numerical approaches in the design of the Fast Periodic Shutter for FAXTOR-BL31 at ALBA

In the context of the experiments to be carried out at the fast X-ray tomography and radioscopy beamline (FAXTOR-BL31) of the ALBA synchrotron, a Fast Periodic Shutter (FPS) is being designed. Its purpose is to prevent a high dose rate on the sample and to provide synchronization with the acquisition protocol. This FPS is based on the combination of tungsten blades driven by a servomotor.
This work details the FEA-CFD numerical simulations (ANSYS) developed for the FPS's thermo-mechanical design. Models considered steady-state and transient (periodic) conditions. Initial steady-state analysis (under vacuum) quantified baseline mechanical stress. Subsequently, a coupled CFD approach modeled the cooling gas and forced convection effects. The thermal modeling incorporated combined synchrotron radiation and Stefan-Boltzmann radiation modeling.
The main objective of these simulations is to quantify the resulting thermo-mechanical stress and temperature distribution to ensure the structural integrity of the blades. Complementarily, the influence of air resistivity on rotor performance and the temperature dynamic considering air cooling and periodic radiation were examined.

Speaker: Dr Marcos Quispe (ALBA Synchrotron (Spain))

MOP7156_edited_version.pdf

16:00 Femtosecond-Micron Resolution Electron Bunch Diagnostics via Laser-Drilled Diamond X-ray Optics

We report a technique for fabricating optically transparent x-ray optics by laser drilling precision pinholes in diamond membranes. This work supports a novel diagnostic under development at SLAC which will profile the Coulomb field of relativistic electron bunches with femtosecond-um spatio-temportal resolution.

Diamond is chosen for its specific transmission window extending from RF through UV (relevant for preserving the space charge field of the electron bunch). It is also very robust, however, thin free-standing diamond is challenging to process. In this proceedings, we describe a laser drilling setup with integrated laser-profiling measurements capable of generating <30um holes in 2um thick, 2mm diameter diamond membranes. A Ti:Sapphire laser was focused on the membrane, mounted on a three-axis positioning system. A python code automatically performs knife edge scans of the gaussian intensity profile to plot the waist at multiple z positions, mapping the complete waist profile versus propagation distance. The membrane is then positioned at the z location of the desired hole diameter, and the laser power is increased past the ablation limit to create a precisely sized pinhole at the target location.

This technique enables cnc fabrication with micron accuracy without requiring complex lithography or mechanical drilling, and is broadly applicable to precision micro-machining of thin, brittle substrates.

Speaker: Sean OTool (Stanford University)

16:00 FERMI Linac upgrade: commissioning experience of the first S-band High-Gradient Module

The FERMI seeded free-electron laser (FEL), located at the Elettra laboratory in Trieste, is a 4th-generation light source operating in the vacuum ultraviolet to soft X-rays range. In order to extend the FEL spectral range to shorter wavelengths, an increase in the linear accelerator (linac) energy from 1.5 to 2.0 GeV is required. S-band HG module is designed to fulfil the upgrade requirement of 30 MV/m accelerating gradient with the breakdown rate (BDR) in the range of low 10-8 bpp/m. One HG module consists of two HG structures, 3.0 m in length, and one Spherical Pulse Compressor (SPC). The 1st HG module is successfully commissioned at the FERMI linac up to an accelerating gradient of 27 MV/m with the BDR of around 5 x 10-8 bpp/m. In this paper, we share the commissiong experience of the HG module from installation, conditioning, high power operation, and commissioning with the beam.

Speaker: Nuaman Shafqat (Elettra-Sincrotrone Trieste S.C.p.A.)

MOP1092_edited_version.pdf

16:00 FGC Private Network: low-latency communication standard for the future controls of power converters at CERN

The CERN Electrical Power Converters (EPC) group operates thousands of converters, most via the Function Generator/Controller (FGC) device family. Its new generation, FGC4, built on an AMD Zynq UltraScale+ MPSoC, will support future EPC applications. Some, like POPS+, require low‑latency inter‑FGC communication. We present the FGC Private Network (FPN) protocol stack and library enabling this private, real‑time network.

FGC4 software runs on four Cortex-A53 cores: two of which are dedicated to real-time regulation on bare‑metal, and the other two run background and frontend services under Linux. The Programmable Logic (PL) hosts two GbE endpoints able to fetch application data via cache‑coherent DMA and transmit them over a switched Ethernet network, meeting a tight 10 µs control budget.

The FPN implementation is split between software and gateware. To ensure consistency, protocol-related definitions in C++, VHDL, as well as debugging utilities, are all generated from YAML definitions acting as the single source of truth.

The C++ library minimizes CPU usage without compromising on clarity, and supports interchangeable transport layers (PL GbE, generic Ethernet, UDP, file replay...) for desktop development, regression testing, and Hardware-in-the-Loop validation.
This model‑driven, flexible and testable approach paves the way for POPS+ deployment on FGC4 and enables future EPC systems.

Speaker: Clément Zrounba (European Organization for Nuclear Research)

16:00 Field Quality of MQXFB Quadrupoles for HL-LHC

This paper presents the main results of the magnetic measurements performed on the available MQXFB quadrupoles at room and cryogenic temperature. The measurement program, carried out during the different stages of the magnet assembly and by using different instruments such as the rotating-coil and stretched-wire systems, allows an early identification of the field errors and a comprehensive characterization of the field quality. A fine tuning of the low-order multipoles is achieved by magnetic shims using iron inserts, which provides a means for improving the field quality of some magnets. The transfer function, the field harmonics, and the effects of superconductor magnetization and iron saturation are reported. In addition, a warm-to-cold extrapolation method is developed for the prediction of the integrated gradient at 1.9 K and nominal current, with an accuracy within 5·10-4, allowing a proper sorting of the magnets at an early stage and before the final cold test. In conclusion, all the MQXFB magnets tested so far meet the field-quality requirements for the HL-LHC, and the adopted measurement and correction strategy has proven to be effective for the series production.

Speaker: Matthias Bonora-Tam (European Organization for Nuclear Research)

MOP7083_edited_version.pdf

16:00 Field-Quality Characterization of a Tunable Permanent-Magnet Quadrupole Using Rotating-Coil Measurements

A tunable permanent-magnet quadrupole based on two independently rotatable Halbach rings has been developed for compact, low-energy beam transport systems. Previously characterized with Hall-probe measurements, the same prototype is here studied using a high-precision rotating-coil bench at CERN, in the frame of a long-standing collaboration with the Wigner Institute. The integrated gradient, field orientation, and higher-order multipole components were measured over the full tuning range by scanning the relative rotation angle of the two rings. The quadrupole field is well described by a simple two-parameter model, allowing extraction of the individual ring strengths and azimuthal offsets. After correction for global alignment errors, residual multipole components remain within ±40 units over the operating range. Measurements under synchronous ring rotation show that higher-order multipoles rigidly follow the quadrupole field, indicating negligible hysteresis and minor mechanical coupling effects. These results confirm the excellent field quality and robustness of the concept and provide quantitative input for optimization and use in ion-source front-end beamlines.

Speaker: Gábor Anda (HUN-REN Centre for Energy Research)

16:00 First Beam Demonstration in Hand-Portable Battery-Operated 2 MeV Ku-band Split Linac

This talk reports on the design, fabrication, and beam testing of a novel 2 MeV Ku-band (15.14 GHz) traveling wave electron linear accelerator developed by RadiaBeam Technologies for a battery-powered, hand-portable X-ray generator intended for field radiography and non-destructive testing (NDT). The goal is to replace hazardous isotopes, such as Ir-192, Cs-137, and bulky betatrons with a compact, adjustable, and safer radiation source.
The system achieves dramatic miniaturization by combining several innovations: use of a 250 kW peak power air-cooled magnetron for reduced accelerator size while maintaining sufficient beam energy; a split accelerating structure fabrication method, machining both halves of the structure in one piece to eliminate the need for post-brazing tuning, reduce manufacturing errors, and improve vacuum conductance; and an ultra-compact solid-state Marx modulator, weighing ~1.2 kg, operable from two Li-Ion batteries.

Speaker: Sergey Kutsaev (RadiaBeam Technologies (United States))

16:00 First Demonstration of High-Charge Relativistic Positron Beam Phase-Space Evolution Measurement via Complex Computed Tomography at SuperKEKB

The SuperKEKB collider aims to surpass the previous luminosity record of its predecessor by 40 times. The understanding of the electron and positron beam phase-space (P-S) is of upmost importance to understand the efficiency of the machine and also to be able to plan possible improvements and anticipate the machine limits. Multiple diagnostics are capable of giving global information about the beam. However, an accurate real beam P-S distribution is of great relevance not only experimentally but also for simulations. By knowing how the beam P-S looks and evolves, one can make sure that the simulations are accurate, predict ring injection, and can be used as input for simulations among other things. The measurement of a full 2D P-S is not easy task, and it is usually prepared from the beamline design stages. One such technique is the computed tomography, first applied to beams in 1995*, and based on the beam P-S reconstruction via the analysis of 1D projections at different phase-space rotation angles. In this work we present the use of this technique at SuperKEKB to obtain both transverse 2D beam P-S and the evolution of the phase-space along 10 m of the beamline. The main novelties of this work are the use of a normal non prepared beamline (as no changes were possible) with a complex setup (1 OTR screen and different groups of >3 quadrupoles along ~45m) and its use to see the evolution at different points of the beamline. Comparisons with simulations are also presented.

Speaker: Dr Driss Oumbarek Espinos (High Energy Accelerator Research Organization)

16:00 First look at the impact of beam-beam effects on the luminosity scan observables

During the operation of the Large Hadron Collider (LHC), regular beam separation (luminosity) scans are essential for accurately determining beam emittance and give valuable observables for monitoring the stability of luminometers. These scans provide a critical insight into beam quality and detector performance. In this study, we investigate how beam-beam interactions influence luminosity scan observables by combining numerical simulations and experimental data, and discuss the resulting implications for measurement accuracy.

Speakers: Jorg Wenninger (European Organization for Nuclear Research), Tatiana Pieloni (École Polytechnique Fédérale de Lausanne)

MOP1063_edited_version.pdf

16:00 First observation of controlled beam-halo population and cleaning at the LHC by an AC dipole

Experimental observations indicate that a significant fraction of the stored beam energy in the CERN Large Hadron Collider (LHC) is contained in the transverse beam halo. Combined with the anticipated increase in beam brightness in the High-Luminosity LHC (HL-LHC) and new expected fast failure scenarios resulting in a loss of large-amplitude particles, an overpopulated beam halo poses risk to the safe operation of the machine. Following removal from the HL-LHC baseline of the Hollow Electron Lens, which was studied as the preferred method for active halo control, alternative halo-cleaning methods need to be investigated. A novel method being explored is the use of an AC multipole operated in resonance with the betatron tune to create a stable island in phase space in which halo particles are adiabatically trapped and transported to the collimators in a controlled manner. This paper presents the results of the first successful proof-of-principle measurement of both controlled beam-halo population and cleaning using an AC dipole at the LHC.

Speaker: Massimo Giovannozzi (European Organization for Nuclear Research)

MOP1109_edited_version.pdf

16:00 First results from the SUNDAE1 test stand at European XFEL

European XFEL is planning the installation of superconducting undulators as afterburners downstream with respect to SASE2, one of the hard X-ray undulator lines, to provide even harder X-ray photon energies and a larger tuning range. The Superconducting undulator PRE-SerieS mOdule (S-PRESSO) consisting of two pair of coils, a phase shifter, and correction coils is in production by Bilfinger Nuclear & Energy Transition GmbH.

In order to perform quality assurance of the superconducting coils a vertical test stand SUNDAE 1 (Superconducting UNDulAtor Experiment) has been developed. SUNDAE1 allows to train the superconducting coils, as well as to measure the magnetic peak field profile by means of Hall probes. We report here on first results.

Speaker: Dr Ahmed Elghandour (European X-Ray Free-Electron Laser)

MOP7125_edited_version.pdf

16:00 First results on fast Ion instability in the FCC-ee injector complex damping ring

The FCC-ee injector complex includes a dedicated damping ring planned to operate at 2.86 GeV energy to reduce the emittance of the incoming electron and positron beams prior to their injection into the high-energy linac, where they will be accelerated up to 20 GeV for the main booster ring. Ionization of the residual gas caused by interacting with the circulating bunches may occur, and these ions can be trapped and accumulated by the fields of the electron beam. This process may lead to fast beam–ion instabilities, potentially affecting beam quality in the damping ring.
This study investigates the mechanisms of ion creation, accumulation and trapping across the considered FCC-ee damping-ring lattice options. A range of vacuum conditions, gas compositions and bunch parameters are explored to identify the operational regimes in which fast ion instabilities may become significant.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

MOP1108_edited_version.pdf

16:00 From concept to feasibility: optimised design studies of the Alice fixed-target configuration for lead ions at the HL-LHC

The ALICE fixed-target (ALICE-FT) programme uses crystal-assisted halo splitting to send a controlled flux of beam-halo particles onto an internal target upstream of the ALICE interaction point, enabling a rich fixed-target physics programme in parallel to collider running. We present the final feasibility assessment for operation with HL-LHC Pb beams.

Using SixTrack–FLUKA tracking with particle–matter interactions, we scan optics, crystal parameters and target/absorber geometry. The phase advance between the IR7 collimation system and the ALICE-FT crystal, as well as the crystal bending angle and alignment, are optimised to maximise halo interception and channeling to the target while preserving the collimation hierarchy. The optimised layout increases the fraction of halo particles on target, delivers fixed-target luminosities compatible with the projected ALICE heavy-ion programme and keeps additional losses within machine-protection limits. We conclude with an operational scenario and prospects for an experimental demonstration of the concept.

Speaker: Marcin Patecki (Warsaw University of Technology)

MOP1027_edited_version.pdf

16:00 From lattice to engineering design: a rapid, reliable development cycle

The future PETRA IV synchrotron radiation facility at DESY, Hamburg will be a 4th generation light source in the 2.3km long PETRA tunnel, with first light in 2032. It comprises 8 straight sections and 8 arcs with 288 girders and space for 72 insertions.

The hybrid 6 bend achromat accelerator lattice aims for as much periodicity as possible to maximise symmetry, which is beneficial for beam dynamics, and minimise cell design variants. However, straight sections each fulfilling differing functions such as injection, rf acceleration or photon generation, more than a dozen variants of insertion devices, and differing tunnel cross sections introduce substantial variability of girders, cells, and arcs, increasing the engineering effort.

We have set up an engineering process, supported by a set of automated tools, that establishes a rapid, reliable translation of the lattice to the positions of all components that act on the beam. More than 6000 individual beamline elements are positioned in this way.As part of the process, we analyse girder variants to minimise the number of different mechanical designs for magnets, vacuum, and other systems, and to facilitate logistics processes.A managed change process ensures that lattice updates are systematically propagated to the engineering design.

Speaker: Benno List (Deutsches Elektronen-Synchrotron DESY)

16:00 Functionalised a-C coatings to reduce SEY and control surface resistance for the HL-LHC injection kicker beam-pipe ceramic supports

Functionalized amorphous carbon (a-C) coatings are being developed to reduce the secondary electron emission yield (SEY) and to control the surface resistance of ceramic supports for the new generation of HL-LHC injection kicker magnets. Pressure spikes observed during high-voltage pulsing of the new injection kicker magnets are attributed to flashovers caused by high electron emission and insufficient draining of surface charge on the alumina supports of the beam-pipe. To address this issue, the alumina supports for the next generation of injection kicker magnets are coated with an a-C film, providing suitable surface resistivity to prevent charge accumulation whilst preserving the insulating function of the supports, together with a low SEY.
This contribution reports on the R&D programme aimed at tuning the resistivity of the a-C films through hydrogen doping while maintaining acceptable SEY performance. Results from the production of a series of 25 coated supports are presented, along with comple-mentary studies carried out to optimise the coating pro-cess for future large-scale production. The potential of these resistive a-C films as alternatives to Ti and TiN coatings for insulating components is also discussed.

Speaker: Dr Marcel Himmerlich (European Organization for Nuclear Research)

MOP7102_edited_version.pdf

16:00 Genetic optimizations of RF cell profile using Superfish

Important RF cell parameters such as the shunt impedance 𝑅𝑠, the quality factor 𝑄, and the ratio of accelerating to peak field, depend on the cell geometry. Thus, it is desirable to optimize the cell profile to optimize the performance of the cell. The use of B-splines to optimize cell profiles with a genetic algorithm has been demonstrated. The RF field solver Superfish, however, does not support defining cell geometries using B-splines. Here we discuss a similar approach using only linear and elliptical segments supported by Superfish to define the cell geometry, making it possible to carry out genetic optimizations with Superfish.

Speaker: Michael Kaemingk (Los Alamos National Laboratory)

MOP6395_edited_version.pdf

16:00 Hardware Aware Artificial Intelligence (HAAI): progress on realtime beam tomography reconstruction for the Fermilab Recycler using machine learning and edge processing

The resistive wall current monitor (RWCM) data from the Fermilab Recycler Ring (RR) is used to reconstruct the longitudinal profile of proton beams circulating in the machine. This procedure, commonly referred to as tomography, has proved to be invaluable in tuning the machine. In 2013 Recycler was re-purposed as a proton stacker and charged with implementing slip-stacking to double the intensity for the Main Injector (MI). With two slipping beams, the RWCM data from Recycler is difficult to differentiate and the tomography procedure is slow to compute using traditional means. Building upon past efforts, the Hardware Aware Artificial Intelligence (HAAI) project aims to develop a ML model to reconstruct the Recycler beam tomography in real-time and deploy this model on edge hardware. Once developed, this new streaming virtual diagnostic would be used to better track the beam parameters over larger time spans, attribute settings to beam effects, tune the machine, and provide an input into other future automatons of the machines.

Speaker: Kyle Hazelwood (Fermi National Accelerator Laboratory)

MOP6316_edited_version.pdf

16:00 High-intensity LHC tests in 2025 for transverse beam dynamics studies

During dedicated machine development periods in 2025, the LHC operated with High-Luminosity LHC (HL-LHC) beam parameters to study transverse beam dynamics in a high-intensity and high pile-up regime. For the first time, collisions with trains of $2.3\times10^{11}$~ppb were achieved, reaching a pile-up of 150 and reproducing operational conditions close to those foreseen for the HL-LHC. These experimental tests allowed for detailed measurements of emittance growth and proton losses. In particular, a fill with bunches having different transverse distributions was performed to assess the impact of non-Gaussian tails on beam lifetime and losses beyond the burn-off limit when the two beams are brought into collisions.
Furthermore, the evolution of the beam quality throughout the cycle was studied for different HL-LHC beam types. These results represent a key milestone towards the demonstration of the HL-LHC operational conditions.

Speaker: Guido Sterbini (European Organization for Nuclear Research)

MOV1001_edited_version.pdf

16:00 High-power test and system integration of direct RF sampling based LLRF control and monitoring system for S-band accelerating structures

High precision Low-level RF (LLRF) control and monitoring systems for future particle accelerators will be a significant technical challenge as the requirements in performance, flexibility and affordability become increasingly stringent. We have developed an RF system-on-chip (RFSoC) based next generation LLRF (NG-LLRF) for S-band accelerating structures, which samples and synthesizes the RF pulses directly without the analog mixers used for traditional LLRF systems. The platform delivered considerably better performance than the requirements of the targeted applications, such as the upgrades for Next Linear Collider Test Accelerator (NLCTA) and test facilities at SLAC. As part of the upgrade program, we also developed a custom solid-state amplifier (SSA) to deliver RF pulses at desired power level of the klystron. The integration of the LLRF with SSA and the high-power test facility could be challenging. The power levels and RF pulse stability at each stage of the high-power RF drive system need to be optimized to deliver the desired RF performance. In this paper, the integration procedure and the test and characterization results at each stage of integration will be summarized, analyzed and discussed. This integration is an essential step for the full deployment of the NG-LLRF system to the test facilities and accelerators in different frequency bands.

Speaker: Wei Hou Tan (SLAC National Accelerator Laboratory)

MOP6389_edited_version.pdf

16:00 High-power test of a 40kW industrial electronic linear accelerator

Electron accelerators with high average power output are widely used in radiation processing fields such as material modification, food sterilization, and environmental pollutant treatment. This paper presents a comprehensive high-power test of a 40kW electron accelerator. Key parameters including electron beam energy, average beam current, output power, and pulse characteristics were measured. The results show that the accelerator’s electron beam energy, the average beam current, and the effective output power all meet the design specifications. The energy test was performed via the aluminum foil stacking method, ensuring high measurement accuracy. This study validates the reliability and stability of the accelerator, providing technical support for its industrial application.

Speaker: Yan Zhao (Tsinghua University)

MOP8621_edited_version.pdf

16:00 High-voltage coils optimization for the LHC beam dump dilutor kicker magnets

Two sets of 6 fast-pulsed vertical and two sets of 4 fast-pulsed horizontal dilutor kicker magnets form part of the so-called LHC beam dumping system, which removes the counter-rotating beams safely from the collider onto an absorber block. Each vertical and horizontal diluter magnet is powered by a pulse generator via a low-impedance transmission line resulting in maximum damped sinusoidal voltage of 16 kV and a maximum damped sinusoidal current pulse of 30 kA.

The fast-pulsed dilutor kickers magnets, MKBV and MKBH, consist of a steel yoke with excitation coils, which are immersed in the accelerator vacuum.

As part of a consolidation program, high-voltage insulated coil spares will be manufactured. The coils are composed of conductor bars of quasi-rectangular cross-section, junction pieces, and conductor contact pieces. The coils are completely insulated for the 16 kV and 10 kV peak voltages. The surface of the insulation is coated with a resistive layer and connected to earth. The connector contact terminals are molded sockets, surrounded by stress rings.

This paper describes the design of the MKBV and MKBH kicker magnets, focusing on the fabrication processes and validation tests for both types of coils.

Speaker: Vasco Gomes Namora (European Organization for Nuclear Research)

MOP7130_edited_version.pdf

16:00 Hight Voltage Electric dipole conditioning for the Super spectrometer separator at GANIL/SPIRAL2

The “Super Separator Spectrometer” project S3 is under technical commissioning at the GANIL facility (Caen-France). It is a new research installation designed for fundamental physics experiments with high intensity radioactive heavy ions beams produced by the SPIRAL2 linear accelerator. This spectrometer will open new horizons for nuclear physics.
The S3 spectrometer is made of 77 superconducting magnets, 12 room temperature magnets and one high-electric field dipole.
This electric dipole combined with a magnetic dipole will allows a very precise energy/mass selection of ions with extremely small effective sections.
This paper presents the electric dipole technology and its initial high voltage conditioning carried out on-site in 2025.

Speaker: Franck Esnault (Grand Accélérateur National d'Ions Lourds, Commissariat à l'Énergie Atomique et aux Énergies Alternatives)

MOP7168_edited_version.pdf

16:00 HiPIMS Nb Thin Films for SRF Cavities

Nb-coated Cu Superconducting Radio Frequency (SRF) cavities are a key technology for the Future Circular Collider (FCC), requiring performance beyond the current state of the art. Recent Nb/Cu coatings deposited by High Power Impulse Magnetron Sputtering (HiPIMS), together with advances in Cu cavity manufacturing and surface preparation, have already shown promising results*.

To further optimize film quality, we investigated the influence of ion-bombardment energy during HiPIMS on the superconducting and microstructural properties of Nb. Particular focus was placed on the critical current density, Jc, as an indicator of vortex pinning and flux trapping, which constitute key RF-limiting factors.

By tuning ion-energy distribution, Jc was reduced by up to an order of magnitude, with an optimal value around ~75 eV. A clear correlation between Jc and cavity performance demonstrates ion-energy control as an effective lever to improve Nb/Cu SRF technology for FCC-ee, and establishes Jc as a reliable predictor of RF behavior.

Speaker: Carlota Pereira Carlos (European Organization for Nuclear Research)

16:00 HL-LHC BGI mechanical design: integration, impedance and vacuum aspects.

A new Beam Gas Ionisation monitor is being designed for the HL-LHC era. The paper described the challenges for the mechanical design of the instrument taking into consideration the instrument functionality, impedance compatibility, vacuum acceptance and tunnel integration. The new design takes into consideration as well the lessons learnt from the operation of these monitors in the injectors chain (PS and SPS) throughout the past 10 years.
Four new instruments will be installed during the Long Shutdown 3, providing transverse beam profile measurements in the horizontal and vertical planes for both beam 1 and beam 2.

Speaker: Chiara Pasquino (European Organization for Nuclear Research)

MOP1118_edited_version.pdf

16:00 Hybrid online optimization for hands-off tuning of the ALS injector

Reliable hands-off injector operation calls for fast, sample-efficient tuning under drift and competing goals (e.g., capture efficiency, energy spread, transmitted charge). We present an autotuning framework for the ALS injector combining complementary online optimizers for robust performance under strict machine-protection/operability constraints. The controller alternates methods based on objective structure and information gain, fusing diagnostics across longitudinal and transverse systems. Building on prior Bayesian and multi-objective optimization, we add extensions for tracking a moving Pareto front during drifts, time-decayed learning for stability, and global-exploration bursts to escape trade-off plateaus. On the ALS linac, we target figures of merit tied to bottlenecks (e.g., controlling beam loading-driven energy spread challenging the booster acceptance) and enforce safety via bounded steps and surrogate constraints. Initial studies show shorter tuning time and improved repeatability vs. single-method baselines while preserving capture within the booster ring’s tight longitudinal window; we summarize architecture, decision logic, and portability.

Speaker: Gianluca Martino (Lawrence Berkeley National Laboratory)

MOP6330_edited_version.pdf

16:00 Impact of dipole field quality on the emittance tuning and the dynamic aperture of the High Energy Booster of the Future Circular Colliders

We present the impact of the main dipole field quality on the dynamic aperture (DA) and the emittance tuning of the High Energy Booster (HEB) of the leptonic version of the future circular colliders. Multipole field imperfections up to order six (normal: b2–b6; skew: a2–a6) are introduced into the main dipoles using measured values, interpolated at 8.8 mT (the HEB injection energy), and systematic errors of one unit.
The study evaluates the degradation of the total DA as a function of the energy offset, computed for several angles in the transverse plane (x–y).
The impact on the emittance achieved following optics correction and correctors strength is also evaluated.
Correction of linear chromaticity and Montague functions, together with second-order dispersion, are discussed.
Key results show that even small multipolar errors can significantly impact optics stability, and further iterations with magnet experts are required to define tolerances of field quality and correctors specifications.
The approach and scripts developed here (using the Xsuite modules) enable the rapid testing of various error configurations and can be adapted for future optimisation.

Speaker: Quentin Bruant (Commissariat à l'Énergie Atomique et aux Énergies Alternatives)

16:00 Impact of intrabeam scattering and space-charge in the first three cells of the Muon final Collider cooling channel

The cooling process is one of the most critical challenges for the future Muon Collider, as muons are initially produced with a very large emittance that must be significantly reduced before acceleration. This cooling must occur rapidly, well within the muon lifetime. At low energies, collective effects such as space charge and intrabeam scattering can strongly influence emittance growth and must therefore be considered in the lattice design, which is currently under development. This work presents studies of space charge and intrabeam scattering effects within the first three cells of the latest Muon Collider final cooling lattice design evaluating their impact on emittance growth using the tracking code RF-Track.

Speaker: Paula Desire Valdor (European Organization for Nuclear Research, University of Groningen)

MOP1100_edited_version.pdf

16:00 Impact of rapid acceleration on beam dynamics in the rapid-cycling synchrotrons of a muon collider

Circular muon colliders offer a promising route to multi-TeV center-of-mass energies with high luminosity. The baseline design for the high-energy complex includes a chain of pulsed synchrotrons covering energies from 63 GeV to 5 TeV. This chain combines normal and hybrid synchrotrons, using both fixed-field superconducting and pulsed normal-conducting magnets. The short muon lifetime (2.2 microseconds in the rest frame) constitutes a major challenge for the accelerator complex: attaining high luminosity requires a muon survival rate of up to 70 % throughout the acceleration chain, implying acceleration within a few milliseconds. Such rapid acceleration causes a mismatch between the beam energy in the arcs and the linearly ramped fields of the dipoles and quadrupoles. The corresponding field errors affect both the beam trajectory and optical functions. Preliminary tracking studies have been conducted to assess the emittance growth arising from these effects.

Speaker: Lisa Soubirou (Université Paris-Saclay)

MOP1094_edited_version.pdf

16:00 Implementation and design of a laser neutralizer in the LANSCE lebt

We present the detailed design and hardware implementation required to build a laser wire scanner for H- bunches at the Los Alamos Neutron Science Center (LANSCE) in the low energy beam transport (LEBT) section of the LANSCE beam line. The presented design is modular and supports a variety of input laser beam orientations, as well as differing laser beam diameters and powers. A custom-built laser interaction point, and drift chamber are added to the current beam line to photo-ionize the H- secondary electrons and collect the freed electrons in a custom-built, high-speed Faraday cup detector. Our chamber design is modular and constructed to minimally impact LANSCE production, while also allowing for in-run cycle reconfigurations. This setup will allow for the testing of a variety of laser system diagnostics configurations at the LANSCE facility. Future directions for direct separation and spatially resolved detection of the neutral hydrogen and charged anions will also be presented.

Speaker: Charles Rohde (Los Alamos National Laboratory)

MOP6379_edited_version.pdf

16:00 Implementation and performance evaluation of a high-resolution bunch-by-bunch phase detection system with geometric calibration

A high-resolution, real-time bunch-by-bunch phase detection system has been developed and deployed at the Taiwan Photon Source (TPS) to monitor and analyze synchronous phase behavior. The system is integrated with the control system to implement the remote phase adjustment function. The detector architecture utilizes an analog I/Q demodulation scheme operating at the 1.5 GHz third harmonic of the RF frequency to achieve precise phase extraction. Limited by hardware non-idealities, DC offsets and quadrature phase imbalances distort the I/Q signal trajectory into an elliptical profile, leading to periodic measurement errors. To address these issues, a digital calibration strategy based on ellipse-fitting is implemented to eliminate offsets and quadrature errors within the I/Q channels.
After calibration, the phase error of this system at 1.5 GHz is within 1.5°, therefore, when used to measure a 500 MHz signal, the corresponding phase error is within ±0.5°. The extracted phase data is integrated into the accelerator control system with a 3 Hz update rate, enabling real-time visualization of transient beam loading effects. Furthermore, the system’s capability to record 700 turns of bunch motion for phase variation analysis.

Speaker: Jui-Che Huang (National Synchrotron Radiation Research Center)

MOP6665_edited_version.pdf

16:00 Implementation of fast beam-based alignment at the Taiwan Photon Source

A fast beam-based alignment (BBA) method has been implemented at the Taiwan Photon Source to significantly enhance the efficiency of aligning beam position monitors with quadrupole magnet centers. By utilizing sinusoidal excitation of correctors and employing synchronous detection algorithms, alignment offsets are efficiently extracted across the entire storage ring. Experimental results demonstrate that the total measurement time is reduced from 8 hours to under 40 minutes, while maintaining precision comparable to conventional BBA methods. The primary sources of measurement uncertainty are attributed to betatron tune and orbit variations induced by magnetic hysteresis and ocean-induced ground motion. This approach provides a robust and time-efficient solution for routine orbit characterization in modern synchrotron light sources.

Speaker: Chunyi Wu (National Synchrotron Radiation Research Center)

16:00 Improving helium sustainability: current performance and upgrade of the ALBA helium liquefaction facility

Efficient use of gaseous and liquid helium, a non-renewable resource essential for accelerator-based experiments, is a key priority at ALBA Synchrotron Light Source. This work presents the operational status of ALBA’s helium liquefaction plant and the liquid-helium production achieved in recent years, based on recovery from its use in the BOREAS, LOREA, CLAESS and MSPD beamlines. The helium liquefaction plant’s operating mode is discussed, with emphasis on its main limitation: the system can only process recovered gas with an average helium purity of 99.5%. To overcome this constraint, the plant was upgraded during 2025–2026 with the installation of a gas purifier capable of treating gas helium with purities as low as 90%. The first operational results and performance of the helium liquefaction plant with the integrated purifier are presented.

Speaker: Dr Marcos Quispe (ALBA Synchrotron (Spain))

MOP7086_edited_version.pdf

16:00 In-air optical techniques for temporal diagnostics at picosecond resolution

Radiative temporal diagnostics like Cherenkov diffraction radiation easily offer ps-resolution but require in-vacuum operation. For detectors in air, prompt Cherenkov radiation (ChR) provides ps-resolution while greatly reducing deployment complexity. We investigate such in-air ChR diagnostics to resolve sub-ns bunch structure at the Australian Synchrotron's injector linac. Existing monitors can resolve \qty{2}{ns} bunch spacing but cannot detect possible \qty{330}{ps} satellite bunches induced by \qty{3}{GHz} travelling-wave structures. A mirrored silica crystal is considered for generating and guiding ChR towards a photodetector. Impacts of path-length dispersion in the crystal are assessed, alongside optimisation of photodetector placement relative to the crystal. Ability of existing diagnostics (such as a Fast Current Transformer) to resolve sub-ns bunch structure is assessed. Existing diagnostics serve to benchmark the performance of novel monitors exploiting the mirrored crystal. These techniques support improved longitudinal phase-space measurement, thus increasing injection efficiency, improving bunch purity, and optimising RF-phasing in a dual-RF system.

Speaker: Joel Valerian (The University of Melbourne)

16:00 In-situ XPS study of Nb surface during mid-T bake with plasma treatment for SRF cavities

Specific heat treatments applied to superconducting radio-frequency (SRF) cavities, such as nitrogen infusion or Mid-T baking, aim to improve the quality factor (Qo) at medium accelerating fields (˜10–20 MV/m). These treatments reduce the BCS surface resistance by tuning the mean free path of niobium over a few hundred nanometers, either by diffusing oxygen from the native oxide layer or by diffusing nitrogen after the dissolution of the oxide layer. However, these treatments preclude the usual chemical polishing, as it would reverse the beneficial effects of the heat treatments, making the cavities highly sensitive to surface contamination. In particular, the formation of niobium carbides, which can mask the expected benefits, strongly depends on the annealing conditions, surface preparation, and the material’s history.

To better understand these phenomena, niobium samples was annealed under ultrahigh vacuum (Mid-T baking) with plasma treatment to investigate surface contamination with in-situ heat treatment and XPS analysis.

Speaker: Chahinez Boutelaa (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

16:00 In-Vacuum Pulsed Wire Technique

The pulsed wire technique has been used in the past mainly for trajectory control
in wigglers and undulators. Including dispersion and pulse width corrections improved significantly the quality of these measurements, especially for short period and/or long undulators. Recent approaches use the direct measured pulse instead of the model of an idealized rectangular pulse and the impact of tiny, but relevant induced currents by the wire oscillation is understood. The in-vacuum pulsed wire system at European XFEL will be part of the SUNDAE2 (Superconducting UNDulAtor Experiment) horizontal test stand. In this contribution we report on the progress made and first measurements on a 5 m long permanent magnet undulator with 40 mm period. The aim is to be a true alternative for Hall-probe measurements.

Speaker: Michael Ronniger (European X-Ray Free-Electron Laser)

16:00 In-Vacuum Undulators for BESSY II

Since 2018, the BESSY II storage ring has operated a cryogenic permanent magnet undulator (CPMU), which was developed and constructed in-house. With a period of 17 mm, CPMU17 was the first in-vacuum undulator to be installed at BESSY II. Another CPMU (CPMU20) and the world’s first in-vacuum APPLE II undulator (IVUE32) are currently under construction and will be installed at BESSY II within the next few years.
To meet the needs of its diverse and ever-evolving user community, BESSY II has pioneered innovative operating modes, such as low-alpha and TRIBS, in addition to the hybrid mode. These special operating modes are based on phase space manipulation, which is enabled by the accelerator lattice's great flexibility and tight tolerances for the insertion devices. Accordingly, there are also tight tolerances on in-vacuum IDs. This paper discusses some of the main challenges, as well as the key developments and strategies, involved in meeting tolerance requirements.

Speaker: Atoosa Meseck (Helmholtz-Zentrum Berlin für Materialien und Energie, Johannes Gutenberg University Mainz)

16:00 Influence of wall plug efficiency from solid state power amplifier for particle accelerators on total costs of ownership

The overall efficiency of rf power amplifier has a crucial impact on the operating costs, especially for high power systems and when the total installed power is high. There are ways for optimizing the overall efficiency by design and by operational settings. Here we present a way to optimize the efficiency, and therefore directly the operating costs, by adaption of the drain voltage. Furthermore, we illustrate how the power consumption changes in dependence of the system efficiency at the example of our established system design.

Speaker: Marcus Lau (TRUMPF Huettinger GmbH)

16:00 Infrastructure Worksite Coordination : lessons learned from the HL-LHC case study

The High-Luminosity Large Hadron Collider (HL-LHC) project at CERN is a major upgrade LHC’s today instantaneous luminosity by a factor of five and today total integrated luminosity by ten. This involves extensive new infrastructure, including underground galleries, access shafts, and surface facilities, pushing accelerator technology beyond current limits. Managing this complexity requires centralized coordination through a worksite hub that enables real-time communication, adaptive planning, and stakeholder support from conception to commissioning. A combined top-down and bottom-up planning approach ensures alignment with long-term objectives while addressing operational challenges. Dedicated planning tools support milestone tracking, resource management, and coordination of activities. Operational efficiency relies on safety, schedule adherence, and rapid response to technical issues. This paper highlights the importance of flexible on-site coordination, integrated planning, and advanced monitoring tools for large-scale projects. The approach demonstrates strong adaptability, reactivity, and collaborative problem-solving.

Speaker: Thomas Bauler (European Organization for Nuclear Research)

MOP7147_edited_version.pdf

16:00 Initial Design of a Lumped Inductance Kicker for the FCC-ee

CERN is working towards a new, larger circular collider complex, the Future Circular Collider (FCC-ee), with a perimeter of 90.7 km. This paper addresses some of the challenges associated with beam-transfer equipment. The FCC-ee requires numerous kicker systems for beam disposal and transfers from injectors to the main collider ring. To standardise hardware parameters across machines and reduce the variety of beam-line components, this work proposes a lumped-inductance kicker magnet for multiple systems. To adapt the design for different purposes within the FCC complex, only the number of modules is adjusted to achieve the required deflection, while maintaining a low voltage for each module to enable operation outside the vacuum. This common design offers significant advantages for spares, maintenance, production, and machine protection. Initial design-study results from numerical simulations of the beam-line element are presented, along with system-level options for integration with the FCC-ee accelerator.

Speaker: Sen Yue (European Organization for Nuclear Research)

MOP7129_edited_version.pdf

16:00 Injection background studies at FCC-ee

The electron–positron Future Circular Collider (FCC-ee) is a proposed high-energy lepton collider designed to achieve unprecedented luminosity and precision in the study of fundamental particle physics. To fully exploit this potential, it is crucial to control beam-induced experimental backgrounds to ensure safe operation and optimal detector performance. This is particularly challenging due to the complex operational requirements; for example the top-up injection process that generates unavoidable losses at each injection while detectors are taking data. The present baseline scheme foresees a fast bump in the injection region that affects the full circulating beam, leading to beam-halo losses. In this paper, we study these losses, from their sources up to the detector using a multi-step simulation framework, employing multi-turn tracking followed by Monte-Carlo shower studies and detector occupancy analyses, to evaluate their potential impact on experimental detector performance.

Speaker: Giulia Nigrelli (Sapienza University of Rome, Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, European Organization for Nuclear Research)

MOP1050_edited_version.pdf

16:00 Insights from LHC Bunch-by-Bunch Performance Analysis

In the Large Hadron Collider (LHC) the multi-bunch protons beams of collide at the four main interaction points along its 26.7~\unit{\km} circumference. While global beam parameters provide a macroscopic view of machine performance, a detailed bunch-by-bunch analysis offers a unique “radiograph” of the underlying beam dynamics and collective effects. In this work, we present a comprehensive study of bunch-by-bunch performance indicators, including luminosity, emittance evolution, and beam intensity decay, using data acquired during Run 3 operation. The analysis combines information from high-resolution beam instrumentation—such as the Fast Beam Current Transformer (FBCT), the Beam Synchrotron Radiation Telescope (BSRT), and luminosity monitors from the LHC experiments—with complementary simulation studies from the Luminosity Model.
Clear and reproducible patterns are observed across bunch trains, revealing the impact of long-range beam–beam interactions, electron-cloud effects, and bunch-dependent variations. The results demonstrate the potential of bunch-by-bunch data analysis in disentangling complex interdependent effects and contribute to a deeper understanding of the LHC beam dynamics, paving the way for improved modeling for performance optimization in preparation for the High-Luminosity LHC era.

Speaker: Ilias Efthymiopoulos (European Organization for Nuclear Research)

16:00 Integrated HTS CCT magnet and beam pipe : a proposal for the FCC-ee final focus quadrupole QC1L/R1

High Temperature Superconductors (HTS) and Canted Cosine Theta (CCT) technologies have been extensively studied in recent years, particularly for high-field accelerator magnets. Their application to next-generation particle accelerators is especially promising. This article presents the combination of these two technologies for the FCC-ee Final Focus (FF) quadrupole QC1L/R1, including its integration within the Machine-Detector Interface (MDI).

We detail the specific design, mechanical specifications, and manufacturing process—driven by the coil’s significant curvature angle—as well as the cryogenic test strategy and results. Additionally, we describe the design of a cooled beam pipe adapted to the magnet and cryostat constraints.

Speaker: Matthieu Marchand (Institut National de Physique Nucléaire et de Physique des Particules)

MOP7074_edited_version.pdf

16:00 Integrated simulation of Compton backscattering and beam–beam effects for bunch intensity control in FCC-ee

Precise regulation of the bunch population in FCC-ee is required to maintain the charge imbalance between collision bunches within the 3-5% tolerance that preserves beamstrahlung limits, bunch-length stability, and avoids flip–flop behaviour. Laser-driven Compton backscattering (CBS) has been proposed as an active actuator for bunch-by-bunch intensity control.
An Xsuite-based simulation framework is employed to track the beam over many turns, while the bunch population is continuously updated according to the CBS-induced particle removal. The modified bunch intensity is then propagated into the beam–beam interaction model, allowing the resulting impact on beam parameters and overall stability margins to be quantified.

Speaker: Illya Drebot (Istituto Nazionale di Fisica Nucleare)

MOP1076_edited_version.pdf

16:00 Integrating FPGA into epics for on-the-fly scan control at the TPS 35A beamline

The growing demand for high-throughput XAS measurements at next-generation synchrotron light sources makes On-the-Fly Scan indispensable. Original software-based implementations improved efficiency but were limited by slow PC communication (~8 Hz) and soft-trigger jitter (<10 ms), restricting precise synchronization for multi-axis, non-linear trajectories and long-range energy scans.
This work introduces a hardware-level fly-scan architecture that deeply integrates a Field-Programmable Gate Array (FPGA) into the EPICS control system at the TPS 35A beamline. Acting as a hardware acceleration core, the FPGA eliminates OS-induced latency and leverages high-speed parallel processing to achieve deterministic control. The system synchronously encapsulates ADC detector data, precise time tags, and high-speed position encoder feedback with nanosecond-level precision, enabling real-time trajectory compensation. This capability supports nano- to micro-second–scale measurements, opening new opportunities for time-resolved XAS. By replacing software delays with hardwired logic, this EPICS-FPGA paradigm delivers a standardized, stable, and highly efficient XAS measurement platform, critical for photon dose-sensitive samples. It fully realizes the hardware upgrade envisioned by previous software-based solutions, setting a new benchmark for high-performance beamline control.

Speaker: Cheng-Yuan Lin (National Synchrotron Radiation Research Center)

MOP6685_edited_version.pdf

16:00 Integration of a GaN HEMT Solid-State Driver Amplifier for the 10 MHz RF System of the CERN PS

The progressive obsolescence and the discontinuation of vacuum tube production are driving the transition towards solid-state alternatives in RF acceleration systems. In the 10 MHz RF system of the Proton Synchrotron (PS) at CERN, the discontinuation of a specific tetrode model used in the amplifier chain has motivated the evaluation of solid-state technology as a potential replacement. In particular, amplifiers based on Gallium Nitride High Electron Mobility Transistors (GaN HEMTs) are being considered due to their inherent radiation tolerance. For this purpose, a prototype driver amplifier based on the GaN technology has been built. This contribution presents the different development steps of this prototype, as well as its integration into the 10 MHz RF system. This includes a system-level description of the RF system and of the constraints associated to the integration of such a prototype, followed by its hardware description and qualification process. This qualification was carried out in two steps: firstly through RF measurements without beam, and secondly with a characterization of the system with high-intensity proton beams, under normal operating conditions.

Speaker: Mathieu Taquet (European Organization for Nuclear Research)

MOP7056_edited_version.pdf

16:00 Integration of X-Ray Diagnostics into Fast Orbit Feedback for Local Source Stabilization at NSLS-II

We present an accelerator-based X-ray beam stabilization approach that integrates X-ray beam position monitor (XBPM) signals into the fast orbit feedback (FOFB) system at NSLS-II. A high-speed electrometer and fiber-optic data link were developed to transmit XBPM position data to the storage-ring feedback controller at a 10 kHz rate. On the accelerator side, the XBPM signal is incorporated into the FOFB infrastructure as a virtual beam position monitor, allowing photon beam motion to be corrected through the electron beam orbit using fast corrector magnets. Experimental tests demonstrate suppression of dominant beamline vibration peaks near 27 Hz and 120 Hz when the feedback is enabled. These results demonstrate the feasibility of integrating photon diagnostics into accelerator feedback systems for improved X-ray beam stability and motivate the development of unified photon–electron feedback architectures for routine operation.

Speaker: Guimei Wang (National Synchrotron Light Source II)

MOP6375_edited_version.pdf

16:00 Interplay of beam-beam and linear coupling on luminosity calibration

With the LHC reaching percent-level luminosity precision, controlling systematic biases in luminosity calibration has become essential. Among these, the interplay between linear coupling and beam–beam interactions can alter the measured luminosity and consequently the visible cross-section during van der Meer (vdM) scans. The combined effect of nonlinear beam–beam forces and linear coupling makes the transverse charge distribution non-factorisable, impacting the luminosity overlap integral used for absolute calibration.
In this work, transverse luminosity density profiles, luminosity, and visible cross-section have been systematically characterised to quantify the influence of coupling and beam–beam interactions for different particle distributions, including Gaussian and q-Gaussian beams. Simulations incorporating a simplified model of local coupling in the interaction regions, together with beam–beam effects, were performed to evaluate the impact of both local and global coupling across various vdM configurations.
The results deepen our understanding of coupling–beam-beam interplay in the LHC and hadron colliders more broadly, reveal potential deviations from classical Gaussian-based assumptions, and motivate future studies of vdM luminosity behaviour that include more realistic and complex beam-dynamics effects.

Speaker: Tatiana Pieloni (École Polytechnique Fédérale de Lausanne)

16:00 Inverse modeling of spatially coherent random vibrations for assessing impact on particle beam dynamics in circular accelerators

Vibrations cause emittance growth, beam misalignment at the interaction point, and particle loss, limiting accelerator performance. Ground motion and technical noise are characterized by absolute power spectral density (PSD) and spatial correlation. Mechanical support resonances, which amplify these effects, are determined via transfer functions. A method to generate random displacements from these vibration characterizations was developed using one- and two-dimensional inverse Fourier transforms. The generated displacements accurately reproduced the input PSD spectra and spatial correlation, as verified by Welch's estimation. As a demonstration, the displacements were applied to X-suite beam dynamics simulations of the FCC-ee booster lattice to assess emittance growth and beam offsets. The method enables iterative optimization of mechanical supports and beam transport systems to minimize vibration impacts.

Speaker: Purinut Lersnimitthum (Université Paris-Saclay)

16:00 Investigation of diagonal-cut plane BPM performance in the CSNS RCS

Diagonal-cut plane Beam Position Monitors (BPMs) are used to measure the transverse position of the proton beam in the Rapid Cycling Synchrotron (RCS) at the China Spallation Neutron Source (CSNS). Significant transverse beam position offsets were observed at several locations along the RCS. These offsets are potentially attributable to abrupt changes in the cross-section of the upstream and downstream vacuum ducts, BPM calibration constants determined at a single frequency on the calibration system, and limitations in the position calculation algorithm. To assess the impact of the sudden changes in beam duct aperture, numerical simulations were performed. Additionally, BPMs were recalibrated on a test bench to evaluate the influence of abrupt cross-sectional changes in the BPM and vacuum ducts on the observed offsets at different frequencies.

Speaker: Muhammad Abdul Rehman (Institute of High Energy Physics)

MOP6621_edited_version.pdf

16:00 IP-SAFE for the production of radiopharmaceutical isotope Ac-225

The global adoption of targeted alpha therapy (TAT) using actinium-225(²²⁵Ac)-labeled radiopharmaceuticals is rapidly expanding, driving an urgent need to scale up ²²⁵Ac production and improve supply reliability. Among potential production methods, accelerator-based high-energy proton irradiation of thorium-232(²³²Th) targets via the ²³²Th(p,x)²²⁵Ac reaction represents a promising and sustainable approach. However, achieving large-scale ²²⁵Ac production through this route requires addressing key technological challenges, including the development of high-power proton beams (100–150 MeV) and robust targetry systems.
To address these challenges, the Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS), is constructing a dedicated demonstration facility—the Isotope Pharmaceutical production platform based on Superconducting Accelerator Facility for Effective therapy (IP-SAFE). Powered by a state-of-the-art Superconducting Radio Frequency (SRF) linear accelerator, this advanced facility will deliver a high-performance 115 MeV Continuous Wave (CW) proton beam with an intensity of 0.5–1 mA to irradiate ²³²Th targets. This paper provides an overview of the IP-SAFE project, highlights the recent progresses.

Speaker: Liangting Sun (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 IPAC’25 PRE session-report: fostering a productive research environment in the accelerator community

The Productive Research Environment (PRE) session at IPAC’25 explored practices and challenges in fostering sustainable and motivating research environments in the accelerator community. A preliminary survey of 51 managers and leaders revealed high levels of motivation during the early career stage, but also highlighted concerns regarding staffing shortages, budgetary constraints, and the long-term career prospects of young researchers.　Session presentations addressed career experiences, sustainable institutional models, and survey-based perspectives across different career stages. The subsequent panel discussion engaged additional senior leaders and covered key themes including human resources and diversity, leadership development, mentorship and supervision, and intergenerational collaboration. The session concluded that clear goals, adequate resources, inclusive cultures, structured leadership and mentoring, and effective knowledge transfer are essential for productive research environments. Despite current limitations, the strong motivation of young researchers offers a promising foundation. Building on this, PRE aims to expand its surveys and sustain dialogue at future IPAC meetings to strengthen human resource capacity and foster diversity across the global accelerator community.These findings and perspectives will be reported and further discussed at the conference.

Speaker: Yoichi Sato (Japan Proton Accelerator Research Complex)

MOP8620_edited_version.pdf

16:00 ISOLDE Beam Dumps Replacement and Sustainability (IBDRS) project: A challenging consolidation, from buried dumps to flexible access

The CERN ISOLDE Facility is a premier Radioactive-Ion-Beams (RIBs) facility using the ISOL (Isotope Separation On-Line) method to provide RIBs at energies from 30 keV to 10 MeV/u for a large variety of experiments. Recognized worldwide for its significant contributions to nuclear physics, ISOLDE now faces the challenges of its aging infrastructure. As a consequence, a comprehensive improvement program has been launched to enhance the capabilities and capacities of the facility as well as to ensure that several systems meet modern radiation safety standards. A critical component of the program is the replacement of the two beam dumps that absorb the fraction of the proton beam that does not interact in the RIBs production targets. This contribution details the aspect of the project that includes the removal of the two dumps and their associated shielding (soil and shielding blocks), the design of the new beam-dump cores to cope with the higher beam power of the proton driver in the future, as well as the construction of the infrastructure hosting the new systems.

Speaker: Tristan Calvet (European Organization for Nuclear Research)

16:00 KIT superconducting undulator and magnet developments - overview and state of the art R&D on HTS technology

Undulators are widely used in synchrotron storage rings and free-electron laser facilities. With the advent of low-temperature superconductors (LTS), a new generation of superconducting undulators (SCUs) emerged, including the recent new THz LTS undulator for FLUTE. At KIT, state-of-the-art magnetic and cryogenic measurement capabilities — provided by the Magnet and Cryogenics Facilities (MCF) and the Accelerator Technology Platform (ATP) — form a foundation for the development and characterization of these systems.

Building on this experience, KIT is now advancing magnets and undulators based on high-temperature superconductors (HTS), aiming for compact, sustainable, energy- and resource-efficient solutions. These activities are driven by in-house research and providing the full value chain of HTS technology from tape development via structuring to prototypes and tests in real-world environments at KIT.

In this contribution, we provide an overview of our current developments and the supporting experimental infrastructure.

Speaker: Dr Bennet Krasch (Karlsruhe Institute of Technology)

MOP7120_edited_version.pdf

16:00 LACCS: The High-Performance Integrated Intelligent Control System in the HIAF

The large-scale accelerator complex control system, LACCS, based on the self-developed high-speed and high-security communication protocol, CVLink, has been successfully deployed at HIAF (High Intensity heavy ion Accelerator Facility), a major national science and technology infrastructure in China. It has integrated the control of about 330,000 variables corresponding to 141 beam dynamics and approximately 2,000 hardware devices across the entire facility, as well as online storage of tens of billions of records. The system plays an important role in reducing the first beam commissioning time in HIAF to several hours, comprehensively verifying the LACCS ecosystem, which consists of embedded hardware control, big data computing and storage, user interface development toolkits, and artificial intelligence. Taking advantage of its capability to integrate all facility data and monitor all variables, the LACCS will make HIAF evolve from conventional beam commissioning toward unmanned operation. In the future, HIAF will adopt a large model as its brain to interpret knowledge bases and process all operation data online, while traditional optimization algorithms and machine learning models will serve as its eyes and hands to interact with the facility. All daily operation of HIAF will be conducted by an AI cluster to realize intelligent beam delivery.

Speaker: Jie Liu (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Large scale production of amorphous carbon coatings for the new beam screens of the HL-LHC project

The new beam screens for the High Luminosity LHC (HL-LHC) will be coated with a low Secondary Electron Yield (SEY) amorphous carbon (a-C) thin film to suppress electron multipacting and reduce heat loads to the cryogenic system. The production will cover 40 beam screens for the new superconducting magnets of the inner triplets in LHC interaction regions 1 (ATLAS) and 5 (CMS), as well as 24 beam screens for the drift line of the cryomodules housing the CRAB cavities.
This contribution presents the implementation of a large-scale coating facility dedicated to the deposition of a-C films on the various HL-LHC beam screens, adaptable to different geometries and lengths up to 14 meters. The rationale behind the chosen coating technology and process parameters is discussed, with emphasis on adhesion optimization, SEY minimization, and production throughput to meet the HL-LHC schedule. We report on the current status of the production campaign, including quality assurance statistics, and highlight the main challenges encountered together with the solutions adopted.

Speaker: Mr Bernard Henrist (European Organization for Nuclear Research)

MOP7175_edited_version.pdf

16:00 Large-scale helium refrigeration cryogenic systems costing for superconducting particle accelerators such as the FCC-ee

Large-scale helium refrigeration cryogenic systems are a key element, essential to the safe and reliable operation of particle accelerators using superconducting devices such as radio-frequency cavities or magnets. The long-term success of the LHC operation with an outstanding physics production to date paves the way towards the High-Luminosity LHC (HL-LHC) upgrade to be operated until the early 2040s, after which it could be followed by the Future Circular Collider (FCC). Such large-scale projects, requiring a significant amount of cryogenic cooling capacity to be installed, pose the question of the cost estimation methodology to be employed, as the cryogenic system represents a non-negligible fraction of the total capital, operation & maintenance cost of the facility. Capitalizing on the experience of the LHC project, then on its recent HL-LHC upgrade, the existing CERN methodology was updated with the latest available industrial indexation, thus allowing the cost of the FCC cryogenic system to be assessed. This paper reports on the approach used to estimate the cost of the FCC cryogenics, refining the method adopted at the time of the LHC project. It considers the evolution of material and labour costs over the past two decades, studies the updated economics of 4.5 K and 1.8 K helium refrigeration, and presents the strong impact of the cryogenic distribution system. It also identifies and proposes ways for improving the capital, operation & maintenance expenditure.

Speaker: Laurent Delprat (European Organization for Nuclear Research)

MOP7087_edited_version.pdf

16:00 Laser wire scanning for 2D electron beam size measurement in Slant-Scattering Mode at SLEGS

The precise measurement of electron beam profiles is important for accelerator diagnostics. Laser wire scan is a classical and practicable method for beam size measurement which is based on Laser Compton scattering. Conventional laser wire scan methods require two separate scans: one for the horizontal and one for the vertical size. However, the slant-scattering geometry of Shanghai Laser Electron Gamma Source (SLEGS) beamline station enables the simultaneous projection of both dimensions onto a gamma-ray intensity profile, allowing both sizes to be extracted from a single scan. To enable this extraction, we developed a novel analysis approach. This approach involves numerical integral modeling of the slant-scattering process with a genetic algorithm to optimize the beam parameters. Using this method, we successfully measured the transverse electron beam size at the interaction point in the slant-scattering mode of SLEGS.

Speaker: ZhenWei Wang (Shanghai Institute of Applied Physics, Chinese Academy of Sciences)

MOV6602_edited_version.pdf

16:00 Latest advancements of the test-particle Monte Carlo code MolFlow

MolFlow is a test-particle Monte Carlo code for ultra-high vacuum simulations, primarily intended for use in the field of particle accelerators. This contribution gives an overview of updates made to the code in recent years. The graphical user interface has been improved and a new feature has been added for extracting simulation results along user-defined 3D paths. Additionally, the code can now count the number of particles present on a surface at a specified time. Furthermore, the calculation of particle residence time (sojourn time) has been updated to allow for temperature variations during a particle's residence on a surface. This enables simulations of surface decontamination through heating (bakeout). Finally, MolFlow can now simulate particle collisions with static background gases using the hard-sphere collision model.

Speaker: Petar Trifunović (European Organization for Nuclear Research)

MOP7105_edited_version.pdf

16:00 Latest measurements of magnetic noise in the LHC tunnel

The magnetic coupling between nearby accelerator rings can introduce unwanted perturbations to beam dynamics, representing a potential concern for future colliders such as the High-Luminosity Large Hadron Collider, or multi-ring facilities such as the Future Circular Collider or the Muon Collider complex. To explore and benchmark this effect, dedicated tests were performed to study the electromagnetic interplay between the SPS and the LHC. Controlled excitations in the SPS were applied while monitoring the response of the beams in the LHC using high-precision instrumentation. Clear signatures of coupling were observed, providing valuable input for the validation of simulation models and for improving the understanding of magnetic field propagation between accelerator infrastructures. In this paper, the results of these measurements are presented and discussed.

Speaker: Guido Sterbini (European Organization for Nuclear Research)

MOP1064_edited_version.pdf

16:00 LEnuSTORM: A low-energy muon storage ring for neutrino cross-section measurements

The LEnuSTORM (low-energy neutrinos from stored muons) is a proposed facility that enhances the performance of the ESSnuSB* (European Spallation Source Neutrino Super Beam) project by measuring neutrino cross sections in the energy range 200-600\,MeV, where data is largely missing. The facility utilizes a 1.25\,MW proton beam from the European Spallation Source linac, which is compressed in an accumulator into 1.2\,µs pulses and directed at a granular titanium target embedded in a horn. Pions collected by the horn are transferred and injected into a racetrack-shaped storage ring where they decay and emit muons that will be stored in the ring for a few tens of turns. The neutrinos emitted in the muon decay in one of the straight sections will travel to a water Cherenkov detector, where the interactions are monitored.

At LEnuSTORM, the beam is large and very divergent, and thus difficult to contain. The ring design presented in this paper uses iron-dominated magnets to reduce complexity, and a compact FODO lattice with strong focusing to maximize neutrino production by allowing a large transverse acceptance. However, the design pushes fringe-field effects beyond the linear regime and requires a paraxial expansion with higher-order terms, introducing resonances and reduced dynamic aperture. We present here a design that aims at balancing the transverse and momentum acceptance with the dynamic aperture, to maximise neutrino production.

Speaker: Ting Wing CHOI (Uppsala University)

MOP1098_edited_version.pdf

16:00 Leveraging low-cost sensors and machine learning for pump anomaly detection in accelerator facilities*

The reliability of cooling systems is critical for removing substantial amounts (in megawatts) of waste heat from numerous high-power accelerator components (e.g., magnets, RF structures, power supplies) and beamline components*. Reliance on manual inspection of hundreds of pumps is inefficient and increases the risk of costly component damage and unplanned downtime. This study introduces a real-time method for automated vibration monitoring of pumps designed to help transition facility operations from reactive to predictive maintenance. Our approach integrates (i) affordable vibration sensors** and (ii) machine learning models *** for anomaly detection. We have deployed vibration sensors on the Bunch Lengthening System (BLS) Helium and water pumps, where Linux nodes aggregate and preprocess the hourly collected data. To support operational decision-making, a web-based diagnostic platform is being developed, offering real-time visualization of vibration trends against weekly baseline data and generating Short-Time Fourier Transform (STFT) spectrograms for detailed frequency analysis. Additionally, the web platform will show hourly inferences from the machine learning models on the data stream, autonomously detecting spectral anomalies indicative of mechanical faults. The integration of scalable edge data collection, advanced visualization, and unsupervised deep learning will provide a vital safeguard for maintaining operational readiness in particle accelerators.

Speaker: Joseph Calvey (Argonne National Laboratory)

MOP6303_edited_version.pdf

16:00 LHC machine configuration evolution over Run 3 for maximised performance and inner triplet lifetime

Initially planned to start in 2021 and to end up in 2024, the third exploitation period of the LHC (Run 3) started in 2022 and was extended by two years to fit the adjusted schedule of the High Luminosity LHC (HL-LHC) project. Run 3 was not only marked by the exceptional performance of the machine (with 125 1/fb delivered to the two high luminosity experiments ATLAS and CMS, both in 2024 and 2025). Run 3 was also used as a unique opportunity for the transition between the LHC and the HL-LHC, both in terms of optics and beam parameters, in particular with the smallest beta* of 15 cm put in operation so far, and the highest bunch charge of 1.8e11 protons/bunch now regularly used in operation. In order to make this transition as adiabatic as possible, the machine configuration was modified year by year, not only to profit as much as possible from the incremental increase of the bunch charge available at the exit of the injector chain, but also to mitigate the radiation dose deposited in the inner triplets of the two high luminosity experiments ATLAS and CMS. This paper describes the main changes applied to the machine configuration over this period, together with the motivations.

Speaker: Stephane Fartoukh (European Organization for Nuclear Research)

MOP1057_edited_version.pdf

16:00 LHC magnetic model revisited: beam-based measurements and machine reproducibility at injection

The harmonic components of the LHC superconducting magnets exhibit a characteristic decay at low-field, primarily caused by current redistribution within the superconducting cables. This redistribution leads to variations in the multipolar components of the magnetic field, which in turn induce changes in the beam tune and chromaticity. To counteract these effects, a feed-forward compensation system applies predicted corrections during the injection phase, ensuring stable beam conditions. In this work, we employ beam-based measurements to reassess the FiDeL (Field Description of the LHC) magnetic model, which provides parameterizations of the field harmonics as functions of time, current, and magnet history. The goal is to evaluate both the accuracy and reproducibility of the FiDeL-based corrections. The analysis reveals systematic deviations between model predictions and beam observations, indicating limitations in the current implementation.

Speaker: Jorg Wenninger (European Organization for Nuclear Research)

MOP1019_edited_version.pdf

16:00 LHC operation with oxygen and neon ions

During summer 2025, the CERN Large Hadron Collider operated for the first time with oxygen and neon ion beams. Three different machine configurations---with collisions of p‑O, O‑O, and Ne‑Ne and with varying beam energies and optics---had to be commissioned and exploited for physics operation during the eight days allocated. This short run was challenging because of its very tight schedule, the novel modes of operation, and new beam‑physics effects such as transmutation of oxygen and neon nuclei into other nuclei with the same magnetic rigidity. In spite of these challenges the run was very successful with the luminosity targets set by the LHC experiments fully met and, in most cases, even exceeded by large factors. In addition, time was allocated for machine studies, resulting in the first LHC data on crystal channeling with O and Ne ions. In this article we give a general overview of the LHC machine configuration, operational challenges, and experience during the run, as well as the achieved performance and the key contributors to the successful outcome. The results demonstrate the LHC’s flexibility for mixed‑species operation and give valuable input for future ion

Speaker: Reyes Alemany-Fernandez (European Organization for Nuclear Research)

16:00 Linear imperfection and orbit correction scheme for the PERLE accelerator

PERLE is a multi-turn Energy Recovery LINAC, currently under construction at IJCLab in Orsay (France). It is designed to accelerate electrons of 20 mA beam current to an energy of 250 MeV through three accelerating followed by three decelerating passes to dump the beam at injection energy (7 MeV). The first order lattice design has emerged. Therefore, assessing the sensitivity of the optics to linear imperfections is a crucial step toward stable operation. This work investigates the impact of quadrupole misalignments on the beam orbit in both planes, accounting for the presence of horizontal and vertical dispersive sections in PERLE. The resulting orbit distortions are used to identify the most critical locations for diagnostics and correction elements. A correction strategy based on BPM–corrector pairs is implemented using the BMAD framework, and the achievable orbit restoration is evaluated with adequate correction strengths.

Speaker: Rasha Abukeshek (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

MOP1110_edited_version.pdf

16:00 LIPAc RF system: on the versatile use of photomultipliers

Modern photomultipliers (PMs) are affordable, highly sensitive, easy to operate, compact, and sufficiently robust for demanding accelerator environments. In systems such as the Linear IFMIF Prototype Accelerator (LIPAc) in Rokkasho, Japan, whose radiofrequency (RF) subsystem delivers over 2 MW of RF power distributed among all the accelerating cavities, these characteristics make PMs particularly effective for monitoring components prone to multipacting and micro-discharge. The light produced by these phenomena is detected even at very low levels, enabling detailed investigation and fast triggering of interlocks to prevent damage. At LIPAc, the superconducting RF (SRF) accelerator currently being commissioned is fully equipped with PMs. PMs have also been successfully used in a temporary test bench* and in lightweight setups to assess the attenuation of aging optical fibers. Finally, prospects for upgrading the existing RF quadrupole (RFQ) arc detector will be presented.

Speaker: Jean-Pierre Adam (CEA Gramat)

MOP7054_edited_version.pdf

16:00 Longitudinal phase space diagnostics for the AGS

The Collider-Accelerator Department (C-AD) maintains and operates an injector complex that provides beams for the Relativistic Heavy Ion Collider (RHIC) and the future Electron-Ion Collider (EIC). Beams traveling in accelerator rings are grouped in bunches, where their profiles can be measured and displayed by a Wall Current Monitor (WCM). By analyzing those WCM signals, conclusions can be made about the beam quality, and necessary tuning can be performed accordingly. Meanwhile, it will be very helpful to have the beam property parameters available while doing beam experiments, such as the longitudinal emittance, momentum spread, bunch length, etc. In this work, we present such a software tool that will process and publish those parameters in real time, based on live machine data and WCM signals. Those parameters will also be logged to the system and will be available for later retrieval and analysis.

Speaker: Kiel Hock (Brookhaven National Laboratory)

MOP6393_edited_version.pdf

16:00 Low-energy injection study for TPS booster ring during Linac modulator degradation

In early 2025, Linac modulator 3 at the Taiwan Photon Source (TPS) exhibited signs of performance degradation. To reduce electrical stress and prevent an unplanned failure during user operations, BR injection feasibility was evaluated at 130 MeV, 140 MeV, and the nominal 150 MeV. Two compounding mechanisms limit low-energy injection efficiency: increased geometric emittance from the Linac, and degraded BR power supply waveform reproducibility at the earlier injection point on the ramp, which reduces the dynamic aperture. At 130 MeV, the mean BR current of 0.168 mA cannot satisfy the 5-second top-up window. At 140 MeV, a mean of 0.342 mA meets the >0.3 mA operational criterion, and this 140 MeV rescue mode maintained uninterrupted user service throughout the modulator degradation period.

Speaker: Wei-Yu Lin (National Synchrotron Radiation Research Center)

MOP6690_edited_version.pdf

16:00 Luminosity Loss from Ground Motion in the FCC-ee: MDI and Arc Quadrupole Vibration Studies

Ground motion can significantly impact beam stability in the FCC-ee, potentially degrading luminosity at the interaction point (IP). The study models vibrations of accelerator components, including the interaction region cryostats at the Machine Detector Interface (MDI) and the quadrupole girders in the arcs. Using measured power spectral densities (PSDs) and component-specific transfer functions, realistic time-dependent displacement signals are generated and applied in Xsuite particle tracking simulations. Analysis of beam centroid motion at the IP and the relative transverse offset between colliding beams quantifies the resulting luminosity degradation. These results indicate that ground-induced motion may necessitate dedicated feedback systems for both orbit correction and luminosity stabilization. Findings inform the design of vibration mitigation strategies and feedback strategies for the FCC-ee.

Speaker: Dr Mael Le Garrec (Laboratoire d’Annecy de Physique des Particules, Centre National de la Recherche Scientifique, Institut National de Physique Nucléaire et de Physique des Particules)

16:00 Machine learning-assisted calibration of the accelerator simulator HPSim

Manually calibrating the HPSim simulator to the LANSCE accelerator is time-intensive and demands substantial domain expertise. In this work, we investigate the use of machine learning (ML) to automate much of the calibration process and substantially reduce tuning time. Specifically, our focus is the calibration of the front-end of the accelerator, which involves obtaining the amplitudes and phases of the pre-buncher, main buncher and tank 1 of the drift tube linac. To get empirical data of the accelerator, we use current-phase curves obtained from absorber/collectors, both with the pre-buncher on and off. We derived features from the curves, such as standard deviation of each or average distance between them, which are then trained on ML models. By combining classical ML methods—gradient-boosted decision trees and random forests—with a state-of-the-art transformer model, we achieve a significant speed-up of the calibration process, from about a month of human expert labor to 2-3 days of mostly computational processing.

Speaker: Christopher Leon (Los Alamos National Laboratory)

MOP6320_edited_version.pdf

16:00 Machine Learning-Based Orbit Correction in the RCS of CSNS

The rapid cycling synchrotron (RCS) of The China Spallation Neutron Source (CSNS) accumulates and accelerates the injection beam from 80 MeV/300MeV to the energy of 1.6 GeV and then extracts the high energy beam to the target. During each cycle of the RCS ring, beam positions at the same BPM vary over time due to energy and mode transitions. Traditional orbit correction averages turn-by-turn (TBT) data over 512 turns, producing 20 points over 20 ms, and applies the response matrix method to correct each orbit independently. However, this approach overlooks temporal orbit variations and inter-orbit correlations, limiting correction accuracy. To address these limitations, we implemented a machine learning-based orbit correction system. Using raw BPM orbit data as inputs and corrector changes as outputs, the model learns the relationship between orbit deviations and correction actions. Results demonstrate that this method effectively corrects time-varying orbits, achieving significantly improved performance. This paper presents a detailed overview of the machine learning-based approach.

Speaker: Xiaohan Lu (Institute of High Energy Physics)

MOP6603_edited_version.pdf

16:00 Machine-learning surrogate modeling of the RAON LEBT beamline

We present a machine-learning surrogate model for the RAON LEBT that enables fast prediction of beam centroids at multiple diagnostics. A dataset of TRACK simulations spanning relevant steering-magnet and electrostatic-quadrupole settings is used to train fully connected neural networks. The surrogate model reproduces the underlying beam dynamics with high accuracy while providing orders-of-magnitude faster evaluation. This approach supports rapid orbit studies, optimization, and data-driven beam control in the RAON front-end transport system.

Speaker: Chong Shik Park (Korea University Sejong Campus)

MOP6703_edited_version.pdf

16:00 Machine-Learning–Assisted Bayesian Uncertainty Quantification for Accelerator Digital Twin Modeling and Control

Digital twins of particle accelerators are increasingly used for experiment planning, machine studies, and model‑based control. Achieving high‑fidelity predictions requires knowledge of machine properties that are difficult to measure directly, such as magnet alignments, transfer function variations, nonlinearities, and stray fields. In this work, we introduce parameterizations to capture these effects and employ Bayesian inference to estimate their values and uncertainties by calibrating a digital twin to orbit response measurements from the AGS Booster at Brookhaven National Laboratory. A machine‑learning emulator trained on a perturbed ensemble of Bmad simulations enables computationally efficient sampling of the high‑dimensional posterior. The resulting joint parameter distribution incorporates BPM uncertainties and provides data‑constrained variations that, when inserted back into the digital twin, significantly improve agreement with measured beam orbits while yielding uncertainty estimates on both parameters and predictions.

Speaker: Jonathan Edelen (RadiaSoft (United States))

MOP6310_edited_version.pdf

16:00 Magnets development for the ESRF-EBS injection upgrade

Projects to improve the injection performance of the storage ring and to reduce the equilibrium emittance of the booster are currently in progress at the ESRF. The booster light upgrade involves replacing 18 existing quadrupoles with 3 families (6 magnets per family) of quadrupoles featuring different yoke lengths. An upgrade of the injection zone includes the installation of a Non-Linear Kicker and the replacement or modification of several electromagnets, as well as the Septum S3. In this paper, we present the magnetic design of the booster electromagnet quadrupoles and the TL2 transfer-line permanent-magnet quadrupoles. A preliminary design of the Septum S3 and the injection-zone quadrupoles is also presented.

Speaker: Chamseddine Benabderrahmane (European Synchrotron Radiation Facility)

MOP7058_edited_version.pdf

16:00 Material-Extrusion additive manufacturing of pure copper components for accelerator vacuum systems

This report presents a carried out study of the technology and performance of three-dimensional printing for the production of parts intended for ultra-high-vacuum assemblies. The simple part geometry was taken as the reference sample. Computer-aided design and finite element method (FEM) analysis are employed to predict thermomechanical stresses and deformations at the sintering stage. Experiments were conducted, and a comparative analysis was carried out to fit the initial FEM results with the experimental ones to obtain actual mathematical models for further simulations. During the printing process, the influence of layer thickness, nozzle temperature, and printing speed on the final density, dimensional accuracy, and surface quality is systematically investigated. Using the given essential parameters new printing setup was developed to ensure the highest density. New samples were printed with the different hole diameters to assess the actual properties using different accuracy printheads. The above-mentioned research was conducted to obtain the highest density of the printed parts, which will be used to evaluate the probability of the accelerator vacuum systems’ fabrication.

Speaker: Albert Hovhannisyan (Center for the Advancement of Natural Discoveries using Light Emission)

MOP7167_edited_version.pdf

16:00 Measured and simulated channeled-halo distributions for the TWOCRYST experiment at the LHC

The TWOCRYST experiment at the CERN Large Hadron Collider provides a unique setup to study the behaviour of high-energy beam particles channelled by bent crystals. Two two-dimensional detectors in Roman Pots enable direct observation of channelled protons at energies from 0.45 TeV to 6.8 TeV. We present measured channelled-beam distributions for two bent silicon crystals with 50 urad and 7000 urad bending and compare them to combined beam-dynamics and particle–crystal interaction simulations including the full LHC lattice. The measured positions of the channelled beam is compared with beam-position-monitor data of the main beam to assess the sensitivity of the channelled-beam trajectory to realistic orbit drifts, providing key input for the requirements of future bent-crystal-based fixed-target experiments.

Speaker: Chiara Maccani (European Organization for Nuclear Research)

MOP1111_edited_version.pdf

16:00 Measurement of dielectric properties of 3D printed polymer-based materials for RF applications at 500 MHz

To include 3D printed polymer-based materials in accelerator parts the relative permittivity and the dielectric loss tangent of these materials have to be well known. A quarter wave cavity was built to measure these properties at a resonance frequency of 500 MHz by inserting a cylinder of the material under test, resulting in a frequency and quality factor shift of the cavity. By fitting the measured data to detailed CST simulations, the values of the relative permittivity and the dielectric loss tangent can be obtained. These results provide the necessary material parameters for further investigations into their use in RF accelerator components such as power couplers.

Speaker: Philipp Müller (Goethe University Frankfurt)

MOP7170_edited_version.pdf

16:00 Measuring and characterizing beam energy of a compact medical linear accelerator

Tong Chen (RefleXion Medical Inc.)
Liang Huo, Tong Li, Hao Tao, Zhen Feng, Liang Hu, Lin Zhou, Yongtao Liu (Chengdu Elekom Vacuum Electron Technology Co. Ltd)

Beam energy is an important parameter of linear accelerator. Compact linacs for medical or industrial applications are usually not equipped with beam monitors. The commonly used methods are “half value layer” (HVL) in industrial and “Percentage Depth Dose” (PDD) in medical to evaluate the beam energy of linac. However, these methods are not easily and accurately carried out, the HVL method needs big and heavy steel plates to prevent scattering x ray beams and PDD method need standard beam position and expensive 3d water tank to measure the beam energy. Most importantly, those methods cannot measure electron beam energy, but the photon distribution generated through Bremsstrahlung. This article introduced a method to measure and characterize the average electron beam energy when hitting the target by combining the external measurements and simulation beam profile results under different deflection magnetic field generated by steering coils. This method not only gives confidence in developing and operating the medical equipment but also reveals relation between beam energy and RF power settings. In addition, this paper provides energy and dose output variation across the RF pulse. This data provides guidance for proper setting of gun pulse width and timing.

MOP8304_edited_version.pdf

16:00 Mechanical Design, Virtual Assembly and Fabrication of a Compact 750 MHz IH DTL Accelerating Cavity

This contribution presents the development of a 750 MHz IH DTL cold model, a prototype of the second accelerating structure of the LINAC7 proton linac. The compact geometry required at this frequency imposes micron level tolerances, making mechanical alignment especially challenging. This constraint motivated the implementation of a virtual assembly workflow to control GD&T from the early design phase.

The mechanical design is based on CST electromagnetic simulations and particle-tracking studies, which define the Drift Tubes (DT) positioning tolerances. Drift Tubes are individually manufactured, aligned in two stacks using precision pins (±5 µm transverse, 0.01 mm axial), and integrated into a conical 1.4° cavity structure. All components were defined through MBD, and a digital twin was created using 3DCS to evaluate tolerance chains and optimize GD&T. After fabrication, CMM measurements feed a second virtual assembly using SpatialAnalyzer, allowing verification of real geometries, detection of real alignment features, and minimization of rework before physical assembly.

This methodology has enabled GD&T optimization through statistical simulations, prediction of alignment behaviour prior to fabrication, and early mitigation of assembly risks. The cold model is now being assembled, and forthcoming low-power RF tests will validate the electromagnetic performance and support the final IH DTL design.

Speakers: Amaia Villa (Tekniker), Andoni Egurrola Areta (Tekniker), Jorge Feuchtwanger (Ikerbasque)

16:00 Metal Additive Manufacturing for Accelerator Technologies (MAAT project at INFN)

The MAAT (Metal Additive Manufacturing for Accel-erator Technologies) project is a three-year INFN re-search programme launched in 2026, aimed at establish-ing Additive Manufacturing (AM) as a validated produc-tion route for high-performance accelerator components. MAAT brings together three INFN units: Legnaro (LNL), Padova (PD), and Milano LASA, combining complemen-tary expertise in superconducting RF, materials science, and advanced manufacturing. This paper reports on the activities and preliminary results during the first year of the project, covering:
1. the Design for Additive Manufacturing (DfAM) of 6 GHz cavities produced by Laser Powder Bed Fusion (LPBF).
2. the preliminary tests of the Wire Laser Additive Manufacturing (WLAM) combined with CNC ma-chining for the fabrication of a 1.3 GHz RF cavity prototype in CuCrZr.

Speaker: Oscar Azzolini (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro)

MOP7182_edited_version.pdf

16:00 Micro-fabricated photoconductive sampling devices for electron beam field measurements

Achieving high-precision, in situ measurements of electric fields is a critical challenge in ultrafast science and accelerator diagnostics. We report the progress in developing an approach using photoconductive sampling with micro-fabricated devices to map electron beam fields with unprecedented spatiotemporal resolution. This technique enables the first direct 3D vector field measurements of electron beams, offering valuable insights into collective effects such as coherent synchrotron radiation and other phenomena impacting beam quality. These low-cost, highly flexible devices present a pathway to enhancing our understanding of beam dynamics and reducing transient effects that degrade beam quality. The devices will be initially tested on the ultrafast X-ray beamline at LCLS, and could be adapted as a diagnostic tool across other SLAC user facilities. Beyond diagnostics, this approach will also help in advancing studies of ultrafast charge transport and unlocking new science in attosecond solid-state physics.

Speaker: Veronica Guo (Stanford University)

16:00 Mid-T-Baking of SRF cavities driven by RF power

Mid-T (ca. 220 to 350°C) heat treatment is known to improve the dissipation of superconducting Nb cavities by dissolving the surface oxide and diffusing oxygen into the near-surface bulk. HZB explores the use of RF power coupled into the cavity as a technique to perform the heat treatment directly in the cryostat, thereby also avoiding venting and re-oxidation following the treatment. Such an RF-driven heating may be an attractive option for in-situ processing of an operation-ready accelerator module. We have demonstrated effective RF heating both with a TESLA-9-cell and a 1.5 GHz single-cell cavity reaching temperatures of 207°C (TESLA cavity) and 260°C (VSR single cell). Whilst the TESLA-cavity was driven via the fundamental power coupler using various modes of the fundamental passband, the single cell was heated using a higher-order mode at 4.263 GHz. The later was selected because of both its strong coupling and acceptable homogeneity of RF power dissipation. Experiments took place in two cryostats, HZB’s HoBiCaT and the Large Vertical Test Stand (LVTS), operated under elevated temperatures. In this paper, details of the experimental setup and process, heating performance and, in case of the single cell, a subsequent cold test are reported.

Speaker: René Schöder (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 Migration of control system operator interfaces from EDM to Phoebus OPI at TPS

The Taiwan Photon Source (TPS) control system originally adopted the Extensible Display Manager (EDM) as its primary display framework. However, this architecture has gradually become insufficient in terms of maintainability, scalability, and system integration. To address these limitations, the TPS control system migration introduces Phoebus as the next-generation operator interface framework and redesigns the overall HMI architecture around it. Phoebus is based on a modular and layered JavaFX architecture and integrates middleware services such as alarm management, data archiving, and save-and-restore functionality. The migration process includes automated batch conversion and manual refinement, together with centralized version control to ensure deployment consistency. Using TPS as a case study, this work establishes a complete upgrade workflow and architectural solution. The introduction of Phoebus significantly improves system maintainability and scalability, while also providing a solid foundation for future modernization of the control system. This paper describes the migration process of reconstructing the TPS operator interface and related system architecture with Phoebus as the core platform.

Speaker: Chin-Kang Yang (National Synchrotron Radiation Research Center)

MOP6672_edited_version.pdf

16:00 Modelling and Experimental Studies of a X-Band Window for Mobile Linacs

Radio-frequency (RF) windows are sensitive components that ensure both RF power transmission and vacuum integrity in linear accelerators (LINACs). In the X-band frequency, improving reliability is critical for compact LINAC systems, including application in non-destructive testing and medical technologies.
This study presents an RF window designed for operation at 9.3 GHz with a 2.0 MW peak‑power design target. This window is optimised to reduce peak electric field at the ceramic–metal brazed interface while preserving low insertion loss and broad bandwidth. Coupled RF–fluidic–thermal simulations guided an extended cylindrical pillbox design exploiting the $TE_{112}$ mode.
A prototype has been fabricated, and low-power RF measurements have been carried out to validate both the design and manufacturing process. RF simulations and low-power tests show insertion losses below 0.1 dB and a standing-wave ratio lower than 1.05 at 9.3 GHz. High‑power endurance tests carried out on the prototype demonstrated stable behaviour.
Results of the engineering design will be compared with tests and discussed.

Speaker: Yoann Rozier (Epsyl, AVELION)

MOP7150_edited_version.pdf

16:00 Modelling dust grain ionisation and dynamics in flat lepton beams using a sliced approach

Interactions of dust grains with the particle beams can degrade the performance of modern high-intensity accelerators. Existing models developed for the LHC assume grains smaller than the beam size and therefore a spatially uniform primary-particle flux through the grain. This approximation breaks down in flat lepton beams, where the vertical beam size can be smaller than the dust grain.

To describe this regime, a model is introduced for the ionisation and dynamics of dust grains interacting with electron, positron, and proton beams. The grain is discretised into slices, allowing position-dependent ionisation to be treated spatially. The equation of motion is solved with a time-dependent charge using an ionisation model adapted to flat-beam geometries. Application to representative FCC-ee and SuperKEKB parameters provides first quantitative estimates of the penetration depth of charged dust grains.

Speaker: Philipp Ziegler (European Organization for Nuclear Research, Goethe University Frankfurt)

MOP1034_edited_version.pdf

16:00 Monochromatization Optics for FCC-ee Optimized Performance Study and First Attempt for IR Optics Design for FCC-ee LCC Lattice

Monochromatization is one of the most intriguing proposed operation modes of the FCC-ee, enabling a significant reduction of the centre-of-mass (CM) energy spread to a level comparable to the Higgs boson’s natural width produced through the s-mode direct channel at 125 GeV.
Previous studies demonstrated its feasibility using earlier versions of the FCC-ee Global Hybrid Correction (GHC) optics. A first draft implementation of the scheme on the Local Chromaticity Correction (LCC) lattice is explored in this paper. The performances of the new optics types are presented in terms of luminosity and energy spread, supported by the simulation results. This provides an early outlook on the potential operational flexibility of future FCC-ee configurations operating in monochromatization mode.

Speaker: Anna Korsun (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

MOP1074_edited_version.pdf

16:00 Monte Carlo studies of muon background at SND@LHC

The dominant background at the SND@LHC experiment consists of muons reaching the detector after traversing several tens of meters of rock. Monte Carlo simulations were instrumental in the experiment design and the background study. For the latter, a two-step workflow was adopted, first simulating with FLUKA proton$-$proton collisions in ATLAS and recording secondary muons on a virtual interface plane in the rock, and then propagating them to SND@LHC with Geant4. Benchmarking of simulated integral fluxes against Run-3 measurements showed a level of agreement within 10$-$30$\%$ and enabled the interpretation of the significant variations that were observed as a function of the LHC optics and beam crossing plane. In particular, the role of diffractive proton losses in an accelerator cell upstream of the detector was highlighted. On this basis, effective mitigation strategies, such as orbit bumps displacing these losses to other cells, were explored. For the HL-LHC configuration of Run-4, first estimates indicate a significantly higher muon background than in Run-3, reflecting not only the planned luminosity increase but also the larger leakage due to the magnet aperture enlargement.

Speaker: Roberto Cala' (European Organization for Nuclear Research)

MOP1030_edited_version.pdf

16:00 Morphological Evolution and Electrical Transport Studies in Ultrathin Te Films under 80 MeV Ag⁷⁺ Ion Irradiation

Ion beam irradiation is a powerful technique for defect engineering, offering precise control over ion fluence and energy. In this study, tellurium thin films deposited by thermal vapor evaporation were irradiated with 80 MeV Ag⁷⁺ ions at fluences ranging from 1×10¹¹ to 3×10¹² ions/cm². XRD shows a reduction in crystallite size and increasing tensile strain with fluence, supported by Williamson–Hall analysis.Raman spectra exhibit redshifts and broadening of the A1 and E2g modes, confirming defect formation and lattice disorder. AFM reveals fluence-dependent changes in grain morphology and surface roughness, while RBS verifies Te stoichiometry with only minor sputtering. UV–visible spectroscopy indicates enhanced optical absorption after irradiation. Hall measurements confirm n-type behavior with carrier concentration increasing from 2.12×10¹⁶ to 1.74×10¹⁷ cm⁻³. Temperature-dependent resistivity shows a reduced activation energy, and I–V curves under dark and 10 mW illumination reveal substantial photocurrent enhancement. Overall, SHI irradiation effectively tailors defect states, transport properties, and photo response in tellurium thin films for next-generation optoelectronic applications.

Speaker: Ms UPASANA BORDOLOI (Indian Institute of Technology Delhi)

16:00 Moving tons of fragile crystals with care: the CMS ECAL Enfourneur2 project

The CMS experiment at the CERN Large Hadron Collider features a high-precision electromagnetic calorimeter (ECAL) made of 61,200 lead tungstate crystals in its central (barrel) part. The crystals are both heavy and fragile, requiring extreme care during handling. As part of the HL-LHC upgrade, the ECAL barrel front-end electronics will be replaced, requiring the extraction, refurbishment, and re-insertion of all 36 supermodules (SM), each weighing about 3 tons, within a strict schedule of the technical operations inside the CMS cavern during Long Shutdown 3. A specialized machine, the Enfourneur, will be used for SM extraction. To accelerate operations, a second Enfourneur has been developed, replacing hydraulic actuators with electrical motors and controls. The new system manages three movements: rotation to the insertion angle, forward-backward motion, and controlled SM push-pull. Safety of SMs handling is ensured by numerous sensors and an advanced control system. A touchpad interface provides real-time control of SMs positioning with extreme accuracy, thanks to the implementation of electric motors and related controls, and operational safety, offering to the machine operator predefined movements, fine adjustments, and a continuous monitoring of the forces applied by the machine and ongoing deformations on the most critical metallic carpentry structures. This paper details the Enfourneur 2 design, commissioning and operational performance after an intensive testing campaign carried out at CERN.

Speaker: Roberta Bianco (Istituto Nazionale di Fisica Nucleare)

MOP7188_edited_version.pdf

16:00 Mueller, Slater & Casimir versus & Kahan & Papas: time to set the record straight

The relative fractional change of resonance frequency equals the fractional change in stored energy. This relation predicts the change of EM frequency when the walls of a metallic cavity are deformed or small objects inserted. J.M. Mueller derived this formula in 1939 by conceptual and mathematical errors. Casimir corrected those errors in 1949. The formula is also associated with J.C. Slater, published in 1946. Similar formulae were derived by Kahan in 1946 and by Papas in 1954. The Kahan version was reported, influentially, by Borgnis & Papas in the 1958 Handbook of Physics. Nevertheless, the relation is often called Slater's theorem. The Mueller, Slater and Casimir versions rely only on the properties of eigenfunctions, and electromagnetic boundary conditions at a metallic surface. The Kahan and Papas short cut to the formula relies on thermodynamics, the adiabatic theorem, perfect thermal isolation and infinite time, and that the cavity contains EM oscillations in quadrature. The latter derivation relies on assumptions that are artificial and unnecessary, and fails completely if there is no EM field present while the cavity is deformed. The situation of multiple derivations and attributions has led to some confusion. The time to set the record straight is overdue!

Speaker: Dr Shane Koscielniak (TRIUMF)

MOP7302_edited_version.pdf

16:00 Multipacting in the 150 MHz flat-top cavity of HIPA: simulation, verification, and mitigation strategies

Local X-ray production, beam losses, and surface discolouration in colloidal graphite coated regions of the cavity indicate that multipacting continues to affect the operation of the 150 MHz flat-top cavity of the HIPA Ring Cyclotron.
Particle-in-cell simulations were performed to confirm the phenomenon driving the issues and identify the specific operational conditions where it is driven. Simulations at the nominal cavity voltage show resonant electron trajectories between the electrodes and cavity wall, producing stable multipacting patterns consistent with observed surface discolouration. Guided by these results, the cavity geometry was modified to flatten the field minimum near the backplane, which demonstrated effective mitigation of multipacting undervarious operational conditions.

Speaker: Thomas Lucas (Paul Scherrer Institute)

MOP7015_edited_version.pdf

16:00 Nb3Sn on Cu SRF cavities R&D at INFN LNL

The successful development of Nb3Sn/Cu coatings for the SRF cavities of next generation particle accelerators would allow for the operation of the SRF system at 4.5 K, resulting in a reduction of the needed cryogenic power by a factor 3 with respect to what normally needed for bulk Nb cavities, operated at 2 K. In the framework of I.FAST and ISAS collaborations, an optimized recipe for Nb3Sn films deposited via DCMS has been established on small samples at INFN-LNL and is discussed in this work. Films with a Tc ≥ 17 K at deposition temperatures ≤ 650 °C on Cu substrate pre-coated with a 30-micron thick buffer layer of Nb have been successfully produced. The same deposition recipe is RF validated on QPR samples, with the results being also discussed in this work. A surface resistance < 9 nΩ at 4.5 K (at 20 mT, 417 MHz) is measured, which is about a order of magnitude larger than the baseline specifications for the LHC Nb/Cu cavities and already fulfills the requirements for the FCC-ee. Finally, the design and development of a dedicated coating system for 1.3 GHz elliptical cavities is discussed.

Speaker: Cristian Pira (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro)

MOP7030_edited_version.pdf

16:00 Neural network-based amplitude feedforward compensation algorithm for LLRF systems

In free-electron laser facilities, the amplitude-phase flatness of the Radio Frequency (RF) pulses driving the electron beam is a key factor determining beam energy spread. Imperfections in the RF driving chain, such as the static nonlinearities of the vector modulator and the high-power amplifier, can significantly increase the intra-pulse flattop amplitude error and degrade the pulse flatness. To address this, this paper proposes a U-Net deep neural network-based amplitude feedforward compensation algorithm for Low-Level Radio Frequency (LLRF) systems to suppress intra-pulse amplitude fluctuations. The algorithm has been validated at the output of a Solid-State Amplifier (SSA): under four randomly selected LLRF output configurations (amplitude, pulse width, and pulse delay), the average intra-pulse amplitude flatness (RMS) was reduced from 1.208 % to 0.398 %, and the average peak-to-peak variation was reduced from 4.683 % to 1.353 %, demonstrating a significant compensation effect

Speaker: Prof. Xiaofang Hu (University of Science and Technology of China)

MOP6697_edited_version.pdf

16:00 Neutrino fluence estimates for forward experiments at a 10 TeV muon collider

Intense and highly collimated neutrino beams are intrinsic by-products of muon decays in a high-energy muon collider. The large boost of the primary muons confines the emitted neutrinos within angular spreads of order ($10^{-5}$ rad), resulting in fluxes far exceeding those achievable in conventional neutrino facilities. Their unique properties also open opportunities for high-energy neutrino physics. In this work, the neutrino beams produced near the interaction point are characterised in terms of their spatial and energy distributions, with emphasis on their potential use for dedicated neutrino detectors. The neutrino fluence is evaluated as a function of distance from the interaction point for representative detector acceptances. At short distances, larger acceptances intercept nearly the entire neutrino core, leading to fluence saturation, while at kilometre scales different acceptances yield comparable values as beam divergence becomes significant. These results demonstrate the strong collimation and intensity of muon-collider neutrino beams and support their potential use in high-precision, high-energy neutrino studies.

Speaker: Helene Guerin (European Organization for Nuclear Research)

MOP1044_edited_version.pdf

16:00 New Warm Vacuum Interconnection Design for HL-LHC

Warm vacuum interconnections are critical components used to couple adjacent vacuum chambers in the warm sectors of the LHC. Their primary functions are to ensure vacuum tightness, to accommodate small radial misalignments between chamber flanges, and to compensate for longitudinal thermal expansion/contraction of the Long Straight Sections during bakeout operations. Within the framework of the HL-LHC project, a new generation of warm vacuum interconnections has been developed. This design introduces a novel concept of RF contacts utilising a deformable radio frequency contact bridge.

This contribution outlines the main design, manufacturing strategies and qualification of these new warm modules for the HL-LHC operation.

Speaker: Tomás Silva (European Organization for Nuclear Research)

MOP7104_edited_version.pdf

16:00 Numerical Quality Factor Statistics of an Inhomogeneously Coated SRF Cavity

Bulk niobium (Nb) is the standard material for superconducting radiofrequency (SRF) cavities, due to its high critical temperature and high critical magnetic field among pure metals. The performance of these cavities has, in recent years, approached their theoretical limits [1]. The superconductor-insulator-superconductor (SIS) multilayer approach offers
an alternative by using a thin superconducting coating, such as Nb3Sn, with higher critical magnetic field to shield the bulk superconductor from accelerating fields [2].

In our work, we model the SIS multilayer by reducing it to a surface impedance using a first-order Leontovich boundary condition, compatible with finite element methods. We then treat the coating thickness as a Gaussian random field, yielding a spatially inhomogeneous surface impedance. We present the results of a Monte-Carlo simulation
performed on a standard 9-cell 1.3 GHz TESLA cavity [3]. This simulation is used to determine statistical properties of quantities of interest, such as the quality factor, and is repeated for different correlation lengths in the Matérn kernel.

[1] A.-M. Valente-Feliciano, Superconducting RF materials other than bulk niobium: a review, Supercond. Sci. Technol. 29(11) 113002, 2016.
[2] A. Gurevich, Enhancement of rf breakdown field of superconductors by multilayer coating, Appl. Phys. Lett. 88(1) 012511, 2006.
[3] R. Wanzenberg, Monopole, dipole and quadrupole passbands of the TESLA-cell cavity, DESY, 2001.

Speaker: Aaron Gobeyn (Technical University of Darmstadt)

16:00 Numerical-experimental comparative research of titanium foil grades for accelerator output windows

The stress-strain state of titanium foils used for accelerator output windows was investigated with various foil thicknesses and titanium grades. Initial material data included deformation diagrams, densities, Young’s moduli, and Poisson’s ratios for each grade. Experimental studies were performed to validate the central displacements of Titanium Grade 2 foils. Measurements were conducted using a Hexagon precision measurement machine to determine the effective friction coefficients between titanium and two contacting materials: stainless steel 304L and oxygen-free copper. The latter was obtained via fitting the displacement curves of the initial simulations and experimental measurements conducted. These coefficients were subsequently incorporated into refined numerical simulations to obtain a more accurate representation of the stress–strain state within the sealing region of the output window assembly. Comparative analyses of the simulation results were carried out for all selected titanium grades. The advantages and limitations of each grade were evaluated in terms of mechanical performance, deformation behavior, and suitability for use in accelerator output window applications.

Speaker: Albert Hovhannisyan (Center for the Advancement of Natural Discoveries using Light Emission)

MOP7088_edited_version.pdf

16:00 Observation of intra-macropulse position monitor of $\rm H^-$ beam of CSNS Linac

The China Spallation Neutron Source (CSNS) accelerator, consisting of a $\rm H^-$ linac and a rapid cycling synchrotron (RCS), is undergoing an upgrade to increase the average beam power to 500~kW. At the CSNS linac, shorted-stripline beam position monitor~(BPM) determines beam position by averaging over the entire macro-pulse. However, significant intra-macropulse beam position fluctuations have been observed in recent commissioning, which may cause undesired beam loss and degrade the injection efficiency. In this work, an intramacropulse beam position is reconstructed method based on the signal integral algorithm. During 2025 autumn and 2026 spring operation, the intra-macropulse beam position behaviors have been uncovered at the MEBT and LRBT sections. Although beam conditions vary between two different experiments, a significant beam position drift during the first~100~{$\mu$s}, with a maximum amplitude of more than 4 mm, has been revealed.

Speaker: Weiwen Chen (Institute of High Energy Physics)

MOP6631_edited_version.pdf

16:00 Observations of 50 Hz Harmonics in the LHC Transverse Beam Spectra

In the Large Hadron Collider (LHC), several beam diagnostic systems provide turn-by-turn and bunch-by-bunch position, enabling a precise characterization of the transverse beam spectra up to high frequency. Using these instruments, the presence of external excitations at 50 Hz harmonics have been observed to affect the beam motion. In this work, we combine these measurements to study the evolution of the noise content in the LHC, with particular focus on the 50 Hz harmonics clustered around 8 kHz, which corresponds to an important range of the transverse beam spectrum.
While the exact source of the excitation remains unknown, this study provides new insights into the mechanisms behind this excitation and the evolution of the harmonic lines along the LHC cycle based on statistics collected from operational physics fills in 2025.

Speaker: Anna Radoslavova (European Organization for Nuclear Research, Goethe University Frankfurt)

MOP1003_edited_version.pdf

16:00 On-axis injection with multipole injection kicker in FCC-ee

To reach and maintain its maximum luminosity despite a beam lifetime well below 1 h, the Future Circular Lepton Collider (FCC-ee) relies on top-up injection. The present baseline scheme uses on-axis injection with a conventional one-turn orbit bump. This scheme was selected for the conceptual design study for its reliability and because it is expected to minimise background for the experiments. However, recent developments at several light sources aim at using a multipole injection kicker (MIK) as a bump-free injection alternative to minimise perturbations of the circulating beam.

This paper presents a possible implementation of a MIK for the FCC-ee collider injection scheme using pulsed sextupole or octupole magnets. The methods and results used to evaluate the injection performance against the conventional scheme are also discussed. Furthermore, a compensation scheme is proposed to minimise the effect of the MIK on the circulating beam.

Speaker: Sen Yue (European Organization for Nuclear Research)

MOP1078_edited_version.pdf

THP3001_edited_version.pdf

16:00 Online Performance Evaluation and Anomaly Detection of Beam Position Monitor System at HEPS

Beam Position Monitors (BPMs) are essential for the commissioning and stable operation of fourth-generation synchrotron light sources such as the High Energy Photon Source (HEPS). Building on the theoretical beam–electrode response of circular‑section button BPMs, we extract a set of channel‑specific coefficients from in‑situ BPM data. These coefficients remain nearly constant under varying beam positions, making them sensitive indicators of the BPM system’s health. We have developed an online performance evaluation framework that monitors these coefficients for each BPM channel, enabling the detection of gain errors and slow drifts through statistical outlier analysis and continuous trend tracking. Initial implementation in the HEPS beam measurement system has demonstrated rapid and accurate identification of abnormal BPM behavior. To further enhance diagnostic capability, machine‑learning models for anomaly detection are under active development.

Speaker: Youpeng Xie (Institute of High Energy Physics, Chinese Academy of Sciences)

16:00 Online tuning of the NSLS-II injector using Bayesian optimization with different packages

The injector of the NSLS-II consists of a linear accelerator (LINAC) that accelerates the electron beam to 170 MeV, followed by a linac-to-booster (LTB) transport line and a booster synchrotron that further increases the beam energy to 3 GeV. The performance of LINAC and LTB is critical to achieve efficient and stable beam injection. Automated online tuning is an effective method to improve injector performance. In this paper, we present an automated tuning approach based on Bayesian optimization, using different software packages to optimize the LINAC and LTB. We evaluate and compare these packages based on their ability to improve injection efficiency. Our results demonstrate that Bayesian optimization can significantly enhance injector performance and show differences in performance between different packages.

Speaker: Guimei Wang (Brookhaven National Laboratory)

MOP6307_edited_version.pdf

16:00 Operational experience on a commercial solid state power amplifier with integrated LLRF unit

In this contribution we report on the operational experience gained with a commercial off-the-shelf solid-state RF power amplifier equipped with an embedded low-level RF (LLRF) control system, in use for the sub-harmonic buncher cavity of the HB2TF project at INFN LASA. We summarize the motivations behind adopting a turnkey solution, highlighting expected benefits in terms of reliability, maintainability, and integration effort. The talk presents the main results of our testing campaign, including performance stability, response under varying operating conditions, and preliminary assessments of control accuracy. Finally, we provide notes on the synchronization strategy implemented to interface the RF control system with the laser-driven photo-cathode used as beam source.

Speaker: Michele Bertucci (Istituto Nazionale di Fisica Nucleare)

MOP7052_edited_version.pdf

16:00 Operational experience with the Cold Tuning System for ESS superconducting cavities

The European Spallation Source (ESS) is undergoing its next technical commissioning run, with the goal of achieving first Beam On Target (BOT). This milestone requires the full superconducting linac—27 cryomodules consisting of 26 Spoke, 36 Medium‑Beta, and 20 High‑Beta cavities—to achieve nominal parameters. This paper presents a statistical study of the Cold Tuning System (CTS) based on data from repeated tuning and detuning operations. The analysis focuses on tuning methodology and key parameters, assessing its repeatability and stability. The results provide a detailed characterisation of each CTS, ensuring stable cavity fields.

Speaker: Mr Artur Krawczyk (European Spallation Source)

MOP7038_edited_version.pdf

16:00 Operational loss limit in the off-momentum collimation section of the LHC

At the Large Hadron Collider (LHC) at CERN, nearly 3600 ionization chambers composing the Beam Loss Monitoring (BLM) system are distributed along the ring and at each collimator. They are responsible for protecting the machine against energy deposition originated from beam losses by requesting the beam extraction when the measured signals are above certain predetermined thresholds. The setup of these thresholds is complex and requires a combination of simulations and measurements.
In preparation for the High Luminosity-LHC (HL-LHC) era, the bunch intensity has been pushed from 1.4e11 to 1.8e11 protons during the LHC Run 3. With this higher intensity, more power is required in the radio-frequency (RF) cavities to capture the beam and reduce beam losses due to off-momentum particles, in particular at the start of the energy ramp.
The present limitation on maximum allowed beam losses on the off-momentum collimation region is around 60kW and comes from the theoretical quench limit of the matching quadrupole magnets in cell 6 (Q6) which is based on the initial LHC magnet quench models. Supported by simulations, a dedicated machine development test took place in 2025 to assess in two steps if 200kW and 500kW beam losses from off-momentum particles could be sustained in the off-momentum collimation section without quenching the Q6 or any other magnets. This paper describes the procedure of the test carried out and discusses the main findings in terms of the power loss reached and the recorded loss patterns.

Speaker: Sara Morales Vigo (European Organization for Nuclear Research)

MOP1062_edited_version.pdf

16:00 Operational Sequencer at the European Spallation Source

The Operational Sequencer is a software framework developed to automate complex and frequently executed high-level procedures that are essential to the operation of accelerator systems at the European Spallation Source (ESS). By transforming manual control room tasks into predefined sequences, the tool enhances process repeatability, reliability, and safety by reducing human error.

Designed within the ESS Integrated Control System Software group, the sequencer provides a unified architecture for defining, executing, and monitoring operational tasks. It supports multiple task execution types, scalable system design, and an intuitive graphical interface to facilitate operator oversight.

This paper presents the architectural concepts, implementation challenges, and scalability strategies of the Operational Sequencer, as well as lessons learned from its deployment during ESS commissioning. The framework represents a significant step toward efficient and reproducible operations, reducing both operator workload and time-to-beam for scientific experiments.

16:00 Optics cycles for maximum integrated luminosity in the HL-LHC

We present an update of the optics cycles foreseen during physics operation in the High-Luminosity LHC (HL-LHC) era.
New optics around the upgraded ATLAS and CMS experiments are needed due to the new quadrupole layout and lower $\beta^*$. In addition, thanks to numerous studies and lessons learnt during Run 3, the entire machine's optics will be modified to improve key aspects such as machine protection, beam-lifetime optimisation, and $\beta^*$ minimisation. This is achieved by integrating the optimisation of octupole-induced resonances, phase advances between collimators and crab cavities, new collimation optics, control of dispersion, and flat-optics options.
The contribution will present a proposal for the $\beta^*$
commissioning steps during Run 4 and Run 5 with the aim of maximising integrated luminosity. These new cycles will also be used in the Inner Triplet (IT) string operational validation programme in future collimation studies.

Speaker: Riccardo De Maria (European Organization for Nuclear Research)

MOP1061_edited_version.pdf

16:00 Optics modelling challenges for the HL-LHC

The HL-LHC will operate with very low $\beta^*$ and tight alignment constraints around the upgraded ATLAS and CMS experiments. An optimised commissioning time to reach the most pushed optics will be key to integrating significant luminosity already in the first years of operation.
The contribution presents the status and perspectives of the solutions put in place to prepare machine models that allow us to predict with the best accuracy the orbit and optics of the machine at the start of commissioning in Run 4. In particular, it shows the status of the modelling of magnetic axis deviations, the inclusion of measured magnetic transfer functions and quadrupole fringe fields in optical models, and their expected impact on the residual orbit error and optical correction convergence speed during commissioning.

Speaker: Riccardo De Maria (European Organization for Nuclear Research)

MOP1015_edited_version.pdf

16:00 Optimisation of beam transfer between RCS in the Muon Collider with synchronous phase

The Muon Collider requires fast acceleration to preserve the intensity of the decaying muons. The current design uses a chain of four rapid-cycling synchrotrons (RCS), where tens of turns are used per ring to accelerate from 63 GeV to 5000 GeV. Because of the short muon lifetime, the design uses injection and extraction while the magnets are ramping (accelerating buckets). Due to the different machine parameters and injection on accelerating buckets, there are longitudinal mismatches at transfer between the synchrotrons. By carefully controlling the synchronous phase at transfer, the mismatch can be reduced, which is essential for preserving beam quality. This contribution details the optimisation study and its predicted effect on emittance growth through the RCS chain.

Speaker: Mr Leonard Thiele (University of Rostock)

MOP1121_edited_version.pdf

16:00 Optimisation techniques for integrated luminosity with and without β* levelling for a circular collider with examples from the CERN LHC

The main performance indicator of a particle collider is the integrated luminosity. It depends not only on operational efficiency, but also on a range of beam parameters to be optimised to enhance performance. It is common to operate a collider with decaying luminosity, due to beam burn-off. However, the planned luminosity upgrade of the LHC (HL-LHC) is based on luminosity levelling: a time variation of colliding-beam offset, crossing angle and $\beta^\ast$ is used to keep luminosity constant over a certain lapse of time. The operating experience on luminosity levelling is gathered at the LHC, which uses different levelling strategies. In this work, we investigate optimisation strategies to maximise integrated luminosity without and with $\beta^\ast$ levelling. Monte Carlo simulations of years of physics runs have been performed with and without optimisation approaches. The key physical parameters are derived from a detailed analysis of the data collected at the LHC during the Run~2 and Run~3 periods. These findings provide valuable information for improving future LHC operational strategies and preparing for forthcoming collider configurations in the HL-LHC era.

Speaker: Maria Aquilina (University of Malta, European Organization for Nuclear Research)

MOP1060_edited_version.pdf

16:00 Optimization of DCCT magnetic core matching using unsupervised machine learning techniques for high-precision beam current measurement

DC Current Transformers (DCCTs) are essential instruments for non-interceptive beam current measurement in particle accelerators. The zero-flux modulation principle demands exceptional symmetry between paired magnetic cores to achieve sub-$\mu$A offset stability. Conventional core matching based on static magnetic parameters provides only an engineering approximation, as it neglects the dynamic magnetization behavior under AC modulation. This paper presents a novel approach employing unsupervised machine learning techniques applied to 6 dynamic magnetic parameters ($\mu_\mathbf{a}$, $\delta$, $B_\mathbf{r}$, $B_\mathbf{m}$, $H_\mathbf{c}$, $H_\mathbf{m}$) measured at 50 kHz sinusoidal excitation for 19 Fe-based nanocrystalline cores. Principal Component Analysis (PCA) reduces the feature space while preserving $89.64\%$ of total variance. An adaptive multi-objective K-Means strategy successfully isolates anomalous specimens ($K=2$), while a density-based evaluation framework partitions the remaining operational cores into 5 highly homogeneous sub-groups. This two-tier matching scheme enables a physically rigorous core pairing that accounts for real-world dynamic magnetization and domain wall losses under actual DCCT operating conditions.

Speaker: Weiling Huang (Institute of High Energy Physics)

16:00 Optimization of Fermilab Booster using a hybrid Bayesian and RL framework

PIP-II project will raise Fermilab Booster intensity and ramp rate. Beam losses will limit maximum power and are hard to simulate. Presently, Booster uses operator-guided empirical tuning - a challenging task due to high dimensionality, multiple objectives, critical safety constraints, and drifts. We developed a synergistic suite of Bayesian optimization (BO) and reinforcement learning (RL) tools to optimize and stabilize beam losses, including novel techniques for fast risk-aware Bayesian optimization and exploration. For initial tune-up, we performed single and multi-objective tuning using scalarized objectives comprised of critical beam loss locations, achieving significant rebalancing of losses as well as an overall improvement in transmission efficiency. To build a data-driven surrogate, active learning was used to collect data while relying on risk-aware constraints to successfully avoid beam trips. A few thousand points were collected, and a GP surrogate validated for uncertainty-aware predictions. Several off-policy RL agent architectures were trained for long term stabilization. In surrogate-based testing, SAC with BPM context and history embedding had best performance with fast and robust convergence when subjected to energy and trajectory perturbations. Experimental testing is ongoing to enable operational use.

Speaker: Nikita Kuklev (Fermi National Accelerator Laboratory)

MOP6312_edited_version.pdf

16:00 Optimized Design of a Fast Reactive Tuner for 1.3 GHz TESLA Cavities

An optimized design of a Ferroelectric Fast Reactive Tuner (FE-FRT) capable of modulating high reactive power in 1.3 GHz superconducting radiofrequency (SRF) TESLA-type cavities at the Mainz Energy-Recovering Superconducting Accelerator (MESA) on sub-microsecond time scales is presented. To mitigate microphonics-induced detuning of up to ±25 Hz in these cavities, the FE-FRT employs low-loss ferroelectric materials with sub-microsecond response times, enabling rapid frequency control without mechanical deformation while handling substantial reactive power delivered by the cavity. The proposed design effectively dissipates the heat generated in the ferroelectric wafers internally, using the exhaust radiation-shield vapor for cooling, and incorporates electrical and mechanical optimizations to improve the FE-FRT Figure of Merit. In addition, it is shown that implementing the FE-FRT in Free-Electron Laser facilities such as MESA can reduce the required peak forward RF power by about an order of magnitude. An analytical model of an FE-FRT with a 50 Hz tuning range, validated through finite-element simulations, demonstrates the feasibility and performance of this technology for SRF cavities.

Speaker: Ricardo Monroy-Villa (Johannes Gutenberg University Mainz)

16:00 Optimized low-cost, high-efficiency cavity design for 100–500 MeV proton linacs

Over the past four decades, the accelerator community has made substantial progress in advancing both normal-conducting and superconducting RF cavity design and fabrication technologies. As the global demand for new accelerator facilities continues to increase, the development of low-cost, high-efficiency RF cavities has become essential for ensuring the long-term sustainability of accelerator science.

In this work, we introduce a new RF cavity concept, designated Alansa-PL, developed by the ISIS Linac Group. This design provides a simpler and more efficient alternative to conventional coupled-cavity structures. Preliminary studies indicate that the Alansa-PL cavity exhibits enhanced performance for proton accelerators in the 100–500 MeV energy range. The conceptual design and electromagnetic modelling of the cavity, operating at 972 MHz with β = 0.5, are presented and discussed in this paper.

Speaker: Dr Jean-Baptiste Lagrange (Science and Technology Facilities Council)

MOP7019_edited_version.pdf

16:00 Optimized plasma electrolytic polishing for Cu 1.3 GHz SRF cavities

The performance of Superconducting Radio Frequency (SRF) cavities is critically dependent on surface quality. While Electropolishing (EP) has traditionally been the standard for achieving low-roughness surfaces on Niobium (Nb) and Copper (Cu) substrates, it relies on hazardous and corrosive acids. Since 2019, Legnaro National Laboratories (LNL) has developed an eco-friendly alternative: Plasma Electrolytic Polishing (PEP). Utilizing only diluted salt solutions, PEP offers significant advantages over EP, including superior removal rates ($2\text{-}8~\mu\text{m/min}$ for Nb and $3\text{-}30~\mu\text{m/min}$ for Cu) and surface roughness ($R_a$) below tens of nanometers. Furthermore, the setup has been optimized to use external cathodes, eliminating the need for complex internal cathode insertion in elliptical cavities. Following the establishment of patented recipes in 2022, PEP was successfully applied to Cu $6~\text{GHz}$ elliptical cavities, QPRs, and 3D-printed devices. A major milestone was achieved in August 2024 with the successful scaling of the process to a $1.3~\text{GHz}$ Cu elliptical cavity. In collaboration with CERN and KEK, the RF performance of PEP was validated on a hydroformed seamless cavity (coated with Nb thin film), demonstrating compatibility and slight performance improvements over standard EP. Further RF validation of PEP on differently produced Cu 1.3 GHz cavities will be presented.

Speakers: Cristian Pira (Istituto Nazionale di Fisica Nucleare), Oscar Azzolini (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro)

16:00 Oscilloscope-based TCSPC longitudinal beam diagnostics at HLS-II

Abstract: The longitudinal density distribution of electron bunch-es is a critical parameter for evaluating the performance of storage rings. To meet the requirements for real-time, cost-effective, and flexible longitudinal diagnostics for the Hefei Advanced Light Facility (HALF), we have devel-oped a Time-Correlated Single Photon Counting (TCSPC) measurement system based on a general-purpose high-speed oscilloscope at the Hefei Light Source II (HLS-II). Unlike traditional setups relying on dedicated TCSPC modules, this system utilizes an oscilloscope to directly acquire single-photon pulses from a Photomultiplier Tube (PMT). Experiments conducted at the HLS-II beamline successfully recovered the bunch fill pattern and recon-structed the photon arrival time distribution. To address the measurement errors caused by amplitude fluctuations, a post-processing algorithm incorporating Software Con-stant Fraction Discrimination (CFD) and time folding was developed. This approach effectively suppressed the time walk effect and enabled high-resolution reconstruction of the bunch profile. The results demonstrate that this oscil-loscope-based scheme possesses excellent online monitor-ing capabilities, providing a cost-effective technical solu-tion for HALF and similar facilities.

Speaker: Xing Yang (University of Science and Technology of China)

MOP6636_edited_version.pdf

16:00 Overview of superconducting undulator development at the European XFEL

This contribution describes the recent progress of the European XFEL superconducting undulators (SCUs) program. This includes: an industrially-produced NbTi-based SCU afterburner foreseen for one of the two hard X-ray lines; a prototype SCU module (S-PRESSO) in production by Bilfinger; two magnetic measurement test stands to perform quality assurance; and further development of SCU technology to reach even larger magnetic fields, by leveraging recent developments in High Temperature Superconducting (HTS) tapes for future upgrades.

Speaker: Sara Casalbuoni (European X-Ray Free-Electron Laser)

MOP7124_edited_version.pdf

16:00 Overview of the accelerator operation at China Spallation Neutron Source since its official opening

The China Spallation Neutron Source（CSNS） is the first large-scale pulsed spallation neutron source in China and the fourth of its kind in the world. It is a large multidisciplinary user facility. The facility passed national acceptance and officially opened for operation in 2018. It has been in operation for seven years. During this period, the beam power has continually increased, and both the beam runtime and availability have gradually improved. In the 2023-2024 period, it achieved a maximum beam on target time of 5,433 hours and the highest beam availability of 97.4%, which are the best among similar international facilities. This article will comprehensively introduce the operational performance of the accelerator over the past seven years, including annual beam runtime, beam availability, and statistics on hardware system downtime. Additionally, it will briefly discuss some measures taken to enhance operational reliability, including hardware upgrades, software optimizations, and maintenance strategies.

Speaker: Yuwen An (Institute of High Energy Physics, Spallation Neutron Source Science Center)

MOP6687_edited_version.pdf

16:00 Overview of the US DOE Multi-Office particle Accelerator Team (MOAT) project

: On November 24, 2025, the U.S. government launched the Genesis Mission (https://genesis.energy.gov/), a national mission to accelerate science through artificial intelligence. As part of Genesis, the US DOE Multi-Office particle Accelerator Team (MOAT) project is a bold and cross-cutting effort to leverage the power of AI at DOE’s current and future particle accelerator facilities. MOAT’s overarching goal is to fundamentally transform how particle accelerators are operated, optimized, and designed by connecting data, expertise, and innovation across the DOE complex. It will ensure DOE’s particle accelerator facilities are at the forefront of AI-enabled scientific infrastructure, and that next-generation accelerators achieve unprecedented performance, efficiency, scientific, and societal impact. We will present the project in the context of the Genesis Mission, its goals, methods and deliverables, and discuss its relationships to other projects and activities in the U.S. and abroad.

Speaker: Jean-Luc Vay (Lawrence Berkeley National Laboratory)

16:00 Parallel Beam-Based Alignment at the SIRIUS storage ring

In fourth-generation light sources such as SIRIUS, tight orbit tolerances require accurate knowledge of BPM offsets with respect to the magnetic center of nearby quadrupoles. This work presents the implementation and experimental validation, at the SIRIUS storage ring, of the Parallel Beam-Based Alignment (PBBA) method proposed by X.~Huang. This method allows the simultaneous calibration of many BPMs. Simulations and machine experiments demonstrate that the method reduces the overall BBA time from several hours to a few minutes while preserving accuracy at the level of a few micrometers, making it practical for routine accelerator operation.

Speaker: Matheus Velloso (Brazilian Synchrotron Light Laboratory, Universidade Estadual de Campinas (UNICAMP))

16:00 Particulate study of NEG pumps irradiated in the CEBAF tunnel

Non-evaporable getter (NEG) pumps are being used to maintain ultra-high vacuum in the beamline of superconducting radio-frequency (SRF) accelerators, such as the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. Because of the sensitivity of the performance of SRF cavities to particulate contamination, it is important to evaluate the integrity of the NEG material after exposure to high radiation during beam operation. The particulate from two NEG pumps based on ZAO getter alloy was measured with a particle counter in a clean-room. The pumps were assembled onto a hermetically sealed setup which was placed in the CEBAF tunnel. The setup was exposed to 24 h beam operation for ~230 days. The total gamma-rays dose measured on the test setup was ~1.6 Mrad. The total neutron dose measured at ~75 cm of the test setup was ~11 krad. The particulate count from the two pumps was measured again in the clean-room after irradiation. Whereas an increase of particulate counts was measured, compared to before irradiation, subsequent measurements indicate the absence of systematically loose particulate. The pumping speed of one of the irradiated pumps was also measured to be consistent with that of a non-irradiated one, corroborating the absence of significant damage to the ZAO NEG material due to irradiation.

Speaker: Dario Nicolosi (SAES Getters S.p.A.)

MOP7095_edited_version.pdf

16:00 Performance of the Synchrotron Radiation Collimation System in the FCC-ee Interaction Region

The electron-positron Future Circular Collider (FCC-ee) is a proposed high-luminosity lepton collider which will operate at energies ranging from 45.6 to 182.5 GeV. Each beam will radiate up to 50 MW of synchrotron radiation power, whose disposal poses obvious challenges for the machine and for the experiments. The lattice design upstream of the interaction point employs weak dipoles, within which the beam generates synchrotron radiation that could reach the detector and cause experimental background if not properly collimated. To mitigate this, a dedicated synchrotron radiation collimation system has been developed. This paper presents the performance of the FCC-ee synchrotron radiation collimation system in the interaction region in nominal conditions and during injection.

Speaker: Giulia Nigrelli (European Organization for Nuclear Research, Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Sapienza University of Rome)

16:00 Permanent magnet solenoid for a high-efficiency klystron

Since a number of years, energy efficiency has become a priority for particle accelerators both in operation and under design. Klystrons and other RF sources have been the subject of revised design in order to decrease energy consumption and increase their beam to RF efficiency. However, ancillary systems like HV systems and electromagnets can be a non-negligible power sink and may spoil the gain obtained so hard. After successfully operating a superconducting magnet as a solenoid for a high efficiency klystron since 2022, we have designed and built a permanent magnet solenoid for a similar vacuum tube that will bring the consumption of the magnetic system to zero. We will present the design, construction and final measurements of the first prototype but also illustrate the challenging path to this proof of principle and further optimization. From the design of the solenoid to the simulations of the beam inside the RF and magnetic channel, or the necessary re-design of input and output waveguides and collector. Lessons learned are as important as the results themselves towards the transfer of this technology to any other Klystron currently in the market.

Speaker: Nuria Catalan-Lasheras (European Organization for Nuclear Research)

MOP7057_edited_version.pdf

16:00 Physics-Informed Autonomous Fault Diagnosis Agent for SSRF Using Large Language Models

To advance autonomous operation at the Shanghai Synchrotron Radiation Facility (SSRF), we developed a diagnostic agent using a locally deployed Qwen3-30B model. Unlike black-box predictors, this agent employs physics-informed context engineering by langgraph to emulate expert reasoning: it iteratively excludes healthy subsystems, identifies parameter drifts, and validates hypotheses by referencing historical fault records. The system is designed to handle general accelerator anomalies, ranging from transient trips to long-term drifts, providing a secure, intelligent, and modular framework that facilitates continuous upgrades. Currently, a lightweight supervisory layer continuously monitors beam status and triggers the agent only upon anomaly detection, ensuring efficient, on-demand diagnosis.

Speaker: Yihao Gong (Shanghai Synchrotron Radiation Facility)

16:00 Post-processing of additively manufactured pure copper RFQ elements

The utmost design freedom of additive manufacturing can be leveraged to fabricate complex particle accelerator components, such as the radiofrequency quadrupole (RFQ). However, the high surface roughness typical of as-printed parts represents a major barrier to the integration of additive manufacturing technologies into established fabrication workflows. This work investigates finishing processes aimed at improving the surface quality of additively manufactured RFQ components, with a focus on the hard-to-access vane tip region. A dedicated mock-up was developed, consisting of a copper vane representing a one-quarter RFQ section, mounted in a plastic holder to replicate the full part. This setup allows the copper part to be removed after each treatment step to measure material removal and assess effects on vane modulation, surface roughness, and overall geometric accuracy. Both mechanical mass finishing with abrasive media and chemical polishing were examined, applying each treatment in multiple intermediate steps. Comprehensive surface characterization was conducted after each finishing stage by means of profilometry, 2D and 3D roughness measurements, and 3D scanning to determine correlations between process parameters and resulting surface quality. The objective is to develop an optimed finishing strategy capable of achieving the surface quality and geometric accuracy required by RFQ and other advanced particle accelerator components.

Speaker: Tobia Romano (Politecnico di Milano, Riga Technical University)

MOP7172_edited_version.pdf

16:00 Power couplers conditioning and multipacting simulations for the ESS- Bilbao ARGITU RFQ

The ARGITU RFQ at ESS-Bilbao is a 352.2 MHz, 4-vane RFQ that will
accelerate protons from 45 keV to 3.0 MeV. The RF power comes from a
modulator/klystron by rectangular waveguides that end in coaxial lines
that are finished by the two loop power couplers. The couplers are made
of copper and no brazing has been used in their production. For this
reason, the vacuum/air window is made of PEEK material attached by
mechanical pressure to the copper structure. For the initial stages of
the ARGITU RFQ, the duty cycle will not rise above 1%, so these
couplers were designed with no active cooling. This paper summarizes the conditioning setup and focuses on the RF, thermal and multipacting simulations used to define safe high-power conditioning limits.

Speakers: Ibon Bustinduy (ESS Bilbao), Juan Luis Muñoz (ESS Bilbao)

MOP7012_edited_version.pdf

16:00 Powering Concepts for Resistive Magnets in the Muon Collider Rapid Cycling Synchrotron

The development of a power converter for the resistive magnets of the Muon Collider Rapid Cycling Synchrotron (RCS) represents one of the most critical challenges of the muon accelerator system, given the required peak power levels in the 50–100 GW range. To address this, a modular resonant converter is proposed, consisting of several hundred identical series-connected cells interleaved with the magnets. This configuration distributes the total system voltage — on the order of tens of megavolts — evenly across the cells, while limiting the insulation voltage to ground. A key design requirement is a highly repeatable current ramp across successive pulses, with deviations at or below 100 ppm. Given the very short acceleration times, a pulse-to-pulse Iterative Learning Control (ILC) strategy is proposed to progressively meet this target. The paper presents the main converter topologies, repeatability studies, simulation results, and the proposed control approaches.

Speaker: Fulvio Boattini (European Organization for Nuclear Research)

MOP1099_edited_version.pdf

16:00 Preliminary Design and Performance Verification of a High-Power, Wide Dynamic Range BPM Analog Front-End for the CSNS-II RCS

The power upgrade of the China Spallation Neutron Source Phase II (CSNS-II) requires the Rapid Cycling Synchrotron (RCS) BPM system to operate under an extreme 107 dB ultra-wide dynamic range (20 mV to 50 V) and high signal power. The primary design challenges are mitigating thermal drift, suppressing reflections from impedance mismatch, and enhancing low-energy SNR.This paper presents the preliminary design and performance validation of an analog front-end board, adapting successful solutions from facilities like J-PARC MR. The design integrates thin-film resistor attenuators with an impedance tuning network for improved stability and reflection control. Crucially, a hybrid fast/slow switching attenuation strategy is applied: millisecond-level slow switching handles macroscopic changes, while innovative nanosecond-level fast switching enables dynamic gain conditioning during acceleration, significantly boosting the system's SNR.Performance verification results (including attenuation and S21 characteristics) confirm the feasibility and core metrics of the circuit under high-power conditions, providing essential technical guidance for the final implementation at the CSNS-II RCS.

Speaker: Renjun Yang (Institute of High Energy Physics)

MOP6625_edited_version.pdf

16:00 Preliminary Design of Beam Feedback Systems for the Shenzhen Superconducting Soft X-ray Free Electron Laser

The Shenzhen Superconducting Soft X-ray Free Electron Laser (S3FEL) requires a high-quality electron beam with stable energy, bunch length, and arrival time to ensure efficient lasing. To maintain stringent beam quality, a comprehensive beam feedback system has been preliminarily designed, incorporating five dedicated feedback loops:
1.Gun Feedback: Monitors bunch charge and arrival time after the electron gun, controlling the input laser power and delay to stabilize charge and timing.
2.Laser Heater Feedback: Measures beam energy at the laser heater and adjusts the RF amplitude of small module CM00 and large module CM01 accordingly.
3.Bunch Compressor 1 (BC1) Feedback: Monitors beam energy, energy spread, and bunch length in BC1, regulating RF amplitude and phase of large modules CM02, CM03 and harmonic cavities CMH01, CMH02.
4.Bunch Compressor 2 (BC2) Feedback: Similarly monitors beam parameters in BC2 and controls RF amplitude and phase of large modules CM04–CM09.
5.Linac End Feedback: Measures final beam energy and adjusts RF amplitude and phase of large modules CM10–CM20 to ensure energy stability before transport to the undulator.
This integrated feedback design aims to suppress slow drifts, enhance beam stability, and provide the reliable beam quality required for high-performance soft X-ray FEL operation at S3FEL.

Speaker: Zhiyuan Zhang (Institute of Advanced Light Source Facilities, Shenzhen)

MOP6677_edited_version.pdf

16:00 Preliminary power balance assessment of the PERLE Energy Recovery Linac

The PERLE project aims to build a high power electron Energy Recovery Linac (ERL) demonstrator (5 MW) to develop and apply the energy recovery technique in a multi turn configuration. In an initial intermediate phase PERLE will operate in a single turn mode with a 5 mA beam at 89 MeV. In its final layout the machine will run in a three turn mode, delivering a 20 mA electron beam at 250 MeV. These challenging parameters make PERLE a unique multi turn ERL facility operating in an unexplored power regime, enabling the study and validation of a broad range of accelerator phenomena and paving the way for future, larger scale ERLs.
The principal advantage of ERLs lies in their ability to return the power of a spent beam to the RF system. This recovered power can then be used for acceleration with practically no losses, thereby markedly improving the sustainability of high power machines. One of PERLE’s goals is to assess the overall sustainability of a multi megawatt ERL. In this work we present the current status of the studies carried out to evaluate the total electrical power consumption (“plug to grid”) of the accelerator for various operating modes—both single turn and multi turn—and relate this consumption to the average beam power delivered at the interaction point. We also discuss the power balance of a high power multi turn ERL and compare its efficiency with that of conventional accelerator types; e.g., linacs.

Speaker: Dr Frédéric Bouly (Laboratoire de Physique Subatomique et de Cosmologie)

MOP7179_edited_version.pdf

16:00 Preliminary study of a bunch-by-bunch monitoring system for the TPS booster synchrotron

The Taiwan Photon Source (TPS) booster synchrotron has been in routine operation since 2015, accelerating electron beams from 150 MeV to 3 GeV at a 3 Hz repetition rate. Ensuring beam stability during the energy ramp is essential, particularly through tune correction to mitigate particle loss associated with betatron resonances. Tune variations primarily arise from magnetic field imperfections, space-charge effects, and injection-related errors. Effective tune control is therefore required to maintain the beam on its intended trajectory and to achieve high acceleration efficiency. To support this objective, a bunch-by-bunch feedback processor has been adapted as a diagnostic toolkit capable of measuring and tracking the booster tune throughout the energy ramp, enabling real-time correction. The system acquires waveform data using configurable multi-bunch or single-bunch triggers, and advanced signal-processing techniques are applied to suppress background noise for improved spectral clarity. Ultimately, the developed system aims to perform tune compensation to reduce tune fluctuations and enhance injection efficiency. This report summarizes the development and performance evaluation of the proposed efforts.

Speaker: Jui-Che Huang (National Synchrotron Radiation Research Center)

MOP6663_edited_version.pdf

16:00 Preparations for the execution phase of BDF/SHiP at the HI-ECN3 facility in CERN's North Area

The High-Intensity ECN3 (HI-ECN3) Project will upgrade the ECN3 underground experimental area in CERN’s North Area, to host the Beam Dump Facility (BDF) and the SHiP experiment. The required refurbishment of underground infrastructure and associated surface facilities is scheduled for Long Shutdown 3 (LS3), while installation of BDF and SHiP is foreseen in 2030 and beam commissioning of the BDF is planned in 2031. HI-ECN3 must share specialised resources during LS3 with other activities in the SPS and the North Area, without having priority over them. This makes the coordination and scheduling of limited resources a challenge, particularly during LS3 when the workload will be at its maximum. To reduce these risks, a set of preparatory measures have been implemented ahead of LS3. This contribution details the key preparatory activities and efforts to smooth the demand on resources during LS3 and enhance the readiness of the ECN3 facility for the subsequent installation phase.

Speaker: Ixone Angulo Vaquero (European Organization for Nuclear Research)

MOP1119_edited_version.pdf

16:00 Principle and First Beam Test of Bunch Length Measurement via Rydberg Atom-Based Wireless Sensing at SXFEL

Accurate measurement of electron bunch length is critical for the performance optimization of X-ray free-electron lasers (FELs). Conventional techniques face challenges in achieving simultaneous single-shot, non-destructive, and femtosecond-level resolution. This paper presents a novel diagnostic method based on quantum wireless sensing using Rydberg atoms. The principle utilizes the extreme sensitivity of Rydberg atoms to terahertz (THz) electric fields to detect coherent Synchrotron Radiation (CSR) from electron bunches in a magnetic chicane. Theoretical calculations modeling the CSR generation in the chicane of an FEL beamline and its interaction with a Rydberg atomic system are detailed. Furthermore, we report on the development and installation of a proof-of-principle beam test platform at the BC2 chicane of the Shanghai Soft X-ray FEL (SXFEL). The platform integrates a vacuum CSR extraction port, THz beam optics, and a portable Rydberg atom sensor. Preliminary results from beam experiments are also discussed.

Speaker: Jian Chen (Shanghai Synchrotron Radiation Facility)

16:00 Probing the ultimate beta* reach of the LHC

In 2026, the Large Hadron Collider will conclude its final operational run, before being upgraded to the High-Luminosity Large Hadron Collider during the following long-shutdown. Originally conceived with a nominal beta of 0.55m in both planes, over successive years, its optics design has been steadily pushed beyond those initial goals, with round optics down to 0.25m/0.25m (2018), and flat optics down to 0.6m/0.18m (2025) used in operation. In 2025, dedicated beam-studies were performed to test the viability of controlling beta waist errors at such low-beta, and to explore the viability of squeezing and commissioning the optics even further. Possible operational scenarios for 0.5m/0.15m and 0.4m/0.12m were tested, and optics measurements down to a potential minimum beta of 0.07m achieved. The outcome of these tests will be presented.

Speaker: Mattia Stefanelli (European Organization for Nuclear Research)

MOP1066_edited_version.pdf

16:00 Production of the HL-LHC experimental beam vacuum chambers

For the High-Luminosity LHC (HL-LHC) era following the third long shutdown (LS3), new generations of experimental vacuum chambers will be installed in the ATLAS, ALICE, CMS, and LHCb experiments. These chambers, located at the interaction points, ensure the required beam vacuum conditions while minimizing the impact of chamber materials on detector performance. The HL-LHC upgrade imposes tighter demands on mechanical precision, radiation tolerance, and surface quality to sustain higher luminosity and dose levels. Building on the experience gained during LS2, the LS3 designs introduce optimized materials, geometry, and production methods to meet these challenges.

This contribution outlines the main design principles, manufacturing strategies, and qualification steps guiding the development of the LS3 experimental vacuum chambers for HL-LHC operation.

Speaker: Josef Sestak (European Organization for Nuclear Research)

MOP7110_edited_version.pdf

16:00 Progress in Advanced Ferroelectric Technologies for Fast SRF Cavity Tuning

Fast tuning of SRF cavities at high power is critically important for applications like correction of microphonics, transient beam loading and fast frequency switching. With the talk, we present recent developments of the active elements for the high-power Ferroelectric Fast Reactive Tuners (FRT). This technique has now become practically feasible due to the recent development of a new extremely low loss and fast (10 ns-100 ns time range) ferroelectric material, which has been evaluated, and fast frequency tuning has been demonstrated. The first FRT was developed by Euclid in collaboration with FNAL and BNL and successfully tested at low power for the microphonic compensation at CERN. The Horizon Europe iSAS project focuses on improving accelerator efficiency and includes the integration of a ferroelectric fast reactive tuner (FE-FRT) for high power applications to enhance energy conservation. In the U.S., FE-FRT technology is under active development for microphonics compensation in CEBAF as well. With this talk, we will overview the current FRT designs that are been developed for high power SRF systems and discuss the active ferroelectric elements parameters of the FRT for the microphonics and transient beam loading compensations**.

Speaker: Chunguang Jing (Euclid Techlabs (United States))

16:00 Progress in the development of the community Particle Accelerator Language Standard (PALS)

The Particle Accelerator Language Standard (PALS) is a community effort to create an open standard to promote lattice information exchange for particle accelerators. PALS development is a community-wide international effort involving accelerator physicists from multiple institutions. While it started as a lattice standard for beam dynamics simulations, it is now being extended to support other particle accelerator activities, in particular accelerator operation.

With new accelerators that are becoming more complex, larger collaborations and the increasing imprint of artificial intelligence in all accelerator activities (from design to operation to workforce development), the imperative for a common, standardized accelerator ontology has been transitioning from “nice-to-have” to “must-have”.

We will present the status of the project, its relations to other projects, including to two of the particle accelerator projects of the newly announced US DOE Genesis Mission: the Multi-Office Accelerator Team (MOAT) project and the Nuclear physics AI-Ready Accelerator Data (NARAD) project.

Speaker: David Sagan (Cornell University (CLASSE))

MOP6394_edited_version.pdf

16:00 Progress of developing the bunch-by-bunch feedback system for the CSNS RCS

The Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS) is planned to upgrade its beam power from the current 100 kW to 500 kW in the CSNS-II phase. However, significant beam-intensity-dependent transverse instability has already been observed during routine 100 kW operation. As the beam power increases further, this instability is expected to become much stronger. To effectively suppress the coherent transverse oscillations induced by impedance wakefields and injection errors, a bunch-by-bunch transverse feedback system is essential. This paper evaluates the performance of the digital filter and the complete bunch-by-bunch feedback chain, from the front-end electronics through the power amplifier to the strip-line kicker. Feedback system simulations are performed to optimize key parameters, providing critical guidance for the design, commissioning, and future operation of the system.

Speaker: Weiwen Chen (Institute of High Energy Physics, Chinese Academy of Sciences)

MOP6632_edited_version.pdf

16:00 Progress on low-level RF qualification of a 3d-printed 704.4 MHz CH cavity

Additive manufacturing enables compact accelerating
structures with complex internal features such as inte-grated cooling channels. Within the Resonators Additively Constructed for Experiments project at GSI, a 3D-printed 704.4 MHz CH cavity was developed as a compact high-frequency H-mode prototype. This paper reports on the progress from the first low-level radio-frequency (RF) char-acterization to the modified, copper-plated and retuned cav-ity configuration. Initial measurements showed a resonance frequency below the target value and an asymmetric field distribution, attributed to the initial cavity geometry, prelimi-nary contact conditions and the capacitive coupling scheme.
Based on these findings, the cavity configuration was re-fined by replacing the capacitive coupling with an inductive loop and adding four static tuners. After these modifica-tions, the field asymmetry was reduced and the cavity fre-quency could be adjusted to the design value of 704.4 MHz. The dynamic tuners provided a measured tuning range from 701.9 MHz to 706.3 MHz. Together with the quality-factor evaluation and computed-tomography inspection of the inte-grated cooling channels, these results confirm the successful low-level RF and manufacturing qualification toward future high-power operation.

Speaker: Ramy Cherif (GSI Helmholtz Centre for Heavy Ion Research)

MOP7003_edited_version.pdf

16:00 Progress on optics measurements for the FCC-ee

Precise optics measurements will be crucial for commissioning and optimising the Future Circular electron-positron Collider, FCC-ee, across its full energy range. To prepare for this challenge, simulation studies have been performed to evaluate the accuracy and robustness of Turn-by-Turn (TbT) based optics diagnostics applied to the FCC-ee. A central element of this effort is the use of an AC-dipole to generate coherent, controlled beam oscillations suitable for high-quality TbT data analysis.
This contribution presents the latest progress in simulated TbT optics measurements, including sensitivity to Beam Position Monitor (BPM) noise. Particular emphasis is placed on exploring the first specifications for BPMs and AC-dipoles for the FCC-ee, accounting for constraints related to synchrotron-radiation damping, excitation strength, and driving frequency. The results provide essential input for defining the optics-measurement strategy, hardware requirements, and correction schemes foreseen for the FCC-ee.

Speaker: Jacqueline Keintzel (European Organization for Nuclear Research)

MOP1038_edited_version.pdf

16:00 Proof-of-principle experimental design of solenoid-based relativistic electron beam pulse compression

Relativistic electron beam pulse compression can enhance the beam current intensity within the pulse and generate higher peak current, showing significant potential for applications such as FLASH radiotherapy and wakefield acceleration. This paper proposes a proof-of-principle experimental design for a solenoid-based electron beam pulse compression scheme. The core device of the experiment, namely the magnetic compressor, has an approximately cylindrical structure with a diameter of 42 cm and a height of 47 cm. By utilizing the uniform magnetic field generated by the solenoids, the compressor converts the energy difference of the injected beam bunch into a path-length difference to achieve pulse compression. Simulation studies show that, under a transverse geometric emittance of $10~\mathrm{mm\cdot mrad}$, the beam loss remains below 10%, while the output current waveform exhibits a peak-to-peak ratio of approximately 5, demonstrating an obvious pulse compression effect.

Speaker: Weihong Huang (Tsinghua University)

MOP8604_edited_version.pdf

16:00 Proposed collimation layout for the FCC-ee with local chromaticity correction optics

The Future Circular electron–positron Collider (FCC-ee), with a circumference of approximately 90 km, is designed to push both the luminosity and energy frontiers for high-brightness lepton beams. The unprecedented stored beam energy, reaching up to 17.7 MJ -- around two orders of magnitude greater than in any previous lepton collider -- poses major challenges for safe operation. Uncontrolled losses could result in high experimental backgrounds, downtime, or even damage to accelerator components, making an efficient and reliable collimation system essential.

Two layouts and optics configurations are currently under consideration for the FCC-ee: the Global Hybrid Correction (GHC) and the Local Chromaticity Correction (LCC) schemes. While a collimation concept has previously been proposed for the GHC optics, this paper presents a new collimation layout specifically designed for the LCC lattice. The collimation performance is then compared between the two optics and layout versions under representative loss scenarios to identify in which optics the collimation system works best.

Speaker: Giovanni Iadarola (European Organization for Nuclear Research)

MOP1052_edited_version.pdf

16:00 Prototype development of a compact HTS wiggler for Synchrotron Light Sources

The European Synchrotron Radiation Facility (ESRF) is developing a compact high-temperature superconducting (HTS) wiggler for beamline BM18, consisting of three pole pairs delivering up to 1.58 T, with variable field capability within a minimal footprint. ReBCO HTS tapes enable high current densities and allow current-controlled field scans, eliminating bulky mechanical phase shifters.

The magnet comprises racetrack coils and an iron yoke optimized with COMSOL and RADIA to satisfy field specifications at 65 K. A no-insulation winding technique enhances robustness against quenches. Numerical optimization minimizes the first and second field integrals over the operating current range.

Prototype development is advancing: winding tests at 77 K have started, providing initial measurements of magnetic field intensity and homogeneity, inter-turn resistance, and mechanical response of the winding. These results provide crucial information for the completion of the remaining coils, upcoming cold tests, and the validation of the design for synchrotron operations.

Speaker: Lorenzo Bortot (European Synchrotron Radiation Facility)

MOP7071_edited_version.pdf

16:00 Prototyping of a tunable permanent magnet quadrupole

Within the Research Facility 2.0 (RF2.0)* project, one of the objectives is the development of novel permanent-magnet technologies and refurbishment strategies aimed at reducing energy consumption in accelerator facilities. In this context, ALBA, ELYTT, and HZB are jointly developing a tunable quadrupole prototype based on permanent magnets, conceived as a demonstrator for next-generation, energy-efficient magnet systems.
The prototype is designed to achieve high-gradient focusing while drastically reducing power consumption relative to conventional electromagnets, eliminating the need for large coils and water cooling. Its compact architecture also eases integration into densely packed storage-ring lattices. Tunability is provided through a hybrid approach combining movable soft-iron elements and small auxiliary coils, offering a wide operational range with minimal energy demand.
This contribution presents the electromagnetic and mechanical design of the prototype, the assembly strategy, and the current status of the manufacturing and testing.

Speakers: Jens Voelker (Helmholtz-Zentrum Berlin für Materialien und Energie), Jordi Marcos (ALBA Synchrotron (Spain))

MOP7066_edited_version.pdf

16:00 Pulse stretcher for the PADME-X17 experiment

The PADME-X17 experiment is searching for a light dark matter candidate. The experiment would greatly benefit from the availability of a dedicated beam with long pulse duration and minimal instantaneous current. In this contribution, a third-order resonant slow-extraction scheme is considered, starting from the present lattice of the DAFNE damping ring. This solution, already integrated with the DAFNE complex, could provide the necessary positron-beam improvements within the existing facility.
This study, currently aimed at improving the sensitivity of fixed-target experiments with positrons, could open new possibilities for beamlines based on the beam extracted from the damping ring.

Speaker: Antonio De Santis (Istituto Nazionale di Fisica Nucleare)

MOP1089_edited_version.pdf

16:00 Python-EPICS RF Conditioning Automatic Control System at the Spallation Neutron Source

The RF Test Facility (RFTF) at the Spallation Neutron Source (SNS) is used for RF conditioning of components such as ceramic windows and couplers prior to their installation in charged-particle accelerators. This process involves exposing components to high-power RF fields and thermal cycling to improve performance and remove impurities. To automate and optimize this process, a Python-based EPICS control system was developed, along with hardware upgrades. The system enables real-time monitoring and control of RF power levels, temperature, and vacuum pressure. A user-friendly graphical interface was implemented using CS-Studio (Phoebus), allowing operators to adjust parameters and collect data efficiently. The system integrates the High Power Protection Module (HPM) for interlocks based on vacuum and arc detection, ensuring safe operation. These upgrades have significantly improved the efficiency, accuracy, and safety of RF conditioning at the SNS RFTF. This presentation introduces the updated RF conditioning system, highlighting the software and hardware developments, and its application in support of the Proton Power Upgrade (PPU) project at SNS.

Speaker: Sung-Woo Lee (Oak Ridge National Laboratory)

MOP6388_edited_version.pdf

16:00 Qualification and commissioning of superconducting magnets for the S3 spectrometer at GANIL

In order to achieve optimal performance in terms of transmission and separation for the S3 spectrometer, the project team decided to design superconducting magnets integrating 11 magnetic functions in a single cryostat. There are seven of these magnets, called Superconducting Multipole Triplets, in the spectrometer, and they operate at liquid helium temperature. These are unique objects with no equivalent anywhere else in the world, offering a very high degree of integration. This complexity has resulted in a significant commissioning delay and the need for a dedicated team to operate this set of magnets. This presentation will show the progress made in qualifying the various functions associated with these magnets: the qualification of cryogenic, electrical, and magnetic functions.

Speaker: Marc-Hervé Stodel (Grand Accélérateur National d'Ions Lourds)

MOV7001_edited_version.pdf

16:00 Quality assurance for the HL-LHC beam screen production

The HL-LHC project is currently in the fabrication and assembly phase for numerous components and systems, in particular the new beam-screen assemblies to be installed inside the upgraded final-focusing superconducting magnets operating at 1.9 K. These complex beam screens integrate tungsten absorbers and exist in two variants: the Q1 and Q2 types, with absorber thicknesses of 16 mm and 6 mm, respectively. In total, 24 assemblies will be installed. Their successful implementation requires complex design work, non-standard and demanding manufacturing processes, and stringent quality assurance. Fabrication has proven to be very challenging in terms of welding and assembly and requires close follow-up and dedicated qualification processes throughout the manufacturing phase.
To maintain a high standard of manufacturing, a Quality Management approach derived from industrial standards and based on ISO 9001 principles, has been implemented. This paper presents how the quality-management framework is deployed throughout the project phases and how it ensures traceability, smooth process execution, and compliance with the required workflows and technical specifications.

Speaker: Dominika Sadowska (European Organization for Nuclear Research)

MOP7109_edited_version.pdf

16:00 R&D activities in view of PIP-II LB650 cavity production

A joint LASA–Fermilab activity is in progress to study the impact of key surface processing steps on the performance of LB650 superconducting cavities in view of future series production. Among the several cavity preparation steps, electropolishing (EP) and mid-temperature heat treatment are considered the most critical and require specific optimization for the LB650 geometry. Single-cell and 5-cell cavities are used as test prototypes to investigate the effects of EP and mid-temperature bake at 350 °C. Vertical RF tests are performed at Fermilab after EP and after the mid-T bake under identical conditions. The ongoing program aims to provide insight into the evolution of Q₀ and accelerating gradient along the processing sequence. Preliminary observations and results are here presented.

Speaker: Michele Bertucci (Istituto Nazionale di Fisica Nucleare, Laboratori Acceleratori e Superconduttività Applicata)

16:00 R&D of the Bunch-by-Bunch Feedback Processor Prototype for HALF

The Hefei Advanced Light Facility (HALF) is designed to generate and operate with a beam current of up to 350 mA while maintaining the beam emittance at the diffraction-limited level. The bunch-by-bunch feedback system serves as a critical tool for suppressing beam instabilities, requiring feedback control targeting the position oscillations of each bunch. To meet this demand, the engineering team has independently developed a bunch-by-bunch feedback system, fabricated a prototype, and conducted relevant tests. Through high-precision phase alignment, the analog front-end conditions the original signals into high-precision and wide-dynamic-range sum-and-difference signals. Utilizing the phase-splitting and time-delaying method, the processor can measure the high-precision three-dimensional (3D) position of each bunch and implement feedback control accordingly. This paper presents the design of the system as well as the details of the prototype development and testing.

Speaker: Xing Yang (University of Science and Technology of China)

MOP6682_edited_version.pdf

16:00 R&D small focal spot Linacs for industrial and cargo scanning at Elekom

Electron linear accelerators(linacs) have been widely used in industrial Non-Destructive Testing (NDT) and cargo scanning for decades, exploiting their X-ray radiography features. The focal spot size is a critical parameter of an X-ray source, where a smaller focal spot size generally yields higher image resolution. To enhance system image resolution, Chengdu Elekom Vaccum Electron Technology Co. Ltd has developed a series of small focal spot linacs for industrial and cargo scanning applications. These linacs feature focal spot size bellow 1 mm, with some type achieving sub-0.5 mm performance. After rigorous testing in laboratory and field environments, they have demonstrated high dose rates and extended operational lifetimes. This paper will provide a detailed analysis of these linacs' performance.

Speaker: Yongtao Liu (Xihua University)

MOP8606_edited_version.pdf

16:00 Radiation and power deposition studies for the FCC-ee halo collimation system

The betatron and momentum collimation system of the the Future Circular Collider (FCC-ee) is essential to isolate losses away from the experiments and other machine elements, thus reducing the radiation background in the experiments, and avoiding damage to the machine in case of accidental beam losses. The primary and secondary collimators of the collimation hierarchy, employed to scatter halo particles from the beam and remove them, respectively, will be accommodated in one of the technical insertions of the collider ring (Point F). In this paper, FLUKA simulations are presented for the collimation straight section, addressing both normal operation and accidental scenarios. The power deposition is determined for all elements in the section following beam impacts on the collimator jaws, including other collimators as well as dipole and quadrupole magnets. In particular, the fraction of the stored beam which can be safely absorbed by the collimators is estimated. Finally, the paper discusses the radiation levels in the Point F tunnel resulting from beam losses on the collimation system, and the resulting radiation hardness requirements for machine equipment and infrastructure.

Speaker: Kate Taylor (European Organization for Nuclear Research)

MOP1035_edited_version.pdf

16:00 Radiation environment in the FCC-ee arcs caused by synchrotron photon emission

In a high-energy lepton collider such as the Future Circular Collider (FCC-ee) at CERN, several phenomena create a challenging radiation environment for accelerator components and equipment including cables and electronics. This paper examines synchrotron radiation (SR), dominating at the highest beam energies (ttbar) for two different optics schemes.

Recent developments in the design of photon stoppers and dedicated radiation shielding are presented, highlighting progress towards a more realistic configuration while maintaining acceptable annual ionizing dose levels. The study covers the contribution of the collider ring and the impact on the attached alcoves, housing radiation sensitive equipment. The absorbed power in accelerator components and the surrounding tunnel environment is evaluated for various operation modes to ensure compliance with the thermal load limits of the ventilation system. Furthermore, radiation and particle fluence levels dominated by photo-neutron production are quantified for the electronics bunkers located below the beamline. These results are used to assess the feasibility of employing radiation-tolerant, commercial-off-the-shelf electronics in these areas.

Speaker: Kate Taylor (European Organization for Nuclear Research)

MOP1014_edited_version.pdf

16:00 RCS polarization correction using information theoretic and machine learning tools

One of the greatest challenges for the EIC’s proposed Rapid Cycling Synchrotron will be to achieve high polarization transmission to 18 GeV. While SVD based orbit smoothing should be sufficient to achieve over 99% polarization transmission up to 10 GeV, the growth in the strength of residual imperfection spin resonances make achieving polarization transmission of 90% and above to 18 GeV more difficult when base vertical quadrupole misalignments grow larger than 100 microns. One promising approach is to deploy estimates of the vertical quadrupole misalignments using simple misalignment to BPM response matrices. Using this, the stronger imperfection spin resonances from 10 to 18 GeV can be estimated and corrected using vertical correctors. With this approach, base quadrupole misalignments of up to 200 microns can now be tolerated. However, the existence of dipole rolls limits the effectiveness of this approach since their effect on the orbit as registered at the BPMs is very similar. Here we describe a new approach which leverages machine learning methods to guide perturbations to the lattice that maximize the net Fisher’s Information and thus help increase the accuracy of imperfection spin resonance corrections.

Speaker: Vincent Schoefer (Brookhaven National Laboratory)

MOP1301_edited_version.pdf

16:00 Real time longitudinal beam measurements in the Crocker Nuclear Laboratory isochronous cyclotron

The UC Davis Crocker Nuclear Laboratory (CNL) operates a 76-inch isochronous cyclotron dating to the 1960s, with limited internal beam diagnostic instrumentation. Direct measurements of the Cyclotron beam are challenging due to the harsh environment, including high radiation, strong magnetic fields, RF interference, and spatial constraints. A novel beam probe has been developed for longitudinal bunch structure and phase measurements in a 15 mm square transverse profile with 16 independent pixels. The probe consists of a segmented fast plastic scintillator array coupled via fiber optics to external Silicon Photomultipliers (SiPMs), mounted on a radially translating probe. Bunch length and phase information are measured and analyzed in real time, with continuously updating visualizations available to operators and to downstream real-time analysis tools. Additionally, the collected data are archived for offline analysis, supporting the development of simulations for the CNL Cyclotron. The Fast Beam Probe opens the door to improved beam stability, more accurate modeling, and future integration with automated control systems at CNL.

Speaker: Logan Knudson (University of California, Davis)

MOP6371_edited_version.pdf

16:00 Real-time autonomous 6D phase-space tomography for LCLS-II injector monitoring

Characterizing the full 6-dimensional phase-space distribution of beams from the LCLS-II photoinjector is essential for understanding and optimizing downstream accelerator performance. Long-term monitoring of this distribution is equally important for detecting drifts in machine state and implementing timely corrective actions. Continuous 6D characterization during routine operation demands reliable tomographic diagnostic measurements and fast, efficient reconstruction methods. In this work, we demonstrate the first fully autonomous 6D beam-tomography system deployed on a parasitic diagnostic line at LCLS-II. Using machine learning-based control algorithms, the system autonomously configures and executes tomographic manipulations within operational constraints, adaptively re-optimizing beamline parameters and scan ranges in response to changes in the incoming beam. Measurements are streamed to the S3DF computing cluster, where we perform online, 6-dimensional phase-space reconstruction using generative techniques. This framework produces detailed 6-dimensional beam reconstructions at a rate of once every five minutes, enabling multi-hour tracking of injector beam evolution with unprecedented fidelity. These results represent a significant step toward routine, real-time 6-dimensional beam diagnostics for current and next-generation accelerator facilities.

Speaker: Auralee Edelen (SLAC National Accelerator Laboratory)

16:00 Real-time tomography of synchrotron longitudinal phase space based on spatio-temporal neural networks

Accurate acquisition of the longitudinal phase space distribution is crucial for synchrotron optimization, but traditional tomography requires minutes per reconstruction, preventing real-time diagnostics. To resolve this, we propose a novel spatio-temporal neural network integrating 1D Convolutional Neural Networks (CNN) and Transformers. This hybrid model achieves end-to-end continuous reconstruction from 1D beam projections to 2D phase space dynamic evolution.
The network is trained on a high-fidelity dataset generated via the BLonD code. It incorporates nonlinear space charge effects based on the machine parameters of the Xi'an 200MeV Proton Application Facility (XiPAF). Results demonstrate the model accurately restores complex phase space topological structures. It effectively captures both high-density cores and low-density edge halos. The model achieves a longitudinal line density projection error under 1% in simulations and under 2% using real Fast Current Transformer (FCT) measurements from the XiPAF facility.
Furthermore, the framework delivers single-frame inference times of 0.109 ms on a GPU and 4.557 ms on a standard CPU. This sub-millisecond processing speed successfully crosses the engineering threshold for online real-time diagnostics. Ultimately, it establishes a reliable new continuous imaging paradigm for automated beam real-time feedback control in high-intensity accelerators.

Speaker: Yixuan Luo (Tsinghua University)

MOP6605_edited_version.pdf

16:00 Recent Advances in Pyapas-Based High-Level Applications for the High Energy Photon Source

To meet the beam commissioning requirements of the High Energy Photon Source (HEPS), a new pure-Python framework named Pyapas was developed, serving as the foundation for all high-level applications (HLAs) at HEPS. Beam commissioning of the Linac began on March 9, 2023, where the HLAs performed exceptionally well, enabling the Linac to achieve its design specifications and pass acceptance. By mid-2023, the development of all booster HLAs was completed, paving the way for beam commissioning in late July, which proceeded smoothly and concluded with successful acceptance in November 2023.In 2024, the team shifted its full focus to developing HLAs for the storage ring. The development phase was completed in June, followed by several rounds of offline testing with the virtual accelerator and integrated system tests. These efforts ensured the readiness of the HLAs, which supported the successful commissioning of the storage ring and the emission of its first light in October 2024.
By the end of 2025, HEPS has met all performance targets and successfully passed process acceptance. This paper provides a concise review of recent progress in HLA development at HEPS, highlights key achievements during booster and storage-ring commissioning, and outlines the roadmap for future work

Speaker: Xiaohan Lu (Institute of High Energy Physics)

16:00 Recent Developments in RF Stabilization at the SPARC_LAB Facility of LNF–INFN

The plasma wakefield acceleration is becoming the most promising acceleration scheme because of its high accelerating gradient and compactness, but it also suffers from unstable operation since the acceleration is accomplished in a short, steep and nonlinear gradient region. This puts forward a very strict synchronization requirement on the subsystems of the entire facility. For the beam-driven scheme, the RF line phase jitter should be less than 20 fs RMS with respect to the facility’s reference master oscillator (RMO). At SPARC_LAB, the RF stabilization technology on RF power stations has been developed for years. These efforts have successfully reduced the phase jitter of the RF line from hundreds of femtoseconds to tens of femtoseconds RMS relative to the RMO. Recent developments on this technology mainly focus on optimizing the fast feedback loop design, together with upgrades of other necessary LLRF components. Dedicated measurements of the prototypes in S-band and C-band both demonstrate reliable and excellent jitter minimization, satisfying the rigid synchronization requirement of beam-driven plasma wakefield accelerators.

Speaker: Xianghe Fang (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati)

16:00 Recent upgrade and operational experience of the vibration monitoring system at TPS

In late 2024, the vibration monitoring system at the Taiwan Photon Source (TPS) was upgraded to enhance stability and usability. The system now includes beamline-floor measurement points and a central measurement center for station management, data export, automated reporting, and web-based access to real-time vibration levels and spectra. During more than a year of routine operation, issues such as abnormal sensor signals, DAQ faults, and station instability were encountered and resolved. The upgrade improves monitoring reliability and enhances the capability to record vibration behavior during events such as earthquakes and typhoons. This paper presents the upgraded system architecture, new analysis functions, operational experience, and examples of post-event vibration analysis.

Speaker: Keng-Hao Hsu (National Synchrotron Radiation Research Center)

MOP6689_edited_version.pdf

16:00 Refined design of the front-end complex for a Muon Cooling Demonstrator at CERN

The muon collider has great potential for enabling high-luminosity multi-TeV lepton–
antilepton collisions provided low-emittance, high-intensity muon beams can be
produced. Ionization cooling is the proposed technique to achieve the required muon
beam emittance. The International Muon Collider Collaboration aims to demonstrate the
integration and reliable operation of a 6D ionization cooling system, including RF
acceleration in strong magnetic fields. This study advances the design of the muon
production and transport systems for a Muon Cooling Demonstrator implemented in the
CERN CTF3 building. Building on previous work, the design is extended to finalise the
beam-preparation section and the matching of the transport line into the cooling channel.
The target–horn model has been further optimised and now incorporates a forced-
convection helium cooling system, providing a more mature and realistic representation.
An extended FLUKA model of the target area is used to assess and optimise shielding
requirements.

Speaker: Paul Jurj (Imperial College London)

MOP1105_edited_version.pdf

16:00 Refinement of tune monitor in TPS booster

The TPS is a newly constructed 3-GeV third-generation synchrotron light source featuring ultra-high photon brightness with extremely low emittance. The stripline electrodes are adopted to replace magnet shakers on the booster synchrotron considering more power strength to excite beam to extract tune. Agilent arbitrary signal generator would provide band-limited, strength-adjustable excite signal.

Speaker: Jui-Che Huang (National Synchrotron Radiation Research Center)

16:00 Remote Clamp RC160T For Restricted Access Environments

Maintenance in hostile environments where human access is limited or prohibited requires remotely operated systems capable of delivering high precision, reliability, and minimal setup time to ensure safe and efficient operation. Tekniker addresses these challenges through its Remote Handling specialization line, developing systems able to perform accurate mechanical tasks within highly constrained spaces, under radiation or in other demanding conditions.
Within this framework, Tekniker has developed the RC160T, a remotely operable clamp intended to minimise human intervention in vacuum installations. The device is built from bronze and stainless-steel components to avoid material activation, is compatible with CF and ISO-K flanges, eliminating the need for modifications existing vacuum lines. The clamping force has been characterised through integrated strain gauges, enabling correlation between torque and effective sealing load. Leak-rate performance, measured according to UNE-EN ISO 20485** using the LT tracer-gas method, achieves values below 1e-12 mbar·l/s. The RC160T operates with a single-axis actuation that can be used manually with a pole or remotely by a robotic system. The clamp has been validated using both conventional CF gaskets and diamond-edge profile gaskets on ISO K flanges. This results in reliable, and tool-friendly solution that enhances system availability while reducing human exposure, maintenance time, and the operational footprint of vacuum-system.

Speakers: Amaia Villa (Tekniker), Andoni Egurrola Areta (Tekniker)

16:00 Repair and improvement of the superconducting magnets of the S3 spectrometer at GANIL

In order to achieve optimal performance in terms of transmission and separation for the S3 spectrometer, the project chose to design superconducting magnets integrating 11 magnetic functions in a single cryostat. There are seven of these magnets, called Superconducting Multipole Triplets, in the spectrometer. The compactness of these magnets makes them remarkable and unique, but has led to significant commissioning difficulties. As the design was very close to the acceptable operating limits, we experienced several breakages and leaks, as well as limitations in terms of nominal current. In this presentation, we will show the important work we carried out to repair the main conductor, improve the robustness of the current leads and feedthrough, and repair the various leaks.

Speaker: Antoine WAGRET QUATROMME (Grand Accélérateur National d'Ions Lourds)

MOP7073_edited_version.pdf

16:00 Representation of mechanical modes spectrum

The static and dynamic Lorentz force detuning (LFD) derive from the sum of many mechanical modes and their interplay with EM radiation pressure. The LFD may give rise to instabilities in which the EM resonance frequency moves away from the “set point” value. The usual analytic theory for the oscillatory instability, and its threshold, are for a single, isolated mechanical mode; not a sum. We want a mathematical representation of the LFD spectrum that is compatible with an “isolated resonance” style of stability analysis, but nevertheless captures the phase-advance properties of a sum of many modes.

Speaker: Dr Shane Koscielniak (TRIUMF)

MOP7301_edited_version.pdf

16:00 Results from the HEPTO combined function permanent magnet

The Hybrid Electromagnet-Permanent Magnet Tuneable Optics magnet has been designed and built as part of the I.Fast collaboration as an energy saving alternative to traditional resistive electromagnets. The prototype magnet has been designed to meet the magnetic field requirements of the combined function dipole-quadrupole (DQ) magnets required for the Diamond-II upgrade. The prototype contains several design features for maintaining and tuning the field strength and quality, including a novel mechanical shimming method, trim coils and passive temperature compensation. We present here the results of the magnetic measurements of the built prototype magnet and demonstrate the ability to tune the field using the design features. We demonstrate that the nominal integrated field strength and homogeneity can be achieved with the permanent magnet solution, representing a 2.3 kW reduction in nominal power consumption compared to the equivalent electromagnet.

Speaker: Alex Hinton (ASTeC, STFC Daresbury Laboratory, Cockcroft Institute)

MOP7165_edited_version.pdf

16:00 RF design progress of the 197 MHz crab cavity for EIC

The interaction region (IR) crab cavity system is a special RF system designed to compensate for the luminosity loss caused by the 25 mrad crossing angle at the interaction point (IP) of the Electron-Ion collider (EIC). The configuration includes six crab cavities in the Hadron (proton or ion) Storage Ring (HSR) - four operating at 197 MHz and two at 394 MHz - installed on each side of the IP, along with one 394 MHz crab cavity on each side of the IP in the Electron Storage Ring (ESR). This paper presents the recent progress in the RF design of the 197 MHz crab cavity, addressing the geometrical constraints, required crabbing voltages, multipole components, and the Higher Order Mode (HOM) power and impedance thresholds.

Speaker: Silvia Verdu-Andres (Brookhaven National Laboratory)

MOP7303_edited_version.pdf

16:00 RF Power Couplers for IFMIF-DONES RFQ

The IFMIF DONES CW RFQ is feed by 8 RF power couplers for a total power capability of 1.6MW. A new set of couplers is going to be produced by INFN as backup solution for long term LIPAC operation and as first candidate for the IFMIF DONES RFQ. The couplers are equipped with cooled brazed alumina RF window. The same RF window design will be used for SPES RFQ.
The physical design of the RF coupler has been performed in an optimization design loop between RF matching, MultiPacting mitigation and thermal structural analysis, with a constant reference to construction feasibility.
The paper describes the sequence of design, production and test of the high-power RF couplers for the IFMIF RFQ. The production status is also presented.

Speakers: Andrea Pisent (Istituto Nazionale di Fisica Nucleare), Francesco Grespan (Istituto Nazionale di Fisica Nucleare)

16:00 RF power transients at injection energy in the FCC-ee high-energy booster

The FCC-ee high-energy booster RF system consists of 112 superconducting cavities at 800 MHz for the operation modes at Z, WW, and H(ZH) energies, with an additional 408 cavities for the t t̄ stage. The first set of working points requires a wide total voltage range from 50 MV to 2 GV. To cover this huge range, Reverse Phase Operation (RPO) will be employed. It groups the cavities into focusing and defocusing families, according to their phase. To achieve the relevant operation modes of the booster and provide sufficient voltage per cavity, the RF power requirements are estimated and minimized analytically with a defined detuning program, including Lorentz force detuning compensation. Additionally, transient power requests of the RF system in the RPO operation are dynamically computed using the BLonD code. The simulations are performed with sparse profiles, to limit the beam observation to the filled buckets. An LHC-like cavity feedback is adapted to the booster characteristics and allocated to both RPO families. The mitigation measures for the power transients are discussed in this contribution.

Speaker: Lina VALLE (European Organization for Nuclear Research)

MOP7055_edited_version.pdf

16:00 RF properties of non evaporable getter coatings in the sub THz range

We report on the measurement of the surface impedance of thin sub-micron non-evaporable getter (NEG) coatings on a copper substrate, as used for distributed pumping in the vacuum system of the Swiss Light Source upgrade (SLS 2.0). Given the low electrical conductivity of NEG, a sub micron thickness with well known properties is required to avoid heat up and beam instabilities. Measurement frequencies around 100 GHz are required to obtain a good measurement sensitivity for these tiny coatings. A quasi-optical test stand based on a Fabry Perot principle uses one spherical mirror containing input and output couplers and a planar NEG coated probe mirror. 3D printing allowed to produce the spherical mirror together with the RF coupler and waveguide flanges in one integral part, which required only minimal additional processing. The setup is calibrated with the help of probe mirrors fabricated from bulk stainless steel and copper. For coated probes, we clearly saw the impedance changes caused by coatings with thicknesses in the 300 to 600 nanometer range and were able to prove their compatibility with the impedance requirements of the accelerator.

Speaker: Micha Dehler (Paul Scherrer Institute)

MOP7017_edited_version.pdf

16:00 RF window Ti coating characterization

Thin titanium coatings were deposited on alumina RF windows at CERN to reduce the secondary electron emission yield. The deposition process was optimized to ensure uniform coverage of the components used in high-power RF systems. Witness samples were characterized to assess their suitability for accelerator applications. Surface resistivity was measured under controlled conditions, while the Secondary Electron Yield was evaluated to determine the effectiveness of the coating in reducing electron emission. Thickness uniformity was characterized through detailed mapping using Rutherford Backscattering Spectrometry at the Laboratori Nazionali di Legnaro, providing spatially resolved information on deposition homogeneity and confirming process reproducibility. These results provide a comprehensive overview of the properties of the titanium coatings and serve as a useful reference for optimizing surface treatments of RF windows in accelerator facilities.

Speaker: Francesco Grespan (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro)

MOP7153_edited_version.pdf

16:00 Selection of transverse diagnostics to measure few-micron beam modulations in the nanopatterned microbunching experiment

A nanopatterned microbunching collaboration has been formed to test the production of electron microbunches by rotating transverse beamlets into the longitudinal plane using the emittance exchange (EEX) beamline of the Argonne Wakefield Accelerator (AWA).-* This mechanism has been suggested, such as by the Compact X-ray Free-Electron Laser (CXFEL) group at Arizona State University, to hold the potential to make short-wavelength free-electron lasers (FELs) more compact. Our collaboration will pattern AWA’s 40 MeV electron beam with a TEM grid to produce micro-scale beamlets that will become mico-to-nano scale microbunches in the longitudinal plane. Characterizing an array of beamlets with a modulation period at the few micron scale and a low, single pC scale total charge presents challenges in achieving the necessary transverse resolution and signal strength. These proceedings will detail the diagnostics explored to characterize these transverse modulations. We will discuss the merits and challenges of each approach in relation to our application, and progress towards demonstrating these desired diagnostics.

Speaker: Rachel Margraf-O'Neal (Argonne National Laboratory)

MOP6355_edited_version.pdf

Poster MOP6355.pdf

16:00 Sensitivity of FCC-ee beam performance to resonance driving terms in the presence of beam–beam interactions

The control of nonlinear beam dynamics is essential for achieving the luminosity targets of FCC-ee, particularly in the presence of strong beam–beam interactions and machine imperfections. Resonance Driving Terms (RDTs) provide a systematic framework to characterize nonlinear dynamics and quantify the strength of resonances excited by nonlinear magnetic elements in the lattice. This contribution presents a sensitivity study of individual RDTs and their impact on beam losses, vertical emittance, and luminosity in FCC-ee, evaluated using tracking simulations including beam–beam interactions. The results establish a ranking of the relative importance of individual RDTs on the performance, providing guidance for future RDT-based correction strategies.

Speaker: Tirsi Prebibaj (École Polytechnique Fédérale de Lausanne)

MOP1040_edited_version.pdf

16:00 SEY reduction using ultrathin TiN/NbN multilayers for accelerator applications

Multipacting and electron cloud formation remain major limitations for the performance of modern particle accelerators. In superconducting radio-frequency (SRF) cavities, multipacting can prevent stable cavity operation and restrict achievable accelerating gradients. In positively charged particle machines such as the LHC, the build-up of electron clouds results in beam instabilities, vacuum degradation, and additional heat loads on the cryogenic systems. Reducing the secondary electron yield (SEY) of vacuum-facing surfaces is therefore a key strategy to mitigate these effects. To mitigate these effects, several strategies have been proposed, in particular the deposition of thin films designed to reduce the secondary electron yield (SEY) of the relevant surfaces.
We investigated the SEY behaviour of ultrathin TiN/NbN multilayers, with particular attention to the influence of both the number of layers and the TiN/NbN stacking sequence. Multilayers composed of individual 3 nm films were deposited by PVD to probe interfacial effects and possible electronic confinement phenomena. SEY measurements performed before and after electron conditioning reveal a dependence on the multilayer architecture. One particular multilayer configuration achieves a significantly reduced SEY, reaching 0.98 after conditioning.

Speaker: Gaël Sattonnay (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

MOP7089_edited_version.pdf

16:00 Simulation Analysis of X‑Ray Pinhole Imaging and Fresnel Zone‑Plate‑Based Beamline for HALF

This work presents a comprehensive simulation study aimed at validating key optical models for X‑ray pinhole cameras and Fresnel zone‑plate (FZP) imaging lines designed for the Hefei Advanced Light Faclilty (HALF). Accurate transverse beam diagnostics are essential for beamline performance, and simplified approximations—such as the square‑aperture pinhole model, Gaussian point‑spread function (PSF), and analytical diffraction models—require rigorous evaluation under realistic conditions.

We perform systematic simulations of a HALF‑configured pinhole camera using both an ideal square aperture (25×25 µm) and a realistic two‑plate tungsten pinhole. Diffraction effects are compared between Fresnel (near‑field) and Fraunhofer (far‑field) regimes by varying source‑to‑pinhole and pinhole‑to‑detector distances. In parallel, a detailed wave‑optical simulation of a Fresnel zone‑plate imaging line is conducted to assess focusing efficiency, spatial resolution, and coherence effects under HALF beam parameters.

This integrated simulation approach supports the optimization of beam‑diagnostic instruments and coherent imaging systems at HALF, ensuring reliable performance from preliminary design to commissioning.

Speaker: Xinru Gao (University of Science and Technology of China)

16:00 Simulation and study of the Muon Cooling Demonstrator Rectilinear Channel in BDSIM

The muon collider has great potential for enabling high-luminosity multi-TeV lepton–antilepton collisions provided low-emittance, high-intensity muon beams can be produced. Ionization cooling is the proposed technique to achieve the required muon beam emittance. The rectilinear cooling lattice used to compress the six-dimensional (6-D) phase-space volume of the beam comprises solenoids for strong focusing, dipoles to generate dispersion, wedge absorbers for differential energy loss, and RF cavities for longitudinal energy restoration. The International Muon Collider Collaboration aims to demonstrate the integration and reliable operation of a 6-D ionization cooling system, including RF acceleration in strong magnetic fields. This paper presents a full implementation of the Muon Cooling Demonstrator 6-D cooling lattice in BDSIM, together with an evaluation of its cooling performance.

Speaker: Paul Jurj (Imperial College London)

MOP1048_edited_version.pdf

16:00 Simulation studies for the nuSTORM facility

nuSTORM (neutrinos from Stored Muons) is a future-generation accelerator-based neutrino facility that is currently being designed to have %-level flux uncertainty which obtains neutrinos from muon decay in a storage ring. nuSTORM will be able to measure ν-A cross-section with great precision for both electron and muon neutrinos. The storage ring will store muons with a momentum range of 1–6 GeV/c covering the flux energy range of major future experiments such as DUNE and T2HK. BSM (Beyond Standard Model) sensitivity can also be expected. Additionally, nuSTORM can pioneer accelerator technologies such as being a testbed for muon colliders, magnet technologies, and beam monitoring. The nuSTORM facility consists of a production straight which transports and decays pions and muons to produce neutrinos and a return arc with a hybrid FFA magnet. This study will cover updates on simulation studies of the storage ring and development of simulation methods.

Speaker: WONJONG CHANG (University of Warwick, STFC Rutherford Appleton Laboratory)

16:00 Simulations and measurements of injection backgrounds at SuperKEKB

SuperKEKB is an electron-positron collider providing beam to the Belle-II experiment. The design luminosity has not yet been achieved, partly due to limited injection efficiency in both rings, which limits the achievable beam current. In addition, the injection process generates significant background in the Belle-II detector, requiring vetoes during data taking that reduce the detector efficiency.
In order to improve the understanding of these issues, the injection process at SuperKEKB has been simulated using the Xsuite simulation framework, including detailed multi-turn tracking and particle-matter interactions in the collimators. The results of these simulations have been used as input for a Belle-II detector simulation to estimate the resulting background levels.
This paper presents the simulation methodology and the comparison with experimental data, collected during the 2025 run, as a prerequisite for future applications of the simulation framework including further optimization of the background at SuperKEKB as well as similar studies for future lepton colliders.

Speaker: Giulia Nigrelli (European Organization for Nuclear Research, Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Sapienza University of Rome)

MOP1016_edited_version.pdf

16:00 Simulations of phase-advance correction for FCC-ee and impact on its performance

The control of the optics in the Future Circular electron–positron Collider (FCC-ee) is a challenging but crucial task for meeting its performance goals. Lattice imperfections, such as magnet misalignments and field errors, introduce distortions in the phase advance between the Interaction Points (IPs), which could affect the Dynamic Aperture (DA) and degrade luminosity, particularly in the presence of strong beam–beam interactions. This work presents simulation studies of modeling such imperfections, quantifying their impact on the optics and in particular on the phase advance between the IPs, and developing correction schemes aimed at restoring the nominal phase advance. Implications for the DA and beam quality are discussed.

Speaker: Tirsi Prebibaj (École Polytechnique Fédérale de Lausanne)

MOP1077_edited_version.pdf

16:00 SMAUG experiments at CERN’s HiRadMat facility for the study of materials used for particle beam windows

The series of SMAUG experiments performed at the HiRadMat facility within the CERN accelerator complex investigated the performance limits of materials suitable for particle beam windows under extreme proton beam conditions. Materials including; Glassy Carbon, Beryllium (grades I-220-H, S-200-FH, PF-60®), and Silicon Nitride (Si₃N₄) were exposed to 440 GeV/c proton beams with total intensities up to 2.8x10^15 protons and beam spot sizes ranging from σ 0.5mm to 0.25mm. Multiple configurations (SMAUG 1, 1.5, and 2) simulated high intensity operational conditions, also replicated previous failures observed in TT66 Be windows. Post-irradiation analysis included leak detection, optical microscopy, SEM, and 3D topology measurements, combined with FLUKA beam energy simulations to demonstrate material performance.

Speaker: Anthony Harrison (European Organization for Nuclear Research)

MOP7107_edited_version.pdf

16:00 Software development of beam diagnostics readout system based on a multi-channel high-speed digitizer

In the upgraded accelerator of the China Spallation Neutron Source Phase II (CSNS-II) project, several multi-channel beam diagnostic detectors are installed, including a Ionization Profile Monitor (IPM) for measuring the injection beam profile and a Multi-Wire Profile Monitor for measuring the target beam profile. In the China Spallation Neutron Source (CSNS), similar multi-channel detectors typically utilize multiple PXIe acquisition cards to construct a PXIe-based signal acquisition system, which suffers from high cost and limited flexibility. This paper presents an alternative signal readout solution using a multi-channel high-speed digitizer to replace the PXIe system. The digitizer incorporates built-in front-end amplification functionality, eliminating the need for separate analog electronics for signal amplification. With a maximum sampling rate of 125 MS/s, it fully meets the sampling requirements for the beam pulse width in the CSNS-II Rapid Cycling Synchrotron (RCS), which ranges from 500 ns to 80 ns. Moreover, the multi-channel signal acquisition system implemented with this digitizer offers high integration and reduced cost compared to the PXIe system, making it an ideal choice for beam diagnostics systems.

Speaker: Renjun Yang (Institute of High Energy Physics)

MOP6623_edited_version.pdf

16:00 SPEAR3 booster response matrix measurement

In this paper, we present the orbit response matrix (ORM) measurements for the SPEAR3 booster obtained using a set of Libera Spark ERXR beam-position processors. The turn-by-turn acquisition capability of these processors enables continuous tracking of the beam trajectory throughout the full energy ramp prior to injection into SPEAR3. This dataset provides sufficient resolution to extract the booster’s optical functions and to perform ORM-based fitting of lattice errors such as quadrupole strength deviations and magnet roll angles in the Accelerator Toolbox (AT) model. The resulting refinements to the machine model have contributed to improved understanding and mitigation of beam-loss mechanisms, thereby enhancing the beam capture from the linac-to-booster (LTB) transport line and injection efficiency into SPEAR3.

Speaker: Donish Khan (SLAC National Accelerator Laboratory)

MOP6374_edited_version.pdf

16:00 Spin tracking and equilibrium polarization computation in Xsuite: implementation and benchmarks

Precise modelling of spin dynamics is essential for the energy-calibration programme of the FCC-ee collider, where resonant depolarization measurements require accurate predictions of polarization buildup and of the spin-tune response to machine errors. We present spin modeling capabilities recently implemented in the Xsuite simulation framework, enabling high-performance six-dimensional tracking of particle trajectories together with their spin motion. The module includes the integration of the Thomas–BMT equation and a linearized computation of the invariant spin field (ISF), obtained from the one-turn linear map. Radiative spin effects are incorporated through the Sokolov–Ternov mechanism and its generalizations, allowing the evaluation of equilibrium polarization and of its buildup time.
The new tool has been benchmarked against the BMAD code for representative lattices, covering both spin-closed-orbit properties and long-term polarization evolution.

Speaker: Giovanni Iadarola (European Organization for Nuclear Research)

16:00 SRF cavity detuning characterization by continuous wavelet transform: a time-frequency analysis

Sustainability is a key issue for both current and future particle accelerators. Superconducting RF cavities with high loaded quality factors play an important role in not only lowering the energy demands of particle accelerators but also the initial investment in RF amplifiers. But the narrow bandwidth associated with this high loaded quality, makes the need to minimize cavity detuning critical to maintain stable and efficient operation. In this context, characterization of microphonics detuning is essential, as it is a major error source, for implementation of effective mitigation schemes to reduce peak and rms RF power requirements.

Here we analyze SRF cavity detuning using the Continuous Wavelet Transform (CWT). Unlike conventional Fourier-based approaches, the CWT enables localized time-frequency decomposition, making it well-suited for identifying transient features that influence cavity behavior. Applying the CWT to measured detuning signals from a TESLA cavity at HoBiCaT testing facility at Helmholtz-Zentrum Berlin allows us to identify dominant detuning frequencies and track their evolution over time. The resulting time-frequency maps offer a more comprehensive understanding of the underlying mechanical environment and can support the development of more robust detuning mitigation and compensation strategies for SRF systems.

Speaker: Joyce Samantha Romero Jiménez (University of the Basque Country)

MOP7036_edited_version.pdf

16:00 SRF2027 Padua - 23rd International Conference on RF Superconductivity

The next SRF2027 conference will be organized by INFN and will be held from Sunday, June 27 to Friday, July 2 at the Padova Congress in Padua, Italy, with tutorial sessions at the University of Milan from June 24 to 26. Guided tours of the INFN National Laboratories in Legnaro and INFN LASA in Segrate will be organized during the event.
The SRF conference series has long provided a vibrant forum for scientists, engineers, students, and industrial partners to present and discuss the latest advances in superconducting radio-frequency technology for particle accelerators. For this 2027 edition, we are delighted to host the conference in Padua, Italy, a historic university city and UNESCO World Heritage site, located near Venice. Since its inaugural event in 1980, the SRF Conference has been held biennially, rotating among Europe, North America, and Asia. Over nearly fifty years, it has become the reference forum where the scientific community presents, explores, and discusses both the fundamentals and the applications of superconducting radio-frequency technology.
The development of SRF technology, initially driven by high-energy physics collider, has pushed accelerating gradients toward the fundamental limits of superconducting materials. This progress has been enabled by increasingly fundamental knowledge on SRF physics and technology, shaped by the lively discussions fostered within this conference series. Over time, superconducting cavity technology has matured and has been widely adopted in large-scale user facilities, spanning electron, proton, and heavy-ion accelerators. In parallel, the conference has evolved to address challenges related to industrial production and reliable, long-term operation in real-world environments. Today, SRF technology is employed not only in major high-energy physics accelerators, but also in compact industrial and medical machines, as well as in applications beyond accelerators, such as dark matter and axion detection, gravitational wave research, and quantum computing. These new challenges have expanded the interest of the SRF community in the study of new theoretical aspects, advanced characterization methods, innovative materials, cutting-edge manufacturing and surface treatment techniques, engaging an ever-growing scientific and technological community.
Continuing this long-standing tradition, SRF2027 will feature invited and contributed talks, poster sessions, and an industry exhibition. The scientific program will be complemented by a range of social events designed to foster informal exchange and collaboration.
SRF2027 will also provide an excellent opportunity for students and early-career scientists to present their work and engage with the SRF community. The conference will be preceded by a series of tutorials, to be held from June 24 to 26 at the historic premises of the University of Milan. A dedicated student poster session will take place on Sunday, in conjunction with the welcome reception, in the stunning setting of the historic cloister of the Abbey of Santa Giustina in Padua.
For organizations interested in supporting the conference and enhancing their visibility, several sponsorship opportunities will be available.

Speaker: Cristian Pira (Istituto Nazionale di Fisica Nucleare)

16:00 SSPA efficiency improvement studies at ALBA in the framework of the RF2.0 project

ALBA is a 3rd generation synchrotron light source and is member of the RF2.0 project, which aims to reduce the carbon footprint of this kind of large research facilities by improving its efficiency, reliability and operational sustainability. In this contribution, we present the work done together with our partner COMMTIA, that has developed the Adaptive Power and Digital Control (APDC) for a 5 kW 1.5 GHz SSPA amplifier, which enables a real-time efficiency optimization by changing dynamically the drain voltage of the transistors while delivering RF power. This is done in two different ways: either the SSPA sets the desired voltage as function of the output power or the Digital Low Level RF system sets the voltage to the SSPA by means of a digital signal. This maximizes the efficiency at each point of operation, ensuring stable performance under the varying load and thermal environments common on accelerator facilities.
The laboratory measurements indicate substantial improvements in efficiency, that comes with the cost of the SSPA linearity gain reduction. These developments show how flexible solid-state RF systems can satisfy demanding high-performance requirements while lowering the energy consumption and carbon footprint of accelerator infrastructures.

Speaker: Mr Pol Solans (ALBA Synchrotron (Spain))

MOP7011_edited_version.pdf

16:00 Standard and microbeam LINATRONs by Varex Imaging Corporation

At Varex Imaging Corporation, High Energy Systems (HES) Department staff with help and support of our Production and Imaging groups continue adding new features to our LINATRON linear accelerator (LINAC) systems and transitioning new developments to our products. HES is at the final stages of productizing our usual LINATRONs, equipped with our new, in-house developed and built Accelerator Beam Centerlines (ABC). The products we offer today match or exceed the older products specifications, which were offered before we established our own ABC development and production line. In addition, we are making good progress on our new Microbeam LINATRON (MBL) systems, and we present the latest results on our MBL production prototypes. Our 6 MeV MBL6 prototype has been packaged, and it is under extensive testing and qualification process, getting ready for demonstration to our customers and for delivery. The similar packaging of our 3 MeV and 9 MeV LINATRON systems offers options of Ultra Low Leakage (ULL) shielding and of an integrated design packaging, now both for our security LINACs and for NDT LINACs under development.

Speakers: Dr Andrey Mishin (Varex Imaging (United States)), Rich LaFave (Varex Imaging (United States)), Stanislav Proskin (Varex Imaging (United States))

MOP8303_edited_version.pdf

16:00 Static and dynamic field characterisation of the super proton synchrotron bending magnets

To ensure precise control of field quality in normal-conducting accelerator magnets, it is essential to develop models that accurately represent magnetic hysteresis during operational cycles. This study focuses on the dipole magnets of the CERN Super Proton Synchrotron (SPS) and investigates how variations in operational cycles produce different hysteresis and dynamic patterns in the integrated main magnetic and higher-order field multipoles. A combination of various magnetic field measurement systems was employed to evaluate the magnetic field quality, enabling direct observation of history dependence and reproducibility. Three regimes are identified: a history-dependent reversal curve along the ramp, eddy-current settling during end-of-ramp transients, and a rate-independent transfer function at the plateau. The analysis covers the integrated dipole and sextupole components, distinguishing rate-dependent eddy current effects from quasi-static hysteretic contributions. Two pre-cycle patterns currently used in operation are compared: a \SI{200}{GeV} cycle and a \SI{26}{GeV} cycle introduced in 2026 within the CERN Efficient Particle Accelerator (EPA) initiative. The aim is to provide a quantitative single-magnet assessment of this change of operation.

Speaker: Alberto Bellelli (European Organization for Nuclear Research, TU Wien)

MOP7070_edited_version.pdf

16:00 Status of magnets for ALBA II project: design, prototyping and production plans

The upgrade project of the ALBA Synchrotron Light Source is gaining momentum following the official approval of the required funds at the end of 2025. The design of the magnets for the new ALBA II storage ring began in 2021 with the launch of a comprehensive prototyping program aimed at developing and validating the various magnet types required by the new multi-bend achromat (MBA) lattice. The first prototype magnets became available at the end of 2025 and are currently being characterized at ALBA’s magnetic measurements laboratory to assess their performance against the design specifications, as well as to investigate critical aspects such as magnetic cross-talk and mechanical integration between neighboring magnets. In parallel with prototype fabrication, the magnet designs have continued to evolve to keep pace with the successive refinements of the ALBA II lattice over the past years. The lattice is now approaching its final configuration, and together with the lessons learned from the prototyping campaign, this will enable the completion of the magnet designs during 2026. This contribution presents the current status of the magnet prototyping program and outlines the pathway toward the final magnet designs, emphasizing the main challenges encountered and the technological solutions implemented.

Speaker: Jordi Marcos (ALBA Synchrotron (Spain))

MOP7065_edited_version.pdf

16:00 Status of Osprey: A Framework for Agentic AI in Control Systems

Operating large-scale scientific facilities requires coordinating diverse subsystems, translating operator intent into precise hardware actions, and maintaining strict safety oversight. Language-model agents offer a natural interface for these tasks, but most existing approaches are not yet reliable or safe enough for production use. We introduce Osprey, a framework that wraps a coding agent in a control-room operator interface, a tool surface that reaches hardware through pluggable connectors for the control system used in our community, and a first-class component for natural-language search of facility electronic logbooks. The agent itself is treated as a replaceable component: operator interface, safety policy, tool servers, and connectors stay under facility control, while the agent backend can be swapped as the AI ecosystem evolves. A declarative build-profile mechanism lets each facility maintain its own configuration without forking the shared framework, keeping deployments reproducible across updates. Osprey has been deployed at several DOE accelerator facilities through the MOAT seed effort within the Genesis~Mission. This paper presents the current framework architecture and reports on the substantial evolution Osprey has undergone over the past year.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

MOP6322_edited_version.pdf

16:00 Status of the cryomodule tests as a part of Polish in-kind contribution to the European Spallation Source (ESS) realized by IFJ PAN

The European Spallation Source (ESS), as one of the complex accelerators require installation and commissioning of many systems and components. One of them is the accelerator which is composed with the cryomodules uses to accelerate of the particles. Taking into account that ESS is one of the most technological advanced accelerators in the world we can expect also that accelerator is very complex and advanced part of this research infrastructure . Among other things three types of the cryomodules: spokes, medium- and high-beta are used to assembly accelerator line. In 2017 first engineers from the Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Science (IFJ PAN) arrived to Lund in order to start execution of IFJ PAN contribution to this project. In total 31 cryomodules have to be tested and prepared for assembly in the tunnel as a part of the accelerator line. In this paper the current status of the tests as well as early stage of the optimization process regarding test program for cryomodules tests is showed. The main focus is done on the procedures and quality aspects, required skills and challenges occurring during the tests work; inter alia: incoming inspection, tests before installation in the bunker, preparation of the cryomodules for the test, test in the bunker, outgoing inspection. A cutting-edge RF cryomodules and systems required the special skills and the right approach to quality which is provided by engineers and technicians from IFJ PAN.

Speakers: Dariusz Bocian (Institute of Nuclear Physics, Polish Academy of Sciences), Jacek Swierblewski (Institute of Nuclear Physics, Polish Academy of Sciences)

MOP7155_edited_version.pdf

16:00 Status of the High Q-High G R&D activities on SRF cavities at INFN LASA

INFN LASA started an R&D activity dedicated to the development of knowledge needed to understand how to improve SRF cavity performances to reach High Q and High G values to accomplish the sustainability and cost reduction requests, as needed for the future large particle accelerators. This R&D activity, funded by INFN, is also enriched by synergies with other LASA activities as PIP-II low beta cavity production, the participation to ILC Technology Network, and by the LASA experience in SRF cavity industrialization developed during the large-scale production of the Eu-XFEL and the ESS SRF cavities. First results obtained on 1.3 GHz single and multi-cell cavities, and the status of the upgraded LASA infrastructures for Vertical Test are presented and discussed.

Speaker: Daniele Sertore (Istituto Nazionale di Fisica Nucleare, Laboratori Acceleratori e Superconduttività Applicata)

MOP7034_edited_version.pdf

16:00 Status of the rapid cycling synchrotron optics

The spin-preserving Rapid Cycling Synchrotron (RCS) is an integral component of the Electron-Ion Collider (EIC) complex. It will accelerate 750 MeV electrons from the Beam Accumulator Ring (BAR) to 5, 9, or 18 GeV, as required by the Electron Storage Ring (ESR), all while preserving the polarization. We discuss here the design considerations and the current optics solution, including considerations related to dynamic aperture and spin preservation as well as a reduced-cost RCS for operations to 9 GeV.

Speaker: Vincent Schoefer (Brookhaven National Laboratory)

MOP1302_edited_version.pdf

16:00 Stretched wire calibration for beam position monitors with 2x Thru de-embedding

Calibration with stretched wire on a test bench is widely used for beam position monitors. Addressing impedance mismatches at both ends of the system is difficult, especially at high frequencies exceeding 100 MHz. Tapered pipes are sometimes utilized for better impedance matches which is difficult for applying to the BPMs, because the wire position moves in horizontal and vertical directions. To eliminate mismatch effects more efficiently in this system, we propose applying 2x Thru de-embedding and demonstrate its effectiveness through electromagnetic simulation using CST Studio Suite.

Speaker: Takeshi Toyama (High Energy Accelerator Research Organization)

MOP6648_edited_version.pdf

16:00 Studies of crystal and amorphous collimation of lead, oxygen and neon beams at LHC

The Large Hadron Collider (LHC) at CERN operates with lead-ion beams for about one month each year, requiring a high-performance collimation system to protect the machine from beam losses. The baseline ion-collimation scheme includes crystal collimation. In 2025, additional ion runs were carried out using oxygen and neon beams, enabling the first experimental comparison of collimation performance between crystal-based and standard systems for these lighter ions.
This work presents a comparative review of measured and simulated collimation performance for lead, oxygen, and neon ions at the LHC using both standard and crystal collimation techniques. The results offer a valuable benchmark for simulation tools used to predict collimation efficiency and provide key input for future LHC ion runs, where ion species other than lead are being considered.

Speaker: Marcin Patecki (Warsaw University of Technology)

MOP1029_edited_version.pdf

16:00 Study and mitigation of radiation effects in the LHCb underground areas

During the 2024 and 2025 LHC proton-proton runs, the LHCb experiment, following its upgrade, achieved a substantial increase in delivered luminosity compared to previous years, exceeding the level of 10 fb-1 per year. While this enhancement greatly expands LHCb’s physics reach, it also leads to a marked rise in radiation levels in the experimental insertion region, originally designed for a significantly lower luminosity target.
Throughout the 2024 p-p operation, several failures of electronic racks and cryogenic sensors, mostly attributed to single-event effects (SEEs), were observed around the LHCb cavern and caused tens of hours of LHC downtime.
This work presents a benchmarking of dedicated FLUKA simulations, used to quantify the radiation levels and identify possible mitigation measures, against measurements by the Battery Radiation Monitors (BatMons). The study guided the relocation of sensitive equipment and the installation of additional shielding in specific underground areas hosting critical electronics, effectively reducing radiation exposure during the remainder of Run-3. Finally, possible improvements for shielding are also discussed in view of Run-4.

Speaker: Roberto Cala' (European Organization for Nuclear Research)

MOP1006_edited_version.pdf

16:00 Study and mitigation of transient beam loading in the double RF system of ALBA II

ALBA, a 3rd generation synchrotron light source in Barcelona, Spain, is currently preparing its upgrade to the 4th generation low emittance machine ALBA II. As part of this upgrade, an active normal conducting harmonic RF system will be installed to improve beam lifetime. However, discountinuities in the filling pattern, such as ion clearing gaps, induce RF cavity voltage variations along the revolution period. This effect, known as transient beam loading (TBL), severely degrades the bunch lengthening performance of the double RF system.
In this contribution, we present a semianalytical study of the TBL effect in ALBA II as a function of gap size, together with a mitigation strategy. The results show that, by modulating the power delivered to the main and harmonic RF cavities at the revolution frequency, the impact of TBL can be effectively mitigated, limiting the degradation of the bunch lengthening performance to 2–18% for gap lengths ranging from 2–11%.

Speaker: Mr Pol Solans (ALBA Synchrotron (Spain))

16:00 STUDY OF MULTIPACTOR DISCHARGE IN THE X-BAND RESONATOR FOR THE ASTERIX PROJECT

Asterix project a worldwide collaboration involving SLAC, CERN, INFN-LNF, KEK, and Tsinghua University, focused on the study and optimization of advanced X-band (11–12 GHz) accelerating structures. These structures, made of hard copper to ensure better high-gradient performance compared to soft copper, employ various geometries such as open-type cells and use alternative, braze-free joining techniques like TIG welding. The study is driven by the demand for high-gradient accelerating structures capable of sustaining gradients above 100 MV/m, which are essential for the next generation of linear accelerators used in research, industrial, and medical applications. An important part of this work is the numerical investigation of multipacting (MP) under different accelerating gradients and geometrical parameters of the quarter– cell model. Simulations performed using CST Studio Suite provided detailed information on how variations in the electromagnetic field amplitude and geometry influence the possible occurrence of MP, allowing for optimization of the structure design and ensuring reliable high-power operation.

Speaker: Zhicheng Huang (University of Science and Technology of China)

16:00 Study of quench margins for betatron Halo losses with new HL-LHC collimation optics

The High-Luminosity Large Hadron Collider (HL-LHC) will mark a new phase of LHC operation, aiming to reach an integrated luminosity of 3000 fb$^{-1}$ over 10 years of operation. A key element to achieve the target luminosity is the beam intensity increase, nearly doubling the number of protons per bunch compared to the initial LHC design. This increases the load on the collimators protecting against beam losses, particularly in the betatron cleaning insertion region (IR7), a multistage collimation system responsible for beam halo cleaning. Particles intercepted here may undergo diffractive scattering and propagate for hundreds of meters, reaching the adjacent dispersion suppressor (DS) sections. To assess the impact of these losses, FLUKA simulations have been performed to predict the power deposition in the superconducting DS magnets on both sides of IR7. Accurate modelling of these losses is essential to ensure safe machine operation and to optimize beam loss monitor thresholds, minimizing unnecessary protective beam dumps. In this contribution, we present shower simulation studies for the latest HL-LHC collimation optics (v1.6), with improved cleaning and impedance in IR7, and compare them to the previous one (v1.5).

Speaker: Helene Guerin (European Organization for Nuclear Research)

MOP1001_edited_version.pdf

16:00 Study of the impact of BFPP losses in the LHCb insertion

Besides its proton–proton physics programme, the LHC operates with 208-Pb ion beams colliding in its four experiments. At the interaction point, bound-free pair production (BFPP), occurring when an electron produced in an electromagnetic interaction is captured by one of the colliding nuclei, is one of the most critical processes in terms of beam losses. In fact, BFPP leads to the creation of a secondary beam with a well-defined change in magnetic rigidity, producing localized power deposition in the dispersion suppressors, possibly causing a magnet quench without proper mitigation measures.
Differently from the ALICE insertion, where two dedicated collimators were installed to protect the superconducting magnets, and the ATLAS and CMS ones, where BFPP losses can be displaced by an orbit bump into an empty cryostat, the LHCb insertion optics only allows for orbit bumps broadening the BFPP loss distribution, so as to reduce the peak power load on the concerned magnets.
This study investigates the resulting power density in the magnet coils and benchmarks the simulation framework against beam loss monitor (BLM) data recorded during Run-3, in order to set a safe luminosity limit.

MOP1020_edited_version.pdf

16:00 Study of the Impedance-related instabilities in the FCC-ee damping ring

The design of the FCC-ee damping ring is progressing,
with ongoing optimisation of beam parameters and key accelerator systems.
Accordingly, the coupling impedance model is updated to reflect the latest vacuum chamber and hardware layouts.
In parallel, the estimates of collective effects and
impedance-related instabilities are being refined.
This paper presents the current wakefield and impedance models for the
FCC-ee damping ring and reports the results of the respective instability studies, including possible mitigation strategies.

Speaker: Shalva Bilanishvili (Istituto Nazionale di Fisica Nucleare)

MOP1106_edited_version.pdf

16:00 Study of the touschek effect in the FCC-ee

The Future Circular electron-positron Collider (FCC-ee) is a design study for a 90.7 km circumference high-luminosity and high-energy e+e- collider. In electron and positron machines, the Touschek effect can cause large transverse-to-longitudinal momentum exchange, leading to particle losses that can limit the beam lifetime and produce distinct beam loss patterns. A quantitative assessment of this mechanism is therefore essential to identify regions potentially exposed to Touschek-induced losses and to determine its impact on the beam lifetime relative to other lifetime-limiting processes. This paper presents a study of the Touschek effect in the FCC-ee, performed using a Monte Carlo Touschek-scattering simulation routine newly implemented in the Xsuite framework. The results include Touschek-lifetime estimates for the FCC-ee and an evaluation of the arising beam loss patterns. The performance of the FCC-ee beam collimation system to safely dispose of Touschek losses is also assessed.

Speaker: Lise Pauwels (European Organization for Nuclear Research)

MOP1021_edited_version.pdf

16:00 Superbends for diffraction-limited light sources: review and recent advances

All third generation synchrotron radiation sources are currently planning upgrades toward diffraction-limited storage rings with brightness close to the theoretical limit and higher hard-x-ray production. In these new photon sources superconducting bending (superbending) magnets may play an important role to extend the useful photon energy range. The radiation produced by superbending magnet is an order of magnitude higher in photon brightness and flux than that produced by a normal conducting bending magnet, making it a superior source of hard x-rays.

As an example, in the framework of the Elettra 2.0 Project, a new superbending magnet is under development with an innovative compact design integrated with quadrupole side magnets. The 6T superbending magnet will replace a normal conducting 1.4T magnet. The magnetic design is combined with novel cryogenic solutions that combine the benefits of a liquid-helium cooled inner magnet with a liquid-helium-free upper cooling stage. A novel C-shaped design will allow to slip in and slip out the magnet from its position on the storage ring vacuum chamber. The NbTi Superconducting magnet will work at 3.5K conduction cooled, thanks a system of heat exchanger connected to a subcooled Helium bath.

Speaker: Dr Marco Modica (Elettra-Sincrotrone Trieste S.C.p.A.)

MOP7079_edited_version.pdf

16:00 Superblock-based SCILAB–Xcos simulation of electron radiation intensity for multiple undulator schemes

Abstract: A SCILAB Xcos model has been redesigned using Super Blocks to simulate electron trajectories in different undulator schemes. The use of Super Blocks simplifies the model structure, reduces configuration complexity, and enhances modularity for further extension. This improvement allows easy modification of parameters and undulator configurations without rebuilding the complete model. The study is further extended to calculate radiation intensity and analyse spectral characteristics at various electron beam energies. Comparison of spectra software demonstrates the accuracy and reliability of the developed Super Block–based Xcos model for studying undulator radiation and free-electron laser characteristics.

Speaker: Ms Mahazbeen Sayed (Rajiv Gandhi Technical University)

16:00 SuperKEKB Beam Transport Tracking and Dynamic Aperture Comparison as an approximation for injection efficiency

A new Energy Compression System (ECS), consisting of four RF cavities, was installed in the SuperKEKB electron transfer line (BTe) during the 2025 summer shutdown. Optimising BTe performance using full multi-turn injection simulations is computationally demanding. To accelerate this process, we compare the beam tracked through BTe — including the ECS — to the dynamic aperture of the High-Energy Ring lattice obtained from Xsuite simulations. The SAD lattices were converted to Xsuite and benchmarked to ensure consistency between the two frameworks. This method provides a fast, first-order estimate of the expected injection efficiency by optimising the survival fraction through the evaluation of particle action amplitudes, while also accounting for physical apertures. Radiation effects and a tapering can be optionally included. Different injection schemes are supported within the same framework. Together, these elements enable rapid optimisation of the ECS parameters with significantly reduced computational cost.

Speaker: Nikita van Gils (European Organization for Nuclear Research, University of Groningen)

MOP1080_edited_version.pdf

16:00 Swiss Light Source 2.0 vacuum system conditioning and first year of operation

After more than two decades of user operation, the Swiss Light Source (SLS) entered a major upgrade phase in October 2023, targeting a 40-fold reduction of electron-beam emittance via a new 7-bend achromat lattice at 2.7 GeV. The vacuum system, central to machine performance, was completely rebuilt to meet the stringent requirements imposed by the compact lattice. The new storage ring vacuum consists of an 18 mm aperture, 288 m long system assembled from over 500 chambers.
Following 14 months of installation, first beam was achieved in January 2025. Vacuum conditioning represented a critical milestone, enabling delivery of light, with nominal beam current, to the first experiments in April. This contribution presents the vacuum conditioning of the SLS 2.0 storage ring during this first year of operation, from initial commissioning to user operation.

Speaker: Romain Ganter (Paul Scherrer Institute)

MOP7113_edited_version.pdf

16:00 Synchrotron Radiation Levelling at the Future Circular Hadron Collider

At the proposed future circular hadron collider, FCC-hh, the strong synchrotron radiation emitted inside the cold superconducting magnets represents a significant heat load, which is likely to limit the total beam current. This contribution discusses a new approach, namely synchrotron radiation power levelling: The idea is to adjust the beam energy during a physics store, either continually or in a few discrete steps, while the beam current decreases due to proton burn-off in collision, so as to keep the synchrotron radiation power at or below a certain limiting value. In this way, both peak and integrated luminosity of the FCC-hh are increased, compared with operation at a fixed beam energy, thereby maximising the physics output.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

MOP1055_edited_version.pdf

16:00 Synchrotron XRF Characterization of Lithium in Pyrite-Bearing Shales in North-East India: Advanced Materials Analysis for Unconventional Resources.

The global transition to sustainable energy demands validation of unconventional lithium reservoirs, particularly pyrite (FeS₂) within organic-rich black shales (Bhattacharya et al., 2024). This study proposes the application of Synchrotron X-ray Fluorescence (XRF), an accelerator-based, high-resolution materials characterization technique, to investigate sediment-hosted lithium enrichment in the Makum Coalfield and surrounding formations of Upper Assam, North-East India (Misra ,1992).Building on evidence that lithium substitutes for Fe²⁺ or occupies vacancy sites within framboidal pyrite, Synchrotron XRF will generate precise spectroscopic data to confirm the measurable lithium concentration and its binding mechanism in this regional geological setting. The research aims to establish a strong experimental and theoretical foundation using accelerator science, thereby advancing materials science and supporting national efforts toward sustainable energy resource assessment.

Speaker: Zahid Mamud (The Assam Royal Global University)

16:00 Target complex design for a high intensity beam dump facility in the north experimental area at CERN

The Search for Hidden Particles (SHiP) is a new high-intensity fixed-target experiment to be located within the Experimental Cavern North 3 (ECN3) at CERN’s North Area, utilising a 400 GeV proton beam from the SPS. The construction of a Beam Dump Facility (BDF) target complex is required for the successful operation of SHiP. It comprises an underground target station within the Tunnel Target Cave 8 (TCC8) cavern, adjacent to ECN3, which will house a 1.5 m-long, 0.25 m-diameter tungsten target, and an above ground service building that includes the target cooling systems and waste package infrastructure. The required infrastructure to investigate target failures, including the cutting of spent targets and other CERN legacy waste in view of their packaging for disposal, has been studied. This contribution presents the current design status of the target complex, including radiation protection, remote handling, utilities and cooling/ventilation systems, installation and operation procedures, maintenance and decommissioning plans, and sustainability aspects.

Speaker: Thomas Banks (European Organization for Nuclear Research)

MOP7138_edited_version.pdf

16:00 Target design considerations for LINAC-based Astatine-211 production

Astatine-211 (At-211) is a highly promising radionuclide for Targeted Alpha Therapy, particularly for the treatment of metastatic cancers. However, its clinical adoption remains limited by production challenges. At-211 is typically produced by irradiating bismuth targets with 28-30 MeV alpha particles. Conventional cyclotrons are commonly used for this purpose, although their beam currents rarely exceed 0.1 mA, thereby significantly limiting achievable production yields. Linear accelerators (LINACs) offer an attractive alternative due to their potential for substantially higher beam currents, in the mA range. The Tera-Care Foundation is developing a dedicated high-power target system designed to operate under kW-level power deposition and a pulsed-beam structure. Initial analysis focus on estimating thermal loads, energy deposition profiles, and resulting temperature distributions to determine safe operating limits and prevent material degradation. This work establishes the foundational design framework required to enable reliable, high-power production of At-211 using LINAC technology.

Speaker: Tania de Melo Mendonca (Tera-Care Foundation)

MOP7140_edited_version.pdf

16:00 TDC-Based Phase Measurement for the Radio Frequency System of a Synchrotron Radiation Accelerator

Maintaining a constant phase difference between the reference (Ref) and cavity voltage sampling (Pt) signals is critical for stable operation of the Hefei Light Source (HLS) storage ring's RF system. This requires high-precision real-time phase detection capable of identifying lead or lag, to quickly restore the preset phase after startup or recovery, and to maintain the relationship between the beam synchronous phase in the low-level RF (LLRF) loop and the bunch-by-bunch feedback system. Conventional phase detection methods, based on either phase detector chips or the CORDIC algorithm, face inherent drawbacks. The former has limited accuracy (> ±2°) and needs extra circuitry to determine phase lead/lag, increasing design complexity. The latter requires a high-speed data acquisition system and dedicated processing algorithms, significantly increasing system complexity and cost. To overcome these limitations, this paper proposes a novel phase detection scheme using a Time-to-Digital Converter (TDC) implemented in a Field-Programmable Gate Array (FPGA). The design employs multi-phase TDC and averaging techniques, enabling fast and accurate measurements immune to transmission line delays. The system achieves a phase resolution of 0.359°, requires only one-time calibration, and reliably meets long-term online phase detection needs for the HLS.

Speaker: xiao qu (University of Science and Technology of China)

16:00 Technological innovation for next-generation particle accelerators: key outcomes of the I.FAST project

Next-generation particle accelerators demand innovative technologies able to meet the performance and sustainability requirements of particle physics and applied science, while ensuring high efficiency and reduced costs for industrial and societal applications.
The I.FAST (Innovation Fostering in Accelerator Science and Technology) Project, supported by the European Commission under the Horizon2020 program, has fostered progress in the accelerator community by developing a portfolio of breakthrough technologies and strategic roadmaps for future research infrastructures, such as energy-frontier hadron and lepton colliders, and for medical and environmental applications. The project contributed to the development of novel accelerator designs – including multi-TeV muon colliders, plasma-based accelerators, and high-brightness synchrotron light sources – as well as advanced materials, high-performance components, and cutting-edge manufacturing and diagnostic tools. These efforts collectively aim to improve the energy-efficiency, sustainability, affordability, and compactness of future facilities.
Key outcomes include novel radiation-resistant beam window and absorber materials, stabilization tools for laser accelerators, C- and X-band RF devices for free electron lasers, low-loss LTS and high-temperature superconducting CCT magnets, innovative SRF cavity fabrication and coating methods, additively manufactured linac structures, and high-efficiency klystrons and permanent magnets.

Speakers: Maurizio Vretenar (European Organization for Nuclear Research), Prof. Toms Torims (European Organization for Nuclear Research)

MOP7185_edited_version.pdf

16:00 Test-bench measurement of power-supply, magnet, and vacuum-chamber bandwidth at NSLS-II

In 2019, the NSLS-II fast orbit feedback (FOFB) system was upgraded by reducing BPM and Cell Controller latency, increasing the closed-loop bandwidth from about 250 Hz to 400 Hz. The dynamic behavior of the power supply, magnet, and vacuum chamber, however, had not been directly measured and was treated as a lumped delay. To provide baseline parameters for the NSLS-IIU upgrade, we developed a dedicated test bench and remeasured these components. The existing fast-corrector power supplies show bandwidths of about 4.5 kHz horizontally and 1.5 kHz vertically, while the magnet and chamber responses are near 10–15 kHz with an overall response time of about 10 µs. We also characterized a newer power-supply regulator design and tuned it to achieve a 6 kHz bandwidth in both planes for use in the upgraded FOFB system. Incorporating these measurements into a physics-based model yields good agreement with observed system behavior. These results provide the first full experimental characterization of the fast-corrector chain at NSLS-II and establish the baseline for designing next-generation hardware for NSLS-IIU.

Speaker: Guimei Wang (National Synchrotron Light Source II)

MOP6376_edited_version.pdf

16:00 The beam stops for the ESS superconducting linac

For the ESS superconducting linac in Sweden, four compact beam stops were designed instead of bulky beam dumps. The beam stops dump protons either up to 100 MeV or 250 MeV; the most demanding beam modes have an average beam power of 700 or 1100 W, respectively.
The beam stops are water-cooled and moved by pneumatic actuators.
The beam stops were designed at the ESS in Sweden and manufactured by Proactive R&D in Spain. The assembly, acceptance tests and metrology measurements were performed in ISO-5 cleanrooms, before the installations in the particle-free environment next to superconducting cavities of the ESS linac.
This contribution summarizes the assembly, testing and operational experience.

Speaker: Artur Gevorgyan (European Spallation Source)

MOP7098_edited_version.pdf

16:00 The Canted Cosine Theta HTS sextupole demonstrator of FCC-ee

A single-aperture, two-layer Canted-Cosine-Theta (CCT) sextupole magnet using high-temperature superconducting (HTS) ReBCO tape has been developed for the short straight sections (SSS) of FCC through the FCCee-HTS4 project. The magnet was designed, manufactured and tested under cryogenic conditions. Two HTS tapes from two manufacturers have been qualified for this specific application. Design and manufacturing details and cryogenic temperature measurements are presented. This demonstrator represents the first HTS CCT magnet ever constructed.

Speaker: Francesco Bardi (European Organization for Nuclear Research)

MOP7081_edited_version.pdf

16:00 The CYREN project: Refurbishment of the GANIL cyclotrons facility

For over 40 years, the GANIL facility has been supplying stable beams (carbon to uranium, 60 keV/A to 95 MeV/A) and low- and high-energy radioactive ion beams for fundamental, applied and industrial research from a set of 5 cyclotrons.
Since 2010, due to the SPIRAL2 construction and compliance projects associated with the French safety regulations, the cyclotrons maintenance and refurbishment were reduced to a bare minimum, and as a consequence the failure rate increased over the years.
Present scientific and industrial demand for GANIL cyclotrons beams, and projection for future demands over the years to come, request GANIL to guarantee the operation over the next 20 years or more. Therefore an ambitious renovation program, the CYREN (Cyclotrons Renovation) project, was launched in 2024.
This article covers the progress of this project, detailing the challenges, partly due to the diversity of the different installations, the uniqueness of the equipment and the sometimes aging, implemented technologies. The project covers a broad variety of equipment from the 5 cyclotrons, beam lines, the associated experimental caves, building infrastructures, technical utilities and the safety, security and radiation protection systems.

Speaker: Pascal Anger (Grand Accélérateur National d'Ions Lourds)

MOP7142_edited_version.pdf

16:00 The detail design of a twin-axial type FE-FRT for SASE

A Twin-axial type Ferro-Electric Fast Reactive Tuner (FE-FRT) is under development for the SASE, aiming to provide a fast and efficient microphonics suppression. The tuner consists of two magnetically coupled cylindrical resonators operating out of phase. In high-frequency FE-FRT, the temperature rise may limit the tuning range. The twin-axial configuration doubles the tuning range for the same temperature rise in the ferroelectric wafers. A key innovation of this work is the use of CST eigenmodes to rapidly optimize the figure of merit (FoM) of the FRT tuner, with some approximations, by sweeping the parameter space, including the FE wafer dimensions and cavity geometry. The thermal analysis has also been performed to assess the temperature rise during operation.

Speaker: Hongping Jiang (Lancaster University)

MOP7043_edited_version.pdf

16:00 The development of new digital BPM signal processor for SSRF

As part of the intelligent upgrade, Shanghai Synchrotron Radiation Facility (SSRF) requires the digital BPM signal processors (DBPM) including White Rabbit timing signal, to enable intelligent beam commissioning. A new digital BPM processor was developed for SSRF to fulfil this requirement. The processor consists of a digital signal processing motherboard and an RF signal conditioning and sampling daughterboard. The motherboard using an MPSoC FPGA as a system controller and signal processing unit, an FMC slot is designed for the White Rabbit timing card. Daughterboard generates a pilot-tone signal for drift compensation. The resolution of the close orbit data is 10 nm, much better than the requirements. The development and integration of all processor functions have been completed, and ready for the upgrade project.

Speaker: Longwei Lai (Shanghai Advanced Research Institute)

MOP6640_edited_version.pdf

16:00 The development of novel beam diagnostics for low-MeV protons

In charged particle therapy, high energy layer switching times prolong beam delivery time, limiting treatment efficiency and accuracy. The TURBO (Technology for Ultra-Rapid Beam Operation) project aims to build a low-energy (0.5-3 MeV) demonstrator beamline for proton therapy with a large momentum acceptance (±42%), enabling rapid delivery over the full clinical energy range, alleviating this bottleneck. Novel beam diagnostic instrumentation is required to monitor key parameters of the beamline constructed for the University of Melbourne’s Pelletron accelerator, which operates at low energies and high current densities. We develop a pepper-pot mask-based method to measure beam phase space distribution and quantify the emittance, and a multi-layer Faraday cup (MLFC) to measure energy distribution. This work now enables the completion of the beam shaping section, and integration of a fixed-field, closed-dispersion beam transport section, key next steps toward assessing TURBO’s potential to shorten beam delivery times.

Speaker: Adam Steinberg (The University of Melbourne)

MOP6614_edited_version.pdf

16:00 The first fully automated analysis of the Hardware Commissioning tests for superconducting circuits at the LHC

The superconducting magnet circuits of the Large Hadron Collider (LHC) at CERN undergo a commissioning campaign at regular intervals, referred to as Hardware Commissioning (HWC), to validate magnet powering and protection functions. During each campaign, more than 1,500 circuits must be commissioned, requiring the execution and analysis of several thousand powering tests. Historically, this process relied on legacy or manual tools, resulting in high workload and sometimes inconsistent results.

To streamline the validation process, a Python-based automated analysis framework has been developed within the Signal Monitoring (SigMon) project over the past two years. The 2026 HWC campaign marked the first time this automated analysis was applied to all powering tests across the superconducting magnet circuits of the LHC. This paper describes the SigMon analysis framework, reports on the 2026 HWC campaign, evaluates the impact of automation, and presents key circuit performance findings.

Speaker: Agnieszka Chmielinska (European Organization for Nuclear Research)

MOP7082_edited_version.pdf

16:00 The Linear Ghost Collider: an efficient Higgs Factory

A 550 GeV centre-of-mass Higgs factory is presented, the
Linear Ghost Collider (LGC). Acceleration and deceleration
are performed within SRF linacs where the bunches trans-
ported are net neutral, comprising equal charges of electrons
and positrons, termed ghost bunches. Within these, one
charge partner accelerates, and the other decelerates. En-
ergy is recovered after a collision, and all particles recycled.
An accompanying paper - Ghost Collider (GC) - introduces
this concept. LGC comprises an alternative configuration to
GC that eliminates turn-around arcs. This enables a large re-
duction in energy lost to synchrotron radiation, and in bunch
degradation, in comparison to GC. Two variants of LGC
are presented: a pulsed version realisable with proven SRF
technology with instantaneous luminosity $35 \times 10^{34}$ cm$^{−2}$
s$^{−1}$ @ 100 MW electrical power; and a continuous-wave
(CW) version based on expected parameters for thin-film
Nb$_3$Sn-on-copper SRF technology, capable of $348 × 10^{34}$
cm$^{−2}$ s$^{−1}$ @ 160 MW electrical power.

Speaker: Dr Peter Williams (STFC Daresbury Laboratory, Cockcroft Institute)

MOP1022_edited_version.pdf

16:00 The New Calibration System for Magnetic Field Probes at the LNF-INFN Magnetic Measurement Laboratory

Accurate calibration of NMR probes is essential for high-quality magnetic-field measurements. Within the PNRR IRIS project, the Magnetic Measurement Facility (MMF) at LNF-INFN has implemented a new dedicated calibration system designed and manufactured by CAYLAR. The setup includes a 2.23 T dipole magnet with a 35 mm gap, a 1ppm four-quadrant power supply for low-field operation, and three NMR probes with associated electronics, covering the 200 G to 2.2 T range. The probes are mounted on a dedicated holder positioned in a highly uniform field region, ensuring that all sensors experience the same magnetic environment. Achieving excellent homogeneity over a large volume and wide field range was a key challenge; this was addressed through a genetic-algorithm-optimized magnet design complemented by active shimming coils. This contribution presents the system’s design, construction, and factory acceptance tests, along with the first calibration results obtained at MMF. Future improvements include thermostating the probe holder, potentially using cryogenic liquids, to extend the temperature range for calibrations, an important capability for probes used in superconducting magnets.

Speaker: Antonio Trigilio (Istituto Nazionale di Fisica Nucleare)

MOP7063_edited_version.pdf

16:00 The potential of multi-material additive manufacturing illustrated by an RFQ prototype

A variety of studies show that additive manufacturing (AM) of particle-accelerator components using laser powder bed fusion (PBF-LB/M) offers significant potential to reduce investment costs while simultaneously improving figures of merit. However, the classical PBF-LB/M process does not support combining different materials within a single piece. Conventional manufacturing routines are therefore still required, for example, to join steel flanges with knife-edge sealing interfaces to copper cavities. A novel multi-material (MM) PBF-LB/M process now enables the fabrication of high-quality (e.g., high-density) geometries by combining different materials such as Cu, CuCr1Zr, Ta, W, aluminum alloys, or stainless steel. Highly functional parts tailored to the diverse requirements of accelerator components can now be additively manufactured within a single process step. To demonstrate this potential for the first time, we fabricated a monolithic RFQ prototype from two different materials using MM PBF-LB/M. The RFQ’s inner cavity is manufactured from CuCr1Zr, enabling a complex, near-surface cooling system, while the co-printed outer shell is made of tool steel to integrate two CF63 and four CF16 flanges. The inner cavity surface was electropolished and subsequently copper plated to increase the quality factor. Low-level RF measurements match the performance predicted by CST simulations. The Helium leak rate is equivalent to those of conventionally manufactured RFQ cavities.

Speaker: Michael Mayerhofer (Universität der Bundeswehr München)

MOV7004_edited_version.pdf

16:00 The SOLEIL II magnets

The SOLEIL II upgrade relies on a lattice combining 7BA
and 4BA High-Order Achromat (HOA) cells. Strict compact-
ness constraints and energy efficiency objectives have driven
the adoption of permanent magnet based technology for
the main bending and focusing elements, while quadrupole
correctors, sextupoles, and octupoles remain resistive to pre-
serve operational flexibility. This paper presents the latest
progress in the design, optimization, and prototyping of the
SOLEIL II magnet system.

Speaker: Abderraouf OUAZIB (Synchrotron soleil)

MOP7059_edited_version.pdf

16:00 The SUNDAE2 Measurement System at European XFEL

EUXFEL is preparing a combined Hall probe, moving and pulsed wire measuring system (SUNDAE2), which conceptual design has been presented already before. Now the hardware realization with functional tests can be reported. The challenge is to operate these systems under vacuum to magnetically characterize S-PRESSO (Superconducting undulator PRE-SerieS mOdule), in construction at Bilfinger and planned to be installed at European XFEL.

Speaker: Thomas Schmidt (European X-Ray Free-Electron Laser)

MOP7122_edited_version.pdf

MOP7122_edited_version.pdf

16:00 The superconducting magnets for FAIR - overview and project status

Superconducting magnets are widely used in the FAIR facility in Darmstadt, Germany. For the main accelerator, the heavy-ion synchrotron SIS100, the iron dominated superconducting magnets are fast ramped, with up to 4 T/s for the dipole magnet. The ion-optical elements of Super-FRS are realized by large aperture superconducting magnets mostly.
The large aperture dipole magnet will be installed a cave for Compressed Baryonic Matter (CBM) experiments. These magnets have a coil wound with low temperature superconductor (LTS, namely Niobium-Titanium), are cooled down to 4 K.

For SIS100, installation and interconnection of the dipole magnets in the accelerator ring tunnel have been already started. Complex supply chain from the production to the assembled module testing of the quadrupole magnets with corrector magnets and beam instrumentations were reinforced. The first three Super-FRS multiplets at the pre-target area have been installed into the FAIR tunnel and connected to the local cryogenic system. For enabling FAIR's first scientific objective, so called Early Science, a comprehensive review workshop on Super-FRS's superconducting magnets was held. Production of the large aperture dipole magnet for CBM is ongoing at German industry.

From the production, acceptance tests of the magnets and magnet modules, to the installation and the commissioning strategy of these magnets will be presented.

Speaker: Kei Sugita (GSI Helmholtz Centre for Heavy Ion Research)

16:00 THz-driven deflection of ultrashort electron bunch

Accurate characterization of longitudinal properties in ultrashort electron bunches constitutes a fundamental prerequisite for advancing scientific applications of compact particle accelerators. Here, we present an on-chip integrated terahertz (THz)-driven dielectric particle deflector based on the inverse Cherenkov effect: by coherently illuminating a high-breakdown-threshold right-angle prism with two linearly polarized lasers featuring a 180° phase difference, synchronized evanescent waves are excited on the prism’s hypotenuse surface, enabling phase matching between particle velocity and wave velocity to generate sustained transverse deflection forces. This method successfully reconciles the inherent constraints of optical laser bunch length and radiofrequency input power, while achieving scalable temporal resolution from 10 femtoseconds to the attosecond regime. Simulation results validate that the proposed scheme provides a robust technical platform for on-chip longitudinal bunch diagnostics and particle manipulation, holding significant application prospects in electron bunch-based scientific facilities.

Speaker: Chengzhe Wang (National Synchrotron Radiation Laboratory, University of Science and Technology of China)

MOP6644_edited_version.pdf

16:00 Towards a Low Impedance Vacuum System for the FCC-ee

The design of the Future electron--positron Circular Collider (FCC-ee) vacuum system integrates vacuum engineering, impedance mitigation, and surface functionalisation to achieve compatibility with high beam currents and sustained operational stability. Based on these design principles, this contribution presents an overview of the principal vacuum components and outlines the studies conducted to evaluate and optimise their electromagnetic and vacuum performance. Particular emphasis is placed on the interplay between material properties, surface treatments, and component geometry, as well as on the distribution and integration of vacuum elements and transitions within the accelerator. Impedance studies were performed to evaluate the electromagnetic impact of representative vacuum components. The main findings are summarised, highlighting the achieved performance and outlining directions for further optimisation.

Speaker: Patrick Krkotic (European Organization for Nuclear Research)

MOP7111_edited_version.pdf

16:00 Towards laser roughening of inner beam screen surfaces for electron cloud mitigation in standalone magnets around IP1 and IP5 of the LHC

Laser-induced surface roughening facilitates secondary electron yield reduction of materials [1]. The lab-based demonstration on small scale in 2014 motivated an initiative to scale-up the technology for processing of long vacuum components with inner surfaces to be treated in apertures < 50 mm, which is challenging. To address this, we have developed a technique that enables the selective transformation of the inner beam screen (BS) surfaces in LHC standalone magnets for electron cloud mitigation [2]. This requires scanning the light generated by a pulsed laser across the surface of ~10 m long BSs. The developed system consists of an IR laser and a 17 m long optical fiber that transmits the light to an inchworm mole, which houses an optical focusing unit and allows to scan the laser spot. We will present our solutions to the emerged challenges: i) mitigate surface oxidation, ii) avoid the contamination of cryosorbers, iii) integrate a synchronized fiber management system, iv) assure an acceptable treatment speed, v) find a compromise to match all material requirements, vi) extract ablated particulates, vii) monitor the process for quality control, and viii) perform a post-processing cleaning. By combining these steps, the influence on the beam impedance was minimized, and the compatibility with LHC operation was demonstrated.
[1] R. Valizadeh et al, Appl. Phys. Lett. 105 (2014), 231605.
[2] Elena Bez et al., RSC Appl. Interfaces 2 (2025), 521.

Speaker: Dr Marcel Himmerlich (European Organization for Nuclear Research)

16:00 Transient Electromagnetic Modeling of No-Insulation HTS Coils Using a MEMEP-Based Lumped-Circuit Framework

High-temperature superconducting (HTS) magnets are increasingly considered for compact, high-field accelerator applications due to their large current capacity, thermal stability, and reduced cryogenic requirements. No-insulation (NI) HTS coils further provide compact winding and intrinsic self-protection, but their transient current redistribution during ramping or local quench can introduce dynamic electromagnetic behavior that must be accurately captured for reliable magnet operation.
This work presents a modeling framework to predict the transient electromagnetic behavior of NI coils for HTS accelerator and magnet applications. The method combines a lumped circuit model with a Minimum Electromagnetic Entropy Production (MEMEP) formulation to obtain physically consistent current evolution constrained by coil topology. The approach captures resistive current sharing and inductive dynamics without requiring full 3D finite element modeling (FEM) at each step. Benchmarking against FEM simulations confirms its ability to reproduce NI transient electromagnetic behavior. This work provides a practical tool to integrate NI coil physics into superconducting magnet design and analysis.

Speaker: Dr Lorenzo BORTOT (European Synchrotron Radiation Facility)

16:00 Tuning Strategies for the FCC-ee Local Chromaticity Correction Collider Lattice

The Future Circular Collider – electron-positron (FCC-ee) aims to deliver ultra-low emittance beams to enable precision measurements across multiple energy regimes. Achieving and maintaining optimal machine performance requires robust tuning methods capable of correcting a wide range of imperfections. In this contribution, we evaluate the impact of realistic misalignment errors and magnet multipole field imperfections on the Local Chromaticity Correction (LCC) collider lattice design and assess the effectiveness of state-of-the-art correction strategies inspired by modern light sources.

Speaker: Kévin André (European Organization for Nuclear Research)

16:00 Ultra-low beta* optics proposal with new final doublet and better field quality at ATF2

The ultra-low 𝛽𝑦* optics at the Accelerator Test Facility 2 (ATF2) enables studies of final focus systems under chromatic conditions relevant for future linear colliders. Following the installation of a new final doublet with improved field quality, the achievable beam size and the contribution of nonlinear aberrations are re-evaluated. Using high-order tracking with MAD-NG, the vertical beam size is decomposed into second-and third-order contributions, allowing a quantitative assessment of correction schemes based on sextupole and octupole magnets. In addition, recent emittance measurements provide realistic beam conditions for these studies. Strategies to enhance the experimental observability of octupole corrections are discussed

Speaker: Lewis Kennedy (European Organization for Nuclear Research)

16:00 Uncertainty analysis of time constant measurements in SRF cavity testing

At the start of superconducting radiofrequency cavity testing, cavity time constant measurements are taken and from these measurements the field probe external quality factor is calculated. This value is then used for the calculation of quality factor and accelerating gradient for the remainder of the testing process. In previous analyses the uncertainty of the time constant measurement has been given as 3%, but this is dependent on the measurement equipment and method used to estimate the time constant from the measured cavity decay curve. This paper presents an analysis of the uncertainty of the measurement equipment used in the Superconducting Radiofrequency Laboratory at STFC’s Daresbury Laboratory and a comparison of the different methods that can be used to estimate the time constant from a decay curve.

Speaker: Matthew Jones (ASTeC, STFC Daresbury Laboratory)

MOP7048_edited_version.pdf

16:00 Unifying efforts in electrical safety for an accelerator complex

Large research facilities with continuously evolving electrical installations and many stakeholders often face unique challenges in implementing electrical safety. The Electrical Safety Project at CERN aims to standardize methods and processes in order to improve electrical risk management during maintenance and operation of the CERN accelerator complex. The project focuses on several axes for improvement. Two of these are the clear identification of the limits of responsibility along the powering supply chain among different teams that provide equipment for accelerators, and the reconstruction of the electrical dependencies between equipment from the source to the load. After introducing the project with its challenges, the paper will report on the progress made by ESP in these two specific fields and on the proposed methodology towards their long-term implementation.

Speaker: Cornelia Marion Schmitt (European Organization for Nuclear Research)

MOP7146_edited_version.pdf

16:00 Update on injection optics into the Electron Ion Collider Hadron Storage Ring

The Electron Ion Collider Hadron Storage Ring (HSR) will be built on the campus of Brookhaven National Laboratory. The injection into the HSR will be vastly different from what is currently performed in the Relativistic Heavy Ion Collider. This paper will highlight the differences from RHIC, present the injection optics, and layout of the current design.

Speakers: Chuyu Liu (Brookhaven National Laboratory), Vincent Schoefer (Brookhaven National Laboratory)

MOP1303_edited_version.pdf

16:00 Updated RF Design and Optimization of 3 GHz Traveling-Wave Structures for the FCC-ee High-Energy Linac

The high-energy (HE) linac for the FCC-ee injector complex must deliver 20 GeV beams with high stability for top-up injection. Following an initial design at 2.8 GHz, the RF frequency has been updated to 3 GHz to align with the European S-band standard, enhancing compatibility with existing high-power RF components and industrial manufacturing for the Technical Design Report (TDR) phase.

This paper presents the updated design of 3 m traveling-wave (TW) accelerating structures operating at 3 GHz. A parametric optimization of the full structure geometry is performed, balancing effective shunt impedance and peak surface fields. Beam-loading compensation is applied via optimized RF pulse shaping for various bunch spacings. Detailed wakefield studies are conducted for various bunch spacings to ensure the transverse wake potential remains below the stringent 0.2 V/pC/mm/m threshold. Finally, tolerance studies quantify the sensitivity of wakefield suppression to manufacturing errors, establishing practical fabrication limits for the 3 GHz structures.

Speaker: Adnan Kurtulus (European Organization for Nuclear Research)

MOP7013_edited_version.pdf

16:00 Updates on impedance studies for the FCCee high energy booster

Following the Future Circular Collider (FCC) Feasibility Study completion, the impedance model for the FCC-ee High-Energy Booster (HEB) has been significantly expanded beyond the initial copper vacuum pipe resistive wall analysis. This paper presents a comprehensive impedance and wake budget incorporating RF cavities, bellows, and beam position monitors, evaluated through 3D electromagnetic simulations and analytical methods.

The updated model provides the basis for future beam dynamics studies, including transverse coupled bunch instability analyses and single bunch tracking simulations. The present work focuses on the construction and comparison of the main impedance and wake contributions, identifying the dominant sources and the components requiring further investigation. These results will be used to refine the HEB collective effects studies and to support future assessments of instability margins and mitigation requirements.

Speaker: Keon Hee Kim (Grand Accélérateur National d'Ions Lourds)

MOP1072_edited_version.pdf

16:00 Updates on the sustainability improvements of the Karlsruhe Research Accelerator

The thermal well system to support the cooling plant of the accelerator test facility Karlsruhe Research Accelerator (KARA) at the Karlsruhe Institute of Technology (KIT) is in test operation after about one year of commissioning. To avoid any impact on the environment, follow the governmental regulations, and document different aspects and operation statistics, KIT developed a special robust and reliable data handling pipeline.

We describe the implementation of the data archiving strategy, as well as the experiences gained and statistics on e.g. power reduction from the first year of commissioning of the thermal wells. Furthermore, our plans for improvement and extension of KARA's efforts towards sustainable operation are presented.

Speaker: Julian Gethmann (Karlsruhe Institute of Technology)

MOP7143_edited_version.pdf

16:00 Upgrade of the arcing suppression system for the waveguides in the European XFEL

When planning the European XFEL, the decision was made to avoid using SF6 in the waveguide systems. Instead, air was used at slight to high overpressure. When slight overpressure is used, the air is also in motion. The air flow travels from the RF source towards the cavities and is released again before the coupler. This ensures that, in our non-gas-tight waveguide system, the air quality in the waveguides corresponds to the air quality supplied by the compressor. Particles and ionised air that could promote arcing are blown out. Originally, the air pressure was generated by local compressors and the air used came from the ambient atmosphere. Now, the accelerator’s central compressed air system is utilised. Locally, only the newly developed controls for air pressure and flow remain. The advantage of the central compressed air supply lies in the significantly better air quality and greater operational reliability.

Speaker: Michael Bousonville (Deutsches Elektronen-Synchrotron DESY)

MOP7001_edited_version.pdf

16:00 Upgrade of the SPS Target External Dump for high intensity operation in CERN’s North Area

As part of the consolidation of CERN’s North Experi-mental Area (NA-CONS project), a dump located in the TT20 transfer line has been redesigned to comply with the higher beam intensities required for the future BDF/SHiP facility, and to improve its operational relia-bility. The new dump must be capable of dissipating up to 45 kW of steady-state power generated by the slow extraction of 400 GeV/c protons from the SPS under vari-ous operational scenarios. In addition, it shall also be able to withstand short, high-intensity pulses during machine development phases. Building upon proven design concepts implemented in the previous generation of SPS dumps [1,2], the dump core consists of graphite blocks clamped by actively cooled CuCr1Zr plates, and is enclosed by two shielding layers, steel and marble, for radiological protection. The design has been validated by performing beam-matter and thermo-mechanical simu-lations. A dedicated testbench was used to estimate the thermal contact conductance between materials and pro-vide realistic values for the simulations. This contribu-tion presents the main stages of this upgrade, from defini-tion of updated beam parameters to conceptual design and validation.

Speaker: Thibaut Parmentier (European Organization for Nuclear Research)

MOP7136_edited_version.pdf

16:00 Use of DBSCAN for full-automatic-data-based anomaly detection method on Turn-by-Turn Beam Position Monitors (TbTBPMs) in SuperKEKB

In order to consistently operate collider at peak luminosity, one have to know in detail the full magnetic lattice of the colliding rings, and to know in particular the deviation of the real lattice from the model used in the design phase.
Turn-by-turn BPMs surveys are one of the method available to measure this deviation. Based on the n-BPM method developped at CERN, the spectral response of the TbTBPMs all around the rings allow for the reconstruction of the full effective magnetic lattice.
However, the measurement is very dependant on the status and precision of each TbTBPM in the ring.
A method to automatically detect and eliminate problematic BPMs from magnetic lattice reconstruction scripts is presented. It is based on a library called Time2Feat to extract and select automatically the most dissociative features from the TbTBPMs time-measurements, and the Density Based Spectral Clustering Application with Noise (DBSCAN) algorithm to detect potential outliers from a clustering of the BPMs inside the hyperspace of the computed features.
The main asset of this method is its light weight since very little training is needed, the possibility to detect outliers from very scarse measurements as input (the very problematic BPMs are detected with only one measurement from each BPM), and a data-based selection of features, preventing the introduction of any bias and allowing for the best feature-set selection possible for each measurement.

Speaker: Quentin Bruant (Commissariat à l'Énergie Atomique et aux Énergies Alternatives)

MOP1032_edited_version.pdf

16:00 Using Machine Learning in Control System for Isochronous Cyclotron

Crocker Nuclear Laboratory has been going through a modernization in its control system. One of the projects being made for the modernization is using machine learning to model the isochronous cyclotron environment & to use that model for autonomous control. The model uses convoluted neural networks, and uses 32 controlled parameters that all affect the beam current and stability. This model is then used in a reinforcement learning model that will be used for autonomous control, which serves as a piece on the new digital control system that is currently being implemented. The system will focus on controlling the trim coil magnets to maintain a stable beam. The goal is to unravel new/simple tunings for a continuous spectrum of energies of the machine.

Speaker: Gabriel Soto (University of California, Davis)

16:00 Vacuum design and pressure modelling of the AWAKE Run 2c beamlines

AWAKE is the proton-driven plasma-wakefield acceleration experiment at CERN, currently preparing a major upgrade for Run-2c, scheduled to start in 2029. This phase will introduce new beamlines and extended infrastructure, including separate proton bunches-modulation and electron-acceleration stages, achieved in two plasma cells. These planned additions impose complex integration constraints across the facility.
This contribution presents the updated vacuum layout - and its associated remote-control system - and addresses the integration challenges of multiple coexisting systems under vacuum, including the proton and diagnostic beamlines, two electron beamlines with their respective RF e-guns and RF waveguides, IR and UV laser transport lines. Each system features different pressure requirements and dedicated pumping strategies.
Tailored pumping schemes were defined based on expected gas loads, operating scenarios and the limited space available. Analytical conductance and pressure calculations were performed to estimate baseline performance, while Molflow+ simulations were carried out for selected beamlines to characterize pressure profiles and validate the proposed pumping configuration. The contribution summarizes the vacuum-related challenges identified during the design and preparation for Run-2c and provides an overview for the upcoming installation phase.

Speaker: Maria Carmen Giordano (European Organization for Nuclear Research)

MOP7099_edited_version.pdf

16:00 Vacuum Facility at LNF-INFN for Present and Future Accelerators

A thorough understanding of material properties in vacuum, including cleanliness and storage conditions, is critical for ensuring the longevity of accelerator vacuum systems. Originally established for the design, testing, and installation of components for projects like Adone, DAΦNE, and SPARC, the LNF-INFN vacuum laboratory has evolved into a strategic infrastructure supporting current and future flagship projects, including TEX, EuPRAXIA, FCC, ET and EIC. The facility features an ultra-high vacuum (UHV) component preparation and cleaning room with large ultrasonic tanks, a vacuum brazing furnace (10⁻⁶ mbar, up to 1200°C), a heat-treatment furnace (up to 450°C), and an outgassing characterization system. In collaboration with MaSSLab at DAΦNE-L, it also provides surface characterization capabilities, including XPS and Secondary Electron Yield (SEY) measurements at both room and cryogenic temperatures. This work presents each system's technical specifications alongside relevant application case studies.

Speaker: Luisa Spallino (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati)

16:00 Vacuum simulations for HL-LHC Long Straight Sections

The High Luminosity Large Hadron Collider (HL-LHC) is entering its final development phase, requiring the optimisation of its vacuum layout to ensure reliable operation. The main upgrades with respect to the current LHC involve the Long Straight Sections next to the two large, general-purpose experiments (ATLAS and CMS), including new final focusing magnets and a full crab crossing implementation using superconducting crab cavities. Since residual gas critically affects collider performance, extensive vacuum simulations have been conducted to evaluate and minimise pressure levels. These include steady-state studies accounting for phenomena like photon, electron and ion-induced desorption, to determine pressure. The simulations employ several complementary tools: Molflow+ for Monte Carlo particle tracking in ultra-high vacuum conditions, Synrad+ for synchrotron radiation effects, and the MATLAB-based VASCO code for pressure stability analysis.

Speaker: Alessio Galloro (European Organization for Nuclear Research)

MOP7100_edited_version.pdf

16:00 Vacuum tolerance limits for LSS7: balancing performance and radiation exposure

The High Luminosity LHC project requires a flexible approach to collimator vacuum conditioning that addresses both operational vacuum performance and the maintenance constraints associated with highly radioactive equipment. This work combines outgassing studies and LHC pressure profile analyses to optimize the vacuum conditioning procedure for collimators used for betatron cleaning installed in the Long Straight Section of Point 7 (LSS7) of the LHC. The proposed approach simplifies the bake-out procedure aligning with As Low As Reasonably Achievable (ALARA) principles, reducing intervention complexity and personnel radiation exposure without compromising vacuum quality. This study was supported by the HL-LHC project.

Speaker: Marios Kyprianidis (European Organization for Nuclear Research)

MOP7108_edited_version.pdf

16:00 Validation of the new HL-LHC baseline and alternative operational scenarios

The High Luminosity (HL–LHC) project aims to increase the integrated luminosity of CERN’s Large Hadron Collider (LHC) up to 3 ab−1, and 4 ab−1, as Nominal and Ultimate goals, respectively, over the full lifetime of the facility. The large boost in bunch population and beam brightness, compared to the currently achieved beam parameters in the LHC and stemming from the LHC injector upgrade project deployed during the previous long shutdown 2, poses several beam dynamics challenges that must be addressed, including, for example, electron cloud, impedance-related stability, and beam lifetime. In addition, the increasing availability of measurements for the magnets to be installed in the ATLAS and CMS interaction regions also allows for a more precise determination and optimisation of the dynamic aperture. Recently, modifications of the HL–LHC operations baseline, including ion runs throughout the lifetime of the project, led to a tighter margin on the integrated luminosity goals. Therefore, we present here an update of the baseline scenario of HL–LHC, together with alternative proposals that could mitigate potential shortcomings.

Speaker: Nicolas Mounet (European Organization for Nuclear Research)

MOP1011_edited_version.pdf

16:00 Vertical deformation of the 10 TeV muon collider ring for neutrino flux mitigation

Muons offer several advantages for circular colliders: as leptons, they allow for high-precision and similar physics reach as larger hadron colliders, while their higher mass suppresses the synchrotron radiation that limits circular electron colliders. The main challenge of muon colliders is the short lifetime of muons. Muon decay generates an intense neutrino flux emitted in a narrow cone tangential to the beam trajectory. To keep the resulting radiation at the Earth’s surface negligible, dedicated mitigation strategies are required. Besides minimizing straight sections, the main mitigation measure under consideration is to periodically deform the beam trajectory and collider ring vertically to spread the neutrino flux over a larger area. This can be achieved by installing all ring magnets on a mechanical system allowing to move them regularly and adding horizontal magnetic field components. However, this affects the collider optics, especially since it introduces vertical dispersion that must be properly matched across the lattice. The present work presents the first studies on the impact of such vertical periodic deformation on beam dynamics and collider performance.

Speaker: Marion Vanwelde (European Organization for Nuclear Research)

MOP1045_edited_version.pdf

16:00 Vertical testing of the Waveguide-HOM-Damped 1.5 GHz 4-Cell prototype cavities for the VSR-Demo project

The VSR Demo project aims for the validation of a cavity design suitable for the application in electron storage rings, characterized by currents of several hundreds of mA and a dense wakefield spectrum caused by inhomogeneous fill patterns. The cavities are equipped with five waveguides plus a coaxial fundamental power coupler, forming two groups of three radial extensions at either cavity end. Recently two prototypes were manufactured and are in the process of vertical testing at HZB’s Large Vertical Test Stand. First tests completed with Prototype 1, covering all modes of the fundamental passband and different temperature levels, did not match the Q(E)-performance expectations, but indicate a yet unknown loss mechanism in the cavity’s periphery, i.e. waveguide endgroups, beam pipe extensions, blind flanges or the coupling feedthrough. Further insights are expected from the ongoing testing program with modified coupling and with Prototype 2.

Speaker: Hans-Walter Glock (Helmholtz-Zentrum Berlin für Materialien und Energie)

MOP7024_edited_version.pdf

16:00 Waveform pattern control of the paint bump power supply for the J-PARC RCS using neural networks

The J-PARC RCS uses four horizontal and two vertical painting magnets to generate a high-intensity beam through painting injection. Their IGBT-chopper power supplies can reproduce current waveforms with an accuracy of better than 1%. Combining automatic generation of input voltage (IV) patterns with manual fine-tuning keeps the current deviation of the painting pattern (PP) within ±0.2%.
There are 90 waveform patterns in total, including two types: trapezoidal patterns for low-beam-loss studies and painting patterns for high-intensity beam production. As these patterns have different current demands and impose different loads on the power supplies, the tuning process becomes increasingly complex. Adjusting one PP takes approximately one hour and optimising all 90 patterns takes several days; therefore, reducing the adjustment time is essential.
To address this issue, a neural-network (NN) approach was applied to generate optimized IV patterns. Training the NN with existing IV data yielded highly accurate voltage patterns, improving PP reproducibility. This presentation reports on NN-based waveform optimisation and its application to beam operation.

Speaker: Moe Sugita (Japan Atomic Energy Agency)

MOP6612_edited_version.pdf

16:00 X band Linac machine design for very high energy electron therapy

Very high energy electrons (VHEE) are a potential future modality in the field of radiotherapy. They have garnered considerable interest because they possess a unique combination of several properties including: being capable of deep tissue penetration (>30 cm), relative insensitivity to tissue inhomogeneities and being well suited to FLASH therapy. FLASH is the use of ultra-high dose rates which have been shown to reduce cell death in healthy tissue whilst maintaining toxicity to tumours. Recent studies indicate that higher energy beams produce less scattering and more precise dose delivery up to at least 250 MeV. This paper provides a design for a 250 MeV linac with dose rates exceeding 100 Gy/s in a 10 cm × 10 cm wide field size. The design is centred on a bi-periodic, π/2 mode, normal conducting, standing wave, accelerating cavity which emphasises stability. A gradient of 100 MV/m has been chosen to achieve the compactness potentially required to fit the accelerator in a hospital setting. To this end, 11.9942 GHz X-band technology has been selected which, along with extensive cell geometry optimisation, has produced a shunt impedance of > 95 MΩ/m and whilst minimising surface electric and magnetic fields.

Speaker: Euan Smith (University of Manchester, Cockcroft Institute)

MOP7018_edited_version.pdf

16:00 XBPM calibration and simulations at SIRIUS

The set of X-ray Beam Position Monitors (XBPMs) at SIRIUS, the Brazilian Synchrotron Light Laboratory (LNLS), is not yet fully operational due to ongoing calibration challenges. These SIRIUS XBPMs employ a blade-type design, which exhibits a linear response only in its central region. Minor asymmetries in device construction and variations in individual blade gains can amplify distortions in the calculated beam position derived from the photocurrents generated by X-ray incidence.

Standard correction methods involve applying a linear transformation to the signals, calibrated by analyzing blade behavior along central-symmetry lines. To enhance accuracy, we have extended these corrections by optimizing the transformation matrix using a simulated annealing algorithm. Furthermore, to deepen our understanding of the relationship between incident X-ray distribution and blade geometry, we developed a simulation algorithm. This tool models the blades' response to radiation, calculating the apparent beam position for various configurations of blade angles, inter-blade distances, and electronic gains. The simulation accepts a range of input beam profiles—including two-dimensional Gaussian distributions or outputs from radiation transport simulators—and can apply transformations such as stretching and rotation to these profiles.

Speaker: Gabriel Ascenção (Brazilian Synchrotron Light Laboratory)

MOP6344_edited_version.pdf

Tuesday 19 May

09:00 → 10:30 MC2 : Photon Sources and Electron Accelerators

09:00 Commissioning and current status of High Energy Photon Source (HEPS)

The first 4th generation light source in China, HEPS, has been constructed and commissioned. The new light source is expected to produce the emittance of less than 100 pm.rad that can provide hard X-rays with the brilliance higher than 10^22 photons/sec/mm^2/mrad^2/0.1%B.W. In order to stably operate this ultra-low emittance ring, HEPS accommodated the advanced swap-out beam injection scheme, in which the kicked-out beams return to the booster synchrotron for reuse. This talk will present the current status of accelerator and beamline commissioning and future plan.

Speaker: Yuhui Dong (Chinese Academy of Sciences)

TUI2M02_talk.pdf

TUI2M02_talk.pptx

09:30 SOLEIL II: The French 4GLS project - first year of the construction program

SOLEIL II [1] is the French upgrade project of SOLEIL delivering next-generation synchrotron light source through a full renewal of the accelerator complex, the upgrade of 29 beamlines and three laboratories, and a major IT transformation. The compact 2.75 GeV, 354 m Storage Ring will reach 50 pm round-beam emittance using an atypical 7BA–4BA lattice, extensive use of permanent-magnet technologies, nearly 100% NEG coating, 12 mm diameter vacuum chambers, a new in-vacuum nonlinear kicker for transparent top-up operation, new 4th-harmonic cavities, and 10 µm magnet alignment. The new 5 nm emittance Booster adopts a 14-HOA lattice. Both lattices are frozen, enabling construction. SOLEIL II will provide a 100-fold coherent-flux gain, a nine-decade energy range, nanoscale resolution, and fully multimodal in-operando capability. This contribution highlights how the prototype phase builds confidence in these targets, with progress in accelerator technology, in collimation, risk mitigation, and major prototypes. Building upgrades have started, and the first major equipment tenders are being launched. The project optimizes cost and ensures environmental compliance, targeting 50% electricity savings. Commissioning is expected in early 2030.

Speaker: Laurent Nadolski (Synchrotron soleil)

09:50 EuPRAXIA at ELI ERIC: development of a compact LPA FEL and plasma sources for ultrafast science

The ELI Beamlines Centre, situated near Prague in the Czech Republic and operating as part of ELI ERIC, has been designated as the second pillar of the EuPRAXIA distributed user facility. It is developing a user-focused programme centred on laser–plasma accelerators (LPAs). A key initiative involves creating an LPA-driven free-electron laser (FEL) for the XUV and soft X-ray water-window ranges. The soft X-ray line will operate with approximately 1 GeV LPA electrons at 100 Hz, supporting research in biology, ultrafast chemistry, and nanoscale materials. The XUV line enables a broad scientific programme including time-resolved spectroscopy, attosecond dynamics, ultrafast magnetism, and surface science.
The project utilises unique features of LPA-based FELs compared to LINAC-based facilities: naturally few-femtosecond electron bunches, high peak currents without needing compression, inherent sub-femtosecond synchronization with the drive laser, and a significantly smaller accelerator footprint. These features enable experimental regimes that are challenging for existing large-scale FELs, particularly in ultrafast pump–probe and attoscience applications.
Complementary developments include betatron X-rays and a low-energy positron source from a kHz LPA accelerator, broadening user access to advanced plasma-driven radiation and particle beams within the EuPRAXIA framework.

Speaker: Dr Alexander Molodozhentsev (Extreme Light Infrastructure Beamlines)

TUO2M02_edited_version.pdf

TUO2M02_talk_edited_version.pdf

10:10 Development Progress of the SHINE Accelerator

The SHINE is a high repetition-rate X-ray FEL facility, based on an 8-GeV CW superconducting RF linac, which will become one of the most powerful photon srouces in the world. This project is initiated in 2018 and is under construction up to now. It has been designed to build an 8 GeV CW SCRF linac at repetition rate as high as 1 MHz, 2 beamlines to deliver photons between 0.2 and 15 keV and 6 experimental stations. The construction and commissioning of the injector and L1/BC1 section has already finished in 2024 and 2025 respectively. The progress of the SHINE accelerator will be presented.

Speaker: Bo Liu (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

TUO2M03_talk_edited_version.pdf

09:00 → 10:30 MC8 : Applications of Accelerators, Engagement with Industry, Technology Transfer and Outreach

09:00 Particle accelerator-driven muon spectroscopy: an invaluable tool to understand our material world.

Muons are generated at several accelerator-based facilities around the world and can be implanted into a wide range of materials, acting as a local probe of the surrounding atomic environment. By measuring the muon’s precession and relaxation can provide an understanding of the material of interest and, from this, unique information is obtained on the static and dynamic properties. This has enabled muon spectroscopy to develop into a powerful tool to investigate materials, such as fundamental magnetism, superconductivity and functional materials, energy storage, ionic diffusion in potential batteries, the dynamics of soft matter, free radical chemistry, reaction kinetics, semiconductors, advanced manufacturing, cultural heritage, and even the effects of muons on electronics*. This talk will introduce the techniques, give an overview of the global facilities, describe the important characteristics of the particle accelerator, and highlight some recent scientific highlights.

Speaker: Adrian Hillier (Science and Technology Facilities Council)

TUI8T01_talk_edited_version.pdf

09:30 First mixed He/C ion beams at a clinical facility: two years from concept to first ion imaging experiments

Patient irradiation with mixed 4He2+ and 12C6+ ion beams is a promising proposal for online monitoring in carbon ion therapy. Over the past years, major developments have enabled the generation of such beams at MedAustron, where they are now used in accelerator, detector, and medical physics research projects.

This contribution summarizes the key innovations that made this achievement possible. Among these are a new double multiturn injection scheme for merging helium and carbon ion beams in the synchrotron, concepts for simultaneous slow extraction of both ion species, and dedicated diagnostic tools for mixed beam characterization in the accelerator and experimental room. Together, these advances pave the way for continued progress in the field of mixed ion beam acceleration and application.

Speaker: Elisabeth Renner (TU Wien)

TUO8T01_edited_version.pdf

TUO8T01_talk_edited_version.pdf

09:50 Accelerators activities at ENEA for aerospace

The ENEA Frascati Particle Accelerator Laboratory operates a set of S-band electron and proton linear accelerators providing beams relevant for radiation-effects studies in the aerospace sector. The TOP-IMPLART proton LINAC delivers low-energy (1–6 MeV) and high-energy (up to 71 MeV) beams, while the REX and TECHEA facilities supply 3.5–5 MeV and 1–3 MeV electron beams, respectively; both can also operate as X-ray sources via removable bremsstrahlung converters.
The contribution reviews ENEA activities in aerospace applications, including irradiation of electronic components, material and shielding studies, and radiobiology and astrobiology experiments. ENEA is involved in several national and European projects— such as Cyptomars, Space It Up!, Space-EBC, and Thread — addressing key topics for space exploration. In parallel, ENEA provides irradiation services within infrastructures such as DIANA and ASIF supporting component testing and material qualification.
This work highlights ENEA’s role in supporting the aerospace community through advanced accelerator capabilities, coordinated research initiatives, and a broad portfolio of irradiation services aimed at enhancing the robustness and space-readiness of technologies for future missions.

Speaker: Giulia Bazzano (ENEA Frascati Research Centre)

TUO8T02_edited_version.pdf

10:10 Mapping Global Collaboration in Accelerator Research

This contribution examines particle accelerator research through a sociological lens. It combines a database of accelerator counts per country with a large corpus of accelerator-related publications from Web of Science to analyse how infrastructure distribution shapes scientific collaboration across regions and disciplines. The results reveal marked geographical asymmetries: some regions sustain dense internal publication networks while others participate primarily through cross-regional partnerships. The analysis also identifies clear disciplinary differences in how fields such as astronomy, materials science, and chemistry mobilise accelerator infrastructure through distinct collaboration configurations. Together, these patterns illustrate how scientific collaboration crystallises around shared infrastructures, how expertise circulates unevenly between regions, and how accelerators support the emergence of differentiated epistemic communities. The study offers an empirical perspective on the social dynamics underpinning global accelerator research and raises questions for future qualitative and longitudinal investigation.

Speaker: Annabella Zamora (University of Lausanne)

TUV8002_edited_version.pdf

10:30 → 11:00 Coffee break

11:00 → 12:00 MC3 : Advanced acceleration techniques and novel particle sources

11:00 High quality electron beams with tunable energy produced by laser-plasma acceleration

Laser wakefield acceleration (LWFA) of electrons occurs when an intense short laser pulse focused in an underdense plasma drives in its wake a plasma wave with an amplitude large enough to trap and accelerate electrons. Relativistic electron bunches are easily obtained through this mechanism and have given rise to a large number of studies and publications. Despite these efforts, the achievement of a high quality reliable electron source, ready for use in applications, still needs some developments.
Electron beams with high quality, and tunable electron energy, have been achieved by the authors using the DRACO facility (HZDR Dresden), showing that the injection and acceleration processes can be controlled consistently in a gas cell. Dark current free, relativistic electron bunches with energy peaked at tunable values between 60 MeV, and 200 MeV, 40 pC charge in the peak and sub-mrad rms divergence, reaching up to 14pC/MeV/mrad, have been achieved experimentally and reproduced in PIC simulations using measured input parameters. On going work is aimed at increasing the charge in the peak beyond 100pC through new gas cell development.

Speaker: Brigitte CROS (Laboratoire de Physique des Gaz et des Plasmas)

TUI3T01_edited_version.pdf

11:30 First direct observation of a wakefield generated with structured light

Since their inception, laser-wakefield accelerators (LWFAs) have shown their capability to produce high-quality, monoenergetic electron beams. Yet, the push toward higher electron energies and more efficient accelerators is constrained by several limitations. Foremost among these are the dephasing and diffraction limits. A promising strategy to address these issues involves using structured light to modulate the on-axis propagation velocity in LWFAs. By pairing the diffraction-resistant properties of Bessel beams with spatio-temporal pulse shaping, this approach offers an unprecedented combination of extended acceleration lengths and strong acceleration gradients.

Here we present the first experimental observation of wakefields driven by such structured beams. Spatio-temporally tailored pulses are directed through a specialized focusing mirror to form a quasi-Bessel beam, and the resulting wakefield is directly probed using femtosecond relativistic electron microscopy. Simulations corroborate the experimental data, offering novel insights into this underexplored regime. We show an experimental demonstration of the ability to modify the on-axis propagation velocity of the wakefield. We track the wakefield’s evolution throughout the focal region and examine how specific spatio-temporal manipulations influence both its structure and propagation velocity. Finally, we present the first results using such wakefields to accelerate electrons. These findings establish a foundation for harnessing structured-light-based strategies to overcome dephasing in LWFA.

[1] A. Liberman et al., “Direct Observation of a Wakefield Generated with Structured Light,” Nature Communications, Accepted. (https://arxiv.org/abs/2503.01516)
[2] A. Liberman et al., “First Electron Acceleration in a Tunable-Velocity Laser Wakefield,” under review. (https://arxiv.org/abs/2509.21098)
[3] A. Liberman et al., “Probing Flying-Focus Wakefields,” under review. (https://arxiv.org/abs/2510.16950)
[4] A. Liberman et al., "Use of spatiotemporal couplings and an axiparabola to control the velocity of peak intensity," Opt. Lett. 49, 814-817 (2024)

Speaker: Aaron Liberman (Weizmann Institute of Science)

TUI3T02_edited_version.pdf

11:00 → 12:30 MC4: Hadron Accelerators

11:00 Progress and status of high intensity heavy ion accelerator facility (HIAF) in China

HIAF is one of the next generation heavy ion accelerators under construction in China. It is composed of a superconducting ion linear accelerator, a high-energy synchrotron booster, a high-energy radioactive isotope beam line, an experimental storage ring and multiple experimental setups. Characterized by unprecedented intense ion beams from hydrogen through uranium, HIAF can produce a large variety of exotic nuclear matters not normally found on the earth and will bring researchers to the forefront of promoting the most vigorous and fascinating fields in nuclear physics. During the construction of HIAF, extensive R&D efforts have achieved a major breakthrough in fast-cycle acceleration through innovative technological solutions. Currently, most components have completed production and fabrication. The civil engineering and infrastructure have been completed. The facility has entered the installation phase. The accelerator equipment installation is 95% complete. The integrated commissioning of the power supply and magnet systems is in progress. The vacuum of BRing and SRing has reached 10^-12mbar. The first beam has been delivered by the combination of SECR and RFQ in August 2024. The Day One experiment is expected to be made by the end of 2025. The details of the HIAF status and progress will be given in this report.

Speaker: Jiancheng Yang (Institute of Modern Physics, Chinese Academy of Sciences)

Status and progress of HIAF project-Jiancheng Yang.pdf

11:30 Status and comparison of world-wide in-flight fragment separators

Generation of rare isotope beams by means of in-flight separation of nuclear fragments and fission products requires complex optical structures usually comprising multiple separator stages. Large apertur magnets providing maximum acceptance, radiation hard and superconducting are used to separate the reference isotope from the bulk of the primary and secondary heayv ion beam. The pre-separator stages are designed to dump a majority of the secondary beam in a controlled way and are therefore often a challenge for radioprotection, shielding and beam catchers. The complex optics of fragment separators makes use of energy degraders, intermediate focal- and image planes to minimie contamination of the desired isotopes. A comparison of optical designs and magnet technologies will be presented.

Speakers: Haik Simon (GSI Helmholtz Centre for Heavy Ion Research), Helmut Weick (GSI Helmholtz Centre for Heavy Ion Research), Martin Winkler (GSI Helmholtz Centre for Heavy Ion Research)

TUI4M01_edited_version.pdf

12:00 Accelerator complex evolution at Fermilab

The largest hadron accelerator facility in the US is undergoing radical changes and the undertaking of new HEP-driven neutrino research. This talk will discuss the wide-ranging projects and impacts to the accelerator community taking place at FNAL.

Speaker: Mary Convery (Fermi National Accelerator Laboratory)

TUI4M02_edited_version.pdf

TUI4M02_talk_edited_version.pdf

12:00 → 12:30 MC6 : Beam Instrumentation, operation Controls, Feedback and Operational Aspects

12:00 ML-driven automated tuning of SACLA XFEL: progress and future

Leveraging Machine Learning (ML), we aim to automate and simplify the complex tuning of the XFEL light source accelerator, SACLA, thereby delivering extreme XFEL performance tailored to experimental user needs. Since 2020, we have implemented a Bayesian Optimization (BO)-based automated tuning framework at SACLA. This enables us to meet the detailed XFEL requirements for the approximately ten independent experiments conducted weekly across three beamlines. These requirements include wavelength, intensity, spectral width, spectral shape, and the time interval and intensity ratio for two-pulse lasers. To enable more precise control of XFEL characteristics, a high-time-resolution X-band RF deflector is planned to install downstream of the undulators to acquire laser-amplification data. This robust ML platform is designed for broad applicability; it has been successfully tested for deployment at other accelerator facilities with minimal modifications. We are also expanding the ML scope toward fault prediction for various hardware components, paving the way for fully autonomous operation. This presentation will describe the recent progress, achievements, and future prospects of ML applications at SACLA.

Speaker: Eito Iwai (Japan Synchrotron Radiation Research Institute, RIKEN SPring-8 Center)

TUI6T01_slides.pdf

12:30 → 14:00 Lunch break

12:30 → 13:30 Lunch break

13:30 → 13:55 Design and Demonstration of a High Efficiency, High Power Density GaN-Based Solid-State RF Amplifier

RFHIC presents measured performance from its 150 kW, 500 MHz GaN-on-SiC Solid-State Amplifier system, for the 4th Generation Synchrotron Radiation (4GSR) project at Pohang Accelerator Laboratory. Results demonstrate 62% system efficiency, sub-0.25 dB gain flatness, sub-1° phase variation over 48 hours, MTTF exceeding one million hours, and validated graceful degradation under multi-module failure. The presentation compares GaN, LDMOS, and tube-based architectures across CW and pulsed regimes, quantifies facility-scale energy savings, and outlines RFHIC's GaN amplifier roadmap for next-generation light sources and pulsed linac applications.
This work was conducted under the 4GSR project, with PAL as a joint R&D partner and KBSI serving as the lead project administrator.

Speaker: Grace Cho (RFHIC Corporation)

14:00 → 16:00 MC2 : Photon Sources and Electron Accelerators

14:00 Attosecond FEL Physics

Following the first demonstration of isolated attosecond FEL pulses in 2018 and the Nobel prize in (tabletop) attosecond science in 2023, demand for attosecond x-ray pulses has increased exponentially.

This talk would review recent advances in attosecond pulse generation, including: attosecond lasing at LCLS-II; the first demonstration of attosecond super-radiance; and a measurement of FEL group velocity in the first attosecond pump / attosecond probe experiment at a free electron laser. These advances rely on the novel use of collective dynamics to shape the electron beam.

This talk would also provide an outlook for upcoming opportunities in attosecond science using linear accelerators, including:
HXR attosecond pulses and attosecond beams from plasma wakefield based bunch compression.

Speaker: Agostino Marinelli (SLAC National Accelerator Laboratory)

TUI2M03_talk_edited_version.pdf

14:30 Commissioning and performance of the ThomX compact compton source demonstrator

ThomX is a compact Compton-based X-ray source demonstrator constructed and operated at IJCLab on the Université Paris-Saclay campus (Orsay, France). The facility comprises a 70 MeV linac, a transfer line, an 18 m storage ring and an extraction line. At the interaction point, laser pulses stored in a high-finesse Fabry-Perot cavity collide with circulating electron bunches, generating X-rays with energies up to 90 keV. During the 2023-2025 commissioning campaigns, X-ray production was achieved with a stored laser power of about 90 kW and an average flux of approximately $10^{10}$ photons/s at 45 keV. These results confirm the feasibility of a compact, high-flux Compton source delivering hard X-rays in the 45-90 keV range. This contribution will outline the main challenges associated with compactness, low-energy operation and nonlinear beam dynamics. It will also present the recent advances in beam commissioning and X-ray source characterization. The demonstrated performances and perspectives toward the nominal regime of 1 nC bunch charge, 700 kW stored laser power and $>10^{12}$ photons/s X-ray flux will be discussed.

Speaker: Iryna Chaikovska (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

15:00 High charge operation and future upgrades of the APS-U injector chain

For swap-out operation in the APS-Upgrade storage ring, the injector must supply a full charge bunch in one shot. For 200 mA operation in 48 bunch timing mode, the required charge per bunch is 16 nC, which is challenging for the injector chain. In this paper we report on the present status of high charge operation and discuss upcoming improvements to increase the charge limit. We also propose two future upgrades to the APS-U injector chain: a high charge photoinjector for direct injection into the booster, and a high energy accumulator ring in the booster tunnel.

Speaker: Joseph Calvey (Argonne National Laboratory)

TUO2M04_edited_version.pdf

15:20 CLARA commissioning and first friendly user experiments

The CLARA facility at Daresbury Laboratory is a medium energy user facility for wide range of applications such as novel acceleration, cancer-therapy, and advanced diagnostics research. CLARA is currently finalising beam commissioning after an extended period of technical systems commissioning. During this period CLARA hosted its first set of “friendly” user experiments in its dedicated shielded user beamline, FEBE. Five different experiments were selected for the first user run, covering a range of applications including: advanced diagnostics measurements using coherent transition radiation (CTR) and optical transition radiation (OTR) stations; Very High Energy Electron (VHEE) cancer-therapy studies; beam-driven plasma wakefield acceleration studies related to next generation colliders. These experiments were conducted exploiting the full capabilities of the CLARA facility, including up to 250 MeV/c bunches with up to 250 pC per bunch at 100 Hz repetition rate, and with variable longitudinal compression regimes. The experiments chosen will also develop and prepare CLARA for the transition to a full user facility. Further user experiments are expected to be performed later in 2026, after final commissioning of the 120 TW laser system in FEBE, which will expand the range of experiments to include those combining electron beams and high-power lasers.

Speaker: Dr Mark Johnson (Science and Technology Facilities Council)

TUO2M05_edited_version.pdf

TUO2M05_talk_edited_version.pdf

15:40 SLS 2.0 commissioning progress

Commissioning of SLS 2.0, the first light-source storage ring employing a substantial number of permanent magnets to realize a compact multi-bend achromat lattice, began in January 2025. As reported at IPAC'25, the nominal beam current of 400 mA was achieved within the first three months of accelerator-dedicated commissioning. Since then, significant additional progress has been made, such as beamline commissioning during the subsequent three-month period, realignment of the storage ring, and commissioning of the fast orbit feedback system. The Swiss Light Source facility upgraded to fourth-generation has reached a level of availability sufficient to begin user operation, delivering high-brightness photon beams to twelve operational beamlines. Two weeks of friendly user operation in July and one month of external user service in November–December were successfully completed. It is currently in shutdown for the further installation of planned photon sources and is scheduled to resume operation in spring 2026. We present the commissioning results, lessons learned, and experience gained during the initial user operations.

Speaker: Masamitsu Aiba (Paul Scherrer Institute)

TUO2M06_edited_version.pdf

14:00 → 16:00 MC7: Accelerator Technology and Sustainability

14:00 Innovate for Sustainable Accelerator Systems (iSAS)

Particle accelerators have become essential instruments for fundamental research and also to improve our health, high-tech abilities or safety. Accelerating particles to high energies require a large amount of energy and energy sustainability is an unavoidable challenge for future accelerators. Among several solutions developed to minimize energy consumption, the project Innovate for Sustainable Accelerator Systems (iSAS) focuses on energy-efficient SRF R&D. It aims to develop core SRF technologies with the largest leverage for energy savings. This european-funded project (HORIZON-INFRA-2023-TECH-01-01) aims to develop, prototype and validate SRF technologies so that accelerators can operate with the same or improved performance while using significantly less energy.
iSAS is devoted to three main technology areas, aiming to save energy
• from the RF power with fast reactive tuners, smart LLRF system, optimized fundamental and HOM couplers,
• from the cryogenics, with Nb3Sn on Cu cavity operating at 4.5 K,
• from the beam, with energy-recovery linacs.
The project envisages three activities to introduce these technologies into the design of a sustainable LINAC cryomodule, into existing research facilities and into industrial solutions.

Speaker: Maud Baylac (Laboratoire de Physique Subatomique et de Cosmologie)

TUI7T01_edited_version.pdf

14:30 The tristron, a new paradigm in high-efficiency RF power generation

The tristron was already proposed many years ago but was never developed to a stage, where it could be mass produced. Based on IOTs, the tristron promises to achieve RF efficiencies above 90% for a wide frequency and power range. Building on the development of high-efficiency klystrons, CERN is proposing this new device as the power source of choice for future colliders like the FCC. The talk will focus on the conceptual design of the tristron and outline the development that is starting together with industry.

Speakers: Aditya Singh Thakur (European Organization for Nuclear Research), Audrey Piccini (European Organization for Nuclear Research), Chiara Marrelli (European Spallation Source), Graeme Burt (Lancaster University), Igor syratchev (European Organization for Nuclear Research), Lee Millar (European Organization for Nuclear Research), Nuria Catalan-Lasheras (European Organization for Nuclear Research), Zaib Un Nisa (Lancaster University)

TUI7T02_edited_version.pdf

TUI7T02_talk.pdf

TUI7T02_talk.pptx

15:00 Scale up in length of Nb3Sn accelerator magnets: the experience of MQXF coils

Future high-energy proton colliders will require high-field accelerator magnets beyond the capabilities of Nb-Ti technology. The Nb₃Sn quadrupole magnets developed for the High-Luminosity LHC upgrade represent the first large-scale application of this technology in an operational accelerator. Following an extensive short-model R&D program—comprising about 40 coils and seven 1.5 m-long magnets—a full-scale prototyping phase established the basis for series production. The series fabrication phase is now nearing completion, with more than 120 coils of 4.5 m length produced within the US-Accelerator Upgrade Project and over 70 coils of 7.2 m length manufactured at CERN. This large-scale effort across several manufacturing sites provides a unique insight in the scalability of Nb₃Sn technology in terms of magnet length, production volume and throughput. We present an overview of the production timeline, learning curve, major non-conformities and process improvements focusing on coil fabrication.

Speaker: Susana Izquierdo Bermudez (European Organization for Nuclear Research)

TUO7T01.pdf

TUO7T01.pptx

TUO7T01_talk_edited_version.pdf

15:20 An ultra-high brightness cryogenic C-band RF gun for ultra-fast electron diffraction applications

The electron source at the MOTHRA beamline is a novel 0.5-cell cryogenic C-band photoinjector designed to operate at gradients up to 200 MV/m. This work reports on recent developments toward implementing a load lock and modular cathode backplane that enables the insertion and testing of next-generation photocathode materials and structures under high-field, cryogenic operating conditions. The combination of a high launch field, low intrinsic emittance cathodes, and cryogenic temperatures is expected to significantly increase the achievable beam brightness. We present the current design status, experimental progress, and performance measurements of the cryogenic photoinjector with the modified backplane. In addition, we discuss beam-dynamics optimization for operating the source in an ultrafast electron diffraction (UED) configuration, where the high gradient and low intrinsic emittance offer a promising pathway to MeV-scale UED with exceptional brightness and temporal resolution.

Speaker: Chad Pennington (University of California, Los Angeles)

TUO7T02_edited_version.pdf

TUO7T02_talk_edited_version.pdf

15:40 Analysis of LCLS-SC commissioning and operational quenches

LCLS-SC achieved first light in 2023, and continues to ramp up performance. The linac consists of 35 cryomodules at 1.3 GHz, plus two cryomodules operating at the 3rd harmonic (3.9 GHz). The high repetition rate linac has been operating at 3.8 GeV regularly since 2024. As with any SRF machine, quenches occurred both during commissioning (as a part of normal processing), and during normal operations (tuning and beam delivery). After several years of operation, there are now thousands of quench events that can be analyzed and mapped to machine performance. In this work, quench rates in all cavities in the linac are identified and compared to operational quench rates and gradient limits.

Speaker: Nicole Neveu (SLAC National Accelerator Laboratory)

TUO7T03_edited_version.pdf

TUO7T03_talk_edited_version.pdf

16:00 → 18:00 Poster session

16:00 100 keV Hybrid DC-RF Injector based on the Ultracold Electron Source

Time resolved crystallography of biological systems has become increasingly popular with the development of X ray Free Electron Lasers. In addition to X rays, high quality electron beams can also be used for diffraction. However, the large lattice constant of protein crystals poses strict requirements on the transverse emittance of the electron beam. The ultracold electron source is a significant advance in the quest towards low emittance electron beams. By using laser cooled Rb atoms as the electron source, a source temperature in the order of 10 K can be obtained, which can enable a normalized emittance of 1 nm-rad at 1 fC bunch charge. We outline our progress towards commissioning of the 100 keV hybrid DC-RF injector based on the ultracold electron source. This design aims to bridge the gap between electron microscopy and high brightness photoinjectors; with the goal of building a robust instrument for time-resolved electron diffraction experiments of complex molecules.

Speaker: Ameya Patwardhan (Eindhoven University of Technology)

16:00 325 MHz digital low-level RF control system with dynamic gain adjustment for a dual-port RFQ

The Proton Radiation Effects Facility (PREF) was designed and constructed by the Institute of Modern Physics (IMP), Chinese Academy of Sciences. It aims to provide low to medium energy protons from 10-60 MeV, which is an excellent range for experimental research on the displacement damage effect studies. The facility uses a compact, four-vane RFQ with dual-port as its injector, powered by two 300 kW solid-state amplifiers (SSAs). The RF field stability requirement is ±1% for the amplitude during flat-top. To meet these requirements, a 325 MHz digital low-level RF control system has been developed based on a field-programmable gate array (FPGA)and CompactPCI bus. To compensate the inherent nonlinearity of the SSAs, a dynamic loop gain adjustment mechanism was implemented. Feedforward and feedback control strategy are also employed. The results of the 48-hour long-term stability test show that the amplitude stability is less than ±0.2%, significantly exceeding the design specification. This poster presents the design, implementation, and performance testing.

Speaker: Ruifeng Zhang (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 A Dual-System Approach for Upgrading the Helium Cryogenic System at the Taiwan Photon Source

The current helium cryogenic system at the Taiwan Photon Source (TPS) is a single-plant configuration designed to support up to four superconducting RF cavities. While reliable in routine operation, the single-system architecture poses a critical vulnerability: any warm-up maintenance, scheduled overhaul, or unexpected repair requires a complete shutdown of the cryoplant, interrupting helium supply and affecting SRF availability.
To eliminate this single-point risk, TPS proposes a dual-system approach for upgrading its helium cryogenic infrastructure. By adding a second, fully independent refrigeration system, continuous helium supply can be maintained under all conditions—including planned servicing, component replacement, or unforeseen failures. With either cryoplant capable of sustaining essential SRF cooling on its own, the dual-system configuration ensures uninterrupted operation and greatly enhances overall facility resilience. This upgrade is essential for supporting long-term SRF stability and future accelerator development at TPS.

Speaker: Ping-Shun Chuang (National Synchrotron Radiation Research Center)

16:00 A full-energy electron injector for the EIC based on proton-driven plasma-wakefield acceleration

The Electron-Ion Collider (EIC) is presently under construction at Brookhaven National Laboratory, and will collide electrons with an energy of up to 18 GeV with hadrons of up to 275 GeV. In this work we evaluate the feasibility of using proton-driven plasma wakefield acceleration to accelerate electron bunches to full energy for injection into the EIC Electron Storage Ring. Particle-in-cell simulations are used to identify a scheme which allows the acceleration of electron bunches with high charge and low energy spread, building on previous studies which investigated the potential energy gain.

The RHIC “BLUE RING”, which accelerates hadrons in the same direction as the electrons of the EIC, can be exploited to drive the plasma wakefields, offering the potential to significantly reduce the capital cost of the EIC facility. We show that by increasing bunch population to $3\times 10^{11}$, and moderate compression of the drive bunch to 2.5 cm, high accelerating fields can be achieved by exploiting the self-modulation of the proton beam, as harnessed by the Advanced Wakefield Experiment (AWAKE) project at CERN. To facilitate the use of a plasma discharge, we consider the possibility of using different ions, instead of rubidium.

Speaker: Helena Jaworska (Heinrich Heine University Düsseldorf)

TUP3043_edited_version.pdf

16:00 A High-Power 805 MHz RF System Based on Solid-State GaN on SiC HEMT Amplifiers for the LANSCE High-Power Proton Accelerator

The Los Alamos Neutron Science Center (LANSCE) accelerator is an 800 MeV, high-power proton machine that services numerous experimental areas that include proton radiography, spallation neutron source targets, and an end station dedicated to isotope production. Now in its sixth decade of operation, LANSCE accelerates its H- beam from 100 to 800 MeV using an 805 MHz coupled cavity linear accelerator that is powered by 44, 1.25 MW 805 MHz klystrons that were developed 58 years ago. With operations planned for several more decades, modernization of the LANSCE 805 MHz high-power radiofrequency (HPRF) system is needed. Los Alamos has embarked on a forward-looking study to assess the wisdom of utilizing high-power solid-state amplifiers for this effort. Leading edge, high voltage Gallium Nitride (GaN) on Silicon Carbide (SiC) high electron mobility transistors (HEMT) are now capable of operating at multi-kilowatt peak powers (5 kW in this case) at the pulse width (1 ms) and repetition rate (120 Hz) needed by LANSCE. We will give an overview of the status of this project and how it fits in with LANSCE 805 MHz HPRF system modernization efforts.

Speakers: John Lyles (Los Alamos National Laboratory), Michael Brown (Los Alamos National Laboratory), Steven Russell (Los Alamos National Laboratory)

16:00 A modular optimization framework for 4th generation Light Source Lattice Design: synergizing physics priors and statistical learning

The design of fourth-generation synchrotron light sources based on Hybrid Multi-Bend Achromat (H-MBA) structures faces significant challenges due to the high dimensionality of design variables and the strong nonlinear effects induced by strong focusing forces. The traditional paradigm of manual matching followed by stepwise fine-tuning'' encounters bottlenecks in optimization efficiency and physical interpretability. This paper proposes a modular optimization framework that fuses physics priors with statistical learning to achieve synergistic optimization of linear optics and nonlinear dynamics. The framework uses Twiss parameter evolution as an intermediate physical representation, and a physics-prior screening mechanism driven by linear transport is combined with the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). This approach identifies stable periodic solutions with reduced natural emittance within minutes and shows reproducible efficiency gains over manual initializations. Machine-learning classifiers trained on the generated dataset perform high-confidence pruning of the solution space and retain high-quality solutions. A local trust region constructed around thesepromising solutions'' introduces the Sequential Model-based Algorithm Configuration (SMAC) strategy based on Random Forests for refined iteration. This method provides an efficient and intelligent pathway for complex, high-dimensional lattice design.

Speaker: LINGLONG MAO (Shanghai Institute of Applied Physics, Chinese Academy of Sciences)

TUP2623_edited_version.pdf

16:00 A novel approach to RF power coupling in Radio-Frequency Quadrupole (RFQ) structures: built-in coaxial double-loop coupling port

Efficient and reliable RF power couplers in accelerating cavities require precise impedance matching and mechanical stability to ensure optimal beam energy transfer. In radio-frequency quadrupole (RFQ) accelerators, power is commonly delivered using waveguide iris or coaxial loop couplers. Iris couplers can handle high RF power but lack tunability, while coaxial loop couplers offer tuning flexibility but are limited in power handling and thermal performance. We propose a new RFQ power coupling concept utilizing a single input coaxial center-fed double-loop antenna built into a vane in an RFQ structure . The design integrates back-to-back loops into the RFQ vanes, fed by a TEM coaxial transmission line with standard 50-Ω characteristic impedance. The configuration can allow straightforward and easy ceramic window replacement without retuning, and coupling strength is adjusted with protruding tuning rods. Numerical simulations, performed with both a simplified RFQ model and the Spallation Neutron Source RFQ, demonstrate improved RF performance and reduced dipole mode excitation. The results establish the coaxial double-loop coupler as a practical alternative for high-power RFQ coupling applications.

Speaker: Sung-Woo Lee (Oak Ridge National Laboratory)

TUP7320_edited_version.pdf

16:00 A novel magnetic measurement system for cryogenic permanent magnet undulator

A standardized magnetic measurement system exists for evaluating the field characteristics of conventional insertion devices, including in-vacuum undulators designed for NSLS-II, which employ a rectangular measurement window. A In-Vacuum Magnetic Measurement System (IVMMS) valid for 1.5 m long CPMU was developed during the NSLS-II project. However, in the case of cryogenic permanent magnet undulators (CPMUs), each facility implements its own design, and no commercially available measurement apparatus currently exists. At NSLS-II, we intend to retain a side rectangular window for room-temperature characterization. Consequently, a completely new in-vacuum Hall probe system good for longer devices than 1.5 m has been developed to interface with this window. This paper presents a preliminary design of the in-vacuum Hall probe measurement bench, designed to characterize a 3 m-long CPMU planned for the NEXT-III (NSLS-II Experimental Tools III) project beamline.

Speaker: Toshiya Tanabe (Brookhaven National Laboratory)

TUP7360_edited_version.pdf

16:00 A novel method for measuring the energy spectrum of an inverse Compton scattering source based on nuclear resonance fluorescence

We proposed a novel method of using nuclear resonance fluorescence (NRF) as a probe for spectrum measurements. By utilizing the continuous tunability of an ICS source, NRF photons can be excited at different points across the spectrum. The shape of the energy spectrum can then be effectively scanned and reconstructed by recording the relative NRF yields at different energy points. The feasibility of the proposed method was validated by Geant4 simulations of measuring NRF photon emission from 56Fe irradiated by an ICS source. The simulation results showed high precision for quasi-monochromatic gamma ray spectrum measurements, with a normalized root mean square error (NRMSE) of less than 5%. To maintain a sufficient signal-to-noise ratio (SNR) during the measurement, the energy resolution of detectors is suggested to be less than 1% of the energy being measured. Given an energy tuning precision of Delta E, the minimum measurable width of the energy spectrum, in terms of standard deviation, can reach 0.85 Delta E.

Speaker: Jin Lin (Tsinghua University)

TUP2688_edited_version.pdf

16:00 A roadmap towards 0.1 um thermionic-cathode-based DC gun for FEL applications

The SACLA linear accelerator employs a DC gun with a thermionic cathode, valued for high beam quality, excellent operational stability, and minimal maintenance. We present a comprehensive beam-dynamics analysis of this source and outline a path toward sub-micrometer (0.1 um) normalized emittance. We provide analytical estimates and particle tracking results for four dominant emittance-growth mechanisms: (1) image-charge forces at the cathode, (2) nonlinear space-charge forces arising from imperfect beam-edge geometry, (3) aberrations of the accelerating field, and (4) solenoid-field aberrations caused by longitudinal–transverse momentum exchange. From these contributions we derive a closed-form expression for correlated emittance growth and identify an ''interference'' term that amplifies the net emittance when space-charge and solenoid effects act together.

To mitigate this growth, we propose a compact hybrid magnet that tightly confines the axial field, enabling placement immediately downstream of the gun while keeping the field on the cathode negligible. The device uses permanent ring magnets positioned symmetrically around a central solenoid, allowing precise shaping and longitudinal ''squeezing'' of the field profile. The results offer a practical roadmap for SACLA and transferable insights for low-voltage continuous-wave very-high-frequency injectors and superconducting RF electron guns.

Speaker: Vitaliy Goryashko (Uppsala University)

16:00 A Status update of LhARA, an Accelerator-driven Radiobiology Research Initiative

LhARA is multidisciplinary collaboration that is embarking on an initiative to use laser-driven ions in a hybrid acceleration scheme with a fixed-field alternating gradient (FFA) accelerator to deliver a systematic radiation biology programme and lay the technological foundations for the transformation of proton and ion beam therapy. LhARA is in an R&D phase of activity that is overseeing the development of a number of accelerator technologies to support our initiative, as well as conducting experiments in the Proof-of-Principle for LhARA and Radiobiology (PoPLaR) programme that is examining the effect of laser-driven ions on biological tissue samples. Here, we present a summary of the most recent updates from the LhARA collaboration, including Gabor plasma lenses for beam capture and focusing, magnetic beam delivery schemes for variably-sized, transversely uniform beam profiles, the FFA in LhARA’s second stage to reach clinically relevant ion energies, and an overview of the PoPLaR experiment.

Speaker: Hywel Owen (Science and Technology Facilities Council)

TUP8018_edited_version.pdf

16:00 accelECR: the Early Career Researcher network in Accelerator Science and Technology

Early-career researchers (ECRs) are central to the advancement of accelerator science and technology, contributing across all areas - from R\&D, theory, and design to experiment, commissioning, and operation - at all scales, from small medical accelerators to large colliders. While accelerator projects are often high-cost, long-timescale, and resource-intensive, ECR perspectives are underrepresented in strategic planning and decision-making. Following the example of particle physics (ECFA ECR) and nuclear physics (NuFFER), the accelerator science and technology community now has its own ECR network: accelECR. Through regular seminars and community-driven events,accelECR fosters knowledge exchange, promotes inclusivity, and improves skill transferability across the field. It also serves as a collective platform through which accelerator ECRs can engage with high-level strategy and decision-making in the field. The motivation, organization, and framework of accelECR are presented in this contribution.

Speaker: Lina Valle (European Organization for Nuclear Research)

TUP8035_edited_version.pdf

16:00 Acceleration gradients in dielectric laser accelerators with single and double triangular-shaped gratings

The acceleration of electrons in dielectric laser accelerators (DLAs) with a triangular ridge profile on the structure's surface was investigated. The aim was to to determine the maximum acceleration gradients when using DLA with triangular profiles. Single chip structures with a triangular profile, both transparent and reflective to laser radiation, were considered. The acceleration gradients were found as a function of the base angle of the grating ridge. Left-handed and right-handed variations of these triangular structures, differing in the ridge tilt direction, were also examined. Electron acceleration using double-triangular structures, consisting of various combinations of transparent and opaque structures, was also conducted. The maximum values of energy gain and acceleration gradients for all investigated combinations of single and double chip structures were determined and quantified. The effect of the longitudinal displacement of one structure relative to the other in a double configuration on the change in energy gain and acceleration rate was also studied. Based on the obtained results, it can be stated that in DLAs with a triangular profile, acceleration rates can reach 400 MeV/m.
This study is supported by the National Research Foundation of Ukraine under the program “Excellent Science in Ukraine” (project # 2023.03/0182).

Speaker: Oleh Svystunov (National Science Center Kharkiv Institute of Physics and Technology)

16:00 Accuracy and stability of lattice correction for the pgraded APS

A well-corrected lattice is essential for the performance of any modern synchrotron light source. Beyond the standard motivations -- such as preserving optimized nonlinear dynamics and maintaining sufficient dynamic and momentum acceptance -- accurate lattice correction is particularly important in APS-U for achieving the predicted emittance reduction associated with insertion-device radiation. In APS-U, lattice characterization relies on response-matrix fitting. Simulations performed during the design phase indicated that the achievable accuracy of such measurements would be limited to the few-percent level, thereby constraining the ultimate lattice correction precision. This paper presents the typical results of the APS-U lattice correction, examines approaches to improving lattice measurement accuracy, and discusses the long-term stability of the corrected lattice.

Speaker: Vadim Sajaev (Argonne National Laboratory)

TUP2308_edited_version.pdf

16:00 Advanced externally seeded FEL schemes for high-repetition-rate operation at SHINE

Externally seeded free-electron lasers (FELs) are promising approaches for generating fully coherent soft-X-ray radiation. Their extension to shorter wavelengths and MHz-level repetition rates is, however, constrained by the limited availability of high-repetition-rate seed lasers with sufficient energy modulation. Recent self-amplification and direct-amplification experiments at the Shanghai Soft X-ray FEL facility have significantly relaxed the peak-power requirement for high-gain harmonic generation (HGHG) and opened a practical path toward echo-enabled harmonic generation (EEHG). Using the SHINE bypass line, three compatible high-repetition-rate seeded-FEL configurations are explored: self-modulation cascaded HGHG, self-modulation EEHG, and direct-amplification-driven EEHG. Numerical simulations indicate that these schemes can provide flexible routes toward MHz-level operation with harmonic generation beyond the 30th order. A common modulator-chicane layout is proposed to preserve compatibility among the candidate modes and to support future optimization and experimental implementation at SHINE.

Speaker: Hanxiang Yang (Shanghai Advanced Research Institute)

TUP2653_edited_version.pdf

16:00 Advancements and dosimetry of a single-turn extraction for FLASH radiotherapy studies at ELSA

Ultra-high-energy electrons are used to investigate their effects on cell samples in nanosecond to microsecond pulses at the electron accelerator facility ELSA. This may allow highly efficient treatment of deep-seated tumors through the FLASH effect. Previous studies at ELSA using an inital extraction mode with 250 ns long pulses from the 1.2 GeV booster synchrotron demonstrated the suitability for FLASH radiotherapy studies. A newly developed single-turn extraction scheme from the stretcher ring now enables access to beam energies of up to 3.2 GeV with pulse lengths of approximately 330 ns and improved beam stability. In preparation for upcoming cell irradiation studies with this new extraction mode, precise dose determination is carried out by combining radiochromic film measurements with Geant4 simulations over the full energy range from 1.2 GeV to 3.2 GeV. Depth-dose curves from the previous and current operation modes are compared. Additionally, studies of Cherenkov radiation are performed to evaluate its potential for beam characterization.

Speaker: Leonardo Thome (University of Bonn)

TUP8009_edited_version.pdf

16:00 Advances in large-scale non-evaporable getter coating techniques for the Hefei Advanced Light Facility

The Hefei Advanced Light Facility (HALF), currently under construction, is a fourth-generation synchrotron radiation source operating in the low-energy region (2.2 GeV) and based on diffraction-limited storage ring technology. The storage ring employs a modified hybrid 6BA lattice with a beam emittance of 86.3 pm·rad and consists of 20 achromat cells with a total circumference of approximately 480 meters. To meet the ultra-high vacuum environment of the storage ring, non-evaporable getter (NEG) films are applied to the inner surfaces of the vacuum chambers to provide distributed pumping capability and to reduce surface outgassing and photon-stimulated desorption. Large-scale NEG coating of the HALF storage ring vacuum chambers has been officially initiated. This paper presents an overview of the HALF storage ring vacuum system and provides a systematic description of the large-scale NEG coating system, including the equipment configuration and control system. In addition, a storage system for coated vacuum chambers is described to ensure film quality prior to installation, which provides technical support for subsequent assembly and commissioning.

Speaker: Xiaopeng Xu (University of Science and Technology of China)

TUP7681_edited_version.pdf

16:00 Alignment error analysis based on HALF lattice

The storage ring of the Hefei Advanced Light Facility has a circumference of approximately 480 m and consists of 20 hybrid six-bend achromatic (H6BA) lattice units with a natural emissivity of approximately 86 pm·rad. High-brightness diffraction-limited light sources place higher demands on alignment. This paper focuses on the HALF lattice and uses the Accelerator Toolbox (AT) utility program for high-fidelity error analysis and calibration simulation. Sensitivity assessments for different error sources are presented, and the optical degradation laws under overall beam misalignment and superposition states are investigated. The usability boundary under uncorrected conditions is also given.

Speaker: qiuyu zhang (University of Science and Technology of China)

16:00 Amplitude reproducibility of the self-modulation instability in a plasma wakefield accelerator

In AWAKE, the wakefields - and therefore the accelerating gradient - are generated through the self-modulation of a long, 400GeV proton bunch from the SPS. We present here the first experimental measurement of the event-to-event reproducibility of the wakefield amplitude produced by the self-modulation process.
Using two independent diagnostics, i.e., rms size of the bunch downstream of the plasma, and local plasma light emission [1], we find that when SM is seeded, variations of these two parameters are small, suggesting that variations of the amplitude of the wakefields are also small. Moreover, we find that the relative event-to-event variations are smaller at saturation than during growth. This is consistent with previous numerical simulation results [2].
These results demonstrate that seeding does not only make the phase of the wakefields reproducible from event-to-event [3], but also their amplitude, a key requirement for producing high-quality accelerated bunches with this acceleration scheme.

Speaker: Arthur Clairembaud (Max Planck Institute for Physics)

16:00 Analysis and compensation of the insertion device effects in the HALF storage ring

The Hefei Advanced Light Facility (HALF) is a diffraction-limited storage ring light source with a beam energy of 2.2 GeV. There are 13 insertion devices (IDs) will be installed in the storage ring, which will have severe impacts on the low-energy beam. Especially for the long-period EPU, the non-linear effect will significantly reduce the dynamic aperture of the storage ring. In this paper, the IDs effects are analyzed in detail with kick-map models for the HALF storage ring. Each ID is compensated using a local quadrupole feedforward method. For some EPUs with significant impacts, additional compensation is provided through the shimming of current strips. The analysis and compensation results will be presented in this paper.

Speaker: Zhouyu Zhao (National Synchrotron Radiation Laboratory)

TUP2678_edited_version.pdf

16:00 Analysis and refurbishment of a radiation-damaged undulator

Synchrotron radiation facilities impose stringent requirements on the magnetic field quality, stability, and lifetime of undulators. During long-term operation of a beamline at the Shanghai Synchrotron Radiation Facility (SSRF), a gradual degradation of photon-beam performance was observed. To identify the cause, the cryogenic permanent magnet undulator of this beamline was warmed up and re-measured at room temperature during the summer shutdown. The on-axis field was found to be most strongly attenuated in the upstream region, with a maximum reduction of about 20% that gradually relaxed towards the downstream end. In addition, several sharp local drops of the magnetic field were detected in the central section. Visual inspection revealed pronounced melting holes in the copper foil in this area, indicating localized electron-beam impacts that likely damaged the underlying magnets and led to the abnormal field reduction. This paper presents the magnetic measurement results and the longitudinal attenuation pattern of the radiation-damaged undulator, and describes how local magnet replacement, re-shimming, and re-measurement were used to refurbish the device, providing a reference for future operation, maintenance, and radiation-protection design of similar undulators.

Speaker: jinya chen (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

TUP7698_edited_version.pdf

16:00 Analysis of beam loading effect of dark current in C-band photocathode electron gun

In the research on high-gradient photocathode electron guns, the existence of dark current not only affects the measurement of photo-beam but also causes problems such as secondary electron multiplication and an increased difficult of condition. In this paper, the sources of dark current emission inside the electron gun and their impact duiring the power test are discussed through simulations. Additionally, combined with the test results from the C-band electron gun test platform in the pre-research project of the Southern Advanced Photon Source, the beam loading effect introduced by dark current is analyzed. The results show that when the dark current in the test is > 10 mA, it will increase the coupling parameters of the cavity and reduce the cathode accelerating field gradient.

Speaker: Shengjin LIU (China Spallation Neutron Source)

TUP2697_edited_version.pdf

16:00 Analysis of slice energy spread increased by intra-beam scattering at the SHINE Injector and Linac

Intra-beam scattering (IBS) can substantially enhance the slice energy spread of high-brightness electron beams, thereby degrading the performance of free-electron laser (FEL) facilities. This effect is particularly detrimental for advanced operation modes such as self-seeding, which impose stringent requirements on beam longitudinal coherence. Consequently, an accurate evaluation of IBS growth in both the injector and the main linac is essential. SHINE, the first superconducting-linac–based FEL facility in China, has recently completed beam commissioning up to the first bunch compressor (BC1). In this work, we present a theoretical and numerical analysis of IBS-induced slice energy spread growth throughout the SHINE injector and linac. The analytical estimates show good agreement with start-to-end simulations, confirming that IBS leads to a significant increase in slice energy spread already at the injector stage. These results highlight the necessity of incorporating IBS considerations into the beam dynamics design and optimization of high-repetition-rate FEL facilities such as SHINE.

Speaker: Wencai Cheng (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

TUP2646_edited_version.pdf

16:00 Analytical calculation of transverse emittance and Twiss parameters

Achieving plasma-based accelerators for users demands careful control not only of the beam energy and energy spread, but also of transverse beam properties such as emittance, size, and divergence. Since plasma-based accelerators typically produce beams with significantly larger energy spread and emittance than conventional RF accelerators, several questions remain to be addressed, particularly, the transverse beam dynamics. In this article, it is presented an analytical description of the transverse beam properties evolution in a constant-focusing channel representing a plasma density plateau assuming a finite energy spread. The resulting expressions provide qualitative and quantitative guide to understand the transverse beam dynamics under these conditions.

Speaker: Samuel Marini (Commissariat à l'Énergie Atomique et aux Énergies Alternatives)

TUP3034_edited_version.pdf

16:00 Analytical solenoid matching routines with coolpy

Muon colliders require strong beam cooling to reduce the large phase space of muon beams produced from pion decay. The final stage of ionization cooling employs high-field solenoids, absorbers, and RF cavities, where precise beam matching is essential to avoid emittance growth. In this work, we present a beam-parameter–based approach to design and optimize solenoid lattices for the final cooling channel. The method models realistic solenoid fields and solves the coupled beam envelope equation while accounting for momentum changes in absorbers and RF systems. To implement this approach efficiently, we developed the Python package coolpy, which computes the evolution of Twiss parameters and optimizes matching coil settings. Two case studies demonstrate matched beam transport in solenoid-based beamlines.

Speaker: Paula Desire Valdor (European Organization for Nuclear Research, University of Groningen)

TUP3001_edited_version.pdf

16:00 ANTECHAMBER TYPE VACUUM CHAMBER COATED WITH NON-EVAPORABLE GETTER FILMS

To coat the inner surface of antechamber type vacu-um chamber for Hefei Advanced Light Facility (HALF) with nonevaporable getter (NEG) fillm, a dedicated magnetron sputtering setup has been prepared at National Synchrotron Radiation Laboratory (NSRL). The magnetron sputtering device and the coating method are introduced in this paper. The properties of the films were tested. This coating method has been proved to be feasible and ensures the stability of the discharge and the reliability of the NEG film quality, which satisfy the stringent engineering requirements of HALF. This study may also offer a reference for similar vacuum chamber coating applications.

Speaker: Tianlong He (University of Science and Technology of China)

16:00 Application of deep learning methods for insertion device effects in the SSRF

A deep-learning-based feedforward scheme has been developed to compensate insertion-device (ID) effects in the Shanghai Synchrotron Radiation Facility (SSRF). Neural networks predict orbit and betatron-coupling perturbations caused by ID gap and phase changes. The orbit model reduces residual closed-orbit distortion (COD) to below 2 um and shortens preparation time by about a factor of 50 compared with conventional feedforward-table measurements. A coupling model trained with turn-by-turn (TBT) beam-position-monitor (BPM) data reaches an R^2 value above 0.95. These results show that deep learning can support fast and reproducible ID compensation during light-source operation.

Speaker: Xinzhong Liu (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

TUP2709_edited_version.pdf

16:00 Application of LSTM autoencoder to the 10 kHz storage ring orbit data

In NSLS-II storage ring, the 10 kHz orbit data are always available and can be collected at any time interval. At this moment, they are being collected every 10 minutes to review the machine stability status or investigate orbit related issues impacting user satisfaction. To improve the machine performance, we are studying the machine learning techniques with which we can detect any orbit stability issue as early as possible. As one of the strong candidates, we are testing models constructed by the long short-term memory (LSTM) autoencoder from the orbit data. In this paper, we present the optimized LSTM autoencoder parameters and the test results.

Speaker: Ihar Lobach (Brookhaven National Laboratory)

TUP2340_edited_version.pdf

16:00 Application of magnetic-alloy-loaded cavities beyond 10MHz

Magnetic-Alloy-loaded cavities have been used for many applications; beam accelerations of high-intensity proton and heavy ion beams, beam manipulations, medical accelerators and anti-proton decelerations. The material has a large permeability and the cavities have bandwidth below approximately 10 MHz. Using an external inductor for reducing the effective inductance of a cavity system, the cavity bandwidth can be moved beyond 10 MHz. The higher harmonic cavity is required in J-PARC Main Ring to enlarge the longitudinal beam emittance before reaching the flat-top energy. For the slow extraction, the emittance growth will be inevitable to suppress the beam instability. For Hyper-Kamiokande neutrino experiment, high-intensity beam with lower peak current will be required to avoid the event-pile-up at a new intermediate detector (IWCD). In this paper, we present the emittance control scenario with the cavity, beam effects on it, and design of a new VHF RF system.

Speaker: Yasuyuki Sugiyama (High Energy Accelerator Research Organization)

TUP7625_edited_version.pdf

16:00 APS storage ring solid state amplifier upgrade current status

Radiofrequency (RF) power for the Argonne Advanced Photon Source (APS) storage ring (SR) and Booster cavities is currently supplied by multiple klystrons. APS is in the process of transitioning to 160 kW solid state amplifier (SSA) system per SR cavity. Several SSA systems have already been delivered, and site acceptance testing (SAT) has been completed on four units. New 200 kW circulators have also been tested. A typical SAT waveguide setup is shown. Improvements have been implemented, including modifications to RF cable lengths to increase access clearance and reduce environmental power dissipation. During the initial tests, 60 Hz noise was observed on the monitoring spectrum. This issue was investigated, and a successful mitigation solution has been implemented. To minimize the risks and to validate both the new hardware and control software, one SSA system will be placed into operational service around January 2026. For this deployment, the SR RF system will be in a hybrid configuration, with the SSA powering one cavity while the remaining eleven cavities continuously being powered by klystrons. Several intermediate interfaces are required to bridge the existing infrastructure with the new SSA system. After the hybrid operation, RF power for the remaining three cavities in the same sector will be transitioned to SSAs too. The remaining two SR sectors, are planned for SSA conversion within the following few years, completing the multi-year APS SR RF system upgrade.

Speaker: Yong Luo (Argonne National Laboratory)

TUP2339_edited_version.pdf

16:00 ARIEL radioactive gas management system

The ARIEL facility expands TRIUMF’s isotope production by adding two new target stations operating in parallel with the existing infrastructure, enabling high-intensity Radioactive Ion Beam (RIB) production. At the core of this facility, a complex vacuum system is designed to maintain the conditions required for RIB production while safely managing radioactive gases generated during beam-material interactions. The activated gases from the target and RIB modules are continuously evacuated and transferred via a radioactive gas management system to storage tanks for controlled decay. The radioactive gas management system is designed to support parallel and independent target station operation, prevent cross-contamination between exhaust streams, enable future scalability, and provide fault tolerance to ensure uninterrupted operation in the event of equipment failure. This system incorporates controlled gas recirculation and sampling capabilities to ensure the collection of a uniform sample for radiological assessment prior to release to the nuclear ventilation system. In addition, this system is operated and controlled remotely, enabling remote control of devices, data archiving, and implementation of interlocks for machine protection. Overall, this system offers a robust solution for radioactive gas management in modern accelerator facilities. This work presents the key design features and operational principles of the ARIEL radioactive gas management system.

Speaker: Farhad Rahimi (TRIUMF)

TUP7356_edited_version.pdf

16:00 Assessment of RF System Capability in the J-PARC Main Ring Toward 1.3 MW Operation

The J-PARC Main Ring plans to increase its beam power from 830 kW to 1.3 MW for the Hyper-Kamiokande neutrino experiment by 2028. To enable this higher-power operation, the RF system has been upgraded by increasing both the number of cavities and the anode current of the tetrode tubes. However, the required anode current is now approaching the maximum capability of the tubes, and several associated power-supply systems are also nearing their operational limits.

Traditionally, the anode current has been estimated using a phasor diagram approach. As an alternative, we evaluate the current using LTspice simulations, which can incorporate the vacuum-tube characteristics, cavity impedance, and beam loading. We have constructed an LTspice model of the Main Ring RF system that includes the impedance of the magnetic alloy loaded RF cavity, two 600 kW tetrode tubes, and the beam current corresponding to eight bunches with a total intensity of 3.3 \times 10^{14} protons. This allows us to estimate not only the anode current but also the screen grid currents, and the simulation results have been compared with measurements.

In this paper, we present LTspice based RF system calculations for the Main Ring and evaluate the RF power requirements necessary to achieve 1.3 MW beam operation.

Speaker: Kiyomi Seiya (High Energy Accelerator Research Organization)

TUP7629_edited_version.pdf

16:00 ATSOA at CERN: A Hands On Accelerator Course in the EURO-LABS Framework

Beyond providing Transnational Access to major Research Infrastructures (RIs) across Europe, the European Laboratories for Accelerator Sciences (EURO-LABS) programme supports advanced training activities. Within this framework, an Advanced Training School on the Operation of Accelerators (ATSOA) is organised at CERN. The school targets students, young researchers, and professionals in the field of accelerator science, offering them a unique opportunity to participate in a week of hands-on training. Five CERN facilities — CLEAR, AD/ELENA, ISOLDE, PSB and LEIR — are involved in the training, allowing participants to familiarise themselves with different accelerator types and particle species. Under the guidance of experienced instructors, they carry out dedicated experiments designed to illustrate key physics concepts and operational principles that can be applied in their own work. This contribution gives an overview of the past schools and an outlook for future courses.

Speaker: Foteini Asvesta (European Organization for Nuclear Research)

TUP8014_edited_version.pdf

16:00 AttoSHINE: Generation of continuous-wave terawatt-scale attosecond X-ray pulses at SHINE

Attosecond X-ray pulses are essential for probing ultrafast electron dynamics in condensed matter systems, molecular processes, and strongly correlated materials. Recent progress in X-ray free-electron lasers (XFELs) has significantly advanced the generation of such pulses, opening new frontiers in ultrafast science. Building on this, the attosecond operation mode of SHINE, termed AttoSHINE, was recently developed through systematic design. Through comprehensive start-to-end simulations, we show that SHINE is capable of producing both soft and hard X-ray pulses with peak powers reaching the terawatt-scale by self-chirping mode.

Speaker: Chenzhi Xu (Shanghai Institute of Applied Physics)

16:00 AWAKE: preparing for physics beyond LS3

The AWAKE programme at CERN has evolved from its initial proof-of-principle phase to a comprehensive facility dedicated to advancing proton-driven plasma wakefield acceleration towards first particle-physics applications. In preparation for this next stage, AWAKE will undergo a major upgrade during CERN’s Long Shutdown 3 enabling the demonstration of electron acceleration to 6-10 GeV in a 10 m plasma source with controlled beam quality and validated scalability. Meeting the targets of 5-8% energy spread, 100 pC of accelerated charge and controlled emittance requires strong beam loading. This will be provided by a new RF photo-injector system equipped with two X-band structures and an optimized transfer line, delivering 150 MeV electrons with 5.75 um beam size at injection and 2 mm mrad normalized emittance. In parallel, the 400 GeV SPS proton bunch must reach full self-modulation in the first plasma source (‘self-modulator’) before the electrons are injected into the second plasma source (‘accelerator’). Extensive infrastructure modifications are already in progress, including the dismantling of the CNGS target area in order to create the space required for the upgraded AWAKE facility. We present the consolidated roadmap, the scientific goals, upgrade status and the key challenges associated with both the facility design and the experimental programme starting in 2029.

Speaker: Edda Gschwendtner (European Organization for Nuclear Research)

TUP3049_edited_version.pdf

16:00 Beam based alignment for bending magnets with transverse gradient

For storage rings, bending magnets with transverse gradient are commonly adopted to reduce the natural emittance. These magnets are typically offset quadrupoles, which generate combined dipole and quadrupole fields. Therefore, it is crucial to ensure that the beam travels at the designed off-axis position within the target magnets. Otherwise, particles would experience an additional dipole field due to the magnetic field feed-down effect, which could influence the beam dynamics. To determine the beam position in the bending magnets with transverse gradient, a beam-based alignment method is presented in this paper.

Speaker: Tao He (University of Science and Technology of China)

16:00 Beam based alignment of quadrupoles at HEPS

In modern storage ring light source, large offset of quadrupoles will degrade the beam quality in the ring. Beam based alignment(BBA) methods have been used widely in storage rings, to correct the orbit of the beam to the magnetic center of quadrupoles. The BBA algorithm and commissioning procedure at HEPS is described in this paper

Speaker: Yi Jiao (Institute of High Energy Physics, Chinese Academy of Sciences)

TUP2607_edited_version.pdf

16:00 Beam dump design and simulation for a 280-MeV electron linear accelerator

A 280-MeV electron linear accelerator has been designed to expand the research capabilities and applications of high-energy electron beams in Thailand. For commissioning and energy verification, two dedicated beam dumps are positioned downstream of the bending magnet. This work presents the simulation-based design and optimization of these beam dumps using the PHITS Monte Carlo radiation transport code. Different material configurations and geometries were evaluated to reduce prompt radiation and suppress secondary particle leakage. A multilayer structure combining high-Z and low-Z materials was found to provide effective energy absorption while confining photon and neutron secondaries within the shielding volume. The resulting radiation field in the tunnel meets all applicable safety criteria and regulatory limits. These results establish the validated baseline design for the beam dumps and support their transition to detailed engineering and fabrication.

Speaker: Kritsada Kittimanapun (Synchrotron Light Research Institute)

TUP7719_edited_version.pdf

16:00 Beam dynamics analysis of an electron microtron using General Particle Tracer

Electron microtrons are extensively employed as injectors for tabletop light source facilities. In this paper, a 5 MeV electron microtron is designed, and an external injection scheme is adopted to achieve a large stable longitudinal phase region. We investigated the beam dynamics of this microtron using General Particle Tracer (GPT). After optimization, the width of stable longitudinal phase region is approximately 40°, which is about four times larger than that of conventional internal-injection microtrons.

Speaker: Ms Fengyi Zhang (University of Science and Technology of China)

16:00 Beam Induced Fluorescence experiments for Ultra-High-Dose-Rate dosimetry in proton therapy

Ultra-High-Dose-Rate (UHDR) / FLASH radiotherapy with proton pencil beams requires particle fluxes that saturate current clinical dosimetry, such as ionisation chambers. Before UHDR proton therapy can be clinically implemented, novel dosimetry techniques must be developed that reduce the uncertainty on delivered dose to within clinical accuracies. One promising solution is to image gas Beam Induced Fluorescence (BIF), where the photon yield and transverse profile can be combined to calculate an absolute dose. Using the AGOR cyclotron at PARTREC, a superconducting isochronous cyclotron capable of providing clinical beam energies and dose-rates well into the UHDR regime, we are assessing the feasibility of using BIF for dosimetry. We show that the photon yield of Nitrogen remains linear with dose even at UHDR beam currents and examine the gas pressure-dependence in the range from 1e-3 to 100 mbar. When calculating doses, the width of the fluorescent region is compared to the real transverse beam size and methods to remove the background neutron and gamma counts from the CCD image without significantly altering the photon yield are described. These experiments are the first step towards progressing towards minimally invasive optical beam monitoring with a BIF-based dosimetry device, incorporating both transverse profile and energy deposition measurements, that could be used in proton therapy.

Speaker: Thomas Fogg (Particle Therapy Research Center)

16:00 Beam lifetime evaluation based on simulation of a vacuum pressure distribution for the SPring-8-II commissioning strategy through vacuum conditioning

SPring-8-II, a major upgrade of the third generation light source SPring-8, aims to achieve low emittance below 100 pm·rad and to reduce the power consumption of the light source machine. High magnetic field magnets for SPring-8-II naturally result in narrow bore diameters and are densely distributed. As a result, vacuum chambers along the entire storage ring are designed with narrow apertures, leading to low conductance, and space for vacuum equipment such as photon absorbers and vacuum pumps is limited. To meet these requirements, we employ small-diameter stainless steel chambers and discrete compact photon absorbers*. Non-Evaporable Getter (NEG) pumps are placed near photon absorbers to effectively evacuate photon stimulated desorption (PSD) gas. We simulated a pressure distribution within a SPring-8-II unit cell as a function of beam dose considering the degradation of a pumping speed of the NEG pump due to gas absorption. On the basis of these results, we evaluated the beam lifetime and formulated a commissioning strategy for increasing a stored current through systematic vacuum conditioning.

Speaker: Yosuke Ueda (Japan Synchrotron Radiation Research Institute)

TUP7690_edited_version.pdf

16:00 Beam manipulation of laser-driven proton beams using crystal channelling

In accelerator physics, particle channelling in crystals is a well-established phenomenon. By carefully selecting crystal orientation, particle’s trajectories can be controlled and guided along desired paths. Bent crystals have been used at worldwide particle accelerators as optical elements to steer charged particle beams.
Laser-induced accelerators could also benefit from the bent crystal properties. Laser-induced proton beams typically have very large angular divergence and energy spread as well as a large other particle background.
This paper investigates the possible uses of ultra-short bent silicon crystals for laser-driven proton beam manipulation at the ELIMED beamline at ELI Beamlines. Using PIC simulation input and a Monte Carlo simulation of the beamline, we explore different possible modes of operation – collimation, focusing, or steering in order to improve the beam qualities and increase the performance of the beamline.

Speaker: Helena Lefebvre (Extreme Light Infrastructure Beamlines)

16:00 Beam performance of the positron transport line for CEBAF positron upgrade

The Low Energy Recirculator Facility (LERF) at Jefferson Lab, formerly operated for the Free-Electron Laser program, has been proposed as the injector complex for the planned 12 GeV CEBAF positron upgrade (Ce+BAF), with an additional pathway to support a potential 22 GeV CEBAF electron upgrade. In this configuration, LERF would generate and pre-accelerate positrons to 123 MeV, matching the present injection energy into the North Linac. Due to the relatively large emittance expected from the positron source, a comprehensive acceptance study has been performed from LERF through the CEBAF recirculating linacs and beam transport lines to the experimental halls. The objective is to establish the positron phase-space acceptance and provide design feedback to the positron production and capture systems. Furthermore, given CEBAF’s capability to deliver highly polarized beams, spin-tracking simulations have been carried out including magnet imperfections, alignment errors, and synchrotron-radiation–induced energy spread. Particular attention is given to the evolution of the spin tune and the corresponding depolarization mechanisms along the beam delivery path, especially for providing longitudinal polarization at the experimental halls. These results inform injector design choices and assess the overall feasibility of delivering high-polarization positron beams in CEBAF.

Speaker: Salim Ogur (Thomas Jefferson National Accelerator Facility)

TUP5301_edited_version.pdf

16:00 Beam test of C-band Compact accelerating structure made of longitudinally-split two halves

Our 6 MeV medical C-band accelerating structure is assembles using the disk-stacked method, where multiple oxygen-free copper components are stacked along the beam axis. The design incorporates the side-coupled (SC) structure and the re-entrant structure with an accelerating gap at the center of the cavity. Due to the complex shape and the large number of components, there are difficulties in manufacturing efficiency. On the other hand, the longitudinally-split method divides the structure along a plane including the beam axis, independent of the number of cells, typically into only two halves or four quadrants, which significantly reduces the number of components. Building on the development experience of the quadrant-type X-band accelerating structure in the CLIC project, we have been working on the development of a compact, high-gradient, high-shunt impedance, SC-type C-band accelerating structure based on this configuration. We had reported previous work, fabrication of the full-scale structure, low-power RF test result, and preliminary first beam acceleration test at an energy level limited by the testing facility. In this presentation, we will report the progress of our work, RF conditioning and a high-power beam test in the actual operating conditions.

Speaker: Shu Takagi (Mitsubishi Heavy Industries Machinery Systems, Ltd.)

TUP7627_edited_version.pdf

16:00 Beamline optimization for Laser-Accelerated Ions

Laser-plasma acceleration can generate short, intense ion beams with energies up to several hundred MeV. However, the intrinsic large divergence and broad energy spectrum of these beams necessitate dedicated capture and transport beamlines to achieve high particle yields for applications. In this work, we use the LIGHT beamline with the PHELIX laser at GSI as an example case to develop and evaluate methods for optimizing and aligning such beamlines. Our focus is on future applications including injection into conventional accelerators and as a complement to traditional ion sources. Using the UNILAC at GSI as a reference case, we show that, for the present PHELIX laser intensities the number of laser-accelerated protons viable for SIS18 injection remains at least an order of magnitude below the typical bunch intensity of conventional linacs. Finally, by deriving and applying scaling laws for the transmission through the first capture element, we propose strategies for further improvement to bridge this gap in the future.

Speaker: Daniel Dewitt (Technical University of Darmstadt)

TUP3009_edited_version.pdf

16:00 Betatron radiation studies as a path to plasma undulators

The emission of betatron radiation from the beam-driven plasma wakefield acceleration is under consideration at SPARC_LAB [1], as a test-bed for the study and development of a plasma-based undulator device. In the framework of the EuPRAXIA ESFRI facility [2] and EuPRAXIA@SPARC_LAB project [3], there is a deep interest in developing a compact plasma-based user facility, not only for what concerns the acceleration module, but also for what is ancillary to the delivery of FEL radiation. In this regard, great efforts have been made to miniaturize for instance diagnostic stations, detection devices and transfer lines, e.g. based on active plasma lenses [4]. However, conventional undulators are still too cumbersome and expensive to meet the requirements of compactness and sustainability. Nowadays, advanced undulator concepts arouse great interest in pushing the frontier beyond conventional, magnet-based undulators. In this regard, a promising, alternative is represented by the betatron motion of electrons in an ion-channel to emulate an undulator device. This work will present a case study at SPARC_LAB.
[1] M. Ferrario et al., Nucl. Instr. and Meth. B 309, 183–188 (2013).
[2] Assmann, R. W. et al., Eur. Phys. J. Spec. Top. 229, 3675–4284 (2020).
[3] M. Ferrario et al., Nucl. Instr. and Meth. A 909, 134–138 (2018).
[4] R. Pompili et al., Phys. Rev. Accel. Beams, 22:121302, Dec 2019.

Speaker: Enrica Chiadroni (Sapienza University of Rome)

TUP3019_edited_version.pdf

16:00 Breakthroughs in EuPRAXIA-DN on the path to next-generation plasma accelerators

The EuPRAXIA Doctoral Network (EuPRAXIA-DN) has delivered major advances over the past year in laser–plasma physics, beam diagnostics, and compact radiation-source concepts. Experiments demonstrated superradiant nonlinear Thomson scattering, showing collective enhancement of radiation from relativistic electron bunches interacting with azimuthally polarized laser pulses. Diagnostics developments include new methods to retrieve femtosecond longitudinal bunch profiles from coherent THz transition-radiation images, as well as preliminary shot-to-shot charge measurements in high-EMP environments using diamond detectors, supported by high-precision characterization of the detector.

This poster presents these important results in the context of the broader EuPRAXIA-DN project. It highlights how coordinated R&D, structured training, cross-sector international secondments, EuPRAXIA Schools and Camps, as well as hands-on training at world-class research facilities accelerate the technological progress and talent pipeline required for compact, user-ready plasma accelerators.

Speaker: Prof. Carsten Welsch (Cockcroft Institute, Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati)

TUP3060_edited_version.pdf

16:00 Building a MOPA laser for H- beam shaping

We present the design and initial amplification stages of a seeded Master Oscillator Power Amplifier (MOPA) laser for H- beam shaping applications. Customizable modulation of the input (seed) laser pulse shape will be shown to optimize the amplified laser pulse shape output at the nanosecond level, allowing for high speed ‘notching’ or ‘trimming’ of photo-ionized H- bunch shapes. By matching the laser pulse train shape to the inverse of the desired H- bunch shape, the design of our laser system will be theoretically applied to the selective longitudinal neutralization of low energy (1 MeV) H- beams. Theoretically needed pulse energies for high percentage photo-ionizations above 99.9% will be presented and challenges for reaching the required laser pulse energies and repetition rates will be discussed. Finally, we will examine the potential for using these custom laser pulse trains to trim residual tails the H- beam through complex laser pulse shape and multiple laser – bunch interactions in a specially designed high reflectively laser cavity, reducing the total power required to reach high neutralization efficiency.

Speaker: Charles Rohde (Los Alamos National Laboratory)

TUP7364_edited_version.pdf

16:00 Capturing Beam from Two Different Linear Accelerators in the Canadian Light Source Booster Synchrotron

The Canadian Light Source recently replaced its aging linear accelerator (linac) with one procured from Research Instruments GmbH (RI). The original linac operated at a frequency of 2856 MHz, which is not a harmonic of the 500 MHz booster ring rf. The two rf systems were not synchronized and the linac beam was rebunched into the booster rf buckets, causing losses of at least 33% at injection. The RI linac is synchronized to the booster ring rf frequency through the 500 MHz pulsed gun and sub-harmonic pre-buncher. The RI linac S-band rf is also synchronized and operates at approximately 3.0 GHz, the sixth harmonic of the booster ring rf frequency.

In this report, we compare observations made while capturing the beams from these two linacs with different rf frequencies.

Speaker: Ward Wurtz (Canadian Light Source (Canada))

TUP2354_edited_version.pdf

16:00 Cavity optimizations and beam dynamics simulations for LANSCE upgrades

Distributed drive linear accelerators (DDLs), in which each accelerating cell is independently powered, offer the flexibility to set the phase and amplitude of the RF fields in each cavity individually. In the limiting case of a linac composed entirely of independently-driven single-cell cavities, the RF power required per individual cavity can be a good match to the capabilities of solid-state amplifiers. For these reasons, the possibility of upgrading the current coupled cavity linac (CCL) in the LANSCE accelerator at Los Alamos National Laboratory to a DDL architecture is being investigated. Here we report results from cell profile optimizations and beam dynamics simulations carried out to study the potential advantages of a DDL architecture in the LANSCE accelerator.

Speaker: Michael Kaemingk (Los Alamos National Laboratory)

TUP7317_edited_version.pdf

16:00 Ceramic Enhanced Accelerating Structure (CEAS) optimization for improved shunt impedance

We present a COMSOL Multiphysics®–based workflow, using the Optimization Module, to increase RF cavity shunt impedance (Rsh) by systematically reshaping the nose cones. The cavity being optimized is utilizing the Ceramic Enhanced Accelerating Structure (CEAS) approach with a ceramic tube insert at the inner electric field zero of the TM020 mode, which increases the efficiency by reducing power dissipation. The CEAS concept, combined with the improved shunt impedance from nose cone optimization, yields a particularly efficient cavity. The cavity is parameterized with smooth geometric variables (nose tip radius, cone angle, gap, fillets). This optimization maximizes Rsh subject to frequency locking and engineering limits based on the cavity geometry. Eigen-frequency studies are used as the primary optimization tool producing a field map of the desired TM020 mode as well as the power dissipated on the walls and within the ceramic material. Post processing optimization computes Rsh and peak nose cone field from the electric field profile and losses. Single cell studies show higher Rsh without degrading cavity performance; optimal profiles provide moderating curvature to control local field enhancement.

Speaker: Dr John Lewellen (Los Alamos National Laboratory)

TUP7318_edited_version.pdf

16:00 CERN Innovation Programme on Environmental Applications (CIPEA): leveraging accelerator technologies for environmental impact

The CERN Innovation Programme on Environmental Applications (CIPEA) was launched in 2022 as a call for ideas to stimulate novel environmental applications based on CERN’s technologies, scientific expertise and unique research infrastructure. CIPEA has since evolved into an integrated framework encompassing many CERN initiatives aimed at generating environmental impact beyond the Organization’s own operational footprint. More than 25 projects are currently being developed with external partners, primarily from industry, drawing on competences integral to accelerator science, including superconductivity, high-field magnets, materials, cryogenics, vacuum systems, radiofrequency technologies, cooling and ventilation, and laser beams. Activities are structured around four key application areas: renewable and low-carbon energy; clean transportation and future mobility; climate-change mitigation and pollution control; and sustainability and green science. CIPEA is largely externally funded, with over 80% of its resources contributed by partner organizations.
This paper outlines the programme’s overall strategy, describes the priority development axes within each application area, provides an overview of ongoing efforts and highlights selected flagship projects that exemplify CIPEA’s innovation potential.

Speaker: Enrico Chesta (European Organization for Nuclear Research)

16:00 Challenges of moderate energy external injection into Laser-driven Wakefield Accelerators

Laser Wakefield Acceleration (LWFA) enables GV/m acceleration gradients, promising compact accelerator designs with advantages in cost, environmental impact and portability. Standard LWFA schemes can suffer from poor shot-to-shot stability and beam quality, resulting in broad energy spectrums, beam current variations, high emittance and limited intensity. External injection schemes attempt to overcome such challenges by treating the LWFA stage as purely an accelerating structure and not as a source. Motivated by the pursuit of compactness, external injection of moderate-energy (< 60 MeV) electron beams into plasma will be explored using the Fourier-Bessel Particle-In-Cell (FBPIC) code. The sensitivity of the final beam quality to sub-optimal injection parameters will be explored. Bayesian optimisation is employed to assess whether sub-optimal injection parameters can be compensated for with laser and plasma parameters. This investigation presents working points from which future compact external injection designs can be optimised.

Speaker: Mr Jordan Byrne (University of Manchester, Cockcroft Institute)

16:00 Characterization and alignement of LINAC magnets for ELI-GBS facility

The ELI-GBS LINAC, designed to accelerate electrons up to 800 MeV, employs 23 quadrupole and 2 dipole magnets for beam focusing, steering and bending toward two diagnostic lines. Factory and laboratory measurements confirmed that both magnet types meet design specifications, with quadrupoles achieving high field homogeneity and dipoles exceeding integrated bending field requirements while maintaining uniformity within plus or minus 10^-3. Comparative tests highlighted minor differences due to measurement methodology but validated operational performance. Following delivery, the magnets were installed in the LINAC lattice with alignment corrections applied to ensure beam optics stability at the target energy. Complementary magnetostatic simulation provided a consistent model of the dipole geometry and excitation, demonstrating the integration of experimental and computational approaches for magnet characterization and installation verification in support of reliable accelerator operation.

Speaker: Cornel Dinu Cirdei (Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering, Universitatea Națională de Știință și Tehnologie Politehnica București)

TUP7012_edited_version.pdf

16:00 Characterization of RF breakdown dynamics in a C-band distributed-coupling structure

Increasing accelerating gradients of accelerating structures promises higher particle energies, while reducing the total footprint and cost. Characterizing RF breakdown effects is crucial when pushing to higher gradients, as RF breakdown changes the reflected and transmitted power flow in traditional accelerators and can cause loss of operation and surface damage. In this work, we study low power RF cavity response in air under an induced arc to gain insight into RF breakdown dynamics. Arcs were triggered to study how RF breakdown in an upstream cavity affects the adjacent cavity for a distributed coupling structure. The test structure consists of two C-band cavities connected to a hybrid coupler with a high voltage (HV) probe inserted into the beampipe of the upstream cavity. Pulsed RF is fed into the hybrid, and an arc is triggered in the upstream cavity via HV pulses fed into the probe. A directional coupler allows forward and reflected measurements going in and out of the hybrid while a field probe coupled to the output load is also measured. Initial results show that the rf signals remain unaffected by the breakdown in upstream cavity, suggesting that RF breakdown effects in distributed coupling structures are localized and do not perturb the electrodynamics of the downstream cavities. Experiments under vacuum and nitrogen are planned and modeling is underway. Results from this study will be used for informed design of new accelerating structures.

Speaker: Sophia Morton (SLAC National Accelerator Laboratory)

16:00 Characterization of self-modulation in a plasma wakefield accelerator

AWAKE uses a long relativistic proton bunch (400 GeV, 48 nC) to drive wakefields in plasma. The amplitude of the wakefields increases along the plasma as the bunch undergoes self-modulation (SM). Wakefields are energy deposited in the plasma that must dissipate, a fraction of which is emitted as light. We measure the amount of light emitted to study the development of the wakefield amplitude along the plasma. We present experimental results that show: growth and saturation of SM along the plasma; differences in development of SM depending on the charge of the drive bunch and the plasma density; differences when SM is seeded (SSM) or developing as an instability (SMI). These observations are also confirmed by other diagnostics. However, this is the only diagnostic with multiple measurement points along the plasma, enabling observation of the SM process as it develops.

Speakers: Jan Mezger (Max Planck Institute for Physics), Jan Mezger (Max Planck Institute for Physics)

TUP3039_edited_version.pdf

16:00 Characterization of wet-wound insulated 2G-HTS tape in a dewar

The second-generation high-temperature superconductor (2G-HTS) is under consideration for accelerator applications because its operating temperature, which is higher than 4.2 K, eliminates the need for liquid helium. However, the relatively low engineering critical current, inter-layer insulation challenges, welding reliability and quench protection remain key technical issues. In this work, an insulated 2G-HTS tape was wet-wound using a low-temperature adhesive. The winding method, charging behavior, as well as quench protection were experimentally investigated. A simple liquid-helium-free test dewar is also presented.

Speaker: Chin-Kang Yang (National Synchrotron Radiation Research Center)

TUP7661_edited_version.pdf

16:00 CLS: return to operation

In 2024, the CLS linac injector was removed and exchanged with a newer more compact injector capable of 10 Hz operation and producing an electron beam of 250 MeV. Unfortunately the commissioning did not go as planned and the facility stayed dark 1 year longer than planned. We are summarizing what it took to provide beam to our users and the plan to remediate to the existing deficiencies and the risk associated to them.

Speaker: Frédéric Le Pimpec (Canadian Light Source (Canada))

TUP2306_edited_version.pdf

16:00 Commercial Accelerators for Proton Therapy - An Overview

There are different accelerator types used for proton therapy of diverse tumours. In use are mostly classical cyclotrons, synchrocyclotrons and synchrotrons. In addition, linear accelerators were or are under development. This paper will give an overview on commercially available systems. Not only technical aspects are discussed, but also new developments in treatment methods like ARC and FLASH therapy as well as irradiations in upright position and the backlash on the used accelerator types. Furthermore practical issues like certification and embedding those systems in a hospital environment will be described and evaluated.

Speaker: Andreas Peters (Heidelberg Ionenstrahl-Therapie Centrum)

TUV8001_edited_version.pdf

16:00 Commisioning of a new beamline for medical research and radiation hardness testing

The HZB cyclotron accelerator complex provides 68 MeV protons for therapy and related research. The main accelerator is an isochronous sector cyclotron served by two injectors.
The treatment room is fixed according to the regulatory agencies and the adjoining experimental station is often overbooked with users for radiation hardness test and dosimetry. To widen the irradiation possibilities, we built up a new beamline for medical research with minibeams and a second target station is prepared for radiation hardness experiments.
The setup, possibilities and commissioning for these stations will be presented.

Speaker: Jürgen Bundesmann (Helmholtz-Zentrum Berlin für Materialien und Energie)

TUP8007_edited_version.pdf

16:00 Commissioning and current status of High Energy Photon Source

High Energy Photon Source (HEPS) is a 4th generation synchrotron radiation facility built in Beijng, China. The designed electron energy of HEPS is 6GeV and the emmitance is lower than 0.1nmrad. This machine can provide the hard X-ray with brilliance higher than 1022ph/s/mm2/mrad2/0.1%BW and photon energy higher than 300keV.
The construction of HEPS started in June 2019, including a 500MeV LINAC, a 6GeV booster, a 1360m-circunference storage ring, 14 public beamlines and 1 test optical beamline, as well as the auxiliary facilities and building.
The installation of storage ring started in February 2023. In July 23, 2024, we started the commissioning of storage ring. Now the beam current can reach to 100mA and the emmitance was 56.8pmrad. The first synchrotron light from insertion device was firstly obtained in October 12, 2024.
During the installation of storage ring, the front-ends of beamlines were installed in Oct. 21, 2022. The first monochromator was installed in Dec. 15, 2023. The commissioning of beamlines was started in Sep. 2024.
In Oct. 29, 2025, HEPS passed the performance acceptance organized by the Chinese Academy of Sciences. HEPS is now poised to serve as a premier platform for original and innovative research across basic and engineering sciences and will open to global users in 2026.

Speaker: Yuhui Dong (Institute of High Energy Physics, Chinese Academy of Sciences)

16:00 Commissioning and initial operation of a Compact FEL-THz facility at IUAC, New Delhi

A compact THz facility, based on Free Electron Laser (FEL) system has been commissioned at Inter University Accelerator Centre (IUAC), New Delhi. The design of the facility is based on pre-bunched FEL where a train of electron micro-bunches having maximum energy of 8 MeV are intended to be injected into a short undulator to produce the THz radiation in the range of 0.18 - 3.0 THz. The electron micro bunches are produced from the photocathode by striking with the ultra-short laser pulses generated from an advanced Fibre laser system. The frequency of THz can be tuned by varying the separation of the laser micro-pulses which produce the electron micro-bunches with variable separation. The electron micro-bunches are being injected in to the undulator to produce the THz radiation and the electron beam along with the THz radiation are co-propagating through the undulator. At the exit of the undulator, a thin Titanium foil is kept through which the electron beam passes through and the THz radiation gets reflected, subsequently detected by the Schottky Barrier Diode detector. The commissioning details and the initial operation of the of the various sub-systems of the compact FEL-THz facility e.g. high-power RF systems, electron gun, fibre laser system, state of the art photocathode deposition system, undulator, various beam transport and beam diagnostic systems, etc. will be presented in this paper.

Speaker: Bhuban Kumar Sahu (Inter-University Accelerator Centre)

TUV2601_edited_version.pdf

16:00 Commissioning experiences of active double-RF system in HEPS storage ring

The High Energy Photon Source (HEPS) is the first fourth-generation synchrotron light source in Asia. In HEPS storage ring, there are five 166.6 MHz superconducting cavities serving as fundamental cavities and two 499.8 MHz superconducting cavities as active third harmonic cavities. The employment of active harmonic cavities enables ‘ideal bunch lengthening’ at any beam current, laying a foundation for flexible beam operation.

Beam commissioning of the HEPS storage ring started on July 23, 2024. Due to the presence of delays in the 166.6 MHz cavities, the 499.8 MHz cavities were temporarily utilized as fundamental cavities to provide the required beam acceleration for the first-year commissioning. Starting from August 2025, we initiated the commissioning of an active double-RF system composed of the 166.6 MHz and 499.8 MHz cavities, successfully realizing ideal bunch lengthening under different beam current. Since August 2025, we have commissioned the active double-RF system, successfully achieving ideal bunch lengthening under various beam current conditions.

During the ring commissioning process, some beam phenomena associated with the operation of the double-RF system were observed, and experiences in commissioning active double-RF systems was accumulated. This paper reports the key experiences gained from the commissioning and operation of the active double-RF system in the HEPS storage ring, aiming to provide references for similar accelerator projects.

Speaker: Haisheng Xu (Institute of High Energy Physics, University of Chinese Academy of Sciences)

TUP2673_edited_version.pdf

16:00 Commissioning of the ELIMED Line: challenges in the selection and extraction of a laser-driven beam

The ELIMAIA–ELIMED user beamline at ELI Beamlines provides a versatile platform for acceleration, selection, and application of laser-driven ion beams. Designed to bridge laser–plasma acceleration research with multidisciplinary applications, it combines the L3 Petawatt laser with a particle beam transport, diagnostic, and dosimetry system named ELIMED.
In this contribution, we present the main characteristics and capabilities of the ELIMED ion beam transport system. We also describe the initial phases of the experimental testing, highlighting key results, challenges encountered, and the solutions adopted.In particular, we report on the successful extraction of a selected ion beam with a central energy of 20 MeV with a 30% energy spread at FWHM, i.e. a spread ranging from 17 to 23 MeV, corresponding to a 7nsec bunch length at the sample location (7.5m downstream the interaction point). The achieved peak dose was of about 40mGy per laser shot which, with a 7nsec long bunch delivered to the irradiation point and successfully used for irradiation experiments of biological samples, both cells and embryos, as part of the ELI User Program.
These preliminary steps were crucial for enhancing the beam diagnostics along the line, improving control over beam transport, energy selection, and final beam shaping, with the goal to offer a more reliable machine to the users from different communities.

Speaker: Francesco Schillaci (ELI Beamlines Czech Republic)

16:00 Commissioning of the injector system for the X-band electron linear accelerator in Melbourne

The University of Melbourne’s X-band Laboratory for Accelerators and Beams (X-LAB) is developing a compact electron linear accelerator. The injector system will consist of a 100 keV DC photogun, a pulsed UV laser, an S-band (2.9985 GHz) RF buncher, and magnetic elements for beam transport. This paper reports on the commissioning of the injector system. We present the characterisation of the test laser and buncher, as well as initial electron beam measurements with Faraday cup. Particle tracking simulations using General Particle Tracer (GPT) code were used to obtain approximate optimal solenoid currents. We also report on the conditioning of the photogun, including photocathode inspection, vacuum performance, dark current, and stray radiation.

Speaker: Joel Valerian (The University of Melbourne)

TUP2695_edited_version.pdf

16:00 Commissioning status of booster-based beam-recycling swap-out injection at HEPS

The High Energy Photon Source (HEPS) adopts on-axis
swap-out injection to relax the dynamic-aperture requirement of its ultralow-emittance storage ring. To provide
high-charge bunches for swap-out operation, a booster-based
beam-recycling scheme has been developed, in which a depleted storage-ring bunch is extracted, transported to the
booster, combined with a newly accelerated bunch at high
energy, damped, and reinjected into the original storagering bucket. This paper summarizes the commissioning
status of this scheme. Closed-loop beam recycling has been
demonstrated, paving the way for user operation toward high
bunch charge. The results validate the basic beam-recycling
architecture and identify the main directions for further optimization toward routine high-charge operation.

Speaker: Zhe Duan (Institute of High Energy Physics)

TUP2703_edited_version.pdf

16:00 Commissionning progress of SHINE LINAC

The SHINE Linac consists of fifty-four 1.3GHz cryomodules and two 3.9GHz cryomudules, which can provide 8GeV high-repetition rate electron bunches. The commissioning of the first Linac section (L1) was carried out from August to November 2025. In this work, We present an overview of the commissioning results, including the achieved beam parameters, machine optimization strategy, injector operation status and main challenges . Also, the commissioning plan for the rest part of Linac will be given.

Speaker: Duan Gu (Shanghai Advanced Research Institute)

16:00 Compact Multi-Mode RF Loads for high-peak and high-average power applications

We present an all-metal RF load that uses a series of mode conversions within an overmoded planar waveguide to extend the device's effective electric length. We present devices with two, three, and four modes operating simultaneously to achieve uniform power absorption across the broad side of the planar waveguide. The guide is made of highly conducting material, copper or aluminum, with a few microns of 430 Stainless steel sputtered on its surface. The properties of this magnetic stainless steel were carefully characterized using special TE01 resonant cavities. In one incarnation of the device, the overall dimensions are relatively small, only 5 to 6 wavelengths in two dimensions, and about 2 wavelengths in the third. H-fields were calculated as point clouds for a 6 kW average power heat load. The H-field point clouds were converted to spatially dependent heat flux values and applied to the vacuum cavity walls. A cooling channel and manifold design is presented along with the full manufacturing ready prototype design.

Speaker: Sami Tantawi (Arizona State University)

16:00 Compact X-Band Linear Accelerators Design for On-Site Industrial Applications

The progressive replacement of radioactive sources is stimulating growing interest in compact linear accelerators, which are better suited for field deployment. Such systems must emphasize modularity, transportability, and, above all, reliable performance under operational conditions.

This work introduces a family of compact X-band linear accelerators designed to produce electron beams in the low-MeV energy. The engineering design focuses on the key component: the accelerator structure. A biperiodic on-axis coupled standing-wave structure was selected, operating in $\pi/2$ mode.

Simulation results demonstrate that the proposed configurations achieve the targeted energy levels with controlled beam transmission, while providing a focal spot size (FWHM) below 1 mm, significantly outperforming conventional radioactive sources ($\approx 5$ mm).

This paper summarizes the overall design approach, highlights the main simulation results, and outlines the current progress of development activities.

Speaker: Manon Boucard (AVELION)

TUP8002_edited_version.pdf

16:00 Consideration of an unbunched high energy electron storage ring

Electron storage ring light sources rely exclusively on RF cavities to restore energy to the beam that is lost to photon emission. A limitation of RF is that it can store particles in only a small region of the RF waveform, yielding a bunched beam. Only a few percent of the ring circumference actually contains charge. Thus, high average current entails high peak current. While high average current and low emittance are the target parameters of the light source, the limitations come from peak current effects.

With recent advances, induction cells are potential replacements for RF cavities. The cells are compact, and a small number of them could be orchestrated to provide DC, or nearly DC, restoring voltage, yielding a continuous, unbunched beam.

SLAC is investigating the physics of continuous beam induction storage rings. Potential applications include continuous beam light sources with smaller emittances and higher currents, and also coherent emission light sources utilizing steady state microbunching (SSMB). For applications including SSMB, we are also investigating isochronous rings based on anti-bend cell acromats.

Speaker: Michael Ehrlichman (SLAC National Accelerator Laboratory)

16:00 Construction of Permanent Magnet Arrays without Custom Materials

Permanent magnet Halbach arrays can be used for beam steering and focusing for synchrotron light sources, Fixed Field Accelerators, and plasma accelerators. Conventional implementations require many custom wedge-shaped magnets with tailored geometries and magnetisation angles, preventing material reuse. We present a method for constructing Halbach arrays from many identical rectangular magnets, each rotated in the transverse plane to approximate the optimal configuration. Although this introduces gaps and reduces magnetic efficiency compared with custom-wedge designs, it simplifies fabrication, lowers costs, and enables the magnets to be redeployed for future applications. A prototype array based on this approach has been built for Project TURBO at the University of Melbourne, and measurements confirm that the magnetic field quality meets the requirements of the planned beamline. Construction of the full arrays for TURBO will soon commence, and the reusability of the magnets is expected to provide long term flexibility for subsequent accelerator projects.

Speaker: Adam Steinberg (The University of Melbourne)

TUP7723_edited_version.pdf

16:00 Continuous THz Band Coverage through Precise Electron Beam Tailoring in Free-electron Lasers

High-power, continuously tunable narrowband terahertz (THz) sources are essential for advancing nonlinear optics, THz-driven material dynamics, and ultrafast spectroscopy. Conventional techniques typically impose a trade-off between pulse energy and frequency tunability. Here, we demonstrate a novel free-electron laser approach that overcomes these limitations by pre-modulating a relativistic electron beam with a frequency-beating laser pulse and leveraging bunch compression along with collective effects to enhance microbunching. Experimental results demonstrate that this technique generates narrowband THz emission with continuous frequency tunability from 7.8 to 30.8 THz, achieving pulse energies up to 385 μJ while maintaining spectral bandwidths between 7.7% and 14.7%. Moreover, the method exhibits exceptional robustness and scalability, highlighting its unique ability to bridge the long-standing THz gap and offering a promising solution for diverse cutting-edge scientific applications.

Speaker: Yin Kang (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

16:00 Conversion of 28 MHz Cavities to 24.6 MHz Cavities for the EIC Hadron Storage Ring

In the Electron–Ion Collider (EIC), we plan to use 24.6 MHz normal-conducting cavities to provide 600 kV in the Hadron Storage Ring (HSR) for beam capture, acceleration, and transition crossing. The existing four 28 MHz cavities have been operating in RHIC for more than twenty years. To reduce costs, we will reuse their large outer conductor, power amplifier, and associated components for the 24.6 MHz system. We designed new inner conductors, HOM dampers, and increased the number of ferrite fast tuners to four. The cavity parameters of the fundamental mode at 24.631 MHz have been optimized. Two mechanical tuners provide a tuning range from −160 kHz to +40 kHz relative to the nominal 24.631 MHz. The four fast ferrite tuners enable approximately 20 kHz of tuning on the millisecond timescale. The HOM impedances are optimized to remain within the beamline impedance budget. The HOM power was calculated considering various hadron beam parameters—including ion species, charge, and bunch number—and the worst-case power absorbed by the HOM dampers was further evaluated. Frequency shifts arising from fabrication tolerances were estimated and will be compensated during final tuning. Multiphysics simulations were performed to analyze RF-induced thermal distributions and the water-cooling circuits.

Speakers: Guangjiang Li (Brookhaven National Laboratory), Silvia Verdu-Andres (Brookhaven National Laboratory)

TUP7309_edited_version.pdf

16:00 Coupled-bunch instability study for UTEF storage ring

The Ultra-fast Transient Experimental Facility (UTEF) at Chongqing University is currently constructing a 500MeV storage ring. This paper investigates the transverse coupled-bunch instabilities (TCBI) critical to its high-current operation. Building on a method previously developed at Diamond Light Source—which enables the calculation of all coupled-bunch instability modes within a single simulation—this work extends the approach to non-zero chromaticity cases using a multi-particle-per-bunch model. Results for the UTEF ring demonstrate that non-zero chromaticity and synchrotron radiation damping have a negligible impact on the grow-damp curve. On the other hand, the inclusion of short-range impedance brings an obvious shift of the grow-damp curve. This paper provides a detailed account of the simulation and results.

Speaker: Jincheng Xiao (University of Science and Technology of China)

TUP2618_edited_version.pdf

16:00 cSTART – Status on the compact electron STorage ring for non-equilibrium Accelerator Research and Technology

The goals of the cSTART storage ring at Karlsruhe Institute of Technology (KIT) are to demonstrate the storage of ultra-short electron bunches and study their non-equilibrium dynamics. Furthermore, it aims to study the application of laser-plasma accelerators (LPAs) as injectors for storage rings. To allow the direct injection of LPA bunches with comparably large energy spread, cSTART has a specifically designed flexible magnetic lattice with large momentum acceptance. The non-ramping ring will also use the existing linac-based accelerator FLUTE as injector for commissioning and experiments with controlled beam parameters.

In 2024, the collaboration between KIT, RI Research Instruments GmbH, and its subcontractors completed the Technical Design Report (TDR), followed by the Final Design Report (FDR) in spring 2026. The magnets and power supplies for the injection line (IL), which will connect FLUTE to the storgae ring, are already available in KIT’s inventory. Meanwhile, the magnets, power supplies, and vacuum chambers for the storgae ring are currently in production. This contribution provides an overview of the current status an outlines the next steps of the cSTART project.

Speaker: Robert Ruprecht (Karlsruhe Institute of Technology)

16:00 Current status of the upgrade and operation of the NSRRC TPS linac pulse high-power RF System

The NSRRC Taiwan Photon Source (TPS) LINAC system consists of a DC thermionic electron gun, a Sub-Harmonic Pre-Buncher, a Primary Buncher, a Final Buncher, three S-band LINAC sections, and three 35-MW S-band klystrons. The TPS LINAC was designed by Research Instruments (RI). In the original design, the S-band klystrons were Thales TH2100A tubes. Due to unstable production quality in recent years and the resulting reduction in tube lifetime, NSRRC initiated a klystron upgrade program to replace the TH2100A with the E37310A klystron manufactured by CETD.
The primary objective of this work is to analyze the RI-designed LINAC system and complete the necessary modification design so that it can operate with the CETD E37310A klystron and supply the required RF power. Leveraging the technology and experience gained from the in-house development of the THz FEL pulse RF system, NSRRC successfully upgraded the Taiwan Light Source LINAC pulse RF system in August 2023. After six months of stable operation, planning for upgrading the three TPS LINAC pulse RF systems began in 2024. Compared with the TLS system, the RI turnkey LINAC is more complex and requires additional study to support an in-house upgrade.
This paper presents the upgrade work and results of the first and second TPS LINAC pulse RF systems completed in September 2025 and January 2026, including system installation, modulator modification design, testing results, and current operational status.

Speaker: Dr Wei-Yuan Chiang (National Synchrotron Radiation Research Center)

TUP7647_edited_version.pdf

16:00 Current status of TPS vacuum system

The TPS is currently operating at a beam current of 500 mA for users. Until now, 17 insertion devices have been installed in the straight vacuum sections, and the associated vacuum components have been upgraded. The average vacuum pressure of the storage ring is 8.5 nPa, and the beam lifetime under 500 mA operation is approximately 6 hours. The behavior of vacuum readings, the pressure distribution and the related interlock will be discussed in this paper.

Speaker: Yi-Chen Yang (National Synchrotron Radiation Research Center)

TUP7693_edited_version.pdf

16:00 CW positron beam capture scheme using SRF cavities

A continuous wave (CW) positron source, as proposed Ce+baf at Jlab, produces positron beams of variable yield and polarization. Depending on users’ preferences, the Ce+baf positrons from the target needs to be selected and captured before being delivered to CEBAF linac at an energy of 123 MeV. An SRF cavity-solenoid capture scheme is proposed to accelerate and capture the CW positron beam using adiabatic damping and profile control to maximize transmission into the CEBAF acceptance. Beam particle and power loss throughout the capture section are analyzed. The initial beamline design of SRF cavities and solenoids in a cryomodule is performed to examine the influence of solenoid’s magnetic field on the SRF cavity operation. The application of SRF cavities with larger iris radius to the capture section is also studied in efforts to improve the capture efficiency.

Speaker: Salim Ogur (Thomas Jefferson National Accelerator Facility)

TUP3303_edited_version.pdf

16:00 Data-Driven Multi-Objective Optimization for Attosecond XFEL Design

In the design of high-power attosecond X-ray free-electron laser (XFEL) pulses, strongly coupled collective effects and many tunable parameters turn layout and parameter choice into a challenging multi-objective optimization issue. Conventional evolutionary approaches such as NSGA-II and NSGA-III require a very large number of high-fidelity start-to-end simulations, which makes systematic optimization prohibitively expensive for state-of-the-art XFEL facilities. We propose a data-driven surrogate framework for high-dimensional multi-objective optimization in this setting. A machine-learning surrogate model is trained on a limited set of high-fidelity simulations and then replaces most simulation calls in the optimization loop. As a first application, we optimize the AttoSHINE scheme for the Shanghai High Repetition Rate XFEL and Extreme Light Facility (SHINE). The resulting Pareto-optimal solutions reveal non-trivial trade-offs in the AttoSHINE design and identify parameter regions that support terawatt-level attosecond pulses at greatly reduced computational cost compared with direct NSGA-II or NSGA-III optimization. The proposed framework offers an efficient and flexible route to multi-objective design of attosecond XFEL beamlines and, more broadly, complex accelerator systems.

Speaker: Chenzhi Xu (Shanghai Institute of Applied Physics)

16:00 Density downramp injection into a discharge-based plasma acceleration stage

Electron bunches internally injected into plasma accelerators reach relativistic energies in giga-volt-per-metre-level fields, reducing emittance growth due to space charge and ultimately yielding high-brightness beams.Density downramps with steep gradients have provided an effective method of controllable injection into beam-driven plasma-wakefield accelerators, but previously have relied on the fields of an intense particle beam or laser to preionise the acceleration stage. Here, injection using downramps formed via optical ionisation is experimentally shown to be compatible with discharge-based-acceleration stages, producing bunches with up to six times higher energy than with laser-only preionisation. Results demonstrating injection of charge using a purely discharge-preionised acceleration stage and a low-energy injection laser suggest the feasibility of a scalable, high-repetition-rate injection stage—potentially attractive for high-average-power applications.

Speaker: Lewis Boulton (Deutsches Elektronen-Synchrotron DESY)

TUP3041_edited_version.pdf

16:00 Design a fast kicker for SPEAR3 pseudo single bunch operation

Stripline kickers are widely used in particle accelerators. This paper presents the design of a fast stripline kicker operating at 1.28 MHz to enable pseudo-single-bunch mode in SPEAR3. The combination of the required kick strength and the high repetition rate creates significant challenges, primarily beam-induced heating of the kicker structure. The physics and mechanical designs were optimized to mitigate these effects. The design approach and key performance considerations are discussed.

Speaker: Kai Tian (SLAC National Accelerator Laboratory)

TUP2311_edited_version.pdf

16:00 Design and construction of a HOM-damped TM020 type harmonic cavity for luminosity enhancement in RI-electron scattering

The RIKEN SCRIT facility that involves an electron storage ring (SR2) is a dedicated RI-electron scattering experiment. In the SCRIT system, the target RI ions are confined at high density on the beam axis by the focusing force provided by the electron beam itself. Therefore, electron beam stability is essential to increase the luminosity and maintain it for a sufficient time during scattering experiments. Since the current RF cavity induces beam instabilities due to higher order modes (HOM), a new HOM damped cavity is being designed and constructed and will soon be replaced. Here, we adopted the TM020 type harmonic cavity, which has recently been developed and first practically used at the NanoTerasu synchrotron light source. The cavity has coaxial slots at both the front and rear ends with ferrite absorbers inside. It is a very simple and compact design, yet it efficiently damps most resonant modes except for the TM020 mode. The design frequency of the TM020 is 956.220 MHz, which is the fifth harmonic of the current drive frequency 191.244 MHz, and accordingly the harmonic number in SR2 is changed from 14 to 70. As revealing from simulation studies, an increase in the harmonic number makes the trapping lifetime of the target RI ions longer, and this effect, coupled with the stabilization due to the disappearance of HOMs, is expected to significantly improve the luminosity performance in RI electron scattering.

Speaker: Masanori Wakasugi (Kyoto University)

TUP7626_edited_version.pdf

16:00 Design and construction of the twin-aperture superconducting quadrupole full-size prototype for the STFC IRSM

Super Tau Charm Facility (STCF) is the third-generation e+-e- collider under design and R&D with a circumference of about 800-900 m, a center-of-mass energy range from 2-7 GeV and design luminosity higher than 0.5 x 1035 cm-2 s-1, about 100 times higher than BEPC-II. To squeeze the beam for higher luminosity, compact twin-aperture high gradient interaction region superconducting magnet (IRSM) systems are required on both sides of interaction point (IP). The IRSM system consists of four twin-aperture superconducting quadrupole magnets. As part of the key R&D activities at accelerator CDR stage, full-scale twin-aperture QD1 quadrupole magnets were designed and constructed. The QD1 magnets have design field gradients of 50 T/m, field harmonics below 0.2‰, and site at 900 mm distance away from IP at beam crossing angle of 60 mrad. In this paper, details of QD1 design, construction and test are reported.

Speaker: Wenbin Ma (High Magnetic Field Laboratory, Hefei Institutes of Physical Science, Chinese Academy of Sciences)

TUP7657_edited_version.pdf

16:00 Design and experiment of energy feedback unit for 15 kV/15 kA AMD excitation pulse source

Abstract:
The Super Taume-Charm Facility (STCF), a new generation of electron-positron collider led by the University of Science and Technology of China, requires a high-quality positron source to sustain high-luminosity continuous operation. The Adiabatic Matching Device (AMD) is a critical component for positron focusing, its excitation pulse source requires a peak current ≥15 kA and a pulse front edge ≤3.5 us. To reduce the significant power dissipation of pulse discharge system, an energy feedback circuit was designed. The optimized system achieved a dramatic reduction in losses, decreasing input power by 73.96% and enhancing long-term operational stability. This article provides a detailed account of the simulation of power loss in AMD excitation pulse sources, as well as the design, simulation, and offline debugging of energy feedback circuits.

Key words: excitation pulse power for AMD; power loss; energy feedback; photoconductive semiconductor switch

Speaker: Zichen Zhong (University of Science and Technology of China)

TUP7709_edited_version.pdf

16:00 Design and implementation of ridge waveguides for dual-mode microwave structure

The dual-mode microwave structure is receiving increasing attention and research. In the application of dual-mode structures, it is necessary to solve the problem feeding microwave power at different frequencies. One method is to use complex waveguide components, such as first and second harmonic photocathode bimodal gun, which consists of the assembly of the directional coupler and the mode launcher. The structure combines the S-band and C-band power into a waveguide and feeds them into the dual-mode electronic gun. Another method is to use ridge waveguide to achieve selectable transmission or blocking of specific frequency. Currently, the ridge waveguide has been applied to dual-mode deflecting structure. This paper presents a X-band bandpass filter has been engineered to achieve a power reflection level of less than -30 dB at 12 GHz and a power transmission level of less than -40 dB at 24 GHz.

Speaker: Xiaoxia Huang (Shanghai Synchrotron Radiation Facility)

TUP7623_edited_version.pdf

16:00 Design and Integration of ALS-U Storage Ring Modules

The Advanced Light Source Upgrade (ALS-U) is an ongoing project at Berkeley Lab to transform the ALS into a fourth-generation synchrotron light source. To minimize the ALS users facility down time, the ALS-U Storage Ring (SR) is composed of 48 unique, highly integrated modules, each split into approximately 11 subsystems. There are over 3000 unique physical interfaces across the system, with 27 interface pairs internal to the module, as well as externally between modules, facilities and beamlines. This contribution presents how the complex interfaces have been managed using interface control documentation and tailored interface verification methods based on a combination of Computer-Aided Design (CAD) assemblies and dedicated prototypes. These tools were adopted to manage both module-level integration and external interfaces with facility infrastructure and beamlines to mitigate integration risks. To validate the design solutions a physical 1:1 mock-up has been developed alongside the CAD models. The combined CAD-mockup validation approach revealed critical issues not detectable through CAD only, including cables’ installation feasibility problems that would have caused redesign work and significant delays. The physical mockup also enabled more accurate analysis of maintenance access, assembly process and electrical safety. The practical experience from SR modules design in facility/beamlines integration context, methodology evolution during the design process, and recommendations for similar accelerator upgrade projects are also presented.

Speaker: Dmitry Gudkov (Lawrence Berkeley National Laboratory)

TUP2343_edited_version.pdf

16:00 Design and magnetic measurement results of the HALF storage ring magnets

The Hefei Advanced Light Facility (HALF) is a fourth generation synchrotron light source under construction, centered on a 2.2 GeV diffraction limited storage ring (DLSR) with a design natural emittance below 86 pm·rad. The storage ring has a circumference of nearly 480 m and contains 880 magnets in 20 lattice cells, including longitudinal gradient bends (LGB), reverse bends (RB), quadrupoles (Q), sextupoles (S), octupoles (O), and all corrector magnets (CR). As of early 2026, all magnet types except the octupoles had completed series production and factory magnetic measurements. This paper presents the physical design methodology and key magnetic measurement results of the HALF storage ring magnets, and also outlines ongoing studies on Preisach hysteresis modeling and on magnetic crosstalk in selected compact magnet assemblies through three dimensional simulations and stretched wire measurements.

Speaker: BaoHou Liu (University of Science and Technology of China)

TUP2620_edited_version.pdf

16:00 Design and Optimizations of a 1.5GHz-Superconducting-cavity cryostat

A 3rd harmonic superconducting (SC) cavity working at 1.5 GHz is required to improve beam lifetime and provide Landau damping by lengthening the bunch without energy spread for storage ring of Hefei Advanced Light Facility(HALF). The cryostat, which is used to create a liquid helium temperature environment for the SC cavity, is a key device for stable operation of this SC cavity. This paper presents design of a cryostat for such a SC cavity in detail including mechanical design and thermal analysis. Through optimizations, the calculated heat load is less than 15 W at the operation temperature of 4.5 K.

Speaker: Yelong Wei (University of Science and Technology of China)

16:00 Design and Prototype Tests of Pulsed Magnets for Beam Injection and Extraction in Korea-4GSR Project

The Korea-4GSR project is a 4-GeV diffraction-limited storage ring characterized by an ultra-low emittance of 60 pm and a stored beam current of up to 400 mA. The electron beam is accelerated to 200 MeV by a linear accelerator and further to 4 GeV by a booster synchrotron before top-up injection into the storage ring. This paper presents the specifications of the kickers and septa required for beam injection and extraction at each acceleration stage, along with the corresponding electromagnetic simulation results. In addition, experimental test results of a septum magnet prototype are presented to validate the manufacturing process and magnet performance.

Speaker: Garam Hahn (Pohang Accelerator Laboratory)

16:00 Design and Simulation of thin Eddy-current Septum for Injection of the TPS

The Taiwan Photon Source (TPS) currently utilizes a direct-drive type septum magnet for beam injection. To reduce the impact of stray magnetic fields on the stored beam during injection, we propose a conceptual design of an eddy current type septum as a replacement. This design is expected to significantly suppress leakage fields near the stored beam, thereby minimizing orbit distortion and injection-induced perturbations.
A thin eddy-current septum prototype has been developed using laminated silicon steel sheets as the magnet core. Theoretical analyses and transient field simulations have been performed using OPERA software to evaluate magnetic behavior under pulsed excitation. Due to the thin septum structure, several optimization strategies have been applied—such as shielding with strongly paramagnetic materials and excitation with a full-cycle driving pulse—to ensure the leakage field remains below 0.1% of the main field.
This paper presents the design approach, analyzes the influence of eddy currents on field distribution, and investigates compensation methods to enhance magnetic field quality and injection performance.

Speaker: Chin-Kang Yang (National Synchrotron Radiation Research Center)

TUP2706_edited_version.pdf

16:00 Design and test of an X-band cavity for short-pulse RF breakdown studies

High-gradient operation of normal-conducting radiofrequency (RF) cavities is fundamentally limited by RF breakdown, a phenomenon driven by processes including field emission, surface heating, multipacting and plasma formation. Recent studies have indicated that operating the cavities in a short-pulse regime, with RF pulses of only a few nanoseconds long, can modify the onset and dynamics of breakdown. In particular, short pulses are instrumental in limiting multipactor-driven electron growth and reducing field-emission-induced Joule heating on cavity surfaces. However, systematic experimental investigations into these dynamics are limited. We present the design of a dedicated experiment using a single-cell high-gradient X-band cavity, to be tested at the Argonne Wakefield Accelerator (AWA), for studying RF breakdown with short pulses. The experiment will employ short, adjustable RF pulses in the few-nanosecond range. We will detail the cavity design optimized for short-pulse operation, the planned operating parameter space for the measurements, and the diagnostics for time-resolved dark current and RF signals, with the ultimate goal of quantifying how breakdown behavior changes as a function of pulse length and field gradient.

Speaker: Xueying Lu (Northern Illinois University)

TUP7319_edited_version.pdf

16:00 Design and theoretical analysis of a highly compact triple-folded 20 MHz quarter-wave cavity for SSMB

To meet the energy compensation requirements of Steady-State Micro-Bunching (SSMB), a 20 MHz RF cavity with extreme axial compactness is essential. This paper presents an innovative triple-folded quarter-wave cavity design that overcomes the size limitations of conventional structures. Based on cascaded transmission line theory, we established an analytical model to optimize the cavity’s shunt impedance and tuning range. A triple-folded 20 MHz prototype was designed and validated via CST simulations, showing that the axial length is compressed to 1.25 m (approximately 1/3 the length of a standard QWC) while achieving a high shunt impedance of 558 kΩ with excellent thermal stability. This compact design offers a high-efficiency solution for low-frequency RF systems.

Speaker: Peizhi Fang (Tsinghua University)

TUP7621_edited_version.pdf

16:00 Design and vertical test of a passive 3rd harmonic superconducting cavity for HALF storage ring

A 3rd harmonic superconducting (SC) cavity is being developed for lengthening bunch and improving beam lifetime in the Hefei Advanced Light Facility (HALF) storage ring. This SC cavity is excited by an electron beam with 350 mA current, 1 nC charge, and ~6.7 ps length and requires strong damping of higher-order-modes (HOMs) in order to meet beam instability requirements. This paper presents design and vertical test of this passive 3rd harmonic SC cavity in detail. The vertical
test results indicate that the cavity accelerating voltage reaches as high as 1.5 MV with the quality factor better than 3.4E8 and there is no multipacting or field emission.

Speaker: Yelong Wei (University of Science and Technology of China)

TUP7640_edited_version.pdf

16:00 Design of 166 MHz and 500 MHz Bimodal RF Cavities Based on Coaxial Coupling

Ultra-low emittance is one of the primary directions for the development of synchrotron radiation facilities. To mitigate coupled-bunch instabilities and meet beam-lifetime requirements, higher-harmonic cavities are commonly required in diffraction-limited storage rings. Bimodal cavities are considered multifunctional and compact accelerating structures capable of integrating the functions of a fundamental RF cavity and a higher-harmonic cavity. To support the application of active bimodal RF cavities in low-energy storage-ring light sources, this paper investigates a coaxial coupling and mode-isolation scheme for bimodal cavity operation at 166 and 500 MHz.

Speaker: Dinghui Su (Shanghai Institute of Applied Physics, University of Chinese Academy of Sciences)

TUP7624_edited_version.pdf

16:00 Design of a 10-MHz high-energy-resolution light source

High energy resolution is essential for advanced spectroscopic studies of quantum materials, especially for resolving low-energy electronic features in angle-resolved photoemission spectroscopy (ARPES). However, existing light sources for ARPES still face difficulties in simultaneously providing narrow bandwidth and high photon flux. We are developing a 10-MHz coherent light source based on angular-dispersion-induced microbunching (ADM), aiming to generate narrow-band radiation with sub-meV-level energy resolution. Start-to-end simulations from the injector to the radiator have been performed to evaluate the beam dynamics and radiation performance. The simulation results show that the proposed source can provide sub-meV-level energy resolution and a photon flux above $10^{12}$ photons/s over a broad photon-energy range.

Speaker: JunHao Liu (Shanghai Advanced Research Institute)

TUP2672_edited_version.pdf

16:00 Design of a compact energy-tunable X-band linac for FLASH radiotherapy

FLASH radiotherapy (FLASH-RT) demonstrates the potential to maintain tumor control while reducing normal tissue toxicity through ultra-high dose rates. This paper presents a novel compact X-band (9.3 GHz) accelerating system designed for FLASH-RT applications. The core innovation is a dual-structure common-source architecture: the first structure provides a fixed 6 MeV energy gain, while the second enables independent continuous energy adjustment from 0 to 6 MeV via a tunable microwave network. This design allows a single klystron to drive both structures without mutual interference during energy adjustment. The system length is only approximately 1 meter. The design process integrates radio frequency (RF) simulation and beam dynamics simulation in a coupled manner, with particular focus on the bunching section optimization. This compact system provides a high-performance accelerator solution for next-generation FLASH radiotherapy, especially for intraoperative applications requiring rapid energy adjustment.

Speaker: Yusen Guo (Shanghai Synchrotron Radiation Facility)

TUP7622_edited_version.pdf

16:00 Design of a Compact Hybrid Planar Undulator

Undulators are key insertion devices in synchrotron radiation and free-electron laser (FEL) facilities, where shortening the magnetic period is a crucial technical route to achieving compact machines and short-wavelength radiation. In our previous work, we proposed and experimentally validated an ultra-compact planar undulator that provides about a 48% increase in magnetic field strength compared with a conventional planar undulator under the same period length and gap, but its field strength is fixed and not tunable, limiting its engineering applicability. Building on that work, this paper proposes a compact hybrid planar undulator design that deliberately sacrifices part of the magnetic field strength to achieve tunability over a practical working gap range. To reduce the demagnetizing field experienced by the magnets under operating conditions, permanent magnets with different grades are combined in the structure, effectively mitigating the demagnetization risk in critical regions. Using three-dimensional magnetic-field simulations and optimization, we systematically investigate the effective field, field roll-off characteristics, and integrated field errors. The results show that the proposed compact hybrid planar undulator maintains a short period and relatively high field strength while providing magnetic-field tunability, offering a useful reference for the design of next-generation compact, high-performance undulators for advanced light sources.

Speaker: Jun Wang (Shanghai Advanced Research Institute)

TUP7699_edited_version.pdf

16:00 Design of a high-repetition rate thermionic injector for SACLA upgrade

SACLA, the most compact hard-X-ray free-electron laser, has delivered user beamtime reliably for more than a decade. To satisfy growing demand, a linac upgrade is planned to reach kHz-class repetition rates with higher brightness. At the heart of this program is a new injector derived from the existing pulsed DC gun with a thermionic cathode, chosen for its proven beam quality, stability and straightforward maintenance.

Here we report a detailed beam-dynamics study of a promising injector layout. A chain of velocity-bunching sections, followed by a single magnetic chicane and strict control of emittance growth, enables up to three orders of magnitude bunch compression while keeping the emittance increase below the sub-µm level. Performance optimization employs a genetic algorithm coupled to full 3D, space-charge-dominated tracking, allowing us to identify robust operating points and tolerance windows.

The resulting working points deliver bunch lengths and emittances comparable to those from state-of-the-art injectors based on RF photocathode guns, but within a DC-gun–centric architecture.

Speaker: Vitaliy Goryashko (Uppsala University)

16:00 Design of a new booster to storage ring transfer line for nonlinear kicker injection scheme in Taiwan Photon Source

The nonlinear kicker injection scheme is a potential option for the future Taiwan Photon Source. Compared to the current four-bump injection scheme, which occupies the entire 12-meter-long straight section, the nonlinear kicker requires only a few tens of centimeters in length. A new booster-to-storage-ring transfer line has been designed to create additional space for installing more insertion devices for users. This article discusses the geometrical constraints imposed by the existing storage ring and the requirements of the injection scheme. In addition, trajectory correction and emittance measurements of the injected beam in the transfer line, as well as the injection efficiency of the nonlinear kicker, are also addressed.

Speaker: Hao-Wen Luo (National Synchrotron Radiation Research Center)

16:00 Design of a S band RF gun with heavy beam-loading for the injector of SSMB light source

Steady-State Microbunching(SSMB) light source is a highly potential new type of light source, which combines the advantages of synchrotron radiation and FEL. It possesses the characteristic of both high repeat frequency and high peak power. In order to build such a light source, we are trying to design a 20ns, 0.7A burst mode injector to produce high brightness electron beam, and we have already designed a S band RF gun for this injector.

Speaker: Zhengkai Wang (Tsinghua University)

16:00 Design of an improved S-band SLED pulse compressor

This paper presents the design of an improved SLED pulse compressor for our beam test platform at National Synchrotron Radiation Laboratory (NSRL). It consists of a 3 dB hybrid, a TE10-TE01 mode converter, and a resonator storage cavity. Through geometrical optimizations, the resonator is designed to operate in the TE0,1,10 mode, which offers a high intrinsic quality factor while maintaining cost-effectiveness. Additionally, the conventional cylindrical configuration has been modified to a double-ended conical structure, which facilitates better mode isolation.

Speaker: Yelong Wei (University of Science and Technology of China)

TUP7617_edited_version.pdf

16:00 Design of an L-band normal-conducting continuous-wave accelerating structure

To address the electron source requirements for continuous-wave (CW) MeV electron microscopes (MV EM), we developed an L-band, normal-conducting (NC), CW accelerating structure operating in π-mode. With an input radiofrequency (RF) power below 20 kW, the accelerating structure delivers GHz bunch trains, accelerating electrons from 200 keV to 1.1 MeV. Comprehensive geometry optimization, full-scale RF simulations, and beam dynamics calculations were performed to validate the design. A compact water-cooling system was integrated to mitigate thermal deformation, and its effectiveness was confirmed by detailed coupled thermal-fluid-structure simulations. This NC CW linac provides a cost-effective and highly reliable electron source solution for MV EM applications.

Speaker: Baiting Song (Tsinghua University)

16:00 Design of an X-band compact mode converter for converting TE10 mode to TE01 mode

This paper presents the design of a compact and efficient rectangular waveguide TE10 to circular waveguide TE01 mode converter operating in the X-band. By incorporating two choke slots, the design achieves a high-purity circular waveguide TE01 mode. The optimized results show that at the operating frequency of 11.424 GHz, the conversion efficiency for the circular waveguide TE01 mode is calculated to be approximately 100%, while the reflection coefficient is better than -50 dB. The bandwidth reaches more than 260 MHz for the transmission coefficient while the bandwidth is approximately 210 MHz for the reflection coefficient better than -20 dB.

Speaker: Chengzhe Wang (University of Science and Technology of China)

TUP7618_edited_version.pdf

16:00 Design of complex bend magnet for testing at NSLS-II storage ring

A novel Complex Bend (CB) magnet design has been developed at NSLS-II to support the future storage ring upgrade toward near-diffraction-limited performance. The CB concept replaces conventional dipole electromagnets with compact permanent-magnet combined-function elements, providing both strong focusing and bending within a single curved assembly. The NSLS-II upgrade will implement 120 CBs to achieve a low emittance of 15 pm·rad at 4 GeV, while preserving 8.8 m-long straight sections and reducing the ring magnet power consumption by about 70%. To further validate the CB approach as a reliable, high-performance solution for next-generation synchrotron light sources, two existing dipoles in the NSLS-II storage ring will be replaced with CBs while maintaining normal operations. The lattice design should preserve the existing tunnel geometry, minimize modifications to power supplies and optics, provide sufficient dynamic and momentum apertures for off-axis injection, and be tolerant to errors. This paper provides an overview of the design considerations for the CB installation.

Speaker: Guimei Wang (Brookhaven National Laboratory)

TUP2342_edited_version.pdf

16:00 Design of distributed pumping system using NEG strip for HALF

The design of a distributed pumping system using NEG (Non-Evaporable Getter) strips for the slender beam pipes of the Hefei Advanced Light Fa-cility (HALF) is presented. To achieve a high pumping speed and pumping capacity in a limited pumping space, a NEG strip with distributed pumping capacity was considered. A prototype of HALF vacuum cham-ber, which can be inserted into NEG strip and matched with magnet system, is designed. The activation tem-perature of NEG strip and the ultimate vacuum after activation are tested, and the results are in good agreement with those obtained from the simulation.

Speaker: Tianlong He (University of Science and Technology of China)

TUP7684_edited_version.pdf

16:00 Design of High-Field Permanent Dipole Magnet with Ultra Low Leakage Field

In the fourth-generation light sources, storage ring lattices are typically compact, potentially leading to serious cross-talk effects. Reducing the leakage field of a magnet offers an effective solution. In this paper, a novel permanent dipole magnet structure is proposed to address the magnetic flux leakage in conventional designs. Compared to traditional steel sheet shielding, this structure demonstrates superior performance in reducing leakage fields. Based on this structure, a protective permanent dipole magnet for the front end of a beamline of the Hefei Advanced Light Facility is developed and simulated using the 3D finite element method. The dipole achieves a peak field of 1.49 T with a leakage field significantly reduced to under 10 Gauss at 30 mm. This work offers a viable method to developing future permanent magnets with low magnetic cross-talk.

Speaker: Guanzheng Wu (University of Science and Technology of China)

TUP7724_edited_version.pdf

16:00 Design of photon absorbers for the SPring-8-II vacuum system

SPring-8-II, the forthcoming fourth-generation light source upgrade of SPring-8, aims to achieve X-ray brilliance approximately two orders of magnitude higher than that of the current facility by reducing the electron beam emittance to 100 pm·rad or less. To accommodate the narrow-bore five-bend lattice, the vacuum system features discrete photon absorbers with dedicated pumps along with compact thin-walled stainless steel chambers*. Two types of photon absorbers have been designed to withstand a total power of up to 2.25 kW and a peak power density of up to 224 W/mm², respectively. The absorber design incorporates a grazing incidence angle on the irradiation surface to reduce power density, a shielding structure designed to confine scattered radiation, and a flange integrated without brazing or welding to eliminate the risk of vacuum leaks. Copper-chromium-zirconium (CuCrZr) was chosen as the material for its superior thermal conductivity and high yield strength. Finite-element analysis using ANSYS was employed to optimize the cooling-channel layout and to ensure compliance with maximum allowable temperature and stress limits.

Speaker: Hideki Dewa (Japan Synchrotron Radiation Research Institute)

TUP7689_edited_version.pdf

16:00 Design studies of a high-power infrared–terahertz FEL facility

Design studies of a high-power infrared-terahertz free-electron laser facility are presented. The facility is based on a high-repetition-rate superconducting linac and is designed to generate electron beams with energies up to about 60 MeV. A third-harmonic linearizing cavity and a C-type magnetic chicane are used to control the longitudinal phase space of the bunch. Start-to-end beam dynamics simulations show that the peak current can be increased from about 26 A to about 100 A, while keeping the normalized projected emittance below 1.2 mm mrad. Based on the optimized beam parameters, FEL oscillator simulations are performed for the mid-infrared, far-infrared and THz beamlines. The results show that cavity detuning has a significant influence on the mid-infrared output spectrum, and an appropriate detuning length helps suppress sidebands and multi-peak structures, leading to improved spectral monochromaticity. In the far-infrared range, the phase difference between transverse modes in the rectangular waveguide reduces the on-axis field intensity and leads to a clear reduction of the coupled output power around 85–95 μm. In the THz range, the output power decreases more smoothly with increasing wavelength, and no pronounced narrow spectral gap is observed. These studies provide a basis for beam-parameter selection, cavity-detuning optimization and waveguide-coupling design for high-power long-wavelength FEL operation.

Speaker: Zexin Cao (University of Science and Technology of China)

TUP2638_edited_version.pdf

16:00 Design study of injector system using rf electron gun with gridded thermionic cathode towards soft X-ray free-electron laser

The high-brightness synchrotron radiation facility “NanoTerasu” provides users with extremely stable synchrotron radiation by top-up injecting an electron beam from a 3-GeV linear accelerator into a diffraction-limited storage ring. NanoTerasu plans to develop a soft X-ray free-electron laser (SX-FEL) using the linear accelerator. To realize SX-FEL with practical gain length, it is required that the linear accelerator generates an electron beam with a peak current of 2 kA and a normalized emittance of 2 mm mrad or less. We have already developed a low-emittance electron gun system with a gridded thermionic cathode and have begun designing a low-emittance injector system using the electron gun system. The linear accelerator based on the electron gun system is planned to serve as both the storage ring’s injector and SX-FEL’s driver. This presentation describes the configuration of a compact SX-FEL linear accelerator that can be installed within existing facilities. It also presents a bunch compression scheme while maintaining slice emittance, along with particle tracking simulation results of the new injector system.

Speaker: Takao Asaka (National Institutes for Quantum Science and Technology)

TUP2661_edited_version.pdf

16:00 Design, fabrication and low-power measurements of an X-band parallel-coupled accelerating structure

To meet the requirement for high-gradient accelerating structures in future compact accelerator systems, this work presents the design, fabrication, and preliminary testing of an X-band 11.424 GHz parallel-coupled accelerating structure. The structure consists of 16 cells and operates in the π mode, with an optimal filling time of approximately 50 ns under over-coupling conditions. The prototype has been successfully fabricated, followed by low-power measurements and bead-pull field distribution. The results show that machining errors are within 5 µm, satisfying the tolerance requirements. These results provide a solid foundation for the subsequent high-power tests.

Speaker: Zhicheng Huang (University of Science and Technology of China)

TUP7615_edited_version.pdf

16:00 Design, Fabrication, and Test of A TM020-mode Cavity with Elliptical Choke for Super Tau-charm Facility

An improved TM020-mode RF cavity has been developed for the collider rings of the Super Tau-Charm Facility (STCF). By utilizing a higher TM020-mode for beam acceleration, this cavity has a lower R/Q = 83.5 Ω and a higher unloaded Q = 61300, compared with conventional TM010-mode cavities. These characteristics help reduce the required detuning frequency and significantly suppress coupled-bunch instabilities (CBIs) driven by the accelerating mode. The optimized cavity operates at 499.7 MHz and provides an effective accelerating voltage Va= 0.6 MV. An elliptical choke is employed to reduce leakage power, achieving less than 2% power loss in the accelerating mode. In addition, harmful parasitic modes other than the TM020-mode are effectively suppressed by positioning the elliptical choke at the magnetic node of the operating mode. After fabrication, the cavity prototype was precisely tuned, and low-power RF measurements were performed. The measured results show good agreement with the simulations, confirming the performance of the improved TM020-mode cavity.

Speaker: Chengzhe Wang (University of Science and Technology of China)

TUP7609_edited_version.pdf

16:00 Deterministic Longitudinal Control of Electron Beams for Universal Light Sources via Spatiotemporal Laser Shaping: Demonstration at LCLS-II

Next-generation XFELs require electron beams with reproducible current profiles, reduced longitudinal curvature, and stable compression behavior. At LCLS-II, we employ a hybrid programmable-laser architecture: combining IR-domain programmable shaping with dispersion-controlled nonlinear synthesis (DCNS)*, to generate tuned flattop ultraviolet (UV) temporal profiles that reshape the longitudinal phase space upstream of collective effects. Using tens of picoseconds UV flattops, we obtain smooth, uniform, low-curvature current distributions at 80 pC. The shaping supports strong, linear compression and reproducible 1.9–2.0 kA peak currents without downstream re-optimization. These results establish source-level flattop shaping as a practical route to improved stability, compression tolerance, and brightness in MHz-class XFELs, and a flexible tool for future adaptive beam-delivery modes.

Speaker: Jack Hirschman (Stanford University, SLAC National Accelerator Laboratory)

16:00 Developing a Hybrid Accelerating Structure Based on Short-Pulse Structure Wakefield Acceleration

Structure Wakefield Acceleration (SWFA) powered by ultra-short RF pulses (~10 ns) generated by Two-Beam Acceleration (TBA) at the Argonne Wakefield Accelerator (AWA) has demonstrated effective suppression of RF breakdowns and achieved gradients exceeding 400 MV/m at X-band frequencies. To fully exploit the benefits of this short RF pulse operation, an accelerating structure must simultaneously achieve two goals: high group velocity (Vg) to ensure rapid RF filling (need for high efficiency), and simultaneously maintain high shunt impedance (R) (need for high accelerating gradient). Conventional accelerating structures involve inherent tradeoffs between these parameters, limiting their effectiveness in the short-pulse regime. To this end, we developed a hybrid structure composed of two co-optimized sub-structures fed by one coupler at the middle: one backward wave (BW) filling and one forward wave (FW) filling sub-sections. This design not only preserves the short-pulse advantage but also amplifies the beam’s energy gain by effectively doubling the acceleration length without requiring extended RF pulse duration. In this work, we present the full RF design, wavefield and transient analysis, and beam-dynamics optimization for high-brightness operation, demonstrating the performance and feasibility of this novel short-pulse BTW–FTW accelerating concept.

Speaker: Chunguang Jing (Euclid Techlabs (United States))

TUV3301_edited_version.pdf

16:00 Development and Magnetic Characterization of Thailand’s First In-Vacuum Wiggler Prototype.

This paper details the development of Thailand’s first prototype in-vacuum wiggler (IVW). The project initiated with 3D magnetic field simulations using the RADIA package to define the optimal magnetic configuration. To verify their magnetic properties and ensure field quality, individual magnet blocks are characterized using a Helmholtz coil system operated via in-house developed control software. The magnet arrays are assembled onto an in-vacuum girder utilizing a custom workstation and specialized keeper tools to maintain strict mechanical tolerances and ensure safety against strong magnetic forces. Optical alignment using a leveling camera verifies girder planarity and gap consistency prior to final metrology. Furthermore, this work details a custom-built Hall probe measurement bench—also driven by newly developed control and data acquisition software—which is employed for the inaugural field mapping of the assembled IVW. A preliminary comparison between the experimental field data and RADIA simulations, prior to the application of shimming or magic finger end-field corrections, is presented. This study establishes a critical technical framework for future high-performance ID development in Thailand.

Speaker: Noppharit Wasanbongngem (Synchrotron Light Research Institute)

TUP7734_edited_version.pdf

16:00 Development and operation of 166.6 MHz SRF modules at HEPS

The storage ring of the High Energy Photon Source (HEPS) is driven by 166.6 MHz β=1 quarter-wave superconducting cavities. Five higher-order-mode-damped 166.6 MHz cavities were designed to provide a total of 850 kW beam power and to accelerate the electron beam to 200 mA. The beamline elements of the module were designed to meet the compact requirements. Given the large beam aperture of 505 mm to realize HOM damping, an exquisite clean assembly procedure was developed and demonstrated with excellent rf performance preserved from vertical tests to horizontal tests. Five cryomodules have been successfully assembled and horizontally tested. The cavity’s Q0 at the design voltage of 1.2 MV reached 1.5e9~2.1e9 at 4 K corresponding to 5~7 W dynamic heat loads in the horizontal tests, comfortably exceeding the design goal. Field emission was less than 0.13 mSv/h during the entire test up to a rf voltage of 1.6 MV, equivalent to a peak electric field of 43 MV/m. Subsequently, five modules were installed in the HEPS tunnel. A beam current of 100 mA was successfully achieved in September 2025. This work represents the first successful implementation of superconducting QWRs as the main accelerating system for a high-current storage ring, thereby extending their application limits from the conventional use in low-beta accelerators to high-current electron storage rings, and establishing them as a proven technology for future high-performance light sources.

Speaker: Pei Zhang (Institute of High Energy Physics)

16:00 Development and Vacuum Performance Evaluation of PEEK 30% CF Vacuum Chambers for High-Repetition-Rate Particle Accelerators

Particle accelerators are continuously advancing toward high repetition rates, aiming to provide higher energy and beam intensity for frontier research across multiple disciplines, including nuclear physics and life sciences. However, the increase in repetition rate intensifies the eddy current effects induced by high-frequency magnetic fields in the vacuum chamber walls, becoming a critical bottleneck limiting accelerator performance improvement. Currently, aluminum oxide ceramic vacuum chambers are widely adopted; yet ceramics suffer from structural instability under high-temperature operating conditions, resulting in insufficient engineering reliability. Polyetheretherketone (PEEK) exhibits promising potential as a novel bulk material for magnetic component vacuum chambers due to its excellent mechanical strength, thermal resistance, chemical stability, and radiation tolerance. This work systematically investigated the outgassing rates of PEEK 30% CF (carbon fiber-reinforced) samples with thicknesses ranging from 4 to 12 mm, revealing that the outgassing rate increases with thickness. Furthermore, an extrusion-fabricated PEEK vacuum chamber prototype—600 mm in length and 100 mm in inner diameter—was developed. A Cu film approximately 2 μm thick was deposited on the inner surface of the prototype via magnetron sputtering. After baking at 120 °C, the coated prototype achieved an ultimate pressure of 3.2×10-8 mbar, demonstrating favorable vacuum performance.

Speaker: Ningfei Wei (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Development and Validation of Aluminum Vacuum Chamber Prototypes for the SPS-II Storage Ring

The development of the Siam Photon Source II (SPS-II), a fourth-generation light source, represents a significant leap in Thailand’s synchrotron infrastructure. A primary objective of the project is the establishment of domestic technical expertise and industrial capability for producing high-precision vacuum components. This paper details the manufacturing and geometric validation of two critical aluminum alloy prototypes: a straight-section chamber and a bending chamber.
Key technological advancements include the optimization of domestic aluminum extrusion processes to achieve ultra-high vacuum (UHV) surface requirements and the implementation of oil-less, ethanol-cooled CNC machining to eliminate hydrocarbon contamination while maintaining high precision. A comprehensive metrology framework, utilizing laser trackers and high-resolution profiling, was employed to characterize manufacturing-induced distortions. Results confirm that the integrated fabrication workflow, which combines specialized internal fixturing and multi-pass TIG welding, successfully maintains the stringent geometric tolerances required for the storage ring. This work validates the technical readiness of Thailand’s industrial sector for the full-scale production of the SPS-II vacuum system.

Speaker: Thanapong Phimsen (Synchrotron Light Research Institute)

TUP7695_edited_version.pdf

16:00 Development of a Fast-feedback Deflector Magnet Power Supply for The Next Generation Heavy Ion Therapy

Application of a 10 Hz fast-cycling induction synchrotron (IS) to the next generation of heavy ion therapy called Energy Sweep Compact Rapid Cycling Hadron Therapy (ESCORT), where the ion beam with energy sweeping is delivered tracking a tumor target in a deformed and moving organ and monitoring the irradiation dose profile in a real-time during irradiation, is under investigation* ** in the collaboration of KEK and SAMEER. To enable precise targeting, this power supply must allow the deflector magnet to shift the beam irradiation position accurately by varying the peak current value for each pulse with the excitation pattern of the main magnet system. This paper describes the initial experimental results obtained by combining a prototype power supply with a steering magnet.

Speaker: Katsuya Okamura (High Energy Accelerator Research Organization)

TUP7666_edited_version.pdf

16:00 Development of a GaN-FET-based fast corrector magnet power supply for the TPS

A modular GaN-FET-based fast corrector magnet power supply has been developed for the Taiwan Pho-ton Source (TPS). The high switching speed of GaN devices enables a significant increase in the output current bandwidth, which improves the response of the fast orbit feedback (FOFB) system and enhances the overall beam stability and photon beam quality of TPS. In the existing FOFB system, the operating current of the corrector magnet power supply is within ±5 A. The developed power supply provides a maximum output current of ±5 A and achieves improved current resolu-tion by optimizing the internal turn ratio of the DC current transformer (DCCT). A digital control architec-ture is implemented, integrating an ADC interface, interlock protection, and a PI controller, and is fully compatible with the TPS control system. With a switch-ing frequency of 250 kHz, the proposed power supply achieves a current control bandwidth of approximately 9 kHz, providing a significant improvement over the existing system.

Speaker: Bao-Sheng Wang (National Synchrotron Radiation Research Center)

TUP7669_edited_version.pdf

16:00 Development of a length-scalable discharge plasma source for the AWAKE experiment toward 10–100 m GeV-energy plasma wakefield acceleration

Plasma wakefield acceleration (PWFA) is a promising route to compact, high-energy accelerators. Achieving TeV-scale electron energies for high-energy physics experiments requires multiple acceleration stages in electron-driven PWFA schemes, which remains a significant challenge.
The AWAKE experiment at CERN explores a proton-driven approach, utilising the kJ-level energy of proton bunches from the Super Proton Synchrotron for single-stage acceleration. A key challenge in scaling this approach is the development of long, highly uniform plasma sources—capable of maintaining electron-density uniformity better than 0.25%—to extend acceleration lengths to 10–100 metres, enabling energy gains of several to tens of GeV.
This work presents the development and characterisation of a length-scalable pulsed-DC discharge plasma, producing the required electron densities in direct-current discharges at 10–50 Pa in noble gases. A 10 m prototype was tested in AWAKE by propagating the 400 GeV proton bunch through the plasma and observing the induced self-modulation. The plasma density and uniformity were characterised, and length scalability was investigated by combining multiple discharges in series using shared electrodes and magnetic circuits for current balancing. The results presented here demonstrate the potential of this scalable plasma technology for future PWFA applications.

Speaker: Carolina Amoedo (European Organization for Nuclear Research)

16:00 Development of a Modular Magnet Power Supply with Parallel Operation for the Korea-4GSR Storage Ring

The storage ring of the Korea-4GSR (Korea 4th Generation Synchrotron Radiation) facility currently under construction consists of a total of 1184 magnets, of which 792 are large-capacity magnets requiring rated currents of 140A or 280A.
To drive these large-capacity magnets, magnet power supplies (MPSs) are required to support parallel operation in order to minimize the number of MPS types, thereby improving maintenance efficiency and reducing manufacturing costs. In addition, to ensure beam stability and low-emittance beam performance, current stability of less than 10 ppm and accuracy of less than 100 ppm under long-term operation are required during the prototype development.
This paper presents a storage ring modular magnet power supply (SR Modular MPS) rated at 140A, which is designed in a modular form with master–slave-based parallel operation capability, allowing the rated output current to be expanded up to 280A through two-unit parallel operation.
The proposed MPS can supply both 140A and 280A rated currents to large-capacity magnets using a single MPS type, and satisfies the MPS performance requirements over the entire operating range through a compensation method applied based on operating-condition-dependent characteristics.
Experimental results demonstrate that the developed SR Modular MPS achieves a stability of 2.28 ppm and an accuracy of 45.79 ppm in single-unit operation, and a stability of 5.1 ppm and an accuracy of 45.88 ppm in parallel operation.

Speaker: Hyeonjun Jang (Pohang Accelerator Laboratory)

TUP7668_edited_version.pdf

16:00 Development of a novel solid-state modulator and its application in high-power klystrons

This paper presents a highly integrated solid-state modulator designed to drive high-power klystrons in linear accelerators. The modulator employs a vertically integrated architecture in which the solid-state module array is directly combined with the high-voltage pulse transformer. This configuration eliminates long high-voltage cable connections, reduces parasitic inductance, and improves compactness and maintainability. The proposed modulator has been experimentally validated in high-power tests with an 80 MW S-band klystron at the Hefei Advanced Light Facility (HALF), achieving the required pulse waveform quality and stability. In addition, with limited modification, the same architecture can be adapted to higher repetition-rate applications such as the Super Tau-Charm Facility (STCF) injector, demonstrating its scalability for future large-scale accelerator facilities.

Speaker: Mr Zichen Zhong (University of Science and Technology of China)

TUP7644_edited_version.pdf

16:00 Development of an attractive force measurement system for In-Vacuum Undulator for SPring-8-II

In undulator development, strong attractive force acting between the top and bottom magnetic arrays is one of the important factors for determining the required specification of an undulator flame. An attractive force cancellation scheme using monolithic multipole magnets is implemented in In-Vacuum Undulator for SPring8-II(IVU-II) to relax the required specification. In theory, the scheme could compensate the attractive force completely, however, remaining force due to the error of magnetization of magnet pieces and misalignment of magnets is unavoidable in assembling the undulator magnet array. In order to evaluate the effectiveness of this scheme, we developed an attractive force measurement system, where one of the magnetic arrays was moved using a pair of lack and pinions located at Bessel points of the top magnetic array, while the bottom side was fixed. The distance of two magnetic arrays, namely the undulator gap, was monitored using a laser displacement sensor. The magnetic force acting on the magnetic arrays was measured using two load cells as a function of the undulator gap. In this presentation, we will give the detail of the system and some of the measurement result.

Speaker: Kei IMAMURA (Japan Synchrotron Radiation Research Institute)

16:00 Development of an ion beam analysis setup at the Bonn Isochronous Cyclotron

The Bonn Isochronous Cyclotron provides light ion beams with a charge-to-mass ratio Q/A ≥ 1/2 and kinetic energies below 14 MeV per nucleon to one of five experimental sites. It is planned to extend the facility’s analytic capabilities through the development and installation of an ion beam material analysis setup.

It is intended to use low energy alpha particles with energies between 2 and 5 MeV, with investigations on whether to achieve this through a higher harmonics mode of the cyclotron or energy dispersive elements in the beamline currently under way.

The analytic methods will be Rutherford backscattering (RBS), which is a method sensitive to the mass of a nucleus, and particle induced x-ray emissions (PIXE) which is used to detect characteristic x-ray emission lines to disambiguate isobars.
The experimental setup is currently in development and will house a surface barrier detector (SBD) for RBS, a small number of SBDs for beam characterization and a silicon drift detector for PIXE measurements.

This contribution will give an overview over the development process, some preliminary detector tests and a preparatory benchmark x-ray measurement.

Speakers: Dennis Sauerland (University of Bonn), Henry Schumacher (University of Bonn)

16:00 Development of gas target systems for laser-plasma accelerators

Laser–plasma acceleration experiments rely critically on advanced gas-target systems capable of delivering well-defined density profiles within a high-vacuum environment. The properties of the resulting particle beams and radiation are highly sensitive to the target’s density distribution, making precise control and characterization essential. In this contribution, we present the development of gas targets designed for a broad range of high-repetition-rate laser–plasma experiments driven by high-intensity, ultrashort laser pulses. Hydrodynamic simulations of neutral gas flow are employed to guide target design, followed by experimental characterization using interferometry combined with tomographic density reconstruction. To enhance interaction stability, the targets are optimized for continuous-flow operation. We investigate conical and slit-type supersonic nozzles as well as advanced multi-component nozzle assemblies. Novel extended-length nozzles and dual-stage target configurations are introduced. Additionally, we describe the design and implementation of a differential pumping system enabling stable operation of continuous-flow supersonic nozzles in a vacuum environment.

Speaker: Sebastian Lorenz (Extreme Light Infrastructure ERIC (Czech Republic))

16:00 Development of High-Gradient, Fast-Response, Broadband RF Systems Employing Magnetic-Alloy-Loaded Cavities for the HIAF Booster Ring

The High Intensity Heavy-ion Accelerator Facility (HIAF) is currently under construction at the Institute of Modern Physics (IMP), Chinese Academy of Sciences. It aims to deliver high-intensity heavy-ion beams for exploring effective interactions within atomic nuclei, revealing the origin of heavy elements in the universe, and addressing key technical challenges related to irradiation effects. To fulfill functions including beam capture, acceleration, merging, and compression, five RF systems are implemented in the HIAF booster ring. These systems operate across a frequency range of 0.29 MHz to 2.1 MHz, with gap voltages of up to 70 kV. Each system uses magnetic alloy-loaded cavity driven by tetrode-based amplifier. Each cavity incorporates 24 Φ780mm high-performance domestic magnetic alloy ring cores. To achieve precise stabilization of amplitude and phase, a new multi-harmonic digital low-level RF control system based on VPX architecture has been developed， capable of regulating harmonics from the 1st through the 8th. This presentation will cover the latest developments and test results for the RF systems.

Speaker: Yan Cong (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Development of in situ thickness sensor for vapor diffused Nb3Sn films

Fermilab is one of the leaders in development of vapor diffused Nb3Sn films inside niobium cavities. This material has a higher critical temperature (Tc) than niobium, enabling cavity operation at 4.2 K. This higher operational temperature significantly reduces the infrastructure required for cooling compared to 2 K systems, making superconducting radio-frequency (SRF) technology more accessible. Current deposition methods have relied on iterative testing to determine nominal film thickness, a process that can be time-consuming and imprecise. To address this, we are developing a sensor to measure the thickness of Nb3Sn thin film in situ during vapor diffusion. Our design involves a four-point resistance measurement of a thin film of niobium, inside the coating region. During coating, the change in resistance reflects the conversion of the film from Nb to Nb3Sn, which allows simple integration with the current furnace infrastructure. This sensor would allow real time measurement of the Nb3Sn film thickness, allowing for increased precision in future depositions for cavity applications.

Speaker: Katrina Howard (University of Chicago)

16:00 Development of in-situ field measurement system for Korea-4GSR in-vacuum undulators

Precise magnetic-field characterization of in-vacuum undulators is essential for achieving stable beam dynamics in synchrotron light sources. This work presents an in-situ measurement platform that integrates a SAFALI-based Hall probe scanner with a stretched-wire measurement system. The Hall probe unit measures the local magnetic-field distribution along the undulator, achieving micrometer-level positioning accuracy through laser interferometry and optical feedback. In parallel, the stretched-wire system enables reliable determination of the first and second magnetic-field integrals. To minimize magnetic distortion, most mechanical structures are fabricated from low-permeability materials. The system is designed to characterize in-vacuum undulators with magnetic lengths of up to 3 m, allowing comprehensive field mapping without removing the vacuum chamber. The integrated platform is currently under construction for application to in-vacuum undulators at the Korea-4GSR Facility and is expected to improve phase-error reproducibility while providing direct verification of undulator magnetic performance.

Speaker: Geonhee Choi (Korea Basic Science Institute)

TUP2716_edited_version.pdf

16:00 Development of VHEE Scattering Systems for FLASH Radiotherapy

Very High Energy Electrons (VHEE) are an emerging radiotherapy modality offering magnetic steering and focusing for conformal treatments, with potential for compact, cost-efficient clinical systems. VHEE beams may also enable Ultra-High Dose Rate (UHDR) delivery for the FLASH effect, which can selectively spare healthy tissue while maintaining tumour toxicity. A key challenge is achieving transversely uniform VHEE dose at UHDR, as current magnets cannot scan large tumour volumes within FLASH timescales (~0.1 s). Conventional dual-scattering systems—using a pre-scatterer for magnification and a Gaussian scatterer for flattening—are unsuitable at VHEE energies, generating substantial photon contamination unless the beamline is greatly extended.
This work replaces the pre-scatterer with a quadrupole lattice that magnetically enlarges the beam while reducing Bremsstrahlung. RF-Track and TOPAS simulations show that an optimised quadrupole-scatterer design produces a 75 mm uniform field and reduces photon yield by 94.5% compared with dual-scattering. BDSIM confirms the modelling. Experimental validation at CLEAR at CERN is in preparation, and an optimiser is being developed to design quad-scatterer systems for generic VHEE machines using existing quadrupoles. These results suggest that magnetic beam magnification upstream of a Gaussian scatterer is a promising route to FLASH-compatible VHEE therapy with reduced secondary radiation and improved dose conformity.

Speaker: Wilfrid Farabolini (European Organization for Nuclear Research)

TUP8016_edited_version.pdf

16:00 Digital signal component separator for the LANL solid-state power amplifier

Because of aging, and product discontinuity, LANSCE is investigating the replacement of high power RF amplifi-ers. A promising candidate is the GaN solid-state power amplifier (SSPA). The outphasing technique provides high efficiency operation of the SSPA. A key element of the outphasing technique is the signal component separa-tor(SCS), which converts an Amplitude Modulation-Phase Modulation(AM-PM) signal to two PM only sig-nals. In this paper, a design of a digital signal component separator (DSCS) in In-phase/Quadrature(I/Q) coordinate is addressed. In addition, the feedback linearizers are pro-posed to suppress the input disturbances to the SSPA. The DSCS is implemented on the present Field Pro-grammable Gate Array(FPGA) based LANSCE digital low level RF (DLLRF) control system. The performance of the DSCS on the cavity field control system is verified on a low power teststand and the results are reported.

Speaker: Sungil Kwon (Los Alamos National Laboratory)

TUP7342_edited_version.pdf

16:00 Dipole powering failure criticality and mitigation for FCC-ee

The electron-positron Future Circular Collider (FCC-ee) will initially operate at the Z-pole energy of 45.6 GeV with beams composed of 12 000 bunches, storing a total energy of 17.5 MJ per beam. Combined with small emittances, this results in extremely high beam energy densities that pose a significant damage risk to accelerator components. A comprehensive
assessment of powering failure scenarios is therefore essential to ensure safe machine operation. This study evaluates the impact of a powering failure in one of the main dipole circuits using the Local Chromaticity Correction (LCC) lattice configuration. Multi-turn bunch tracking simulations are performed to determine the beam response and assess failure criticality. We interpret these novel results with respect to previously established results for the Global Hybrid Correction (GHC) lattice. Horizontal orbit excursions are found to develop over a significantly longer timescale than for the GHC lattice. The underlying physics of this behaviour is analysed in detail, with emphasis on
the role of the modified sextupole configuration in the arcs. Based on these findings, the implications for machine protection system design, including interlocking requirements and detection strategies, are discussed and mitigation measures are proposed.

Speaker: Delphine Domange (European Organization for Nuclear Research)

16:00 Dual beam dynamic modes in a Compact Standing Wave Linear Accelerator

Tong Chen (RefleXIon Medical Inc.)
Hao Tao, Liang Huo, Tong Li, Zhen Feng, Lin Zhou, Yongtao Liu (Chengdu Elekom Vacuum Electron Technology Co. Ltd)
It has been commonly observed that the beam spot profile of compact standing wave linacs have a dual Gaussian distribution. Further study of this paper shows that the two Gaussian distribution is generated by different acceleration process and beam dynamics. Simulation data analysis concludes that the particles in the two Gaussian distributions are strongly dependent on their initial phases. Experiment results have demonstrated the two Gaussian distributions responded differently to steering magnetic field.

Speaker: Yongtao Liu (Xihua University)

TUP2333_edited_version.pdf

16:00 Dynamic aperture prediction based on machine learning

The dynamic aperture(DA) is one of the most important parameters of nonlinear beam dynamics in storage rings. It describes the transverse phase space region where the motion of a particle can remain stable. In the design and optimization of storage rings, long-term particle tracking is usually required to ensure an sufficient DA. However this process is very time consuming. This study explores the possibility of using machine learning methods for DA prediction. Firstly, several regression models from magnet strengths to resonance driving terms are constructed using different machine learning methods, showing that the use of machine learning can be applied to the nonlinear performance analysis of storage ring lattice. Then predictive regression models from magnet strength to DA are constructed, and the results show that artificial neural network have better prediction accuracy. The method will be further developed for nonlinear analysis and optimization of storage ring.

Speaker: Jincheng Xia (University of Science and Technology of China)

TUP2626_edited_version.pdf

16:00 Effect of filling modes on boiling heat transfer mechanisms in liquid nitrogen cooling system

Liquid nitrogen (LN2) cooling is widely utilized in the cooling systems of superconducting devices and scientific instruments. During the cooling process, the boiling heat transfer mechanism plays a decisive role. When the solid surface temperature significantly exceeds the saturation temperature of the liquid nitrogen, the Leidenfrost effect occurs, forming a vapor film at the solid-liquid interface that drastically reduces heat transfer efficiency. Previous research has primarily focused on altering the boiling curve and enhancing the Critical Heat Flux (CHF) through surface roughness, micro-nano structures, or various material properties. Few studies have explored the impact of filling modes within the cooling system on disrupting the vapor film and improving boiling heat transfer.This study utilizes a self-developed liquid nitrogen cooling experimental platform to investigate four distinct filling and cooling modes designed for an Oxygen-Free High Conductivity (OFHC) copper test block. By examining the boiling curves under various filling modes, this thesis analyzes the underlying mechanisms influencing the wall superheat at the Leidenfrost point ($\Delta T_{LP}$) and the Critical Heat Flux ($\Delta T_{CHF}$). The results indicate that the bottom-filling method, characterized by impingement kinetic energy, effectively increases fluid disturbance and disrupts the vapor film encapsulation. This significantly reduces the duration of the Leidenfrost effect and facilitates an earlier transition into the high-efficiency nucleate boiling stage.

Speaker: Ping-Shun Chuang (National Synchrotron Radiation Research Center)

TUP7674_edited_version.pdf

16:00 Effect of laser pulse power change on wake bubble size and accelerated electron bunch parameters during LWFA in a conical plasma channel

Laser wakefield acceleration is considered a promising and efficient method for increasing electron bunches energy. Despite advantages in acceleration gradients (accelerating field amplitudes up to 1 TV/m), the issue of dephasing between the electron bunch and the accelerating field, caused by the bunch energy gain, remains a complex task. The use of a conical plasma channel leads to an increase in bunch energy due to laser guiding and compression within the channel.
This study demonstrates that increasing the laser pulse power enhances the electron bunch energy but significantly alters the wake bubble shape. This is results in the absorption of the electron bunch by the rear wall of the wake bubble, as well as leads to dephasing between the bunch and the accelerating field.
Using numerical simulations, the dependencies of bunch parameters, including energy and dimensions, on laser power were obtained. It was shown that found optimal laser power values provided a balance between avoiding bunch absorption and maximizing energy gain.

Speaker: Mariia Seniak (Lviv University)

16:00 Effect of Proton Bunch-Induced Impact Ionization on a Witness Electron Bunch in AWAKE Run 2c External Injection Region

The injection of the witness electron bunch in the AWAKE Run 2c experiments will occur in a $\sim30\,$cm gap separating two plasmas. In this gap, the $400\,$GeV, self-modulated drive proton bunch and witness bunch will co-propagate in a Rubidium vapor. This vapor will be partially ionized by the protons through impact ionization, and will thus result in the presence of a low-density ($\sim10^{12}\,$cm$^{-3}$) plasma. Under the influence of the space-charge fields induced by the proton bunch, the plasma electrons form an on-axis filament that acts as a defocusing element for the witness electron bunch. This filament may prevent proper matching of the witness bunch in the second plasma, and/or lead to emittance growth before injection. In this work, we investigate, using numerical simulations, the process of impact ionization resulting from the propagation of the protons, the formation of the plasma electron filament, and discuss its potential effect on the witness electron bunch.

Speaker: Arthur Clairembaud (Max Planck Institute for Physics)

16:00 Efficiency enhancement in regenerative amplifier free-electron lasers using a tapered undulator

Recent progress in short wavelength free-electron lasers (FELs) from the extreme ultraviolet through x-rays has opened new avenues for industrial and research applications. Most such FELs rely on Self-Amplified Spontaneous Emission (SASE) in which the optical pulse grows from noise in a single pass through the undulator. However, this results in significant shot-to-shot fluctuations in the power and spectrum. Oscillators are under consideration to stabilize the noise associated with SASE. In particular, a high-gain/low-Q oscillator, i.e., a regenerative amplifier free-electron laser (RAFEL), is one possible concept. In this paper, we present the first analysis of efficiency enhancement in a RAFEL with a long, tapered undulator line and demonstrate substantial enhancements in the brightness of the optical output. Here, we consider a high average power EUV RAFEL at 13.5 nm and show that the performance exceeds that of single-pass, tapered self-amplified spontaneous emission. This points the way to high power tapered undulator x-ray RAFELs.

Speaker: Henry Freund (University of Maryland, College Park)

16:00 Efficient design of an 8-conductor nonlinear kicker for HALF using a python-based toolchain

An 8-conductor nonlinear kicker (NLK) is proposed for the Hefei Advanced Light Facility (HALF) injection system. Its design is highly sensitive to conductor positions and must accommodate a vacuum chamber. This study develops an automated toolchain combining Opera-2D and Python with Bayesian optimization (Optuna) to search for feasible conductor configurations under strict magnetic and spatial constraints. A feasible design was obtained within 40 iterations, greatly improving R\&D efficiency and offering a generalized approach for nonlinear magnet optimization in fourth-generation light sources.

Speaker: Weibo Hu (University of Science and Technology of China)

16:00 ELBA all-optical PW laser - GeV electron collider

Laser wakefield acceleration (LWFA) is the most compact technique to produce GeV electron beams as short as few fs. To achieve optimal LWFA conditions, the laser pulse energy, time duration and focal spot size must be properly set. Limiting factors to the maximum attainable energy are the depletion of the pump laser and the dephasing of the electrons with the accelerating field, since the laser propagates slower than the electrons inside the plasma. The generation of a pre-ionized plasma channel enables a longer acceleration length, maximizing the electron beam energy.
ELBA at ELI Beamlines is a laser-electron collider, based on the Ti:Sa L3-HAPLS laser, designed to deliver up to 30 J, 30 fs pulses at a 10 Hz repetition rate. Once the square 230 mm x 230 mm laser pulses arrive in ELBA, they are 50:50 wavefront split by a full-size dielectric mirror with a 150 mm hole. The round laser pulses are sent to an off-axis parabola that focuses them down to 55 um FWHM focal spot 10 meters downstream. The square hollow laser pulses propagate through a delay line before reaching a 375 mm focal length off axis parabola that focuses them onto the counterpropagating electron beam. ELBA is designed to collide 2 GeV electron beam with 1021 W/cm2 laser pulses. At the moment, ELBA has been commissioned with up to 15 J at 0.2 Hz and up to 8 J at 3.3 Hz, achieving up to 5 GeV electron beams. Six user experimental campaigns have been completed, and the user proposal acceptance rate is around 50%.

Speaker: Gabriele Maria Grittani (Extreme Light Infrastructure ERIC (Czech Republic))

16:00 Electrical integration of the ALS-U storage ring modules

The ALS-U (Advanced Light Source Upgrade) project is an upgrade to the ALS at the Lawrence Berkeley National Laboratory.

The new multibend achromat (Storage Ring) will be installed in 16 months. To meet the tight schedule and space constraints, the 48 modules of magnets (called rafts) are prestaged and aligned in advance. All local electrical wiring is prestaged to reduce the installation time in the tunnel.

Electrical work includes cabling for grounding, thermocouples, MPS (Machine Protection System), magnet power and correctors, vacuum, beamline feedback (diagnostics), and AC cables, all arranged to minimize heat buildup. Key challenges include raft transport requirements and managing the overall routing as well as future upgrades in the tightly packed lattice arrangement.

This contribution presents the electrical integration on the raft during prestaging. It further outlines the testing activities and the prototype rafts developed to validate and optimize installation procedures. It details the schematics, cable and material management for the 48 rafts, as well as the ALS-U configuration management system and databases used for electrical routing.

Speaker: Dmitry Gudkov (Lawrence Berkeley National Laboratory)

TUP2344_edited_version.pdf

16:00 Electromagnetic-thermal coupling study of the SHINE injector cavity

The SHINE project is a high-repetition-rate hard X-ray Free Electron Laser (XFEL) facility driven by a superconducting RF linear accelerator with an energy exceeding 8.0 GeV. The linear accelerator (LINAC) of SHINE consists of six hundred 1.3 GHz 9-cell cavities for acceleration, producing photons with energies ranging from 0.4 to 25 keV. This study focuses on the first single-cavity cryomodule of the LINAC which follows the electron gun. The injector cavity is a 1.3 GHz axisymmetric superconducting cavity with two fundamental power couplers. The accelerating gradient of the cavity reached 28 MV/m in the vertical test, but was limited below 8.1 MV/m in the horizontal test by thermal runaway. This did not meet the specification of 12 MV/m. Experiments revealed that the cause of thermal quench was insufficient cooling. Electromagnetic-thermal coupling simulation was performed to analyze this phenomenon and optimize the cooling conditions. The original cooling setup was enhanced and several new cooling configurations were proposed in the simulations. The optimization schemes showed a significant increase in the accelerating gradient. The injector cavity met the specification in horizontal test after applying the enhanced cooling scheme.

Speaker: Xinghao Guo (Shanghai Advanced Research Institute)

16:00 ELIMAIA-ELIMED: An Operational Beamline for Radiobiology Experiments with Laser-Driven Proton Beams

With the growing interest in advanced radiotherapy approaches, laser-driven accelerators offer a potential alternative to conventional technologies. At ELI Beamlines, the ELIMAIA–ELIMED beamline has matured into an operational platform capable of delivering multi-shot laser-driven proton (LDP) beams for radiobiological studies. The system, powered by the L3 HAPLS 1 PW laser, currently provides protons with cut-off energies up to ~40 MeV and controlled exposures in the mGy–Gy range. Ongoing developments in stability, transport, and dosimetry continue to enhance its suitability for systematic investigations.
Initial fibroblast experiments showed comparable DNA double-strand break induction between multi-shot and single-shot LDP exposures and conventionally accelerated protons. More recent campaigns target tumor cell lines grown as 3D spheroids, a physiologically more relevant model. These studies examine survival, transcriptional responses, and stress-related protein expression after LDP irradiation, supported by conventional benchmarks. Bulk RNA sequencing has been performed and is under evaluation, while protein assays—including PD-L1, HSP70, and HSP90—are underway to assess changes linked to beam’s temporal structure.
Together, these activities demonstrate that ELIMAIA–ELIMED has transitioned into an actively used, user-ready platform for radiobiological research, offering unique beam characteristics and expanding experimental capabilities for ultrafast-radiobiology studies.

Speaker: Pavel Bláha (Extreme Light Infrastructure Beamlines)

16:00 Elliptical beam shaping in a standard bow-tie planar four-mirror optical enhancement cavity using a cylindrical lens

The standard bow-tie (SBT) planar four-mirror optical enhancement cavity can amplify laser power, circulate laser pulses, and adjust the laser beam waist. It is widely applied in fields such as steady-state micro-bunching light sources, inverse Compton scattering light sources and fusion energy. However, the different effective radii of curvature in the sagittal and tangential directions vary with the incidence angle, which in turn leads to an elliptical cavity mode. Conventional approaches suppress this effect by restricting the transverse dimensions of the cavity, but this sacrifices the transverse design freedom of the optical enhancement cavity.
This paper proposes an elliptical cavity mode correction method using a cylindrical lens, enabling the fundamental mode at the beam waist to recover a circular shape. The method utilizes a cylindrical lens to differentially compensate the wavefront curvatures in sagittal and tangential directions, eliminating elliptical spot distortion without compressing the transverse dimensions of the cavity. Consequently, it overcomes the de-sign constraints on the transverse size of the optical enhancement cavity and provides a new approach for designing large-volume, high-power optical enhancement cavities.

TUP2687_edited_version.pdf

16:00 Enhanced coherent terahertz generation in storage rings with an active demodulation section

Coherent terahertz (THz) radiation sources based on storage rings hold significant future for generating high-average-power THz radiation, owing to the high revolution frequency of the electron beam. However, the achievable repetition rate is limited by the long time required for the ring's damping mechanism to dissipate the phase-space perturbation introduced by the modulation and radiation process. To overcome this bottleneck, we propose a novel scheme that incorporates a dedicated demodulation section to enhance the generation of high-repetition-rate coherent THz radiation. In this scheme, after a seed laser imposes a density modulation and a THz wiggler emits coherent radiation, the electron beam is actively cooled in the demodulation section. This process facilitates the beam's rapid recovery, allowing it to be effectively damped and ultimately reach a new steady state. Simulation results demonstrate that this integrated setup successfully produces coherent THz radiation pulses at a repetition rate of 100 kHz, achieving an average power of 6.2 mW at 10 THz.

Speaker: Xiazhen Xu (University of Science and Technology of China)

16:00 Enhanced superconducting properties of Nb films via a high-power impulse magnetron re-sputtering/sputtering approach for Nb–Cu 1.3 GHz RF cavities

Conformal deposition of high-performance superconducting films on complex cavity geometries, particularly ensuring robust film-substrate adhesion, remains a fundamental challenge. We address this by introducing a novel high-power impulse magnetron re-sputtering and sputtering (HiPIMRS) system designed for uniform niobium (Nb) film deposition on the interior surfaces of 1.3 GHz copper cavities. A key innovation is an in-situ copper substrate re-sputtering step prior to Nb deposition, which eliminates interfacial oxides and degradation, ensuring atomic-scale interfacial integrity. Through in-situ re-sputtering prior to deposition, we achieve oxide-free Nb/Cu interfaces with atomic-scale integrity. Crucially, electrical transport measurements demonstrate a significant enhancement in the superconducting transition temperature from 8.5 K to 9.3 K for HiPIMRS films, along with smooth surfaces (Rₐ < 20 nm) and a preferred (110) orientation. This work establishes HiPIMRS as a viable pathway for next-generation superconducting radiofrequency (SRF) cavity production, with its interfacial engineering protocols offering significant advancements in film conformity and superconducting properties.

Speaker: JianJun XIAO (ShanghaiTech Laboratory for Topological Physics, School of Physical Science and Technology, ShanghaiTech University, State Key Laboratory of Quantum Functional Materials, School of Physical Science and Technology, ShanghaiTech University)

TUP7731_edited_version.pdf

16:00 Entropy generation analysis of heat loads in an SSR2 superconducting cryomodule

The SSR2 superconducting cryomodule is analyzed in terms of static and dynamic heat loads and the associated entropy rates at the 2 K stage. The reference cryomodule contains six superconducting single-spoke resonator cavities. Static heat loads arise from conduction through cryomodule supports, couplers, cables, and beam-pipe interfaces, and from radiation through the insulation vacuum. Dynamic heat load is produced by radio-frequency surface dissipation. At 2 K, static and dynamic heat loads of 20 W and 80 W correspond to entropy rates of 10 W/K and 40 W/K, respectively, for a total cold-stage entropy rate of 50 W/K. The dynamic contribution ac-counts for 80% of the total entropy rate and scales inversely with the intrinsic quality factor Q₀. A coefficient-of-performance analysis shows that 100 W at 2 K requires at least 14.9 kW in the Carnot limit and about 100 kW for a representative real COP of 0.001. The results show that reducing radio-frequency loss, increasing Q₀, minimizing static heat leakage, and improving refrigerator performance directly reduce entropy generation and improve cryomodule efficiency.

Speaker: Juwan Kim (Institute for Basic Science)

TUP7642_edited_version.pdf

16:00 Estimation of Radiation Field for BDF/SHiP at CERN

The Beam Dump Facility (BDF) will host the Search for Hidden Particles (SHiP) experiment at CERN’s Super Proton Synchrotron. BDF/SHiP is designed to search for feebly interacting particles in a region of mass and coupling accessible only with a dedicated beam-dump configuration*. With a beam intensity of 4E19 POT per year at 400 GeV, the High-Intensity ECN3 (HI-ECN3) Project will enable the search for feebly interacting particles, but the radation field created has the potential to be used parasitically to broaden the physics programme to nuclear astrophysics, materials science, and radiation-to-electronics research. High-momentum protons impinging on a tungsten target generate an intense radiation field leading to cumulative and single-event effects. In this work, the radiation environment and its impact on electronics of the detectors and associated infrastructure were evaluated through simulations performed with FLUKA Monte Carlo code. The results show that proposed optimisation solutions for shielding reduce radiation levels, keeping most effects within acceptable limits. It is also observed that modifications made to the magnetic field and geometry of the muon shield—which controls the deflection of muons produced in the beam dump to reduce flux reaching the detector—influence muon and neutrino backgrounds.

Speaker: Roberto Cala' (European Organization for Nuclear Research)

TUP8027_edited_version.pdf

16:00 Evaluation and mitigation of magnetic cross-talk in the Korea-4GSR storage ring

Korea-4GSR is a new 4 GeV synchrotron light source under construction since 2021, targeting ultralow emittance performance of 60 pm rad. To reach this regime, the lattice uses a hybrid multi-bend achromat (HMBA) configuration, which increases the number of magnets per cell resulting in magnetic cross-talk. The short magnet spacing may degrade field quality, perturbing particle orbits and enhancing nonlinear effects in beam dynamics. 3D finite-element simulations were performed for all magnet pairs in the ring, and no meaningful cross-talk was identified in most configurations. Magnet pairs involving dipoles, however, can alter the bending strength and thus directly impact the beam trajectory, necessitating focused evaluation. For these dipole pairs, we performed both simulations and magnetic measurements and demonstrated that a field-clamp effectively suppresses the residual cross-talk. This poster highlights the mitigation capability of the field-clamp approach.

Speaker: Seohyeon An (Pohang Accelerator Laboratory)

TUP2682_edited_version.pdf

16:00 Evaluation and Mitigation of Residual Magnetic Field from the High-Voltage Pulse Power Supply for the Beam Kicker in the Muon g-2/EDM Experiment

In the J-PARC muon g-2/EDM experiment, precise control of the muon beam is essential to achieve the required measurement accuracy. For this purpose, the development of a new high-voltage and high-current pulse power supply(kicker power supply) is indispensable. Because the accuracy of the g-2 measurement strongly depends on the uniformity of the magnetic field, and the muon beam must remain confined within a region of 10 cm in height and a radius of 33.3 cm, any residual magnetic field leads to a degradation of the precision. While the design of the static magnetic field is being developed to meet the experimental requirements, the residual dynamic magnetic field remains a challenge. In this study, aiming to develop a power supply that satisfies the required precision, we evaluated the impact of the residual magnetic field caused by the kicker power supply on the measurement accuracy. This presentation will report the results of the evaluation and our efforts to reduce the residual magnetic field.

Speaker: Yuta Kawase (Iwate University)

TUP7711_edited_version.pdf

16:00 Evaluation of orbit correction methods for the Helium Light Ion Compact Synchrotron HeLICS

Within the framework of the Next Ion Medical Machine Study (NIMMS) collaboration at CERN, closed orbit correction schemes are developed for the Helium Light Ion Compact Synchrotron (HeLICS) - a novel synchrotron design in development for cancer treatment. Different options for closed orbit correction are presented, including the possibility of applying beam-based quadrupole alignment without dedicated corrector magnets. The limitations and advantages of the different closed orbit correction methods are evaluated against each other in order to determine the best scheme for HeLICS.

Speaker: Foteini Asvesta (European Organization for Nuclear Research)

TUP8013_edited_version.pdf

16:00 Evidence for RF breakdowns causing surface anomalies on caesium Telluride cathodes at Clara

The Compact Linear Accelerator for Research and Applications (CLARA) at Daresbury Laboratory has recently undertaken an upgrade of its photocathodes from using a copper emission surface to using caesium telluride (Cs\textsubscript{2}Te). During the conditioning of the first Cs\textsubscript{2}Te cathode a significant number of RF breakdowns were detected, and so that cathode was replaced; subsequent inspection of the cathode following removal identified a number of surface defects. To better study the second cathode, a diagnostic camera was used to collect images of the surface \textit{in situ} during RF conditioning; the frequent formation over time of surface defects was observed. In this paper we present a statistical analysis of the breakdown events and surface image data, utilizing cross-correlation of the signal derivatives to account for cumulative trends. The analysis reveals a correlation between the rate of defect formation and the incidence of RF breakdowns, with a Pearson coefficient of $r = 0.59$ at zero time lag. These results provide quantitative evidence that RF breakdown events are the likely driver of surface morphology changes on Cs\textsubscript{2}Te cathodes.

Speaker: Amelia Pollard (STFC Daresbury Laboratory, Cockcroft Institute)

TUP3075_edited_version.pdf

16:00 EXOTIC BEAM PRODUCTION AT GANIL FACILITY

The GANIL facility (Grand Accélérateur National d’Ions Lourds) in Caen has been delivering stable and radioactive ion beams since 1982 for experimental research in nuclear physics, atomic physics, radiobiology, and materials science.
At GANIL, radioactive ion beams are produced using two complementary approaches. The first is the Isotope Separation On-Line (ISOL) method implemented at the SPIRAL 1 facility, where radioactive nuclei are produced in thick targets using primary beams with energies up to 95 MeV/u and intensities reaching several microamperes. The extracted ions are charge-bred and accelerated by the CIME cyclotron to energies ranging from 1.2 to 25 MeV/u, with typical beam intensities up to 10⁶–10⁸ particles per second depending on the isotope.
The second approach is the in-flight fragmentation of stable heavy-ion beams (up to uranium) accelerated to energies of 60–95 MeV/u and impinging on a rotating target. The resulting fragments are selected and purified using the LISE spectrometer, providing beams with energies close to the primary beam and intensities typically ranging from 10² to 108 particles per second.
This presentation will describe the production mechanisms, target–ion source systems, charge breeding, beam optics, and separation techniques, and will discuss beam performances in terms of energy, intensity, and isotopic purity for both production modes.

Speaker: Omar Kamalou (Grand Accélérateur Nat. d'Ions Lourds)

16:00 Experience Adjusting Beam Transport and Booster Synchrotron Systems for Different Linac Output Energies at the Canadian Light Source

Due to linac operational issues, the Canadian Light Source has recently reduced the injection energy of its booster synchrotron from 250 MeV to 152 MeV. We found that we needed to be increasingly careful with the booster ring transverse tunes as we decreased the injection energy. We needed to make fine adjustments of the tunes during the low energy part of the ramp, requiring new software. Adjusting the energy compression system (ECS) and transfer line was mostly a linear process. Recent improvements in diagnostics and software have greatly simplified ECS and transfer line setup.

Speaker: Ward Wurtz (Canadian Light Source (Canada))

16:00 Experimental Preparation for Generating Tunable X-ray Frequency Combs at the Shanghai Soft X-ray Free-Electron Laser Facility

X-ray frequency combs (XFCs) hold significant potential for advanced applications in precision spectroscopy, resonant inelastic X-ray scattering (RIXS), and fundamental physics studies. This paper reports on the experimental preparation for generating high-power tunable XFCs at the Shanghai soft X-ray Free-Electron Laser facility (SXFEL). Building on our theoretical framework, we have developed a chirped frequency-beating laser system to serve as the second seed laser in the echo-enabled harmonic generation (EEHG) scheme. The system employs parallel gratings for introducing precise linear chirp and an optical delay line to control the beating frequency. We detail the commissioning of this laser system, including the optimization of critical parameters such as time delay, chirp rate, and pulse energy to satisfy the stringent requirements for XFC generation. Electron beam conditioning has been performed to achieve the optimal energy spread and peak current required for high-gain EEHG operation. Preliminary tests confirm the generation of the chirped frequency-beating laser pulses with precisely controlled. Diagnostic setups for XFC characterization have been installed at the experimental hall, including a grating-based spectrometer with high spectral resolution. This experimental work paves the way for the first demonstration of fully coherent, high-power XFCs in the soft X-ray regime offering unprecedented capabilities for time-resolved spectroscopic investigations.

Speaker: Lanpeng Ni (Shanghai Institute of Applied Physics)

16:00 Experimental reconstruction of source 4D phase space without prior knowledge of transfer matrix

We use the PHOEBE test beamline at Cornell to experimentally demonstrate a simple method for reconstructing the transverse 4D phase space of an electron beam at the source from downstream aperture scans of the beam. This method does not rely on detailed knowledge of the beamline transport, besides assuming that linearity and symplecticity are satisfied. We apply this method to measure the source 4D phase space of electrons emitted from a spatially-structured alkali-antimonide cathode, and verify the fidelity of the reconstructed source spatial and momentum distributions.

Speaker: Charles Zhang (Cornell University (CLASSE))

TUP2350_edited_version.pdf

16:00 Fabrication and Radio-Frequency tests of a 1.3 GHz 9-Cell copper cavity at room temperature as a process qualification step for Niobium superconducting cavity production

The KU–KEK–KAT collaboration produced a 1.3 GHz copper 9-cell cavity with the goal of establishing a domestic Nb cavity fabrication flow in Korea, and performed pre-process verification under the same conditions as the Nb fabrication procedure. Prior to fabrication, the reliability of the actual manufacturing was enhanced through EM simulations and engineering simulations using CST, and the fabricated cavity was evaluated by measuring the resonance frequency with a network analyzer and tuning the frequency using a tuner. For this purpose, we construct new antenna by redesigning and simulating 1-cell measurement antenna to 9-cell antenna for room-temperature measurement, and all measurements were measured with this antenna. In the initial π-mode after fabrication, the resonance frequency was measured to be 1.275 GHz, which corresponds to about 90% of the design frequency of 1.3 GHz

Speaker: HeeSu Park (Kiswire Advanced Technology Ltd.)

TUP7630_edited_version.pdf

16:00 FAIR Project Management

The Facility for Antiproton and Ion Research (FAIR), currently under construction in Darmstadt, Germany, is one of the largest and most technically challenging research infrastructure projects in Europe. The project combines large-scale civil construction, complex accelerator and infrastructure systems, and scientific installations within a highly interconnected international project environment.
A key aspect of FAIR is the implementation of numerous international in-kind contributions. Accelerator and experiment components are developed, manufactured, and delivered by partner institutions from different member states. This model supports scientific collaboration, technology transfer, and the shared financing of complex infrastructure components. At the same time, it creates major organizational and technical challenges, since different engineering standards, procurement processes, national regulations, and planning cultures must be coordinated within one common project structure.
The experience from FAIR clearly shows that projects of this scale cannot be successfully realized through technical expertise alone. The large number of interdependencies between procurement, installation, commissioning activities, and scientific but also financing and regulatory requirements creates a level of complexity that can no longer be managed without the highest level of professional and integrated project management. Additional constraints and acceptance.
In this context, the FAIR Project Management Office (FAIR PMO) developed over the course of the project from a traditional reporting and controlling function into a central integration and coordination organization. Schedule planning, risk and cost management, quality management, international supplier and in-kind coordination, as well as configuration and data management, have been closely connected within one integrated management framework. A particular focus is placed on linking technical planning with risk and forecasting methods. Schedule planning, technical maturity, delivery status, resource availability, and risk developments are continuously consolidated and evaluated together. In addition, probabilistic and holistic risk and schedule assessment methods are used to represent uncertainties more realistically and to identify critical developments at an early stage. The FAIR experience also highlights the importance of clear project management structures. Methods and tools alone are not sufficient in highly complex research infrastructure projects. What is essential is the ability to identify the key main objectives and to maintain the necessary highest focus to achieve these objectives despite the technical, organizational and strategic interdependencies and complexity.
This paper describes the integrated FAIR project management approach and the role of the PMO in coordinating multidisciplinary project activities within the FAIR and GSI campus environment.

Speaker: Natalya Winters (GSI Helmholtz Centre for Heavy Ion Research, Facility for Antiproton and Ion Research)

TUP8033_edited_version.pdf

16:00 Fast Modeling of X-ray Free-Electron Laser Oscillator driven by Diffraction Limited Storage Ring

X-ray Free-Electron Laser Oscillators (XFELOs) driven by Diffraction Limited Storage Rings (DLSRs) promise ultra-narrow-bandwidth X-rays at high repetition rates. However, simulating the multi-pass laser build-up and saturation is a severe computational bottleneck. We present a simplified and highly efficient fast modeling framework for DLSR-XFELOs, which is capable of capturing power growth, temporal and spectral evolution of the radiation as well as beam quality change from pass to pass. We show the characteristic behavior of the longitudinal mode growth of such coupled system for long and short electron pulses.

Speaker: Dr Weilun Qin (Institute of High Energy Physics, Chinese Academy of Sciences)

16:00 FCC-ee Positron Capture System Based on 3 GHz RF Structures

A high-performance positron source is a crucial component of FCC-ee delivering the low-emittance, high-intensity beams. In particular, operation at the Z pole demands positron bunch charges of up to 5 nC at the Damping Ring (DR) injection. In the Feasibility Study Report, the positron source concept is based on a 2.86 GeV electron drive beam impinging on a 15 mm tungsten target. The capture section consists of a high-temperature superconducting (HTS) solenoid matching device, followed by a capture linac made of six 2 GHz travelling-wave accelerating structures embedded in a 0.5 T solenoidal channel.
In this work, we investigate a 3 GHz (S-band) RF option for the positron capture linac, taking advantage of the maturity and industrial availability of S-band technology. The study focuses on the impact of the higher RF frequency on positron capture efficiency, transverse and longitudinal beam characteristics and overall injection performance into the DR. Although the design effort is ongoing, this contribution presents the proposed 3 GHz capture layout, its main parameters and preliminary performance in comparison with the 2 GHz reference configuration.

Speaker: Yuting WANG (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

16:00 Feasibility of a Compact X-ray Free-Electron Laser Oscillator based on Diffraction Limited Storage Ring

X-ray Free-Electron Laser Oscillators (XFELOs) utilize Bragg crystal-based x-ray cavities to generate high-brightness x-ray pulses with ultra-fine bandwidth. The successful realization of XFELOs would greatly benefit high-resolution photon-hungry experiments, such as nuclear resonant scattering and inelastic x-ray scattering. Existing XFELO proposals, constrained by either the electron beam repetition rate or limited single-pass gain in the undulator, typically require long undulators and long cavities. In this work, we investigate the feasibility of a compact XFELO design, utilizing the 6-meter straight sections of a Diffraction Limited Storage Ring (DLSR) and a cavity path length well below 100 meters. We show that sufficient single-pass gain can be achieved by optimizing the undulator and electron beam parameters. We present the projected performance of the proposed scheme based on the parameters of the High Energy Photon Source (HEPS) and discuss the practical challenges associated with its implementation.

Speaker: Dr Weilun Qin (Institute of High Energy Physics, Chinese Academy of Sciences)

TUP2606_edited_version.pdf

16:00 Feasibility Study of a Demountable 6 GHz Nb₃Sn-Coated Copper SRF Cavity

Nb₃Sn (Tc ≈ 18.3 K, μ₀H_sh ≈ 400 mT) is a leading candidate for next-generation SRF cavities, and its deposition on copper offers further gains in cost and cryogenic heat load. Uniform coating and reliable adhesion on the curved inner surface of a closed cavity, however, remain a key challenge for magnetron sputtering.
A 6 GHz oxygen-free copper cavity was therefore fabricated as two half-cells split along the cavity axis, providing line-of-sight access for uniform coating and in-situ sample co-deposition. Nb₃Sn films were grown by co-sputtering from independent Nb and Sn targets, with stoichiometry tuned via the relative target power. Curved witness coupons attached to the half-cell inner surface were coated simultaneously for compositional, structural, and superconducting characterization. Under optimized conditions the films reproducibly reached Tc = 16.2 K with a narrow transition, and repeated liquid-nitrogen thermal cycling produced no peeling, delamination, or cracking.
The coated half-cells were then assembled into a complete resonator with indium-wire seals, including the stainless-steel vacuum flanges. The cavity maintained stable vacuum with no detectable leakage through multiple cool-down cycles, and the Nb₃Sn coating remained intact. These results demonstrate the feasibility of a demountable Cu cavity + Nb/Sn co-sputtering + indium-sealed assembly route at 6 GHz, and lay the groundwork for Q₀–Eacc measurements and scaling to lower-frequency cavities.

Speaker: Jiawen Kan (Institute of High Energy Physics)

16:00 Finite element studies of the CANREB electron gun for a test stand setup

The CANadian Rare isotope facility with Electron Beam
ion source (CANREB) is an important component of the
Advanced Rare IsotopE Laboratory (ARIEL) at TRIUMF.
CANREB will deliver highly charged radioactive ion (HCI)
beams for post-acceleration to nuclear physics experiments.
Ion beams injected into CANREB are bunched using a ra-
diofrequency quadrupole (RQB) cooler-buncher and energy
adjusted using a pulsed drift tube for injection into an elec-
tron beam ion source (EBIS) charge state breeder. Charge
breeding occurs by collisions with an electron beam (up
to 15 keV, 500 mA) produced by an electron gun. During
EBIS commissioning, the electron gun became unstable at
currents above 40 mA, with a large fraction of the beam
intercepted by the anode. To address this issue, an electron
gun with an updated design is planned to be fabricated and
installed in CANREB. In order to characterise the new elec-
tron gun, a test-stand will be built allowing for systematic
testing. This paper describes a full simulation model of the
test-stand using FEA software TRAK.

Speaker: Marco Hartmann (TRIUMF)

TUP2349_edited_version.pdf

16:00 First degraded beams in the CEBAF injector

The electron beam degrader in the Continuous Electron Beam Accelerator Facility (CEBAF) injector at Jefferson Lab serves to generate electron beams with transverse emittance over 10x the nominal values, with the ultimate goal of using degraded electron beams to measure machine acceptance. Electron beams are degraded through multiple scattering in thin carbon foils, and maximum transverse emittance is defined through two collimating apertures. The degrader device was installed in late 2024, with commissioning and first beams on degrader targets during the 2025 physics run. We report on first operation of the degrader device.

Speaker: Salim Ogur (Thomas Jefferson National Accelerator Facility)

TUP2331_edited_version.pdf

16:00 Fixed-Field alternating gradient transport line for laser-plasma accelerated electrons

A transport line for laser-plasma accelerated electrons is proposed based on the fixed-field alternating gradient accelerator (FFA) concept. To accommodate the large LPA energy spread and match the beam to a transverse gradient undulator (TGU), the lattice incorporates matching cells with high-temperature superconducting quadrupoles providing gradients up to 220 T/m, along with a compact FFA dispersion creator. This configuration allows strong focusing and dispersion tailoring within a compact geometry. The study represents an initial step toward demonstrating the feasibility of FFA-based dispersion management for LPA-driven light sources, while outlining the requirements of further optimization.

Speaker: Axel Bernhard (Karlsruhe Institute of Technology)

TUP3045_edited_version.pdf

16:00 Free-Electron Lasers for Large-Scale EUV Lithography

Extreme Ultraviolet (EUV) lithography has established itself as a key technology in the semiconductor chip manufacturing that supports many aspects of life in modern society. Almost all current EUV lithography tools use plasma-based light sources that deliver broad-band EUV emission from laser-irradiated molten tin droplets [1]. These standalone plasma-based EUV light sources are inefficient and not conducive to future migration to shorter wavelengths for the continuation of Moore’s law. In this paper we present an efficient and wavelength agile light source based on an energy recovery linac (ERL) driven free-electron laser (FEL). The FEL-based EUV source provides adjustable emission spectra that are much narrower than those of the plasma light sources and fit well within the narrow reflectivity curve of molybdenum-silicon multilayer mirrors. The FEL output can be adjusted to a shorter wavelength such as 6.x and 4.5 nm for future advanced lithography [2]. At these short wavelengths, photon shot noise becomes important and the FEL high photon flux capability constitutes a strong advantage over the plasma light source. More importantly, the use of superconducting RF linac in an ERL significantly increases the system wall-plug efficiency and enables multi-scanner EUV lithography. We present FEL simulations and conceptual analyses of a high-power ERL FEL that can provide multiple EUV beams simultaneously to multiple lithographic scanners in a large-scale semiconductor fab facility.

Speaker: Dinh Nguyen (xLight Incorporated)

16:00 From NbTi to Nb3Sn and 2G-HTS: Progress on Short-Period SCUs at the APS

The Advanced Photon Source (APS) continues to advance short-period superconducting undulator (SCU) technology using NbTi, Nb₃Sn, and 2G-HTS. Recent 16.5-mm-period NbTi SCUs (K ≈ 1.63) incorporate design changes to improve coil-to-ground insulation and enhanced quench protection, enabling training up to 500 A with fewer than fifteen quenches in 1.5-m magnets, ensuring reliable operation at about 430 A. Mechanical shimming reduced RMS phase errors below 5°. Eight new NbTi SCUs are planned for the APS, with two being assembled for installation in May 2026.
The first (λu=18 mm) Nb₃Sn SCU successfully delivered high-energy X-rays for three months, demonstrating suitability for user operations. Building on this, a 14-mm-period, conduction-cooled, cryogen-free Nb₃Sn SCU (K > 2) is under development using a modified cryostat. Short 0.15-m prototypes have been fabricated, are being quench trained in liquid helium, and will be tested in a small helium-free test cryostat before scaling to longer lengths.
In parallel, force-balanced 2G-HTS SCU concepts (K > 1.5) with λu ~10 mm are being explored to achieve higher magnetic fields. This presentation will highlight recent APS SCU developments.

Speaker: Ibrahim Kesgin (Argonne National Laboratory)

16:00 Function of the damper in a pulsed wire measurement system

Abstract
The pulsed-wire method (PWM) is employed for magnetic-field characterization of accelerator insertion devices. However, reflected transverse waves in PWM systems can introduce significant errors in the reconstructed magnetic-field distribution. These reflections arise because the conductor must be fixed at both ends, causing any traveling wave reaching a fixed boundary to generate a reflected component. In this study, we investigate the suppression of reflected waves using mechanically dampers integrated into the PWM setup. Experimental results demonstrate that the dampers attenuate wave reflections by more than 80%, substantially enhancing the accuracy, stability, and repeatability of the PWM measurement technique.

Speaker: Ting-Yi Chung (National Synchrotron Radiation Research Center)

16:00 Gaussian Process Regression and Bayesian Optimization for a 40-90 MeV Laser-Plasma Injector for the cSTART Storage Ring

Laser-plasma accelerators (LPAs) generate ultrashort high intensity electron bunches from a compact source size. At the Karlsruhe Institute of Technology (KIT), we will use an LPA as one of the injectors for the compact, high-momentum acceptance, non-equilibrium storage ring cSTART.

The LPA injector with a length of only a few millimeters will be optimized to match the cSTART operation beam energy of 40-90 MeV. It will be based on an ionization trapping scheme in combination with a tailored plasma density profile to produce an electron beam with small energy spread that maximizes the spectral charge density at our target energy, which is (for LPAs) comparably low. Moreover, the LPA injector must produce controlled electron beams with high shot-to-shot stability and avoid high-energy tails. These goals can be achieved largely by the detailed design of the plasma density profile and the laser pulse parameters.

In an LPA, small changes across the high-dimensional parameter space can have a disproportional influence on overall performance. To find parameters for stable high-quality LPA beams, we perform particle-in-cell (PIC) simulations and implement a machine-learning driven approach by using Bayesian Optimization (BO) based on Gaussian Process Regression (GPR). This procedure allows us to both optimize our gas target design and characterize the effects of the interaction parameters, giving us a functional LPA with a simple tuning mechanism.

Speaker: David Squires (Karlsruhe Institute of Technology)

TUP3044_edited_version.pdf

16:00 Generation and diagnostics of nanosecond-interval laser pulse trains with femtosecond-level timing control for the Korea-4GSR photocathode RF gun

The Korea-4GSR (4th Generation Storage Ring) requires a highly stable and precisely synchronized laser pulse train to drive its photocathode RF gun in multi-bunch mode. To meet this requirement, we developed a laser system capable of generating nanosecond-interval pulse trains with femtosecond-level timing control. The pulse train is formed using a beam-split/delay-and-combine method, producing a 64-pulse sequence with 2 ns separation, synchronized to a 500 MHz RF reference.
To further enhance synchronization accuracy and diagnose timing jitter at the femtosecond scale, a 500 MHz femtosecond oscillator is being developed and integrated into the system. This fs-oscillator enables precise timing diagnostics, long-term drift monitoring, and improved stability for multi-bunch operation. The combined system is designed to provide low-emittance, low-energy-spread electron bunches required for Korea-4GSR’s high-brightness injector and ensures reliable operation in both single-shot and multi-bunch modes.

Speaker: Namseok Go (Pohang Accelerator Laboratory)

TUP2629_edited_version.pdf

16:00 GPU-Accelerated simulation framework for partially coherent EUV light transport in Tsinghua SSMB beamline optics

Accurate simulation of partially coherent beam transport and coherence evolution is critical for next-generation accelerator-based light sources. In this work, we develop a dedicated numerical approach for partially coherent EUV beamline propagation to support the optical design and optimization of Steady-State Microbunching (SSMB) beamlines under development at Tsinghua University.* A GPU-accelerated mutual optical intensity framework is developed for two-dimensional propagation of partially coherent radiation. Using spatially partitioned diffraction-integral kernels with locally reconstructed paraxial approximation, the method achieves substantial speedup over conventional mutual-intensity and wavefront-based propagation methods while maintaining high accuracy. Complex optical components, including arbitrary curved and rough reflective surfaces, are fully supported for efficient simulation of realistic EUV systems. In summary, the proposed framework provides a practical tool for optical design and end-to-end simulation of EUV beamlines, enabling coherence analysis and accurate light propagation modeling of partially coherent radiation.

Speaker: Mr Haowei Hu (Tsinghua University)

TUP2714_edited_version.pdf

16:00 Ground-state and RF-frequency scaling for superconducting quantum systems

A fixed-volume comparison of three-dimensional hard-wall quantum confinement is extended to a volume-dependent frequency model for superconducting quantum systems. The equivalent quantum frequency is obtained from the lowest Dirichlet eigenvalue and compared with radio-frequency (RF) scales used in supercon-ducting radio-frequency (SRF) cavities. The calculation separates the Schrödinger confinement scale from the electromagnetic wavelength scale: the quantum frequency follows an inverse two-thirds volume law, whereas a dimensional RF half-wave scale based on L = V¹ᐟ³ follows an inverse one-third volume law. Equating the two frequencies maps MHz-to-GHz SRF operation to submicron-to-micron local confinement lengths, supporting applications to superconducting islands, surface defects, qua-siparticle traps, and cavity-integrated quantum devices.cavity systems.

Speaker: Juwan Kim (Institute for Basic Science)

TUP7641_edited_version.pdf

16:00 High current accelerator-driven neutron source platform overview

ESS-Bilbao, JCNS, and LLB joined forces to develop Europe’s first HICANS  Platform (HiCANS stands for "High Current Accelerator-driven Neutron Source"). This project aims to integrate the high current proton accelerator system, currently under construction at ESS Bilbao, with the target-moderator-reflector unit that has been successfully built and operated at Forschungszentrum Jülich, and the HERMES reflectometer and Be target owned by LLB. This facility intends to validate and demonstrate the technological developments that will take part of these medium-flux neutron sources. 

In this demonstrator, the first stage of the ARGITU source will be used to produce a pulsed proton beam with an energy of 3 MeV and a period of 30 Hz to hit a Lithium target, generating neutrons that are moderated at the desired thermal and cold energy ranges that will be utilized by the HERMES neutron reflectometer. 

The instrument has undergone upgrades and improvements, since it was first installed in the COSY platform, such as the installation of a methane moderator, which has increased the reflectivity signal by a factor of two. The installation of the instrument in ESS-Bilbao premises will help to continue its experimental program, as well as paving the way to future integration of neutron scattering and imaging instruments at higher accelerator power.

Speaker: Ibon Bustinduy (ESS Bilbao)

TUP3079_edited_version.pdf

16:00 High electron charge accelerated in the SM-LWFA regime with the LMJ-PETAL laser

Sources of energetic electrons accelerated by ultra-intense lasers have diverse applications across various research fields. This presentation details recent numerical and experimental findings on electron acceleration using the ~0.7 kJ, ~0.7 ps LMJ-PETAL laser system. Due to the long pulse duration, the interaction of the PETAL beam with a gas jet (~cm in length) accelerates electrons in the self-modulated laser wakefield acceleration (SM-LWFA) regime. Experimentally, electron energies up to 300 MeV have been achieved, exhibiting an exponentially decreasing spectrum and a substantial divergence (~100 mrad), consistent with the SM-LWFA regime. Notably, the high laser energy results in a very high charge, in the microcoulomb range, which presents promising prospects for novel applications. Multidimensional particle-in-cell (PIC) simulations, conducted using the Calder and Osiris codes, corroborate these findings. The simulations demonstrate laser self-focusing and self-modulation, along with electron acceleration in the wakefield. While direct laser acceleration (DLA) is also observed, it does not appear to be the dominant mechanism in this configuration.
Overall, these results, characterized by a broad spectrum but with a very high charge, offer promising avenues for new applications of LWFA in kJ and ps-class laser facilities, such as generation of intense secondary neutron sources or electron-positron pair jets.

Speaker: Xavier Davoine (CEA DAM Île-de-France, Laboratoire Matière en Condition Extrêmes)

16:00 High Gradient Testing of a Two-Cell C-band Accelerator Cavity with NiCr Higher-Order Mode Absorbers

This presentation will report on the status of fabrication, tuning, and high gradient testing of a two-cell accelerator cavity with distributed coupling and higher-order-mode (HOM) damping slots covered with nickel-chromium (NiCr) absorbing material. The cavity is designed with a specific purpose to demonstrate applicability of NiCr material for damping HOMs in a C-band distributed-coupling accelerating structure, such as may be used in a C3 linear collider. The purpose of this experiment is to conduct a simple high-power test to understand fabrication challenges for the cavity with NiCr HOM absorbers and examine performance of the NiCr coating during high power conditioning. We will report the detailed electromagnetic and engineering design of the cavity, fabrication, cold testing, tuning and the results of high gradient testing at the CERF-NM C-band high gradient test facility at Los Alamos National Laboratory.

Speaker: Evgenya Simakov (Los Alamos National Laboratory)

TUP7313_edited_version.pdf

16:00 High power GaN amplifier development for coupled-cavity Linac at LANSCE

The Los Alamos Neutron Science Center uses a coupled-cavity linac to accelerate H- ions from 100 to 800 MeV. It is powered by forty-four 1.25 MW 805 MHz klystrons, each capable of 150 kW of average power. A prototype solid-state amplifier that meets these requirements is in development. Commercial silicon LDMOS transistors have reduced power above 600 MHz and are also limited by the maximum drain to source breakdown voltage. We are using high voltage Gallium Nitride (GaN) on Silicon Carbide (SiC) high electron mobility transistors (HEMT) to reduce the number of active devices and the complexity of power combing smaller amplifiers. These wide bandgap semiconductors can operate at high channel temperatures around 200 degC without shortened life. We are testing new devices up 5 kW of peak power at 100 volts. Operating in saturation mode, outphasing modulation is used to maintain high device efficiency to reduce thermal dissipation, compared to conventional class AB linear amplifiers. The power supply requires stored energy with a capacitor bank. Power combining uses a combination of 2-way Gysel, 40-way radial and magic tee combiners in waveguide.

Speaker: John Lyles (Los Alamos National Laboratory)

TUP7347_edited_version.pdf

16:00 High power tests of a high-efficiency C-band traveling-wave accelerating structure

In order to realize a compact scheme and high accelerating efficiency for the linear injector of the proposed Jinhua light source (JHLS) project, a 1-meter constant gradient (CG) C-band traveling-wave (TW) accelerating structure has been developed and constructed to achieve a high acceleration gradient of > 50 MV/m. This C-band accelerating structure operates at 3π/4 mode and achieves an average shunt impedance of 94 MΩ/m through optimization. After tuning process, the cold-test measurement results of this accelerating structure are in good agreement with the simulated values. In high-power tests, this structure was fed into an average power of 32 MW(equivalent to an output power of 37.7 MW from the klystron) with a pulse width of 300 ns. Therefore, an unloaded gradient of 41.6 MV/m was achieved at a breakdown rate of less than 1 × 10−5 breakdown per pulse meter (bppm). A further high-power tests are expected to achieve an average gradient of > 50 MV/m in the next step.

Speaker: Zexin Cao (University of Science and Technology of China)

TUP7612_edited_version.pdf

16:00 High Reliability Digital Control Magnet Power Supply System for SPring-8-II

We have developed new magnet power supply (PS) system for the forthcoming green light source facility, SPring-8-II. Aiming at highly reliable and energy conscious accelerator operations, various PSs with a variety of output current and voltage settings are designed such that (i) each PS with an output current larger than 250 A includes Silicon Carbide switching devices, achieving a conversion efficiency larger than 93% (ii) all PS are embedded with a full digital control system that enables a versatile individual parameter setting, and (iii) main PSs are connected in series to multipole magnets for suppressing PS failures as low as possible. For an individual current setting for the correction of betatron beatings and other purposes, we will prepare auxiliary PSs to add to each individual magnet where it is required. Bipolar PSs for steering magnets have been designed to provide stable output over the whole current range by optimizing our pulse width modulation control. Additionally, we have proposed a new option to adjust an individual current setting by implementing shunt resistors, and also a fast PS switcher that can quickly replace a failed PS with a backup PS without a beam loss is being prepared. We will present these new PS designs and the results of our demonstrations.

Speaker: Chikara Kondo (Japan Synchrotron Radiation Research Institute, RIKEN SPring-8 Center)

TUV7601_edited_version.pdf

16:00 High-charge and high-brightness beam generation at the Advanced Photon Source photoinjector

The recent installation of a new photocathode drive laser has significantly improved the reliability of photoinjector operations at the Advanced Photon Source (APS), Argonne National Laboratory. The photoinjector can operate in either high-charge or high-brightness mode. The high-charge mode is ultimately intended to support direct injection from the linac into the booster ring, eliminating the need for charge accumulation performed in the Particle Accumulator Ring (PAR). In contrast, the high-brightness mode optimizes the photoemission source to produce bright, compressed electron bunches that can be delivered to the Linac Extension Area (LEA) for accelerator R&D. This paper discusses the design considerations and initial commissioning results of the photoinjector with the new laser system.

Speaker: Yine Sun (Argonne National Laboratory)

TUP2329_edited_version.pdf

16:00 High-efficiency neutron transport using magnetic gradient with permanent magnets

Neutron guide tubes are used to transport neutrons efficiently. However, it requires very precise alignment, which is costly and vulnerable to shocks from earthquakes and other incident. It also is very sensitive to the surface condition such as cracks or dusts on the mirror. We are developing a new type of neutron mirror by utilizing the deflection of neutrons in a gradient magnetic field. This paper presents experimental results obtained using neutron beams at SOFIA (MLF).

Speaker: Dr Yoshihisa Iwashita (The University of Osaka)

TUP7726_edited_version.pdf

16:00 High-Frequency THz Generation and Compact High-Gradient THz-Driven Accelerator with Tapered Parallel-Plate Waveguide.

The relatively new sub-field of dielectric terahertz-driven accelerators (DTAs), which combines terahertz (THz) technology with dielectric laser accelerators, has gained relevance in recent years. To achieve high acceleration gradients, high-intensity THz fields are required. Therefore, high-gradient DTAs encompass the design of compact, high-intensity THz pulse sources.

In this work, we present two important elements for a compact, high-gradient accelerator: 1) A high-frequency THz source based on periodically-inverted crystals pumped with an ultra-short infrared pulse with a central wavelength of 1.8 µm, and 2) An innovative DTA that incorporates a dual-pillar grating arrangement within a tapered parallel-plate waveguide (TPPWG). This compact configuration enables particle acceleration via few-cycle terahertz pulses.

High-frequency THz pulses in QPM crystals are explored by optimizing pump duration, intensity, and pumping scheme to maximize the optical-to-terahertz conversion efficiency, enabling THz pulses up to 4 THz and beyond. Time-domain simulations on the TPPWG indicate that optimizing the waveguide parameters results in a sixfold increase in peak electric-field amplification at the waveguide end. Particle-in-cell (PIC) simulations demonstrate that the structure supports net acceleration with gradients up to 120 MeV m-1 for 0.1 GV m-1 field strengths, and can accommodate bunch charges up to 10 pC with minimal degradation.

Speaker: Andres Leiva Genre (University of Pecs)

16:00 High-power amplifier considerations for testing the LAMP RFQ and first DTL cavity

As part of the LANSCE Accelerator Modernization Project (LAMP), critical portions of the proposed accelerator will be tested as proof of concept and aid in planning the installation of LAMP at Los Alamos Neutron Science Center. As part of this demonstration, the radio frequency quadrupole (RFQ) and the first drift-tube linac (DTL) cavity will be tested with beam. For this purpose, high-power RF amplifiers are being designed to meet the testing demands. This is a description of the requirements of these amplifiers and how the design is intended to meet them.

Speaker: Maria Sanchez Barrueta (Los Alamos National Laboratory)

TUP7346_edited_version.pdf

16:00 High-power experimental study on a compact C-band spherical pulse compressor

In order to enhance the accelerating gradient of the 1-meter C-band Traveling-wave accelerating structure prototype, as well as meet the physics requirements on the linear injector of the proposed Jinhua light source (JHLS) project, a compact C-band spherical pulse compressor was developed to boost the output power from klystron. This pulse compressor excites TE114 modes inside the spherical cavity by coupling energy via a compact polarized coupler. In the preliminary high-power conditioning, an output pulse of 8.7 MW, 2.6 μs from the klystron was compressed to 53.9 MW, 400 ns pulse through this pulse compressor, thereby enabling an average power gain of 4.2. An amplitude modulation approach was adopted to generate a flattop output pulse, an average power gain of 3.78 with a full-width at half-maximum (FWHM) pulse duration of 353 ns was achieved after modulation.

Speaker: Zexin Cao (University of Science and Technology of China)

TUP7611_edited_version.pdf

16:00 High-power testing of X-Band high-gradient structures and RF components at the Mel-BOX facility

Mel-BOX, the reinstallation of half of CERN’s XBOX3 test stand, has been operating at the University of Melbourne’s X-LAB for over few years. The facility provides 12 GHz high-power pulsed RF for testing high-gradient travelling-wave accelerating structures and associated X-band components relevant to the CLIC baseline.
Two TD24 structures, previously conditioned at CERN and stored for five years, were successfully reconditioned and tested at Mel-BOX, demonstrating that prolonged storage does not significantly degrade high-gradient performance. Additional high-power RF campaigns were carried out on a compact pillbox-type RF window supporting travelling-wave fields in the ceramic, high-power loads fabricated using 3D-printed titanium and long stainless-steel sections, and a set of SLED-I pulse compressors featuring a newly designed removable copper tuning plate. Each pulse-compressor cavity was independently tuned prior to conditioning, enabling stable operation and reproducible pulse compression during high-power tests.
These activities establish Mel-BOX as a dedicated and mature X-band platform for advancing high-gradient accelerator technology and supporting the development of compact accelerator systems for medical, industrial, and scientific applications.

Speakers: Joel Valerian (The University of Melbourne), Matteo Volpi (The University of Melbourne)

TUP7602_edited_version.pdf

16:00 High-precision current feedback control of a MHz kicker magnet system for the SHINE

A kicker magnet system is under development for the Shanghai High repetition rate X-ray Free Electron Laser and Extreme Light Facility (SHINE) at the Shanghai Advanced Research Institute, Chinese Academy of Sciences (SARI, CAS). Mitigating thermal drift during extended operation is essential to maintain the beam distribution stability. A high-precision current feedback control system has been designed to regulate the kicker power supply at 1 MHz with an amplitude stability below 100 ppm. The system integrates a differential amplification circuit using a low-thermal-coefficient resistor network for real-time drift compensation, together with a proportional–integral–derivative (PID) control operating at a response time of ~100 ms to stabilize the output current. This approach supports current measurement resolution on the order of ~10 ppm. Under1 MHz pulsed operation, the experimental results achieve a pulse-to-pulse amplitude stability of 63.7 ppm over 30 minutes with closed-loop feedback, and maintain stability within 150 ppm after 8 hours of continuous running. The design, implementation, and tested performance of the system are reported and discussed.

Speaker: Dr Sheying LI (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

TUP7708_edited_version.pdf

16:00 High-Precision PCB-Based Rotating Coil System for Multipole Magnet Measurements in the 4GSR Storage Ring

For the reduction of beam emittance in a Korea-4GSR project, the storage ring will be equipped with 344 quadrupole, 168 sextupole, and 56 octupole magnets. These multipole magnets require precise magnetic measurements to verify not only the field strength but also harmonic components within the specified tolerances over a good field region with a diameter of 30 mm. To meet this requirement, a PCB-based rotating coil measurement system has been developed. The PCB consists of a 14-layer multilayer structure incorporating both main and bucking coils, enabling high-precision measurement of allowed and higher-order harmonic components. The PCB length was designed to be 660 mm, considering to the effective magnetic length of the 4GSR multipole magnets. To minimize mechanical sag, the rotating shaft was fabricated from ceramic material and positioned at the magnetic field center using a high-precision XY stage with 0.1 μm resolution. The developed rotating coil system achieves a measurement precision better than 5 × 10-4, demonstrating its suitability for high-accuracy characterization of small-aperture multipole magnets in the 4GSR project.

Speaker: Dr Yoon Geol Choi (Pohang University of Science and Technology)

TUP7722_edited_version.pdf

16:00 Higher Order Modes Measurement Surveys for Newly Installed CEBAF C100 and C75 Cryomodules

The Higher Order Modes (HOMs) on each of 8 Superconducting Radio Frequency (SRF) cavities have been measured as the result of surveys on newly installed C100 and C75 cryomodules at the CMTF cave and the CEBAF tunnel during their commissioning. We are going to report the measurement, data analysis techniques and the result against its HOM damping specification for the multi-turn dipole Beam Break-Up (BBU) threshold of ~400uA, CW electron beam current runs for the CEBAF nuclear physics experiments.

Speaker: Neil Stilin (Thomas Jefferson National Accelerator Facility)

16:00 Impact of VPU on beam dynamics in the SIRIUS storage ring

This work evaluates the effects of the first vertical polarization undulators (VPUs) installed in the SIRIUS storage ring on electron-beam dynamics. These insertion devices (IDs) are light sources for the CARNAÚBA and CATERETÊ beamlines at the Brazilian Synchrotron Light Laboratory (LNLS). The analysis combines numerical simulations and beam-based measurements to quantify static and dynamic orbit distortions, optics perturbations (beta-beating and tune shifts), effects on injection efficiency, and changes in equilibrium beam parameters, including beam lifetime. The effectiveness of ID feed-forward compensation in mitigating these effects is assessed. Results characterize the operational impact of the VPUs on storage ring performance, providing safe conditions for beamline operation.

Speaker: Gabriel Ascenção (Brazilian Synchrotron Light Laboratory)

TUP2338_edited_version.pdf

16:00 Implementation of a Dual-Pulse UV Laser System for Two-Bunch Mode at PAL-XFEL

PAL-XFEL is preparing for a two-bunch operation, in which two electron bunches separated by 25 ns are accelerated within a single RF field. This mode enables simultaneous 60 Hz operation for two beamlines without the need for additional accelerating structures. To support this operation, a UV laser system capable of generating two temporally separated pulses was developed. The system utilizes an in-line third-harmonic generation (THG) setup with optical delay lines and polarization-based beam splitting to produce two UV pulses with a 25 ns separation. The measured pulse energies were approximately 120 µJ after generation, 70 µJ after polarization filtering, and 20 µJ at the RF gun entrance. These developments constitute a critical step toward multi-bunch, multi-beamline operation at PAL-XFEL, enhancing facility efficiency and enabling simultaneous user experiments.

Speaker: Seong-Hoon Kwon (Pohang Accelerator Laboratory)

16:00 Improvement and optimization of a permanent-magnet phase shifter

A permanent-magnet (PM) phase shifter for phase matching between tandem elliptically polarizing undulators (EPUs) at the Taiwan Photon Source (TPS) has been developed, and its initial version has already been installed in the storage ring. Current efforts focus on improving the device by enhancing the mechanical precision of the gap-adjustment system, maintaining magnetic-field quality, and minimizing beam-orbit perturbations within the limited installation space. Magnet sorting and shimming techniques were used to refine the magnetic performance of the first version.

At small operating gaps, strong magnetic forces introduce substantial mechanical loading and can affect the field directionality. To overcome this limitation, an upgraded design incorporating a spring-assisted mechanism is under development. This work presents the optimization approach and the resulting improvements achieved through the integration of the spring system, demonstrating enhanced structural stability and improved reproducibility under high-force operating conditions.

Speaker: Chin-Kang Yang (National Synchrotron Radiation Research Center)

TUP7704_edited_version.pdf

16:00 Influence of current excitation profiles on screening-current effects in REBCO bending magnets for the Hefei advanced light facility

ReBCO coated conductors are promising for compact high-field bending magnets and are being considered for use in the Hefei Advanced Light Facility (HALF) to enhance the photon energy from bending-magnet radiation. However, screening-current effects induced during excitation remain an important issue for such magnets. In this work, these effects are investigated in the proposed bending magnet using the H-formulation. Several current excitation profiles with different ramping and holding stages are compared. The results show that the charging history strongly affects screening-current relaxation and the induced-field distribution. Under the present conditions, final holding at the operating current is more effective than a slow final ramp or distributed intermediate holding, providing guidance for optimizing charging schemes for future ReBCO bending magnets.

Speaker: Jincheng Xia (University of Science and Technology of China)

TUP7656_edited_version.pdf

16:00 Innovative Radioactive Ion Beam Production for MORA at GANIL

The MORA experiment is looking for a possible signature for CP violation in the decay of radioactive trapped and polarised ions [1]. The two main candidates for measurements at MORA are 23Mg+ and 39Ca+, that will be delivered by the SPIRAL 1 facility in GANIL as of 2029.
The 39Ca+ beam requires a challenging development. To achieve a sufficient beam intensity - more that 1E7 pps - the innovative TULIP target ion source system [2] will be coupled to a fragmentation target.
This contribution will present the current status of this development and the broader, potentially unique beam-intensity opportunities it enables for future experiments at SPIRAL1 using exotic radioactive ion beams.

This project is supported by ANR under contract ANR-25-CE31-4222.
References:
[1]: P. Delahaye et al., The MORA project, Hyp. Int. 240, 63 (2019).
[2]: P. Jardin et al., «Sub-millisecond atom-to-ion transformation in the TULIP ISOL system,» Nucl. Instrum. Meth. A, vol. 1055, p. 168332, 2023.

Speakers: Dr Pascal Jardin (Grand Accélérateur National d'Ions Lourds), Dr Pierre Chauveau (Grand Accélérateur National d'Ions Lourds), Pierre Delahaye (Grand Accélérateur National d'Ions Lourds)

16:00 Insertion devices for SPring-8-II

In the SPring-8-II project, a major upgrade of the synchrotron radiation facility SPring-8, numerous insertion devices (IDs) will be replaced by new ones such as the standard/tapered in-vacuum undulators for SPring-8-II (IVU-II) for hard x-rays, the helical 8 undulators for soft x-rays with variable polarizations, and damping wigglers for emittance control. Among these, the standard IVU-II will account for the majority, with about 30 units scheduled for installation. Mass production is underway, installation into the existing SPring-8 beamlines is also in progress, and several IVU-IIs are already under user operation. In this report, we will introduce the features of the new IDs listed above.
In addition to the unique magnetic circuit for force cancelation, the modularization of magnetic arrays employed in the IVU-II simplifies the assembly process of the magnetic arrays. With an assembly time much shorter than that for the previous IVU, the IVU-II meets the stringent specification required for SPring-8-II. In this presentation, the distinctive magnetic field tuning method of IVU-II will also be introduced, together with the measured results on the magnetic field performance of the developed IVU-II.

Speaker: Yuichiro Kida (Japan Synchrotron Radiation Research Institute)

16:00 Installation and startup of an 18 GHz ECRIS for highly charged metallic ions and gases

This paper presents the technical improvements and experimental
characterisation of a hybrid superconducting 18\,GHz Electron Cyclotron Resonance Ion Source
(ECRIS) manufactured by Pantechnik. Since the last one manufactured in 2011, the source has undergone significant upgrades to enhance its performance and reliability for heavy ion beam production. Key improvements include optimisation of the magnetic confinement system, aiming to increase the production of highly charged
ions while maintaining stable operation at high RF power levels. An extensive experimental campaign is currently underway at Pantechnik's facilities to characterise the source performance on a selection of ions (N, Al, Ar, Au, Pb) and the goal of demonstrating stable
Xe$^{28+}$ and Ta$^{36+}$ beams.

Speaker: Ambra Morana (Pantechnik)

TUP3067_edited_version.pdf

16:00 Installation qualification of the semi-industrial Circe III e-beam accelerator

This work details the qualification of a semi-industrial 10 MeV, 5 kW pulsed electron Linear Accelerator (Linac) facility, following critical maintenance on the modulator. The accelerator operates using a thermoionic emission source and a traveling-wave accelerating structure. The maintenance involved replacing a damaged Pulse Forming Network (PFN) component.
The objective of this qualification process was to verify that the accelerator system meets its original operational specifications and performance parameters after the critical intervention, to ensure the stability, reliability, and dose delivery accuracy of the electron beam for its intended applications, which are typically the sterilization of medical devices.

Speaker: Mohamed Hedi TRABELSI (CNSTN)

16:00 Integrated Sustainment Strategy through a Unified Accelerator Systems Definition

The sustained reliability and availability of the LANSCE accelerator depend on a clearly defined and integrated “systems” framework. This foundation links five core sustainment strategies: Asset Management, Risk Management, Conduct of Engineering, Training & Qualification, and Data Collection & Analysis. Unifying these under a common structure enables consistent decision-making, coordinated resource use, prioritized maintenance, and system-level performance tracking. It breaks down silos, improves efficiency, and supports targeted workforce development while reinforcing clarity in roles, responsibilities, authority, and accountability. Realizing this vision requires deliberate planning, early stakeholder engagement, and a robust change management strategy to navigate organizational and cultural shifts. This unified framework bridges short-term needs with long-term goals, positioning LANSCE to sustain mission-critical operations through 2050 and beyond. The paper explores this integrated approach as a scalable model for other aging accelerator facilities seeking sustainment without compromising mission continuity.

Speaker: Martin Pieck (Los Alamos National Laboratory)

TUP8304_edited_version.pdf

16:00 Intense and Tunable Multi-color Terahertz Radiation from Laser-Shaped Electron Beams

High-power multi-color terahertz (THz) radiation exhibits extraordinary scientific application prospects at various scientific frontiers, for its capacity to deliver THz excitation at multiple frequencies simultaneously. However, the generation of high-power multi-color THz radiation with tunable frequencies remains a challenge for existing techniques. Here, a technique by combining the multi-laser pulses frequency beating and coherent undulator amplification is proposed for generating high-power multi-color THz radiation with tunable frequency. Numerical simulations indicate that the proposed technique can produce multi-color THz radiation with three to six distinguished colors and a peak power up to hundreds of MW, and the temporally separated two-color pulses can also be produced by employing undulators with different resonance. Due to the intrinsic properties of the proposed technique, the THz frequencies, the color number and the frequency interval can be effectively controlled by simply adjusting the beating laser. This method paves the way for advanced application of THz pump-THz probe experiments for selective excitation of atomic multi-level systems and molecular fingerprint recognition.

Speaker: Yin Kang (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

16:00 Interaction of high-intensity beam with structured solid surface plasma for wakefield acceleration and coherent radiation generation

Recent research into the interaction between high-intensity beams and surface plasmas has revealed the significant potential of generating extremely strong (~TV/m) fields for particle acceleration and radiation production. This new approach has emerged by overcoming several challenges in beam-solid interactions. It therefore holds great promise for reshaping the research direction of large-scale facilities pursuing the energy frontier and micro-scale facilities requiring great flexibility. At the same time, this research can provide new insights into the extremely complex nonlinear dynamics of surface plasmons (SPs) in strong fields and a new, unexplored regime of plasma-based particle acceleration.

In this study, we theoretically investigate the high-intensity laser- or beam-driven excitation of relativistic surface plasmons on the micro-scaled surfaces of structured nanomaterials, such as vertically aligned carbon nanotube (VACNT) forests. Leaky and bubble wakefields can be generated with amplitudes exceeding 400 TV/m and high energy efficiency for both electron and positron acceleration. By investigating SP mode selection on cylindrical surfaces, we have proposed a new principle for coherent radiation generation that differs fundamentally from traditional superradiance. Our research offers a new approach to the development of ultrahigh-gradient and ultra-compact particle accelerators, which could transform medicine and materials science.

Speaker: Prof. Carsten Welsch (University of Liverpool, Cockcroft Institute)

TUP3014_edited_version.pdf

16:00 Investigation and diagnostic potential of off-axis resonance in THz Free-Electron Lasers

We study undulator radiation observed away from the beam axis for terahertz (THz) free-electron laser (FEL) beams. Earlier work on a single short bunch relates the continuous off-axis spectrum to the longitudinal bunch profile , without a discrete angular ‘resonance’ tied to micro-bunch harmonics. For a pre-bunched pulse-train beam, the bunching factor develops narrow spectral lines at the fundamental frequency and its integer harmonics. Off-axis phase matching selects a specific resonant polar angle for each line, producing pronounced, spatially separated ring-like intensity patterns in the coherent far field. We utilize the non-averaged 3D FEL code PUFFIN to simulate single-bunch radiation—reproducing non-integer harmonic patterns consistent with analytical Lié-nard-Wiechert (LW) results—and to demonstrate the expected off-axis resonance for pulse-train beams.

Speaker: Tong Li (Tsinghua University)

TUP2686_edited_version.pdf

16:00 Investigation of outgassing properties of CuZr and CuCrZr vacuum pipes

The Hefei Advanced Light Facility (HALF) is the fourth-generation synchrotron radiation light source based on Diffraction-limited Storage Ring (DLSR) with low beam emittance, high brightness and coherent photon flux. According to the physical design re-quirements of the HALF, the vacuum chamber struc-tural materials should have low outgassing rate, good electrical and thermal conductivity, high strength, and non-magnetic. CuZr and CuCrZr were selected as structural materials for the HALF storage ring vacuum chamber structural materials, taking into account ma-terial properties and manufacturing process. In this paper, thermal outgassing performances of CuZr and CuCrZr alloy pipes under temperature rise was inves-tigated for the design and calculation of HALF vacuum systems.

Speaker: Tianlong He (University of Science and Technology of China)

THP3001_edited_version.pdf

THP3001_edited_version.pdf

THP3001_edited_version.pdf

THP3001_edited_version.pdf

THP3001_edited_version.pdf

TUP7687_edited_version.pdf

16:00 Investigation of RF surface resistance in Sub-GHz superconducting elliptical cavities processed with various nitrogen-doping surface treatments

Superconducting radio-frequency (SRF) cavity surface treatment with nitrogen-doping (N-doping) was a breakthrough in cavity processing which was found capable of increasing the cavity quality factor (Q0) by more than a factor of 2 compared to standard electropolish (EP) surface treatments, as well as achieving a highly desirable anti-Q slope behavior, an increase of Q0 with increasing accelerating field, in 1.3 GHz superconducting niobium cavities. N-doping has been extensively studied in 1.3 GHz cavities; however, a similarly significant increase in performance had not yet been observed in sub-GHz cavities. In this study, field-dependent BCS and residual resistances were measured in 644 MHz cavities for the FRIB energy upgrade with various surface treatments. The frequency dependence of the Q-slope was investigated by measuring BCS and residual resistances in the fundamental mode (FM) and 1.45 GHz higher-order mode (HOM) in the same cavity. We will report effects of various N-doping surface treatments on the FM and HOM performance, including achievements of Q0 as high as 4.9x10^10 at 17.5 MV/m in this class of SRF cavities.

Speaker: Sean Moskaitis (Facility for Rare Isotope Beams)

TUP7326_edited_version.pdf

16:00 Investigation on the vacuum properties of Al-TiZrV bilayer films

Maintaining an ultra-high vacuum (UHV) environment is essential for the Hefei Advanced Light Facility (HALF) to achieve its design performance. Owing to the dimensional limitations imposed by small-aperture vacuum chambers, non-evaporable getter (NEG) films are commonly applied to the inner walls to enhance vacuum performance. However, conventional NEG films increase the resistive-wall impedance of the vacuum pipes, there-by exacerbating the wakefield effects. To address this problem, a novel composite film, Al-TiZrV, has been developed. By covering the TiZrV film surface with a highly conductive film, it can reduce the resistivity of the composite film. The results show that while the addition of the Al layer reduces the resistivity significantly, it increases the secondary electron yield (SEY), exacerbating the electron cloud effect. This study provides insights into the complex properties of similar bilayer films for future research on accelerator-related materials.

Speaker: Xinyu Jin (University of Science and Technology of China)

16:00 Investigation to mitigate the transient beam-loading effect using the broadband kicker cavity

Bunch lengthening technique is most reliable method to mitigate the intrabeam scattering in synchrotron light sources. The performance of the bunch lengthening can be degraded by a transient beam-loading (TBL) effect, which becomes large when long gaps are introduced in the bunch filling pattern. To mitigate the TBL effect, we have proposed a compensation method using a broadband cavity [1]. We have investigated the conceptual design of the kicker cavity and carried out the performance tests of the low-power model cavity that can be used to compensate for the TBL effect [2]. In this presentation, details and further discussions about the performance of the TBL compensation will be reported based on the results of the performance tests and semianalytical calculation. As an example, the TBL compensation at the KEK PF 2.5 GeV ring is investigated using semianalytical calculations. The strategy of the TBL compensation at the PF ring is discussed. The performance of the TBL compensation using the kicker cavity is investigated.
[1] N. Yamamoto et al, Phys. Rev. Accel. Beams 21, 012001 (2018)
[2] D. Naito et al, Phys. Rev. Accel. Beams 28, 112002 (2025)

Speaker: Naoto Yamamoto (High Energy Accelerator Research Organization)

TUP2680_edited_version.pdf

16:00 Joint Development of Superferric Corrector Magnets for HL-LHC

The HL-LHC project is a major upgrade of CERN’s LHC, aiming to enhance the collider’s integrated luminosity by a factor ten within ten operational years. Endorsed as top priority for the European Strategy for Particle Physics in 2013, the project was formally approved by CERN’s Council in 2015.
To achieve its performance goal, HL-LHC relies on several technology drivers. Among the new magnets for the interaction regions, the superferric – named so, because they combine superconducting NbTi coils with iron pole pieces to enhance the magnetic field near the aperture – high-order mode correctors are key in ensuring beam quality and stability, correcting field errors and compensating non-linearities in the magnet lattice. These magnets were the object of a collaboration between CERN and INFN-LASA Milan, first joint project to deliver its full scope to HL-LHC. INFN-LASA was tasked with design, prototyping, and industrialization. Key to the delivery of 54 correctors by 2023 was the early initiation via the INFN MAGIX project, followed by two agreements for prototyping and series production. The collaboration spanned over a decade and benefited from the early involvement of the industrial partner SAES-RIAL.
The paper reviews the collaboration, detailing cost structure, schedule adherence, and industrialization process. Focus is on key factors that contributed to the success of the collaboration and lessons applicable to large-scale partnerships for future accelerator projects.

Speaker: Giovanna Vandoni (European Organization for Nuclear Research)

TUP8031_edited_version.pdf

16:00 Key Technologies for the Vacuum System of the High Intensity Heavy Ion Accelerator Facility

The vacuum system of the High Intensity heavy ion Accelerator Facility (HIAF) is critical for stable high-intensity beam transport and long-term reliable operation. This system, which spans 2 kilometers, faces numerous technical challenges. To reduce eddy current effects caused by rapidly changing magnetic fields, the Booster Ring (BRing) adopts an innovative titanium alloy-lined ultra-thin-walled (0.3 mm) vacuum chamber, combining 3D printing with Non-Evaporable Getter (NEG) coating technology. This chamber type constitutes 60% of the BRing. Through optimized outgassing processes and built-in component structures, an average pressure of 4.66 × $10^{-10}$ Pa was achieved, making it the world’s largest room-temperature ultra-thin-walled vacuum system. For the Spectrometer Ring (SRing) electron cooling system, limited installation space led to an integrated solution combining sputter ion pumps, built-in titanium wire evaporation, and NEG coating, achieving an average pressure of 1.02 × $10^{-9}$ Pa. In the high-radiation area of the High energy Fragment Separator (HFRS), a self-developed split sealing flange enables remote disassembly and reliable sealing, maintaining 2.5 × $10^{-6}$ Pa. Full integration was completed by September 2024, with all subsystems exceeding design specifications, providing a new engineering paradigm for future large-scale accelerator vacuum systems.

Speaker: wenjun Xie (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Laser phase noise measurements and analysis in High-power Optical Enhancement Cavity

Optical resonators serve as excellent spatiotemporal filters and are widely used for suppressing laser phase noise and stabilizing laser frequency. They can also function as passive optical enhancement cavities, providing power gains of thousands to tens of thousands. High-power optical enhancement cavities hold promise for applications such as steady-state microbunching (SSMB) advanced light sources and gravitational wave detection. However, systematic studies on the phase noise characteristics of high-power optical enhancement cavities remain lacking. In this paper, based on a high-power optical enhancement cavity platform, we measure the phase noise of both the injected laser and the transmitted laser, and investigate the influence of key cavity parameters on the phase noise performance, thereby providing valuable references for the application of high-power optical enhancement cavities.

Speaker: Zhou Yang (Tsinghua University)

TUP7720_edited_version.pdf

16:00 Laser wakefield acceleration in carbon nanotube bundles

Laser wakefield acceleration (LWFA) can produce accelerating fields of several hundred GV/m, greatly reducing accelerator size and cost. Carbon nanotube (CNT) bundles, featuring high plasma density (>10$^{19}$ cm$^{-3}$), tunable effective density, excellent thermal properties, and empty channels that enable laser propagation, have attracted interest as solid-state plasma sources. Previous studies suggested that CNT-based structures can increase the acceleration field to the TV/m range, making them promising for compact radiation sources and radiotherapy. However, the insufficient beam quality still limits their broader application. In this work, we model a hollow solid-state plasma channel composed of CNT bundles. A 2 PW laser from the ELI-ALPS High-Field Laser facility is injected into the channel, where self-injected electrons at the nC-scale are trapped and accelerated in a TV/m field, as shown by particle-in-cell simulations with WarpX. Comparing with previous LWFA results using solid-state targets, we obtain an electron beam with > 2 nC charge and > 100 MeV mean energy, while achieving an unprecedented energy spread < 5%, by tuning the filling factor, bundle diameter, and gap size. We clarify that the large energy spread in the overdense plasma arises from the laser-plasma instability. In addition, we observe strong scattering within the overdense bundle walls. We further aim to investigate how the scattering affects the laser field and, consequently, the beam quality.

Speaker: Jiaqi Zhang (University of Manchester)

16:00 Laser-plasma accelerator based EUV-FEL plasma source development at ELI-ERIC

Laser-plasma accelerators (LPAs) can generate high-energy, high-quality electron beams, paving the way for a new generation of compact free-electron lasers (FELs).
To achieve this, beam stability and repeatability must improve, relying on advances in high-power lasers and plasma-source development. These are key technologies for the 100 Hz LPA-based FEL, under development at ELI ERIC for EuPRAXIA.

In this report, we analyse two plasma-target concepts designed to generate stable, high-quality electron beams essential for compact Extreme Ultraviolet (EUV) FEL applications.
The initial technique creates plasma channels through electrical discharge within a capillary. These channels enhance LPA stability by guiding the laser pulse, and maintaining the laser's focus, thereby improving energy transfer. The characteristics of the channel are influenced by the capillary's shape, gas conditions, and discharge setup.
The second approach uses discharge-free capillaries functioning as gas cells. By modifying the capillary geometry, the plasma density profile can be adjusted to facilitate self-truncated ionisation injection and localise the electron injection. Independent gas inlets allow separate optimisation of injection and acceleration regions.
Furthermore, we investigate the laser-plasma interaction and electron beam acceleration for two different plasma targets using Particle-In-Cell modelling and assess whether the resulting electron beam quality is suitable for LPA-based EUV FEL.

Speaker: Alex Whitehead (Extreme Light Infrastructure Beamlines, Czech Technical University in Prague)

TUP3029_edited_version.pdf

16:00 Laser-plasma electron injector for the cSTART storage ring

Laser-plasma accelerators (LPAs) generate ultrashort, high-intensity electron bunches in a compact form factor. At Karlsruhe Institute of Technology (KIT), we are developing an LPA for direct injection into a specifically built storage ring with high momentum acceptance. The cSTART storage ring (compact storage ring for accelerator research and technology) can be tuned to energies between 50 – 90 MeV, and its lattice is designed to accept electron beams with +/- 4% energy spread. Furthermore, the ring lattice can be set up for the storage of ultrashort electron bunches. The LPA electron injector must be readily tunable to match the storage ring parameters. This contribution reports proof-of-concept experiments that demonstrate the generation of high-quality LPA electron beams with parameters that fulfill the cSTART requirements.

Speaker: Alexander Saw (Karlsruhe Institute of Technology)

TUP3046_edited_version.pdf

16:00 LCLS-II Injector Operational Challenges and Developments

The Linac Coherent Light Source II (LCLS-II) has been in user operations since 2023 and has successfully ramped up the beam repetition rate to 93 kHz. The LCLS-II photoinjector has demonstrated the ability to deliver a high-brightness, low-emittance electron beam at high repetition rates, meeting key performance targets. However, several operational challenges have emerged during commissioning and user operation. These include substantial gun dark current, degradation of cathode quantum efficiency (QE) manifesting as QE craters, unexpected electron beam splitting, significant emittance growth through the laser heater chicane, complications during laser heater commissioning, the presence of beam halos, cathode's QE dependence of the e-beam rate. This paper provides an overview of these challenges and highlights recent efforts to address these outstanding issues, and discuss plans for further improvement of the performance.

Speaker: Feng Zhou (SLAC National Accelerator Laboratory)

TUP2353_edited_version.pdf

16:00 Lifetime improvement using vertical dispersion bumps in a storage ring

The beam lifetime is critical for the synchrotron radiation light source storage rings. By increasing the coupling of the storage ring, the beam lifetime can be improved. However, due to the increased coupling, the beam size around the entire ring also increases. A larger beam size degrades the performance of synchrotron radiation from insertion devices in the straight sections. By using skew quadrupoles to excite vertical dispersion bumps in the arc sections, the vertical emittance as well as coupling can be increased. In this way, the coupling can be localized by minimizing it in the straight sections. This improves the beam lifetime while not affecting the synchrotron radiation from the insertion devices. In this paper, simulations of utilizing vertical dispersion bumps to improve beam lifetime for the ZIPS storage ring is presented.

Speaker: Tao He (University of Science and Technology of China)

TUP2677_edited_version.pdf

16:00 Limitations of intrabeam scattering theories for high-density beams

We revisit the applicability of standard intrabeam scattering (IBS) theories to modern high-density, ultra-low-emittance beams in diffraction-limited storage rings. Classical IBS formalisms by Piwinski, Martini and Bjorken–Mtingwa are derived under assumptions of Gaussian phase-space distributions, small-angle diffusion and weak perturbations. For the parameter range of interest these premises fail: non-Gaussian cores and tails develop, longitudinal–transverse correlations become significant, and the IBS–Touschek continuum renders growth-rate predictions highly sensitive to the specific choice of Coulomb-log and tail-cut parameters. We quantify where these limitations are most severe for multi-bend achromat lattices and discuss consequences for reliable emittance and lifetime predictions in future high-brightness rings.

Speaker: Victor Smaluk (National Synchrotron Light Source II)

TUP2302_edited_version.pdf

16:00 Limiting Magnetic Field Measurements for SRF Cavities

Exploration of new recipes and novel materials for superconducting RF cavities is necessary to push to higher quality factors and accelerating gradients. The superheating field is the material property that sets the limit on the maximum accelerating gradient achievable for a superconducting cavity of a given geometry. The Cornell SuperHeating Radiofrequency Pulsed Power Probe (C-SHRP^3) is a sample host cavity designed to measure the superheating field of material samples. We present results on superconducting materials of interest to the SRF community that demonstrate the high-field potential of novel materials.

Speaker: Nicole Verboncoeur (Cornell University (CLASSE))

16:00 Long time operation of superconducting third harmonic cryomodule at SSRF

Aiming to increase the beam lifetime and to enhance single bunch beam current threshold required by fast X-ray imaging beam line in SSRF beamline phase-II project, a passive superconducting third harmonic cryomodule has been developed. It has been put into Operation since 2021. The development history and long time operation performance will be reported in this paper.

Speaker: Hongtao Hou (Shanghai Advanced Research Institute)

16:00 Machine Learning based preventive maintenance and autonomous power control for RF cavities in a free-electron laser

This project develops a machine learning–based system to prevent RF cavity trips in the free-electron laser by autonomously controlling the applied RF power. Sudden vacuum and current fluctuations within the cavities can cause reflections that trip the machine, and continuous manual monitoring throughout the conditioning process isn't feasible. To address this and potentially improve the conditioning efficiency, process-variable data was collected and analyzed to identify patterns in cavity behavior across operating power levels. A hybrid model combining clustering methods, linear regression, and a classifiers was designed to categorize current ranges, estimate baseline behavior, and detect anomalies. The resulting control program evaluates the machine state over short intervals, decreases power during unsafe conditions, increases it during prolonged stability, and can automatically reset the RF system after a trip. This approach enables faster and safer conditioning of the RF cavities, reduces operator workload, and provides a pathway toward fully autonomous preventive maintenance.

Speaker: Mr Ashish Sharma (Indian Institute of Technology Delhi)

TUP2316_edited_version.pdf

16:00 Magnet Measurements of the HALF Magnets

The Hefei Advanced Light Facility (HALF), a fourth-generation light source based on a multi-bend achromat (MBA) lattice, is currently under construction. The storage ring consists of 20 cells and requires over 800 magnets. To assess the magnetic field quality and perform magnet fiducialization, several dedicated measurement systems have been developed. These include rotating-coil, stretched-wire, and Hall-probe systems. The field quality of multipole magnets is characterized using the rotating-coil system, while their magnetic centers are determined through single stretched-wire measurements. This paper presents the design of the measurement benches, outlines the corresponding measurement procedures, and reports measurement results.

Speaker: BaoHou Liu (University of Science and Technology of China)

TUP7651_edited_version.pdf

16:00 MAGNETIC CENTER MEASUREMENT AND FIDUCIALIZATION METHOD FOR HALF

To meet the stringent alignment requirements for accelerator magnets in the Hefei Advanced Light Facility (HALF),
accurate fiducialization of the magnetic center is essential.
This paper presents a high-precision and efficient fiducialization method developed for HALF, based on a single stretched
wire bench integrated with a precision surface plate. The
system enables precise determination of the relative coordinates between the magnetic center and the magnet fiducials.
Experimental results demonstrate that the overall fiducialization accuracy is better than 10 µm, thereby satisfying the
rigorous demands of magnetic center fiducialization for the
HALF project.

Speaker: BaoHou Liu (University of Science and Technology of China)

TUP7717_edited_version.pdf

16:00 Magnetic design of a prototype hybrid in-vacuum undulator and passive force cancellation system for SPS-II

This paper presents the comprehensive magnetic design and simulation-based optimization of a prototype hybrid in-vacuum undulator (IVU), developed as a proof-of-concept for the 4th generation synchrotron light source (SPS-II) at the Synchrotron Light Research Institute (SLRI). Synchrotron radiation spectra simulations were performed using SPECTRA to calculate the expected photon flux for a configuration featuring a 20 mm period length and a 4.2 mm minimum gap at a 3 GeV electron beam energy. The magnetic structure was subsequently modeled in 3D using RADIA, employing NdFeB permanent magnets and FeCo-V poles. To ensure high-quality field distribution and beam stability, four distinct end-termination configurations were evaluated. The optimal configuration was selected based on its superior effectiveness in minimizing field integrals and beam trajectory deviations. A significant engineering challenge involving a peak attraction force of 18.8 kN was addressed through a Pure Permanent Magnet (PPM) force cancellation system. Through systematic parameter tuning and curve-fitting analysis, an optimized 16 mm period for the PPM array was determined. Furthermore, it was found that a 0.5 mm vertical installation offset relative to the main magnets is required to achieve precise force compensation. Simulation results demonstrate that this optimized system reduces the mechanical load by 99%, resulting in a residual force of only -166.1 N.

Speaker: Nonthaphat Sutthimon (Synchrotron Light Research Institute)

TUP7733_edited_version.pdf

16:00 Mass Production and Installation of Undulators for SHINE

The Shanghai High-Repetition-Rate XFEL Facility (SHINE), a hard X-ray free-electron laser currently under construction in Zhangjiang, Shanghai, will start with three undulator lines, FEL-I, FEL-II and FEL-III, covering a photon-energy range from 0.4 to 25 keV. In the initial construction phase, nearly 100 undulators are required, mainly including 42 U26 undulators for FEL-I and 18 U55 plus 14 U55&U75 double-period undulators for FEL-II. Delivering this large number of devices within a tight schedule imposes stringent requirements on design, manufacturing, quality control, and tunnel installation and integration.

To address these challenges, a collaborative scheme has been adopted in which the Shanghai Advanced Research Institute takes the lead in overall technical design, magnetic measurements, acceptance criteria and test-facility development, while several domestic industrial partners are responsible for precision machining, assembly, factory testing and delivery. This paper presents the mass-production and installation progress of SHINE undulators, describing the series engineering design, production organization and quality-assurance strategy for the U26, U55 and U55&U75 devices, and reporting the current statistics of modules that have passed magnetic acceptance and have been installed in the tunnel. The experience gained provides practical references for the implementation of large undulator arrays at future high-repetition-rate XFEL facilities.

Speakers: Jun Wang (Shanghai Advanced Research Institute), jinya chen (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

16:00 Mass Production of 1.3GHz cavities and performance analysis for SHINE project

Mass production of 1.3 GHz high-Q superconducting cavities for the Shanghai High repetition rate XFEL and extreme light facility (SHINE) has now been successfully carried out. Both high temperature nitrogen doping (N-doping) recipe and mild temperature (Mid-T) baking recipe have been adopted to achieve high-Q performance. The production are shared by five companies to provide cavities at different stages. In the paper, experience with high purity niobium materials and 1.3 GHz high-Q cavities for SHINE will be present and main performance including mechanical properties and Q0-Eacc curve will be reported. The lessons we learned during production will be discussed. Cavities performance from vertical test to horizontal test will be reported, too.

Speaker: Hongtao Hou (Shanghai Advanced Research Institute)

16:00 Measured properties of the mixed helium and carbon ion beam at MedAustron

The implementation of a sequential injection scheme for mixing helium and carbon ions from different ion sources at the MedAustron accelerator facility enabled the first successful delivery of a mixed helium and carbon ion beam in a synchrotron therapy facility. Precise knowledge of both the helium and the carbon properties is an essential input for designing treatment monitoring experiments, however, it is not trivial to distinguish the helium and carbon beam properties within the mixed beam.

This contribution discusses the acquired beam properties delivered to the first treatment monitoring research experiments at MedAustron since late 2025. Most notably, the measurements demonstrate that beam compositions with 0-100 % helium content can be achieved. The mixed beam generation at MedAustron is still in an early stage, which is reflected in significant shot-to-shot fluctuations in the beam intensity and composition as well as differences in the transverse beam sizes of the extracted helium and carbon ions.

Speaker: Mr Matthias Kausel (MedAustron)

TUP8004_edited_version.pdf

16:00 Measurements of magnet prototypes for storage ring of Siam Photon Source II

A series of magnet prototypes have been developed for the storage ring of Siam Photon Source II, the second synchrotron light source in Thailand. The prototypes include dipole, combined dipole, quadrupole, sextupole and octupole magnets for half of the Double Triple Bend Achromat (DTBA) lattice. To validate prototype performance, magnetic field characterization was carried out using stretched wire and Hall probe measurement systems. This work reports the measurement results and describes subsequent improvements to both the magnet design and the manufacturing processes.

Speaker: Thongchai Leetha (Synchrotron Light Research Institute)

TUP7654_edited_version.pdf

16:00 Measurements of single-shot attosecond X-ray pulses at high repetition rate

Electron dynamics in molecules occur on sub-femtosecond timescales and drive fundamental processes such as photosynthesis, catalysis, and chemical bond transformations. Attosecond XFELs provide the temporal resolution and pulse power necessary to probe these phenomena. Emerging superconducting accelerator technology further enables high-repetition-rate operation, enhancing statistical sensitivity of data while compressing measurement time. Here, we present the first direct temporal measurements of single-shot attosecond soft X-ray pulses driven by a continuous-wave high-repetition-rate accelerator. Using angle-resolving electron time-of-flight spectrometers, we perform angular streaking measurements with high energy and temporal resolution, allowing complete pulse reconstructions. These measurements showcase the attosecond science capabilities of LCLS-II at high repetition rates and provide the foundation for controlling and shaping x-ray pulses to study ultrafast dynamics in complex systems with precision.

Speaker: Veronica Guo (Stanford University)

16:00 Mechanical design and structural analysis of septum magnet for Thailand new synchrotron light source (SPS-II)

The Synchrotron Light Research Institute of Thailand is developing a new eddy-current septum magnet as part of the pulsed magnet systems for its next-generation synchrotron light source, the Siam Photon Source II (SPS-II). This work focuses on mechanical design and structural analysis of the septum magnet to improve the prediction of anomalies and potential failures over the machine's operational lifetime. Finite element method is used to evaluate both static deformation of the in-air magnet yoke and transient vibration response of the septum blade under pulsed magnetic force, which can induce fatigue damage through cumulative stress cycles. Static analysis indicates that the proposed design satisfies structural integrity and magnetic field uniformity requirements. The impulse vibration fatigue assessment of the septum blade falls within the ultra-high-cycle fatigue (UHCF) regime, with stablished S-N data for copper alloys providing design guidance for extending the magnet's operational life.

Speaker: Kantanat Phochanasombut (Chulalongkorn University)

TUP7715_edited_version.pdf

16:00 Minimizing Slice Energy Spread Photocathode RF Gun for Ultrashort Electron Bunch Generation

Slice energy spread is a key beam-quality parameter that limits the compression of ultrashort electron bunches. To suppress the RF-dominated slice-energy-spread growth in a photocathode RF gun, a 2.3--2.3 cell configuration with a cascaded cavity with a decelerating field is proposed on the basis of the quasi-DC 2.3-cell X-band gun. Simulations show that, without space-charge effects, the slice energy spread can be reduced from 121~eV to 37~eV, and further to 5~eV after field-ratio optimization. The proposed scheme also exhibits good tolerance to variations in the initial beam parameters, although its compensation capability at high bunch charge is limited by nonlinear space-charge effects. These results demonstrate that the cavity with a decelerating field provides an effective approach for the development of low-slice-energy-spread RF guns for ultrashort bunch generation.

Speaker: Ms Fengyi Zhang (University of Science and Technology of China)

TUP2698_edited_version.pdf

16:00 Modeling of CSR and its cancellation in DBA/Chicane type compressors

In advanced accelerator-based light sources and colliders, bunch compressors like arc-type (DBA) and linear-type (chicane) are widely used to generate high-quality electron beams with kiloampere (kA)-level peak currents. However, a serious problem in increasing the peak current even higher is the significant degradation of beam quality caused by the Coherent Synchrotron Radiation (CSR) effect. To tackle this, we develop a new analytical model for CSR that can describe beam transport with varying bunch lengths, establish a practical framework for analyzing CSR in both DBA and chicane-type compressors, and design CSR-suppressed DBA compressors (arc-type) as well as non-symmetric C- and S-shaped chicanes (linear-type). General analytical conditions for CSR cancellation are derived for these designs. Simulations show that, with these new compressors, high beam quality can be maintained even when the peak current is increased up to 10 kA. This work provides important guidance for enhancing the performance of existing accelerator facilities, as well as for the development of next-generation accelerator-based light sources and colliders.

Speaker: Fancong Zeng (Chinese Academy of Sciences)

TUP2636_edited_version.pdf

16:00 Modelling of the Thermal Effects of Electron Beams on Kapton® for Dosimetry Applications

The understanding of the interaction of high-intensity particle beams with matter is an important aspect for the development of novel accelerator instrumentation. Recently, methods for delivery of ultra-high dose rate radiation have become an increasingly important area of accelerator technology; for example, in the context of FLASH radiotherapy, dosimetry, and particle detector development. In this paper, theoretical models and numerical simulations have been implemented to determine the thermal response of a thin Kapton® foil subjected to irradiation with high-intensity bunched electron beams. Emphasis is placed on the identification of phenomena with the potential to drive the development of novel beam diagnostics and dosimetry methods.

Speaker: Dr Bennet Krasch (Karlsruhe Institute of Technology)

16:00 Monochromation of pulsed electron beams with terahertz radiation

Controlling the energy profile of an electron beam is important for continuous and time resolved spectroscopic and imaging applications that require narrow energy spreads. The energy spread of an electron beam is fundamentally limited by the source, but energy spread that is correlated in time or space can be corrected using an appropriate time- and space-varying force. We present a method of reducing energy spread in photo-emitted electron beams in which laser-derived terahertz fields are used to shape the radial and temporal phase spaces. We show analytically and in particle tracking simulations the absolute limits of monochromation that this technique can achieve for a given source, and characterize non-ideal effects that occur at higher frequencies. The interaction is facilitated by a mirror which is reflective to terahertz and largely transmissive to the electron beam, requiring current losses of only a few tens of percent. Our method significantly outperforms the current output of prism-based monochromators while achieving comparable monochromation.

Speaker: Cecilia Abbamonte (Cornell University (CLASSE))

16:00 Multi-channel high-power desity power supply for klystron solenoid

A control scheme for a high-density multi-channel regulated current power supply based on a compact high-speed PLC is proposed. This scheme adopts a hybrid analog-digital dual-loop control method. The power modules utilize mature commercial modules with built-in analog voltage control loops, while a single PLC constructs the current feedback loops for multiple power modules.
The scheme has been successfully applied to multi-channel focusing coil power supplies in an accelerator, featuring extremely high power density, simple interlocking and communication interfaces, and high operational reliability.

Speaker: Zhouyu Zhao (University of Science and Technology of China)

TUP7665_edited_version.pdf

16:00 Multi-objective Bayesian optimisation (MOBO) for high-quality photoinjector optimisation

Optimising SRF photoinjectors is a challenging task due to the high-dimensional, nonlinearly coupled parameters and competing objectives such as transverse emittance and bunch length. Conventional methods such as manual tuning or MOGA require thousands of evaluations and are impractical for routine operation or computationally expensive simulations. This work presents a multi-objective Bayesian optimisation (MOBO) approach that uses Gaussian-process surrogate models and tunable, uncertainty-aware acquisition functions to identify Pareto-optimal solutions in an order of magnitude fewer evaluations. When applied to the 1.4-cell SRF photoinjector at SEALab, and the 1.6-cell SRF gun and 20m injector beamline for EuXFEL, this optimisation outperforms MOGA in solution-efficiency and provides interpretable sensitivity information for injector tuning. These results demonstrate the potential of MOBO as an efficient, machine-ready strategy for SRF photoinjector optimisation.

Speaker: Emily Jayne Brookes (Helmholtz-Zentrum Berlin für Materialien und Energie)

TUP3069_edited_version.pdf

16:00 Multi-objective bayesian optimization of multi-stage OK-SASE for efficient high-energy XFEL operation

Femtosecond hard X-ray radiation beyond 12.4 keV enables unprecedented opportunities for probing matter at atomic scales, however, its generation remains challenging for self-amplified spontaneous emission (SASE)-based XFELs due to reduced FEL gain, leading to extended undulator requirements and limited radiation efficiency. To address this issue, we investigate a multi-stage optical-klystron SASE (OK-SASE) scheme that enhances microbunching through dispersive sections and shortens the gain length. A multi-objective Bayesian optimization (MOBO) framework is introduced to systematically optimize the configuration. Using SHINE as a representative case, steady-state simulations at 15 keV show that the optimized setup reduces the required undulator length relative to conventional SASE by about 7% to 22%, depending on the electron-beam energy spread. The optimization indicates that several chicanes can remain effectively inactive, enabling a more compact beamline layout. Time-dependent simulations also demonstrate the feasibility of multi-stage OK-SASE for efficient high-energy XFEL operation.

Speaker: Xiaodan Liu (Hunan University)

16:00 NEWGAIN project at GANIL: Construction of the new heavy ion injector for the superconducting LINAC

A new project, NEWGAIN (NEW GAnil Injector), is under construction at GANIL, and aims to build a second injector for heavier beams with A/q up to 7, as an extension of the SPIRAL2 accelerator. With this upgrade, SPIRAL2 will provide high intensity beams, from proton to uranium, thus increasing GANIL international competitiveness both in fundamental science and associated applications.
The paper will provide an update on the progress of the construction phase and the main milestones achieved and to come. The layout and the main technical components of the new injector, based on 2 ECR ion sources (one of them existing), two LEBT, one RFQ and a MEBT section to transport the beam into the present MEBT connected to the LINAC will be presented.

Speaker: Frederic Chautard (Grand Accélérateur Nat. d'Ions Lourds)

TUP3022_edited_version.pdf

16:00 Nonlinear photoemission for bright beams in x-band photoinjectors

In recent years, there has been interest in developing compact x-ray light sources that are significantly smaller and cheaper to build than a conventional XFEL or synchrotron facility. As part of this effort, the compact x-ray light source (CXLS) at Arizona State University is an x-ray source based on Inverse Compton Scattering that produces a high-brightness, short pulse duration x-ray beam. This source operates in blowout mode, meaning a high-charge, short-bunch length electron beam self compresses into a uniform ellipsoid in phase space after emission from the cathode. In this case, producing the electron beam using single photon photoemission with an ultraviolet (UV) laser presents many technical challenges due to a lack of optical materials that can withstand the high intensity UV light for a long period of time. For this reason, we implemented a photoinjector scheme that uses multiphoton emission with a 515 nm femtosecond laser. Using this design, we have been able to achieve a bunch charge of 200 pC and a charge density of 700 pC/mm^2. Furthermore, we have measured a transverse emittance of 0.95 mm mrad and a bunch length of 750 fs downstream. Ongoing work is aimed at integrating a spatial light modulator into the design, which can be used to reduce the electron beam emittance further through adaptive shaping of the laser profile, with the goal of correcting for a spatially inhomogeneous cathode emission and producing a uniform ellipsoid of charge.

Speaker: Sami Tantawi (Arizona State University)

16:00 Nonlinear solution of the Landau-Lifschitz-Gilbert equation

Ferrites may be used to shrink cavity resonator size. If a variable magnetic bias field is applied, the resonance frequency may be varied to follow proton/ion revolution frequency. The RF magnetic field can be applied either parallel or perpendicular to the bias. If the ferrite is near saturation, the incremental permeability is dominated by the electron spins - which are described by the Landau-Lifschitz-Gilbert (LLG) equation. Here (for the first time) the LLG equation is solved analytically in the strong nonlinear regime to give dependence of permeability on RF amplitude. For RF parallel to bias, a spectrum of response frequencies emerges. For RF perpendicular to bias, the resonance frequency rises with amplitude leading to the hardening oscillator "jump" or "snap-back" instability.

Speaker: Dr Shane Koscielniak (TRIUMF)

TUP7304_edited_version.pdf

16:00 Nonlinear transverse beam dynamics in AWAKE Run 2c

The AWAKE experiment harnesses the 400 GeV proton beam from the CERN SPS to drive plasma wakefields, which in turn accelerate a witness bunch of electrons to high energy.  Upgrades are currently being carried out to facilitate the experimental programme of Run 2c, which includes control of the witness bunch quality during acceleration.  We here present the first full simulations of the beam–plasma interaction for AWAKE Run 2c, including self-modulation of the proton drive beam and the acceleration of the witness bunch in the wakefields of the resulting train of driver microbunches.  We demonstrate that the length of the proton drive beam has a significant impact on the transverse wakefield dynamics which impact the quality of the accelerated electron witness.  These simulations inform the choice of parameters for the experiment.

Speaker: John Farmer (Max Planck Institute for Physics)

TUP3035_edited_version.pdf

16:00 NSLS-II operation status and future plans

NSLS-II, a 3 GeV third-generation synchrotron light source at Brookhaven National Laboratory, was commissioned in 2014 with the ultimate performance goal of achieving 500 mA beam current and a vertical emittance at the 8 pm diffraction limit. Since commissioning, the facility has made steady progress, reaching routine 500 mA operation in 2025. Along this path, several challenges were encountered, including the insertion-devices induced coupling variations that depend on the ID gap. To achieve stable operation at the 8 pm vertical emittance, an improvement project is underway to install 15 new skew quadrupoles for precise coupling correction. This paper presents an overview of NSLS-II operational achievements, discusses key challenges encountered, and outlines ongoing improvement efforts and future plans.

Speaker: Guimei Wang (Brookhaven National Laboratory)

16:00 NSLS-II R&D for Operations and Beam Studies

The NSLS-II Accelerator Division is actively pursuing R&D aimed at enhancing storage ring operational reliability, beam stability, high-current performance, and readiness for future upgrades. Recent achievements include reaching 500 mA operation, applying machine learning techniques for reliability improvement, and deploying a Unified Orbit Feedback (UOFB) system that delivers sub-micron beam stability across all beamlines. Additional progress includes the development of specialized timing modes for time-resolved experiments with high-current bunch studies and the implementation of bunch-by-bunch beam position monitors for model-independent lattice characterization. A prototype Complex Bend (CB) magnet was designed, constructed, and successfully tested at the NSLS-II linac beamline, demonstrating the feasibility of this approach for next-generation storage ring upgrades. Together, these R&D efforts enhance NSLS-II’s beam stability and operational efficiency, establishing a strong foundation for ongoing performance optimization and future upgrade readiness.

Speaker: Guimei Wang (Brookhaven National Laboratory)

16:00 Numerical Simulation and Analytical Study of Highly Efficient Plasma Wakefield Injector Scheme in a Cylindrical Plasma Channel

Plasma-based accelerators can produce high-brightness, high-energy electron bunches and are considered a promising alternative to conventional accelerator technology and a potential upgrade path for existing large-scale facilities.

Collider concepts based on plasma wakefield acceleration have already been proposed, and plasma-based injectors for XFELs are under active development.

Both free-electron lasers and particle colliders require highly efficient acceleration schemes capable of delivering electron bunches with low energy spread.

We performed numerical simulations of wakefield excitation by a strong laser pulse using the OSIRIS code, a 2D3V fully relativistic electromagnetic particle-in-cell framework, in a cylindrical plasma channel used to control laser evolution.

We show that a gradually increasing internal plasma density gradient can be employed to control the phase position of an externally injected electron bunch. Using this approach, we enhance the accelerating field and suppress undesirable self-injection.

By optimizing the bunch parameters, we achieved significant energy gain over short distances and tested a "point-like" bunch configuration, which produced an exceptional effective acceleration gradient. In this case, the relative energy spread was as low as 0.4%, and the injected bunch remained within the focusing field throughout the simulation. This scheme shows strong potential for generating high-quality electron beams at facilities such as PETRA IV

Speaker: Mariia Seniak (Lviv University)

16:00 Off-axis hollow-channel plasma tailoring for generating two-color x-ray free-electron lasers

Plasma-wakefield-based acceleration offers a route to realize compact X-ray free-electron lasers, but its application is currently limited by beam quality. Two-color X-ray FEL pulses provide a powerful tool for probing ultrafast dynamics. Here we propose a scheme for generating such pulses by using an off-axis elliptical hollow-channel plasma to tailor the electron-beam phase space while preserving its quality. In this approach, the plasma wakefield imprints a time-dependent transverse tilt along the bunch, while the elliptical channel geometry effectively suppresses the quadrupole wakefield and minimizes the induced mismatch. This enables fresh-slice lasing control at different wavelengths in two undulator sections. Simulations show the feasibility of generating femtosecond-scale, high-power two-color pulses with tunable temporal separation at the Shanghai Soft X-ray Free Electron Laser facility.

Speaker: Haiyang Li (Shanghai Institute of Applied Physics, Chinese Academy of Sciences)

TUP2657_edited_version.pdf

16:00 Operation of the Kara booster in storage-ring mode for accelerator studies and system development

The Karlsruhe Research Accelerator (KARA) booster synchrotron, normally used to accelerate electrons from 53 MeV to 500 MeV for injection into the KARA storage ring, has recently been successfully operated in a stand-alone storage ring mode. This capability was enabled by the modernization of its magnet power supplies and their integration into an EPICS-based control system. Operating the booster in this mode provides a flexible platform for accelerator physics studies, including the development of energy-ramping procedures, characterization of magnet hysteresis effects, and verification of control strategies under low-energy storage conditions. Initial commissioning demonstrated stable beam storage at several energies up to 500 MeV.

The future compact storage ring cSTART, designed for energies of 50-90 MeV, is currently being constructed at KIT. The new power supplies allow preliminary experiments to be conducted across this energy level in the KARA Booster, enabling studies of beam and machine characterizations under realistic conditions. Additionally, the ability to store beam up to 500 MeV supports tests relevant for the KARA storage ring. This mode establishes the booster as a compact and flexible experimental platform prior to deployment in cSTART and the main KARA storage ring. Future work will focus on beam dynamics and diagnostics in the lower energy region with reduced radiation damping, as well as optimization of ramping cycles for stable injector operation.

Speaker: Anton Malygin (Karlsruhe Institute of Technology)

TUP7009_edited_version.pdf

16:00 Operational aspects of crab cavities at the Elettra 2.0 storage ring light source

We investigate the upgrade of the Elettra 2.0 diffraction-limited storage ring light source with radiofrequency transverse deflecting cavities generating picosecond-long X-ray pulses of moderate intensity and high repetition rate. Based on a preliminary RF design, operational aspects, challenges and solutions to make the crab cavity scheme simultaneous to the standard operation of the facility, are presented and discussed, also in view of the users’ community wish list.

Speaker: Simone Di Mitri (Elettra-Sincrotrone Trieste S.C.p.A., University of Trieste)

TUP2002_edited_version.pdf

16:00 Operational Status and Fault Analysis of the CSNS Vacuum System and Development Progress of the CSNS-II Vacuum System

Since the China Spallation Neutron Source (CSNS) was officially commissioned in 2018, its operational performance has been continuously improved. To date, the beam power has reached 185 kW, which is 85% higher than the design value, with a stable annual beam delivery time of more than 5000 hours and good overall operational reliability. The vacuum system serves as the core support for stable beam transport, mainly consisting of the Linear Accelerator (LINAC), Rapid Cycling Synchrotron (RCS), Low?Energy Beam Transfer Line (LRBT), and High?Energy Beam Transfer Line (RTBT). In addition, supporting vacuum systems for application beamlines such as APEP and Back?n have been developed, with operating vacuum pressures ranging from 10⁻³ Pa to 10⁻⁷ Pa.The first?phase vacuum system is equipped with 294 ion pumps, 64 cold cathode gauges, 12 turbo molecular pumps, and more than 600 vacuum pipelines. After nearly ten years of operation, the vacuum system has remained stable overall; however, typical faults such as DTL leakage, bellows corrosion, vacuum gauge fluctuation, and vacuum chain fracture have occurred. Based on practical operational experience, this paper systematically summarizes fault characteristics, analyzes fault mechanisms, and proposes corresponding countermeasures, providing a reference for the stable operation of vacuum systems in similar accelerators.The CSNS?II project was officially launched in 2024 to meet the 500 kW high?power requirement, with a five?year construction plan focusing on superconducting cavities, high?energy proton beamlines, and a muon beamline. The vacuum system has been comprehensively upgraded based on the first?phase configuration. Meanwhile, this paper presents the latest development progress of the CSNS?II vacuum system.

Speaker: Pengcheng Wang (University of Science and Technology of China, Institute of High Energy Physics, Chinese Academy of Sciences)

TUP7675_edited_version.pdf

16:00 Optical emission spectroscopy for beam stability monitoring and plasma characterization at MedAustron

At MedAustron, a synchrotron-based cancer therapy center located in Austria, Optical Emission Spectroscopy (OES) has proven to be an effective technique for monitoring ion source stability, offering a non-invasive alternative to traditional beam diagnostic devices such as Faraday Cups (FCs). Measurements were performed at the MedAustron injector on one of the three identical Electron Cyclotron Resonance Ion Sources (ECRIS), used for non-clinical research. For carbon ion beams, a clear correlation was observed between intensity variations in emission lines of neutral and ionized atoms in the visible range and extracted current instabilities measured on the FC. In this work, we present a study on the correlation between OES and extracted current measurements for proton and helium ion beams as a function of source parameters. Additionally, plasma characterization via OES was carried out to determine plasma parameters such as electron density and temperature via the line ratio method using the YACORA Collisional Radiative (CR) model. The results of this measurement campaign show that the applied methodology is a valid tool for monitoring source stability in parallel with clinical treatment, enabling faster detection of source instabilities and ultimately reducing downtime and speeding up low intensity investigations.

Speaker: Mauro Pivi (EBG MedAustron GmbH)

16:00 Optimization and update of the HALF storage ring physics design

The Hefei Advanced Light Facility (HALF), a soft X-ray diffraction-limited storage ring light source at NSRL, began construction in 2023. This paper presents the optimization and update of the physics design for the HALF storage ring in the past two years.

Speaker: Tianlong He (University of Science and Technology of China)

TUP2627_edited_version.pdf

16:00 Optimization of a storage ring pre-injector for high transmission efficiency and low energy spread

In this paper, the Non-dominated Sorting Genetic Algorithm II (NSGA-II), combined with the beam dynamics code ASTRA, was employed for the multi-objective optimization of the output performance of an electron linear accelerator (linac). Taking the pre-injector of a storage ring light source as an example, the electron linac consists of a thermionic cathode high-voltage electron gun, a sub-harmonic buncher (SHB), a buncher, and a traveling-wave accelerator tube. Maximizing the transmission efficiency and minimizing the rms energy spread were defined as the core objectives of the optimization. The optimization results indicate that the beam energy at the linac exit reaches approximately 65 MeV, with the transmission efficiency exceeding 70 % and the rms energy spread maintained below 0.35 %.

Speaker: Ms Fengyi Zhang (University of Science and Technology of China)

16:00 Optimization of the response matrix measurement application in Pyapas

Measurement of the response matrix serves as the foundation for orbit correction and OPICTS correction. To obtain more accurate response matrix data while minimizing the measurement time, we have meticulously optimized parameters such as the number of data points collected by Beam Position Monitors (BPMs) and the waiting time. Additionally, due to the long overall measurement duration for the entire ring, factors including orbit drift and hysteresis effects during the process can introduce deviations to the measurement results. Therefore, we integrated response matrix measurement with orbit correction and radio frequency (RF) frequency adjustment to further ensure the consistency of the beam state throughout the entire measurement process. This paper will elaborate on the relevant work in detail

Speaker: Haisheng Xu (Institute of High Energy Physics)

TUP2616_edited_version.pdf

16:00 Optimized design of a C-band 100 MeV electron LINAC for FLASH radiotherapy

Electron LINACs are key tools for radiotherapy. Conventional low-energy ones can treat only superficial tumors. Achieving Very High Energy Electrons (VHEE, >100 MeV) enables treatment of deep-seated tumors. Furthermore, electrons are well-suited for delivering Ultra-High Dose Rates (UHDR) required for FLASH therapy, which improves healthy-tissue sparing. Combining VHEE and FLASH in a hospital environment represents an important step forward for Radiotherapy.
In the context of the SAFEST project at Sapienza, this work presents a compact and cost-effective accelerator layout capable of delivering hundreds of nC at 100 MeV within tens of pulses over 1 ms of irradiation. The design emphasizes efficient RF power usage through high-efficiency C-band structures and a pulse compressor. Beam dynamics simulations and low-power RF tests validate the approach. A strong focus is placed on flattening the compressor signal, which must remain stable over 1 mus to accommodate electrons from a triode thermionic gun, a compact and economical source for this accelerator. The resulting 3-m linac, powered by a single 20-MW klystron, shows strong potential for future hospital-based FLASH VHEE treatments.

Speaker: Stefano Farina (Sapienza University of Rome)

TUP3071_edited_version.pdf

16:00 Optimizing a low-gain FEL oscillator for the SAPS Storage Ring: a parameter study

Achieving higher spectral brightness in fourth-generation light sources like the Southern Advanced Photon Source (SAPS) through integrated free-electron laser (FEL) oscillators presents significant challenges. In response, we present a systematic optimization of the parameters for a low-gain FEL oscillator on the SAPS storage ring. Our work quantitatively evaluates how a transverse gradient undulator (TGU) modifies the ring's equilibrium beam parameters and analyzes the effects of harmonic operation and undulator length on FEL gain. These findings offer essential design guidance for implementing such FEL oscillators in storage rings.

Speaker: Fancong Zeng (Institute of High Energy Physics, Chinese Academy of Sciences, University of Chinese Academy of Sciences)

TUP2675_edited_version.pdf

16:00 Optimizing the Design and Data Processing of Tunnel Control Network for Particle Accelerator

With the advancement of large-scale scientific projects, engineering control networks face higher demands. This study focuses on particle accelerator tunnel control networks, addressing key challenges in automated design, data fusion, and deformation prediction. Three main contributions are presented:(1) Automated simulation of laser tracker networks using Spatial Analyzer's Measurement Plans, enabling automated station planning and Monte Carlo simulations for design evaluation. (2) Heterogeneous data fusion, integrating laser trackers with precision instruments. For elevation accuracy, differential leveling models are implemented. For planar accuracy, distance-constrained adjustment algorithms are developed. (3) Machine learning-based deformation prediction using long-term observation data. An integrated workflow establishes multiple prediction models including neural networks for 3D coordinate forecasting, supporting maintenance decisions. Demonstrated at Hefei Advanced Light Facility, this research provides transferable solutions for large-scale engineering applications, balancing methodological robustness with practical implementation.

Speaker: Enchen Wu (University of Science and Technology of China)

16:00 Optimizing the NSLS-IIU energy for maximum brightness at operational beam intensity

The most updated complex bend achromat lattice for the high-brightness upgrade of NSLSII provides a record-low electron beam emittance of 23 pm at 3 GeV. However, collective effects of beam dynamics, especially intra-beam scattering, are the main limiting factors of emittance and brightness at operational beam Intensity. Since the emittance and collective effects are strongly dependent on the beam energy, we estimated the lowest possible emittance scaled with energy and intensity, taking into account intrabeam scattering, vacuum chamber impedance, and bunch lengthening by higher-harmonic RF cavities.

Speaker: Victor Smaluk (Brookhaven National Laboratory)

TUP2301_edited_version.pdf

16:00 Overview of the DONES Programme

IFMIF-DONES (International Fusion Materials Irradiation Facility, DEMO-Oriented Neutron Early Source) is a cutting-edge neutron irradiation facility designed for the study and qualification of materials intended for use in fusion reactors. It also contributes to the development of tritium and breeding blanket technologies. As part of the European roadmap to fusion electricity, its primary objective is to create a comprehensive database of material properties under intense neutron irradiation conditions, similar to those encountered in a fusion reactor. The neutron source is generated by an accelerated deuteron beam striking a liquid lithium curtain, producing neutrons with an energy spectrum and flux comparable to those experienced by the first wall of a fusion reactor.
The IFMIF-DONES facility has advanced from preliminary to detailed design, with some components already in production. Construction officially began on 16 March 2023 following the first DONES Steering Committee, ensuring a smooth handover to the Programme Team. This paper outlines the current status of the DONES Programme and design.
The focus will be on the design status of the DONES Facility and its Accelerator Systems, which are designed for delivering the 5 MW D+ beam at 40 MeV with high availability. Additionally, it will provide an update on the status of hardware procurement through the In-Kind Contribution of the engaged parties and include an overview of the facility's experimental capabilities.

Speaker: Ivan Podadera (Consorcio IFMIF-DONES España)

16:00 Performance analysis of a Mach-Zehnder interferometer using synthetic interferograms

In this work, we assess the performance and limitations of Mach-Zehnder interferometry for plasma diagnostics using a fully synthetic, numerically generated dataset. We explore regions of parameter space that are difficult to access experimentally, including fringe behaviour under different plasma density profiles, the dynamic range of measurable phase shifts, and the resolution limits for low-density plasmas. By introducing controlled phase errors and noise, we quantify the robustness of common phase retrieval and phase unwrapping algorithms and identify the conditions under which these methods succeed or fail. Our results provide practical design guidelines for optimising interferometric measurements across a wide range of plasma conditions.

Speaker: Fatimah Alharthi (University of Manchester, Cockcroft Institute, University of Bisha)

TUP3063_edited_version.pdf

16:00 Performance and production status of the high-Q cryomodules for the SHINE project

The SHINE Linac was optimized to accelerate the beam to 8 GeV with 54 high-Q cryomodules (CMs), benefiting from the higher performance of the cavities and CMs. Currently, the mass production of SHINE cavities and CMs is ongoing. Up to now, around 350 high-Q cavities with mid-T baking or N-doping recipes have been fabricated and tested. Most of them have been assembled in CMs. More than 30 CMs have been tested. In this paper, we report the performance of high-Q CMs and lessons learned during the production.

Speaker: Hongtao Hou (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

TUP7636_edited_version.pdf

16:00 Performance comparison between variable bending magnets and Sandwich magnets in the Southern Advanced Photon Source

The Southern Advanced Photon Source (SAPS) is a planned 3.5 GeV ultra-low emittance storage ring based on a modified hybrid 7-bend achromat (H-7BA) lattice, located in Dongguan, China. To achieve an extremely low natural emittance, the lattice incorporates a novel unit cell consisting of a 'Sandwich' bending magnet combined with reverse bends. This design has resulted in a remarkable natural emittance of 26.3 pm·rad. Although variable bending magnets with a trapezoidal bending radius and gradient are also recognized for their effectiveness in emittance reduction, their performance relative to the compact thin-center 'Sandwich' design remains unclear. This paper presents a comprehensive comparison of these two magnet configurations, detailing the nonlinear optimization process and evaluating their respective performance.

Speaker: Jianliang Chen (Chinese Academy of Sciences)

TUP2614_edited_version.pdf

16:00 Phase velocity measurements in hollow cylindrical dielectric waveguides for THz acceleration

The development of a compact electron accelerator is presented as part of the TWAC (Terahertz Wave Accelerating Cavity) EIC pathfinder project. To reduce the footprint, the project proposes to accelerate the electrons with a 100 MV/m THz travelling wave propagating inside a hollow cylindrical dielectric waveguide. In such a case, particle acceleration depends heavily on the dispersion properties of the waveguide. In particular the phase velocity of the THz wave, driven by the dielectric waveguide properties, must match the velocity of the electrons. We will present prototypes of waveguides, and phase velocity measurements of fundamental HE11 and higher order modes obtained from a vector network analyzer (VNA). The experimental curves are compared with CST simulations and with analytical models. Based on these results, waveguides will be selected to carry out the first THz acceleration measurement campaigns with the PHIL photoinjector in early 2026.

Speaker: Randy Ollier (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

16:00 Physics Design of a High-Performance Linac for Plasma Wakefield Acceleration at IHEP

Beam-driven plasma wakefield acceleration (PWFA) holds considerable promise for next-generation electron-positron colliders and high-energy free-electron lasers, owing to its ultrahigh accelerating gradients. In particular, sustained experimental breakthroughs worldwide indicate that the field is now entering a critical phase toward key advances. To address fundamental physics and technical challenges associated with both electron and positron acceleration in PWFA, the Institute of High Energy Physics (IHEP) has established a plasma wakefield acceleration experimental platform based on the Beijing Electron-Positron Collider (BEPCII). The platform comprises two beamlines and a petawatt laser system. Beamline I deliver electron and positron beams from BEPCII to the experimental area, while Beamline II is a newly constructed 150 MeV high-performance linear accelerator. Together, these beamlines support a range of plasma acceleration experiments, including positron acceleration, electron-cascade acceleration, high transformer-ratio electron acceleration, and external-injection electron acceleration. Notably, Beamline II is capable of generating electron beams with a bunch charge exceeding 5 nC and a peak current above 10 kA. This paper presents a detailed overview of the physics design and current progress of Beamline II.

Speaker: Jingyi Li (Institute of High Energy Physics)

16:00 PIC simulation and characterization of a single-charge ECR ion source: the ALISES 3 source

We present here simulations of ALISES 3, a single-charged Electron Cyclotron Resonance (ECR) ion source developed at CEA, and comparisons with experiments. This source can produce high-intensity proton beams. Using commercial simulation tools, we simulate the key physical parameters such as the RF, magnetic, and electrostatic fields, as well as particle dynamics. These simulations describe particle behavior and interactions (collisions, RF heating, ionization processes…). We aim at proposing a comprehensive numerical model of a single-charge ECR source. These developments will enable the optimization of key ECR ion source parameters, including beam intensity, source lifetime, and emittances. Experiments with the actual source are presented at the end.

16:00 Plasma-wakefield acceleration platform based on shanghai soft x-ray free electron laser

Shanghai soft x-ray free electron laser (SXFEL) facility is China's first x-ray free electron laser facility, which opened to users in 2023. It consists of one 1.5GeV linac, two undulator lines, two beamlines and 6 end-stations. We built a plasma wakefield acceleration (PWFA) platform between the linac and the in-vacuum undulator line, including a 200TW laser system, a pair of IR grating for laser compression and a main chamber for laser-plasma-beam interaction. PWFA based XFEL experiment had been carried out and the saturation of the FEL has been observed. Novel PWFA based FEL schemes are planed to perform in the future, such as multi-color FEL and ultrafast scheme.

Speaker: Zhen Wang (Shanghai Advanced Research Institute)

16:00 Precise Frequency tuning of S-band Pulse compressors in High-power operation in the electron and positron injector Linac of KEK

The KEK electron and positron injector linac uses pulse compressors that amplify the high-power RF waves generated from S-band 40 MW klystrons. It is necessary to precisely tune the compressors operating in high-power operation so that their VSWR is minimal and their output power is maximized. We have developed a real-time and labor-saving tuning system for the compressors. The system comprises of a waveform analyzer and a removable and remote-controlled tuner driver. The analyzer calculates in real-time the frequency shift of each compressor comparing its output waveform with the optimal waveform calculated from its input by using the fourth-order Runge-Kutta method. The frequency shift is eliminated by the tuner while monitored pule-to-pulse by the analyzer. In results, all the compressors were tuned easily and precisely.

Speaker: Hiroyasu Ego (KEK Accelerator Laboratory)

TUP7628_edited_version.pdf

16:00 Preliminary Design of HALF High-Temperature Superconducting Bending Magnet Cryostat

This paper focuses on a preliminary design study of the cryostat for the insertion device magnet—specifically, a high-temperature superconducting bending magnet—in the HALF (Hefei Advanced Light Facility) national major science and technology infrastructure project. Based on three-dimensional modeling and finite element analysis, the structural and thermal performance of the cryostat was simulated and evaluated. Key optimizations were made to the mechanical configuration, thermal conduction characteristics, and spatial layout of the support structures at the temperature ports. A low thermal conductivity tension rod support structure was designed for the cold shield and superconducting magnet assembly, along with a rationally planned layout for the current leads and thermal management pathways. Through systematic heat leak analysis of the dual-temperature zones, a balance was achieved between structural deformation control and heat leak suppression. A preliminary design scheme that meets both structural stiffness requirements and low thermal load criteria is proposed, providing a reference for the subsequent development of an engineering prototype of the cryostat.

Speaker: Jincheng Xia (University of Science and Technology of China)

TUP7671_edited_version.pdf

16:00 Preliminary design of motor drivers for the shenzhen superconducting soft X-ray Free Electron

This report presents the preliminary design of two motor drivers developed for the S3FEL project: one for cavity tuning and the other for coupler adjustment. Both drivers control stepper motors to regulate the resonant frequency and coupling degree of the 1.3 GHz superconducting cavity, respectively. Each driver comprises two functional modules: a motor driver board and a limit signal conditioning circuit. The driver board translates low-power control signals (enable, direction, speed) into high-power outputs to drive the motor. Key design features include optocoupler-based isolation between control and power stages to prevent interference, subdivided stepping for improved positioning accuracy and motion smoothness, and real-time current monitoring to ensure correct output. The limit signal conditioning circuit provides excitation to the limit switches, samples their status, and returns the signals to the controller. Both drivers also supply a holding current to maintain motor position when stationary. Experimental validation confirms that the designed drivers satisfy the operational requirements for precise tuning and coupling control in the S3FEL system.

Speaker: Zhiyuan Zhang (Institute of Advanced Light Source Facilities, Shenzhen)

TUP7633_edited_version.pdf

16:00 Preliminary lattice design to the 1 pico-meter level emittance for the Southern Advanced Photon Source

The pursuit of diffraction-limited storage rings has driven emittance targets into the picometer regime. This paper presents a novel Single Hybrid Multi-Bend Achromat (SH-MBA) lattice design for the Southern Advanced Photon Source (SAPS), targeting an emittance at the 1 pm level. The compact SH‑16BA design, operating at 3.5 GeV with 36 periods and a 945 m circumference, employs high‑gradient quadrupoles, reverse bends, and longitudinal gradient bends. While collective effects such as Intra‑Beam Scattering allow the equilibrium emittance to reach the diffraction limit for hard X‑rays, the most critical challenge lies in nonlinear dynamics optimization. The required sextupole strengths are extremely high, generating nonlinear driving terms three orders of magnitude larger than in typical 4th‑generation sources and restricting the dynamic aperture to about 1 mm. This work demonstrates that achieving a reliable 1 pm-level design will require novel methods to suppress these severe nonlinearities.

Speaker: Jianliang Chen (Chinese Academy of Sciences)

TUP2612_edited_version.pdf

16:00 preliminary physics design of 1.3 GHz superconducting electron gun

Conventional electron guns face limitations in achieving the required accelerating gradients while maintaining satisfactory beam quality for our application. To overcome this challenge, we have developed a superconducting radiofrequency (SRF) electron gun. This gun is specifically designed and operated at a high cathode gradient of 30 MV/m. We present a comprehensive evaluation of its key performance characteristics. This includes detailed analyses of its RF properties and critical mechanical behavior under operational conditions. Specifically, we report on the helium pressure sensitivity, Lorentz force detuning, tuning sensitivity, and modal analysis. These results demonstrate the feasibility of the SRF gun design and provide essential insights into its operational stability and performance at the demanding target gradient of 30 MV/m, paving the way for high-brightness beam applications.

Speaker: XiongHao Yuan (Shanghai Institute of Applied Physics, Chinese Academy of Sciences)

16:00 Preliminary study on the vacuum performance of NEG coated vacuum chambers after venting-activation cycles and storage

The Hefei Advanced Light Facility (HALF) is a fourth-generation synchrotron radiation light source based on diffraction-limited storage ring. NEG coated vacuum chambers provide an effective route for the acquisition of ultra-high vacuum in DLSRs. The vacuum performances of the NEG coated vacuum chamber greatly affect the long-term stability and reliability of vacuum systems. In this work, ternary Ti-Zr-V films were deposited on the interior surface of the small aperture copper vacuum chamber by DC magnetron sputtering. The vacuum performance of the NEG coated vacuum chambers subjected to nitrogen venting-activation cycles and neon venting-activation cycles are investigated, respectively. The pumping capacities of the NEG coated vacuum chambers were evaluated after storage in vacuum, nitrogen and neon atmospheres. Furthermore, the ultimate pressure of the NEG coated vacuum chamber activated by polyimide heaters was tested. This work provides data support for the application of NEG-coated vacuum chamber in the Hefei Advanced Light Facility.

Speaker: Xiaopeng Xu (University of Science and Technology of China)

16:00 Preparation and research of CsBr-Coated Cs3Sb photocathodes

Abstract
Cs$_3$Sb photocathodes are promising electron sources for accelerators because of their high quantum efficiency (QE) under visible light, but the low robustness under low vacuum limits practical operation. In this work, Cs$_3$Sb photocathodes coated with CsBr were prepared and characterized. The experimental results indicate that the coating improved the pressure adaptability of the photocathodes by approximately two orders of magnitude, although it inevitably reduced the initial QE. After exposure, the QE of the coated photocathode can be recovered by annealing to its original value.

Speaker: YUXIN CHENG (Shanghai Institute of Applied Physics)

16:00 Preparatory operational phase for an internal target in the Arronax cyclotron C70XP

The Arronax C70XP cyclotron is used to extract positive ions at fixed energy and protons from 35 to 70 MeV for irradiations. In order to support lower energy irradiations, an internal target system that can be positioned at various radius is being built. Several studies are being performed to investigate the beam behaviour. These studies include intensity profile of the beam as a function of the radius and the impact of several magnet settings. Multiple repetitive checks have also been done and a first operational protocol is being favored to minimise potential impact on the final results for short irradiation in the R&D phase. This phase is part of a more global study that will tackle for example production of Astatine 211 at high intensity. The ongoing work is reported within this paper.

Speaker: Freddy Poirier (Cyclotron ARRONAX)

16:00 Progress from Testing Facility for HPRF SSA System at LANSCE CCL

The high-power radio frequency (HPRF) test facility that was developed at the Los Alamos Neutron Science Center (LANSCE) to evaluate components of a RF Solid-State Amplifier (SSA) system operating at 805 MHz has had significant results towards the targeted final output power of 1.25 MW. The system is powered by a 100 V DC supply and stabilized with a 0.1 F capacitor bank to support transient power demands, capable of storing up to 1.125 kJ of energy. The SSA utilizes Gallium Nitride (GaN) on Silicon
Carbide (SiC) high electron mobility transistors (HEMTs). Multiple HEMT amplifier modules will be power combined to achieve the full 1.25 MW output, with the aim of enhancing reliability, modularity, and maintainability in the current accelerator RF infrastructure. The system employs water cooling to manage thermal loads and ensure stable operation under high duty-factor pulsed conditions. The progress from this test configuration supports ongoing evaluation of solid-state amplifier performance, thermal handling, and integration with RF passive components under realistic operational conditions.

Speaker: Javier Vega (Los Alamos National Laboratory)

TUP7367_edited_version.pdf

16:00 Progress in the PM based LGBM magnets for K-4GSR

A 4th generation storage ring based light source is being developed in Korea since 2021. It features <60 pm rad intrinsic beam emittance, about 800 m circumference, 4 GeV e-beam energy, full energy booster injection, and more than 40 beamlines which includes more than 24 insertion device (ID) beamlines. To optimize the beam emittances, longitudinal gradient bending magnet is applied in the storage ring design. To minimize the operation costs, and to save the lattice space, Sm2Co17 based Longitudinal Gradient Bending Magnet (LGBM) is being developed following ESRF-EBS, and HEPS. It has 5 steps of field level ranging from 0.75 T~0.15 T with approximately 2 m length. In this report, the compensation scheme of temperature dependence, and field tuning to meet the bending angle, and apex points will be described.

Speakers: Seohyeon An (Pohang Accelerator Laboratory), YoungGyu Jung (Pohang Accelerator Laboratory)

TUP7653_edited_version.pdf

16:00 Progress of physics studies and beam commissioning of the High Energy Photon Source

The High Energy Photon Source (HEPS) is a 35-pm, 1360-m storage ring light source being built in the suburb of Beijing, China. The HEPS construction started in 2019, with the main civil construction finished at the end of 2021. In the past two years, the beam commissioning of the HEPS storage ring had been started and bascially finished. In this paper, we will briefly introduce commissioning of the HEPS storage ring, and relavent physics studies.

Speaker: Yi Jiao (Chinese Academy of Sciences)

TUP2602_edited_version.pdf

16:00 Progress of the magnetic measurement bench for pulsed magnets based on a modified vibrating wire technique

A measurement bench, dedicated to the characterization of pulsed magnets such as injection kickers, is under development at ALBA.
The bench employs a modified vibrating wire technique allowing to measure high frequency magnetic fields in the range of hundreds of kHz.
In the traditional vibrating wire technique an AC current carrying wire is stretched through the bore of the magnet and the force acting on the wire is proportional to the product of the wire current and the magnet field.
A vibration of the wire is observed when the frequency of the wire current happens to be equal to the natural resonant frequency of the wire, typically a few hundreds of Hz.
To characterize the high frequency behavior of the magnet, the measurement is modified by offsetting the frequency of the wire current by an amount equal to the magnet excitation frequency. This condition results in a resonant excitation of the wire vibration independently of the magnet field frequency.
A feedback system based on the continuous excitation of multiple frequencies allows to track the resonant frequency of the wire, drastically increasing the measurement accuracy.

Speaker: Oscar Blanco-García (ALBA Synchrotron (Spain))

TUP7010_edited_version.pdf

16:00 Progress on the normal conducting RF cavities for EIC hadron storage ring

The Normal-Conducting Radiofrequency (NCRF) systems for the Electron-Ion Collider Hadron Storage Ring (EIC HSR) comprise four unique cavity systems. These systems include a 24.6 MHz capture and acceleration system, a combined 49.2 MHz and 98.4 MHz bunch splitting system, and a 197 MHz storage system for collider operations. All systems have successfully passed their final design reviews, and the detailed drawings are currently being completed for procurement. This paper reports on the recent progress achieved across these NCRF cavity systems.

Speaker: Silvia Verdu-Andres (Brookhaven National Laboratory)

TUP7307_edited_version.pdf

16:00 Progress on upgrades to CCL resonance control at LANSCE

The resonance control system for the cavity-coupled linear accelerator (CCL) portion of the Los Alamos Neutron Science Center (LANSCE) has been a consistent source of operational downtime. The present system has been used since installation with only minor upgrades, so a system is being developed to replace it with modern components to reduce maintenance and downtime. The present control algorithm maintains water temperature at a set point based on the average RF power, and other parameters that are direct indications of resonance such as the cavity field phase or its ratio to forward power should be implemented to improve issues inherent to the present control system. These relevant data have been collected for several RF modules and analyzed. Additionally, the control of the valve used to maintain water temperature is antiquated, and a commercially available off-the-shelf stepper motor driver is required as other parts are upgraded. A prototype of a new system is discussed.

Speaker: Wesley Hall (Los Alamos National Laboratory)

TUP7315_edited_version.pdf

16:00 Progress Towards RF Conditioning of Low-Loss Couplers for a Conduction-Cooled Cryomodule

This work presents current progress on the conditioning of two new 25 kW couplers optimized for use in a compact, conduction-cooled SRF cryomodule. A connecting waveguide, previously used for conditioning the 805 MHz SNS couplers, was altered for use at 915 MHz. The necessary modifications were determined via RF modeling, while thermal analysis results identified additional cooling requirements during RF conditioning and provided insight about potential higher-power operation. Initial low-power conditioning will be performed with a 2.5 kW solid-state amplifier, with plans to use an industrial magnetron for RF conditioning at 25 kW in the near future.

Speaker: Neil Stilin (Thomas Jefferson National Accelerator Facility)

TUP7312_edited_version.pdf

16:00 Proton-driven plasma-wakefield acceleration for collider applications

Plasma wakefield acceleration offers high field gradients, typically on the order of 10 to 100x larger than conventional RF cavities.  Currently available proton beams have sufficient energy to maintain these wakefields over significant distances, allowing a witness bunch of leptons to be accelerated to the energy frontier, with the plasma acting to mediate energy transfer from the proton driver to a lepton witness.  The ALiVE project is pursuing the use of a sub-millimetre proton drive beam [1,2], which offers the possibility to significantly increase the beam—beam energy-transfer efficiency compared to the longer beams currently available, opening the path to collider applications. In this work, we present the potential application of ALiVE to boost LEP3 to the $t-\bar{t}$ threshold.

Speaker: John Farmer (Max Planck Institute for Physics)

16:00 Pulsed Magnets Development for Thailand's SPS-II

Thailand’s upcoming 3 GeV light source (SPS-II), based on compact fourth-generation storage ring design, requires precise and reliable operation of pulsed magnet systems for successful beam injection and extraction. The requirements exceed our experience from operations of Thailand’s current synchrotron, and also poses significant technical challenge beyond the currently demonstrated capability of local manufacturing.
We present our latest progress in developing the pulsed magnets and power supplies domestically.

Speaker: Taylor Yan (Synchrotron Light Research Institute)

16:00 Pulsed Power Supply Based on an Optically Triggered Thyristor for the Nonlinear Kicker Magnet of HALF

A pulsed power supply based on a high-voltage op-tically triggered thyristor has been developed for the nonlinear kicker (NLK) magnet of the off-axis injec-tion system at the Hefei Advanced Light Facility (HALF). The NLK requires a short high-current pulse with a waveform close to a half-sinusoidal waveform, fast current rise, and low distortion. An LC resonant topology was adopted and an optically triggered thy-ristor was used as the main switch. A saturable induc-tor was introduced to suppress high-frequency oscilla-tions during the current rise. Experimental results show that the developed system can generate a pulse width below 3.2 μs with a peak current of 5 kA and a current rise rate of about 6.25 kA/μs. The output wave-form is closer to the required half-sinusoidal profile than that obtained with a conventional thyristor-based design, demonstrating the suitability of the proposed power supply for kicker magnet applications in ad-vanced light-source facilities.

Speaker: Weibo Hu (University of Science and Technology of China)

TUP2701_edited_version.pdf

16:00 R&D on efficient ultra-high frequency RFQ structures

RFQ (Radio frequency quadrupole) accelerating structures for RF frequencies lower than 400 MHz have been intensively investigated for decades. To realize modern medical accelerators with more compact layouts, there is an increasing interest to use ultra-high frequencies (UHF: 0.3 - 3 GHz). This study performs R&D towards efficient UHF RFQ structures. The design and simulation results will be presented.

Speaker: Chuan Zhang (GSI Helmholtz Centre for Heavy Ion Research)

TUP7901_edited_version.pdf

16:00 R&D Progresses of a 50-period Bulk High-Temperature Superconducting Undulator at Zhangjiang Laboratory

A 50-period, helium-free high-temperature superconducting undulator (HTSU12) has been under development at Zhangjiang Laboratory (ZJLAB) since 2023 for potential deployment at the Shanghai Soft X-ray Free-Electron Laser facility. This prototype device is conduction-cooled using GM cryocoolers and has recently demonstrated an on-axis peak field of ~1.8 T at a period length of 12 mm and a magnetic gap of 4.5 mm (corresponding to a clear mechanical aperture of 4.3 mm). The primary components of the device include a superconducting solenoid that provides the background magnetization field, a cryostat housing a long high-temperature superconducting insert composed of a staggered array of REBCO bulk superconductors, and a high-precision temperature control system. To evaluate the magnetic field quality of HTSU12, we developed an in-vacuum magnetic field measurement system. In this presentation, we report the design, fabrication, cryogenic testing, magnetic field characterization, and subsequent field correction of HTSU12 at ZJLAB. The experimental results collectively highlight the technical achievements and challenges of high-temperature superconducting undulator for integration into next-generation free-electron laser facilities.

Speaker: Kai ZHANG (Zhangjiang Laboratory)

16:00 Radiation of a charged particle crossing a cylindrical resonator with a multilayer wall

The problem of determining the radiation field of a point charged particle in a cylindrical resonator with a multilayer wall is considered. An idealized case is considered: the resonator consists of a segment of a multilayer cylindrical waveguide of finite length, closed on both sides by infinitely thin ideally conducting surfaces. In this case, the radiation field of the particle can be considered separately in three regions independent of each other: inside the resonator and on both sides of it. The axes of the boundary cylindrical surfaces separating the layers coincide with the axis of the waveguide. The number of layers constituting the wall is arbitrary. They can be filled with both metallic materials (with finite conductivity) and dielectrics (with and without losses).

Speaker: Dr Armen Grigoryan (Center for the Advancement of Natural Discoveries using Light Emission, Yerevan State University)

16:00 Radiation of a charged particle entering a semi-infinite cylindrical waveguide with a multilayer wall.

А semi-infinite waveguide with a multilayer wall, the input aperture of which is covered by an infinitely thin ideally conducting plane is being considered. The regularities of the propagation of wave fronts of transition radiation and wake radiation accompanying the motion of a particle are determined for a single-layer resistive and a two-layer copper-dielectric waveguide. For the same cases, the zones of formation of transition radiation (separation of the latter from the field of the particle charge as a result of the difference in propagation velocities) are determined.

Speaker: Dr Armen Grigoryan (Center for the Advancement of Natural Discoveries using Light Emission)

16:00 Radiation-Induced Structural Evolution in TiO₂–ZrO₂ Nano-Oxide Composites for Accelerator Shielding Applications: A Theoretical and Modeling Assessment

The operation of particle accelerators subjects shielding materials to high thermomechanical and irradiation stresses. This study offers a theoretical and computational investigation of the radiation-tolerant properties of TiO₂–ZrO₂ nano-oxide composites. The combination of defect-sensitive TiO₂ (high efficiency for charge trapping) and phase-stable ZrO₂ (transformation toughening) would enhance the irradiation stability of the material. DFT+U and MD simulations were used to investigate equimolar ZrTiO₄ and ZrO₂-enriched (1:9) compositions. Classical MD calculations and DFT relaxation of resulting displacement cascades enabled the evaluation of defect formation energy, evolution of electronic structure and band gap, and stability under realistic accelerator irradiation conditions (fluences up to 5 MeV electron irradiation). It was found that the ZrO₂-enriched composition exhibits better radiation stability characterized by higher oxygen vacancies formation energies, negligible bandgap narrowing, and lower morphological degradation. The role of TiO₂ is related to defect trapping whereas ZrO₂ contributes to mechanical stability, thus showing the presence of synergism. Results could form the predictive basis for future experiments at the CANDLE synchrotron employing irradiation with high-dose X-rays and 5 MeV electrons, followed by SEM/EDS and photoluminescence analyses.

Speakers: Dr Gevick Davoodi (Armenian National Agrarian University), Laya Anjo (Center for the Advancement of Natural Discoveries using Light Emission), Mrs Milena Yazichyan (Center for the Advancement of Natural Discoveries using Light Emission)

16:00 Real-time Storage Ring Optics Monitoring and Correction Feedback System

Recently, an EPICS IOC server was installed in NSLS-II storage ring which provides real-time optics information during the user service periods. The server calculates the storage ring optics using the turn-by-turn (TBT) BPM data triggered by the disturbance from the injection kickers. The data are verified to be reliable, and the efforts are being invested to implement optics feedback system which will continually restore the storage ring optics to the desired status during the user service. This paper presents how the reliable optics information is obtained from the injection TBT data as well as how the data will be used in the optics correction feedback system.

Speaker: Ihar Lobach (Brookhaven National Laboratory)

16:00 Real-Time X-ray Beamline Surrogate Modeling via a Physics-Informed Log-Manifold Learning Framework

Wave-optical simulation of undulator radiation through X-ray beamlines is computationally prohibitive, limiting real-time optimization. The high-frequency diffraction structures and extreme dynamic range of focal spot distributions pose significant challenges to conventional surrogate models. We propose a log-manifold surrogate modeling framework that represents intensity distributions in logarithmic space, converting highly nonlinear diffraction structures into low-rank learnable manifolds. With physics-informed OOD-aware Residual method, the model attains less than 1% relative error over the full dynamic range, faithfully reconstructs fine diffraction fringes, and generalizes robustly across beamline configurations. Single prediction takes only milliseconds, yielding thousands of speedup over SRW simulation and enabling real-time surrogate-based beamline optimization. This work demonstrates an efficient path toward real-time digital-twin beamline modeling for fourth-generation light sources, enabling online optimization, rapid parameter scans, and virtual diagnostics.

Speaker: Xuanying Song (Tsinghua University)

TUP2715_edited_version.pdf

16:00 Recalculation of brilliance of X-ray sources via Lambert function for SASE FELs

In regime of diffraction-limited electron beams at x-ray wavelengths, the spectral width of fundamental spontaneous undulator radiation is at ~1% level, and down to 0.01% for free-electron lasers (FELs). Consequently, the traditional characterization of brilliance in units of 0.1% bandwidth tends to overestimate the actual brilliance of longitudinally coherent sources. An update version of the brilliance plot in units of 0.01% relative bandwidth is proposed. It is shown that, in order to match experimental and simulated data, the calculation has to take into consideration a non-uniform electron current profile in self-amplified spontaneous emission (SASE), whenever produced at the undulator, and the scaling of the light pulse duration with the harmonic jump in seeded architectures. More accurate and general brilliance expressions are therefore provided. A closed-form is found for the saturation length of SASE FELs, providing an exact value via Lambert function, in place of well-known but semi-quantitative estimations reported in the literature.

Speaker: Simone Di Mitri (Elettra-Sincrotrone Trieste S.C.p.A.)

16:00 Recent dark current measurements on the CLARA S-band RF electron guns

The CLARA accelerator at Daresbury Laboratory has recently commissioned a new electron gun as part of a larger upgrade to the machine. The new gun (‘HRRG’) is a high rep rate (400 Hz) 1.5 cell cavity (3 GHz fundamental frequency) designed to produce low emittance beams up to 5 MeV/c, with cathode fields up to 120 MV/m and RF pulse lengths of up to 3 us. The previous CLARA gun (‘LRRG’) was a similar 2.5 cell device but low rep rate (10 Hz). Dark current emitted from the gun is an important issue for several reasons, so is monitored and managed throughout CLARA commissioning and user operation. We present results from the dark current measurements from the new HRRG gun through its commissioning and early stage operation, and make a comparison to those taken from the previous LRRG gun.

Speaker: Frank Jackson (Science and Technology Facilities Council)

TUP3076_edited_version.pdf

16:00 Recent developments towards the SDLS

We report on the development of an advanced storage ring lattice, the Stanford Diffraction-Limited Light Source (SDLS), tailored for installation in the existing PEP-II tunnel at SLAC. The design is based on the hybrid 6-bend achromat (H6BA) architecture optimized for ultra-low emittance while maintaining robust nonlinear dynamics, essential for diffraction-limited synchrotron radiation production. To accommodate long straight sections required for insertion devices and injection systems, we implement the mmodified transparency conditions that mitigate periodicity-breaking effects and preserve dynamic aperture and momentum acceptance. This latest design advances the SDLS concept by combining a new compact (insertion device-less) cell in half of the arcs and the H6BA in the remaining half of arcs. Nonlinear optimization—via multi-objective algorithms incorporating tune footprint control, frequency map analysis, and chromatic detuning minimization—yields a dynamic aperture sufficient for off-axis injection and a Touschek lifetime exceeding those of contemporary third-generation sources.

Speaker: Donish Khan (SLAC National Accelerator Laboratory)

TUP2304_edited_version.pdf

16:00 Recent progress in intense vortex radiation sources at SXFEL

Vortex radiation carries orbital angular momentum (OAM) and is attractive for applications including chiral characterization, magnetic imaging, and ultrafast light--matter interaction studies. A scheme for vortex radiation generation and diagnostics at the Shanghai Soft X-ray Free-Electron Laser facility (SXFEL) based on wavefront shaping of a 266 nm external seed laser is studied. Three-dimensional simulations with realistic SXFEL parameters show clear annular intensity and helical phase distributions, with peak power reaching the sub-gigawatt level at a representative working point. The proposed diagnostics further enable clear identification and characterization of the generated OAM radiation. The results support the feasibility of controlled vortex radiation generation at SXFEL and its future extension to shorter wavelengths.

Speaker: Yin Kang (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

16:00 Recent progress on the infrared free-electron laser facility of Anhui University

Since May 2022, the researchers at Anhui University, Hefei, China have been constructing an internationally advanced infrared free-electron laser (IR-FEL) facility. The project mainly includes one FEL light source device, six experimental stations, and other supporting systems. The tunable IR-FEL system covers the mid-infrared to far-infrared bands. Its linear accelerators provide an electron beam energy of 12-55 MeV, adopting an oscillator-type FEL scheme to generate ultrashort laser pulses (maximum 100 mJ/pulse) with continuously tunable wavelengths (2.5-200 μm), quasi-monochromaticity, and high peak power. The system includes linear accelerators, oscillators, and an optical transmission system, along with electron beam diagnostics, synchronization control, and laser parameter measurement systems. The six experimental stations focus on high temporal, spatial, and energy resolution to realize the characterization and measurement of light-matter interactions, constructing an internationally advanced materials science research platform for light-matter interaction studies.

Speaker: Minxin Wu (Anhui University)

TUP2632_edited_version.pdf

16:00 Reconfiguration options for reusing a permanent magnet undulator as a low-field wiggler source

The Canadian Light Source (CLS) currently operates a 1.9 T superconducting wiggler (SCW) that has been in service since 2005. As the risk of failure and maintenance requirements for this aging device increase, and funding for a permanent replacement remains pending, an interim solution is needed to ensure continued beamline operation. Reconfiguring a decommissioned permanent magnet undulator offers a cost-effective alternative that could minimize downtime. Several approaches to modifying the magnetic layout to enhance wiggler performance are under consideration, with the goal of reusing existing mechanical supports, permanent magnets, and vacuum chambers. Proposed modifications include reducing the gap and halving the magnetic period to achieve the desired field characteristics.

Speaker: Mr Michael Sigrist (Canadian Light Source (Canada))

TUP7358_edited_version.pdf

16:00 Research status on the ECRIPAC accelerator concept

This study presents the current advancement on our investigation of the Electron Cyclotron Resonance Ion Plasma Accelerator (ECRIPAC), revisiting and greatly expanding this original accelerator concept initially developed in the nineties*. ECRIPAC is an innovative compact plasma device able to generate energetic pulsed ion beams using robust and well mastered electron cyclotron resonance ion source technologies, without requirements for axial RF cavities or powerful laser beams. It relies on the gyromagnetic auto-resonance of plasma electrons in a time growing magnetic field**, followed by the axial acceleration of ions through the plasma space-charge field inside a magnetic field gradient, up to energies close to 100 MeV/A.
The theoretical behaviour of ECRIPAC is summarized. Some preliminary results of kinetic plasma simulations inside a preliminary design of an ECRIPAC machine able to accelerate He2+ ions up to approximately 10 MeV/A are presented. Two sets of simulations are considered, one working with a cylindrical geometry and azimuthal mode decomposition in the open-source code Smilei*** and the other using a 3D geometry in the open-source code WarpX****, providing interesting insights on the plasma behaviour inside the accelerator.

Speaker: Andrea Cernuschi (Laboratoire de Physique Subatomique et de Cosmologie)

TUP3008_edited_version.pdf

16:00 RF Commissioning Results in the SHINE

SHINE is an 8 GeV continuous-wave (CW) free-electron laser (FEL) facility, mainly composed of an injector, a linear accelerator, an undulator segment, and experimental beamlines. Currently, for the accelerator section, the commissioning of the injector and the L1 segment of the linear accelerator has been completed. The RF structures in these two segments include a VHF electron gun, an L-band buncher, a dual-feed superconducting cavity, an injection eight-cavity module, two standard 1.3 GHz cryo-modules, and two 3.9 GHz cryo-modules. The RF specification of these accelerating structures have all met the design requirements. This paper will introduce the final parameters achieved through the commissioning of these accelerating structures and some problems encountered during the commissioning process.

Speaker: Yubin Zhao (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

TUP2666_edited_version.pdf

16:00 RF conditioning and microwave gun simulations for the University of Hawai‘i Linac and FEL

The S-band electron linac and free-electron-laser facility at the University of Hawai‘i at Manoa is being recommissioned after an extended period of inactivity. Following the restoration of vacuum and thermionic cathode systems, recent work focused on the high-power RF chain and on conditioning of the linac and microwave electron gun. We report RF conditioning measurements obtained during progressive power-up sessions at 1-4~Hz, including forward power delivered to the linac and forward and reflected power at the microwave gun. The linac RF response is stable and consistent with legacy calibrations, while the gun exhibits strong multipacting signatures. To guide the next conditioning campaign, we also present the developing RF-Track model of the thermionic TM010 gun, incorporating field maps, space charge, and beam loading.

Speaker: Niels Bidault (University of Hawaiʻi at Mānoa)

TUP2330_edited_version.pdf

16:00 RF design and commissioning of a novel multi-harmonic buncher for the TRIUMF 500 MeV cyclotron

The horizontal injection section of the TRIUMF 500 MeV cyclotron has been replaced after 50 years of operation and the historic buncher configuration which consists of two separated double-gap bunchers for the 1st and 2nd harmonics of the cyclotron RF frequency of 23.06 MHz were successfully replaced with a multi-harmonic buncher operating on three harmonics. The novel multi-harmonic buncher structure has two electrodes and three gaps: one electrode driven with 1st and 3rd harmonics and the second electrode – with the 2nd harmonic. It is a combination of two double-gap structures having one common gap inside the cavity. The device is now installed and operational. The RF design, fabrication and commissioning results are presented and discussed in the article.

Speaker: Vladimir Zvyagintsev (TRIUMF)

TUP7305_edited_version.pdf

16:00 RF Design of a brazing-free high repetition S-band photogun

In this paper, we present the RF design of a brazing-free high repetition S-band photogun, emphasizing the innovative use of brazing-free technology to enhance performance and reliability. The primary objective is to optimize the structural parameters to achieve a repetition frequency of 100Hz while simultaneously reaching a cathode field strength of 100 MV/m. Through simulations, we demonstrate that our optimized photogun design meets the required performance metrics, paving the way for advancements in photonic applications and high-frequency electron sources.

Speaker: Zhicheng Huang (University of Science and Technology of China)

16:00 RF design of a compact X-band two-stage pulse compression system

This paper presents the design of a compact X-band two-stage pulse compression system featuring bowl-shaped open cavities, developed for a newly acquired 6-MW X-band klystron. The system consists of a correction cavity chain, a first-stage and a second-stage storage cavity. By employing bowl-shaped geometries, which have an unloaded quality factor ($Q_0$) higher than those of spherical cavities, the system significantly enhances both power gain and compression efficiency. With an input pulse of 5-µs from the klystron, the first-stage pulse can be flattened, generating a two-stage compressed pulse of 200 ns with exponentially decaying waveforms, thereby achieving a total peak power gain of ≥10.

Speaker: Zexin Cao (University of Science and Technology of China)

TUP7613_edited_version.pdf

16:00 RF design of a waveguide Hom-damping 1.3 GHz superconducting cavity prototype

Superconducting radio-frequency (SRF) cavities represent a key technology for modern particle accelerators. In high-current energy recovery linac (ERL) facilities, suppressing higher-order modes (HOMs) is critical to ensure beam stability and minimize additional cryogenic heat loads. This work introduces a waveguide-based scheme to extract and damp harmful HOMs excited by intense beams. A systematic RF design and optimization procedure for this waveguide damping method is presented. By implementing the damping scheme into a single-cell cavity geometry, consistent HOM suppression is achieved while maintaining good properties for the fundamental accelerating mode. The single-cell waveguide HOM-damping cavity, adopting the TESLA shape with an enlarged beam pipe, is currently under fabrication and will be tested in cryogenic experiments.

Speaker: Xiaowei Wu (Zhangjiang Laboratory)

TUP7638_edited_version.pdf

16:00 RF design of the 1 kHz photoinjector for the RUEDI Electron Diffraction Facility

The RUEDI RF photoinjector will have a 2.4 cell S-band gun producing electrons at 4 MeV. The gun is designed to operate at 1 kHz repetition rate. This will be achieved by a combination of RF over-coupling to reduce the pulse length, and an advanced water cooling system based on that of the CLARA 400 Hz photoinjector. The shorter pulse length is also intended to limit the dark current, along with operation at 70 MV/m, and the flat back plate cathode. The cell lengths are optimised to improve jitter cancellation performance, as well as to limit surface electric fields on the irises. The cavity is dual side-coupled into the middle cell with a racetrack coupling cell to reduce the quadrupole component, and has an RF probe on the final cell.

Speaker: Louise Cowie (ASTeC, STFC Daresbury Laboratory)

TUP3074_edited_version.pdf

16:00 RF design of the 49 and 98 MHz normal-conducting cavities for bunch splitting in the EIC HSR

Two normal-conducting RF cavities at 49 MHz and 98 MHz have been developed for the bunch-splitting system in the Hadron Storage Ring of the Electron-Ion Collider. Both cavities use compact quarter-wave-resonator structures to satisfy RF, mechanical, and tunnel-integration constraints. Key components, including the fundamental power coupler (FPC), fundamental mode damper (FMD), higher-order-mode (HOM) dampers, mechanical tuners, and pickup couplers, were optimized to meet all design performance requirements. HOM impedances and powers satisfy their limits across the full tuning range. Frequency shifts due to mechanical tolerances can be compensated by trim tuning to adjust the cavity gap. Multipacting studies were carried out using SPARK3D. The designs of both cavities fulfill the performance and interface requirements and are ready to proceed to the procurement phase.

Speaker: Silvia Verdu-Andres (Brookhaven National Laboratory)

TUP7310_edited_version.pdf

16:00 RF electron guns with controlled longitudinal dispersion for attosecond UED

We formulate the design of a UED-oriented RF gun as a constrained longitudinal-dynamics problem and obtain a nonuniform 2.33-cell S-band solution with controlled longitudinal dispersion. The representative solution, (0.4, 0.93, 1), operated near 45 MV/m, brings the phases of maximum energy gain and minimum time of flight (TOF) into near coincidence and thereby yields a well-defined gun dispersion. For the GPT tracking reported here, the beam at the gun exit has a kinetic energy of 3 MeV, an rms bunch length of 100 fs, a charge of 0.1 pC, and a normalized emittance of about 10 nm·rad. With a matched Double Bend Achromat (DBA) beamline, the bunch is compressed to 940 as rms with 10 fC charge at the sample. For RF-amplitude, RF-phase, charge, and magnet-field jitters of 0.05%, 0.2 ps, 3%, and 0.01% rms, respectively, the sample-plane arrival-time jitter is 600 as rms; source-only scans give 518 as rms from amplitude jitter and 167 as rms from phase jitter. These results show that the proposed model provides a direct route to RF guns specifically suited for attosecond UED.

Speaker: YUXIN CHENG (Shanghai Institute of Applied Physics, Chinese Academy of Sciences, University of Chinese Academy of Sciences)

TUP2694_edited_version.pdf

16:00 RF kicks in the Super Conducting Linac of LCLS-II

RF kicks are produced by misalignments between an electron beam in the acceleration structure. By analyzing these kicks, produced by the super conducting standing wave accelerator for the Linac Coherent Light Source (LCLS-II), a few unexpected observations were recognized. Initially an out-off-phase (90 deg off the accelerating phase) component was observed, which is similar in size to the expected by theory in-phase component. Then other observations like modeling errors (e.g.: not closed three-corrector bumps) let to a deeper analysis of the currently used model.

Speaker: Michael Ehrlichman (SLAC National Accelerator Laboratory)

TUP2332_edited_version.pdf

16:00 Self-consistent WarpX modeling of space-charge neutralization in WHAM-Relevant neutral beams

This work presents Particle-in-Cell (PIC) simulations using WarpX [1] to study neutral beam injection (NBI) [2] physics in Wisconsin HTS Axisymmetric Mirror (WHAM) [3-5]-class beamlines as part of a DOE INFUSE collaboration between Realta Fusion and Lawrence Berkeley National Laboratory. The goal is to develop a self-consistent model that couples beam extraction, gas neutralization, re-ionization, and space-charge compensation. The neutralization model is verified against an analytic matrix formulation for charge-state evolution, and the accelerator model is benchmarked against a published WHAM-relevant positive-ion NBI configuration. WarpX reproduces the single-aperture extracted current and captures the reference downstream beam divergence. The coupled simulation further shows that primary electrons generated by impact ionization reduce the beam potential by about 80%, identifying the dominant space-charge neutralization mechanism. These results establish a benchmarked positive-ion NBI modeling workflow for future multi-aperture WHAM simulations and advanced negative-ion or photo-neutralized beam concepts.

Speakers: Kai Shih (Realta Fusion), Joey Eickman (Realta Fusion), Antoine Latrille (Realta Fusion)

TUP8301_edited_version.pdf

16:00 Septum magnet based on permanent magnet for HALF

We present a septum magnet based on permanent magnet (PM) for HEFEI ADVANCED LIGHT FACILITY (HALF). Permanent magnet are expected to save more energy and take up less space.

Speaker: Weibo Hu (University of Science and Technology of China)

TUP7725_edited_version.pdf

16:00 Shielding calculations and activation studies for the PSI Positron Production experiment

The Future Circular Electron-Positron Collider (FCC-ee) is a proposed next-generation particle accelerator, planned as the first stage of the larger Future Circular Collider project at CERN. It is an electron-positron collider designed to be a precision instrument for studying fundamental physics.

The PSI Positron Production (P$^{3}$) is the planned proof-of-principle experiment for the FCC-ee positron source. The main goal of this experiment is to test new technology and validate the envisioned positron production scheme. To this end, a prototype of the FCC-ee positron source will be hosted at the SwissFEL facility at the Paul Scherrer Institute in Switzerland.

A dedicated bunker has been built inside the SwissFEL tunnel, and the experimental components are being installed.
Simulations have been performed with the FLUKA.CERN Monte Carlo code to dimension the P$^{3}$ bunker and local shielding elements. Calculations have been repeated for various target models since different target options will be tested.

This contribution briefly describes the ingredients of the P$^{3}$ experiment and details the dedicated bunker and the local shielding. It shows the expected dose rate distribution outside the P$^{3}$ bunker. The foreseen activation is also discussed.

Speaker: Maria Ilaria Besana (Paul Scherrer Institute)

TUP3081_edited_version.pdf

16:00 Simulation of Dielectric Wakefield Acceleration in Planar Structures at SwissFEL

SwissFEL has two 1 m-long planar dielectric wakefield structures used for dechirping electrons in its hard X-ray beamline, Aramis. Simulations show the structures also support wakefields that can be used to accelerate following particle beams. Here we introduce the dielectric wakefield structures and ECHO2D simulations that show the longitudinal wake potential dependence on structure gap and drive beam length. We present simulations showing the thickness and permittivity of the structures’ dielectric coating determine the location of the accelerating wake potential. Finally, we compare the longitudinal wake potentials generated in the dielectric structures with those in SwissFEL’s planar metallic corrugated structures.

Speaker: Evan Ericson (Paul Scherrer Institute)

16:00 Simulation of plasma dechirper and lens for laser wakefield acceleration

The quality of electron beams produced by Laser Wakefield Acceleration (LWFA), is controlled through laser parameters and plasma density distribution during the injection and acceleration phases, and in some cases, a specific device providing beam selection or shaping to achieve the electron beam quality needed the envisaged application.

A major challenge in the generation of LWFA electron sources is reducing energy and transverse momentum spread to enhance spectral brightness, requiring advanced techniques to optimize beam quality.

We design plasma density profiles to control electron injection and acceleration, specifically to improve the electron beam phase space characteristics in a compact way. This works presents our numerical study using Computational Fluid Dynamics (CFD) and Particle-In-Cell (PIC) simulations. These simulation results are in good agreement with experimental results obtained at Helmholtz-Zentrum Dresden-Rossendorf.

Speaker: Lodewyk Steyn (Laboratoire de Physique des Gaz et des Plasmas (LPGP), CNRS, Université Paris-Saclay)

TUP3033_edited_version.pdf

16:00 Simulation study of HEPS booster operation at lower injection energy

This study investigates the feasibility of high-charge, low-energy 300 MeV linac-to-booster injection for the High Energy Photon Source (HEPS) injector. The primary aim is to enable a klystron hot-standby for the HEPS linac, thereby enhancing its operational reliability. Energy ramping simulations for the booster were conducted using elegant. Both Gaussian and non-Gaussian bunches were tracked. Simulations and analysis indicate that, with a suitable initial RF voltage, Transverse Mode-Coupling Instability (TMCI) is the limiting factor for the beam transmission rate in the booster. By optimizing the chromaticity to enhance Landau damping, TMCI can be effectively suppressed, significantly improving beam transmission rate. A further reduction in the injected bunch energy spread leads to additional gains in beam transmission rate. Through this synergistic optimization of multiple parameters, it looks feasible to achieve stable transport of beam with bunch charge exceeding 5 nC in the booster at the lower injection energy mode for the HEPS injector.

16:00 Simulation study of the full waveguide design for HiFEL

Hefei infrared Free Electron Laser (HiFEL) facility aims to provide high-quality lasers with wavelengths covering the mid to far infrared range. However, there is an obvious decrease in the output power at long wavelengths. The mode field mismatch and truncation loss at the waveguide to free space region are the main reasons for low output power. We propose a full waveguide design and simulation results suggest that compared to partial waveguide configurations, the full waveguide structure improves the saturated output power in the long wavelength range.

Speaker: Guanzheng Wu (University of Science and Technology of China)

TUP2637_edited_version.pdf

16:00 Simβ-AD Project: methodology to asses activation of radioactive waste produced by Cyclotron Facilities

The Simβ-AD project has been launched in 2022 to resolve the issue regarding the radiological characterization of radioactive waste generated by cyclotron facilities, including β only emitters such as 63Ni, ⁵⁵Fe and ⁴⁹$V. The main goal of Simβ-AD is to develop a methodology that couples an innovative active neutron detector with Monte Carlo simulations. Neutron fluence computed by the RayXpert ** software will be validated against in-situ measurements performed with AlphaBeast CMOS-based neutron detectors to estimate activation of waste produced.
Numerical simulations benchmarked the following transport codes: FLUKA, MCNP6, PHITS, GATE and RayXpert® V2.0.
Experiments covering a broad spectrum of particles, energies and intensities were conducted in partnership with different facilities using passive detectors and the AlphaBeast neutron detectors. Comparisons between experimental results with numerical calculations from various Monte-Carlo codes will be described.

Speaker: Jean-Michel Horodynski (Centre National de la Recherche Scientifique)

16:00 SIRIUS storage ring emittance measurement

The SIRIUS is a fourth-generation Brazilian synchrotron light source whose high brilliance performance is determined by its low nominal electron beam emittance. The measurement of this parameter is crucial to validate the machine design, perform diagnostics, and guarantee beam quality for users. This work presents a methodology to measure the emittance at SIRIUS, combining spectral and spatial analysis of insertion device radiation. Three independent methods were applied: harmonic ratio, profile projection (peak-to-valley), and full 2D spatial profile minimization. Measurements were conducted simultaneously at the EMA (low beta section) and MANACA (high beta section) beamlines. The beta function, required for the final fitting, was measured with its uncertainty (≈ ±10%) incorporated into the analysis. The strategy aids in decoupling emittance from the ring's optical parameters with a certain level of confidence in the beta values. The results for the emittance are around 250-260 pm.rad, consistent with the design value, and demonstrate the effectiveness of the employed techniques. The study confirms the low emittance of SIRIUS and validates a set of methods for its continuous monitoring, advancing the knowledge on emittance measurement techniques.

Speaker: Gabriel Ascenção (Brazilian Synchrotron Light Laboratory, Universidade Estadual de Campinas (UNICAMP))

TUP2337_edited_version.pdf

16:00 SMART - a SMall pArticle accelerRaTor on chip

The miniaturization of particle accelerators via Dielec
tric Laser Acceleration (DLA) * offers a route to ultra
compact, cost-effective devices poweredbycommerciallaser
systems. This work explores the extension of DLA technol
ogy—historically focused on electrons—to protons, aiming
to enable "on-chip" sources of high energy hadrons. We
present the design and simulation of a novel microstruc
ture optimized for the acceleration of non-relativistic pro
tons. Key challenges addressed include the management
of phase slippage and the requirement for strong transverse
confinement of heavy particles at low 𝛽. This study aims
to demonstrate the potential for stable acceleration and fo
cusing, validating the pDLA(proton-DLA) ** concept as a
viable candidate for future compact accelerator architectures.

Speaker: Dr Alan Marcia (Fondazione Bruno Kessler, University of Trento)

TUP3010_edited_version.pdf

16:00 Solid State Amplifier Source Cooling Flow Configuration at LANSCE

The Los Alamos Neutron Science Center (LANSCE) uses 1.25 MW 805 MHz klystrons to power the coupled cavity linac (CCL) that accelerates H- beam from 100 to 800 MeV. Solid-state amplifiers can replace klystrons while providing the same energy input to the CCL. The solid-state amplifiers will require cooling to ensure the radio frequency (RF) components don’t overheat.
The existing water system used for the klystrons will be used to cool the solid-state amplifiers. There will be four “Colosseums”, that consist of a low-level RF blade, 40 high power RF blades, a 40-way splitter, and a 40-way combiner, that will replace one klystron. We must ensure there is sufficient water flow and pressure available to cool all these components. Interlocks are added to the system to ensure the protection of the RF components.

LA-UR-26-23644

Speaker: Taylor Roybal (Los Alamos National Laboratory)

16:00 Space-based modulating-anode particle accelerator system for controlled wave generation

The aim of this research is to improve the design and physics basis of a modulating-anode electron gun for future space-based electron accelerator missions. Unlike grid-controlled sources, a mod-anode introduces a separate biased electrode between the cathode and main anode, allowing direct control of the accelerating field profile. We investigate how the mod-anode potential shapes the electrostatic landscape, modifies electron emission conditions, and governs beam formation, including current rise time, emittance, and transverse focusing. Using particle tracking and electrostatic simulations, we map how mod-anode geometry, gap spacing, and bias waveform impact phase-space evolution, beam stability, and pulse structure during propagation in free space. Particular attention is given to trade-offs between high modulation depth and the increased voltage required for fast beam switching in the absence of fragile grids. The results define design windows for robust, repeatable, and strongly modulated electron beams suitable for in-orbit beam–plasma experiments, while emphasizing scalability to a range of future space platforms.

Speaker: Mr Christopher Roper (Los Alamos National Laboratory, Georgia Institute of Technology)

16:00 Stability Optimization of Electron Witness-Bunch Properties through Wakefield Plateau Formation

Plasma Accelerators can generate high-energy electron bunches over just a few centimetres of distance, offering the potential to become a promising alternative to conventional particle accelerators.
In our work we performed numerical simulations of wakefield excitation by a strong laser pulse using the OSIRIS code to investigate the mechanisms for controlling the accelerated bunch. We explored how the density profile of a cylindrical plasma channel influences the stability and energy gain of an externally injected electron bunch.
By selecting the parameters and utilizing an increasing plasma density gradient, we achieved the formation of an accelerating wakefield plateau. This plateau is crucial because it significantly reduces the electron bunch's energy spread.
We also examined the trade-off between bunch charge density and stability. We observed that increasing the bunch density caused its instability and lead to its subsequent break-up. However, by reducing the bunch’s longitudinal length at the same time, we were able to suppress this instability and keep stable acceleration for even very dense bunches. This work is important for developing stable plasma injectors for facilities like PETRA IV.

Speaker: Mariia Seniak (Lviv University)

16:00 Statistical properties of attosecond SASE FELs

Free electron lasers can now generate xray pulses with durations in the attosecond regime.
Optimal utilization of the short pulses for attosecond science necessitates precise measurement of the pulse durations which there are promising methods to achieve.
However, these are developing experimental techniques, not yet routine procedure.
Until they mature, there is a wealth of information in the measured pulse energies and xray spectra, which are easily obtained.
We show that while this information is insufficient to draw any conclusions about a single shot, with a large enough dataset, the statistics can determine length of the electron bunches, on average.
FEL theory then predicts the distribution of the xray pulse durations.
To achieve this, we extend the classical theory put in place by Saldin and Bonifacio to include short bunches with arbitrary current profiles, deriving integral expressions for some key statistical observables.
The analytical is approach compared to 1D nonlinear simulations, showing good agreement until saturation sets in.

Speaker: Johan Ribbing (Uppsala University)

TUP2001_edited_version.pdf

16:00 Status of HEPS booster operation

The High Energy Photon Source is the first fourth-generation synchrotron light source in Asia. As a green-field facility, HEPS began construction in 2019 and now the commissioning of the storage ring has been basically finished. The booster synchrotron, serving as the second-stage accelerator, completed its initial beam commission-ing between July and November 2023 and was officially put into operation in July 2024 to support the storage ring commissioning. This paper presents the beam per-formance of the booster since the start of operation, key upgrades and optimizations implemented, major opera-tional challenges encountered, and the ongoing plans for further performance enhancement

Speaker: Haisheng Xu (Institute of High Energy Physics, Chinese Academy of Sciences)

TUP2608_edited_version.pdf

16:00 Status of the CARIE high gradient photocathode test facility at LANL

This presentation will report on the status of assembling and commissioning of the Cathodes And Radio-frequency Interactions in Extremes (CARIE) C-band high gradient photoinjector test facility and the status of high gradient testing of a 1.6 cell C-band RF photoinjector at Los Alamos National Laboratory (LANL). The construction of CARIE began in October of 2022. CARIE will house a high gradient copper RF photoinjector and other high gradient C-band accelerating structures (e.g., multi-cell cryo-cooled accelerating structures). The 50 MW 5.712 GHz Canon klystron powers the facility. The klystron was installed and conditioned in 2024. The output of the klystron is connected to a circulator that was conditioned to operate for up to 12 MW of power. The WR187 waveguide line brings the power from the circulator into a concrete vault that is rated to provide radiation protection for an electron beam powers up to 20 kW. The first RF injector that was fabricated is made of copper and does not have cathode plugs. This injector is installed at the end of the waveguide line and is under commissioning. High gradient commissioning of the photoinjector will validate operation of the CARIE facility. The status of the facility, the designs of the photoinjector and the beamline, and status of the high-power testing of the injector and other C-band components and cavities will be presented.

Speaker: Evgenya Simakov (Los Alamos National Laboratory)

TUP7314_edited_version.pdf

16:00 STATUS OF THE SAFEST PROJECT: THE SAPIENZA LINAC PROTOTYPE FOR VHEE FLASH RADIOTHERAPY

FLASH radiotherapy is emerging as a transformative modality in cancer treatment, capable of achieving tumor control while significantly reducing normal-tissue toxicity, thereby improving the overall therapeutic index. To fully exploit this effect—particularly for deep-seated tumors—Very High-Energy Electrons (VHEE) in the 50–150 MeV range are required.
Within this framework, and as part of the SAFEST project (aiming for a 100 MeV machine), Sapienza University of Rome in collaboration with INFN is developing a compact C-band linear accelerator prototype. The system is designed to deliver 24 MeV (loaded) electron beams capable of providing doses of 2 Gy per pulse over a 10 × 10 cm² field at a repetition rate of 100 Hz.
The optimization of the accelerator has required detailed electromagnetic, vacuum and beam-dynamics studies to ensure beam parameters suitable for FLASH dose delivery.
The final technical design report of the LINAC has been completed, and installation is currently underway at Sapienza University. Two irradiation configurations—pencil beam and wide-beam irradiation—are planned for the first in vivo and in vitro studies scheduled for 2026.
In addition, the use of a tantalum converter to generate gamma rays is being considered to expand the irradiation machine’s capabilities and enable comparisons between gamma-ray and electron effects.
This compact electron source for FLASH therapy represents a key milestone for the SAFEST project.

Speaker: Stefano Farina (Sapienza University of Rome)

TUP3072_edited_version.pdf

16:00 Status update of permanent magnet radiation resiliency studies at CEBAF

The proposed energy upgrade of the Continuous Electron Beam Accelerator Facility (CEBAF) incorporates Fixed-Field Alternating-gradient (FFA) arcs utilizing permanent magnet technology. Given the radiation environment within the CEBAF tunnel enclosure, validating the long-term magnetic stability of these materials is a critical step for the project's technical feasibility. This contribution presents an overview of the ongoing permanent magnet radiation resiliency program at Jefferson Lab. We briefly review the experimental methodology used to monitor demagnetization in situ and summarize the operational experience from the initial data-taking campaign. Furthermore, we discuss the upgrades implemented for the second exposure campaign, currently underway, which aims to refine dose correlation and reduce systematic uncertainties. We report on the general status of the program and the roadmap for certifying permanent magnet optics for the proposed upgrade energies.

Speaker: Stewart Boogert (Cockcroft Institute)

TUP7370_edited_version.pdf

16:00 Strain gauge implementation for a Nb_3 Sn superconducting multipole wiggler developed in KEK Photon Factory.

KEK Photon Factory is developing a Nb_3 Sn superconducting multipole wiggler (SC-MPW) for a next generation light source ring. The test coil unit has three round Nb_3 Sn coils and works as a three-pole wiggler. Nb_3 Sn superconductivity is strain sensitive, and training of resin impregnated Nb_3 Sn magnets could be limited by wire motion or cracks of the resin. Thus, it is important to monitor strain variation during cooling and excitation processes. Following the Unit 1 [1], we conducted an excitation test of the Unit 2 at the current density of 378 A/mm². In this test, one of the purposes is to validate a new strain measurement system that was first introduced into the Unit 2. Multiple strain gauges were attached to the magnet for monitoring strain variation. The strain measurement points were determined by ANSYS-FEM simulation. We also compared the simulation results with the measured values to assess our FEM model. In the future, we plan to conduct excitation tests at the target current density of 1000 A/mm², In the test, the strain-monitoring system will be implemented to the quench detection. We will report on the test results of the Unit 2 and progress of the next excitation test.
[1] C. Mitsuda, et al.: Proc. IPACʼ25, Taipei, Taiwan Aug.(2025) p.1851-1854

Speaker: Shota Nishi (The Graduate University for Advanced Studies, SOKENDAI)

TUP7660_edited_version.pdf

16:00 Strengthening Europe’s Accelerator Ecosystem: The Role of the Accelerator Science and Technology Industry Permanent Forum (AIPF)

The Accelerator Industry Permanent Forum (AIPF) has rapidly evolved into a strategic platform connecting industry and research institutions across Europe. AIPF’s mission is to enhance cooperation within the accelerator ecosystem, fostering industrial engagement in Big Science initiatives.

In two years since its creation, AIPF has been involved in several high-level European policy-shaping activities, contributing to discussions on industrial readiness, supply-chain, and innovation pathways for research infrastructures. AIPF brings together companies of all sizes and leading research laboratories to identify barriers, opportunities, and solutions for more effective collaborations. Activities include the definition of methodological tools and frameworks aimed at improving procurement processes, co-development approaches, and early industrial integration in scientific projects.

In this contribution, we present AIPF’s objectives, governance model, achievements to date, and ongoing workstreams. We highlight how an industry-driven forum can support Europe’s strategic ambitions in accelerator science and technology, especially at a time when strong partnerships between laboratories and industry are crucial.

Speaker: Josef Troxler (Ampegon Power Electronics AG)

16:00 Studies on the impact of the beam time structure on VHEE/FLASH irradiation biological effects

The CERN Linear Electron Accelerator for Research (CLEAR) provides versatile electron beams for multidisciplinary studies, including advanced research on Very High Energy Electrons (VHEE, 100–200 MeV) at Ultra-High Dose Rates (UHDR >10⁸ Gy/s) for radiotherapy in the FLASH regime, in which normal tissue toxicity is reduced when the dose is delivered within milliseconds. Leveraging CLEAR’s adjustable beam time structure, recent experiments explored how short-timescale beam parameters (down to the picosecond level) influence physico-chemical and biological responses. Such studies were carried out in collaboration with radiobiology groups, particularly at the Hôpitaux Universitaires de Genève mainly using zebrafish embryos. Results indicate that beam intensity and bunch structure strongly affect biological outcomes. Notably, zebrafish morphogenesis can be preserved at instantaneous dose rates near 10¹¹ Gy/s, even when total dose delivery extends to minutes, at average dose rates well below what was so far considered the FLASH threshold. These results highlight CLEAR as a unique platform for defining beam conditions relevant to the FLASH effect in view of future clinical systems.

Speakers: Pierre Korysko (University of Oxford), Wilfrid Farabolini (European Organization for Nuclear Research)

16:00 Studies on Virtual Platform for the HALF Beamline

The autonomous alignment and optimization of synchrotron beamlines pose significant challenges. Traditionally, manual alignment is a time-consuming and experience-dependent process, often requiring extensive diagnostic efforts and data collection. With the construction of the Hefei Advanced Light Facility (HALF) underway, the development of a virtual platform for beamlines will be an invaluable tool for beamline scientists and users. This platform will enable software testing and improve the prediction of optical element parameters in advance. In this paper, we present the development and comprehensive study of a virtual platform representing beamline BL10 at HALF. Additionally, we explore the integration of an AI-driven control system for optical element control in next-generation synchrotron radiation beamlines within the virtual platform.

Speakers: Xueting Wu (University of Science and Technology of China), Fang Li (University of Science and Technology of China)

16:00 Study and test of a triode gun for the FLASH electron LINAC at Sapienza

A 24-MeV prototype LINAC is under development at Sapienza University of Rome for FLASH radiobiological studies. The injector is a 12-keV triode thermionic electron gun from HeatWave Labs, providing grid-controlled current modulation for high current, low perveance, and short-pulse operation. To optimize its integration with the 24 MeV C-band hybrid standing and travelling wave structure, extensive particle tracking simulations of electron gun were performed using CST Particle Studio. Parametric scans of the anode voltage and grid potential were used to evaluate beam current, perveance, and emittance, identifying operating points that balance beam stability and charge for FLASH applications.
As the modern dispenser cathode requires stringent vacuum conditions below 1E-6 mbar, the LINAC was also modeled in Molflow+ to predict pressure profiles under realistic gas-load scenarios. Simulations revealed a potential vacuum limitation near the gun, leading to the design and implementation of an additional pumping port for better evacuation of gas molecules.
These results are benchmarked with initial experimental tests performed on an electron gun test bench at Sordina IORT Technologies and with Flash LINAC at the department of Basic and Applied Sciences for Engineering in Sapienza.
The combined simulation and experimental validation provides key requirements of an injector for a compact commercial LINACs for Flash applications.

Speaker: Shoaib Akbar (Sapienza University of Rome)

TUP3073_edited_version.pdf

16:00 Study of a dual-feed TM020-mode Cavity for the Super Tau-Charm Facility

The TM020-mode cavity offers a high quality factor, a large shunt impedance, and effective higher order modes (HOMs) damping, while maintaining a compact longitudinal structure. However, in single-input cavities, the coupling iris experiences excessive thermal loading as the input power increases, and insufficient cooling eventually degrades cavity performance. To address this issue, we developed a two-input cavity design that reduces the power handled by each input coupler while preserving the total input power. This configuration improves field symmetry and suppresses leakage of the operating mode. The optimized two-input cavity operates at 499.7 MHz, achieves a quality factor of 60,000, provides a shunt impedance above 5 MΩ, and maintains a leakage rate below 1%.

Speaker: Chengzhe Wang (University of Science and Technology of China)

TUP7610_edited_version.pdf

16:00 Study of gas scattering–induced beam losses and collimation for the SOLEIL II storage ring

The SOLEIL II storage ring will be equipped with many in-vacuum undulators (IVUs) and superbends, which are vulnerable to gas scattering–induced beam losses due to their small vertical gaps. In this paper, gas scattering–induced beam losses in SOLEIL II are studied with tracking simulations. The results show that, without vertical scrapers, 53$\%$ of elastic scattering–induced losses happen at IVUs with 4 mm vertical gaps, posing a risk of damage to their magnets over 15 years of operation. Detailed tracking finds that most of these losses originate from scattering events in short range, e.g., within half a turn. This suggests that one vertical scraper located upstream of each IVU group could provide optimal collimation, protecting the IVUs while maintaining the beam lifetime. However, this scheme is not allowed due to space constraints. A second optimal vertical collimation scheme is proposed with 2 scrapers, which reduces the beam losses at IVUs by 40$\%$ while maintaining an elastic scattering lifetime of 40 hours. In contrast to elastic scattering, inelastic scattering leads to only minor beam losses and remains acceptable.

Speaker: Yuejing Huang (National Synchrotron Radiation Laboratory)

TUP2617_edited_version.pdf

16:00 Study of Harmonic Radiation from SASE and Self-Seeded FELs in the PAL-XFEL Hard X-ray Undulator Line

Recent experiments at the PAL-XFEL hard X-ray beamline have reported that X-ray microscopy measurements performed with an XFEL beam of 10 keV fundamental photon energy exhibit a significantly improved signal-to-noise ratio when using self-seeded FEL pulses compared to SASE FEL pulses. A possible explanation suggested in those studies is that self-seeded FELs produce substantially lower background signals arising from high-harmonic radiation than SASE FELs. In this presentation, we aim to clarify the underlying reasons for this behavior by investigating the harmonic radiation generated in the PAL-XFEL hard X-ray undulator line. We present GENESIS simulation results of harmonic emission for both SASE and self-seeded FEL configurations over a range of fundamental photon energies. In addition, we report experimental results of the second and third harmonics obtained using a double-crystal monochromator at a fundamental photon energy of 5 keV.

Speaker: Chi Hyun Shim (Pohang Accelerator Laboratory)

16:00 Study of the Emissivity of Copper Oxide Thin Films by Cylindrical Magnetron Sputtering

High-energy electron beams operating in accelerator vacuum chambers can easily cause heat accumulation on the surfaces of in-vacuum components. When convective cooling and effective conductive heat dissipation are limited, the thermal radiation capability of material surfaces becomes an important heat dissipation mechanism. In this study, copper oxide (CuO) thin films were deposited on Oxygen-Free Copper (OFC) substrates to investigate their enhancement of surface thermal radiation char-acteristics. Experimental results show that the prepared CuO films exhibit dense columnar grain structures with a monoclinic CuO (002) preferred orientation. Emissivity measurements indicate that the average high-temperature emissivity of bare OFC substrates is approximately 0.1, while CuO-coated samples can achieve values up to 0.52, demonstrating improved infrared thermal radiation performance. The coating system setup, experimental procedures, and emissivity measurement methods will be fur-ther described in this paper.

Speaker: Yi-Chen Yang (National Synchrotron Radiation Research Center)

TUP7694_edited_version.pdf

16:00 Study on polarization control of planar undulator system based on magnetic field modulation

The fast polarization switching of undulator radiation has attracted more and more attention in recent years. Recently, a new method has been proposed for fast polarization switching up to kilohertz of undulator radiation by using magnetic field modulation generated from low-current electromagnetic coils. Through fast switching the power of coils, the radiation spectra of two undulators can be rapidly shifted into and out of the bandpass of a monochromator, enabling fast polarization switching for the user beamline. In this paper, we have studied the performance of the scheme using planar undulators. The performance of related parameters, such as photon flux, polarization degree, and spot distribution, will be reported.

Speaker: NanRui Yang (University of Science and Technology of China)

TUP2707_edited_version.pdf

16:00 Study on the vacuum properties of Pd/Ti bilayer thin films

Non-evaporable getter (NEG) thin films are essential for achieving ultra-high vacuum in the narrow-bore chambers. Pd/Ti bilayer NEG thin films were deposited on oxygen-free copper and silicon substrates by DC magnetron sputtering. The microstructure and elemental distribution were characterized by scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). The films exhibit a cauliflower-like surface morphology and a columnar cross-sectional structure, providing a high specific surface area and effective pathways for gas diffusion. The pumping speed for H$_2$ was evaluated using the constant-pressure dynamic flow method after activation at 150 °C for 12 h. The pumping speed decreases from 0.13 to 0.02 L s$^{-1}$ within a pumped quantity range of $1 \times 10^{-5}$ - $6.5 \times 10^{-3}$ Pa L. A non-monotonic variation in pumping speed was observed, which is attributed to hydrogen adsorption, dissociation on the Pd surface, and subsequent diffusion into the Ti layer for hydride formation. The results demonstrate that the Pd overlayer effectively enables low-temperature activation and enhances hydrogen sorption behavior, indicating that Pd/Ti NEG thin films are promising candidates for ultra-high vacuum applications in accelerator systems.

Speaker: Tao Guo (University of Science and Technology of China)

TUP7683_edited_version.pdf

16:00 Sub-10 fs synchronization in laser-plasma accelerators with terahertz frequency bunch manipulation

There is a growing demand for generating and transporting very short femtosecond-scale, high-charge-density relativistic electron bunches [1-2]*. Applications range from extreme light sources such as free-electron lasers to future linear colliders. Laser-plasma wakefield accelerators (LWFA) [3] offer a promising approach for compact high-gradient acceleration, but electrons generated directly from the plasma in a non-linear self-injection process show poor stability and limited control. External injection [4-5] provides a solution but requires extremely short electron bunches with precise control, which is currently limited by compression and timing jitter in conventional radio-frequency accelerators [6].
We show that laser-driven terahertz (THz) control of electron bunches can enable phase-locked, laser-synchronized compression with suppressed time jitter [7]. Using computational methods, we explore the external injection of such THz-controlled electron bunches into a LWFA. By utilizing intrinsic synchronization and THz-driven energy manipulation, we demonstrate significant stabilization in external injection while preserving high bunch quality.

Speaker: Mr Aras Amini (University of Manchester, Cockcroft Institute)

TUP3021_edited_version.pdf

16:00 Suppression of longitudinal instability at NanoTerasu

NanoTerasu is a newly constructed 3 GeV light source located in Sendai, Japan. The circumference of storage ring (SR) is 349 m and the natural emittance is 1.1 nm rad which is realized by the double-double-bend achromat lattice. The compact normal-conducting RF cavity operating in the TM020 mode with higher-order mode (HOM) dampers is employed for beam acceleration. The commissioning of the SR started in June 2023. However, the longitudinal instability was observed during the SR commissioning in 2023 at a beam current of approximately 150 mA. Although partial suppression was achieved by adjusting the RF cavity temperature, the stored beam current during user operation in 2024 remained limited to 200 mA. To overcome this limitation, a compact waveguide-overloaded kicker cavity and longitudinal bunch-by-bunch feedback (LBBF) system were developed and installed. The commissioning of the LBBF system in July 2025 enabled stable beam storage at the design current of 400 mA. The stored beam current for user operation was subsequently increased, and routine user operation at 400 mA with high reliability began in November 2025. The suppression of longitudinal instability will be presented.

Speaker: Kota Ueshima (National Institutes for Quantum Science and Technology)

TUP2681_edited_version.pdf

16:00 Sustain thermal insulation vacuum of a liquid nitrogen cooling system for TPS cryogenic permanent undulator

At the Taiwan Photon Source (TPS) a cryogenic permanent magnet undulator, CUT18, utilizes the latent heat of vaporization of liquid nitrogen for magnet cooling. After a period of operation, some condensed water, which caused rust at the structure of CUT18, appeared at the flange connecting the cooling system and the vacuum beam chamber of CUT 18. This condensed water was mainly due to deterioration of the thermal insulation vacuum of the liquid nitrogen cooling system. Moreover, the period became much shorter after the maintenance to recover a proper vacuum under cold conditions. This paper presents the efforts to extend the period of sustaining a proper thermal insulation vacuum without the appearance of condensed water. A residual gas analyzer was used to study outgases from the insulation vacuum of the liquid nitrogen cooling system at warm and cold conditions. These efforts succeed to extend the period longer than three months, thus greatly reduced the burden from insulation vacuum maintenance.

Speaker: Ping-Shun Chuang (National Synchrotron Radiation Research Center)

TUP7673_edited_version.pdf

16:00 Sustainability-oriented cryogenic permanent magnet undulator (LN₂-enabled C³-CPMU)

A sustainability-oriented cryogenic permanent magnet undulator, the LN₂-enabled C³-CPMU, has been success-fully demonstrated at the Taiwan Photon Source (TPS). The system is designed to address cryogenic performance, thermal stability, and cost efficiency for high-current storage ring operation (up to 500 mA). The undulator employs a conduction-cooled architecture combined with an LN₂ reservoir-based cooling scheme with simplified flow and pressure control, eliminating the need for dedi-cated cryogenic units. Operating at an intermediate tem-perature of 150–160 K, the system consumes approxi-mately 8 L/h of LN₂. Active temperature control main-tains the magnet temperature within ± 0.08 K under vary-ing beam conditions, ensuring stable magnetic field per-formance. The enhanced magnetic properties at cryogenic temperatures enable shorter undulator periods, while integration with existing facility LN₂ infrastructure sig-nificantly reduces system complexity and operational overhead. These results demonstrate a scalable and ener-gy-efficient solution for next-generation synchrotron and XFEL light sources.

Speaker: Jui-Che Huang (National Synchrotron Radiation Research Center)

TUP7705_edited_version.pdf

16:00 SymCSR: Tracking 6D phase space dynamics of electron beam with coherent synchrotron radiation

Coherent synchrotron radiation (CSR) is a critical effect in the design and operation of high-brightness electron accelerators, as it can lead to significant energy loss and emittance growth. In this paper, we present SymCSR, a first-principle tracking program for simulating the 6D phase space dynamics of electron beams under the influence of CSR. SymCSR computes the radiation reaction field of electrons based on its retarded and instantaneous trajectory, which efficiently reduces the requirement on macroparticle numbers. The dynamics of electron beam in various dimensions are calculated using SymCSR and are compared with theoretical models.

Speaker: Zhuoyuan Liu (Tsinghua University)

TUP2641_edited_version.pdf

16:00 Symplectic Tracking of Damping Wigglers Using Generalized Gradient Representations

Strong wigglers are installed in the storage ring to provide a strong damping effect and thus can make the particle beam reach an equilibrium state quickly. Nevertheless, particle tracking of damping wigglers with strong peak field strengths typically uses the field map analysis approach, which does not account for radiation effects and quantum excitations in ELEGANT. To address this, the Generalized Gradient Expansion (GGExp) method is employed to describe the strong magnetic fields of damping wigglers in storage rings. The GGExp method provides an alternative approach to define the wiggler field, incorporating synchrotron radiation effects with symplectic tracking, and offers benefits for both linear and nonlinear analysis.

Speaker: Dr Weijie Fan (Shanghai Advanced Research Institute, Chinese Academy of Sciences)

TUP2679_edited_version.pdf

16:00 Test cavity and Iris-to-Coax transition for tuning and high-power verification of SNS DTL iris couplers

The Spallation Neutron Source (SNS) Drift Tube Linac (DTL) employs iris couplers to efficiently deliver RF power into the accelerating structure. To support the development, tuning, and high-power conditioning of these couplers prior to installation in the actual DTLs, a dedicated test cavity and an iris-to-coaxial transition structure have been designed. This work presents the electromagnetic design, simulation, and optimization of the test setup, enabling precise characterization of the iris coupler’s performance. The transition structure allows for tuning of the iris opening dimensions without requiring a waveguide taper or full-size waveguide transitions, while maintaining impedance matching between the coaxial feed and the iris geometry to minimize reflection and power loss. During low-power tests, the iris opening dimensions can be evaluated using the iris-to-coaxial transition attached to the test cavity. For high-power conditioning, full-size waveguides with ceramic vacuum windows are connected to the test cavity to replicate operational conditions. Key design parameters were optimized using CST Studio Suite, and sensitivity studies were conducted to assess the impact of mechanical tolerances on RF performance. The resulting test platform provides a reliable and efficient means for tuning and validating iris couplers, contributing to improved operational stability and RF efficiency in the SNS DTL.

Speaker: Sung-Woo Lee (Oak Ridge National Laboratory)

TUP7321_edited_version.pdf

16:00 TEST OF C-BAND ELECTRON LINAC FOR FLASH RADIOTHERAPY

Delivered at Ultra-High Dose Rates (UHDR), in the so-called FLASH regime, electron irradiation has shown the remarkable ability to spare healthy tissues while preserving tumor control, opening new perspectives for next-generation cancer treatments. The advancement of high-gradient accelerating structures has enabled the development of compact and cost-effective linear accelerators suitable for clinical environments.
Within this framework, we present the electromagnetic design and testing
results of the C-band RF prototypes for a 24 MeV Linac being installed at Sapienza University. The linac is composed of a standing-wave and a
traveling-wave section. The standing-wave structure has been designed,
manufactured, and tuned in collaboration with SIT Company, while the
traveling-wave structure has been entirely developed in-house, including full fabrication and tuning, in collaboration with INFN. These prototypes represent a key step toward the realization of an advanced FLASH VHEE source for future clinical applications.

Speaker: Stefano Farina (Sapienza University of Rome)

TUP8037_edited_version.pdf

16:00 The CERN Accelerator School - a shining beacon in the training landscape of accelerator science and technology

The field of accelerator science and technology is crucial for advancements in fundamental physics, medical applications, and industrial processes, and via its technological inventions has a considerable impact on society.
The specialized nature of the accelerator domain necessitates highly skilled personnel. However, the domain of accelerator science and technology is rarely taught as it requires a high specialisation in the different domains.
To provide training opportunities is an excellent possibility to demonstrate the diversity of the field and to attract and keep young talent in the domain of accelerator technology.
The CERN Accelerator School (CAS) has played a pivotal role in addressing this need for over four decades, providing comprehensive training to a global community of scientists and engineers.
This talk will explore the crucial role CAS plays within the broader global training landscape for accelerator science and technology, and its contribution to the advancement of this striving field.
This presentation will specifically cover: an overview of the school's evolution and structure; the expansion and adaptation of CAS courses to reflect advancements in accelerator technology and emerging research areas; the impact on the accelerator community; global collaborations; complementary programs; and addressing future needs.

Speaker: Frank Tecker (European Organization for Nuclear Research)

TUP8034_edited_version.pdf

16:00 The collimator system for reducing the dark current in NSRRC photoinjector

The NSRRC photoinjector generates ultrashort electron beams for the production of superradiant radiation in the 100–500 μm wavelength range using a gap tunable U100 planar undulator. The accelerator consists of an S band, laser driven photocathode RF gun equipped with a compensation solenoid, followed by a 5 m long linear accelerator. Sub picosecond electron bunches are achieved through velocity bunching in the linac. Under specific operating conditions, electrons emitted from the cathode surface may be accelerated to high energies independently of the main beam, which continues to gain energy in the linac. These stray electrons can impact the vacuum chamber, producing unwanted radiation that poses risks to both accelerator components and radiation safety. To suppress dark current, a collimator was installed between the photocathode gun and the linac to intercept these electrons prior to downstream transport. Experimental measurements and numerical simulations are presented, demonstrating the effectiveness of the collimator system in reducing dark current.

Speaker: Yi-Chieh Chang (National Synchrotron Radiation Research Center)

TUP2670_edited_version.pdf

16:00 The design of the quasi-traveling wave parallel-coupled structure

A quasi-traveling-wave parallel-coupled (TWPC) accelerating structure is proposed for compact linacs requiring both high RF efficiency and improved frequency tolerance. In contrast to conventional standing-wave parallel-coupled structures, the proposed topology enables partial reflected power generated under detuned conditions to be redistributed through the feeding manifold and reabsorbed by downstream cavities. A 12-cell x-band TWPC structure operating in the $5\pi/6$ mode was designed using a cascaded waveguide feeding network. The structure achieves approximately 95\% unloaded RF power utilization with a 1.8 MW input power level. Beam dynamics simulations predict a 5 MeV energy gain with a 95%-bandwidth of 1.4 MHz.

Speaker: Yan Zhao (Tsinghua University)

TUP7603_edited_version.pdf

16:00 The essence factor to deteriorate the circular polarization radiation performance in APPLE-KNOT undulator

The APPLE-KNOT undulator forms composite magnetic fields by superimposing APPLE and KNOT fields with different period lengths. In this configuration, in which the APPLE field serves as the dominant component to approximate the target photon energy, while the KNOT field acts as an additional component to transversely deflect the electron beam off-axis. Although variable polarization modes can be realized with a low on-axis heat load, previous studies have observed a sharp reduction in flux and significant degradation of the polarization degree in the circular polarization (CP) mode. This paper discusses this phenomenon in detail from a theoretical perspective. The analysis reveals that the presence of an additional field with a longer period is the essence factor that inherently suppresses the radiation performance of CP mode. Theoretical findings are highly consistent with simulation results, demonstrating that selecting the KNOT field as the dominant component can effectively improve CP characteristics without significantly compromising the linear polarization performance.

Speaker: Binghao Zhang (National Synchrotron Radiation Laboratory, USTC)

TUP2708_edited_version.pdf

16:00 The First Beam Produced by A Conduction Cooled SRF Photogun

We are excited to report on the first beam produced by the world’s first conduction cooled SRF photogun. Over the past five years, Euclid, working in collaboration with Fermilab and Argonne National Laboratory, has been developing a continuous-wave (CW), 1.5-cell, MeV-scale, conduction-cooled SRF photogun operating at 1.3 GHz. The primary objective of this effort is to demonstrate ultra-stable electron beams for UEM/UED applications, enabled by the exceptional shot-to-shot stability achievable with SRF technology compared to room-temperature RF photoguns. Although SRF systems were historically too costly for industrial deployment, two recent advancements: Nb₃Sn coatings and conduction cooling, have dramatically reduced system complexity and operating costs. This SRF photogun can deliver true CW operation while dissipating only ~2 W of RF power, eliminating the need for a high-power RF system and significantly reducing facility footprint. This SRF photogun is also featured with a raised Nb3Sn backwall serving as the photocathode, removing the need for an external cathode insert. In this paper, we present the first beam results from this system along with its cooldown performance, Q-slope behavior, synchronization characteristics, and initial beam parameters.

Speaker: Chunguang Jing (Euclid Beamlabs)

TUV7301_edited_version.pdf

16:00 The Generation of Variable Polarization States in Terawatt X-Ray Free-Electron Lasers

Terawatt x-ray free-electron lasers (XFELs) represent the frontier in further development of x-ray sources and require high current densities with strong transverse focusing. In this paper, we investigate the implications/potentialities of TW XFELs on the generation of variable polarization states. The simulations indicate that significant power levels are possible with polarizations ranging from planar to circular and at high harmonics of the XFEL resonance across this range of polarizations. These XFELs can be an important coherent source of hard x-rays through the gamma ray spectrum. For this purpose, we use the MINERVA simulation code. Simulations indicate that, for the parameters under consideration, peak powers of the order 1 TW at the fundamental are possible over the entire range of polarizations.

Speaker: Henry Freund (University of Maryland, College Park)

16:00 The relativistic ponderomotive force under extreme focusing and direct vacuum laser modulation

When charged particles interact with laser fields,
they are usually thought to be pushed out from the regions of higher laser intensity
via the mechanism known as the ponderomotive force (PMF).
In contrast to the existing theories, we show that there exist several regimes
in which charged particles are drawn into the regions of strongly focused laser fields.
We derive a simple, covariant and relativistically correct expression
for the ponderomotive laser force that holds for arbitrary strength of field focusing, and for all particle velocities.
We predict three new physical effects: (1) non-relativistic reversal of PMF,
(2) focusing-dependent reversal of PMF, and (3) non-reciprocity of PMF for weakly-relativistic particle velocities.
We investigate an application of the PMF where a radially polarized laser is used to correct nonlinear deformations
in the transverse phase space of an electron bunch.

Whenever the laser-particle interaction is started or terminated in an abrupt way, the dominating first order effect
comes from the quickly oscillating motion at the frequency of the laser. We also propose an application of this
effect where the interaction is broken by a powerful THz kicker pulse, creating a train of microbunches that could be used for stroboscopic attosecond UED experiments.

Speaker: Johan Ribbing (Uppsala University)

16:00 The TEX facility upgrade at INFN-LNF

The TEX (TEst stand for X band) facility at INFN-LNF is a high-power RF test stand dedicated to the qualification of X-band components and accelerating structures for the EuPRAXIA@SPARC_LAB linac and related projects. An upgrade program is underway to extend its capabilities by increasing the available peak and average power, repetition rate, and operational flexibility for both X-band (11.994 GHz) and C-band (5.712 GHz) operation. The major intervention includes the installation of two new high-repetition-rate RF sources, one X-band and one C-band, together with dedicated waveguide distribution networks and improved diagnostics for breakdown detection, pulse shaping, and long-term stability studies. Moreover, the C-band station, with the integration in the bunker of a C-band RF photo-gun developed within the IFAST project, will serve as the first testbed for a full C-band high-brightness photoinjector, enabling experimental validation of compact injector schemes. These enhancements will allow parallel conditioning stations, advanced high-gradient tests of accelerating structures, and accelerated validation of RF components under realistic operating conditions for next-generation accelerators. The contribution will describe in detail the upgrade of the TEX facility and its future perspectives.

Speaker: Xianghe Fang (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati)

TUP7011_edited_version.pdf

16:00 The TIARA Collaboration: Shaping Two Decades of EU Support for Coordinated Accelerator R&D

European accelerator research involves more than 150 institutions –research and technology infrastructures, universities and industry– meaning that impactful R&D requires large, well-structured collaborations among all innovation actors. The European Commission’s framework programmes can play a strategic role in enabling these collaborations, but their effectiveness depends on coherent organisation at the community level.

Established in 2002 as ESGARD, the TIARA (Test Infrastructure and Accelerator Research Area) collaboration was created to promote and coordinate participation in EC calls. Its first major R&D project, CARE, began in 2004, followed by EuCARD, EuCARD2 and ARIES, and later by the innovation oriented I.FAST (2021-25). In parallel, TIARA supported 17 other projects, including design studies for new infrastructures and ESFRI-linked initiatives, securing €130 million in EC funding over 21 years, complemented by more than €200 million from partners.

This paper outlines TIARA’s vision to promote multi-platform collaborative accelerator R&D, broaden the impact of the European accelerator science and technology, and plans to strengthen its role within future EC programmes.

Speaker: Jose Manuel Perez (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas)

TUP8029_edited_version.pdf

16:00 Theoretical Analysis of a Novel Seeded Free-Electron Laser Scheme with the Same Layout as EEHG

Seeded free-electron lasers (FELs) are advanced, accelerator-based light sources characterized by high coherence and stability. In our previous research, we proposed an intelligent optimization framework for studying the micro-bunching process in seeded FELs. Using this framework for exploratory optimization, we identified a novel seeded FEL scheme. This scheme employs an optical layout identical to echo-enabled harmonic generation (EEHG), but by adjusting the parameters of the seed lasers and chicanes, it achieves bunching factors exceeding the theoretical limit of conventional EEHG. In this paper, using a representative set of realistic beam parameters, we demonstrate how this novel scheme induces a high harmonic density modulation in the electron beam. Then, we theoretically analyze this novel seeded FEL, presenting its underlying principles.

Speaker: Zhouyu Zhao (University of Science and Technology of China)

TUP2639_edited_version.pdf

16:00 Theoretical and Experimental Studies of the Injector for the SHINE Facility

Free-electron lasers (FELs) have promising application prospects in diverse fields such as physics, chemistry, and materials science. FEL facilities based on continuous-wave superconducting linear accelerators represent the state-of-the-art and future direction for FEL development. Generating high-brightness electron beams is essential for producing high-quality FEL pulses. The injector for the SHINE facility has now been commissioned, meeting all its design specifications. This paper focuses on the theoretical optimization of the injector's working point, presents key experimental results, and discusses ongoing efforts to achieve even lower beam emittance based on the established SHINE injector platform.

Speaker: Zipeng Liu (Shanghai Zhangjiang Laboratory)

16:00 Theory of cavity tuning with perpendicular biased ferrite

Yttrium-Iron-Garnet (YIG) ferrites have one-to-two orders of magnitude smaller magnetic permeability than Ni-Zn ferrites. In the frequency range above 10 MHz, Ni-Zn ferrites are too lossy to be useful. However in the frequency range roughly 30-120 MHz, YIG has high magnetic (and electrical) quality factor. Further, ferrites perpendicular-biased near saturation, have large incremental permeability due to the ferro-magnetic resonance (FMR). These properties presented an opportunity for effective wide-range RF cavity tuning, with low losses. Although high-Q narrow-range tuning was achieved, the promise of both wide tuning range and high Q was not achieved (despite more than a decade of development).This has never been explained, even prompting one author to suggest the magnetic Q (material property) varies quickly with frequency. Here we present a simple theory of cavity tuning with perpendicular biased ferrite (and FMR) that predicts tuning range and effective quality factor; and explains why the high Q cannot be maintained across a large range, and instead Q falls at low frequency.

Speaker: Dr Shane Koscielniak (TRIUMF)

TUP7302_edited_version.pdf

16:00 Towards a Community of Practice in Project Management of Particle Accelerator and Big-Science Projects: The AcceleratePM Initiative

Across Europe, several large-scale particle accelerator and big-science projects — each exceeding hundreds of millions of euros and extending over a decade — are under design or construction, with comparable initiatives underway in the US and China. Despite remarkable scientific achievements, many of them face cost and schedule drift, even when scientific performance targets haven’t been scaled down to maintain cost and timeline. Managing these complex, R&D-driven scientific facility projects requires approaches distinct from even the largest conventional infrastructure undertakings. Recognizing this need, a group of project management (PM) professionals active in particle accelerator initiatives has launched AcceleratePM*, the first international workshop dedicated to PM for accelerator and big-science projects. The first workshop, to be held at CERN in January 2026, will gather all major laboratories and projects to exchange methods, identify common challenges, and define best practices. This contribution presents the workshop scheme, themes, key-findings and planned outcomes, showcasing the largest recent projects – amongst which HL-LHC, ESS, FAIR, F4E – and aiming at informing the management of next-generation initiatives such as the Future Circular Collider (FCC). By building on common issues and most effective solutions, AcceleratePM intends to establish a lasting community of practice, shaping how large scientific projects are conceived, planned, and delivered.

Speaker: Giovanna Vandoni (European Organization for Nuclear Research)

TUP8032_edited_version.pdf

16:00 Towards Electron cooling of heavy, highly-charged ions after deceleration from 4 MeV/nucleon

The HITRAP decelerator facility has been designed to supply heavy, highly charged ions with low energy and momentum spread for use in physics experiments. It comprises several accelerator components for deceleration and a Penning trap for cooling ion bunches using electrons. The most exotic heavy, highly charged ions as for example bare Uranium ions are produced using the GSI accelerator complex by stripping at 100 MeV/nucleon and then decelerating and cooling them to 4 MeV/nucleon in the experimental storage ring (ESR). Finally, they are extracted in a single bunch towards the linear decelerator (HITRAP). Ions are decelerated in two steps from 4 MeV/nucleon to 500 keV/nucleon, and then to 6 keV/nucleon, in order to be injected into a Penning-Malmberg trap. Interacting with an electron cloud, which is also stored in this trap, reduces the momentum spread for efficient transfer at a few keV/q to the experiments.

Recently, the first signals of electron-ion interaction and energy transfer were observed using ions from a local test ion source (an EBIT). Progress towards cooling online ions will be presented, as well as the challenges involved, such as ion–electron plasma alignment, the detection and separation of incoming fast ions, the separation and suppression of charge exchange reactions during cooling, and the efficient transfer at low energy.

Speaker: Frank Herfurth (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Towards generation of orbital angular momentum THz radiation via dielectric wakefield acceleration

Dielectric wakefield acceleration, driven by electron beams, generates high-power, narrowband terahertz radiation via the coherent Cherenkov emission. While conventional dielectric-lined waveguides have been studied extensively for fundamental mode excitation, recent theory suggests higher-order modes carrying orbital angular momentum (OAM) can be deliberately excited in modified structures. We present progress toward generation of OAM-carrying THz radiation using tailored drive beam distributions and novel dielectric geometries at the UCLA MITHRA accelerator facility. OAM modes introduce transverse field components with helical wavefronts, enabling simultaneous longitudinal acceleration and transverse focusing of witness beams. This integrated functionality may simplify beamline design and mitigate beam breakup instabilities that currently limit efficiency in wakefield accelerators. We discuss the theoretical framework, particle-in-cell simulation results, experimental configurations, and newly developed diagnostics for OAM mode characterization.

Speaker: Jack Phillips (Particle Beam Physics Lab (PBPL))

TUP2346_edited_version.pdf

16:00 Towards integrated diagnostics for multi-stage dielectric laser acceleration: a conceptual study

Dielectric laser acceleration (DLA) enables compact, chip-scale accelerators. Recent demonstrations of multi-stage acceleration, alternating-phase focusing and interaction length in the millimeter range in dielectric nanostructures have verified the scalability of DLA concepts but the compactness places extreme demands on beam diagnostics due to submicron apertures, sub-fs bunch lengths and strong non-linear dynamics. To support the development of multi-stage structures and precise matching between stages, we explore diagnostic concepts that use the dielectric structures themselves. Tailored gratings can encode beam properties—such as bunch length—into emitted radiation, providing compact, high-resolution, on-chip diagnostics. Additionally to these hardware approaches, we propose to apply a machine-learning–based virtual diagnostic for DLA experiments. A neural network trained on 6D tracking simulations reconstructs key interaction parameters from the post-DLA electron beam and intermediate diagnostics and enables real-time optimization even in strongly non-linear regimes. Combining integrated dielectric diagnostics with ML-based reconstruction provides a scalable strategy for precise characterization and control of next-generation dielectric laser accelerators.

Speaker: Dr Thilo Egenolf (Technical University of Darmstadt)

TUP3017_edited_version.pdf

16:00 Towards Online-Tunable XFELs: Programmable Laser Shaping to Streaming End-Station Diagnostics

LCLS-II introduces MHz-rate operation and sub-femtosecond X-ray pulses, creating a need for high-rate control mechanisms at the photoinjector and diagnostic systems capable of extracting pulse structure on every shot. This work presents two key components toward meeting these requirements. First, a programmable photoinjector-laser system combining a spatial light modulator with dispersion-controlled nonlinear synthesis enables tunable UV temporal profiles compatible with the LCLS-II photocathode. Beamtime measurements demonstrate controllable modulation of the electron bunch and corresponding structure in the emitted X-ray pulses, including a triple-hump temporal pattern. Second, a high-throughput streaming front-end and machine-learning framework is developed for the Multi-Resolution Cookiebox diagnostic to rapidly extract attosecond X-ray pulse structure at high repetition rate. Together, these advances supply essential building blocks for future adaptive operation, including multiplexed experimental modes, live tuning of X-ray output, and integration with emerging modeling and optimization efforts.**

Speaker: Jack Hirschman (Stanford University, SLAC National Accelerator Laboratory)

16:00 Transport beam lines for laser-plama accelerators

Compared to RF accelerators, laser-plasma interaction produces beams with significantly larger emittance, energy spread, and divergence, necessitating dedicated transport line designs. This study investigates beam dynamics in various transport line configurations between plasma stages and towards the end users. Design and optimization of these lines are performed according to the requests on the beam parameters. Their capabilities and limits are also discussed.

Speaker: Laury Batista (Commissariat à l'Énergie Atomique et aux Énergies Alternatives)

TUP3032_edited_version.pdf

16:00 Two-Phase Flow Characterization for Cooling Accelerators in Space: Phase 1

High-power accelerators intended for space require more efficient cooling technologies. Flow boiling, a two-phase process, where water is boiled to dissipate the heat reduces size, weight, and power (SWaP) of thermal control systems (TCS).

The purpose of this work is to understand the flow and bubble dynamics of two-phase flows designed for space TCS. We present the experimental setup to measure velocity, temperature, and bubble dynamics at a spatial resolution of 5 μm/pixel in a 5 mm x 2 mm channel with one-sided heating. The setup includes three high resolution cameras for PIV (Particle Image Velocimetry), PLIF (Planar Laser-Induced Fluorescence), and shadowgraph to take measurements of velocity, temperature and to capture bubble images respectively. The raw and post processed data surrounding the bubbles generated in the flow is presented for the first time, showing the correlation between flow dynamics and heat transfer.

LA-UR-26-20793

Speakers: Bhavini Singh (Los Alamos National Laboratory), Taylor Roybal (Los Alamos National Laboratory)

16:00 Ultra-high dose-rate irradiation experiments at FLUTE

The linac-based test facility FLUTE at the Karlsruhe Institute of Technology (KIT) can be operated with a wide range of beam parameters, such as bunch charge, bunch length and repetition rate. This flexibility makes FLUTE an interesting test-bed for studies of accelerator-based ultra-high dose-rate irradiation with electron beams. Based on the time structure of the produced electron pulses, the instantaneous dose-rate can be tuned to exceed $10^{11}$ Gy/s with an average dose rate exceeding 40 Gy/s. At the same time, FLUTE can also provide average dose-rates closer to conventional rates in the order of 0.1 Gy/s.

Speaker: Dr Miriam Brosi (Karlsruhe Institute of Technology)

TUP8008_edited_version.pdf

16:00 Ultraviolet transverse shaping with structured-stochastic phase-plates for photocathode applications

Low-loss ultraviolet (UV) transverse shaping has emerged as a critical enabling technology for modern photoinjectors, with fused-silica phase-plates offering a robust alternative to conventional shaping methods. Building on our NAPAC2025 work, we introduce a new generation of enhanced UV phase-plates that use genetically seeded structured-stochastic designs and multi-level nanofabrication. These designs are initialized using spiral-zone-plate phase patterns and yield smoother transverse profiles at the photocathode while further reducing normalized emittance.
At LCLS-I, these phase-plates achieve a 25% emittance reduction (0.6 um to 0.45 um); beating expectations of 20% reduction predicted by Impact-T simulations. For AWA, we fabricated 2-inch fused-silica masks compatible with the upgraded gun and beamline optics. Leveraging multi-level nanofabrication capabilities at the Center for Nanoscale Materials, we produced plates with reduced phase quantization error, enabling high-quality shaping.
These results broaden the design space for low-emittance, jitter controlled photoinjector operation demonstrating the maturation of passive UV beam shaping into a facility-ready technology.

Speakers: Nicolas Burdet (SLAC National Accelerator Laboratory), Rachel Margraf-O'Neal (Argonne National Laboratory)

TUP2335_edited_version.pdf

16:00 Understanding the connections between grain growth and flux expulsion in low RRR niobium SRF cavities

The SRF community has shown that high temperature annealing can improve the flux expulsion of niobium cavities during cooldown. The required temperature will vary between cavities and different batches of material, typically around 800 C and up to 1000 C. However, for niobium with a low residual resistance ratio (RRR), even 1000 C is not enough to improve its poor flux expulsion. The purpose of this study is to observe the grain growth behavior of low RRR niobium coupons subjected to high temperature annealing to identify the mechanism for improving flux expulsion in low RRR cavities. We anneal the low RRR material up to 1200 C to understand the limits of flux expulsion performance. We observe that low RRR material experiences less grain growth than high RRR when annealed at the same temperature. We search for the limitations to grain growth in low RRR material and develop a diagnostic based on grain structure to determine the appropriate recipe for good flux expulsion. The results of this study have the potential to unlock a new understanding on SRF materials and enable the next generation of high Q/high gradient surface treatments.

Speaker: Katrina Howard (University of Chicago)

TUP7340_edited_version.pdf

16:00 Updated orbit stability evaluation for the Korea-4gsr Incoporating new mechanical and beam disturbance measurements

Beam orbit stability is a critical requirement for fourth-generation synchrotron radiation facilities. An initial evaluation for the Korea-4GSR quantified expected orbit disturbances from ground vibration, magnet current ripple, and energy oscillations. Since that baseline study, additional measurements and refined models have enabled a more accurate assessment. Newly acquired ground-motion data provide updated vibration spectra affecting magnet and girder motion. Orbit fluctuations induced by the EPU and the canted-ID configuration have been characterized and incorporated into the analysis. Vacuum-chamber vibration, previously unaccounted for, has also been measured to assess mechanical coupling to the beam. Using these updated disturbance sources, revised orbit-stability predictions have been obtained through beam-dynamics simulations. The study identifies the dominant contributors under current design conditions and discusses implications for orbit-feedback performance and mechanical design optimization.

Speaker: Junha Kim (Pohang Accelerator Laboratory)

TUP2630_edited_version.pdf

16:00 Using longitudinal strong focusing principle to lower particle beam energy spread locally in a storage ring

In this paper, we propose to use longitudinal strong focusing principle to lower particle beam energy spread locally in a storage ring. An example application of the proposed scheme in reversible Echo SSMB for high-power EUV radiation generation is presented. We believe strong focusing in the longitudinal dimension has a wide application potential.

Speaker: Xiujie Deng (Tsinghua University)

16:00 Using Stretching-Modulation-Compression effect to generate isolated few-femtosecond MeV electron bunches

Femtosecond electron beams serve as effective tools for investigating ultrafast dynamic processes in matter, providing complementary capabilities to femtosecond laser beams. We propose and demonstrate the feasibility of a scheme combining an undulator with THz modulation to generate isolated few-femtosecond electron bunches. We have developed a theoretical method that incorporates the transport dynamics of low-energy relativistic electrons interacting with the THz modulation field in the undulator and the space charge effects within the bunch itself. The results indicate that the proposed scheme can generate single isolated ultrafast electron bunches with kinetic energy 3 MeV, bunch length about 6 fs (rms) with core charge up to 0.1 pC. We have also evaluated the potential influence of several relevant physical quantities on the final bunch length and arrival time, and provided some scaling relations with respect to the initial bunch charges. The proposed scheme and the developed theoretical model presented may provide useful insights for generating few-femtosecond electron bunches or even shorter attosecond electron bunches in accelerator-based ultrafast electron facilities.

Speaker: Dr Weilun Qin (Institute of High Energy Physics, Chinese Academy of Sciences)

TUP2691_edited_version.pdf

16:00 Validation of an Improved Quadrupole Design for the 3 GeV SPS-II Storage Ring.

Achieving high beam stability in the 3 GeV SPS-II storage ring critically depends on the precision of its quadrupole magnets.This work presents a crucial phase of the magnet prototype development, which is central to fostering domestic high-technology manufacturing with Thai industry partners.Field measurements on the initial quadrupole design featuring removable poles revealed a critical engineering issue of significant multipole errors caused by mechanical pole rotation. This error was traced to the stresses and assembly error that occurred during pole removal and re-assembly for coil installation.To solve this specific problem, an improved quadrupole design was employed.The new symmetrical geometry eliminates the pole-removal step, thus intrinsically preventing the assembly error and significantly increasing structural stability and field quality. Coupled mechanical-magnetic analysis using ANSYS Workbench and Opera-3D confirms this approach. The simulations demonstrate that the improved design provides the required mechanical stability to minimize multipole field errors. The data presented validates this successful design change. The strict production tolerances were defined, and it is demonstrated precisely how the new design resolves the pole rotation issue. The presentation will feature a direct comparison of magnetic field measurements from both the initial and the improved prototypes, definitively verifying the enhanced performance necessary for SPS-II commissioning.

Speaker: Thongchai Leetha (Synchrotron Light Research Institute)

TUP7655_edited_version.pdf

16:00 WarpX simulation of the plasma meniscus effect in a neutral beam injection system

The US Department of Energy INFUSE collaboration between Realta Fusion and Lawrence Berkeley National Laboratory (LBNL) aims to extend WarpX towards high fidelity modeling of neutral beam injection (NBI) systems. WarpX is a parallel, open source, and portable particle-in-cell (PIC) code with an active developer community and demonstrated scalability. In this work, we implement and validate the plasma meniscus modeling for a positive ion source using first principle PIC simulations. These simulations are performed in the electrostatic mode with extraction electrodes represented as embedded boundaries. The upstream plasma reservoir is modeled using a thermal injection scheme with real electron mass to capture the correct sheath physics. These results and validations form a crucial basis for future extensions to negative ion sources and photoneutralization, enabling start to end NBI modeling within WarpX.

Speakers: Joey Eickman (Realta Fusion), Antoine Latrille (Realta Fusion)

TUP3068_edited_version.pdf

16:00 WaterFEL: Project Update on the New Canadian Infrared Free Electron Laser Facility

The WaterFEL is a national Infrared Free Electron Laser (IR FEL) facility that is funded and currently under development. Ground breaking for the new building that will house the facility has taken place at the University of Waterloo, Ontario, Canada. A design based on a similar facility at the Fritz Haber Institute in Berlin is being adapted for the WaterFEL accelerator and beamlines. The IR FEL machine will consist of an electron linac with energy up to 50 MeV and two undulators to create light for two beamlines, one in mid IR and one in far IR. The major components are currently being procured and should be completed by 2027. This is a brief report on the project and some of the design parameters.

Speaker: Prof. Mark Boland (University of Saskatchewan)

TUV2303_edited_version.pdf

16:00 X-ray frequency combs generation using echoenabled harmonic generation free electron laser

Optical frequency comb (OFC) technology provides precise measurement tools for optical frequencies, leading to revolutionary changes in the field of optics.OFCs consist of a series of uniformly spaced spectral lines resembling the teeth of a comb, and they have found widespread applications in timing, precision spectroscopy, and fundamental physics.Extending this technology into the EUV to X-raydomaintoachieve ultra-high precision detection of molecular and atomic structures has been a significant challenge faced by the scientific community.The next generation of light sources—free electron lasers—holds promise for addressing this challenge.By positioning different groups of undulators at various harmonic resonances within the EEHG-FEL, periodic modulation of the electron beam will be formed, which, with the appropriate parameter settings, will enable the generation of fully coherent optical frequency combs

Speaker: Lanpeng Ni (Shanghai Institute of Applied Physics)

16:00 Zeptosecond γ-Ray Pulses Generation via FEL-Driven Microbunching and Laser-Compton Scattering

The ultrashort pulse concept, known as "measurement-before-destruction," pioneers ultrafast probing of sensitive states by allowing signal capture before significant laser-induced changes occur. While Free-Electron Lasers (FELs) drive progress in attosecond X-ray generation for electron dynamics, the next frontier—time-resolved nuclear dynamics—demands sub-attosecond to zeptosecond pulses at MeV energies, a regime where standalone FELs face fundamental resource and physical limitations.
To overcome these barriers, we propose a novel methodology combining FEL technology with laser Compton scattering to generate ultrashort (hundreds of zeptoseconds) pulses with extremely high photon energies (MeV to hundreds of MeV). This approach effectively leverages Compton scattering to produce high-quality gamma rays while bypassing the pulse broadening caused by FEL slippage. This innovation offers the potential to investigate previously inaccessible level densities in compound nuclei and nuclei far from stability, and to advance studies in fundamental quantum measurement phenomena such as the Quantum Zeno and Anti-Zeno Effects, opening new possibilities beyond nuclear physics.

Speaker: jinke Xiong (Shanghai Institute of Applied Physics, Chinese Academy of Sciences)

20:00 → 22:00 Main Reception

Wednesday 20 May

09:00 → 10:30 MC1 : Colliders and Related Accelerators

09:00 RHIC's quarter-century of colliding beam operation

As a cornerstone of US Nuclear Physics, the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory (BNL) concluded operations this year, marking the end of a remarkable 25-year era of colliding beam research. Originally designed to deliver ion-ion collisions over a broad range of energies, including species of unequal mass, RHIC’s capabilities were later expanded to support a unique and highly successful polarized proton program. Sustained technological innovation and continuous performance optimization significantly enhanced the collider’s flexibility, efficiency, and scientific reach. Major advances included bunched-beam stochastic cooling and injector upgrades, which enabled nearly a 50-fold increase in luminosity over the original design; RF-based electron cooling, which extended the accessible energy range; and head-on beam-beam compensation using electron lenses. For the polarized proton program key developments included the deployment of Siberian Snakes, resonance mitigation techniques, and precision beam control that enabled high proton polarization at high beam energies. In the following, we review the evolution of RHIC performance, summarize major advances in accelerator science achieved at RHIC, and highlight selected, highly impactful improvements that contributed to sustained high-performance operation.

Speaker: Michiko Minty (Brookhaven National Laboratory)

WEI1T01_edited_version.pdf

09:30 First synchrotron injection attempt into the SuperKEKB HER

A synchrotron injection scheme for the SuperKEKB high-energy ring (HER) was implemented and experimentally evaluated. The lattice at the HER injection point was configured to provide a large horizontal dispersion of –1.6 m, and the sextupoles were optimized accordingly. Because an abort system is located near the injection point, the optics design was constrained to ensure compatibility with the abort-system requirements. Optics solutions were developed to enlarge the dynamic aperture for interaction-point β_y* values of 81 mm, 8 mm, 3 mm, and 1 mm. A systematic procedure of the injection parameters has been established using a turn-by-turn BPM in the ring. The betatron components of the injected beam was successfully removed.
Using the optimized optics, synchrotron injection into the HER was successfully demonstrated, followed by the establishment of stable beam–beam collisions and the production of luminosity. As the injection repetition rate was increased, however, an unexpected degradation in injection efficiency was observed, leading to the suspension of the study. These experimental results and possible mechanisms that contributed to the observed injection degradation will be reported.

Speaker: Naoko Iida (High Energy Accelerator Research Organization)

WEO1T01_edited_version.pdf

WEO1T01_talk_edited_version.pdf

09:50 Performance Strategy for the First Years of the EIC Science Program

The Electron-Ion Collider (EIC) will begin science operations with a staged machine configuration that imposes well-defined accelerator-physics constraints on achievable luminosity and beam parameters. This paper presents the performance strategy that supports the first 3-5 years of the EIC Science Program. We outline the accelerator-physics activities required to deliver high-repetition-rate electron beams, heavy-ion beams, deuterium, polarized protons, and ³He, together with the performance evolution of electron and hadron polarization systems, spin rotators, bunch patterns, and longitudinal emittance control. The paper highlights the year-by-year integration of new machine capabilities, including progressive increases in beam intensity and average luminosity required to meet evolving science objectives. This framework defines the accelerator-physics roadmap for performance delivery and sustained operation of the EIC Science Program.

Speaker: Alexei Blednykh (Brookhaven National Laboratory)

WEO1T02_edited_version.pdf

WEO1T02_talk_edited_version.pdf

10:10 Near Resonance Polarization Modulation (NRPM), a Novel Method for High Precision Beam Energy Measurement in Storage Rings

We propose Near Resonance Polarization Modulation (NRPM), a novel method for high-precision beam energy measurement in storage rings. In this technique, a constant-frequency AC dipole is applied near the spin precession frequency, driving the beam spins coherently. The spin tune can be reliably extracted from the time-dependent polarization signal, enabling a very high-precision determination of the beam energy. Its performance has been demonstrated using the Future Circular Collider e+e- (FCC-ee) Z-pole lattice, exploring a range of configurations including AC dipole strengths and initial polarization levels. The method exhibits robustness against lattice imperfections. Compared to the traditional resonant depolarization (RDP) technique and the free spin precession (FP), NRPM offers significantly improved precision, greater tolerance to systematic uncertainties, and simplified operational procedures. Beyond the FCC-ee case study, NRPM is broadly applicable to high-precision energy determination in modern storage rings. The superior precision offered by this technique will significantly advance the state-of-the-art in beam energy measurement, with critical applications in high-energy physics and the measurement of fundamental constants.

Speaker: Yi Wu (École Polytechnique Fédérale de Lausanne)

WEO1T03_edited_version.pdf

09:00 → 09:30 MC8 : Applications of Accelerators, Engagement with Industry, Technology Transfer and Outreach

09:00 Accelerator-based lithography and the Induction Storage Ring Light Source

Techniques for generating light with particle accelerators have so far proven difficult to industrialize. Accelerator-based light sources are typically housed at universities and national laboratories, which prioritize fundamental scientific discovery over economic and operational considerations like cost efficiency and 24/7 consistency. By contrast, EUV lithography in semiconductor manufacturing relies on laser-produced plasma (LPP) sources - a dependable but mature technology whose limited output power and inability to operate at shorter wavelengths constrain the industry. An accelerator-based EUV light source could be transformative for the industry, but efforts to date have yet to yield a practical solution. This talk reviews past and ongoing attempts to develop accelerator-based light sources for semiconductor manufacturing and introduces a concept under exploration at SLAC National Accelerator Laboratory – the isochronous induction-cell storage ring - which may enable coherent emission of EUV light via steady-state microbunching (SSMB).

Speaker: Michael Ehrlichman (SLAC National Accelerator Laboratory)

WEI8M01_talk_edited_version.pdf

09:30 → 10:30 MC4: Hadron Accelerators

09:30 Development and commissioning of normal conducting ion linacs: the INFN experience.

Normal conducting proton and ion linacs are vital components for applications in medical treatments, research, and industrial uses. As front-end of high-power proton linacs, they play a critical role in the initial acceleration and conditioning of the proton beam, setting the foundation for successful beam acceleration and high-power performance. INFN is engaged in different projects for development, construction and commissioning of Normal Conducting Linacs: the DTL of ESS Lund, the RFQ for the SPES facility at LNL, the CW RFQ for Lipac/IFMIF in Japan and the RFQ for IFMIF/DONES in Spain. More recently the group has been involved in the Next Generation EU project ANTHEM, for an accelerator based BNCT facility in Italy. The parallel development of these projects, although in various stages, has allowed a synergic application of common solutions between projects, the development of new tools for design and analysis, the optimization of experiences and lessons learned. Building on this experience, new ideas and applications have emerged, including the feasibility study of a compact accelerator-based neutron source and the "Alpha-DTL": a DTL-based linac for alpha particle acceleration at variable energy.

Speaker: Francesco Grespan (Istituto Nazionale di Fisica Nucleare)

WEO4M01_talk_edited_version.pdf

09:50 Beam tests of a permanent magnet medical accelerator arc from 10-250MeV

The FLASH hadron therapy accelerator proposed by Trbojevic uses permanent magnets with nonlinear fields to allow rapid cycling from 10 to 250MeV while keeping the ring tune constant. A test beamline of four cells from this ring (22.5 degree angle) was built at BNL and tested at the NSRL facility with protons and at the Tandem Van de Graaff with deuterons. The magnets consist of 24 neodymium-iron-boron (NdFeB) wedges magnetised in different directions and arranged to produce the required nonlinear field profile across the oval aperture for the beam movement, with fields of up to 1.85 Tesla. Beams were transmitted at all rigidities tested over a 5.3x momentum ratio, with output location moving systematically with energy as required.

Speaker: Stephen Brooks (Brookhaven National Laboratory)

Brooks_IPAC26_FFAfixedtuneProtonTherapy.pptx

10:10 GANIL-SPIRAL2 4 years in operation

Since 2019, the SPIRAL2 SC linear accelerator at GANIL (Grand Accélérateur National d’Ions Lourds) produces pulsed to CW ion beams from A/Q=1 to 3.
Beam time during the last 4 years was mainly dedicated to experiments in the NFS room with D+ at energies from 1 to 40 MeV, frequently using the bunch selector allowing neutron time-of-flight measurements.
Part of the beam time was also used to prepare the linac for the S3 experimental room commissioning accelerating heavy ions up to A/Q=3 from 0.75 to 14.5 MeV/A.
This paper presents the beam time sharing over the four years of operation.

Speaker: Omar Kamalou (Grand Accélérateur Nat. d'Ions Lourds)

IPAC2026_Kamalou_SPIRAL2_final_AKO.pdf

WEO4M03_talk_edited_version.pdf

10:30 → 11:00 Coffee break

11:00 → 12:30 MC3 : Advanced acceleration techniques and novel particle sources

11:00 Controlled injection and acceleration of 10 GeV-class electron beams in a laser wakefield accelerator

We measure the high-intensity laser propagation throughout meter-scale, channel-guided laser-plasma accelerators by adjusting the length of the plasma channel on a shot-by-shot basis, showing high-quality guiding of 500 TW laser pulses over 30 cm in a hydrogen plasma of density 𝑛≈10^17  cm−3. We observed transverse energy transport of higher-order modes in the first ≈12  cm of the plasma channel, followed by quasimatched propagation, and the gradual, dark-current-free depletion of laser energy to the wake. We quantify the laser-to-wake transfer efficiency limitations of currently available petawatt-class lasers and demonstrate via simulation how control over the laser mode can significantly improve beam parameters. Using 21.3 J of laser energy, and triggering localized electron injection, we observed electron bunches with single, quasimonoenergetic peaks up to 9.2 GeV with charge extending beyond 10 GeV.
Reference:
Picksley et al., Phys. Rev. Lett. 133, 255001 (2024)

Speaker: Alex Picksley (Lawrence Berkeley National Laboratory)

WEI3T01_talk_edited_version.pdf

11:30 Progress Towards High-Repetition-Rate Plasma Wakefield Acceleration at FLASHForward

Radiofrequency linacs accelerate thousands of bunches per second, which should be matched by beam-driven plasma wakefield accelerators (PWFAs) if their benefits as high-acceleration-gradient energy boosters are to be fully exploited. However, demonstrations to date have accelerated only ~10 bunches per second. At FLASHForward, key issues are being solved to bridge this gap. Analytic models have been developed to show how to generate bunch pairs from the photocathode with the longitudinal shape optimised for plasma acceleration, thus reducing stray radiation compared to a collimator system. To deal with large energy depositions from rapid plasma creation and acceleration events benchmarked models have been built to determine the heating of the plasma source at kHz repetition rates, so that remedial measures can be developed. Furthermore, we have seen that ionisation induced by the wakefield-perturbed plasma can limit the maximum repetition rate. Finally, PWFAs must produce large energy gains for photon science or particle physics applications. We recently demonstrated acceleration of bunches from 1.2 to > 1.7 GeV over 0.5 m of plasma, with < 2% energy spread.

Speaker: Dr Judita Beinortaitė (Deutsches Elektronen-Synchrotron DESY)

WEO3T04_edited_version.pdf

WEO3T04_JuditaBeinortaite.pdf

11:50 Short-pulse driven photogun for very hard x-ray free-electron laser

High gradient radio frequency (rf) driven photoguns are photoemission electron sources that have important applications for accelerator-based instruments, such as light sources and electron microscopy. Numerous efforts have been made to push for even higher field gradient while suppressing rf breakdowns. We propose the Compressed Ultrashort Pulse Injector Demonstrator, a 1.6 cell photogun driven by nanosecond high power rf pulses to achieve high gradients with low breakdown rate. This photogun is powered by ultrashort pulses from a rf pulse compressor and a high power klystron. This presentation focuses on the work of the CUPID photogun for generating bright electron beams to drive x-ray free-electron lasers (FELs) at 40 keV photons or higher. We first show the design of CUPID photogun, followed by its capability of bright beam generation when forming a photoinjector with a superconducting solenoid and downstream linacs. We then show start-to-end simulations of the existing LCLS copper accelerator free-electron laser with CUPID photogun as a drop-in replacement to demonstrate its improvement in delivering hard x-rays at mJ level pulse energy. Finally, we show preliminary high power rf testing of CUPID prototypes and plans for electron beam generation.

Speaker: Wei Hou Tan (SLAC National Accelerator Laboratory)

WEO3T02_edited_version.pdf

WEO3T02_talk_edited_version.pdf

12:10 A Portable Muon Source for artificial muon muography

Muography is a useful technology for non-destructive inspection of a large-scale structure. Muography with cosmic ray muons has limitations such as low rates, particularly low muon rates in the horizontal direction, and energy spreading, which require long observation times and limit its resolution. Worldwide, large structures such as bridges built during the economic development period of the 1950s-1960s have reached the end of their useful life, and the principle of preventive maintenance is being applied to save the resources, by understanding their interiors and renewing them with priority given to structures that have deteriorated. At this time, a technology of non-destructive inspection applicable to such large structures is required, and Muography using a portable artificial muons source is a promising candidate for this purpose. In this presentation, the results of the investigation of the portable artificial muon source will be presented.

Speaker: Masao Kuriki (Hiroshima University)

WEO3T03_edited_version.pdf

WEO3T03Slides.pdf

WEO3T03Slides.pptx

WEO3T03_talk_edited_version.pdf

11:00 → 12:30 MC5 : Beam Dynamics and EM Fields

11:00 Overview of crab cavities for light sources and particle colliders

RF systems for transverse deflection, also known as crab cavities, have been considered for many accelerator facilities in the last decade. This contribution reviews their application to storage ring light sources and colliders, both circular and linear. The constraints for the implementation of crab cavities in these accelerators and the technical challenges, with a focus on the recent advances in transverse deflecting superconducting cavities, are discussed.

Speaker: Rama Calaga (European Organization for Nuclear Research)

WEI5M01_edited_version.pdf

WEI5M01_talk_edited_version.pdf

11:30 Beam Dynamics Challenges and Optics Development for the PERLE Multi-Turn ERL

PERLE is a high-current, multi-turn Energy Recovery Linac currently entering its construction phase, being developed as a demonstrator for advanced ERL technology and future high-power electron facilities. The staged construction and commissioning schedule foresees single-turn energy recovery in 2029, with full three-turn operation planned for 2031. Achieving these milestones requires an optics and beam-dynamics strategy that accommodates strong space-charge effects in the injector/merger, coherent synchrotron radiation in the arcs, and very tight loss tolerances characteristic of high-current ERLs.

We present PERLE’s current status and the latest optics design for the one-turn commissioning mode and the nominal three-turn configuration. The lattices are evaluated using multi-physics tracking to assess collective effects, error sensitivity, and operational stability. Particular emphasis is placed on identifying workable settings that support high-current transport and robust energy recovery across the different operational stages.

This contribution provides an update on construction and commissioning timelines, outlines the main beam-dynamics challenges for staged operation, and summarizes recent progress in optics development. The results contribute to defining the operational basis for PERLE and provide insight relevant to the design studies of future multi-turn ERL facilities.

Speaker: Alex Fomin (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

WEO5M01_talk_edited_version.pdf

11:50 Transport of dark current through the Linac to End Station A beamline at LCLS

The recently-commissioned Linac to End Station A (LESA) beamline was designed to deliver high-energy electrons to experiments in End Station A, such as the Light Dark Matter eXperiment (LDMX). Since LDMX requires single electrons at a high repetition rate, dark current from the 186 MHz LCLS-II electron gun provides a convenient low-current source that can be extracted parasitically from the beam switchyard (BSY). However, the orbit and phase space distribution of the dark current differ from those of the main photocurrent beam. Furthermore, the quantity and behavior of the transmitted dark current change substantially each time the cathode is changed, as well as with machine tuning changes upstream. Due to these factors, it is useful to have an efficient method of reestablishing the orbit of the dark current in LESA in response to these changes. Since the dark current is too low to observe with the LESA BPMs (often only a few electrons per RF bucket), we must use a more limited set of diagnostics to characterize its orbit near the BSY and establish its transport to ESA.

Speaker: Sean Littleton (SLAC National Accelerator Laboratory)

WEO5M02_talk_edited_version.pdf

12:10 On the optimization of the non-linear performance of 4th-generation light sources

The successful non-linear performance of 4th-generation light sources can be supported through a proper design of the linear lattice. However, important quantities like the injection efficiency and the beam lifetime depend on the optimization of non-linear magnetic fields like sextupoles, octupoles (and sometimes decapoles) in the lattice and therefore on numerical optimization. The underlying quantities to be maximized, are the limits of stable particle motion in the injection plane, the dynamic aperture, and the Touschek lifetime, i.e. the momentum acceptance of the ring. Commonly, multi-objective genetic algorithms are used for the optimization. Alternatively, the resonant driving terms can be minimized. Both approaches need to take the uncertainties introduced by manufacturing tolerances or jitters in the real machine, into account. Using the parameters of the BESSY III storage ring at HZB, Berlin, this paper compares both approaches and tries to develop an efficient optimization strategy for the upcoming technical design phase.

Speaker: Bettina Kuske (Helmholtz-Zentrum Berlin für Materialien und Energie)

WEO5M03_edited_version.pdf

WEO5M03_talk.pdf

WEO5M03_talk.pptx

12:30 → 14:00 Lunch break

14:00 → 16:00 Engagement with Industry Session

14:00 Introduction Topic 1

Sustainability is becoming a key requirement for projects and developments, from design and procurement to operation, and end-of-life management.
Direct and indirect emission, transport are two topics for which key performance indicators are today well identified. On the other end, procurement which contribute largely to green house gas emission is more difficult to evaluate.
This session should explore sustainability issues during the full project lifecycle including procurement and discuss how industry can provide essential lifecycle information and ensure compliance.

Speaker: Jean-Luc Revol (European Synchrotron Radiation Facility)

WEU00_talk_edited_version.pdf

14:05 Sustainability into pre-procurement and procurement: CERN's recent journey.

Sustainability is becoming a key requirement for large-scale research infrastructures, supported in Europe by a demanding regulatory framework with directives and guidance on best practices.
This presentation will describe the evolution from the Environmentally Responsible Procurement Policy project to the CERN Sustainable Procurement project outlining how the Organization progressively embedded sustainability considerations into pre-procurement and procurement phases. In this context, risks in the supply chain, such as disruptions and price volatility, make sustainable procurement an essential lever for CERN resilience.
A particular focus is given to supplier engagement, including the development of a methodology to segment suppliers and define tailored action plans, aiming both to strengthen sustainability across the supply chain and to learn from the most sustainability-mature suppliers.

Speaker: Mr Cennini Enrico (European Organization for Nuclear Research)

WEU01_talk_edited_version.pdf

WEU01_talk.pptx

14:20 Sustainability Issues in Asian Accelerator Laboratories

The sustainability of particle accelerators in Asia represents a complex challenge involving environmental, economic, scientific, and geopolitical considerations. As Asian nations expand investments in large-scale accelerator facilities such as synchrotrons, cyclotrons, and linear accelerators, these infrastructures are increasingly recognized as essential tools for scientific innovation, industrial development, medical research, and technological competitiveness. This presentation examines the sustainability of particle accelerators across Asia by analyzing their contributions to research and development alongside the challenges associated with energy use, carbon emissions, resource management, and technological obsolescence. Furthermore, the study highlights emerging strategies such as energy-efficient accelerator designs, renewable energy integration, and multipurpose research applications that may improve sustainability outcomes. The analysis concludes that while particle accelerators present significant environmental and economic demands, their broader contributions to scientific advancement, healthcare, clean energy innovation, and industrial modernization can support sustainable development when managed through strategic planning, technological innovation, and international cooperation.

Speaker: Ping He (Institute of High Energy Physics)

WEU04_talk_edited_version.pdf

14:35 Sustainability meets reality: the industry perspective

RI Research Instruments is a supplier to particle accelerator projects all over the world. We build the research instruments needed for a sustainable world and we also build an ever more sustainable company.
Our actions and ambitions are laid out in our sustainability report. They strive for reduction of our CO2 footprint and contributions to the UNs Sustainable Development Goals (SDG).
In this presentation we focus on the dialog needed between the operators of particle accelerators (customers) and the companies like RI delivering to them (suppliers). Collectively we need to find ways to report sustainability efforts, include sustainability in the design of particle accelerators and incentivize such efforts when awarding contracts. We also need to find ways how savings in operations cost (lower electricity consumption etc.) can be balanced against higher investment cost.
We will present our recent activities, such as investment in brand new buildings with high energy efficiency and state-of-the art handling of chemicals, transition to electrical cars and others.

Speaker: Benjamin Bromberger (RI Research Instruments GmbH)

RI_Sustainability IPAC 2026.pdf

WEU05_talk_edited_version.pdf

14:42 SUSTAINABLE PROCUREMENT AND PROJECT LIFECYCLE - Feedback from industry SIGMAPHI

Based on over 20 years of experience in technical procurement and industrialization of particle accelerator systems, this presentation addresses the practical challenges of implementing sustainable procurement strategies in highly constrained industrial environments.

Through concrete feedback from major international projects, including collaborations with research institutes and fusion programs, it highlights the gap between sustainability objectives and operational realities such as performance requirements, cost constraints and tight delivery schedules.

The presentation focuses on actionable approaches including local sourcing, supplier consolidation, material recycling optimization, and logistics rationalization. It also discusses the limitations encountered when sustainability targets conflict with technical specifications or project constraints.

Finally, it proposes pragmatic ways to integrate sustainability into procurement and project lifecycle management without compromising industrial performance.

Speaker: Mr VINCENT SIGALO (SIGMAPHI S.A.)

15:00 Introduction Topic 2

This topic will address current challenges in attracting, training, and retaining highly skilled technical staff for accelerator development and operation. Insights will be shared by laboratories and industry.
Accelerator schools will be presented.
The objective is to discuss how laboratories, universities, and companies can encourage the next generation to pursue careers in accelerator-related fields. Statistics should be provide on how many students are trained and remains in the field after their training.

Speaker: Jean-Luc Revol (European Synchrotron Radiation Facility)

WEU09_talk_edited_version.pdf

15:05 Joint Universities Accelerator School: History and successes

Since 1994, the Joint Universities Accelerator School (JUAS) has provided postgraduate education in the science and technology of particle accelerators to nearly 1,600 students. Most have earned credits toward Master's or Doctoral degrees at our Partner Universities across Europe, while others—whether from universities worldwide or early-career professionals—have sought to deepen their expertise and skills. Many JUAS alumni have gone on to build successful careers in leading laboratories, industry, and academia. This paper explores the origins, history, and achievements of this unique school.

Speaker: Elias Métral (European Organization for Nuclear Research)

WEU03_talk_edited_version.pdf

WEU03_talk.key

15:25 Accelerator Workforce Development and Training for Labs and Industry in the United States

The US Particle Accelerator School (USPAS) is celebrating its 45th anniversary this year. The USPAS provides training and workforce development in the science and technology of charged particle accelerators and associated systems. Historically, the school attendees primarily represented universities and national laboratories with relatively few from industry. However, over the past few years, several new companies based on accelerator technology have been founded in the US, primarily to address major technology areas such as semiconductor manufacturing and testing, production of radioisotopes, fusion and fission energy production, and medical applications. I will discuss how the USPAS is responding to the needs of industrial accelerator companies and continuing to support laboratory needs.

Speaker: John Byrd (Argonne National Laboratory)

15:40 From Students to Experts ​ – an Industry Perspective

Topics addressed:
Who we are: Cosylab was founded in 2001 as a spin-off of the Josef Stefan Institute, established by a physicist and his students. Today, we have about 270 people, with around one-third physicists and two-thirds engineers and computer scientists.
How we build experts: To contribute effectively to accelerator projects, our team needs four things: technical skills, knowledge of the accelerator field, strong engineering practices, and people skills.
How we train: We use mentorship, internal lectures, external accelerator schools like the CERN Accelerator School EPICS course, and hands-on commissioning work with our supply chain partners.
How we give back: We offer training courses for labs and institutes, work with universities through EU consortia, and participate in the Marie Curie Doctoral Network.
The ecosystem argument: We are all part of the same ecosystem, so working together is essential to close the talent gap.

Speaker: Anna Balažic (Cosylab)

From student to expert.pdf

WEP1303_edited_version.pdf

WEP1303_edited_version.pdf

WEP1303_edited_version.pdf

WEP1303_edited_version.pdf

14:00 → 15:40 MC5 : Beam Dynamics and EM Fields

14:00 Manipulating and diagnosing electron beam with cross-plane coupling in transverse and longitudinal phase spaces

Manipulating phase space of the beam distribution is increasingly important not only for advanced accelerator concepts but also for X-ray free electron lasers (FELs). In the case of hadron cooling, a prime example is magnetized beams, where cross-plane correlations between two transverse phase spaces dominate the beam dynamics. Precisely controlling these cross-plane couplings—either by introducing or eliminating them in beams with high transverse emittance ratios—is highly relevant. In the case of the FELs, specific examples include the suppression of double-horn shape in the longitudinal phase space and non-linear bunch compression while preserving transverse emittance, where understanding the phase space with coupled information is advantageous for its control against collective effects. These sophisticated manipulations rely on precise phase space diagnostics, for which we apply an AI/ML-based phase space reconstruction algorithm capable of accurately determining all cross-plane correlations. We present a comprehensive analysis of beam dynamics, supported by experimental demonstrations of both the beam manipulation techniques and the phase-space reconstruction methodology.

Speaker: Seongyeol Kim (Pohang University of Science and Technology)

WEI5M02_talk_edited_version.pdf

14:30 Realization of high-intensity beams with smaller emittance without a transverse feedback system

The RCS at J-PARC is a kicker-impedance-dominant machine, which exceeds the impedance budget from a classical viewpoint. However, we have achieved a 1-MW beam without any transverse feedback by fully utilizing the indirect space charge effect to suppress beam instabilities.
Although the indirect space charge effect is beneficial, the beam instability can still occur in a high-intensity beam with a smaller transverse emittance. To address this, we installed diode stacks and resistors at the ends of the four kicker power cables and have successfully conducted routine operations.
This approach theoretically opens the door to achieving high-quality, higher-intensity beams, including a 2-MW beam, as no transverse feedback is required.

Speaker: Yoshihiro Shobuda (Japan Proton Accelerator Research Complex, Japan Atomic Energy Agency)

WEI5M03_edited_version.pdf

WEI5M03_talk.pdf

WEI5M03_talk.pptx

15:00 Optics Correction for Fourth-Generation Light Sources and Future Colliders

Accurate lattice-optics correction is essential for achiev-
ing the design performance of modern light sources and
future circular colliders targeting ultra-low emittances. Such
machines rely on strong magnets that are highly sensitive
to field and alignment errors. In this work, we investigate
approaches for the correction of the linear optics of sev-
eral accelerators. The study includes selecting appropriate
correction steps, defining the fitted parameters, and design-
ing optics correction schemes tailored to the characteristics
of each accelerator. Experimental tests were performed at
ESRF-EBS, while the simulation studies for PETRA IV,
FCC-ee and SOLEIL II investigate the achievable perfor-
mance of future machines.

Speaker: Elaf Musa (Deutsches Elektronen-Synchrotron DESY)

WEO5M04_edited_version.pdf

15:20 Low-emittance, Low-charge optimization of the Argonne Wakefield Accelerator for the Nanopatterned Microbunching Experiment

Low-emittance microbunched electron beams are a key ingredient in free-electron lasers (FELs), facilitating gain and coherence in radiation production. It has been proposed, such as by the Compact X-ray FEL (CXFEL) group at Arizona State University, that nano-scale microbunching could be produced by rotating transverse beamlets into the longitudinal plane. Such a technique could make short-wavelength FELs much more compact, reducing cost. Thus, a collaboration has been formed to test this principle using the emittance exchange (EEX) beamline of the Argonne Wakefield Accelerator (AWA). ** This experiment will take micro-scale transverse modulations on a TEM grid and produce mico-to-nano scale microbunches. Performing this with AWA’s 40 MeV electron beam will require low normalized emittance (~50 nmrad), and low charge (~1pC) electron bunches that are not commonly produced at AWA. These proceedings will detail our work to produce and characterize this low emittance in the AWA beamline.

Speaker: Rachel Margraf-O'Neal (Argonne National Laboratory)

WEO5M05_edited_version.pdf

15:40 → 16:00 MC6 : Beam Instrumentation, operation Controls, Feedback and Operational Aspects

15:40 AI and machine learning techniques for LNL accelerators

The application of Artificial Intelligence (AI) and Machine Learning (ML) to particle accelerator systems has emerged as an effective strategy for managing complex operations and enhancing performance. At INFN-Legnaro National Laboratories (INFN-LNL), both offline and online AI/ML-driven approaches have been developed to improve beam dynamics, reduce setup times, and increase overall accelerator efficiency.

Offline efforts focus on surrogate modeling of complex facilities such as ANTHEM BNCT, as well as on virtual diagnostics implemented using supervised neural operators. By combining these tools with AI/ML optimization algorithms, new design and commissioning strategies are being explored to further enhance beam quality and operational performance.

In parallel, online real-time optimization strategies based on Bayesian Optimization (BO) has delivered promising results. Notably, at the PIAVE-ALPI superconducting accelerator, the application of BO improved beam transmission up to 85%, a significant increase compared to the typical operational average of 35%. These advances demonstrate the growing impact and future potential of AI/ML technologies in accelerator science and operations.

Speaker: Ysabella Kassandra Ong (Istituto Nazionale di Fisica Nucleare)

16:00 → 18:00 Poster session

16:00 1 MW Beam Power in the Fermilab Main Injector

In June 2024, the Fermilab Main Injector recorded its greatest one hour average beam power delivered to NuMI. The record 1.018 MW power was the culmination of years of work, involving upgrades to various systems to allow for greater beam intensity, better loss control and faster ramping of the machine. Following the record achievement, the Main Injector complex suffered a series of failures that have prevented NuMI beam. This paper will discuss the beam power record, Main Injector's recovery efforts, and future plans for even higher beam power.

Speaker: Kyle Hazelwood (Fermi National Accelerator Laboratory)

16:00 A Bayesian Optimization Study of the Longitudinal Localized Excitation Slow Extraction for the XiPAF-Upgrading Synchrotron

The longitudinal localized excitation slow extraction method reduces the energy spread of the extracted beam by applying transverse excitation exclusively within specific phase intervals at the edges of the longitudinal phase space of the bunch. For localized square-wave excitation, conventional amplitude modulation formula struggles to achieve uniform beam spill, while the temporal uniformity of the extracted beam is crucial in radiotherapy and related physics experiments.
The XiPAF-Upgrading Synchrotron (with a circumference of 39.96 m), developed from Xi’an 200 MeV Proton Application Facility, serves as a dedicated platform for the study and evaluation of single-event effects on core electronics for astronautics. We simulated the localized square-wave excitation slow extraction process using the SynTrack particle tracking code based on the XiPAF-Upgrading Synchrotron's parameters to extract low energy spread beam. Furthermore, a Bayesian optimization method was employed to refine the amplitude modulation curve of the excitation signa, thereby achieving highly uniform beam spill under low-energy slow extraction conditions.

Speaker: Chuhao Li (Tsinghua University)

WEP4602_edited_version.pdf

16:00 A Beam Abort System for the Diamond-II Storage Ring

Due to the high energy density of the Diamond-II low-emittance electron beam, the risk of damage to storage ring components is considered high. A dedicated beam abort system is one way to safely dump the beam and protect the machine from damage. In this paper, we present the design of a beam abort system for the Diamond-II storage ring. The requirements of the key components will be described, including the kickers, beam dump and controller. Simulations of the effects of beam loss on the beam dump surface and collimator blades will be shown.

Speaker: Andrew Potter (Diamond Light Source)

WEP6138_edited_version.pdf

16:00 A Boundary Element And Fast Multiple Method For Electron Cloud Field Computation

Electron cloud build-up simulations rely on accurate self-consistent electric field computation to correctly model the secondary emission cascade. The PyECLOUD code solves this via a Particle-in-Cell (PIC) approach using the Shortley-Weller finite-difference (SW-FD) Poisson solver. This work presents a Boundary Element Method (BEM) formulation for the electrostatic space-charge field that discretizes only the chamber wall into panels and evaluates particle forces via direct Coulomb summation, entirely avoiding volumetric grids. The BEM solver is validated against the analytic image solution for a circular chamber (error $<0.2\%$) and cross-validated with the existing SW-FD solver on the LHC Arc-Dipole chamber, showing sub-percent agreement over the chamber interior. The BEM module is integrated into the PyECLOUD simulation pipeline as a plug-in field solver. Build-up simulations comparing BEM ($N=50$ and $N=200$ panels) with the baseline PIC solver (0.3~mm grid) produce consistent electron cloud line densities, confirming that the BEM formulation correctly captures the physics of the original solver. The BEM panels simultaneously provide a unified geometry for impact detection and secondary emission. The Fast Multipole Method is introduced to accelerate the intrinsic $\mathcal{O}(N^2)$ particle-particle Coulomb sum, and GPU acceleration is proposed as a path toward a standalone BEM-FMM code scalable to $>10^5$ particles.

Speaker: Siyuan Feng (Institute of High Energy Physics, Chinese Academy of Sciences)

WEP1607_edited_version.pdf

16:00 A Compatible Injection Scheme Design for the Super Tau-Charm Facility Collider Rings

The Super Tau-Charm Facility (STCF), a new-generation electron-positron collider proposed in China, is a major international scientific facility designed to operate in the center-of-mass energy range of 2–7 GeV, with luminosity at 4 GeV beyond 5x1034 cm-2s-1. It adopts third-generation collider design concepts, including ultra-small beam size, a large Piwinski angle, and the crab waist scheme. However, these features introduce challenges such as a limited dynamic aperture and a short beam lifetime, which significantly complicate beam injection. Two injection schemes are currently under investigation. The first is off-axis injection, which is technologically mature but requires a large horizontal dynamic aperture and is characterized by low injection efficiency and considerable beam loss. The second is swap-out injection, with stored bunches replaced by injected ones using ultra-fast kickers, improving injection efficiency and easing aperture constraints, but imposing stringent technical requirements and high costs on the injector system. To address these challenges, we propose an injection design compatible with both schemes, reserving upgrade potential from off-axis injection in Phase I to swap-out injection in Phase II.

Speaker: Linhao Zhang (University of Science and Technology of China)

WEP1624_edited_version.pdf

16:00 A comprehensive analytical model for RFQ beam dynamics

The Radiofrequency Quadrupole (RFQ) is the initial accelerating device in many modern linear accelerators (linacs), such as the European Spallation Source (ESS), where it accelerates protons from 75 keV to 3.6 MeV. Due to its complex geometry, RFQ beam dynamics are typically studied using finite element solvers, which, while accurate, are computationally intensive and unsuitable for online modeling. The widely used analytical "two-term" model, originally introduced by I. M. Kapchinsky and V. A. Teplyakov, provides a faster alternative but often suffers from inaccuracies, with errors in particle dynamics tracking reaching up to 20\%, particularly with high-intensity beams. This paper presents a comprehensive analytical model for the RFQ, detailing how to derive its coefficients based on boundary conditions induced by the RFQ geometry and demonstrating its application for particle transport simulations.

Speaker: Emanuele Laface (European Spallation Source)

WEP5084_edited_version.pdf

16:00 A configurable unsupervised anomaly detection service for the Advanced Light Source

Advanced Light Source (ALS) control systems operate with continuous streams of more than 200\,000 EPICS Process Variables~(PVs). While most alarms are handled by manually setting a threshold, we present a configurable service that scores live PV streams for anomalies in real time, providing a flexible fault discrimination tool for operators. The service applies a recurrent neural network to capture time-dependent correlations, trained on a given time range using unsupervised one-class loss that requires no labeled fault examples. Furthermore, we embed operationally-aware logic that suppresses false alerts during machine-off periods, ensuring detection quality without manual setpoint tuning per PV. We show the system in operation on live data from the ALS linac modulator capacitor voltage divider channels, and describe its architecture as a configurable, multi-instance service driven by a single JSON specification, enabling straightforward extension to additional PV groups as training data becomes available.

Speaker: Gianluca Martino (Lawrence Berkeley National Laboratory)

WEP6305_edited_version.pdf

16:00 A Low Cost Picoseconds Precision Timing and Synchronization Over A Kilometer

Large-scale accelerators, including colliders and accelerator-based light sources, require synchronization and time distribution over distances of several tens of kilometers. Precisions of femtoseconds have been demonstrated, but the systems used to reach such specifications are costly and difficult to integrate in a particle accelerator environment. Applications such as bunch-per-bunch position monitoring and Compton polarimetry require picosecond timing and precision and often meet tight integration requirements. This is particularly true for the latter, where a passively mode-lock laser must be integrated in the accelerator environment, with 10 to 100km scale. We propose to implement a system exploiting a White Rabbit protocol-based frequency generation system, the Idrogen. We demonstrate the proof-of-concept of synchronization of a pulsed laser with a few hundred megahertz repetition rate with picosecond jitter precision through a kilometer-long optical fiber. Drifts of a few picoseconds were observed, related to environmental changes. Prospects for improvements will be exposed.

Speaker: Alice Renaux (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

16:00 A low Energy Polarizer Ring for FCC-ee

Precise beam energy calibration is a basic requirement for FCC-ee operation at the Z and WW energies. The present baseline foresees to polarize low intensity bunches in the collider using asymmetric wigglers during about one hour prior to ramping up the intensity of bunches brought into collision for physics. Generation of polarized bunches at low energy in a dedicated ring is proposed as alternative to improve the efficiency of FCC-ee exploitation. First designs of such a dedicate polarizer ring and performance estimates will be presented.

Speaker: Christian Carli (European Organization for Nuclear Research)

16:00 A new analogue acquisition for the BPM of CERN PS

The bunch-by-bunch and turn-by-turn beam trajectory measurement system of the CERN PS accelerator has been in operation for several years. To ensure long-term reliability, the consolidation of the analogue acquisition chain is foreseen during the upcoming LS3 long shutdown including a new architecture with improved performance, which is currently under test in the PS accelerator for final validation. The key element is a custom-designed high impedance head amplifier, replacing the 50Ω amplifier used by the current system, with the advantage of improving, at the same time, bandwidth, dynamic range and noise level. Increased dynamic range opens the possibility of measuring longer acceleration periods without gain switching and better resolution. Increased bandwidth allows the measurement of more beam configuration, in particular with shorter bunch to bunch distance. However, improved performances come at the expense of placing active electronics close to the beamline, in locations with significant radiation exposure, therefore requiring radiation-tolerant electronics. An overview of the PS trajectory system is presented, with the focus on the design of the new analogue acquisition, along with the preliminary bench and beam measurement results.

Speaker: Michele Bozzolan (European Organization for Nuclear Research)

WEP6079_edited_version.pdf

16:00 A New Generation of Digital Low Level RF Control Systems

The SYES LLRF Systems of latest generation are Easy to Use, Efficient, Flexible and especially Affordable.
They can be fully software customisable to customer needs, in Fully Wide Band (30-900MHz) applications. The units feature Precise Frequency, Amplitude and Phase Control in continuous wave (CW) or Pulsed applications with real-time monitoring of RF signals.
The units assure full protection thanks to detection of Sparking and Reflected power(VSWR), with automatic power reduction or mute at customisable thresholds.
The complete control of the uniti is user friendly thanks to the local control GUI and its easy interface via Ethernet to any remote control system.

Speaker: Dr Michele Corvino (SYES)

16:00 A Novel Approach for Transverse Instability Detection in the CERN Proton Synchrotron

The CERN Proton Synchrotron faces increasingly demanding requirements from its user community, driven by the need for higher-intensity beams that push the machine to the limits of beam stability. Transverse instabilities, such as head-tail and transverse-mode-coupling instabilities, can arise at specific stages of the machine cycles, depending on the beam parameters. This work introduces a real-time, bunch-by-bunch transverse instability diagnostic system based on wide-band beam position monitor signals. Building on recent developments in longitudinal beam observation, the system extends the software layers to measure beam profiles in both longitudinal and transverse planes. A key feature is its ability to capture multiple time windows within a single cycle, offering a complete view of beam dynamics. Real-time analysis of the transverse beam envelope evolution is performed on the acquired data to detect and characterize performance-limiting phenomena, such as transverse instabilities. The system is fully integrated into operation, allowing simultaneous beam monitoring and optimization across multiple beam types.

Speaker: Amaury Beeckman (European Organization for Nuclear Research)

WEP6082_edited_version.pdf

16:00 A novel hybrid damping wiggler design for the Super Tau-Charm Facility

The Super Tau-Charm Facility (STCF), a next-generation electron-positron collider, requires ultra-low emittance and high luminosity, demanding strong synchrotron radiation damping. Due to limited ring circumference, conventional damping from bending magnets is insufficient, necessitating numerous damping wigglers. However, conventional electromagnetic wigglers face peak field limitations. To address this, a novel hybrid damping wiggler design is proposed, integrating auxiliary permanent magnets with the primary electromagnetic structure. This hybrid approach enhances excitation efficiency, achieving a peak magnetic field of nearly 2 T at a 40 mm gap. This innovation significantly reduces the required total length of damping wigglers, optimizing ring space while meeting stringent damping requirements for high-luminosity operations in the 2–7 GeV energy range.

Speaker: Hangzhou Li (University of Science and Technology of China)

16:00 A Python Framework for Integration of Measurements into the EPICS Control System

Many measurements in accelerator physics require dedicated scans of parameters, such as the main frequency of the RF system for chromaticity measurements or a variation of quadrupole strength for beta function measurements, etc. Such measurements cannot be performed by simply reading an instrument, but require a certain measurement procedure. These measurements are typically implemented as scripts, as they are often written by staff or students whose task is the measurement itself. For reusability and maintainability, however, an integration into the EPICS control system is favoured. This has multiple benefits such as the easy archiving of results in the central database or the integration of the measurements into the standard operator panels. To allow non expert staff and students to easily build measurements exposed via the EPICS control system, we built a framework in Python to implement such measurement routines as EPICS input-output-controllers (IOC). This framework allows the author of such measurements to focus on the measurement itself and still benefit from an EPICS integration without the need for extensive knowlege in EPICS IOC development.

Speaker: Patrick Schreiber (Karlsruhe Institute of Technology)

WEP6102_edited_version.pdf

16:00 A Realistic Proportional-Integral RF Feedback Model for Longitudinal Beam Dynamics Simulation in Electron Storage Rings

Modern fourth-generation storage ring light sources predominantly utilize digital I/Q-based proportional-integral (PI) feedback for their radio-frequency (rf) systems. This paper introduces a dedicated PI feedback model implemented in the STABLE tracking code to enable accurate longitudinal beam dynamics simulations. The model's key innovation lies in its treatment of the continuous transmitter current, which is discretized into electron-bunch-like charge pulses, while the cavity voltage is refreshed on an rf-cycle basis. This methodology offers a more physically accurate model of the beam-cavity-feedback coupling, providing a versatile tool for precise longitudinal beam dynamics studies in single- and multi-rf configurations.

Speaker: Tianlong He (University of Science and Technology of China)

16:00 A spacial Boris-like scheme for particle tracking in magnetostatic field: impleamentation and properties

Accurate and stable integration of charged-particle motion in complex magnetic fields is essential for beam-dynamics simulations in accelerators and beam lines.
For the Xsuite simulation framework we have recently developed a spatially discretized Boris-like algorithm that advances particle coordinates using the longitudinal position as the independent variable.
The scheme retains the symmetric kick–rotate–kick structure of the standard time-based Boris pusher, ensuring exact preservation of the total momentum magnitude and of the phase-space volume.
We derive its formal properties using operator-splitting and backward-error analysis, showing that it is second-order accurate, and that the symplectic error scales quadratically with the integration step.
Such properties are also verified by numerical tests on representative field distributions.

Speaker: Giovanni Iadarola (European Organization for Nuclear Research)

WEP5134_edited_version.pdf

16:00 A systematic analysis of cavity compensations in the JAEA-ADS linac utilizing the LightWin tool

The Japan Atomic Energy Agency (JAEA) is designing a 30-MW linear proton accelerator (linac) for the Accelerator-Driven Systems (ADS) to address the nuclear waste storage challenges. For Accelerator-Driven Systems (ADS) technology to be viable, it is necessary to minimize both the number of beam trips and their duration, thereby exceeding the performance of current linacs. JAEA is focused on implementing fast cavity compensation to minimize beam downtime caused by cavity failures. This approach makes rapid cavity retuning that enables a fast beam restoration with an acceptable quality. Beam dynamics studies for the JAEA-ADS linac have shown that it is possible to achieve a proper beam operation even when multiple cavity failures occur. As the JAEA-ADS linac consists of 293 superconducting cavities, it requires a rapid, automated, and systematic approach to determine the optimal readjustment settings for all cavities. To achieve this, we are utilizing the LightWin tool. This software has been developed for ADS linacs and was successfully applied to ADS MINERVA/MYRRHA linac. It has undergone testing and enhancements to improve SPIRAL2 operation. This study analyzes cavity compensation in the JAEA-ADS superconducting linac using the LightWin tool and compares the results with previous research.

Speaker: Jun Tamura (Japan Atomic Energy Agency)

WEP4621_edited_version.pdf

16:00 A Visible-Light Monitor for Transverse Beam Profile Diagnostics in the SLS Booster

A visible-light 2D imaging monitor was developed and commissioned in the Swiss Light Source (SLS) 2.0 booster ring to characterize transverse beam behavior during the energy ramp.
Installed downstream of a bending magnet, it extracts visible synchrotron radiation via an in-vacuum gold-coated mirror and uses a CMOS camera with motorized optics and filters.
The setup accommodates the evolving synchrotron spectrum, with the critical photon energy increasing from 0.2 eV at 100 MeV electron beam energy to approximately 3.9 keV at 2.7 GeV.
Long exposures, integrating over hundreds of turns matched to the roughly 1 µs revolution time, enabled measurements of adiabatic damping due to synchrotron radiation emission.
In addition, the system provides sufficient sensitivity to image single-bunch charges down to approximately 20 pC, while operating over a broad charge range up to 300 pC.
Using short exposures over only a few tens of turns enabled the observation of fast beam size evolution during emittance exchange driven by coupling resonance crossing, a technique first implemented
in an electron ring at the SLS*.
This high-speed acquisition confirmed the optimal extraction timing, corresponding to the minimum horizontal beam size.
The monitor provides non-invasive diagnostics for tracking beam stability and optimizing injection into the storage ring.

Speaker: Maria Paula Rey Barrera (Paul Scherrer Institute)

WEP6084_edited_version.pdf

16:00 Accelerating through partial snake resonances with betatron coupling spin resonance compensation

Partial snakes are used at the Brookhaven AGS to avoid strong vertical spin resonances during acceleration of polarized proton beam from 2.5 to 23 GeV. An unfortunate side effect is that these snakes excite numerous weak resonances associated with the horizontal betatron motion. We present experimental demonstration and operational experience of the compensation of these resonances during acceleration by exciting betatron coupling with a set of 15 pulsed skew quadrupoles.

Speaker: Vincent Schoefer (Brookhaven National Laboratory)

WEP4333_edited_version.pdf

16:00 Accelerator Design Educational Primer – Conceptualizing and Optimizing the Hybrid LHeC-like Electron-Ion Collider Design

The Electron-Ion Collider (EIC) Mission Need requires √s = 20–100 GeV (upgradable to 140 GeV) and luminosity 10³³–10³⁴ cm⁻² s⁻¹. The current ring-ring baseline achieves the full scope, including ~10³⁴ cm⁻² s⁻¹ across all energies. However, when the design is re-optimized for the lower boundary — accepting ~10³³ cm⁻² s⁻¹ and prioritizing cost — an alternative configuration emerges as more advantageous: a hybrid LHeC-like electron accelerator using multi-pass energy recovery linacs (ERL).
This solution reduces electron-beam power by roughly an order of magnitude, yielding nearly a factor of two reduction in total project cost compared with the present baseline while still satisfying the minimum physics requirements. The study performs parametric cost and performance modeling, augmented by AI-driven optimization, to explore this design space.
Serving primarily as an educational exercise for the next generation of accelerator physicists and engineers, the paper demonstrates modern design methods: rapid parametric scans, cost-driven optimization, and integration of AI tools. It examines technical feasibility, identifies critical R&D (high-current ERL operation, beam–beam effects, synchronization, etc.), and discusses how such re-optimization studies can be used to train designers in an era when artificial intelligence dramatically expands exploration of complex accelerator parameter spaces.

Speaker: Andrei Seryi (Old Dominion University)

WEV1301_edited_version.pdf

16:00 Accelerator optimization for large parameter numbers embedded in the native FAIR control system environment

The new accelerator complex, FAIR (the International Facility for Antiproton and Ion Research), will soon be commissioned to deliver ion beams using its injector and the GSI accelerator complex. In order to extend the operation of the GSI to include the FAIR and due to some ageing components, a new control system has been implemented.

The time- and resource-efficient setup of complex ion beams, a long-standing challenge, has been addressed with a Java-based application called DeviceAutomator. This application handles different optimization routines based on modern machine learning technology. Apart from selecting the most suitable algorithm, challenges arise from data quality and the number of independent parameters. However, since the application is fully integrated into the FAIR control system, all operators in the control room can access and freely configure it without the need for coding.

This contribution will describe the implementation and real-life testing of different algorithms: Bayesian, Genetic, and Random Walk. Using a long section of a low-energy ion transport beam line, it has been demonstrated that larger parameter spaces extending well beyond ten parameters present significant challenges for the Bayesian algorithm. However, the genetic optimization routine remains capable of identifying optimal values. It was also evident that a well-chosen optimization routine has the potential to make ion beam setup faster and less labor-intensive.

Speaker: Frank Herfurth (GSI Helmholtz Centre for Heavy Ion Research)

WEP6007_edited_version.pdf

16:00 Accelerator upgrades required for beam operation at Fermilab in the PIP-II/DUNE era

The Proton Improvement Plan - II (PIP-II) injector linac is an 800 MeV superconducting H- linac that will replace the existing 400 MeV injector to the accelerator complex at Fermilab. The higher energy, intensity and repetition rate require various upgrades to the existing accelerator complex consisting of the Booster, the Recycler Ring and the Main Injector, in order to be able to accept and accelerate beam from PIP-II. In this paper we discuss the various upgrades that are required and steps being taken to implement them.

Speaker: Srinivas Krishnagopal (Fermi National Accelerator Laboratory)

WEP4306_edited_version.pdf

16:00 Accumulator-to-Target Beam Transfer Line for ESSnuSB+

The ESSnuSB project aims to generate an intense neutrino beam and the associated muon flux, using a 5 MW high-power proton driver, requiring precise and reliable transport of the accumulated beam to the target station. To achieve this, a dedicated transfer line guides the extracted protons from the accumulator toward the neutrino beam direction while meeting strict geometric constraints.
The beam transfer line accommodates horizontal and vertical angular offsets of 16.8° and 2.29° using a compact sequence of horizontal and vertical dipoles, with quadrupoles ensuring controlled beam size and minimal losses. Simulations show that a lattice just over one hundred meters long successfully preserves beam quality and aligns the beam with the required neutrino direction. This guarantees stable, low-loss delivery of the beam to the downstream target system.

Speaker: Elian Bouquerel (Institut Pluridisciplinaire Hubert Curien)

WEP5007_edited_version.pdf

16:00 Adjoint Sensitivity Analysis for Design and Optimization

The design of accelerator lattices involves evaluating and optimizing Figures of Merit (FoMs) that characterize a beam’s properties. These properties—hence the FoMs—depend on the many parameters that describe a lattice, including the strengths, locations, and possible misalignments of focusing elements. Often what is required is the gradient of the FoM with respect to each of the parameters. For systems that require numerical simulation, a naïve computation of a gradient requires one simulation for the “base case”. plus one additional simulation for each parameter of interest—a daunting effort in the case of computationally demanding simulations with many parameters. Adjoint techniques allow one to extract gradient information from one base-case simulation plus an additional one or two carefully prepared simulations.* We demonstrate these techniques using the accelerator simulation code WARP, and we present our proof-of-concept results using several different FoMs as the basis for adjoint analyses of a simple beamline with multiple parameters.

Speaker: Dan Abell (University of Maryland, College Park)

16:00 Advanced beam coupling impedance modeling for LHC and HL-LHC applications

Accurate beam coupling impedance modeling is essential for predicting collective effects and ensuring stable high-intensity operation in the LHC and its High-Luminosity upgrade. Operational experience has shown that even small mechanical details can have a significant impact on the impedance of accelerator components, potentially leading to performance degradation or hardware failure. In addition, impedance sources are not static: beam-induced heating and the resulting mechanical stresses can drive gradual geometric changes, such as loss of electrical contact or deformation of shielding elements, thus modifying the impedance during operation. In this work, we present recent advancements in high-fidelity impedance modeling and demonstrate their relevance through representative case studies in the LHC. These examples show how improved modeling, combined with beam-based diagnostics, provides critical input for operational strategies and supports informed design and optimization of components in view of the challenging HL-LHC requirements.

Speaker: Carlo Zannini (European Organization for Nuclear Research)

WEP5101_edited_version.pdf

16:00 Advanced Linear and Nonlinear Optics Studies Using MAD-NG’s Parametric Differential Algebra.

Advanced linear and non-linear optics studies require accurate and efficient tools for high-order beam dynamics computations. MAD-NG provides a unique framework combining linear and nonlinear optics modelling, high-order parametric differential map computation through precise automatic differentiation, and Lie-algebraic operations central to nonlinear normal form analysis, all within a unified environment based on the Generalised Truncated Power Series Algebra (GTPSA). These capabilities enable accurate evaluation of optical functions, chromatic effects, and nonlinear Hamiltonian dynamics. MAD-NG embeds LuaJIT, a high-performance scripting engine, offering automated workflows, symbolic dependencies, and deferred evaluations for efficient lattice design and parametric optimisation. It has been successfully used to improve the LHC beam lifetime at injection (2023) and during collisions (2025) by minimisimg resonant driving terms. Applied to major projects such as the LHC, HL-LHC, and FCC-ee, MAD-NG demonstrates reliability, scalability, and accuracy for large-scale optics and sensitivity studies while providing a flexible, reproducible, and high-performance environment for modern accelerator modelling and advanced beam dynamics research.

Speaker: Laurent Deniau (European Organization for Nuclear Research)

WEP5074_edited_version.pdf

16:00 Advancing beam quality control in the CERN Proton Synchrotron

Over the past years, the beam quality delivered by the CERN Proton Synchrotron (PS) has significantly improved, driven by major upgrades to both the accelerator and its controls infrastructure. As a result, user requirements have become increasingly demanding, particularly for high-brightness beams for the LHC, but also for fixed-target beams. The PS, known for its versatility in supplying beams with widely varying characteristics to multiple facilities, must now meet tighter performance specifications while maintaining reliability and operational efficiency.
To address these challenges, a new beam quality monitoring framework has been developed, building on recent enhancements in data acquisition and online analysis capabilities. The system defines key beam quality metrics in real time, enabling early detection of drifts, root-cause fault analysis, and provides the foundation for automated corrections and machine learning–based optimisation. Complementing this analytical layer, a dedicated graphical interface provides operators with live observability of key parameters and short-term trends, facilitating rapid decision-making in the control room.
This new approach represents a step change in the way beam quality is monitored and maintained in the PS, from reactive diagnostics to proactive control, supporting both operational stability and the increasingly stringent demands of CERN’s experimental program

Speaker: Marcel Coly (European Organization for Nuclear Research)

WEP6081_edited_version.pdf

16:00 AI-driven knowledge and logs integration system at ELI Beamlines

The key to successful AI-Chatbot implementation is integrating multiple data sources across the scientific facility. At ELI Beamlines, the system will aggregate heterogeneous operational data sources, including control system logs and archived telemetry, alarm system records, digital logbook entries, and other knowledge bases. This integrated repository forms the foundation for an AI chatbot that provides real-time, context-aware support to control room operators.
The chatbot leverages this unified knowledge base to assist in troubleshooting technical issues, answer facility-specific queries, and automatically generate operations log reports. This approach aims to reduce operator cognitive load and improve efficiency by combining multiple knowledge streams into a single, accessible interface. We outline the system architecture, the data integration strategy, and how this AI-powered tool supports daily operational workflows and knowledge management at ELI Beamlines.

Speaker: Wojciech Soroka (S2Innovation Sp z o. o. [Ltd.])

16:00 An automated production test suite for capacitive alignment sensor conditioning electronics

The High Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN requires exceptional alignment accuracy of accelerator components to reach the luminosity targets and to ensure reliable beam operation. This accuracy is achieved with the help of the Full Remote Alignment System (FRAS), which employs a capacitive Wire Positioning System (WPS) to monitor the position of magnets, RF cavities, and other accelerator components relative to a stretched, conductive, reference wire. Each WPS sensor measures distance offsets with respect to this reference wire with sub-micron-level resolution. The sensors are connected via dedicated cables to specially designed WPS conditioning electronics for signal processing and data acquisition. These modules operate as application specific cards within CERN’s Distributed Input/Output Tier (DI/OT), a standardized framework designed for modular electronics operating in radiation-exposed environments.

To support the large-scale production and verification of over 400 WPS conditioning modules, an automated Production Test Suite (PTS) has been developed. The PTS streamlines firmware programming, automates test execution and ensures full traceability through integration with CERN's Enterprise Asset Management (EAM) platform and the Engineering Data Management Service (EDMS). This paper presents the design and validation of the PTS for WPS conditioner electronics, focusing on hardware–software integration and its role to enable reliable production testing for the HL-LHC.

Speaker: Roberto Fernandez Bautista (European Organization for Nuclear Research)

WEP6120_edited_version.pdf

16:00 An Updated Assessment of the Electron Cloud Effects in the Damping Ring of the FCC-ee Injector Complex

The new FCC-ee injector complex design, as outlined in the feasibility report, consists of an electron source, two separate linacs for electron and positron beams to accelerate beams up to 2.86 GeV, a positron production target, a damping ring at 2.86 GeV energy for emittance cooling, a bunch compressor, a high energy linac to accelerate the beam up to 20 GeV, and an energy compressor.

The primary function of the damping ring design is to accept the 2.86 GeV positron and electron beams coming from the electron linacs, reduce their beam emittances, and deliver the required beam quality for injection into the subsequent high-energy linac. It is essential for decreasing the emittance of the incoming positron beam from 2.36x10^-6 m.rad to about 1.8x10^-9 m.rad. Among the collective effects that may limit the performance of the positron rings, the electron cloud (e-cloud) effect remains one of the most significant challenges. This paper presents the results of updated studies of the e-cloud impact on various damping ring design options for the FCC-ee, including the latest version.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

WEP1014_edited_version.pdf

16:00 An updated physical design of the super Tau Charm Facility collider rings

The Super Tau-Charm Facility (STCF), proposed by the University of Science and Technology of China, is a next-generation electron-positron collider designed to achieve a luminosity exceeding 5×10^34 cm^-2s^-1, approximately two orders of magnitude greater than that of BEPCII. Large Piwinski angle with the crab waist collision scheme is applied. However, the extremely small βy* (<1 mm) generates very large nature chromaticity. Local chromaticity corrections for both horizontal and vertical planes have been proposed. Touschek lifetime is very challenging due to its low-energy, low-emittance, and high-current. A two-folded lattice has been proposed for the collider rings, with the iterations of version 5. Nonlinear optimization has been carried out with Multi-Objective Genetic Algorithm (MOGA) to maximise the dynamic aperture and momentum acceptance, considering fringe fields and misalignment errors. This paper introduces the updated physical design of the STCF collider rings.

Speaker: Dr Ye Zou (University of Science and Technology of China)

WEP1603_edited_version.pdf

16:00 ANALOG DOWN-CONVERSION AND DIGITAL READOUT SYSTEM FOR A CAVITY BPM BEAM TESTED AT ATF

A complete analog readout system designed to extract reference and position signals from a single cavity Beam Position Monitor (cBPM) has been developed for a proto type from CEA Saclay. The complete system underwent beam testing at the Accelerator Test Facility (ATF). The monitor operates with a dipole mode centered at 1.725 GHz, requiring translation to lower frequencies for digitization and subsequent signal processing via a digital-down-conversion (DDC) algorithm. Throughout beam campaigns in May, June, and December 2025, various synchronized local oscil lator (LO) configurations and down-conversion architectures were evaluated. The final optimized systems achieved intermediate fre quencies (IF) of 417 MHz, 297 MHz, and 60 MHz. Through iterative enhancements in synchronization, filtering, and hardware integration, a peak vertical resolution of 2.81 µm was demonstrated.

Speaker: Juan Carlos Fernández Ortega (Instituto de Física Corpuscular)

16:00 Analysis and Compensation of Crosstalk Effects for the Diamond-II Bending Magnets

The close proximity of the magnets on the Diamond-II girders leads to significant crosstalk effects. This is of particular concern for the dipole component of the bending magnets, as the truncation of the fringe fields reduces the integrated strength and distorts the closed orbit. Tuning of the field strength and accurate alignment of the magnets is required to recover the target bend angles. A similar effect is seen on the quadrupole fields, and adjustment of the nominal gradients is required to restore the design optics. In this paper we present an overview of the modelling methods and latest results from these studies.

Speaker: Ian Martin (Diamond Light Source)

WEP5056_edited_version.pdf

16:00 Analytical Estimates of Beam Intensity Limitations in the EIC Beam Accumulator Ring

We have done analytical estimates of beam intensity limitations in the Beam Accumulator Ring (BAR), a part of the Electron-Ion Collider injector complex under development at Brookhaven National Laboratory. Analytical models of longitudinal and transverse collective eJects are developed using a broadband impedance model calibrated with the beam-based measurement results from NSLS VUV. The study evaluates the impact of resistive-wall and geometric impedances, assessing microwave and transverse mode coupling instabilities, bunch lengthening, and beam-induced heating.

Speaker: Victor Smaluk (Brookhaven National Laboratory)

WEP1326_edited_version.pdf

16:00 Analytical solutions for particle tracking in planar crystal channelling

Planar particle channelling describes the motion of high-
energy particles trapped in the potential well formed by
crystal lattice planes, allowing their trajectories to be de-
flected in a controlled manner. Within the Molière approx-
imation, which incorporates atomic screening and thermal
vibrations, this motion is typically either approximated by
a harmonic potential or evaluated numerically. Here, we
propose a simplified Molière model that yields closed-form
analytical solutions expressed through Jacobi elliptic func-
tions. To extend the treatment to bent crystals, symplectic
integrators are applied to the equations of motion, ensuring
accuracy and long-term stability through symplecticity. This
semi-analytical approach to evaluate bent channelling has
been benchmarked against existing numerical methods, and
the optimal configuration has been integrated into Xsuite’s
Xcoll package.

Speaker: Silke Van der Schueren (European Organization for Nuclear Research)

WEP5086_edited_version.pdf

16:00 Anomaly Detection and Denoising of Non-Gaussian Beams using 2D Image Reconstruction Techniques based on Deep Learning

Automatic image reconstruction tools are essential in fields such as physics, astronomy, and biology. In particle accelerators like CERN’s LHC, they are particularly important for evaluating beam quality through beam distribution measurement as position, profile, and emittance. Traditional analysis tools no longer meet the accuracy and efficiency demands of future facilities. We developed a new AI/DL-based digital tool for 2D transverse phase-space distributions and scanner image denoising aimed at improving the accuracy of RMS emittance measurements. Our focus was to enhance beam halo characterization, ultimately contributing to reduce transport losses, and enabling more sustainable accelerator operations.
Challenges are related to noisy experimental data, lack of ground-truth reference images, noise model, and limited training datasets. Our unsupervised deep convolutional neural network (DCNN) can denoise a single image using only itself as input thus greatly improving the accuracy of beam surface area estimation and hence the RMS emittance measurement.

Speaker: Francis Osswald (Institut Pluridisciplinaire Hubert Curien)

WEP6003_edited_version.pdf

16:00 Applications of High-Dimensional Time-Delayed Embedding for Time Series Complexity Estimation

Turn-by-turn (TbT) data are readily available in modern circular accelerators and are widely used to infer machine parameters in both simulations and experiments. In the latter case, TbT data record transverse beam-centroid positions from beam position monitors (BPMs) and therefore include measurement noise and decoherence. We construct high-dimensional time-delay embedding of TbT time series, yielding matrix representations of the signals. Since the signals considered are typically near-quasiperiodic with harmonics of the fundamental betatron frequencies, the embedded matrices are expected to be low-rank. We leverage this rank structure to define a complexity indicator on singular-value spectra, which are related to the underlying quasiperiodic structure of the TbT signals.The proposed framework provides a simple, data-driven diagnostic for complexity estimation directly from TbT records and is compatible with experimental datasets.

Speaker: Ivan Morozov (Elettra-Sincrotrone Trieste S.C.p.A.)

WEP5027_edited_version.pdf

16:00 APPLYING MACHINE LEARNING TO LONGITUDINAL PHASE SPACE RECONSTRUCTION IN THE LANSCE CCL

Traditional phase scans at LANSCE are useful for tuning longitudinal capture but provide only indirect information about the bunch distribution. This work extends a deep neural network-based reconstruction method to the first two modules of the side-coupled cavity linac. Simulated two-dimensional phase scans were generated with HPSim by varying the RF phases of Modules 5 and 6 and recording the transmitted current after the absorber/collector diagnostic. A retrained network reconstructed correlated Gaussian longitudinal phase space distributions from these scans, recovering their approximate size, orientation, and centroid. These results support further development using realistic distributions and measured CCL phase scans.

Speaker: Martin Kay (Los Alamos National Laboratory)

WEP4315_edited_version.pdf

16:00 Assessment of fabrication and assembly tolerances in an IH-DTL cavity through electromagnetic and beam dynamics Simulations

This work presents a comprehensive study of manufacturing and assembly errors in a 750 MHz Interdigital H-mode Drift Tube Linac (IH-DTL) cavity designed for a compact and efficient ion beam inyector. Operating at such a high RF frequency significantly reduces the cavity dimensions but it also increases the sensitivity to geometric imperfections, posing a substantial technological challenge for manufacturing and assembly. In this study, realistic machining deviations — including drift-tube misalignments, stem eccentricity, profile machining errors, and end-cell distortions — are introduced within typical fabrication tolerances. Three-dimensional electromagnetic simulations quantify the resulting perturbations in the resonant frequency, accelerating fields, and power efficiency. First, the most critical geometric perturbations were identified by means of a single cavity cell model. Then, those errors were implemented in a complete cavity, applied to all cells. The resulting field maps were subsequently imported into multi-particle beam dynamics simulations to evaluate their impact on beam quality, transmission, and emittance growth. The study provides experimental tolerance thresholds and offers guidance for cavity fabrication, quality control, and commissioning strategies for IH-DTL structures.

Speaker: Pedro Calvo (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas)

WEP5083_edited_version.pdf

16:00 Asset Management Workflows for cSTART using Snipe-IT

For the cSTART project the Institute for Beam Physics and Technology (IBPT) at the Karlsruhe Institute of Technology (KIT) introduced with Snipe-IT a new system to manage all accelerator related components. As the new components arrive, one of the first step is entering them into the asset database, which creates a unique identifier. This identifier is then also used during the quality inspection process as the main reference. The asset-to-asset associations possible with Snipe-IT provide a simple and efficient method for structuring the components in cabinets and along the storage ring. The flexible custom fields allow to track references to other data sources, which provide the more technical information such as CAD drawings, cable routing and device documentation. In addition, it also allows to track component specific information. This contribution describes the established workflows, status and lessons learned using a generic IT asset management system for accelerator component management.

Speaker: Julian Gethmann (Karlsruhe Institute of Technology)

WEP6130_edited_version.pdf

16:00 Autoencoder Architectures For Beam Anomaly Detection And Statistical Distribution Characterization

In accelerator facilities, the control and assessment of a high-quality beam delivery require capable monitoring systems, including both hardware and software components. In most accelerator beamlines, precise measurements and reliable beam delivery are critical factors in their operation. At the CERN IRRAD facility, the transverse beam profile carries the essential information about the beam properties of interest for materials and component irradiation. Precise measurements and reliable beam delivery are critical factors in its operation.
Building upon the existing IRRAD-BPM (Beam Profile Monitor) instrument at CERN, we explore the possibilities of employing Machine Learning techniques, with special focus on Autoencoder (AE) architectures. Dealing with a critical system that involves high-energy protons and extreme radiation conditions, we developed an AE-based anomaly-detection system. Its architecture, based on multiple parameters, is a result of hyperparameter optimisation aiming for the highest separation of anomalous samples. Additionally, to mitigate the existing limited BPM coverage that cannot capture the full extent of the beam tails, we perform a measurement-space statistical inference using this AE architecture. Moreover, by using a Multi-Wire Proportional Chamber (MWPC) device also present on the IRRAD beamline, we improve the beam profile modelling within a data fusion-like approach.

Speaker: Jaroslaw Szumega (European Organization for Nuclear Research)

WEP6022_edited_version.pdf

16:00 Automated RF Conditioning on CLARA

In this paper we present the design and deployment of the software tools used for the automated parallel conditioning of 7 RF cavities on CLARA (Compact Linear Accelerator for Research Applications). The software tools consist of 4 distributed tools with the following responsibilities: Control, Acquisition, Visualisation, and Communication. In combination, these tools enabled the round-the-clock conditioning of all RF cavities with minimal operator intervention, achieving operating parameters for beam commissioning activities.

Speaker: Bradley Wilson (ASTeC, STFC Daresbury Laboratory)

WEP6171_edited_version.pdf

16:00 Automated software workflow for accelerator control systems using containerization

Managing large number of Input / Output Controllers (IOCs) and Graphical User Interfaces (GUIs) in a multi-network facility is challenging, since there are several resources of failures large scientific facilities may face in their life cycle, including hardware failures in servers and networks, operating system issues like high CPU and memory usage, and application issues such as crashes and memory leaks. A new software workflow is developed and released at SESAME that solves the preceding issues. The workflow includes containerizing software in independent units using Docker, orchestrating those units from a central manager using Kubernetes, managing installing, releasing, and rolling back of the deployments using Helm, and automating the process through a well-defined pipeline using continuous deployment using Jenkins. This workflow is immune to human error as every step is fully automated. Also, this workflow reduced development and deployment time significantly and enhanced IOCs availability. Currently, SESAME’s accelerator control system is almost fully managed by the described workflow, while beamlines integration is in progress.

Speaker: Amro Aljadaa (Synchrotron-Light for Experimental Science and Applications in the Middle East)

WEP6115_edited_version.pdf

16:00 AWAKE Laser Synchronisation and Optical Timing Distribution Network

The Advanced Wakefield Experiment (AWAKE) at CERN demands state-of-the-art timing and synchronisation performance. Upgrades due for completion 2029 require sub-50 fs laser synchronisation from its distributed laser systems to achieve experiment baselines. Accordingly, a time-of-flight stabilised all-optical timing distribution network in development with Lancaster University aims to establish a timing coherence of tens of femtoseconds between sub-systems separated by 100 m. This contribution outlines system architecture, stabilisation strategy and progress to date.

Speaker: Joshua Gregory (Lancaster University)

16:00 Balancing Stability and Ambition: LHC Availability in Run 3

Run 3 represents the final operational phase of the LHC before the transition to the High-Luminosity (HL) LHC era. It covers the operational years 2022 to 2026 and ends just before Long Shutdown 3, starting in July 2026. This period is defined by the successful restart of beam operation following the maintenance and upgrades during Long Shutdown 2, the establishment of a stable operational scheme enabling record-breaking integrated luminosities, and the exploration of performance limits in preparation for HL-LHC. This has all been achieved with infrastructure and equipment soon approaching two decades since first commissioning.

Run 3 availability was closely monitored using CERN’s Accelerator Fault Tracking tool, which records fault source, duration, and cross-system impacts. The analysis presented here extracts lessons for HL-LHC from these fault statistics. Machine unavailability is dominated by long-duration faults arising from latent weaknesses, often introduced by recent upgrades and exposed when performance is pushed to its limits. While individual systems require targeted mitigation, there is little evidence of accelerator-wide aging. Radiation-induced faults show a strong impact, demanding specific attention for HL operation. These insights support future strategies for efficient machine exploitation.

Speaker: Lukas Felsberger (European Organization for Nuclear Research)

16:00 Bayesian Optimization of Longitudinal Phase Space in the MAX IV Linac

Reaching design performance in modern particle accelerators is a challenge involving many tasks which are time-consuming and difficult to perform. It is always an advantage to be able to simplify high-level operational tasks and measurements through the assistance of optimization techniques. In this work we applied Bayesian optimization via the XOpt framework with the aim to simplify and enhance the operations in the MAX IV linac. The focus of this work has been longitudinal phase-space optimization using signals from a transverse deflector system. Further, a new approach in the optimization of longitudinal phase-space parameters with the use of virtual diagnostics has been developed and implemented.

Speaker: Johan Lundquist (Lund University)

WEP6015_edited_version.pdf

16:00 Beam acceleration with multi-harmonic excitation of the main magnets in a rapid-cycling synchrotron

In a rapid cycling synchrotron, sinusoidal excitation using an LC resonant circuit is commonly used as the current pattern for the main magnets. In this case, dB/dt reaches its maximum value at the 1/4 cycle period, and the time variation of dB/dt is important in determining the required RF acceleration voltage. Multi-harmonic excitation can be considered as a method to reduce the time variation of the bending magnetic field. Mathematically, a 12.5% of 2ndharmonic can suppress dB/dt to 75%, i.e., B(t) = Bo + B1(cos(ωt)+0.125sin(2ωt)), which also leads to suppression of RF peak voltage. In this study, we compare the advantages of sinusoidal excitation and harmonic excitation using the J-PARC RCS as an example.

Speaker: Masahito Yoshii (High Energy Accelerator Research Organization)

16:00 Beam Adjustment based on the Gradient Boosting Decision Tree Analysis in the KEK Electron/Positron Injector LINAC

KEK-LINAC is an electron/positron linear accelerator used as the injector for the synchrotron radiation facilities (PF ring and PF-AR) and SuperKEKB. The stable operation of experiments at these facilities requires reliable beam supply from the LINAC. We have newly introduced an analytical method based on gradient boosting decision tree (GBDT) to further enhance our beam adjustment capability. GBDT is one of machine learning methods and has been used as an exceptionally effective model for tabular data. The GBDT analysis handling hundreds of LINAC operating parameters predicted accurately beam’s charge and position in the LINAC. Furthermore, by performing SHAP analysis, we have identified key parameters for the beam adjustment and correlations between the parameters. Furthermore, it was found that a model trained by the analyses can be utilized as a surrogate model for fast simulation of beam behavior in the LINAC. The results of beam adjustment with the GBDT analyses will be shown in this presentation.

Speaker: Dr Taichi Sakai (High Energy Accelerator Research Organization)

WEP1615_edited_version.pdf

16:00 Beam based optimization of the ESR linear optics model

At GSI Darmstadt, the ESR storage ring is a fundamental device for atomic physics experiments. The operation of this storage ring requires precise control of the machine optics. However, the ESR has suffered from imprecise optics control, which yielded a mismatch of about $\sim0.1$ in the tune predicted by the MAD-X model.

In this work, we present a beam-based method to reduce these tune deviations by improving the linear optics model of the ESR. Using Differential Evolution (DE), a population-based derivative-free optimizer, we determine correction factors for the quadrupole families by minimizing the discrepancy between simulated and measured betatron tunes. The optimized lattice reduces the tune discrepancy of $\Delta Q$ to the level of $0.01$. The agreement in the beta functions and dispersion is preserved or slightly improved.

The resulting optics model provides a significantly more accurate representation of the ESR and offers a reliable basis for improved machine operation, future beam-based studies, and further nonlinear or global optics optimization.

Speakers: Aaron Heinz (Goethe University Frankfurt), Areso Sherjan (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Beam dynamics optimization of the high energy linac of the FCCee injector

The FCC-ee injector complex is designed to deliver tunable, high-charge electron and positron bunches for injection into the collider over a center-of-mass energy range of 90--365~GeV. A key element is the high-energy (HE) linac, which accelerates the beam from about 3 to 20~GeV before injection into the booster. In this work, we present beam-dynamics studies aimed at minimizing emittance growth and improving transverse stability along the HE linac. Different lattice configurations, phase advances, and RF layouts were investigated to identify an optimized design. The selected configuration satisfies the present performance requirements for efficient booster injection and supports the operational goals of the FCC-ee injector complex.

Speaker: Simona Bettoni (Paul Scherrer Institute)

WEP5054_edited_version.pdf

16:00 Beam Dynamics Simulations for the Design of a Heavy-Ion Storage Ring Equipped with a Beam-Recycling System

Research on short-lived unstable nuclei (radioactive isotopes, RIs) has progressed rapidly in recent years, driven by advances in accelerator technology and in the production and separation of RIs. Consequently, nuclear reaction experiments using rare RIs far from the valley of stability have attracted increasing attention. To improve the measurement accuracy of nuclear reactions involving such rare RI beams, we propose a beam-recycling technique. In this technique, RI beams are accumulated in a heavy-ion storage ring equipped with an internal active target until a nuclear reaction occurs. The energy loss, energy straggling, and transverse angular straggling experienced by the accumulated RI beams as they pass through the active target are corrected turn by turn and particle by particle. These corrections are optimized through feedback from the internal active target, maintaining high beam quality throughout the accumulation process.
We estimated the required performance of the beam-recycling components—including the internal active target, feedback systems, and beam-correction systems—through beam dynamics simulations in a heavy-ion storage ring implementing this concept. This presentation introduces the conceptual design of the beam-recycling ring and reports the simulation results.

Speaker: Ryo Ogawara (RIKEN Nishina Center)

16:00 Beam Dynamics Study for a Modified Low-Emittance RF Photogun

High-brightness and low-emittance beams generated in RF-gun–based accelerators are essential for a number of applications, such as free-electron lasers (FELs), ultrafast electron Diffraction facilities and THz radiation sources. In these accelerators, the final beam characteristics are determined both, by the properties of the electron gun and by the influence of the electromagnetic system along the beamline. To meet the requirements imposed on beam characteristics, it is essential to identify the optimal parameters of the RF gun and the magnetic system. In this paper, beam dynamics studies of a modified RF photogun for the AREAL and REGAE accelerators are presented, with emphasis on transverse emittance compensation. Simulations were conducted by adjusting the parameters of the focusing and RF systems to identify the optimal configuration of the modified RF gun.

Speaker: Dr Armen Grigoryan (Center for the Advancement of Natural Discoveries using Light Emission)

WEP5120_edited_version.pdf

16:00 Beam instrumentation for AWAKE from Run 2b to Run 2c

The AWAKE experiment at CERN is a proof-of-principle facility that uses proton-driven plasma wakefields to accelerate externally injected electrons. Since initial operations in 2016, multiple experimental phases have been completed, with the most recent being Run 2b. Beam diagnostics played a crucial role during this phase, enabling reliable operation and characterisation of the particle beams. The next phase, Run 2c, planned to begin in 2029, will introduce a second electron beamline delivering 150 MeV, 200 fs (RMS)-long electron bunches together with a second plasma. The increased experimental scale and the new measurement requirements impose new demands on beam instrumentation, requiring upgrades to existing systems and the development of new, specialised diagnostics. This contribution presents a non-exhaustive overview of the diagnostic systems used during Run 2b, describes the planned upgrades and developments for Run 2c, and discusses the associated integration challenges.

Speaker: Collette Pakuza (European Organization for Nuclear Research)

WEP6078_edited_version.pdf

16:00 Beam loss dynamics from spurious CLIQ discharges in HL-LHC inner triplet magnets

The High-Luminosity Large Hadron Collider (HL-LHC) will increase the nominal LHC integrated luminosity by a factor of 10 and operate with proton beams storing up to 700 MJ of energy per beam. In this upgraded machine, a new quench protection system, the Coupling-Loss Induced Quench (CLIQ) system, will be installed in combination with conventional quench heaters to protect the Nb3Sn inner triplet superconducting magnets. A spurious CLIQ discharge with circulating beams represents the most critical beam-loss-related failure scenario in the HL-LHC era due to the rapid electromagnetic field perturbations it induces.
Simulations combining dynamic electromagnetic field maps from a spurious CLIQ discharge with Xsuite beam tracking show that the entire beam can be lost within 4 ms, with critical loss levels, defined as losses sufficient to pose a risk of damage to accelerator components, reached within only a few turns. Both double-Gaussian and q-Gaussian halo profiles are studied, revealing significant sensitivity of beam losses to the tail population distribution. The influence of machine optics is also examined, showing that the baseline round optics provide sufficient safety margin, whereas for the flat optics option this becomes significantly more critical.

Speaker: Jan Uythoven (European Organization for Nuclear Research)

WEP1003_edited_version.pdf

16:00 Beam Loss Study for the L-shaped Corrugated Structure at European XFEL

The European XFEL is a free-electron laser facility based on a superconducting linac with high bunch repetition rates of up to 4.5 MHz. An L-shaped corrugated structure has been installed upstream of the SASE1 undulator for fresh-slice operation and ultrashort-pulse generation. As the electron beam passes through the structure, strong longitudinal and transverse wakefields are excited which induce a correlated energy chirp and transverse kicks along the bunch. Since the gap between the corrugated structure and the beam is typically less than 1 mm, any beam misalignment or tail expansion may result in particles hitting the corrugated surfaces. For the L-shaped geometry this may occur on both the horizontal and vertical surfaces. Such interactions lead to energy deposition and secondary radiation that may cause damage to the downstream undulators. For this reason, studies have been carried out using BDSIM to simulate the losses caused by the L-shaped corrugated structure. Simulation results have been compared with in-situ radiation measurements using an autonomous robot.

Speaker: Jiacheng Wu (Deutsches Elektronen-Synchrotron DESY)

WEP6123_edited_version.pdf

16:00 Beam Misalignment and Current Loss in the Karaj-C30 Cyclotron: Diagnostics and IBSimu Analysis

The 30 MeV Karaj-C30 cyclotron, developed for medical and industrial radioisotope production, accelerates H⁻ ions to 15–30 MeV and D⁻ ions below 15 MeV using a carbon stripper foil for extraction. The system features a filament-based negative hydrogen multicusp ion source providing 1–2 mA, an injection line with optical elements, a two-sector electromagnet, and an RF resonator. Beam profiles measured 30 cm upstream of the stripper magnet using a Mylar foil revealed a significant horizontal shift and beam loss on the injection-line optics. IBSimu simulations of the extraction system reproduced this deflection and indicated that erosion of the ground electrode created a radial electric field responsible for the observed misalignment. Replacing the damaged electrode restored the beam trajectory and recovered the extracted current to 80 μA, in agreement with simulation predictions. Despite the improved alignment, the measured profiles still show signs of non-optimal extraction optics and a perveance mismatch. Future work will focus on redesigning the extraction system to achieve higher transported currents for isotope production.

Speaker: Keyvan Tabaei (University of Isfahan)

16:00 Beam positions monitors for PERLE injector

PERLE is an Energy-Recovery Linac (ERL) to be constructed at IJCLab in Orsay. It will be the First ever multi-turn ERL with superconducting RF (SRF) acceleration, and the first ERL with the ambition to reach 5MW beam operation. Diagnostics are a key element for PERLE operation and among diagnostics, Beam position monitors (BPMs) cover a wide range of applications. We report BPM goals for a proper operation of PERLE, it also details the design of BPM detectors and eludes the steps for their realization. it finally discusses the design of BPM electronics to match the presence of multiple beams which need to be individually diagnosed and controlled.

Speaker: Dr Mohammed Ben Abdillah (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

WEP6036_edited_version.pdf

16:00 Beam trapping in stable resonant islands of the longitudinal phase space by RF phase modulation in electron rings

An RF phase modulation whose frequency is set close to a resonant condition with the synchrotron tune can be used to form resonance islands in the longitudinal phase space. A slow variation of the modulation amplitude and frequency can be performed to trap particles inside the island structure and to realise adiabatic transport, according to adiabatic theory for Hamiltonian systems. However, when dealing with electron beams, energy damping and quantum excitation effects cannot be neglected, and the adiabatic trapping into resonance can be described as an isothermal transformation of an ensemble of particles that evolves according to an adiabatically modulated Hamiltonian. In this study, we establish the theoretical framework for describing longitudinal motion under slow modulation of the RF phase using stochastic dynamical system theory. We also present numerical simulations with parameters of realistic lepton rings to characterise beam splitting between the core region and a $1:1$ resonant island. Special attention has been given to the thermal properties of the two beamlets, which define their equilibrium emittances and their lifetimes.

Speaker: Massimo Giovannozzi (European Organization for Nuclear Research)

WEP5067_edited_version.pdf

16:00 Beam tuning studies for the RAON linear accelerator

Various studies have been conducted to tune the linac. The RF set-points of the superconducting linac is determined with phase scan technique with BPMs. With the BPM calibration, the beam energy is quite accurately determined. We check the beam energy from phase scan with dipole scan method. Transverse beam matching between sections of the linac has been tried successfully. Tomography reconstruction of the beam phase space is also tried from wire-scanner profile measurements and compared with the Allison scanner emittance measurement.

Speaker: Dong-O Jeon (Institute for Basic Science)

WEP4625_edited_version.pdf

16:00 Beam-based Instability and Bunch-by-Bunch Feedback Characterization at SOLEIL

In the context of the ongoing SOLEIL II upgrade, a measurement campaign was conducted to characterise and understand the behaviour of single- and coupled-bunch instabilities, and the performance of the transverse bunch-by-bunch feedback system at the present SOLEIL storage ring. This paper presents the key results of beam current thresholds measurements; growth-damp measurements with resistive feedback, drive-damp measurements with resistive feedback, tune shift measurements with reactive type of feedback. The results constitute a snapshot of instabilities and bunch-by-bunch feedback performance at SOLEIL. Our results guide in designing the bunch-by-bunch feedback system for SOLEIL II.

Speaker: Vadim Gubaidulin (Synchrotron soleil)

WEP5106_edited_version.pdf

16:00 Beam-Based misalignment studies for physical realignment options at cSTART

One of the objectives of the cSTART project (compact STorage ring for Accelerator Research and Technology) is the injection and storage of ultra‑short electron bunches into a storage ring. With a storage time of 100 ms, resulting from the 10 Hz repetition frequency, and a beam energy between 40 and 90 MeV, the beam will not reach equilibrium conditions. KIT plans injection from two sources, a laser‑plasma accelerator and the linac-based FLUTE accelerator. Precise magnet positioning will be important for keeping the intended ultra‑short bunch lengths. The initial laser‑tracker‑based alignments may not be sufficient to meet the requirements for such bunch lengths, resulting in the need for additional realignment options.
This contribution presents the first studies of methods for beam-based misalignement measurements at cSTART targeted at the possibility to physically realign the magnets for improved alignment accuracy.

Speaker: Patrick Schreiber (Karlsruhe Institute of Technology)

WEP5019_edited_version.pdf

16:00 Beam-beam Effects in Future Recycling Linear e+e- Colliders

Recycling collided particles and their energy opens path to very high luminosity O(E36) e+e- linear colliders aka ReLiC [1]. The main challenges of such concept are in computing low energy tail caused by beamstrahlung and limiting emittance blow-out during collisions. Beamstrahlung control requires colliding super-flat beams with size ratio exceeding 1,000. We present detailed simulations of collision effects as function of the c.m. energy and discuss requirements for damping ring in such collider.

Speaker: Vladimir Litvinenko (Stony Brook University)

16:00 Beam-charge diagnostics in laser-plasma accelerators with diamond detectors

Accurate measurement of shot-to-shot fluctuations in electron beams produced by laser-plasma accelerators (LPAs) is important for their development. Reliable monitoring of beam reproducibility and stability is crucial for accelerator operation. However, the high peak current and electromagnetic pulse environment make beam diagnostics challenging. In this work, preliminary results of bunch charge measurements using a diamond detector in an LPA environment are presented. A dedicated sCVD diamond detector was installed at the Lund High-Power Laser Facility. The average electron bunch charge was measured via a transverse beam scan. The measurement results are discussed, and an outlook on the development of diamond-based beam diagnostics and dosimetric applications for LPA facilities will be given.

Speaker: Divya Divya (TU Wien)

WEP6029_edited_version.pdf

16:00 Beam-induced heating Analysis and Optimization of the Stripline Kicker for the STCF

The Super Tau-Charm Facility (STCF) is a tau–charm electron-positron collider currently under design, with a projected single-bunch charge of up to 8 nC and an average beam current as high as 2 A. On-axis swapping injection is one of the feasible injection schemes; however, the high-current beam can induce severe heating effects on the electrodes of the stripline kicker. Based on theoretical derivations and CST simulations, this work systematically evaluates the longitudinal beam coupling impedance, effective impedance, loss factor, total parasitic power loss, and electrode thermal power deposition of the kicker, and subsequently performs an impedance-optimization study. The results show that both the total parasitic power loss and the electrode thermal power deposition are significantly reduced after structural optimization, with the loss factor notably improved for various bunch lengths. Further temperature-rise and mechanical-deformation analyses indicate that the maximum electrode temperature remains below the safe operating threshold for copper electrodes, and that the deformation induced by thermal expansion has a negligible impact on the electromagnetic field. In summary, the optimized stripline kicker continues to satisfy the design requirements under the high-current operation conditions of the STCF.

Speaker: Yan Wang (Huazhong University of Science and Technology)

WEP1622_edited_version.pdf

16:00 Beam-loading compensation at transition crossing for mixed intensity bunches

To produce beam for the nTOF and East Area experimental facilities at CERN, the Proton Synchrotron (PS) simultaneously accelerates two bunches with very different intensities. This combined acceleration cycle gains time and flexibility for beam sharing across the accelerator complex. However, to fulfil the demanding beam requests for future facilities like the Search for Hidden Particles (SHiP) experiment, a higher bunch intensity delivered to nTOF is essential to maintain the average flux at a reduced repetition rate. This further increases the intensity difference with respect to the low-intensity bunch for the East Area. In this contribution, longitudinal dipole oscillations triggered by the intensity-dependent phase jump at transition crossing are exposed. A mitigation technique is derived analytically and demonstrated in beam tests, by tuning one cavity of the main RF system to a separate harmonic of the revolution frequency. This allowed the elimination of dipole oscillations at transition crossing and the preservation of beam quality, even with a significant increase of the nTOF bunch intensity.

Speaker: Alexandre Lasheen (European Organization for Nuclear Research)

WEP5112_edited_version.pdf

16:00 Beamline Extension Considerations for AREAL-50 Accelerator

AREAL linear accelerator, presently operating at CANDLE SRI generates 5-MeV ultrashort electron beams for a wide range of applications. The planned upgrade program aims to increase the beam energy up to 50 MeV in order to expand experimental capabilities and enable the generation of THz radiation. For this purpose, two 1.6-m-long accelerating structures are foreseen to be installed. To ensure optimal beam parameters for efficient acceleration and high-quality beam delivery, existing magnetic and diagnostic systems must be modified and supplemented. In this paper, several aspects of the new beamline design are examined, and the corresponding beam dynamics studies for the proposed layout are presented.

Speaker: Mrs Milena Yazichyan (Center for the Advancement of Natural Discoveries using Light Emission)

WEP5004_edited_version.pdf

16:00 Beamstrahlung and Pair Production Under IP Aberrations at the FCC-ee

Beamstrahlung and secondary pair production are relevant sources of backgrounds but can also be exploited as potential tuning signals at the FCC-ee. They depend on possible interaction point (IP) optics errors and on general beam–beam conditions. Using GUINEA-PIG, we simulate beamstrahlung photons, and pair production through Breit–Wheeler, Bethe–Heitler, and Landau–Lifshitz processes and analyse the spectra, emitted power, and pair count for different sets of IP aberrations, including waist shift, vertical dispersion, and transverse coupling. The resulting photon and pair energy–angle distributions are examined, where comparisons with analytical expectations allow for consistency checks. We also compare GUINEA-PIG beamstrahlung predictions with multi-turn results delivered by the newly adopted code Xsuite, for a further benchmarking of Xsuite's beam-beam simulation package. Our study sheds light on possible beamstrahlung-related signals at the FCC-ee, including electron-positron pair production, and their dependence on the quality of the IP optics tuning.beamstrahlung-related signals at the FCC-ee, including electron-positron pair production, and their dependence on the quality of the IP optics tuning.

Speaker: Vaibhavi Gawas (European Organization for Nuclear Research)

WEP5046_edited_version.pdf

16:00 Bench-marking the Xsuite code with beam polarization data of the Large Electron Positron collider

The 26.7 km long Large Electron Positron collider (LEP) was operated at CERN between 1989 and 2000. The most precise measurements of the Z boson mass and width were made possible thanks to high precision energy calibration of the LEP beams with resonant depolarization. Transversely polarized beams had to be established at LEP to achieve this goal, providing a rich legacy of data on polarized beams at beam energies around 45 GeV. The beam dynamics simulation package Xsuite was recently enhanced to track polarized beams and to evaluate the equilibrium polarization of beams and related quantities. Xsuite code benchmarking with LEP results on transverse polarization and resonant depolarization will be presented in this contribution.

Speakers: Giovanni Iadarola (European Organization for Nuclear Research), Jorg Wenninger (European Organization for Nuclear Research)

WEP5003_edited_version.pdf

16:00 Benchmarking beam dynamics simulations for the MYRRHA Phase 1 accelerator

At the Nuclear Research Center SCK CEN in Belgium, the first phase of the MYRRHA project (an accelerator driven system) is under construction. Included in MYRRHA Phase 1 are a 17 MeV normal conducting injector linac (RFQ + CH cavities) and a super conducting linac (60 single spoke cavities), providing a CW proton beam of 4 mA at 100 MeV.
In this contribution, beam dynamics simulations of the MYRRHA Phase 1 accelerator are compared for four different beam dynamics codes: TRACEWIN, pyORBIT3, DYNAC and pyACCEL. The beam simulation results for a reference case are compared, as well as the computing times. Furthermore, approximations which can be made to speed up the computation times are discussed. These comparisons are made in view of a future on-line deployment of a simulation tool during beam commissioning.

Speaker: Lennert De Keukeleere (Belgian Nuclear Research Centre)

WEP6154_edited_version.pdf

16:00 Benchmarking of the PENELOPE/PENH and PHITS codes for calculation of beam quality correction factors in therapeutic proton beams

This work benchmarks the PENELOPE/PENH (2021 version) and PHITS Monte Carlo codes for calculating beam quality correction factors (kQ) in therapeutic proton beams. The latest PENH extension to PENELOPE enables proton transport simulation, including an approximate description of nuclear reactions and neutron production. PHITS, conversely, is an established multi-particle transport code covering protons, neutrons, and electron-gamma showers. The study compares simulated absorbed doses and kQ factors by modeling three configurations: a thin reference water cavity, a plane-parallel air cavity, and a cylindrical air cavity (representing typical ionization chambers). To determine the kQ factors, simulations involve a 1.25 MeV photon reference beam (Cobalt-60) and a 150 MeV monoenergetic proton beam. The computed results are validated against equivalent simulations published in the literature and obtained using FLUKA and GEANT4/TOPAS. This comparison assesses the suitability and consistency of the PENELOPE/PENH and PHITS codes for accurate clinical proton beam dosimetry.

Speaker: Dr Yuri Kubyshin (Universitat Politècnica de Catalunya)

WEP5129_edited_version.pdf

16:00 Benchmarking the linear lattice of the ISIS RCS as a foundation for future model-based optimisation

ISIS operates an 800 MeV Rapid Cycling Synchrotron (RCS) delivering protons to neutron and muon targets with a beam power of 0.2 MW. A reliable lattice description is essential for advancing low-loss, high-intensity operation and supports emerging model-driven optimisation enabled by forthcoming Python-accessible controls. A new consolidated low-intensity linear optics model of the ISIS RCS, developed through a continuous programme of systematic measurement-based benchmarking, is presented.

Using enhanced analysis of low-intensity turn-by-turn BPM data, multiple optics measurements have been integrated into a single self-consistent lattice representation. This lattice represents a significant advance over earlier design-only or partially benchmarked descriptions, enabling clearer identification of optics discrepancies and guiding targeted correction measures, including improvements to magnet survey and alignment.

The resulting reference lattice, implemented in MAD-X/cpymad and cross-checked with PTC-PyORBIT, reproduces low-intensity optics with improved predictive performance, particularly for orbit response and optics control. Benchmarks of the consolidated model, resulting improvements, and planned implementation in model-based optimisation of ISIS RCS operation are presented.

Speaker: Haroon Rafique (ISIS Neutron and Muon Source)

WEP5058_edited_version.pdf

16:00 Benchmarking the PENH Monte Carlo Code Against PHITS: Assessment of Proton Depth-Dose

This study provides a benchmark of the PENELOPE/PENH (2021 version) Monte Carlo code for proton transport using reference results from the established PHITS code. The comparison focuses on absorbed-dose distributions generated by a finite-spot proton pencil beam. Integrated depth-dose curves were simulated for monoenergetic beams ranging from $100 \text{ to } 250 \text{ MeV}$ incident on a water phantom. The degree of agreement between PENH and PHITS is quantitatively assessed for depth-dose behavior. The results evaluate PENH’s accuracy and establish its suitability for general proton transport applications.

Speaker: Dr Yuri Kubyshin (Universitat Politècnica de Catalunya)

WEP5130_edited_version.pdf

16:00 Beta Function Measurements using Quadrupole Variation in SLS 2.0

The Swiss Light Source upgrade, SLS 2.0, is a fourth generation storage ring based on a seven-bend achromat design and is currently under commissioning. Precise knowledge and control of the linear optics are essential for optimal machine performance. This contribution presents measurements of the beta function using the quadrupole variation method at 264 locations around the ring. The corresponding tune shifts were determined with high resolution via the mixed BPM technique combined with Numerical Analysis of Fundamental Frequencies (NAFF).

Speaker: Jesus Avila Pulido (Paul Scherrer Institute)

WEP5051_edited_version.pdf

16:00 Bootstrapping Injection Conditioning Study for FCC-ee Collider

Because of the strong beam-beam force at the interaction points in the FCC-$ee$ collider, the charge balance of two beams opposing each other is vitally important. The injection of a high charge beam derives the imbalance of two beams, which causes the instability of the beams. To avoid this imbalance, the bootstrapping injection has been adopted for the FCC-$ee$ collider. The conditioning of the bootstrapping injection is being performed as a part of the design study of FCC-$ee$. For simulating the top-up injection, the quasi-strong-strong beam-beam method is implemented in the full lattice simulation code SAD.
In this report, the charge threshold of the injection beam for each collision mode are presented. Also, the implementation of the quasi-strong-strong simulation are explained.

Speaker: Takashi Mori (High Energy Accelerator Research Organization)

WEP1605_edited_version.pdf

16:00 Bunch lengthening with double- and triple-rf systems for MAX4U

MAX IV is engaged in the design of a major upgrade to its 3 GeV ring, called MAX 4U. The upgrade aims at an improvement in light source performance to maintain MAXIV’s competitive edge beyond the end of this decade. In this contribution, we report on the studies of the performance of double- and triple-rf systems for bunch lengthening with MAX4U parameters. The stationary bunch profiles and longitudinal instabilities thresholds were evaluated with semi-analytical methods and benchmarked with macroparticle tracking simulations for different settings of the harmonic rf cavities.

Speaker: Murilo Barbosa Alves (MAX IV Laboratory)

16:00 Bunch shortening simulations by RF modulation in the EIC Beam Accumulator Ring

High single-bunch charge in the EIC Beam Accumulator Ring (BAR) leads to strong impedance-induced bunch lengthening that exceeds the requirements for injection into the Rapid Cycling Synchrotron. Using geometric and resistive-wall impedance model and multi-particle tracking with ELEGANT, we study RF phase-jump schemes that rotate the longitudinal phase space to transiently shorten the bunch before extraction. The simulations show that an appropriately timed phase jump can compress the bunch into the required bunch-length and energy-spread window while maintaining transverse stability.

Speaker: Victor Smaluk (Brookhaven National Laboratory)

WEP1327_edited_version.pdf

16:00 Bunch-by-Bunch Charge, Position, and Phase Diagnostics Using an Oscilloscope-Based Analysis for ALBA

The ALBA synchrotron is preparing its upgrade to ALBA II, a fourth-generation storage ring that will require improved bunch by bunch beam diagnostics in order to fully characterize the beam. To meet these requirements and based on the analysis developed using the HOTCAP code [1], we are integrating an oscilloscope-based analysis tool that processes BPM signals to extract bunch-by-bunch charge, transverse position, and relative changes of the longitudinal phase. This report summarizes how the tool has been adapted for ALBA, including possible bunch length measurements. We show results using this method and compare them with respect to other techniques.

Speaker: Javier Bañuelos Sánchez (ALBA Synchrotron (Spain))

WEP6069_edited_version.pdf

16:00 Bunch-by-Bunch Phase Pick-Up System in the SPS

As part of the High-Luminosity LHC (HL-LHC) project, the Super Proton Synchrotron (SPS) Low-Level RF (LLRF) system has undergone a major upgrade during the machine shutdown in 2019-20 to meet the performance requirements of the LHC ion program and high-intensity proton beams. A key development in this context is the implementation of a bunch-by-bunch measurement chain, designed to provide high-resolution diagnostics and bunch-by-bunch phase feedback capability.

This tool is particularly valuable for the ion slip-stacking RF manipulations where precise bunch-masking is required. In addition, it serves as a diagnostic tool to investigate beam loading effects by directly comparing the cavity voltage with the phase evolution of individual bunches. The system is implemented on the MicroTCA platform and employs 5 Gsps digitization of the beam signal from a wall current monitor (WCM).

This paper presents the operational results and commissioning challenges of the new acquisition and phase loop system.

Speaker: Arthur Spierer (European Organization for Nuclear Research)

WEP6117_edited_version.pdf

16:00 Capabilities and Limitations of Non-Redundant Aperture Interferometry for Beam Size Measurements

Non-Redundant Aperture Interferometry (NRAI) is a beam characterization technique developed at ALBA in collaboration with radio-astronomy institutes. It enables the single-acquisition measurement of the full 2D transverse profile of the electron beam using visible synchrotron radiation. To better understand the technique limitations and performance, we performed extensive SRW simulations and compare them with experimental data. This paper presents the results of these studies, which define the capabilities and limits of NRAI applied to the current ALBA machine, as well as its feasibility for the ALBA II upgrade.

Speaker: Laura Torino (ALBA Synchrotron (Spain))

WEP6068_edited_version.pdf

16:00 Causal GP-MPC: Where Structure, Safety, and Online Learning Meet for Robust Accelerator Control

Robust accelerator control increasingly relies on data-driven optimisation, yet balancing adaptability with safety remains challenging. Simulation-driven physics-informed reinforcement learning (RL) relies on soft constraints without firm safety guarantees, and classical matrix inversion becomes suboptimal under noise and hard actuator limits. Using the AWAKE electron beam steering task at CERN as a high-fidelity benchmark, we formulate beam steering as a stochastic control problem in a linear Markov Decision Process with continuous state and action spaces and realistic constraints, and compare classical inversion, Model Predictive Control (MPC), data-driven Gaussian-Process MPC (GP-MPC) and RL.

Our main contribution is a Causal GP-MPC scheme that embeds the beamline’s causal layout directly into the GP prior and kernel design. This structural inductive bias reduces model complexity, improves conditioning, and enables accurate multi-step prediction from limited data. In simulation studies based on the measured response matrix, Causal GP-MPC achieves performance comparable to MPC with the perfect model while requiring only observational data. It outperforms unstructured GP-MPC and RL baselines in sample efficiency, noise robustness, and online optimisation time. Taken together, these results demonstrate that causally structured learning offers a promising pathway toward data-efficient, interpretable, and deployable control strategies for complex accelerator systems.

Speaker: Simon Hirlaender (University of Salzburg)

WEP6096_edited_version.pdf

16:00 Cavity Failure Compensation Study in Spiral 2 LINAC: Simulation and Experimentation

The SPIRAL2 LINAC at GANIL (Caen, France) was commissioned in 2019 and became operational for users in 2022. During these years, there have been various issues with amplifiers and cavities, which have caused the LINAC to operate without a cavity. Within the framework of the ReFilL project, several cases with one cavity out of order were simulated with TraceWin. Three cases were tested experimentally in 2024 with a 5mA deuterium beam.
In 2025, following a leak in the cavity CMA11, the LINAC has been operated without this cavity for two months. Demonstrating the feasibility of cavity failure compensation under operational conditions. We fully characterized the CMA11-out-of-order configuration, and investigated two additional cases with a second inactive cavity: CMA01--CMA11, CMA11--CMA12. In both cases, nominal beam energy was successfully recovered.
This article presents results of these studies and perspectives for cavity compensation at GANIL.

Speakers: Mr Alexandre Leduc (Grand Accélérateur National d'Ions Lourds), Dr Angie Orduz (Grand Accélérateur Nat. d'Ions Lourds)

WEP5005_edited_version.pdf

16:00 Challenges in beam coupling impedances for FCC-ee

A comprehensive impedance model is required to ensure beam stability and optimize performance in the FCC-ee main rings. The model integrates contributions from a wide range of components, accounting for both resistive-wall and geometric effects. In this paper, we discuss the main challenges introduced by the peculiar FCC-ee parameter regime. A first difficulty arises from the combination of large beam-pipe dimensions and very short bunch lengths, which drives wakefield simulations into an extremely demanding computational regime, where very fine spatial resolution is necessary to accurately capture the beam–environment interaction. In addition, the beam-pipe cut-off lies within the frequency range excited by the FCC-ee beam. As a consequence, several higher-order modes may propagate over long distances, leading to non-local impedance effects and possible crosstalk between different accelerator elements. This means that the impedance environment cannot be treated as purely local, but requires a distributed description and an assessment of how propagating power is transported and potentially absorbed within the machine.

Speaker: Carlo Zannini (European Organization for Nuclear Research)

WEP5102_edited_version.pdf

16:00 Challenges in Electron Beam Diagnostics with Turbo-ICT at Petawatt-Class Laser Facilities

Laser-plasma acceleration (LPA) is a transformative approach in high-energy physics, promising applications from nuclear isomer production to medical treatment, astrophysics, and beyond. However, accurate, in-situ measurement of the accelerated electron beam charge remains fundamentally challenged by the intense operational environment. At ELI-NP, the Turbo-Integrating Current Transformer (Turbo-ICT) was deployed for this task. Despite its advantages, critical limitations were encountered. Our presentation therefore focuses on the influence of the intense laser-driven electromagnetic pulse (EMP)—a fundamental collateral phenomenon inherent to ultra-intense laser–plasma interactions—which generates substantial electromagnetic interference (EMI), induce nonlinear signal distortions, and limits the operational reliability of the Turbo-ICT in a high-energy, timing-jitter–sensitive environment. Initial measurements with Möbius loop antennas indicate EMP amplitudes span a broad range, peaking inside the interaction chamber with persistent components in adjacent zones. These findings quantify the detrimental influence of EMP-induced coupling on diagnostic performance and shot-to-shot correlations. We outline our mitigation strategy for these effects. This work advances the development of robust online diagnostics, addressing the lack of reliable shot-by-shot diagnostics for high-repetition-rate experiments, thereby enhancing precision methodologies for this demanding regime.

Speaker: Dr Vanessa Ling Jen Phung (Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering, Extreme Light Infrastructure - Nuclear Physics)

16:00 Characterization of Beam Loss at MAX IV In-Vacuum Insertion Devices

Four Libera Beam Loss Monitors (BLMs) were installed downstream of in-vacuum insertion devices at MAX IV 3 GeV storage ring. The monitors were operated in counting mode, with the loss-detection threshold defined from measurements taken with no stored beam. The BLMs were configured to provide stable, high-dynamic-range loss detection.

A series of controlled studies was performed to compare the loss signatures produced by different operational events, including beam scrape-downs, full beam dumps, full beam injections, and regular top-up cycles. The measurements show that scrape-downs generate the highest localized loss rates, while beam dumps produce almost no detectable signal at the BLM locations. Top-up injections exhibit consistent and repeatable loss patterns, providing a useful benchmark for routine operation. All events were studied with the insertion device gaps both closed and open; a significant decrease in detected losses was observed when the gaps were opened, demonstrating the strong influence of the local lattice and ID configuration on loss propagation.

These results provide a baseline of understanding of local loss behaviour downstream of the IVUs, and will also provide more refined future operational procedures.

Speaker: Michael Holz (MAX IV Laboratory)

WEP6132_edited_version.pdf

16:00 Characterization of longitudinal electron beam quality at the soft X-ray beamline of SwissFEL

Longitudinal electron beam quality is key at X-ray free-electron lasers (FELs), where electron beams with small slice energy spread and a well-preserved current profile are required to ensure optimal, stable performance. Collective effects such as microbunching instability (MBI) and intrabeam scattering (IBS) can significantly degrade the longitudinal phase-space of the electron beam during multi-stage compression and are therefore a concern across FEL facilities. In this contribution, we will present systematic characterization studies of these mechanisms at the SwissFEL soft X-ray beamline Athos. We will show longitudinal phase-space measurements using radiofrequency transverse-deflecting structures for different accelerator and compression conditions. These characterization studies represent a first step towards the optimization of multi-stage compression schemes aimed at mitigating MBI and IBS effects.

Speaker: Roberta Provvedi (Paul Scherrer Institute)

WEP5114_edited_version.pdf

16:00 Chromaticity compensation of a ghost collider

The GHOST collider final focus system is a pure quadrupole-drift beamline targeting $\beta^* = 2$ mm at four serial interaction points, with peak $\beta$-functions reaching ${\sim}65$ km in the final triplet. Beam tracking simulations reveal that a nominal bunch develops a pronounced C-shape in longitudinal phase space at IP1, where $\sigma_z$ grows from $0.15$ mm to ${\sim}2.3$ mm—a factor of ${\sim}15\times$ increase that directly reduces luminosity. This mechanism is identified as chromatically amplified betatron path length, where off-momentum particles acquire enlarged betatron amplitudes in the high-$\beta$ final triplet, generating excess path length via the geometric $\Delta z = - \frac{1}{2} \int (x'^2 + y'^2) \, ds$ integral. Within the monoenergetic Balandin framework, $\epsilon^2\xi_2$ with $\xi = - \frac{1}{2} \int \gamma \, ds$ dominates $\epsilon^2W^2$ by over four million times; the full beam $\sigma_z$ is a further factor of ${\sim}27$ larger, driven by $\sigma_\delta$-induced chromatic amplitude growth. Phase-advance scans confirm that $\sigma_z$ is insensitive to the apochromatic ($W \approx 0$) condition, and when combined with the geometric hourglass effect, this distortion poses a significant challenge to maximizing luminosity within the current lattice design.

Speakers: Bamunuvita Gamage (Thomas Jefferson National Accelerator Facility), Dr Peter Williams (Cockcroft Institute)

WEP1313_edited_version.pdf

16:00 Cleaning turn-by-turn data from the LHC with autoencoders

Turn-by-turn (TBT) BPM data in the LHC is often affected by noise, limiting the extraction of resonant driving terms (RDTs) and reducing the precision of nonlinear optics studies. We developed a denoising autoencoder trained on simulated tracking data to reconstruct clean transverse oscillations and suppress noise directly in the time domain. The method produces cleaner frequency spectra and significantly improves RDT visibility compared to established methods such as singular value decomposition, even when trained on fewer turns. In its current form, the autoencoder performs well on data that resemble the training set. However, when applied to new conditions—different noise levels, excitation amplitudes, tunes, or beam configurations—its ability to generalise decreases. These results demonstrate that autoencoders can substantially improve TBT data quality. Establishing broader and more diverse training datasets is a promising next step toward applying this technique to real LHC measurements.

Speaker: Joshua Gray (European Organization for Nuclear Research)

WEP5043_edited_version.pdf

16:00 CMOS camera-based observation and characterization of multipacting during Cavity Conditioning

Raspberry Pi cameras (single board CMOS cameras) have already been successfully implemented for ion beam characterization at IAP Frankfurt and are now also being used to investigate multipacting during cavity conditioning. Multipacting appears caused by resonant secondary electron emission.
For the standalone rf conditioning of the FRANZ (Frankfurt Neutron Source) RFQ (Radio-Frequency Quadrupole) and the IH-DTL (Interdigital H-mode Drift-Tube-Linac), these cameras were installed both inside and outside the vacuum to detect multipacting and other cavity glowing effects. The occurrence of multipacting at specific power levels within the cavities can be confirmed by simulations.
In addition, the observed multipacting is characterized through spectrometer measurements.

Speaker: Leonie Bauer (Goethe University Frankfurt)

WEP6055_edited_version.pdf

16:00 CNN-based arrival time determination in piled-up particle counter signals

Pulse pile-up limits the count rate, timing precision, and energy resolution of radiation detection systems in accelerator beam instrumentation and downstream experiments. We present the project status of a machine-learning based pile-up recovery system designed for real-time particle counting and time of arrival determination at pulse rates exceeding $10^7$~particles/s. The convolutional neural network (CNN) architecture utilized in this project is trained on labelled scintillator data to identify pulses in the piled-up waveforms. This development is primarily aimed at beam spill characterization at GSI/FAIR using plastic scintillators, however the concept presented is general-purpose and could be applicable to any radiation detector. First model implementation is performed on the FPGA onboard a commercial digitizer and its performance is compared against the single threshold leading-edge discriminator.

Speaker: Rahul Singh (GSI Helmholtz Centre for Heavy Ion Research)

WEP6047_edited_version.pdf

16:00 Coherent electron Cooling experiment at Relativistic Heavy Ion Collider

Vladimir N Litvinenko for CeC team
Coherent electron Cooling (CeC) has potential to provide strong cooling for high energy hadron beam. Coherent electron Cooling experiment at Relativistic Heavy Ion Collider (RHIC), started about 10 years ago, went through a number of significant modification and it will end by the end of January 2026 with the end of RHIC operations. In this presentation we will discuss advances and challenges in CeC demonstration.

Speaker: Vladimir Litvinenko (Stony Brook University)

16:00 Coherent Oscillation Simulations of Beam Instability Generated During Debunching for J-PARC Slow Extraction

The J-PARC Main Ring (MR) has achieved a high extraction efficiency above 99.5% during 30 GeV slow extraction at the current beam power of 92 kW (8.1x10^13 ppp). However, at beam powers above 30 kW, we observed ring-wide beam loss due to transverse beam instability associated with vacuum pressure rise and electron cloud, believed to be triggered by longitudinal microwave structure in the beam. To achieve stable operation, we implemented phase offset injection into RF buckets and a two-step RF voltage reduction technique for debunching, in addition to chromaticity control. The generation of the longitudinal microwave structure and coherent transverse oscillation by the electron cloud during debunching has been investigated using a newly developed simulation code. The simulation predicts the generation of the longitudinal microwave structure under known ring coupling impedances. The code models the electron cloud–beam interaction as a transverse impedance derived from an assumed neutralization factor. The simulation results will be compared with measurements from a wall current monitor and a beam position monitor. Through this study, we will explore further instability mitigation strategies toward higher beam intensity operations planned for the future.

Speaker: Ryotaro Muto (High Energy Accelerator Research Organization)

WEP4606_edited_version.pdf

16:00 Coherent Transverse Instabilities on the ISIS Proton Synchrotron at Injection Energy

ISIS is the short-pulsed spallation neutron and muon source at the Rutherford Appleton Laboratory in the UK. Its rapid-cycling synchrotron accelerates up to 3e13 protons per pulse from 70 to 800 MeV at 50 Hz, delivering them to fixed targets for neutron and muon production. As a beam-loss limited facility, increasing operational intensity necessitates the reduction of beam losses. Although largely mitigated, a coherent vertical instability continues to drive losses at high intensities and remains an active area of research.

Having recently identified a likely source of the instability's driving impedance, we re-examine observations of instabilities on ISIS when operating as a storage ring at its injection energy. We present the updated vertical driving impedance model, compute analytical predictions of instability growth rates excluding space-charge effects with the PyTMCI Vlasov solver, and compare these with experimental observations across a range of vertical tune settings. We also outline future development plans.

Speaker: David Posthuma de Boer (ISIS Neutron and Muon Source)

16:00 Collective Effects and Impedance Update for the Diamond-II Storage Ring

Impedance and collective effects are significant concerns for the design of modern accelerators. During development of the Diamond-II storage ring, effort was initially focussed on design for the arcs containing the majority of magnets, and geometric impedance was focussed on single bunch effects. We now present updates to the Diamond-II impedance database and the impact on collective effects including additional detail in straights, including injection, insertion devices and RF elements, as well as inclusion of long-range impedance for more elements for multibunch dynamics.

Speaker: Dmitrii Rabusov (Diamond Light Source)

WEP5104_edited_version.pdf

16:00 Commissioning at the tunes below half-integer for CSNS RCS

Based on the beam commissioning of CSNS-I RCS, the current tune above half-integer exhibits extremely small parameter margins and severe instabilities. Therefore, to further increase beam power in Phase II, significant optimization of the tune is required.​​​​Through extensive simulations, we identified that the tunes below half-integer (near 4.3/5.3) show no instabilities, which is crucial for power enhancement in Phase II. To verify stable operation at the tunes of this region in the actual machine, we conducted a series of machine studies. The results demonstrate that the tunes below half-integer is instability-free and can achieve stable beam supply at 140 kW (corresponding to 700 kW in Phase II under equivalent tune shift due to space charge).​

Speaker: Jianliang Chen (Chinese Academy of Sciences)

WEP4639_edited_version.pdf

16:00 Commissioning of BEPCII Upgrade

The upgrade of Beijing Electron and Positron Collider-II has begun since the shutdown of BEPCII on July 1st in 2024. The hardware replacement and upgrade is expected to finish by the end of the year 2024, and the machine commissioning of BEPCII upgrade project will start at the beginning of the year 2025. In this paper, we will show the commissioning results of the BEPCII uprade project.

Speaker: Haisheng Xu (Institute of High Energy Physics)

WEP1606_edited_version.pdf

16:00 Commissioning of the FAIR Control Centre

The FAIR Control Centre (FCC) has been purpose-built on the GSI campus to meet the complex operational demands of the FAIR/GSI large scale accelerator facility. It hosts the Main Control Room (MCR), seminar and meeting rooms of various sizes, offices, and dedicated technical rooms.
The 640 m² MCR is an open, collaborative workspace for accelerator experts, experiment teams, and technical staff. It offers a 24/7 ergonomic environment with ad-vanced acoustic and climate control, height-adjustable consoles, and a water-cooled IT infrastructure. In addi-tion to the console displays, the fully digital MCR fea-tures ca. 110 m² of high-resolution LED overview dis-plays for system-level visualization.
Construction of the MCR was completed in November 2025. Console installation began on December 8th, fol-lowed by IT installation and commissioning in early 2026. Initial operation of the first consoles was per-formed in late February, with full MCR operation target-ed for June 2026. The GSI accelerators will be controlled from the FCC for the beam time starting in September.
We report on the FCC key features and the project sta-tus on its path to completion, with an emphasis on com-missioning.

Speaker: Vsevolod Kamerdzhiev (GSI Helmholtz Centre for Heavy Ion Research)

WEP6100_edited_version.pdf

16:00 Commissioning of the FERMI Electro-Optical System for time-resolved beam profile measurements

The Electro-Optical Sampling (EOS) system uses the electro-optic effect to map the transient field of the beam onto a probe laser pulse, enabling direct reconstruction of the temporal current distribution.

Temporal profiles acquired with the EOS were compared with independent measurements from the RF deflector, used as the reference diagnostic. The two techniques show good agreement in pulse duration, peak position, and main temporal features, with minor differences attributed to their intrinsic resolution and coupling conditions. These results confirm that the EOS is fully operational and provides reliable time-domain diagnostics complementary to the deflector, non invasive and compatible with the operation

Speaker: Giovanni Campri (Elettra-Sincrotrone Trieste S.C.p.A.)

16:00 Commissioning of the IOTA proton injector

The Proton Injector for the IOTA storage ring (IPI) has been successfully constructed and commissioned at the Fermilab Accelerator Science and Technology (FAST) facility. It has demonstrated the capability to produce proton pulses of up to 14 mA at 2.5 MeV. Operating alongside with the existing electron injector, IPI enables expanded beam physics research and supports the development of novel accelerator technologies at the IOTA ring. This report presents the results of IPI’s construction and commissioning, as well as an overview of the experimental program using intense proton beams at IOTA.

Speaker: Aleksandr Romanov (Fermi National Accelerator Laboratory)

WEV4301_edited_version.pdf

16:00 Commissioning the Passive Structure Wakefield Dechirper on CLARA

A passive energy dechirper has been installed on CLARA, a 250 MeV electron beam user facility at Daresbury Laboratory. The device, comprising two orthogonal sets of planar dielectric-lined waveguides, is designed to manipulate the longitudinal phase space of the electron bunch, reducing energy spread and thereby delivering higher quality beams for user experiments. We present preliminary results from initial commissioning of the dechirper with the CLARA beam, including measurements of the wakefields excited and changes in longitudinal phase space due to the dechirper. We outline plans for further measurements and discuss how the dechirper will support upcoming user programs.

Speaker: Toby Overton (Science and Technology Facilities Council)

WEP6091_edited_version.pdf

16:00 Compensation of second-order random resonances in the J-PARC RCS

In the J-PARC 3-GeV rapid cycling synchrotron, second-order random resonances are excited by shifting the operating point to a higher tune side. To mitigate resonance-induced beam loss and further enhance tunability of the operating point, we studied the compensation of second-order resonances. By controlling the timing when the beam approaches resonance through adjusting the momentum offset and chromaticity-induced tune shift, the optimal resonance compensation is explored, considering the time dependence of lattice imperfections that drive the resonances. The analysis of resonance driving terms and numerical simulation was employed to deepen the understanding of the lattice imperfections. In this article, details of the method and experimental results will be reported.

Speaker: Kunihiro Kojima (Japan Atomic Energy Agency)

WEP4604_edited_version.pdf

16:00 Computing coherent synchrotron radiation from Liénard-Wiechert potentials

The linac-based test accelerator FLUTE contains a bunch compressor to create few-fs scale bunches that generate coherent radiation in the THz regime. The form and spectrum of the THz pulse strongly depend on the evolution of the bunch along the bunch compressor, and hence on the paths of the particles. From a given path of a charged particle, one can compute the emitted radiation by means of the Liénard-Wiechert potentials. A problem with this approach is that one needs to solve an implicit equation for the retarded time. Here, we instead compute the retarded time from the particle time and observer position. Furthermore, the Liénard-Wiechert potentials depend on the acceleration, while macro-particle tracking only yields the particle positions and momenta at fixed times. To compute the acceleration, we interpolate the data by twice differentiable functions. We compare the numerical results to the analytical benchmark case of synchrotron radiation. Finally, we compute the coherent radiation emitted of simulated bunches during compression.

Speaker: Axel Bernhard (Karlsruhe Institute of Technology)

WEP5080_edited_version.pdf

16:00 Conceptual Design and Performance Study of Two-Plane Multi-Turn Injec-tion for High-Intensity U²⁸⁺ Beams in SIS18

Within the FAIR project, SIS18 is planned to be used as an injector and booster to increase the intensity of ion beams. To achieve higher intensities, a two-plane multi-turn injection scheme for SIS18 is being developed at GSI. The new injection system will allow a substantial increase in the number of accumulated turns with high efficiency, significantly reducing beam losses at the electrostatic septum (ES). This paper presents the conceptual design of the two-plane injection system and the results of studies on the expected properties of the U²⁸⁺ beam delivered from the upgraded UNILAC, including its parameters after collimation in the TK transfer line. Furthermore, the paper discusses the design requirements for the injection line and the anticipated performance of the two-plane injection system in SIS18, taking into account the beam optics of the injection line, collimation effects, and overall injection efficiency.

Speakers: David Ondreka (GSI Helmholtz Centre for Heavy Ion Research), Oleksiy Dolinskyy (GSI Helmholtz Centre for Heavy Ion Research)

WEP5014_edited_version.pdf

16:00 Conceptual Design for the Combined Damping and Accumulator Rings for Positrons at STCF

The Super Tau-Charm Facility (STCF) is a new generation tau-charm factory designed to collect an enormous and unique dataset in the tau-charm energy region. In order to supply high-quality electron and positron beams to the collider, the STCF injector employs a compatible injector scheme that supports both off-axis and swap-out injection modes. This paper introduces the conceptual design of a combined damping and accumulator rings for positrons at the STCF, aimed at meeting low-emittance beam requirements.The damping ring (DR) and the accumulator ring (AR) share the same lattice, and aligned vertically to reduce construction costs. The detailed lattice design of the DR and AR are presented in this paper.

Speaker: Mingxuan Chang (Institute of Modern Physics, Chinese Academy of Sciences)

WEP1619_edited_version.pdf

16:00 Conceptual design of a 2.45 GHz ECR ion source for proton therapy

Proton therapy has attracted increasing attention because of its favorable dose distribution enabled by its Bragg-peak behavior. Motivated by the proton therapy facility project at Shanghai Synchrotron Radiation Facility (SSRF), a 2.45 GHz ECR ion source has been designed and fabricated. This paper presents the conceptual design of the prototype, together with simulation results of the magnetic field configuration, the ridged waveguide and the beam extraction.

Speaker: Xiaoxia Huang (Shanghai Synchrotron Radiation Facility)

WEP4646_edited_version.pdf

16:00 Conceptual Design of a Compact 425 MHz Injector for Helium Therapy facility

A new 425 MHz injector has been designed for proton and helium therapy facility. The LINAC consisted of a 3.0 m length RFQ and a 2.8 m length IH-DTL, which was designed to accelerate H2+ and He2+ beams to 8 MeV/u. The beam dynamics of the linac were designed based on comprehensive 3D electromagnetic field simulations, followed by particle tracking to optimize beam quality and transmission efficiency. Multi-physics analysis investigated thermal effects on cavity resonant frequencies.

Speaker: Yusen Guo (Shanghai Synchrotron Radiation Facility)

WEP4617_edited_version.pdf

16:00 Continuous and Automated Monitoring of the Health and Performance of the LHC Beam Position Monitor System

We have developed a new automated system to continuously monitor the health and performance of the LHC Beam Position Monitors (BPMs) at CERN. We preprocess turn-by-turn and bunch-by-bunch data through denoising and normalization before analyzing it using a combination of basic quality tests with rule-based checks and anomaly detection algorithms. All real-time acquisitions are processed on a dedicated python node, with results stored in HDF5 format and aggregated via our offline analysis framework that offers also visualization and reporting functionality. Our system provides robust diagnostics, daily summaries, and dashboards to ensure BPM reliability and maintain high data quality throughout LHC operations.

Speaker: Javier Martínez Samblas (European Organization for Nuclear Research)

WEP6077_edited_version.pdf

16:00 Continuous operation of Cryogenic Current Comparators at FAIR

Cryogenic Current Comparators (CCC) are superconducting devices for beam current monitoring, based on azimuthal magnetic field (fT range) measurement with ultrasensitive SQUID magnetometers. They are able to provide a calibrated non-destructive measurement of beam current with a resolution of 10 nA or better, independent from ion species and without tedious calibrations procedure.
We have developed the CCC over the last ten years in an international collaboration with the goal of a highly sensitive and continuous current measurement in the transfer lines and rings at FAIR and CERN machines. Besides the efforts to improve the robustness and current resolution of the device, investigations have been performed on the cryogenic support system, which has to provide stand alone operation in HEBT tunnels without He supply. So far we have achieved standing times in the range of 6 - 9 months after liquid He filling, recently we have demonstrated stand alone He liquefaction from gas bottles within ~ 4 weeks, which would avoid He filling in the tunnels. In this contribution we present the status and results of our current work with focus on the cryogenics aspects.

Speaker: Thomas Sieber (GSI Helmholtz Centre for Heavy Ion Research)

WEP6048_edited_version.pdf

16:00 Control of Nonlinear Tune Shifts in SLS 2.0

The Swiss Light Source upgrade, SLS 2.0, is a next-generation storage ring featuring an ultra-low-emittance lattice based on a seven-bend achromat design. Achieving such low emittance requires strong focusing, which in turn generates large negative chromaticities. These are corrected using powerful sextupole magnets, introducing nonlinear effects in the beam dynamics. In particular, amplitude-dependent tune shifts (ADTS) and chromatic tune shifts (CTS) play a significant role. This contribution presents measurements of ADTS and CTS performed using high-precision tune measurements. Furthermore, since SLS 2.0 comprises 12 sectors equipped with 22 octupoles each, the control of ADTS and CTS through the use of octupoles is demonstrated.

Speaker: Jesus Avila Pulido (Paul Scherrer Institute, École Polytechnique Fédérale de Lausanne)

16:00 Coupled-bunch instabilities with a defocusing higher-harmonic RF system

Coupled-bunch instabilities restrict the beam intensity in many synchrotrons. These limitations can be mitigated by adding a higher-harmonic radiofrequency (RF) system, which modifies the potential well. Of particular interest is the bunch lengthening mode (BLM), in which the higher-harmonic voltage produces a defocusing effect at the bunch centre. By decreasing the peak line density, space-charge effects are reduced in hadron synchrotrons, while Touschek scattering is mitigated in synchrotron light sources. This contribution investigates the impact of a higher-harmonic RF system in BLM on the intensity threshold, growth rate, and mode behaviour of coupled-bunch instabilities. The influence of beam parameters such as the bucket filling factor, narrowband impedance properties, and RF system configuration is highlighted. Regimes in which BLM is advantageous or disadvantageous are compared to the ones for a single-harmonic RF system. The comparisons are based on semi-analytical solutions of the Vlasov equation as well as macro-particle simulations using the BLonD code.

Speaker: Ruben Heine (Technische Universität Berlin)

WEP5107_edited_version.pdf

16:00 CST modeling of traveling-wave chopper structures for LANSCE and LAMP

The Los Alamos Neutron Science Center (LANSCE) accelerator complex delivers both protons and negative hydrogen ions with various beam time patterns simultaneously to multiple users. An upgrade of its front end to a modern, RFQ-based version – a part of the LANSCE Accelerator Modernization Project (LAMP) – is now in the conceptual design stage. The LAMP will need fast beam choppers both in the low-energy transport (LEBT, 100 keV) before RFQ, and in the medium-energy transport (MEBT, 3 MeV) after RFQ. We use CST to model the existing LANSCE plate-coax helix chopper at 750 keV and to develop fast traveling-wave current structures for LAMP MEBT and LEBT beam choppers. A few structure types: plate-coax helix, meander-folded stripline on high-dielectric-constant substrate, and double-helix like at FNAL – are considered and compared. The structures must provide short rise / fall times of the deflecting electric field (1-ns class in MEBT), while still making possible for the chopper pulse generators to deliver the required voltages at high repetition rates.

Speaker: Sergey Kurennoy (Los Alamos National Laboratory)

WEP4346_edited_version.pdf

16:00 Current classification strategies based on the transfer function and field quality of the new superconducting magnets in the HL-LHC

Precise optics control around the main interaction regions of the HL-LHC is essential to reach the target values of $\beta^*$ and the collider's nominal performance, while maintaining sufficient beam aperture and satisfying machine protection constraints. The field quality of the high-luminosity insertion-region magnets is critical for the accelerator performance, possibly impacting the achievable integrated luminosity. In this context, magnet sorting strategies, i.e. the allocation of a compatible slot in the tunnel based on the actual magnet properties, such as the transfer function and magnet field quality, can provide an effective handle to improve both linear and non-linear optics performance of the upgraded insertion regions. This work focuses on the Q2 magnets of the HL-LHC inner triplets, which are built at CERN and for which sorting remains a feasible option, as it is compatible with production and installation schedules. The effectiveness and trade-offs of these approaches are studied using a combination of analytical calculations and full HL-LHC lattice simulations. The results of the studies performed lead to an effective sorting recommendation for the Q2 units, which is adopted for the installation and operation in the HL-LHC era.

Speaker: Massimo Giovannozzi (European Organization for Nuclear Research)

16:00 Current Profile Reconstruction by Passive Streaking of Low Charge, Low Energy Electron Bunches in Dielectric Loaded Waveguides

Advanced accelerating techniques are evolving rapidly, enabling high energetic electron beams with significantly decreasing footprint. While the accelerating structures shrink impressively, longitudinal diagnostic components with femtosecond resolution like transverse deflecting structures still demand a significant amount of space and complex infrastructure, are costly and require precise synchronization of their power source with the arriving electron bunch.

The TWAC project¹ aims for a fully-integrated compact accelerator, delivering ultrashort bunches (≈10s of fs) at low charge and energy (10 pC, 10 MeV), requiring corresponding small footprint, cost-efficient longitudinal diagnostics. Here, the retained method is passive streaking in dielectric loaded waveguides² in which the self-excited transverse wakefields are imposing a varying kick dependent on the intra-bunch longitudinal position. The new parameter regime is investigated at the ARES linac, firstly at medium energy (≈60 MeV). A novel forward propagation reconstruction algorithm has been developed, based on a waveguide mode expansion with more than 100 modes to properly model the excited wake.

Speaker: Max Joseph Kellermeier (Deutsches Elektronen-Synchrotron DESY)

16:00 Damping Higher Order Modes for the Cool Copper Collider

For next generation particle collider designs, such as the Cool Copper Collider, small beam sizes, short bunch spacing, and beam stability are required to reach the luminosities desired to search for new physics. One challenge to overcome is damping the excitation of higher order modes in accelerating cavities. These modes are excited by wakefields induced by the beam, and must be removed before they are seen by the following bunch to prevent deflecting kicks that will spoil beam stability. The solution is the addition of damping slots on the accelerator cavities that can couple to these higher order modes and remove them from the central part of the cavity that the beam passes through, to reduce the kick factor of the mode. Additionally, these damping slots can lower the Q value for these modes, causing the excitation to die out between bunches because the mode cannot resonate in the cavity for as long. In this study, we optimize the damping slot geometry to remove higher order modes from the accelerating cavity while preserving the fundamental accelerating mode.

Speaker: Sophia Morton (SLAC National Accelerator Laboratory)

WEP1342_edited_version.pdf

16:00 Data-Driven Optimization of Open Loop Control Functions at the CERN Super Proton Synchrotron

To minimize beam intensity loss during a cycle in the CERN Super Proton Synchrotron (SPS), several machine parameters must be adjusted as functions of cycle time, spanning injection, injection plateau, acceleration, and extraction plateau. Today, these functions are typically tuned manually – a cumbersome procedure that can require hours of operator effort. This paper presents the progress towards automatically tuning time-dependent parameter functions. Using Bayesian optimization (BO), we aim to minimize intensity loss throughout the cycle with intensity measurements as the primary feedback signal. We report results from applying this method to an intentionally detuned machine development beam in the SPS, as a step towards deployment on the operational fixed-target beams. The approach is generic and applicable to time-dependent parameter optimization problems in other machines.

Speaker: Adrian Menor de Onate (European Organization for Nuclear Research)

WEP6016_edited_version.pdf

16:00 Data-driven reconstruction of accelerator lattice errors using three beam position monitors

There are numerous experimental techniques to quantify errors in a particle accelerator so that they can be corrected to improve the performance of the accelerator. However, these techniques are often limited in scope, for example, identifying only the errors in quadrupole strengths, sextupole strengths, or the centers of these magnets. In this paper, we propose a data-driven method that can estimate many parameters of lattice elements, including those mentioned above, based solely on many sets of transverse position readings in a section that spans three beam position monitors. Preliminary simulation results will be reported.

Speaker: Guimei Wang (Brookhaven National Laboratory)

WEP5303_edited_version.pdf

16:00 Deep Lie map networks from single-pass forward differentiation

Deep Lie Map Networks (DLMN) were introduced in earlier work as an optimisation framework that adjusts lattice parameters by fitting simulated beam trajectories to measured BPM data. In this contribution, we present a new implementation of DLMN based on the single-pass forward differentiation capability of MAD-NG, allowing exact derivatives of the particle coordinates with respect to lattice parameters to be computed during tracking. Unlike approaches that rely on back propagation or finite differences, this method performs gradient evaluation directly inside the symplectic tracking engine. This enables efficient gradient-based fitting of lattice parameters with improved memory efficiency and reduced computation time. The work demonstrates that differentiable, symplectic tracking provides a powerful foundation for data-driven optics modelling and establishes DLMN-in-MAD-NG as a scalable tool for future accelerator studies. Looking ahead, this framework could form a key component toward a real-time digital twin of accelerator lattices, where machine settings and model parameters are continuously inferred from live measurements.

Speaker: Joshua Gray (European Organization for Nuclear Research)

WEP5042_edited_version.pdf

16:00 Defining the new FCC-ee baseline optics

The Future Circular electron-positron Collider (FCC-ee), with a circumference of approximately 91 km, is being rapidly developed by CERN and its collaborators. Two collider-ring optics proposals have been developed in parallel over recent years. Each proposal features its own strengths and challenges.
The Global Hybrid Correction optics (GHC) came first with a ring-distributed correction of the horizontal chromaticity generated in the Interaction Regions (IRs), using many sextupole pairs. A local conventional chromaticity correction section is used in the IR for the vertical plane.
The more recent Local Chromaticity Correction (LCC) scheme proposal uses both vertical and horizontal chromatic correction sections in the IRs and keeps a modular design.
A comparison process was carried out between late 2025 and early 2026 to prepare for the review process of the
FCC-ee baseline magnetic lattice and optics in view of the Technical Design Report. This contribution presents the comparison process of these two optics designs from the perspective of beam dynamics and performance.

Speaker: Jacqueline Keintzel (European Organization for Nuclear Research)

WEV1001_edited_version.pdf

16:00 Design and optimization of a horn focusing system for efficient pion capture in a Muon Collider Demonstrator

This study investigates magnetic horn focusing as an alternative to superconducting solenoids for the Muon Collider Demonstrator. We explored a double horn structure as an R&D exercise for a possible muon-collider frontend, tailored to capture pions in the 100-400 MeV/c momentum range. An XGBoost-based optimization pipeline was applied to refine geometric and current parameters to maximize pion yield while maintaining acceptable emittance. To validate performance, we benchmarked the single horn structure against IMCC design baselines and compared the optimized double horn structure with the solenoid channel, using Geant4 and FLUKA simulations. The results provide a critical assessment of the trade-offs between the lower-cost magnetic horn approach and superconducting solenoids, offering a potential pathway for a more economically viable Muon Collider Demonstrator.

Speaker: Prateek Rao (University of Wisconsin–Madison)

WEP1349_edited_version.pdf

16:00 Design and Performance Analysis of the Upgraded Transfer Line for Two-Plane Injection at the SIS18.

Two-plane multiturn injection is planned for SIS18 to enable the delivery of high-intensity heavy-ion beams, which will subsequently be accelerated and extracted toward SIS100 at a repetition rate of 2.7 Hz. To accommodate this new injection scenario, the existing SIS18 injection line must be redesigned to allow simultaneous injection into both the horizontal and vertical planes of the synchrotron. Ion-optical studies have been performed to evaluate the expected performance of the upgraded injection system, and the results are presented in this paper. The simulations demonstrate that the injection efficiency strongly depends on the emittance and transverse beam distribution of the beam delivered from UNILAC. Furthermore, a mismatch between the injected orbit and the equilibrium orbit defined by the transfer line optics leads to additional efficiency degradation. The paper discusses the impact of beam collimation in the transfer line, analyzes the sensitivity of the injection efficiency to various mismatch scenarios, and provides guidance for optimizing the two-plane multiturn injection process for SIS18.

Speaker: Oleksiy Dolinskyy (GSI Helmholtz Centre for Heavy Ion Research)

WEP5012_edited_version.pdf

16:00 Design and Performance of a MicroTCA-Based LLRF Hardware Platform for the ALBA Synchrotron at the 1.5 GHz Third Harmonic

This work presents the hardware design and performance evaluation of a new Low-Level Radio Frequency (LLRF) system developed for the ALBA synchrotron, operating at the third harmonic frequency of 1.5 GHz. The system is implemented on a MicroTCA (uTCA) platform and is composed of a Rear Transition Module (RTM) that performs the analog front-end processing and down-conversion to an intermediate frequency, together with an Advanced Mezzanine Card (AMC) that digitizes the RF signals at high speed and provides all digital interfaces required by the control system. The hardware platform supplies all necessary resources for the ALBA firmware team to instantiate their own DSP algorithms, feedback loops, synchronization blocks, and machine-specific control strategies, ensuring full flexibility for future developments.
This work describes in detail the architecture of the designed hardware, including clock distribution, signal conditioning, conversion stages, digital interfaces, and integration within the uTCA ecosystem. Experimental results are presented both from laboratory characterization and from commissioning tests performed at the ALBA synchrotron. These results demonstrate that the system meets the required performance in terms of stability, noise, linearity, dynamic range, and timing accuracy, validating the suitability of the developed LLRF hardware for high-precision accelerator operation.

Speaker: Juan Fernández (Safran Electronics & Defense Spain S.L.)

16:00 Design and Recent Developments of the Electron Storage Ring for the Electron-Ion Collider

The Electron-Ion Collider (EIC), which is currently being designed for construction at Brookhaven National Laboratory, will collide polarized electron beams (5-18 GeV) with polarized hadron beams (41-275 GeV for protons) at luminosities up to $10^{34} \textrm{cm}^{-2} \textrm{s}^{-1}$ in a 3.8-kilometer ring. The EIC will be the only lepton-hadron collider since HERA at DESY and, in contrast to that earlier machine, will feature high polarization of both electrons and protons, a wide range of center-of-mass collision energies, a wide range of ion species, and much higher luminosities. These properties will make it an ideal machine for exploring the mass and spin dynamics of nucleons. The Electron Storage Ring (ESR) will be built in the existing 3.8-kilometer RHIC tunnel using normal-conducting magnets and a few superconducting magnets for the final-focus quadrupoles and spin-rotator solenoids. The wide range of energies, high polarization, high current, large beam-beam parameters, and stringent geometric constraints make the ESR a particularly challenging machine. Lately, the design of the ESR has advanced considerably with design alternatives and upgrade paths being considered to align with the key deliverables and funding profile of the project. This contribution highlights some of the important recent developments and design studies.

Speaker: Daniel Marx (Brookhaven National Laboratory)

WEP1332_edited_version.pdf

16:00 Design of a 1 GeV superconducting proton linac based on Nb3Sn Technology

A 1 GeV superconducting proton linac is being proposed as a driver for an accelerator driven system (ADS) for nuclear waste transmutation. In 2014, a compact design for an ADS driver linac based on state-of-the-art Niobium superconducting RF technology was developed at Argonne National Lab. Since then, a new and transformational SRF technology has emerged based on Nb3Sn material. The new technology offers similar performance to Niobium but at higher operating temperatures with the potential of significantly reducing the operation costs of future linac-based accelerator facilities. The goal of this study is to re-design the original ADS driver linac to take advantage of Nb3Sn technology. The accelerating cavity types, operating frequencies and dimensions will be revised. It also involves the physics design of the new linac for efficient acceleration and focusing, and performing end-to-end beam dynamics simulations at full beam energy and current.

Speaker: Delvon Alexander (Illinois Institute of Technology)

16:00 Design of a compact 8-MeV proton linac for medical applications

A 714 MHz proton linac was designed for medical applications. The linac aims for both sychrotrons and S-band linacs. Proton beams can be accelerated to 8 MeV with high transmission.

Speaker: Yixing Lu (Shanghai Synchrotron Radiation Facility)

WEP4616_edited_version.pdf

16:00 Design of a dual extraction system for the ultra-compact multifunctional cyclotron CYCIAE-36A

The growing demand for medical isotopes and mobile neutron sources has motivated the development of compact and multifunctional accelerators. The China Institute of Atomic Energy has developed an ultra-compact superconducting cyclotron, CYCIAE-36A, capable of accelerating H₂⁺ and α particles and delivering proton and α beams for applications including ²¹¹At production, PET isotope supply, α-irradiation studies, and neutron imaging. The highly compact layout poses significant challenges for beam extraction. A dual extraction system combining electrostatic deflection and carbon-foil stripping is proposed under the constraints of superconducting magnets, RF cavities, and limited space. In this scheme, α particles are extracted using an electrostatic deflector, while H₂⁺ ions are extracted by stripping, enabling variable-energy proton beams in the opposite direction. Phase width control is critical for extraction efficiency. A fixed-phase selector was implemented in the central region to optimize α-beam extraction. Particle tracking simulations starting from the central region assume phase widths of 20° for α particles and 50° for H₂⁺ ions, yielding extraction efficiencies of 65% and 99%, respectively. In addition, the effects of 1st and 2nd harmonic magnetic field components introduced by the magnetic channels during precession extraction were analyzed, and corresponding compensation methods were developed to mitigate their impact on beam dynamics.

Speakers: Dr Tianjue Zhang (China Institute of Atomic Energy), wei fu (China Institute of Atomic Energy)

WEP4633_edited_version.pdf

16:00 Design of a High-Energy Electron Cooling Scheme and Beam Dynamics Study for HIAF-BRing

To address the beam quality deterioration of high-energy, high-intensity ion beams in HIAF-BRing caused by heating effects such as intra-beam scattering (IBS), a high-energy electron cooling scheme based on an energy recovery linac (ERL) is proposed. In this scheme, the ERL is used to generate high-quality electron beams, which are then injected into an electron storage ring for multi-turn circulation, allowing repeated interactions with the ion beam to accumulate the cooling effect. The overall layout of the ERL-based cooling system in BRing, the matching of key beam parameters, and the cooling performance are systematically analyzed. Beam dynamics simulations indicate that the proposed scheme can effectively suppress IBS-induced beam heating in the relativistic energy regime and significantly shorten the cooling time, enabling the ion beam quality to meet the design requirements.

Speaker: Mr Zhiqiang Zhang (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Design progress of STCF injector

We present the recent progress on the injector design for the Super Tau-Charm Facility (STCF). As an integral part of the STCF accelerator complex, the injector is a sophisticated accelerator system. Its primary role is providing high-quality, full-energy electron and positron beams for injection into the collider rings, serving as a key component for realizing high luminosity at the STCF. We report the injector design for both off-axis injection and bunch swap-out injection.

Speaker: Duan Gu (Shanghai Advanced Research Institute)

16:00 Design Refinements And Prototyping Of Lead Shielding For The FCC-ee Arc Dipoles

In the Future Circular Collider (FCC-ee) at CERN, lead shielding will be required on the collider arc dipoles around synchrotron radiation (SR) absorber locations to reduce radiation levels in the tunnel and protect sensitive components. The shielding assemblies will be mounted around the yokes, where scattered SR photons are expected to deposit 10-15 MW of power in total (across all absorber locations combined over the entire collider) at the tt-bar operating point. Between the yokes and the shielding, a water-cooling system will be integrated to cool both the shielding and the magnet. Recent design studies have focused on refining the geometry and cooling layout to simplify manufacturing, control costs and maintain shielding performance. A shielding prototype is planned to inform design choices and further improvements. This contribution presents the design evolution, plans for a prototype, and cooling system optimisations.

Speaker: Thomas Banks (European Organization for Nuclear Research)

WEP1017_edited_version.pdf

16:00 Determination of the sPHENIX background source with tracking

During the Relativistic Heavy Ion Collider (RHIC) Run 24 operations with
100 GeV/u Au beams, significant backgrounds were observed at the sPHENIX
MAPS-based VerTeX (MVTX) detector. Extensive studies were performed dur-
ing RHIC operation to diagnose the source of the background. Through track-
ing simulations, the primary source of the backgrounds were found and removed
prior to beam operations for Run25. The removal of the obstruction resulted in
a reduction of backgrounds by an order of magnitude, similar to the best miti-
gation found during Run24. The tracking simulations that showed the location
of the obstruction and the resulting background reduction following its removal
are shown.

Speaker: Kiel Hock (Brookhaven National Laboratory)

WEP1308_edited_version.pdf

16:00 Determining the influence of transversal beam excitation on beam size and dynamics at KARA

Significant beam dynamics parameters, such as energy spread or transversal beam size, can be calculated from the transversal bunch profile.
At the Karlsruhe Research Accelerator (KARA), located at the Karlsruhe Institute of Technology (KIT),
the beam size in the storage ring is being investigated using the KArlsruhe Linear arraY detector for MHz rePetition rate SpectrOscopy (KALYPSO), a line array that examines the synchrotron radiation emitted at a five-degree port of a dipole magnet.
Trench-Isolated Low-Gain Avalanche Diode (TI-LGAD) technology provides superior sensitivity compared to conventional silicon detectors, thereby facilitating the study of low-charge bunches.
As the KALYPSO system can be triggered at several megahertz, turn-by-turn analysis can be performed at KARA, which has a revolution frequency of 2.7 MHz.
In addition to the study of the energy spread, the analysis of beam size and position modulations can be performed. These can either occur naturally or be induced by a white noise signal on a strip line.
In this contribution, the influence of transversal beam excitation on beam size and time-resolved dynamics at KARA is investigated.

Speaker: Julian Gethmann (Karlsruhe Institute of Technology)

WEP6040_edited_version.pdf

16:00 Detuning estimation for a doubly-fed normal-conducting gun

At the European Free-Electron Laser (EuXFEL) superconducting linac, a revised normal-conducting gun design with symmetrical feed was successfully installed and tested. Thermal expansion of the solid copper body dominantly affects the detuning transients of this cavity. To improve accuracy, and add time resolution over the duration of a pulse, we implemented and tested an observer that estimates the resonance frequency over time using a parameter-identified white-box model of the RF network. Results were validated against forward and reflected power couplers, cavity voltage, and an algebraic stationary approximation.

Speaker: Max Herrmann (Deutsches Elektronen-Synchrotron DESY)

WEP6148_edited_version.pdf

16:00 Developing a Physics-Informed Gaussian Process Model to Construct an Uncertainty-Quantified Machine Model Using Bayesian Optimization

For maintaining the designed optical performance of machines like the GSI heavy-ion synchrotron SIS18 or the FAIR fragment separator SFRS, accurate knowledge of magnetic field and element alignment is crucial. A Gaussian Process model with a physics-informed kernel based on a stochastic ensemble of lattices is proposed.
Key advantages compared to LOCO (Linear Optics from Closed Orbits) include (1.) fitting of Gaussian probability distributions for parameters, which inherently model uncertainty, (2.) incorporation of measurement uncertainty from BPM noise, (3.) uncertainty-enabled orbit prediction between BPMs, and (4.) an active-learning strategy for greater sample efficiency than measuring an orbit response matrix. Applied in a simulation of SIS18, the method constructs an effective machine model with minimal orbit uncertainty around the ring, enabling orbit correction with uncertainty-quantified minimal deviation at any location. The SFRS is identified as a compelling target for future application, where sparse instrumentation and complex optics make uncertainty-aware modeling particularly valuable.
This physics-informed GP framework provides uncertainty-enabled modeling for rings and beamlines, with potential applications extending to broader optics-correction and beam-tuning tasks.

Speaker: Victoria Isensee (Technical University of Darmstadt)

16:00 Development of a Gas-Target Laser Ion Source Test System for the LaPRIS Concept

In order to achieve high energy resolution in nuclear physics experiments, it is important to maintain the beam quality during beam transport from the injector to the accelerator and to the experimental instruments. At the Research Center for Nuclear Physics (RCNP), the University of Osaka, high-resolution beams are currently obtained by injecting beams from an ECR ion source into the accelerator and collimating them with slits throughout the acceleration. However, this method leads to increase losses of beam intensity and a beam halo, so it is desired to generate high-quality beams directly at the ion source without collimations.
As a solution to the issues, we are developing the LaPRIS (Laser Plasma RF Ion Source) method. LaPRIS is a pulsed ion source that generates and extracts slow ions by combining a gas jet, an RF field and ultra short pulse laser. In this method, the ions are extracted from plasma generated at the laser focal spot by RF field. They form a short-pulsed bunch with a small spatial and time profile.
In this paper, we will discuss preliminary results obtained by generating laser-induced plasma through focused laser in a jet of thin gas and measuring the generated ions.

Speaker: Shotaro Matsui (The University of Osaka)

WEP4647_edited_version.pdf

16:00 Development of STCF High-Efficiency Positron Capture Traveling Wave Accelerating Structures

The Super Tau-Charm Facility (STCF) is a next-generation electron-positron collider under development, with a designed center-of-mass energy of 2–7 GeV. Positrons generated by a high-energy electron beam striking a target are captured and accelerated to 200 MeV using large-aperture traveling-wave accelerating structures to reduce beam loss. A constant-aperture cavity geometry, in which the group velocity is controlled by the nose-cone length, is proposed to simplify fabrication while maintaining a high accelerating gradient. A pulse compressor is incorporated into the RF system to further enhance the effective RF power. This paper presents the RF design and optimization of 2 m and 3 m large-aperture accelerating structures, both achieving gradients above 15 MV/m.

Speaker: ShaoHang Ma (University of Science and Technology of China)

WEP1613_edited_version.pdf

16:00 Development of STCF S-Band High-Gradient traveling wave accelerating structures

The Super Tau-Charm Facility (STCF) is a next-generation electron-positron collider project proposed in China, designed to explore frontier physics in the tau-charm energy region. The facility's accelerator is required to provide electron and positron beams with tunable energies ranging from 1.0 to 3.5 GeV. This study presents the design of a traveling-wave accelerating structure for the STCF. By optimizing the regular-cell configuration, a high shunt impedance is achieved. The peak electric field in accelerating structure is reduced by adjusting the accelerating gradient profile, and an under-coupled output coupler design is adopted to enhance the performance of the accelerating structure. The objective is to achieve an accelerating gradient of 22.5 MV/m with an input power of 45.3 MW, and to further increase the power in pursuit of high-gradient operation in the S-band.

Speaker: ShaoHang Ma (University of Science and Technology of China)

16:00 Development of the 2 MeV Proton Beam Diagnostics Section in Preparation for Neutron Production at FRANZ

The Frankfurt Neutron Source (FRANZ) at the Institute for Applied Physics in Frankfurt (IAP) is advancing toward the commissioning of proton beams up to 2 MeV. To support beam tuning behind the RFQ–IH acceleration chain, a dedicated diagnostics section is being installed downstream of the IH structure. The setup focuses on transverse beam characterization using scintillation screens combined with radiation-tolerant camera systems, enabling multi-angle (two-view) imaging of the proton beam under various beam-current and RF settings. Additional instruments include phase probes for energy and RF-phase monitoring, as well as a Faraday cup for current measurements. The camera-based diagnostics are designed to provide reliable visual feedback during early commissioning, particularly in an environment with limited access and the radiation levels typical for this region of the accelerator. This contribution presents the concept, implementation approach, and intended diagnostic capabilities of the camera-driven setup as FRANZ prepares for subsequent steps toward routine 2 MeV operation and the following delivery of the proton beam onto the lithium target for the first neutron production campaigns.

Speakers: Adem Ates (Goethe University Frankfurt), Leonie Bauer (Goethe University Frankfurt)

WEP6054_edited_version.pdf

16:00 Development Progress on the Digital BPM Processor for Hefei Advanced Light Facility

The Hefei Advanced Light Facility (HALF) is a fourth-generation synchrotron radiation light source in the low-energy region, based on a diffraction-limited storage ring. The high stability requirements for the beam orbit in a diffraction-limited storage ring necessitate that the digital beam position monitor processor (DBPM) achieve high-precision measurements. While compensating for inter-channel inconsistencies, the total latency must be minimized to enable fast orbit feedback control. The dual-pilot frequency technique is used in HALF's DBPM to compensate for channel inconsistencies and improve measurement resolution. Additionally, the hardware and software algorithm designs have been optimized to balance resolution and latency, ensuring that the latency is less than 90 μs while meeting resolution requirements. The development and fabrication of the prototype and engineering prototype have been completed. This paper will introduce the hardware and software design of the self-developed DBPM, along with laboratory test results and beam test results conducted at the Shanghai Synchrotron Radiation Facility (SSRF）. Both laboratory and beam test results meet the specifications. During beam test, the horizontal and vertical turn-by-turn (TBT) resolutions were 467.53 nm and 447.47 nm; the horizontal and vertical fast acquisition (FA) resolutions were 88.32 nm and 88.63 nm; and the horizontal and vertical slow acquisition (SA) resolutions were 44.60 nm and 43.60 nm.

Speaker: Xing Yang (University of Science and Technology of China)

16:00 Digital LLRF Control System for a High-Repetition-Rate Superconducting Linac

The development of high-repetition-rate superconducting linear accelerators for advanced light sources imposes stringent demands on the performance of the Low-Level Radio Frequency (LLRF) control system. This report presents the design, implementation, and operational results of a high-precision LLRF system developed for the Dalian Advanced Light Source (DALS) injector—a 1 MHz superconducting linac. The system employs a digital feedback architecture based on a field-programmable gate array (FPGA), enabling high-speed I/Q modulation and demodulation, vector summation, and low-latency feedback control to address the narrow bandwidth challenge posed by superconducting cavities with loaded quality factors up to 4.3×10⁷ (half-bandwidth ~15 Hz). High-resolution piezo actuators are integrated for active cavity tuning. During commissioning in August 2025, the system successfully stabilized ten superconducting cavities, supporting beam operation at over 100 MeV, 1 MHz repetition rate, and 0.1 mA current. Closed-loop amplitude and phase stabilities of better than 0.02 % and 0.02 ° were achieved per cavity, with total voltage maintained steadily at 110 MV. The results demonstrate the system’s robustness and precision, providing a valuable reference for future LLRF systems in next-generation high-repetition-rate light sources.

Speaker: Zhiyuan Zhang (Institute of Advanced Light Source Facilities, Shenzhen)

WEP6604_edited_version.pdf

16:00 Digital low level RF system for Elettra 2.0

The new digital electronics of the four Radio Frequency
(RF) plants for Elettra 2.0 (E2.0) is fully designed in house,
both hardware and firmware. The Digital Low-Level Radio
Frequency (DLLRF) works on a non-IQ sampling technique
and it is benefiting from the huge internal development
of a System On Chip (SoC) Field Programmable Gate Array
(FPGA) boards realized for the electron beam position
monitor electronics. Each RF plant will have its own machine
protection system based on FPGA board to minimize
the interlock intervention time. Initial tests of these new
electronics have been carried out during last run of Elettra,
however the complete commission is carried out using
the RF power plant available in the laboratory. This paper
presents the design choices and the performed tests that
confirm the achievements of the system’s specification.

Speaker: Cristina Pasotti (Elettra-Sincrotrone Trieste S.C.p.A.)

WEP6150_edited_version.pdf

16:00 Dilution Monitoring for the BDF-SHiP Target

The BDF/SHiP experiment requires precise monitoring of the beam dilution pattern on the high-power target absorbing up to 350kW (avg.). This paper presents the conceptual design of a dedicated Beam Dilution Monitor (BDM), which will enable observation of the circular beam sweep pattern during 400GeV/c proton operation. The proposed system is based on Secondary-Emission Monitor (SEM) grids comprising 12μm-thick titanium bands. Detailed simulations were performed to evaluate signal formation, thermal response, secondary-electron collection, and the detectability of dilution magnet failure scenarios. Different detector geometries and interlock strategies were also investigated, demonstrating that the proposed BDM concept can provide sufficiently fast and reliable detection of dilution failures.

Speaker: David Gancarcik (European Organization for Nuclear Research)

WEP6172_edited_version.pdf

16:00 Dispersion suppression for wedge-based final cooling at a 10 TeV Muon Collider

Reaching $10^{34}$ $\rm{cm}^{-2}s^{-1}$ luminosity range in a $10$ TeV Muon Collider within the short lifetime of the muon requires the reduction of the 6D emittance of the muon beam in a process described as muon ionization cooling. In the final cooling stage, the transverse emittance must be reduced to $22 \mu$m, typically by allowing longitudinal emittance growth up to downstream acceptance limits. While the current International Muon Collider Collaboration designs additionally involve $40$ T solenoids to reach the transverse emittance target, such high-field solenoids come with a number of disadvantages, including mechanical stress management, quench protection, and potential limitations in relying on High Temperature Superconductor technology. Designed as an alternative to using such solenoids while simultaneously reaching target transverse emittance, the previously proposed wedge-based, reverse emittance-exchange cooling scheme requires excellent dispersion suppression. In this study, we design and simulate a dispersion suppressor channel for the wedge-based final cooling design that reduces dispersion in the target direction to a target value of $D_x = 0.0036$ m.

Speaker: Inci Karaaslan (University of Chicago)

WEP1345_edited_version.pdf

16:00 Double RF system design using normal conducting passive harmonic cavity for SOLEIL II

Double rf systems are critical for achieving the parameters of fourth-generation synchroton light sources. These systems relax stochastic collective effects but also introduce instabilities, such as Robinson and periodic transient beam loading (PTBL) instabilities, which depend heavily on the cavity parameters. In the framework of the SOLEIL II project, we demonstrate how we can use semianalytical algorithms to predict and analyze these instabilities, in conjunction with multibunch tracking simulations, to optimize rf cavity parameters in high-dimensional parameter spaces, thereby maximizing the Touschek lifetime. Finally, the expected performances of the double rf system, using the optimized normal conducting passive harmonic cavity parameters, are presented.

Speaker: Alexis Gamelin (Synchrotron soleil)

WEP5092_edited_version.pdf

16:00 Dual-RF Phase Control for Adiabatic Energy Ramping in the EIC Rapid Cycling Synchrotron

The Electron-Ion Collider (EIC) Rapid Cycling Synchrotron (RCS) accelerates electrons from 750 MeV to 10 GeV over approximately 64.7 ms. While the baseline design simultaneously ramps both RF voltage and phase, this study evaluates an alternative where RF cavities are divided into two groups, each operating at a fixed 6.5 MV, with the effective voltage synthesized through phase control. In the symmetric scheme (Option A), both groups vary symmetrically about the synchronous phase to provide exact matching of energy gain and synchrotron tune throughout the ramp. Conversely, the asymmetric scheme (Option B) pins one group at the final operating phase while the other varies to supply the required energy gain. The feasibility of Option B is determined by the adiabaticity of the resulting synchrotron tune evolution, with ramp profiles, phase trajectories, and adiabaticity metrics analyzed for both implementations.

Speaker: Alexei Blednykh (Brookhaven National Laboratory)

WEP1314_edited_version.pdf

16:00 Effect of Broken Superperiodicity on Half Integer Resonance and Possible Compensation

With a perfect two-fold superperiodicity in a storage ring, the half integer resonance is not excited and can be overlapped by the beam tune spread induced, e.g., by beam-beam collisions in a collider or space charge in a hadron storage ring, without any detrimental effect on the beam.

If the superperiodicity of the quadrupolar lattice is broken, either by design or due to machine imperfections, a resonance stop band is created, which may lead to unstable particle motion.

Guided by historical literature, analytical calculations, and toy simulations, we explore the relation between single-particle motion and optics near the resonance. We discuss possible mitigation approaches including damping and cooling processes that suppress residual instabilities, defining pertinent tolerances for optics errors, and the construction of tuning knobs which can reduce the resonance strength. We also discuss fundamental and practical limits to resonance compensation.

Our discussion here focuses on the linear transverse optics. Chromatic resonance effects can be analysed in a similar way.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

WEP5040_edited_version.pdf

16:00 Effect of FCC-ee Optics Errors in Collision Simulated by Xsuite

The luminosity performance of FCC-ee is sensitive to spurious optics errors at the Interaction Point (IP), notably to nonzero waist shift, vertical dispersion, and transverse coupling. Using the code Xsuite, we study how these aberrations influence beam sizes, luminosity, and beamstrahlung power, for the FCC-ee baseline parameters. Multi-turn simulations have been carried out to study the equilibrium distribution/dynamics. Simulated sensitivities for linear lattice descriptions allow an assessment regarding the impact of strong-strong beam-beam effects on IP tuning. By scanning the amplitude of individual linear IP optics aberrations, we infer tolerance estimates for which the simulated performance remains compatible with the design expectations. We compare these with the results of earlier (single-pass) simulations by the code GUINEA-PIG and with analytical calculations. Our study aims at providing a consistent picture of beam–beam behaviour at the FCC-ee IP, so as to help devise future strategies for luminosity optimisation and IP tuning.

Speaker: Vaibhavi Gawas (European Organization for Nuclear Research)

WEP5045_edited_version.pdf

16:00 Effect of Interplane Correlation on the Two-Plane Multiturn Injection Efficiency

Beamlets provided by LINACs for injection into ring accelerators are subject to interplane correlation effects. Preliminary studies have shown that these correlations negatively affect the efficiency of 1-plane multiturn injection*. This study shows the effect of different grades of correlation between the transverse planes of the injected beamlets on the injection efficiency of 2-plane-multiturn injection at the simulation example of SIS-18.

Speaker: Annemarie Lauterbach (Goethe University Frankfurt)

WEP5021_edited_version.pdf

16:00 Effect on 7 TeV proton beams from the residual multipolar fields in the HL-LHC Hollow Electron Lens

Hollow electron lenses are a promising tool for controlling beam halo at high-intensity colliders like the HL-LHC. A perfect lens can efficiently deplete particles above the inner radius of the electron beam while leaving the core – which travels through a nominally zero-field region – unaffected. However, residual multipolar fields in the electron beam and non-ideal compensations of entry and exit regions of the electron beam can lead to emittance growth and other undesired effects on the circulating-beam core. This is a particular concern for the operation with pulsed electron beam currents that ensures the fasted depletion rates. In this study, updated two-dimensional field maps from recent studies at CERN's hollow electron beam test stand are used to quantify these effects under HL-LHC conditions. Beam-dynamics simulations are performed to evaluate the emittance evolution and identify the dominant field components contributing to core degradation. The analysis also considers compensation of the dipolar component using nearby electric kicker magnets.

Speaker: Chiara Maccani (European Organization for Nuclear Research)

WEP5118_edited_version.pdf

16:00 Efficient Five-dimensional Beam Sigma Matrix Determination Using Differentiable Simulation

Precise reconstruction of the beam sigma matrix is critical for transport-line modeling and injection optimization. Our earlier work demonstrated that the differentiable simulation framework Cheetah enables gradient-based recovery of the 5×5 transverse sigma matrix at the APS-U BTS transport line using quadrupole scans. In this paper, we extend the method to improve efficiency and robustness. We introduce a generalized formulation that incorporates multi-screen measurements, providing increased stability in realistic lattice configurations. The differentiable-tracking approach yields physically consistent reconstructions while remaining computationally scalable. These developments form a practical framework for sigma-matrix determination in complex transport lines and support future real-time model calibration and tuning at the APS-U and similar facilities.

Speakers: Osama Mohsen (Argonne National Laboratory), Yine Sun (Argonne National Laboratory)

WEP6303_edited_version.pdf

16:00 Efficient Parameter Reconstruction from Gaussian Pulses using a GPU

Pulse parameters such as height, width and peak time provide valuable information about the source. However, real-time evaluation is currently hardly possible for high repetition rates such as those as found in a synchrotron. In this contribution, we record the summed signal from beam position monitors at the Karlsruhe Research Accelerator (KARA) with the FPGA-based pulse digitizer KAPTURE-2 and demonstrate the efficient evaluation of Gaussian pulses.
To enable real-time analysis of the acquired signals, these must be processed quickly and efficiently. Therefore, the computational workload is accelerated using a GPU, leveraging its parallel processing capabilities. In addition, an approach for parallelization on the CPU is evaluated to determine its effectiveness compared to GPU acceleration. This comparison also evaluates two methods for bunch reconstruction - QR decomposition and gradient-based least-squares minimization.

Speaker: Julian Gethmann (Karlsruhe Institute of Technology)

16:00 Electromagnetic test-bench evaluation of pickup prototypes for the Elettra 2.0 button-type beam position monitors

To reliably and repeatably validate the electromagnetic behavior of the pickup prototypes designed for the Elettra 2.0 button-type beam position monitors, two different radio-frequency test fixtures have been developed. The first test fixture, based on a coaxial-line design that emulates the TEM excitation generated by a relativistic beam, allows to measure the transmission performance of the pickups up to 16 GHz. The second test fixture, employing an antenna-launcher design, extends the measurement range up to 40 GHz. This paper presents a comparison between measured and simulated data, with particular focus on the electromagnetic validation of the first 16 prototypes manufactured using glass as the dielectric material.

Speaker: Stefano Cleva (Elettra-Sincrotrone Trieste S.C.p.A.)

WEP6062_edited_version.pdf

16:00 Electron-Ion Collider (EIC) Project: An Overview on Recent Progress

The Electron–Ion Collider (EIC) Project is a top priori-ty for the U.S. Department of Energy (DOE) and is ex-pected to be completed in the 2030s. The EIC facility is designed to map the internal structure of nucleons (pro-tons and neutrons) to understand how quarks and gluons generate their properties. The EIC is being built at Brookhaven National Laboratory (BNL), in partnership with the Thomas Jefferson National Accelerator Facility (Jefferson Lab). The Project, supported by a large interna-tional user group, also promises advancements in artificial intelligence, medical imaging, and accelerator technology.
Currently the Project is progressing toward a mature accelerator design and is rapidly transitioning from design to construction. This paper provides a Project-level over-view of the accelerator design status highlights, recent accomplishments and path forwards.

Speaker: Luisella Lari (Brookhaven National Laboratory)

16:00 Empirical Orbit Correction for 3-GeV Proton Beam Transport in Fringe Field from Front Solenoid of Secondary Beamline

A 3-GeV proton beam from a rapid cycling synchrotron (RCS) is provided to muon and neutron production targets at Materials and Life Science Experimental Facility by a 3-GeV RCS to Neutron facility Beam Transport (3NBT) line in J-PARC. In the 3NBT line, the 3-GeV proton beam is deflected in the vertical direction due to fringe field of a large aperture solenoid for capturing secondary particles from the muon production target located approximately 30 m upstream of the neutron production target. For correcting the orbit deflection and eventually the vertical beam position on the neutron production target, the beam position was measured as function of excitation currents for the coils of the solenoid. In this presentation, we report results of the measurement analysis and the orbit correction based on the empirical analysis.

Speaker: Yuji Yamaguchi (Japan Atomic Energy Agency)

16:00 Enhancing Beam Time Availability by a Factor of Two: Simultaneous Operation of Hadron Physics and Detector Test Beam Lines at ELSA

The electron accelerator facility ELSA houses two external high-energy beam lines. These deliver primary electron beams with energies between 0.8 and 3.2 GeV, extracted via slow resonant extraction from a synchrotron to a total of three different experimental sites. One beam line hosts two hadron physics experiments, while the second, located on the opposite side of the synchrotron, is used for detector tests and medical physics experiments.

Recently a new operation mode has been developed to serve both external beam lines with an extracted electron beam simultaneously. This enables running detector test experiments at low rates (tens of kHz) alongside high-rate hadron-physics experiments at GHz extraction rates, significantly increasing beam time availability.

We present properties and underlying beam dynamics of this operation mode, with particular emphasis on advanced methods for rate control at the second beam line.

Speaker: Dennis Proft (University of Bonn)

WEP6053_edited_version.pdf

16:00 Error and Sensitivity studies for LANSCE Accelerator Modernization Project

The LANSCE Accelerator Modernization Project (LAMP) aims to modernize the existing LANSCE front-end technologies. Two existing 750-keV Cockcroft Waltons are planned to be replaced by a single radio-frequency quadrupole (RFQ), and a new 100 MeV DTL will be installed. The new LAMP front-end is required to deliver beams with similar timing patterns to what is currently delivered to the experimental stations. Using the physics model of the LAMP front-end, we evaluate errors and sensitivities of multiple transport components and study the effect on the beam instensity and timing.

Speaker: Dr Salvador Sosa Guitron (Los Alamos National Laboratory)

WEP4331_edited_version.pdf

16:00 Estimating the Stability Domain of Symplectic Maps: A Robust Method via Bounding Set of Unstable Initial Conditions

Estimating the stability domain in view of its characterization and optimization is one of the primary topics of single-particle non-linear beam dynamics. The border of the stability domain or dynamic aperture (DA) has a complicated fractal boundary that cannot be reliably estimated by analytical means. Instead, a numerical computation is used to estimate the DA with the additional constraint of determining only the simply connected domain around the origin. The most common case of a DA estimate for 4D systems can be reduced to a 2D polar grid scan, which reduces the computational burden. Here we present a new robust method of DA characterization by constructing a cloud of escaping initial conditions that bound the stable domain and has a significantly reduced computational complexity compared to a direct scan of phase-space variables. The proposed method is applied to a non-linear 4D symplectic polynomial map and the results compared against what found with the standard methods, both in terms of numerical accuracy and of CPU time.

Speaker: Ivan Morozov (Elettra-Sincrotrone Trieste S.C.p.A.)

WEP5028_edited_version.pdf

16:00 Estimation of the Required Dipole Corrector Magnetic Field for PIP-II Injection Based on Beam Studies

The Fermilab Booster will accept a 600 µs beam pulse from the new superconducting Linac for PIP-II operations. The Booster is a rapid-cycling synchrotron that uses a resonant magnet circuit ramping at 15 Hz. For PIP-II, the cycle rate will increase to 20 Hz, and the injection pulse length will expand from 40 µs to 600 µs due to the lower output current from the new Linac. Because the Booste main bending field follows a sinusoidal waveform, the magnetic field is not constant during the extended injection window. The longer pulse length and higher repetition rate modify the beam orbit and can lead to increased beam losses.

The Booster contains 48 dipole-corrector packages distributed across its 24 periods. Each package includes horizontal and vertical dipoles, quadrupole, sextupole, skew-quadrupole, and skew-sextupole elements. By driving the dipole correctors with an appropriately shaped sinusoidal waveform during injection, we can compensate the changing main field and create an effectively flat bending field—referred to as flat injection.

Over the past several years, machine studies have been performed to characterize the required correction fields and to determine the corresponding power-supply specifications needed for PIP-II operation. In this presentation, we will summarize the study results and discuss the estimated magnetic field requirements and power supply parameters for achieving flat injection in the Booster.

Speaker: Kiyomi Seiya (High Energy Accelerator Research Organization)

WEP4609_edited_version.pdf

16:00 Experimental Evaluation of a Digitizer Designed for ACCT Beam Current Transformers

To integrate the signals of beam current transformers into accelerator control systems, particle accelerators require high-performance digitizers with optimized bandwidth, sampling rate, and dynamic range. They must be accurate and reliable. And they should be easy to deploy and operate.

A specialized digitizer was developed to interface the Bergoz Instrumentation ACCT sensor and its analog front-end electronics to an accelerator control system. It allows waveform acquisition preserving the quality of the analog signal and controls the ACCT configuration. Communication is implemented over Ethernet through a simple command protocol, and an EPICS soft IOC is provided.

The digitizer was tested with two ACCTs installed at the CHUV Oriatron Linac and a third at the METAS electron beamline. Results demonstrate improved signal-to-noise ratio, adaptability to multiple beam types, and simplified deployment compared to general-purpose digitizers.

Speaker: Mr Dorian Coves (Bergoz Instrumentation (France))

WEP6031_edited_version.pdf

16:00 Exploiting Bluesky to Enhance Undulator Characterisation and Commissioning Processes at BESSY II

Undulators at BESSY II are routinely inspected for their impact on the machine tune and orbit, with the goal of ensuring tune and orbit feedforward tables remain fit for purpose. In particular this is necessary following modifications to the storage ring, as well as more obvious cases such as the installation of new devices and repositioning of existing devices. To that end a commissioning framework exploiting the Bluesky ecosystem has been established. Undulators and diagnostic hardware are represented through Ophyd device abstractions, and measurements are orchestrated as Bluesky plans with full metadata stored in a mongodb database with databroker. This has enabled the creation of an ID scan dataset for real time analysis during commissioning, rather than relying on post-hoc extraction of data from the Archiver for offline analysis. This work has also brought more consistency and better reproducibility of undulator scans, and provides the infrastructure required for more ambitious commissioning goals. It has also brought flexibility to commissioning scripts to take advantage of other innovations on the BESSY II machine and control environment. This paper outlines the application of this work to routine undulator commissioning and future goals to further simplify commissioning workflows.

Speaker: Ed Rial (Helmholtz-Zentrum Berlin für Materialien und Energie)

WEP6129_edited_version.pdf

16:00 Exploring convolutional neural network training strategies for pile-up correction in single particle counting

This work investigates the effect of different training strategies on the performance of convolutional neural networks (CNNs) for real-time pile-up identification and correction in single particle counters at the GSI Helmholtz Centre for Heavy Ion Research. Building on a previously developed CNN capable of detecting particle pulses without domain-specific knowledge, we examine the influence of different loss functions and their hyperparameters on the network’s ability to accurately localize overlapping events. We also propose new metrics for particle counting and show how to adapt common metrics for precision and recall to allow a user-defined localization tolerance. Using a dataset of approximately 26,000 manually labeled pulses, we analyze how these training choices impact particle counting and localization performance. The findings provide insights for developing particle counting systems suitable for real-time applications, including potential implementation on FPGA hardware.

Speaker: Tobias Habermann (Fulda University of Applied Sciences)

WEP6009_edited_version.pdf

16:00 Exploring Coupled-Cavity Linac upgrade with Distributed-Drive Linac at LANSCE

The Distributed-Drive Linac (DDL) concept allows independent control of the radiofrequency (RF) power and phase of each accelerator cell, realized by an RF power system consisting of discrete solid-state amplifiers (SSAs). The DDL concept is under investigation at Los Alamos Neutron Science Center (LANSCE) as a candidate for the future upgrade of the 805-MHz Coupled-Cavity Linac. Independently adjustable RF power and phase of each DDL accelerator cell allows using the same DDL architecture to provide a much higher beam energy at the linac exit, such as 2-3 GeV, for proton radiography (pRad). The DDL architecture would require significant upgrade of the RF infrastructure at LANSCE, including implementing a great number of phase-coherent coaxial transmission lines for 3000-5000 individual DDL accelerator cells. For the pRad operation mode, compact RF pulse compressors are also under investigation.

Speaker: Michael Kaemingk (Los Alamos National Laboratory)

WEP4313_edited_version.pdf

16:00 Extended Maintenance and Gradual Replacement of MIL-1553-based Field Network at GSI

The control system of the GSI accelerator complex dates back to the early 1990s.
It is based on a derivative of the MIL-1553 field bus, providing around 1 Mbit/s throughput and deterministic real-time operation.
Although a modern control architecture with smart front-ends (System Control Units, SCUs), Ethernet, and White Rabbit is now widely deployed at GSI, several hundred devices still depend on the legacy network and protocols.

The ageing electronics and limited bandwidth provide strong motivation to migrate to the new control system.
However, an upgrade is limited by various constraints: strict real-time operation, existing software architecture, physical space and available power sources. Therefore, operation of the legacy interfaces must be ensured for at least another decade while a unified migration strategy is hard to find.

In this contribution, we present a generic approach for extending the lifetime of the existing MIL-1553-based systems and gradual replacement of their components. This includes upgrades of bus controllers, device controllers, the bus itself as well as a new Modbus/TCP-based solution for simple devices.

Speaker: Mr Volker Kleipa (GSI Helmholtz Centre for Heavy Ion Research)

WEP6101_edited_version.pdf

16:00 Extraction and Injection in the Electron Injector for the Electron-Ion Collider

The electron injector for the Electron-Ion Collider (EIC) consists of a linear accelerator, a beam accumulation ring, and the Rapid Cycling Synchrotron (RCS) before the electrons are injected into the Electron Storage Ring (ESR) and collided. Extraction out of the RCS is complicated by limited space and the nominal beam pipe aperture, while injection into the ESR is complicated due to the limitation of kicker strength, so that the kickers will not impact the proton beam in the adjacent Hadron Storage Ring (HSR); additionally, the ESR kickers must also provide enough kick to the stored bunch for the swap-out scheme. This paper covers the injection into and extraction out of the RCS, as well as injection into the ESR, detailing layout, optics, and anticipated parameters of the septa and different kickers.

Speaker: Dr Todd Satogata (Thomas Jefferson National Accelerator Facility)

WEP1374_edited_version.pdf

16:00 Extrapolated optics measurement from BPM to instrumentation in LHC commissioning

Segment-by-Segment (SbS) analysis is employed in accelerators for the determination of lattice errors and corrections, by identifying deviations between optics functions propagated through a modelled lattice segment and measured values. For the Large Hadron Collider (LHC), this method is routinely used during optics commissioning for the compensation of strong local errors in the experimental insertions and arcs. Beyond the determination of corrections however, the SbS approach is also of interest to propagate optics functions measured at the BPMs, to key instrumentation in other locations in the ring, for example to improve emittance measurements by providing more accurate estimates of the optics functions at relevant devices. The SbS tools used in the LHC have been further developed to support the propagation of measurement to lattice target locations distinct from the BPMs, leading to new possible applications. In this paper the analysis methods and results from recent LHC commissioning are presented.

Speaker: Mattia Stefanelli (European Organization for Nuclear Research, National Institute for Subatomic Physics)

WEP5072_edited_version.pdf

16:00 Fast and accurate accelerator modelling with FLUKA CAD geometry workflow

Accurate geometric representation is essential in accelerator beam-matter interaction Monte-Carlo simulations, yet conventional Constructive Solid Geometry (CSG) modeling of beamline elements or tunnels remains time-consuming and error-prone. Recent FLUKA developments offer a robust alternative to manual CSG implementation by introducing a CAD-based (Computer Aided Design) workflow. The new approach supports CAE (Computer Aided Engineering) volumetric meshes and the direct import of meshes generated in Gmsh, Ansys, or Abaqus. This workflow is expected to accelerate model development, particularly for complex geometries. Benchmark comparisons will be presented between FLUKA conventional CSG geometries, FLUKA CAE-mesh geometries, and an independent development carried out in Geant4 to support CAD surface meshes: the results demonstrate that while CAE meshes introduce a modest performance penalty, they provide substantial gains in accuracy, maintainability, and interoperability across design and simulation environments.

Speaker: Helene Guerin (European Organization for Nuclear Research)

WEP5132_edited_version.pdf

16:00 Feasibility of Antiproton Accumulation in the RESR with Barrier Bucket and Stochastic Cooling

The barrier bucket antiproton accumulation scheme is investigated for the RESR ring, which is proposed to be constructed using the existing COSY ring magnets. In the baseline design, RESR serves as an intermediate storage and accumulation ring for antiprotons precooled in the Collector Ring (CR) by stochastic cooling. The main objective is the accumulation of up to 10¹¹ antiprotons within a few hours, enabling high-intensity antiproton beams for further experiments in the (High Energy Storage Ring) (HESR).
Since the magnetic aperture of the COSY ring components is too small to accommodate conventional longitudinal stochastic stacking, the application of the barrier bucket accumulation method combined with stochastic cooling is proposed as an alternative. In this scheme, batches of 10⁸ stochastically precooled antiprotons, delivered by the CR every 10 seconds at a beam energy of 3 GeV, are accumulated in the longitudinal phase space using RF barrier buckets. After sufficient accumulation, the stored antiprotons are transferred to the HESR for subsequent acceleration or deceleration according to experimental requirements. This approach allows the reuse of existing accelerator components, reducing overall construction costs while maintaining the capability for efficient high-intensity antiproton accumulation. The feasibility and expected performance of the proposed barrier bucket accumulation scheme are discussed based on numerical simulations and beam dynamics considerations.

Speaker: Oleksiy Dolinskyy (GSI Helmholtz Centre for Heavy Ion Research)

WEP5013_edited_version.pdf

16:00 Feasibility of Non-invasive OSR Diagnostics in the AWAKE run-2C Injection Region

AWAKE is CERN's proton-driven plasma wakefield acceleration experiment, currently advancing toward Run-2c to demonstrate the higher energy acceleration of electrons while maintaining the beam quality. A second electron beam (of 150 MeV energy), produced in a newly installed electron source, will be injected and accelerated to several GeVs while aiming to keep good emittance. Diagnostics are being upgraded for this geometrically constrained injection-region to enable single-shot characterization of that beam, among which this contribution evaluates the feasibility of optical synchrotron radiation (OSR) as a non-invasive real-time mean.
OSR can provide shot-by-shot transverse position and profile information without disrupting beam delivery, critical for benchmarking beam-alignment and quality check. The prompt, non-invasive nature also makes it a candidate for future virtual diagnostic implementations, where online beam profiles could inform predictive models or feedback correction schemes.
For performance optimizations the expected OSR photon flux, photon statistics, projected image quality are computed with realistic imaging optics and detector quantum efficiency. Results demonstrate that sufficient OSR signal can be extracted through this compact optical chain to achieve meaningful single-shot transverse profile measurements.

Speaker: Debdeep Ghosal (University of Liverpool)

WEP6089_edited_version.pdf

16:00 FEL Power Profile Predictions with Image-Based Machine Learning at FLASH

Accelerator operators and beamline users can highly benefit from accurate and efficient measurements of FEL (free-electron laser) pulse power profiles. The use of machine learning to predict such profiles is an area of rapid development in the field. This work presents recent measurements and tests at the FLASH FEL at DESY of an image-based machine learning application developed to facilitate online FEL power profile reconstruction. The reconstruction has been performed using machine learning predictions of the longitudinal phase-space (LPS) of electron beams unaffected by the FEL process, originally measured using a transverse deflecting structure. The predictions were used in combination with longitudinal measurements of the LPS of the electron beam after lasing, which does not interfere with delivery to users, to reconstruct the FEL pulse. The results of the reconstruction process have been validated by comparison with a reference method which does not rely on machine learning.

Speaker: Johan Lundquist (MAX IV Laboratory, Lund University)

WEP6014_edited_version.pdf

16:00 Final Focus Systems at 550 and 1500 GeV

The Final Focus System (FFS) results for CLIC at 1.5 TeV have thus far been estimated using a 3 TeV system operated at reduced energy. Here, we present a dedicated design for the 1.5 TeV stage, where we exploit reduced radiation effects to allow stronger dispersion and weaker chromaticity-correcting sextupoles, thereby mitigating beam transport nonlinearities. The resulting design is 220 m shorter and offers a 50% luminosity gain. The performance of both normal-conducting and superconducting beams at 550 GeV are evaluated using the CLIC FFS, addressing the goals defined by the CLIC and Linear Collider Facility at CERN inputs to the European Strategy for Particle Physics Update.

Speaker: Lewis Kennedy (European Organization for Nuclear Research, John Adams Institute for Accelerator Science, University of Oxford)

WEP5047_edited_version.pdf

16:00 FIRST EXPERIMENTAL DEMONSTRATION OF USING A CRAB-CROSSING COLLISION SCHEME FOR EFFICIENT LASER-TO-ION BEAM INTERACTION

Lasers are used in many applications with H⁻ beams, including laser charge exchange, laser wire scanners, and laser temporal pulse patterning. In these applications, the H⁻ beams exhibit a wide range of bunch lengths that depend on the focusing of the RF cavities, the energy spread of the beam, and space charge forces. Achieving the required laser pulse length for complete overlap with the H⁻ beam can be challenging in scenarios where available laser power is constrained. A crab-crossing scheme was proposed to achieve efficient overlap of a short laser pulse with an arbitrarily long H⁻ beam pulse. This presentation reports the first experimental demonstration of this technique, which increases the efficiency of laser-to-ion beam interaction in a laser stripping experiment at SNS by 50%.

Speaker: Alexander Aleksandrov (Oak Ridge National Laboratory)

WEV4302_edited_version.pdf

16:00 First Measurements of the Transient Electrical Near-Field of Electron Bunches in the FLUTE In-Air Section

The Ferninfrarot Linac- und Test-Experiment (FLUTE) at the Karlsruhe Institute of Technology (KIT) is a compact linac test facility providing sub-picosecond to femtosecond short electron bunches with energies up to several tens of MeV. The transient electric near-field of such bunches is relevant for understanding coherent THz emission and for developing compact field-sensitive beam diagnostics. Here, we present first electro-optical measurements of bunch-induced near-field signals in the FLUTE in-air section using a photonic-integrated Mach-Zehnder-interferometer sensor placed close to the beam axis. The measured delay-dependent response shows features consistent with electro-optical detection of the transient electric near field of the bunch. Our results establish a basis for future spatially resolved measurements with varying accelerator parameters.

Speaker: Stefan Funkner (Karlsruhe Institute of Technology)

WEP6049_edited_version.pdf

16:00 First Parallel Arc Quadrupole Beam-Based Alignment using K-Modulation at LHC

The Large Hadron Collider (LHC) is a circular hadron collider for high-energy particle physics. Off-centre beam passage through quadrupoles results in additional deflection, which needs to be compensated by corrector magnets. Beam-based alignment is an option to reduce the beam offset in the quadrupoles by using an estimate for the Beam Position Monitor (BPM) to magnet offset as reference for the orbit feedback. The in-series powered LHC arc quadrupoles do not allow the variation of the quadrupole strength of individual magnets, this requires a parallel approach for the beam-based alignment. Various approaches based on k-modulation for parallel beam-based alignment are considered.

Speaker: Christian Goffing (European Organization for Nuclear Research)

WEP5035_edited_version.pdf

16:00 FLUKA studies of spent beam extraction in the muon collider target system

A multi-TeV muon collider relies on a particle souce based on a megawatt-scale proton beam striking a target to produce muons and pions immersed in a 20 T solenoid, followed by a tapering region and a chicane in solenoid magnets to capture and guide the pions and then muons toward cooling sections. For the characteristic target lengths that maximise the pion yield, a fraction of the proton beam is expected to exit the target without inelastic collisions. These protons carry high power in a highly collimated phase space, requiring a dedicated extraction scheme downstream of the target. Within the International Muon Collider Collaboration, simulations have been performed with the FLUKA Monte Carlo code to evaluate potential extraction strategies in both the target region and the downstream chicane. These studies assess power deposition, dose, and atomic displacements in the target and downstream areas and analyse shielding options to protect sensitive elements. The work defines the main radiation-driven design constraints and compares the main benefits and shortcomings of each option.

Speaker: Helene Guerin (European Organization for Nuclear Research)

16:00 FLUKA-Based Optimization of Pion Production for a Muon Collider Demonstrator

This study uses FLUKA simulations to investigate pion production from proton interactions with a graphite target for muon collider applications. A 40 cm target is struck with 0.8 GeV and 8 GeV/c proton beams, and pion yields are evaluated in terms of angular and energy distributions. The dependence of pion yield on target length is also examined, showing saturation near one interaction length for the 0.8 GeV beam, and saturation near two interaction lengths for the 8 GeV/c beam due to secondary interactions. In addition to total production, a subset of “acceptable” pions is defined based on capture constraints (kinetic energy <400 MeV, forward-going, and escaping the target). The results show that while the 8 GeV/c beam produces higher overall yields, the 0.8 GeV beam provides a larger fraction of pions within the desired constraints. Charge asymmetry is also observed in pion production, with implications for muon beam balance and collider luminosity.

Speaker: Ruaa Alharthy (University of Wisconsin–Madison)

WEP1347_edited_version.pdf

16:00 From Manual Checks to Automated Workflows: A Commissioning Tool for GSI and FAIR

Commissioning of accelerator facilities involves many repetitive hardware tests and verification steps. At GSI, the large number of devices already makes it difficult to check all components manually after each shutdown, a challenge that will grow further during FAIR commissioning. To reduce operator workload and ensure consistent procedures, an automation tool has been developed that executes predefined tasks and test steps sequentially. Initially introduced for hardware testing, it is now regularly used during post-shutdown commissioning of the GSI accelerator chain. The tool provides configurable test procedures, automated execution across multiple subsystems, and integrated reporting. A graphical interface allows operators to select tasks and monitor progress. Recent developments improved robustness, device coverage, and integration with the GSI control system. For FAIR, the tool is being extended to support High Energy Beam Transport (HEBT) commissioning and is planned to be used in preparation for the FAIR First Beam activities in 2026. This contribution summarizes current capabilities, operational experience, and future developments toward automated commissioning workflows.

Speaker: Oksana Geithner (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Generic Python Algorithm Plugin for the EPICS Area Detector Framework

Area Detector is widely used in accelerator and observatory control systems to build data processing pipelines for images and waveforms, but adding new processing stages normally requires specialized C++ development. This slows prototyping and limits access to modern analysis tools that are predominantly available in Python. We present a new Area Detector plugin that executes user-defined Python algorithms directly on acquired images and their metadata. The plugin integrates advanced scientific libraries and machine learning toolkits, supports GPU acceleration, and enables parallel execution through multi-stage pipelines or Python multiprocessing. Algorithms can be updated without recompiling the IOC, allowing rapid iteration during operations. An automatically generated GUI exposes configurable parameters to operators. The approach is being evaluated on ESA’s NEOSTED telescope system, where Python-based routines are used for telescope autofocusing.

Speaker: Tilen Zagar (Cosylab)

WEP6165_edited_version.pdf

16:00 Global Momentum Compensation Scheme Enabled by Sequential Inference in Large-Scale Linacs

A fundamental challenge in large-scale accelerator operation is to infer internal machine states from limited monitoring. In the J-PARC linac, errors in RF cavities lead to momentum drifts observable through beam phase monitors. Although the number and placement of monitors satisfy the solvability condition, the cumulative and sequentially coupled nonlinear nature of beam dynamics makes the inverse problem numerically ill-conditioned.
Our initial machine-learning study demonstrated that a multilayer perceptron can accurately model the forward mapping from cavity errors to observed phases. However, the inverse model, which predicts cavity errors from monitor signals, failed under the non-redundant condition where each cavity was followed by only one phase probe. In contrast, when at least two probes were available (redundant case), the inverse prediction became accurate. This brought to light a fundamental limitation: what appeared to be a dependence on monitor redundancy was, in fact, a consequence of the model’s limited capacity to represent cumulative dependencies and of the insufficient information content in the training data.
We reformulated the problem within an encoder/decoder framework, which treats the accelerator as a causal sequence of coupled elements. The inverse prediction succeeded in the non-redundant case. This reveals that physical irreversibility can be effectively mitigated when the model captures the hidden correlations underlying the sequential process.

Speaker: Yong Liu (High Energy Accelerator Research Organization)

16:00 Global start-to-end optimization with Bayesian Optimization

Controlling the beam longitudinal phase space (LPS) distribution is crucial for advanced free-electron laser operation modes. At the European XFEL, this task is particularly challenging due to the complex compression scheme, which includes three bunch compressors. We present an approach based on Bayesian optimisation that simplifies the search for compression configurations yielding current profiles with desirable features, such as a flat top or a pronounced spike at either the head or the tail of the bunch. Moreover, this method can also be applied to tune the RF parameters in start-to-end simulations to achieve better agreement with measured longitudinal phase space profiles.

Speaker: Stuart Walker (Deutsches Elektronen-Synchrotron DESY)

WEP6157_edited_version.pdf

16:00 Gradient-based laser control for end-to-end photoinjector emittance optimization at EuXFEL

Achieving low emittance at the photoinjector is essential for meeting the performance targets of the European XFEL, particularly for high photon energies and future high-duty-cycle operation. Both the temporal structure of the drive-laser pulse and the RF-gun settings contribute significantly to the final beam quality, yet their optimization is complicated by strong nonlinearities in the laser system and complex gun response. We have developed a differentiable, physics-based model of NEPAL, the photoinjector laser of EuXFEL, that enables gradient-driven optimization of the temporal UV pulse shape. The model captures the relevant nonlinearities of the optical chain and allows direct optimization of spectral amplitude and phase to obtain target UV profiles at the photocathode. In parallel, a machine-learning surrogate model is being implemented to optimize the RF-gun operating parameters. Together, these tools provide an end-to-end control framework for emittance reduction at EuXFEL. Initial results demonstrate that the differentiable model enables accurate temporal UV pulse shaping at EuXFEL. Work is ongoing to integrate this approach with ML-assisted gun optimization within the proposed end-to-end control framework.

Speaker: Denis Ilia (Deutsches Elektronen-Synchrotron DESY, Universität Hamburg)

WEP6006_edited_version.pdf

16:00 GSI Operation Statistics in the FAIR Construction Phase (2012 - 2025): Trends, Failures and Lessons Learned

We present operational statistics for the GSI accelerator complex during the FAIR construction phase from 2012 to 2025, covering UNILAC, SIS18, ESR, HEST and CRYRING@ESR. The analysis is based on beam-time schedules, availability monitoring, and fault annotations from the Operator Logbook (OLOG). During the last five years, failure entries were systematically reviewed and reclassified to ensure consistent data quality and enable reliable long-term trend evaluation. The main performance indicator discussed is accelerator availability, determined from scheduled operation periods and fault-related downtimes. The evaluated data were used as a quantitative input in the recent POF-5 evaluation process (2028-2034), where they clearly supported refurbishment and consolidation needs at GSI. A technical roadmap was established this year to prioritize these measures according to their impact on stable beam delivery towards FAIR accelerators.

Speaker: Oksana Geithner (GSI Helmholtz Centre for Heavy Ion Research)

WEP6127_edited_version.pdf

16:00 Hadron beam heating in collisions with electron beam

Hadrons collision with electron beam in ring-ring collider differ from those in hadron collider. The main difference is that transverse position of electrons is changing at each turn by quantum fluctuations of synchrotron radiation. This random changes in position result in local density modulation and in additional transverse diffusion and emittance growth of the hadron beam. In this paper we present the model for simulating these effects and results of computer simulations. We present numerical results for the case of future electron-ion collider at BNL.

Speaker: Vladimir Litvinenko (Stony Brook University)

16:00 Hadron Storage Ring Spin Rotators & Spin Tune Compensation

The Electron Ion Collider (EIC) calls for collisions of longitudinally polarized
protons and helium-3 on electrons. The polarized hadron beams will be accel-
erated and stored in the Hadron Storage Ring (HSR). To achieve longitudinal
polarization at the interaction point (IP), spin rotators are placed on either side
of the IP at 35.28 and -61.35 mrad. Due to the asymmetry of the rotators, their
ramping and use will result in a shift of νs from 1/2. The HSR has six snakes
that can be used to compensate for the ∆νs. The planned storage energies for
protons are 41, 100, and 275 GeV, and for helium-3 are 41, 100, and 183 GeV/u.
The updated rotator currents at each of these energies is provided, in addition
to the ∆νs and the compensation requirements of the snakes.

Speaker: Kiel Hock (Brookhaven National Laboratory)

WEP1307_edited_version.pdf

16:00 Halo cleaning and collimator optimization at PERLE

PERLE (Powerful Energy Recovery Linac for Experiments) is a multi-turn, high-current energy-recovery linac under development at IJCLab, designed to operate at 20~mA and 250~MeV.
To limit beam-induced losses in downstream superconducting sections, halo particles must be intercepted at low energy.
In this work, halo cleaning in the merger is studied using a 6D particle distribution obtained after the booster stage, at 7~MeV.
The beam phase-space evolution is analyzed to identify optimal locations for one or two collimators.
Particle tracking simulations performed with the Bmad code are used to validate the collimation strategy and quantify its efficiency.
Despite the low dispersion in the merger, correlations between transverse and off-momentum halo enable partial removal of off-momentum particles.
The sensitivity of the collimation efficiency to booster cavity misalignments is also investigated.

Speaker: Arnaud CIEPLAK (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

WEP5064_edited_version.pdf

16:00 Heavy Ion Beam Production on the Modernized DECRIS-3 ECR-source at the DC-60 Cyclotron

The electron cyclotron resonance (ECR) ion source DECRIS-3 of the DC-60 cyclotron* is one of the key components of the accelerator complex. It can operate both as an injector of heavy ions into the cyclotron to produce high-energy ion beams, and in standalone mode, providing low-energy beams. The ECR-source, as part of the DC-60 heavy-ion accelerator, was commissioned in 2006.
To ensure the successful implementation of the scientific and technical programs carried out on the accelerator in 2025, a modernization of the ion source was completed. The main goal of the upgrade was to increase the beam intensity and improve the operational stability of the DECRIS-3 source. For this purpose, a technical specification was developed that included the complete replacement of the following systems:
1. Magnetic system: hexapole, front and rear plugs, and additional iron elements.
2. Plasma chamber.
3. Microwave injection and working-substance feed assembly (short-circuit plunger).
4. Turbo-pump insulator mounting unit.
5. Vacuum-volume components.

The source employs three methods of ion production: ionization from gaseous media, heating of materials using a micro-oven, and evaporation of metal-organic compounds.
The modernization of the DECRIS-3 ECR-source has significantly improved the beam current of highly charged ions. A brief overview of the ongoing scientific work and technical cooperation based on the DC-60 facility was also presented.

Speaker: Igor Ivanov (Institute of Nuclear Physics)

16:00 High Level Software and Automation for Measurements using the Transverse Deflecting Structures at the EuXFEL

Longitudinal phase space (LPS) measurements at the EuXFEL are reliant on several hardware and software subsystems. Previously, LPS measurements have required explicit manual operation of many of these subsystems by a specially-trained operator, which could be both time consuming and error prone. In order to make these measurements routine, fast, and simple enough that non-specialist operators can independently measure the LPS, we have written a high-level application that encapsulates and automates the control of these subsystems as well as the subsequent data analysis. In this paper we describe this application, its performance and use at the EuXFEL.

Speaker: Stuart Walker (Deutsches Elektronen-Synchrotron DESY)

16:00 High power BLA test update and path forward for EIC BLA

Electron-Ion Collider (EIC) is a next generation particle accelerator to be built at Brookhaven National Laboratory, in partnership with Thomas Jefferson National Accelerator Facility. In EIC Cryomodules, there are SiC BLA for HOM absorbing. The power handling test was carried out and a second BLA high power test will be completed in early 2026. This paper presents the latest results of high power test on BLA. A path forward for EIC BLAs production will be presented as well.

Speakers: Silvia Verdu-Andres (Brookhaven National Laboratory), Wencan Xu (Brookhaven National Laboratory)

16:00 HIGH POWER FPC PROGRESS FOR EIC ESR CAVITIES

Electron-Ion Collider (EIC) is a next generation particle accelerator to be built at Brookhaven National Laboratory, in partnership with Thomas Jefferson National Accelerator Facility. In Electron Storage Ring (ESR), 18 single-cell 591 MHz SRF cavities are required to compensate for up to 10 MW energy loss due to synchronic radiation. Two high power FPCs for each cavity are used to deliver up to 800 kW power to the beam. The high power FPC were designed and manufactured. The FPC prototypes will be ready for high power test around mid-2026. This paper presents the latest development of FPC prototyping and path forward for FPC conditioning, including application of AI/machine learning for conditioning process.

Speakers: Silvia Verdu-Andres (Brookhaven National Laboratory), Wencan Xu (Brookhaven National Laboratory)

16:00 High-Average-Current, High-Brightness HVDC Electron Gun development for EIC Hadron Cooling

The hadron cooler is an essential system for achieving high luminosity in the Electron-Ion Collider (EIC). The required electron source parameters exceed the current state of the art. We are conducting an electron-source R&D program aimed at producing an average current above 75 mA with bunch charges of 1–3 nC.
This proceeding outlines the high-voltage design of a DC gun operating at 500 kV, with conditioning capability up to 600 kV. The design incorporates several unique features, including an inverted ceramic insulator at this voltage level, active cathode cooling, and large single-crystal multi-alkali photocathodes grown on silicon carbide substrates. This paper presents recent progress on gun construction, commissioning plans, and preliminary major components test results.

Speaker: Erdong Wang (Brookhaven National Laboratory)

WEP1352_edited_version.pdf

16:00 High-Dimensional Bayesian Optimization for Sparse Objectives: an Application for Automated Beam Commissioning in the Low Energy Ion Ring at CERN

Recent advances in high-dimensional Bayesian Optimization have opened the door to new tools for beam commissioning. At the CERN Low Energy Ion Ring (LEIR), several tuning challenges arise from the complex parameter space governing beam transfer and accumulation dynamics. In this paper we benchmark several state-of-the-art High Dimensional Bayesian Optimization methods to optimize the transfer from Linac3 to LEIR and maximize the accumulated beam inside the ring. We evaluate algorithms based on different strategies: trust region approaches (TuRBO), sparse axis-aligned subspace priors (SAASBO), nested embeddings for mixed spaces (Bounce), and length-scale-adapted priors in regular Bayesian Optimization. Our results demonstrate the relative strengths of each method in the context of particle accelerator optimization, where sample efficiency is critical, the objective function exhibits sparsity in relevant dimensions, and the parameter space contains both local and global structures. The benchmarking provides practical insights for selecting appropriate algorithms for beam commissioning tasks, considering factors such as convergence speed, computational overhead, and robustness to noisy observations.

Speaker: Borja Rodriguez Mateos (European Organization for Nuclear Research)

WEP6018_edited_version.pdf

16:00 High-Gradient Booster Linac for Multi-GeV Proton Radiography at LANSCE

Increasing energy of proton beam at the Los Alamos Neutron Science Center (LANSCE) from 800 MeV to 3-5 GeV will improve radiography resolution ten-fold. This energy boost can be achieved with a compact cost-effective linac based on normal conducting high-gradient (HG) RF accelerating structures operating at liquid nitrogen temperatures (cryo-cooled). Such an HG booster is feasible for proton radiography (pRad), which requires short beam pulses at very low duty. The pRad booster starts with a short L-band section to capture and compress the 800-MeV proton beam from the existing linac. The main HG linac will be based on S- and C-band cavities. An L-band de-buncher at the booster end can reduce the beam energy spread if needed for pRad experiments. We are developing proton cryo-cooled HG standing-wave structures with distributed RF coupling for the booster. Prototype cavity structures at S- and C-band are designed and will be tested cryo-cooled to measure breakdowns at high gradients. The booster linac beam dynamics design will also be presented.

Speaker: Sergey Kurennoy (Los Alamos National Laboratory)

WEP4320_edited_version.pdf

16:00 High-intensity Beam Accumulator Ring for Electron-Ion Collider

The Beam Accumulator Ring (BAR) is part of the Electron-Ion Collider (EIC) injector complex at Brookhaven National Laboratory. It is designed to accumulate a polarized 750 MeV electron beam up to a single-bunch charge of 28 nC for injection into the Rapid Cycling Synchrotron (RCS). A compact double-bend achromat lattice is based on the NSLS VUV ring. The BAR design incorporates well-proven magnet, vacuum, RF, beam diagnostics, and control technologies. Comprehensive studies of injection and extraction schemes, error correction, and collective effects demonstrate robust beam accumulation. With the bunch shortening by RF modulation to mitigate the bunch lengthening caused by the microwave instability, all beam parameters at extraction meet the specifications. The preliminary design validates BAR performance goals and establishes readiness for integration into the EIC injector chain.

Speaker: Ihar Lobach (Brookhaven National Laboratory)

WEP1324_edited_version.pdf

16:00 High-Level Applications for LINAC Commissioning at ELI-NP

The ELI-NP (Extreme Light Infrastructure – Nuclear Physics) Gamma-ray Beam Source (ELI-GBS), currently under construction, employs an 800 MeV linear accelerator (LINAC) to generate high-brightness gamma rays through laser–electron interactions. Its control system is designed as a distributed, EPICS-based architecture, where engineering-level control is provided for devices such as LLRF, modulators, magnets, profile monitors, and current monitors.
A set of high-level application tools is required for LINAC beam commissioning, tuning, and the measurement of key accelerator parameters. To meet the beam diagnostic capabilities and performance requirements of the commissioning process, we have developed Python-based high-level application software to support essential commissioning tasks, including gun phase scans, emittance measurements, and beam energy measurements. The software uses the pyepics package to interface with engineering-level device IOCs.
To support visualization and offline simulation, a set of Python soft IOCs has also been implemented, enabling realistic emulation of device behavior and data acquisition workflows. The online measurement capabilities of the system will be validated during the upcoming RF Gun commissioning and the subsequent LINAC commissioning phases.

Speaker: Guangling Chen (Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering)

WEP5127_edited_version.pdf

16:00 High-Precision Three-Axis Teslameter for Superconducting Magnet Alignment of a Gyrotron at the Swiss Plasma Center

This paper presents the design of a high-precision three-axis Teslameter and its application for magnetic field alignment of a superconducting magnet prior to gyrotron installation, at the Swiss Plasma Center. The instrument integrates an advanced 3-axis Hall sensor with an ultra-compact sensitive volume of 0.10×0.01×0.10 mm³, enabling true point-like vector field measurements. We describe the sensor architecture, Teslameter performance, and calibration procedures, including precise orthogonality characterization. The Teslameter achieves DC accuracy better than 100 ppm and 1 µT resolution.
The system was employed to verify and optimize magnetic field alignment for high-power gyrotrons, vacuum electronic devices generating sub-terahertz radiation via the cyclotron maser instability. Efficient operation of these devices requires that the magnetic field axis remain confined within a cylinder of 0.15 mm diameter over a 700 mm length to maintain correct electron–field interaction. Using the Teslameter, the magnetic field was mapped with high accuracy, enabling fine realignment of the superconducting magnet and ensuring the electron beam coincides with the electric field maximum of the transverse electric (TE) mode. This methodology guarantees optimal gyrotron performance, contributing to reliable and efficient operation of Electron Cyclotron Resonance Heating and Current Drive systems in magnetic confinement fusion research.

Speaker: Dr Dragana Popovic Renella (SENIS AG)

WEP6121_edited_version.pdf

16:00 Higher Order Analysis for the Wakefields of a Single-plate Corrugated Structure

Wakefields induced during the interaction of beam-environment could cause strong distortion of electron beam longitudinal and transverse phase space. Numerical modeling of the effect often relies on approximating the externally obtained point-charge wake with second-order Taylor expansion and convolving with beam distribution during particle tracking. In this contribution, we extend the method to the third order. We apply the method to the case of a transversely tilted beam traveling through a corrugated wakefield structure.

Speaker: Dr Weilun Qin (Institute of High Energy Physics, Chinese Academy of Sciences)

WEP2601_edited_version.pdf

16:00 Highlights of Spill Optimization System Usage at GSI and Progress of Controls Integration

At the GSI SIS18 synchrotron, the Spill Optimization System (SOS) has been established as a key tool to improve spill quality during resonant slow extraction. During the 2025 beam times, the SOS was routinely used with the radio frequency knock-out (RF-KO) method for several experimental campaigns, enabling improved spill stability and more efficient beam delivery to users under various operational conditions. The experience gained during these runs has also guided the ongoing integration of the SOS into the FAIR control system environment. This integration enables time-multiplexed operation of the system for multiple experiments running in parallel, leading to more efficient operation. It also aims to streamline the setup and monitoring of slow extracted spills through tighter coupling with accelerator controls and unified human and machine interfaces. This contribution summarizes the operational highlights from the 2025 beam times and discusses observed improvements in spill stability and beam usability for the experiments. In addition, the current status and outlook of the full control system integration efforts are presented.

Speaker: Philipp Niedermayer (GSI Helmholtz Centre for Heavy Ion Research)

WEP6111_edited_version.pdf

16:00 HL-LHC magnets field quality: Current situation, strategies and mitigation measures

The production of the new superconducting magnets for the luminosity upgrade of the LHC is in full swing. The performance of the magnets is probed by means of detailed magnetic measurements of the transfer function and field quality of the various families of magnets, i.e. triplet quadrupoles and separation and recombination dipoles. In this paper, the current situation in terms of magnetic properties is presented and reviewed in detail. Furthermore, dedicated beam dynamics simulations to address the possible issues for the various families of magnets are presented.

Speaker: Massimo Giovannozzi (European Organization for Nuclear Research)

WEP5069_edited_version.pdf

16:00 HOM study of the PERLE’s booster cavity

The injector for the PERLE ERL in construction at IJCLab is based on a booster containing 4 superconducting cavities to reach 7 MeV for 20 mA of cw current. The cavities are single cell at 801.58 MHz. Due to the high average current, issues of beam break-up and power dissipation induced by the higher order modes of the cavities are a matter of concern. In this paper, we will report on the systematic survey of the HOM thanks to CST simulations up to 8 GHz. An analysis of their harmfulness as a function of the current spectrum will be shown.

Speaker: Raphaël Roux (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

WEP5089_edited_version.pdf

16:00 IFMIF-DONES Beam on Target Diagnostics based on Optical Methods: OTR and Fluorescence

The IFMIF-DONES facility located at Escúzar in Spain will consist of an accelerator delivering 125 mA of 40 MeV deuterons onto a liquid lithium target. The beam profile at the target will have a rectangular footprint with two side peaks to satisfy the irradiation requirements. The environment conditions are characterized by a high radiation background and the presence of lithium vapor. Additionally, deuteron scattering with residual gas and secondary-electron production occur. To measure the footprint under these conditions optical methods are designed based either on measuring Optical Transition Radiation (OTR) of the beam passing through the liquid lithium or on the Beam Induced Fluorescence (BIF) of the residual gas in the proximity of the liquid lithium. Both alternatives have its advantages and drawbacks. In this paper it is described the pros and cons of both alternatives. Furthermore, an experiment to better characterise the OTR response in liquid lithium is also presented.

Speaker: Jorge Herranz (IFMIF-DONES España, Universidad de Granada)

WEP6074_edited_version.pdf

16:00 IFMIF-DONES control systems and testing platform

IFMIF-DONES is an accelerator-based neutron source under construction in Granada, Spain. Its goal is to generate an intense and continuous flux of fusion-like neutrons to qualify the materials to be placed in nuclear-fusion reactors. Meeting its ambitious availability targets imposes stringent reliability requirements on all components, particularly transversal systems such as Control Systems.

To address this, a dedicated testing platform is being developed to validate architectural and technological choices. Key aspects under evaluation include the EPICS IOC deployment model (container-based) and orchestration solution (currently evaluating Proxmox HA, Docker Swarm and Kubernetes). It is also envisaged to integrate the existing DONES prototypes into the testing platform.

The testing platform will deliver value across all project phases by reducing risks, improving consistency, and enhancing readiness. In early stages, it supports operation of the DONES prototypes and minimizes risks by validating design choices. During development and commissioning, it will foster standardization through shared tools and procedures, easing integration and enabling early operator training. In operation and maintenance, it will uphold accessibility and usability standards, as well as long-term reliability and maintainability.

This contribution will present the proposed architecture of the IFMIF-DONES control systems and report on the design and current progress of the testing platform.

Speaker: Manuel J. Gutiérrez (IFMIF-DONES España)

WEP6103_edited_version.pdf

16:00 Impact of a quasi-resonant AC dipole excitation on transverse beam splitting

For multi-turn extraction at the CERN Proton Synchrotron, the beam is transversally split into five separate beamlets. It has been shown that an AC dipole excitation effectively controls the characteristics of these beamlets. For this purpose, the AC dipole is set in resonance with the horizontal betatron tune while the horizontal tune crosses the 4th-order resonance, creating a double-resonance condition, i.e. the simultaneous resonance between the horizontal tune and the AC dipole excitation. This increases the fraction of particles that are moved from the core to the islands. Further studies have revealed that shifting the AC dipole tune slightly, thereby breaking the double-resonance condition, distributes the beam more evenly across the beamlets. This paper examines this phenomenon by establishing a Hamiltonian model for a system with such a quasi-resonant AC dipole and studying it with numerical simulations.

Speaker: Oleksandr Naumenko (European Organization for Nuclear Research)

WEP5077_edited_version.pdf

16:00 Impact of Landau Octupoles on the Transverse Beam Halo Distribution in the LHC

The distribution of beam halo particles in the Large Hadron Collider (LHC) is affected by non-linear fields, in particular by the Landau octupoles used to provide tune spread for beam stabilization. These elements introduce amplitude-dependent tune shifts that deform the transverse phase-space and may alter the steady-state halo population. In this study, tracking simulations are performed to quantify the expected halo distributions for different octupole settings, without beam-beam effect, and to investigate whether such non-linear effects could contribute to the variations observed in different measurements. The analysis aims to provide a first quantitative assessment of the potential correlation between octupole-induced non-linearities and the observed beam halo characteristics in the LHC.

Speaker: Chiara Maccani (European Organization for Nuclear Research)

WEP5117_edited_version.pdf

16:00 Impact of Power Supply Ripple on Beam Dynamics in the FCC-ee

The electron–positron Future Circular Collider (FCC-ee)
is a proposed lepton collider for high-energy particle physics
as a possible successor of the Large Hadron Collider (LHC).
The extremely tight emittance and beam stability require-
ments of the FCC-ee make the control of time-dependent
magnetic field variations critical. Power supply ripples in-
troduce fluctuations in the magnetic field of accelerator mag-
nets, which translate into turn-by-turn orbit and tune modu-
lations, potentially leading to emittance growth and beam
degradation. In this context, single-particle tracking simu-
lations are used within the Xsuite simulation framework to
assess the impact of such noise on beam quality in view of
defining power converter specifications.

Speaker: Anna Radoslavova (European Organization for Nuclear Research)

16:00 Impact of Wiggler Field Profiles on Key Beam Parameters in the STCF

The Super Tau-Charm Facility (STCF), a next-generation high-luminosity frontier collider, adopts a large crossing angle with the Crab-Waist scheme to enhanced collision luminosity. The center-of-mass energy range of STCF is 2-7 GeV, and the designed collision luminosity will exceed $0.5 \times 10^{-35} \, \text{cm}^{-2} \text{s}^{-1}$. The STCF’s collider rings are two high-current, low-emittance electron and positron storage rings operating over a wide energy range. However, synchrotron radiation damping from lattice alone is inadequate to achieve the desired short damping time, low horizontal emittance, and relatively high beam energy spread. To address this, the damping wigglers are incorporated into the rings to enhance damping effects.
This study finds that the longitudinal magnetic field distribution $B_{y}(s)$ in practical damping wigglers often deviates from the ideal sinusoidal curve. Particularly for damping wigglers with large period lengths, the field profile near the peak approaches a flat-top shape, which differs significantly from a sinusoidal curve. To better represent such field distributions, a trapezoidal field model was developed with the definition of a rectangularity parameter $k$. Based on this model, analytical formulas for synchrotron radiation integrals and beam parameters under the trapezoidal field approximation have been derived, enabling further parameter optimization of the damping wigglers in the STCF collider rings.

Speaker: Hangzhou Li (University of Science and Technology of China)

16:00 Impedance analysis for the EIC Beam Accumulator Ring

The Beam Accumulator Ring (BAR) in the EIC injector chain accumulates charge from multiple linac pulses to provide the high-intensity polarized electron beam required for ESR injection. At the design single-bunch charge, beam–impedance effects become a key performance and stability limit, so initial broadband-resonator estimates must be refined with a realistic impedance budget. We use the 3D EM solver GdfidL to compute the longitudinal and transverse geometric impedances of the main vacuum components and combine them with the resistive-wall contribution in a ring-wide model.

Speaker: Victor Smaluk (Brookhaven National Laboratory)

WEP1325_edited_version.pdf

16:00 Implications of Degenerate Mode Mixing in UK XFEL SC Cavities

The UK XFEL (United Kingdom X-ray Free Electron
Laser) is a proposed accelerator facility that will use pre-
dominantly superconducting RF structures to accelerate and
manipulate the transiting electron bunches. Deviations from
design longitudinal length of these Niobium RF cavities,
or cells within, caused by errors in manufacturing, fabrica-
tion tolerances, assembly and installation can lead to modes
becoming frequency degenerate. This gives rise to mode
mixing, whereby the component modes combine to form ad-
ditive and subtractive field distributions. Here we look at the
mixing of transverse magnetic (TM) modes and locate prob-
lematic combinations where field strength enhancements
can lead to increased on-axis loss factors and dipole kick
factors, both of which can have adverse effects on the beam
emittance and energy.

Speaker: Anthony Gilfellon (Cockcroft Institute)

WEP5088_edited_version.pdf

16:00 Improved resistive wall effective radius taking into account Yokoya factors

When computing the resistive wall impedance, one must account for variations in beam pipe aperture, conductivity, and beta function. This can be done by either summing individual contributions or using an "effective radius" in an analytic formula. However, the standard "effective radius" formula has limitations: it ignores cross-plane influences and lacks formulas for quadrupolar or monopolar wakes.
This paper introduces an improved "effective radius" definition using Yokoya factors, addressing these limitations. This updated formula was used to develop SOLEIL’s new impedance model, significantly improving the agreement between simulated and measured instability thresholds.

Speaker: Alexis Gamelin (Synchrotron soleil)

16:00 Improved Space-Charge Simulation Studies for the Muon Collider Proton Compressor

In the current design of the International Muon Collider Collaboration proton complex, a compressor ring rotates the proton beam in longitudinal phase space to produce the short pulses required for muon production. Previous simulation studies of this compressor have relied on 2.5D Particle-in-Cell (PIC) space charge in Xsuite, which employs a static mesh (i.e., it does not adapt to an evolving beam size). To validate these results, an adaptive mesh has been implemented and 3D space charge has been tested, followed by a convergence study and a tune sweep. A resonance phenomenon originally believed to be space-charge driven has been investigated, and the selection of an optimal working point has been further explored. The results show that both the adaptive mesh and 3D space charge introduce significant differences relative to the previous configuration, although compression to 2 ns should still be feasible provided the severity of micro-bunching is not significant. This work presents an overview of these studies and discusses their implications for optimization of the compressor.

Speaker: Natalia Milas (European Spallation Source)

16:00 Improving Energy Spread of MESA Beam in ERL Operation

MESA, the Mainz Energy-Recovery Superconducting Accelerator, currently under commissioning at Johannes Gutenberg University Mainz, is designed to operate in two modes: external beam (EB) mode, with 150 μA polarized electrons at 155 MeV serving the P2 experiment, and energy-recovery linac (ERL) mode, with an unpolarized beam of 1–10 mA at up to 105 MeV for the MAGIX experiment. The latter requires precise control of the energy spread and the bunch length across various beam energies of 30, 55, 80, and 105 MeV. Comprehensive simulations were conducted using the tracking code ELEGANT; starting with a 4-ps bunch length, the full acceleration and deceleration process in ERL mode was modeled by optimizing the RF phase and the accelerating gradient field in off-crest operation, which results in the desired energy gain in each linac section. To reach the lowest energy spread, an appropriately selected longitudinal dispersion in the recirculation arcs is required. Since the beam is more sensitive to RF curvature and space-charge effects at low energies, reducing the bunch length by 50 % results in a small energy spread. Consequently, the injection arc lattice is optimized by adjusting the arc momentum compaction R56 as the primary tuning parameter. The integration of a chirp and R56 tuning enables efficient, controlled bunch compression and thereby enhances the overall beam quality.

Speaker: Mrs Esraa Khidr (Johannes Gutenberg University Mainz)

WEP5023_edited_version.pdf

16:00 Improving Injection at Diamond using Dimensionality Reduction Techniques and Bayesian Optimisation

Injection efficiency into the Diamond Light Source Storage Ring (SR) is currently optimised by operators performing a grid scan over the final pair of corrector magnets inside the Booster-to-Storage Ring (BTS) transfer line. The phase advance between the pair is sufficient to provide good control over the position and angle of the beam as it enters the SR. However, the method is slow and the strengths of the corrector pair can approach power supply limits over time as machine conditions drift. We propose a Bayesian optimisation algorithm to optimise leading right-singular vector coefficients obtained from a Singular Value Decomposition (SVD) of the BTS response matrix over all corrector magnets, improving sample efficiency. We further transform the proposed coefficients through a non-linear map to restrict the set of solutions to a desirable range as determined by the user. We compare our results to the grid scan technique and suggest further refinements to the algorithm.

Speaker: Shaun Preston (University of Oxford, John Adams Institute for Accelerator Science, Diamond Light Source)

WEP5057_edited_version.pdf

16:00 Improving Peak Prediction in MEBT Surrogate Models Using Fourier Feature Mapping

Accurate prediction of localised beam features such as peak loss and rapid envelope oscillations is essential for reliable operation of the Medium Energy Beam Transport (MEBT) at ISIS. Standard neural network surrogate models often struggle to capture these effects due to spectral bias, favouring smooth variations over sharp changes. In this work, we investigate the use of Fourier feature mapping to improve surrogate model performance on high-frequency beam behaviour. The method projects spatial inputs into a sinusoidal basis, enabling the network to represent high-frequency variations more effectively. We train two surrogate models on MEBT simulation data, one using Fourier feature mapping and the other without, and compare their performance in capturing peak regions. Results show that Fourier feature mapping significantly improves peak prediction accuracy while maintaining comparable performance on global beam trends. This demonstrates a straightforward and computationally efficient approach for enhancing surrogate modelling of beam dynamics in low-energy transport systems.

Speaker: jaehoon cha (Science and Technology Facilities Council)

WEP6027_edited_version.pdf

16:00 In Trap Polarisation of Radioactive Ion Beams with the MORA Experiment

The MORA experiment is looking for a signature of CP violation in the nuclear beta decay of trapped and laser polarised ions [1]. The polarisation technique is more efficient than traditional atom trapping techniques by several orders of magnitude, as recently demonstrated on line at IGISOL, in the university of Jyväskylä, Finland [2, 3]. This technique could ultimately enable the delivery of polarised radioactive ion beams to the DESIR hall once MORA returns to GANIL.

This contribution will describe the latest results with the MORA experiment for the polarisation of 23Mg+ beams, and will explore future opportunities for deploying this technique in polarised radioactive ion-beam experiments beyond MORA.

The MORA project is coordinated by GANIL and brings together a consortium including GANIL, LPC Caen, the University of Jyväskylä, and KU Leuven.
It is supported by ANR under contract ANR-25-CE31-4222.

References:
[1]: P. Delahaye et al., «The MORA project,» Hyp. Int., vol. 240, p. 63, 2019.
[2]: N. Goyal et al., «Performances of the MORA Apparatus to test Time Reversal Invariance in Nuclear Beta decay», Eur. Phys. J. A 61, 221 (2025).
[3]: IN2P3 news, 29th of October 2025, https://www.in2p3.cnrs.fr/fr/cnrsinfo/premiere-mesure-du-degre-de-polarisation-dions-radioactifs-avec-lexperience-mora

Speaker: Pierre Delahaye (Grand Accélérateur National d'Ions Lourds)

16:00 Injecting and Ramping Trapped Beam in Hadron Accelerator

In developing an alternative method of jumping transition in the Electron Ion Collider Hadron Storage Ring, simulations have been performed to show feasibility. Many challenges occur while ramping trapped beam. The effect of snapback on the superconducting magnets, longitudinal oscillations, and evolution of the island tune will be presented.

Speaker: Stephen Brooks (Brookhaven National Laboratory)

WEP1304_edited_version.pdf

16:00 Injection losses in the SOLEIL II storage ring: sensitivity to booster and transfer line errors

Injection losses are a key challenge for SOLEIL II commis-
sioning because the reduced storage-ring acceptance makes
off-axis injection highly sensitive to transport and optics
errors. We use multiparticle tracking with a corrected lat-
tice model including realistic static and jitter errors in the
booster and Transfer Line 2 (TL2). The results show that
losses are primarily governed by the injected phase-space
distribution at the MIK. Most particles are intercepted at the
septum and at Straight Section 7 (SDM07), while the injec-
tion acceptance window sets the efficiency for all studied
error scenarios. Emittance exchange improves the horizon-
tal footprint only if the final TL2 focusing errors remain at
the percent level; otherwise, the enlarged vertical beam size
samples the non-linear MIK field and generates large hori-
zontal over-kicks. These results provide practical tolerances
and tuning priorities for top-up commissioning.

Speaker: Laurent Nadolski (Synchrotron soleil)

WEP5008_edited_version.pdf

16:00 Injection Requirements for Electron Swap-Out in the EIC-ESR

The Electron–Ion Collider (EIC) will be the first collider to use electron swap-out injection to maintain high bunch polarization during operation. Meeting the EIC performance goals places stringent requirements on the Electron Storage Ring (ESR) injection process: the injected bunch must be introduced with minimal disturbance to the hadron beam, and electron losses must remain negligible to avoid detector background. This work summarizes the key ESR injection requirements, including orbit accuracy, injected emittance, and fast kicker requirements needed to meet the overall EIC performance requirements.

Speaker: Yue Hao (Facility for Rare Isotope Beams)

WEP1357_edited_version.pdf

16:00 Inovesalib: A Modular Vlasov-Fokker-Planck Solver Framework

The numerical solution of the Vlasov–Fokker–Planck (VFP) equation is a well-established method to simulate the dynamics of electron bunches in storage rings, including their self-interaction through wake fields. Inovesa is an efficient VFP solver architecture that enables accurate simulations of phase space evolution, capturing phenomena such as coherent synchrotron radiation (CSR) and the micro-bunching instability on standard desktop hardware.

Building on this foundation, we introduce Inovesalib, a redesigned and extensible library version of Inovesa that exposes the core VFP solver as a modular C++ API and provides a Python wrapper for seamless integration into user workflows. Inovesalib decouples the solver core from application logic and offers a plugin architecture that allows users to implement custom algorithms without modifying the underlying solver. The redesigned structure turns Inovesa from a standalone application into a flexible simulation framework, suitable for integration into optimization pipelines, machine-learning workflows, and custom tools. We present the library architecture and demonstrate its use in both C++ and Python.

Speaker: Felipe Donoso (Karlsruhe Institute of Technology)

WEP6163_edited_version.pdf

16:00 Integrating Fast Beam Interlocks into an Event-Based Timing System

Accelerators often use separate infrastructures for precise timing and machine protection, which increases cabling, integration complexity and operational overhead. We describe an approach that enhances a standard event-based timing system to provide fast beam interlock functionality on the same platform. Protection logic, flag distribution and rapid reaction paths are implemented directly in the timing firmware, allowing the existing hardware and fibre network used for device triggering to also transport low-latency interlock information. With timing and protection combined, interlock conditions can act immediately on timing outputs while established capabilities such as sequences, delay compensation and timestamping remain fully supported. The system offers flexible configuration of inputs, flags and outputs, and a single operator interface for both timing and protection workflows. Developed in collaboration with Nusano, this solution demonstrates a practical architecture for environments where precise timing and fast protection must operate tightly coupled.

Speaker: Tilen Zagar (Cosylab)

WEP6140_edited_version.pdf

16:00 Integration of Retrieval-Augmented Generation for Knowledge Access in the ELBE Accelerator Control System

The efficient operation of accelerator facilities increasingly relies on rapid access to heterogeneous operational knowledge, including logbooks, interlock reports, machine parameters, and historical archive data. At ELBE (Electron Linac for beams with high Brilliance and low Emittance) we are developing a Retrieval-Augmented Generation (RAG) framework that integrates facility documentation and operational records into a unified AI-assisted support tool for operators. The system indexes the electronic logbook, machine archive data, and subsystem manuals using domain-specific embeddings and a vector database. User queries are processed through a large language model that retrieves the most relevant operational context and produces structured, operator-oriented responses. Early tests show that the RAG system can identify relevant past machine states, extract temporal correlations from archive data, and summarize fault patterns that are typically time-consuming for operators to investigate manually. This contribution presents the system architecture, and data integration challenges toward real-time assistance for accelerator operation.

Speaker: Najmeh Mirian (Helmholtz-Zentrum Dresden-Rossendorf)

16:00 Interlocking of Lattice Skew Quadrupole Circuits in the LHC

The Large Hadron Collider operates with 24 power converter circuits supplying the lattice skew quadrupole magnets for coupling correction. These circuits are currently not interlocked via the Powering Interlock Controller. Recent operational experience shows that a trip of one of these circuits can cause beam losses that can lead to beam dumps via beam loss monitors.
This study employs Xsuite beam tracking simulations to assess the impact of individual skew quadrupole circuit failures on beam losses under realistic LHC Run 3 operating conditions. The simulations identify the circuits that were subsequently connected to the beam interlocking system during the 2025 Year-End Technical Stop.

Speaker: Jan Uythoven (European Organization for Nuclear Research)

WEP1009_edited_version.pdf

16:00 Investigations of betatron coupling and horizontal partial snake resonances at low energies in the AGS

Compensation of depolarizing partial snake resonances using betatron coupling has been demonstrated at the Brookhaven AGS. At the nominal acceleration rate, the depolarization of the proton beam from any one of the 82 resonances is too small to optimize the compensation each individual resonance empirically. The compensation therefore requires accurate modeling of the accelerator lattice and accounting of both known sources of such resonance (the helical dipole and applied skew quadrupole fields) and unknown sources (e.g. sextupole feed-down effects). At low energies in the AGS these efforts are complicated by the large optical effects of the helical dipoles and the near-integer vertical tune requires to avoid strong vertical spin resonances. Individual resonances can be investigated by crossing the resonance more slowly, in this case at fixed energies with a slow tune ramp. We report here on progress in both the modeling and experimental investigations into these depolarizing mechanisms.

Speaker: Vincent Schoefer (Brookhaven National Laboratory)

WEP4334_edited_version.pdf

16:00 Investigations of Non-Linear Optics Control Knobs for the FCC-ee

The non-linear effects that arise from misalignment and field errors have been shown to degrade both the dynamic aperture (DA) and (MA) in simulation of the Future Circular Collider electron-positron machine (FCC-ee). This study focuses on using multipoles, such as octupoles, to control the amplitude detuning and higher-order chromaticity as well as investigation of dedicated non-linear correctors to control affected resonance driving terms (RDTs). These non-linear parameters are often coupled and the relative strength with which lattice elements act on each non-linearity depends on the local optical parameters. Studies were performed on the placement and strength of non-linear lattice elements to develop orthogonal correction knobs and first attempts at higher-order corrections to recover the reduced DA and MA are explored.

Speaker: Patrick Hunchak (University of Saskatchewan)

WEP1311_edited_version.pdf

16:00 Ion transport optimisation at the Low Energy Branch

In every accelerator beamline, the goal is to achieve the highest possible desired beam throughput.

When the beamline consists of only a few ion optical elements, beam transport optimization is achieved by adjusting a few knobs, by an experienced operator.

At the Jožef Stefan Institute, we are currently developing the Low Energy Branch (LEB) *, designed for high-precision ion implantation. The branch operates in a versatile regime of beams spanning the entire periodic table at various ion energies. This versatility makes beam transport optimization challenging, even for experienced operators, despite the limited number of ion optical elements: Einzel lenses, an electrostatic beam bender, x-y steerers, a Wien filter, and a 90-degree dipole magnet.

In this proceeding, we present the cost functions for optimizing ion transport through the LEB and describe how we determine the optimal settings for the LEB's optical elements.

The optical elements are modeled using first-order transfer matrix formalism, with the figure of merit for beam optimality measured by Faraday cups and Allison emittance scanner. The beam element parameters are controlled via the EPICS control system*.

Speaker: Ziga Brencic (Jožef Stefan Institute, University of Ljubljana)

WEP5128_edited_version.pdf

16:00 Ion Trapping Studies and Mitigation Strategies for the EIC ERL-Based Strong Hadron Cooler

An Energy Recovery Linac based strong hadron cooler was previously considered for the Electron-Ion Collider. The required electron beam parameters for variable-energy strong hadron cooling place significant constraints on ion trapping and collective effects. This paper presents initial studies of these constraints through a combination of analytical modelling and numerical simulations of ion production, trapping behaviour, and mitigation strategies. A multi-bunch tracking framework based on ELEGANT with the ionEffects module is used to simulate machine operation over millisecond time scales, corresponding to more than 3 × 10^5 electron bunches. The simulations include modelling of ionisation processes together with transverse electron–ion dynamics, allowing the evolution and accumulation of ions to be investigated. Analytical expressions based on Gaussian beam distributions are used to estimate ion trapping conditions and benchmark the simulation results. A bi-periodic bunch spacing scheme is also investigated as a possible mitigation method by detuning the ion oscillation frequency. These studies provide an initial assessment of ion trapping in the strong hadron cooler and demonstrate possible approaches for reducing beam–ion effects.

Speaker: Rancheng Bi (Lancaster University, Cockcroft Institute)

WEP5144_edited_version.pdf

16:00 Koopman-Stabilised World Models for Offline Reinforcement Learning in Accelerator Control

Particle accelerators generate vast amounts of historical data from logs, yet learning-based control often still relies on risky online optimisation. To better utilise this data and avoid online exploration, we present an offline reinforcement learning (RL) workflow. First, we use XSuite to generate high-fidelity trajectories for steering tasks across representative scenarios, including optics variations, alignment errors and jitter, yielding a synthetic dataset of expert and non-expert behaviour. Second, we learn an uncertainty-aware, Koopman-stabilised world model from this data, in which nonlinear beam dynamics are lifted into a latent space with approximately linear, spectrally constrained evolution and a regularised residual term. This structure provides numerically stable long-horizon rollouts and estimates of epistemic uncertainty in latent space.

The resulting surrogate environment enables model-based offline RL, where policies are optimised entirely on pre-generated data while epistemic uncertainty is used to detect distribution shift and enforce soft safety constraints. We benchmark these offline RL policies against a PPO agent trained directly in simulation. Results show that policies trained purely offline on the Koopman world model can match online PPO performance without requiring any interaction with the real machine. This demonstrates a safe, reproducible pathway for turning historical accelerator data into effective learning-based control policies.

Speaker: Simon Hirlaender (University of Salzburg)

16:00 LANSCE 2026 Operations Status and an Upcoming Modernization Project

The Los Alamos Neutron Science Center (LANSCE) User Facility has just celebrated over 53 years of beam operations. LANSCE is a kilometer-long H+/H- linear accelerator serving five active and unique user facilities. In 2024, due to several issues, including spare klystron inventory being at a critically low level, operations were limited to a low energy. In 2025, resuming full-energy operations proved to be more challenging than originally anticipated after a significant portion of our equipment had been off for over a year. We are moving forward with a three-pronged approach to address our klystron inventory issues. To address a subset of obsolescence and reliability issues, the LANSCE Accelerator Modernization Project (LAMP) is underway and received US Department of Energy CD-0 (Mission Need) approval on November 25, 2024. The project is developing processes for risk reduction, including making use of a unique facility at LANSCE which includes a beam line tunnel for accelerator development. This area will be used to stage a major portion of the LAMP Upgrade prior to installation. We will discuss the status of LANSCE operations, LAMP, short-term and long-term paths forward.

Speaker: Mark Gulley (Los Alamos National Laboratory)

16:00 LAT: a 9-MeV prototype “front-end” for the LANSCE Accelerator Modernization Project

The LANSCE Accelerator Modernization Project (LAMP) is designing a modernized front-end, up to 100-MeV, for the LANSCE accelerator. The LAMP front-end will replace the two Cockcroft-Waltons with a single Radiofrequency Quadrupole and replace the Drift Tube Linac (DTL) with a modernized version. As part of the Technical Readiness Evaluation there are Critical Technical Elements (CTEs) that need to be addressed for the project to achieve Critical Decision 3. To address these CTEs and as risk mitigation for an accelerator that is in current operation, we plan to assemble LAMP from ion sources through the first DTL Tank, approximately 9-MeV, in an adjacent facility. This paper discusses the current status and future work of this plan: LAT.

Speaker: Remington Thornton (Los Alamos National Laboratory)

WEP4318_edited_version.pdf

16:00 Linear and Nonlinear Effects of Fringe Fields on the Single-Particle Dynamics in the Helium Light Ion Compact Synchrotron

HeLICS (Helium Light-Ion Compact Synchrotron) is a proposed cancer treatment facility developed within the Next Ion Medical Machine Study (NIMMS) at CERN, designed both for clinical treatment with protons and research with helium ions. Consisting of a triangular lattice with six 60 degree combined-function magnets with 30 degree edge angles, this machine challenges the current treatment of fringe fields in beam dynamics simulations. At present, accurate maps for the fringe fields of curved combined-function magnets with edge angles are not available in the literature. This work investigates the linear and non-linear effects of these fringe fields through the framework of resonance driving terms, providing an alternative approach to quantify their influence on single-particle dynamics.

Speaker: Silke Van der Schueren (European Organization for Nuclear Research)

16:00 LLRF Prototype Design for the 1.3 GHz Cryomodule of the Shenzhen Superconducting Soft X-ray FEL

This paper presents the design and preliminary test results of a Low-Level Radio Frequency (LLRF) prototype system developed for the 1.3 GHz standard cryomodule of the Shenzhen Superconducting Soft X-ray Free Electron Laser (S3FEL). The system is implemented within an MTCA.4 platform, integrating eight RF controller boards for superconducting cavity field acquisition and microwave excitation control to stabilize the RF field and ensure steady electron beam acceleration, alongside two tuner controller boards for driving four coupler motors, four cavity tuner motors, and eight piezoelectric actuators (PZTs). A high-speed peer-to-peer (P2P) backplane bus enables real-time communication between RF and tuner control boards. The report outlines the hardware architecture of this modular LLRF system and discusses initial functional and performance tests, demonstrating its suitability for meeting the precise stability requirements of the S3FEL project.

Speaker: Zhiyuan Zhang (Institute of Advanced Light Source Facilities, Shenzhen)

WEP6603_edited_version.pdf

16:00 Localized Response Basis for Data-Efficient Transverse Beam Distribution Reconstruction Using a Multimode Fiber Relay

Transverse beam imaging in radiation areas can be supported by relaying scintillation light through a multimode fiber (MMF) to a camera placed in a shielded area. However, the MMF scrambles the input, so a trained model is required to recover the beam distribution. This work studies a data efficient calibration method in which measured input and MMF output basis pairs are used as building blocks to synthesize training data for the reconstruction model. After an initial digital micromirror device based validation, the method was assessed using real beam data from CERN CLEAR, where data synthesized from a raster scan basis were used to train a convolutional autoencoder. The best model using this strategy achieved 7.37% mean normalized root mean square error (RMSE) across four transverse beam parameters, compared with 6.02% for a random scan reference model using roughly twice as many fully paired random scan samples. These results suggest that basis-based synthesis training, when combined with suitable beam image priors, can reduce reliance on large random scan MMF calibration datasets by replacing part of the calibration with a controlled scan of fixed size.

Speaker: Mr Qiyuan Xu (Cockcroft Institute)

WEP6024_edited_version.pdf

16:00 Long term tracking of high intensity bunched beams with collisionality

Modeling of the beam dynamics of high intensity bunched beams including
the effect of Coulomb collision is challanging. This is because the
proper modeling of the collisionality must be consistent with the
computation of the mean field. To model this process a Monte-Carlo-
based PIC framework has been developed and implemented in the MICROMAP
library in order to compute collisionality and space-charge mean fields
with a fully 3D spectral Poisson solver. The aim of this development is
to achieve reliable predictions of IBS-driven emittance growth and beam
lifetime. In this proceeding we compare and discuss the results from
the long-term beam tracking simulations using this modeling with the
prediction of the analytical IBS predictions to assess the consistency
and accuracy.

Speaker: Giuliano Franchetti (GSI Helmholtz Centre for Heavy Ion Research)

WEP5078_edited_version.pdf

16:00 Longitudinal Beam Diagnostics with a Streak Camera at Taiwan Photon Source

The Taiwan Photon Source (TPS) streak camera system has been used for longitudinal beam studies since the early commissioning stage. This paper first presents a representative high-current instability observation associated with the CU15 insertion device taper and then recent measurements of bunch length and synchronous phase under operation with the superconducting RF (SRF) + passive 3rd harmonic cavity (HC), here abbreviated as SRF HC. The CU15 case shows different instability behaviors along the fill pattern in streak images. The SRF HC measurements provide bunch-by-bunch information under different fill patterns and SRF HC settings for comparison of bunch lengthening and phase shift. Under operation with the passive SRF HC, a phase drift of about 35 ps is observed along the bunch train, consistent with transient beam loading under quasi-uniform filling. These measurements show that the streak camera is useful for longitudinal diagnostics and machine studies at TPS.

Speaker: Chunyi Wu (National Synchrotron Radiation Research Center)

16:00 Longitudinal Beam Dynamics Investigations at the GSI UNILAC for non-relativistic ion beams

At the heavy-ion accelerator UNIversal Linear ACcelerator (UNILAC) at GSI Helmholtz Center for Heavy Ion Research (GSI) in Darmstadt, measurements of the longitudinal emittance were performed using a Fast Faraday Cup (FFC) installed in a dispersive section. The FFC provides high-resolution, time-resolved measurements of the charge distribution along the longitudinal beam profile. Different buncher settings were applied to study the longitudinal beam dynamics and identify the phase and energy foci at the FFC location. Based on these measurements, beam dynamics calculations were carried out to determine the longitudinal emittance at the exit of the Alvarez section. Measurement and calculation results will be presented.

Speaker: Nimue Schmidt (GSI Helmholtz Centre for Heavy Ion Research, Technical University of Darmstadt, Helmholtz Institute Mainz)

WEP6045_edited_version.pdf

16:00 Longitudinal beam dynamics simulation for gold ion acceleration in the J-PARC MR

The J-PARC Main Ring (MR) is a high-intensity proton synchrotron, which accelerates protons from 3 GeV to 30 GeV.
In addition to protons, we are considering accelerating heavy ions to GeV/u energies in the MR as part of the J-PARC heavy-ion program (J-PARC HI).
The heavy ions will be injected from the new heavy-ion injector into the J-PARC Rapid Cycling Synchrotron (RCS) and delivered to the MR.
As the first stage of the program, Au ions are considered the ion species to accelerate.
A full stripping beam of Au ions ($^{197}$Au$^{79}$ ) with an energy of 500 MeV/u is injected from the RCS to the MR. Au ions are accelerated up to 11.5 GeV/u and delivered to the hadron experimental facility.
Since the change in revolution frequency during acceleration of Au ions is larger than that for protons, additional cavities dedicated to ion acceleration or modifications to the existing RF cavity will be needed to cover a wider frequency range.
To estimate the RF system requirements for accelerating Au ions in the MR, we conducted a longitudinal beam dynamics simulation.
In this presentation, we present the simulation results with various harmonic numbers and acceleration times.

Speaker: Yasuyuki Sugiyama (High Energy Accelerator Research Organization)

WEP4644_edited_version.pdf

16:00 Longitudinal beam stability in HL-LHC

Recent studies showed that the broadband impedance in synchrotrons can significantly alter the longitudinal multi-bunch instability threshold. The results of the beam-based impedance measurement campaign in the Large Hadron Collider (LHC) reveal a discrepancy with predictions based on the present impedance model. A larger imaginary impedance with a lower roll-off frequency would reproduce the observations. Since the impedance will be impacted by the High-Luminosity (HL) LHC upgrades, longitudinal beam stability needs to be carefully re-evaluated. This contribution discusses the outcome of the semi-analytical analysis for the HL-LHC parameters together with the updated broadband impedance model. Future benchmark measurements are proposed to probe the multi-bunch instability threshold driven by the partially compensated main RF cavity impedance. Finally, possible mitigation measures to increase the instability threshold are discussed.

Speaker: Ivan Karpov (European Organization for Nuclear Research)

WEP5109_edited_version.pdf

16:00 Longitudinal Matching and Timing Control Studies for the PERLE Energy Recovery Linac

In an Energy Recovery Linac (ERL), precise longitudinal dynamics control is essential for both delivering the required bunch parameters at the interaction points and for enabling energy recovery. This paper will specifically talk about these studies for the PERLE accelerator. PERLE (Powerful Energy Recovery Linac for Experiments) is a proposed high-power ERL delivering a 250 MeV, 20 mA beam (5 MW). Its multi-pass lattice combines the energy of circular machines with the beam quality of a linac, but also inherits their main limitations. In particular, this paper will present studies done of longitudinal matching, this means setting the right correlation between the particle’s longitudinal position and its energy, as well as developing a chicane for timing control.

Speaker: Janine Issa (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

16:00 Longitudinal microwave instability study at transition crossing in the CERN PS

The beam quality of high-intensity proton and ion bunches in the CERN Proton Synchrotron (PS) is limited by a longitudinal microwave instability at transition crossing. This single-bunch instability manifests itself as a rapid longitudinal emittance blow-up and impacts, for instance, the intensity and bunch length to the AWAKE experiment. In this contribution, results of complete parameter scans are presented to experimentally establish the beam stability limits. These are compared to detailed tracking simulations with the BLonD code, including collective effects with the longitudinal impedance model, beam feedback loops, and the gamma transition jump. Remarkable agreement with measurements is obtained for the instability thresholds and micro-bunch structures. Nonetheless, the characteristics of the simulated instability strongly depend on the modelling of longitudinal space charge, which focuses the micro-bunches but also introduces significant numerical noise. The results improve the understanding of performance limitations due to transition crossing and guide future mitigation strategies.

Speaker: Alexandre Lasheen (European Organization for Nuclear Research)

WEP5111_edited_version.pdf

16:00 Longitudinal momentum halos – Risk of the fractional velocity particles in high-current hadron linacs

Recent hadron linacs, such as the IFMIF accelerator [1], aim to achieve an average beam current beyond 100 mA. In addition, a single-cell cavity linac for nuclear waste transmutation [2], which just started its development, is expected to deliver continuously a D+ beam of 1 A. In such high-intensity beam linacs, even sub-percent levels of beam losses can lead to significant activation. Therefore, highly accurate studies of beam halo dynamics are necessary to evaluate the losses with accuracy two orders of magnitude greater than existing evaluations. For this purpose, the methodology and simulation framework should be reconsidered to ensure required accuracy of the particle tracking. In this study, we focus on longitudinal momentum halos formed as fractional velocity particles. The discrete dynamical model of a simplified drift tube linac has demonstrated stable capture of these particles by fractional velocity radio-frequency buckets and their continuous acceleration. Furthermore, analysis of the stability conditions of periodic focusing channels has suggested that these halos can survive even in the downstream region. Eventually, we provide a fundamental discussion [3] on acceleration and transport of halo particles that naturally arise in high intensity linacs.

[1] I. Podadera et al., Nucl. Fusion 65 122011 (2025).
[2] H. Okuno, et. al., Proc. Jpn. Acad. Ser B 95, 430 (2019).
[3] submitted to Phys, Rev. A&B (2025).

Speaker: Kouki Hirosawa (National Institutes for Quantum Science and Technology)

16:00 Low emittance beam transport system of the position damping ring for the Super Tau Charm Facility

The Super Tau-Charm Facility is a high-luminosity electron–positron collider operating at a center-of-mass energy range of 2–7 GeV. The stringent requirements for beam brightness and stability pose significant challenges to the injector transport system, especially the positron transport lines of the damping ring. Beam transverse emittance is one of the primary parameters, which is influenced by a mass of components in the lattice design. In this study, a newly developed multistage optimization method is employed to optimize multiple sets of quadrupole strengths along the transport line. The optimized results effectively suppress the emittance growth and maintain compliance of other parameters with damping ring requirements. These results provide a practical reference for the optical design of high-brightness transport systems in next-generation electron–positron colliders.

Speaker: Binghao Zhang (University of Science and Technology of China)

WEP1623_edited_version.pdf

16:00 Low-power test of bridge coupler connected to tank in disk-and-washer structure for muon acceleration

A muon linear accelerator is under development at J-PARC for precise measurement of the muon anomalous magnetic moment (g-2) and search for the electric dipole moment (EDM). The disk-and-washer (DAW) structure is employed to accelerate muons from 30% of the speed of light (kinetic energy = 4 MeV) to 70% (40 MeV) at 1296 MHz. The muon DAW consists of tanks accelerating the muons and bridge couplers that couple the tanks and focus the beam using an internal quadrupole doublet. A bridge coupler prototype was fabricated and tested at low power. This Low-power test focused on measuring resonant frequencies, Q-value, and electric field distribution. Furthermore, the bridge coupler prototype was connected to a tank prototype and tested at low power to understand the effects of the connection. This paper summarizes these results and discusses the prospects for actual machine production.

Speaker: Ayaka Kondo (Nagoya University)

WEP4631_edited_version.pdf

16:00 Machine Learning–Driven Optimization of Positive Ion Beams on the LUTEX Irradiation Facility

Lutex is a high-performance irradiation facility providing the world’s largest testing area (400 × 700mm2). It delivers light-ion beams with very high fluxes at 300keV/u (∼5000km/s) for H+ up to 4×109 protons/cm2/s. This enables rapid reproduction of extreme exposure conditions and allows for short time qualification of a material lifetime. For comparison, a typical solar storm reaches only 3keV/u (∼600km/s) and 0.2 protons/cm2/s.
Operating a continuous accelerator such as Lutex requires achieving beam stability conditions on energy and current over a long period of time tailored to experimental needs. The difficulty resides in the change of a large number of input parameters, in their nonlinear interactions and in the variability of irradiation conditions.
Pantechnik is developing a Machine Learning model designed to facilitate beam tuning, to optimize beam quality, and to predict parameters required for production of continuous beam. The model exploits data collected from plasma generation, extraction, transport, separation, and dose measurements to learn the relationship between machine settings and resulting beam performances. After data preprocessing and feature extraction, several approaches, including Bayesian optimization and nonlinear regression methods, will be benchmarked to predict and optimize the beam current as a function of operating parameters.

Speaker: Antoine Breteaux (École Nationale Supérieure d'Ingénieurs de Caen)

WEP6004_edited_version.pdf

16:00 Machine protection considerations for transfer of the high-intensity proton beam to the BDF at CERN

The new beam-dump production target serving for Search for Hidden Particles (SHiP) experiment will be built just upstream of the ECN3 experimental cavern in CERN’s North Area. The future experiment requires an increase in the number of protons delivered to this location to over 4e19 per year. This necessitates upgrades of the primary beam transfer lines and their optics coming from SPS directly to the new Beam Dump Facility (BDF). The modifications aim to minimise beam loss and to avoid significant radioactivation of the equipment. In this work we describe the mitigation of possible failure scenarios related to the design of the beam delivery systems across the North Area, in order to protect the accelerator, its infrastructure, and most notably the BDF target.

Speaker: Aleksandr Gorn (European Organization for Nuclear Research)

16:00 Magnetic field interference and compensation of quadrupole magnets in CSNS RCS

During the beam power upgrade of the Rapid Cycling Synchrotron (RCS) of the China Spallation Neutron Source (CSNS), 16 additional trim quadrupoles were installed for beam optics correction. However, they are relatively close to the nearby main quadrupole magnets, resulting in a strong field interference effect. The interference causes a serious distortion of the lattice parameters and can lead to significant beam loss for high-intensity beams. In this paper, firstly, the three-dimensional electromagnetic field software OPERA is used for simulation, and the magnetic field integral changes are accurately calculated. Then, a systematic analysis was conducted on the effects of integrated magnetic field variations on both the betatron tune and beta function using the accelerator physics calculation software MADX. Additionally, the multi-particle tracking software pyORBIT is utilized to simulate beam loss. The results show that the original lattice parameters are distorted and beam loss is significantly increased by this effect. To obtain accurate magnetic field interference data, indirect measurements were performed employing the orbit response matrix method. Experimental results demonstrate remarkable consistency with numerical simulations. On this basis, beam compensation experiments are carried out and beam loss is successfully reduced.

Speaker: Yuwen An (Institute of High Energy Physics)

WEP4638_edited_version.pdf

16:00 Matching of Crystalline Beams into the BNL Booster

A method has been developed to match large three-dimensional Coulomb crystals into existing accelerators. Simulations show bunch temperatures below 1 Kelvin persisting for thousands of turns in the BNL Booster and for tens of thousands of turns in an idealised ring (both with no cooling). Focussing forces balance space charge to give zero net phase advance and the crystal structure can be preserved for tens of milliseconds. Magnetic focussing confines all three dimensions of the bunch without RF, since the bunch rotation in the ring plane is not at the ring revolution frequency. A zero temperature, uniformly-filled ellipsoid of charge gives a 15-parameter model that can be used for matching and linear stability analysis.

Speaker: Stephen Brooks (Brookhaven National Laboratory)

WEP4324_edited_version.pdf

16:00 Measurement of chromatic resonance driving terms in the LHC

The $3Q_y$ resonance is of particular concern at LHC injection given its potential to degrade the lifetime and the machine dynamic aperture. During measurements of the chromatic linear optics for the 2025 LHC commissioning, a large variation of the $3Q_y$ resonance strength at different momentum deviations $\delta$ was noticed. Further studies have been performed in order to assess the contribution to this variation from higher order multipoles, in particular from octupole and decapole fields. Benchmarking has been performed to the LHC magnetic model pointing to a large discrepancy in the skew-octupole sources present at injection. Methods and results of this analysis are presented in this work.

Speaker: Mattia Stefanelli (European Organization for Nuclear Research, National Institute for Subatomic Physics)

WEP5073_edited_version.pdf

16:00 Measurement of displacement cross section using 440-GeV/c protons at CERN HiRadMat

As a material-damage index due to the radiation, displacement per atom (dpa) is used widely, which is given by the particle fluence and the displacement cross section. The displacement cross section can be obtained by the electrical resistivity change of target materials due to the proton irradiation by the Matthiessen rule. The sample had to be cooled at cryogenic temperature to observe the very small resistivity change and sustain the damage. To obtain the cross section data, J-PARC and JAEA conducted experiments using protons in the kinetic energy range from 100 MeV to 120 GeV. The experimental results were compared with the calculation based on the Norgett-Robinson-Torrens model (NRT-dpa), which is widely utilized to determine the dpa. A recent model based on the athermal recombination corrected model (arc-dpa) showed good agreement with the experiment. It is of interest to compare the experimental cross section with the calculation model at high energy, where relativistic effects increase energy deposition. To obtain the experimental data, an experiment at CERN HiRadMat using 440 GeV protons was conducted. In this session, the preliminary results are cross-validated with Monte-Carlo simulations, using the well benchmarked program PHITS and FLUKA. It was found that PHITS and FLUKA calculations with arc-dpa reproduced the experiment well. On the contrary, the NRT-dpa calculation overestimates the experimental data. Also, future plans will be discussed in the session.

Speaker: Shin-ichiro Meigo (Japan Atomic Energy Agency, Japan Proton Accelerator Research Complex)

WEP4651_edited_version.pdf

16:00 Measurement of local chromaticity in the LHC

Local chromaticity can be defined as the local variation of the total betatron phase advance with momentum deviation $\delta$, and it can be interpreted as a measurement of the chromaticity generated over a limited segment of the lattice, rather than for the entire ring. It can be a useful tool to understand various insights of the beam operation, in particular how the phase is locally modulated by $\delta$ and how the overall chromaticity builds up along the lattice. The local chromaticity was first evaluated in the Large Hadron Collider (LHC) during the Run 3 commissioning in 2025, when a large RF frequency scan was performed up to $\pm \, $350 Hz, revealing a very large discrepancy with respect to the LHC optics model. This paper presents the methods and the results of the analysis.

Speaker: Mattia Stefanelli (European Organization for Nuclear Research, National Institute for Subatomic Physics)

WEP5071_edited_version.pdf

16:00 Measurements of CSR radiation at KARA using novel thin-film lithium niobate electro-optical sensors

Electro-optical detection provides a powerful method for characterizing the electric fields of relativistic electron beams and their emitted radiation. We report on the use of novel thin-film lithium niobate electro-optical sensors for the detection of freely propagating terahertz (THz) pulses and, for the first time, measurements of coherent synchrotron radiation (CSR) at the Karlsruhe Research Accelerator (KARA). The thin-film lithium niobate sensors, implemented as integrated Mach–Zehnder interferometers, combine a strong electro-optical response with engineered velocity matching and a compact device geometry, enabling sensitive detection of transient THz fields. Using these Mach–Zehnder interferometer waveguide structures, we demonstrate efficient coupling of CSR to the sensors and present first measurement results.

Speaker: Stefan Funkner (Karlsruhe Institute of Technology)

16:00 Microwave Instability Modelling for SOLEIL II

There are two main sources of high-frequency longitudinal impedance: coherent synchrotron radiation (CSR) and high-frequency NEG-coated resistive wall impedance. They can drive microbunching instability, which is a potential risk to maintaining stable and low energy spread beam. To address this, these effects are now integrated into the particle tracking code \texttt{mbtrack2}. This paper examines their impact on beam stability in the SOLEIL~II storage ring, considering the combined influence of intrabeam scattering, low-frequency longitudinal impedance, and a harmonic cavity.

Speaker: Vadim Gubaidulin (Synchrotron soleil)

WEP5105_edited_version.pdf

16:00 Mitigating the periodic resonance crossing in high-intensity bunches by multi-RF

The periodic resonance crossing induced by space charge in bunched beams has been studied
in many aspects. The criticality of the phenomenon appears in regimes of storage for hundreds
of synchrotron oscillations, by inducing a slow diffusion, which is very difficult to contain.
The pseudo-stochasticity of the dynamics of the periodic crossing makes the phenomenon
very difficult to frame in a theory, and full simulations are necessary to predict
emittance growth or beam loss.

A possible mitigation of this effect can be reached via resonance compensation, a process that might
be very long and that requires very detailed studies of the actual machine properties. Other approaches
are also pursued with space-charge compensation or a special magnet design.

We propose here a first investigation based on a different approach: by using a proper combination
of RF harmonics, we shape the longitudinal bunch profile so as to make the periodic crossing less
effective. The concept is explored in the CERN PS Booster in a dedicated experimental setup:
the first experimental findings are very promising and encourage this to be a new line of
investigation.

Speaker: Giuliano Franchetti (GSI Helmholtz Centre for Heavy Ion Research)

WEP5079_edited_version.pdf

16:00 Mn-Doped 0.6BiFeO₃–0.4BaTiO₃ Ferroelectric Ceramics and PLD Thin Films for Fast-Tuning RF Components in Particle Accelerators

Efficient electron beam acceleration requires precise synchronization between beam dynamics and RF phase–amplitude modulation, which demands fast and reliable tuning systems. Conventional ferrite or mechanical regulators are limited by slow response times, prompting interest in ferroelectric materials for high-power RF phase shifters and tuners. In this work, self-propagating high-temperature synthesis (SHS) was employed to fabricate Mn-doped 0.6BiFeO₃–0.4BaTiO₃ (BF–BT) ceramics. Optimized milling and sintering conditions yielded dense ceramics with favorable dielectric and magnetic properties. Thin BF–BT films deposited by pulsed laser deposition (PLD) from BF-BT ceramic targets were integrated into bulk acoustic wave solidly mounted resonators (BAW-SMRs). Structural, surface, and electrical characterizations, including XRD, 3D optical profilometry, and dielectric–magnetic measurements, confirmed uniform nanoscale roughness, conformal electrode coverage, and dual tunability under external fields. These results highlight the potential of Mn-doped BF–BT compositions for next-generation fast-switching RF components in particle accelerator technologies.

Speaker: Dr Armen Grigoryan (Center for the Advancement of Natural Discoveries using Light Emission)

16:00 Model Predictive Control and ML for Control and Estimation: Application to the IPF Beamline at LANSCE

The Isotope Production Facility (IPF) at Los Alamos Neutron Science Center (LANSCE) contains an adjustable collimator, able to handle various aperture sizes. The collimator contains integrated temperature and current measurements provided for each collimator segment, for diagnostic and feedback purposes. To simplify collimation, we plan to replace this collimator system with a 'virtual' collimator, combining beam position monitors (BPM) and other simpler diagnostics with physics based machine learning techniques to automate tuning of the beamline. Details of the algorithms are presented, as well as some preliminary results.

Speaker: Alan Williams (Los Alamos National Laboratory)

16:00 Modeling and Field Analysis of the LEIR Bending Magnets and Optics Integration

This contribution presents the modeling of the dipole magnets of the Low-Energy Ion Ring (LEIR) at CERN. The LEIR dipoles are iron-dominated C-type 90° sector magnets. Each LEIR dipole consists of 6 blocks of 1-meter-long laminated steel yoke with copper coils. The biggest challenges of the design stem from the axial air gaps and the varying angles between the blocks, causing unwanted harmonics in the magnetic field. These harmonics cause mismatches between measured and predicted linear optics parameters in LEIR. Due to the unconventional magnet design, efforts are made to obtain 3D field maps and multipole field components with high accuracy by modelling the magnet precisely in 3D. The study has started with 2D Finite Element Analysis (FEA) in different cross-sections and then continued with the 3D FEA analysis for the examination of the integrated field and the multipole components. The FEA is computed using different programs for comparison and to increase the model accuracy by fine-tuning. Finally, the model results have been compared with the beam-based optics measurements, and the efficiency of the models has been evaluated.

Speaker: Halil Deveci (European Organization for Nuclear Research)

WEP5038_edited_version.pdf

16:00 Modeling and Measurements of the Impact of Dipole Fringe Fields in the Extra Low Energy Antiproton Ring

The ELENA (Extra Low ENergy Antiproton) ring is a compact synchrotron designed to decelerate antiprotons delivered by the Antiproton Decelerator. In ELENA, the beam dynamics is dominated by the dipole edges, making this machine an ideal tool for benchmarking theoretical fringe field models against direct beam measurements. In this paper, we present a comparison of theoretical models and experimental data to characterize the impact of fringe fields and evaluate the accuracy of existing fringe field descriptions.

Speaker: Silke Van der Schueren (European Organization for Nuclear Research)

WEP5085_edited_version.pdf

16:00 Modeling longitudinal beam parameter spreads in the LHC

Roughly 2500 bunches are accelerated to collision energy during physics production in the Large Hadron Collider (LHC). Due to the beam production scheme in the injector chain, a certain spread in bunch length and intensity at injection into the LHC is unavoidable. The variation in these parameters has implications for RF capture, leakage of particles from the buckets at flat-bottom, and therefore the losses at the start of acceleration. Moreover, bunches with particularly high intensity or short length can become unstable. With the doubling of the nominal bunch charge for the High-Luminosity (HL) LHC era, these variations will become increasingly important. Beam tests have been carried out over the past few years in the LHC with beam intensities up to the HL baseline. Based on data from these studies, projections of longitudinal parameter spreads can be made for the HL-LHC era. In this contribution, the parameters of the beams injected into the LHC are examined in detail. The results are combined with semi-analytic models of debunching at flat-bottom to estimate the spreads for HL-LHC scenarios.

Speaker: Rama Calaga (European Organization for Nuclear Research)

WEP1008_edited_version.pdf

16:00 Modeling of Multiturn Injection at SIS-18 for a Train of UNILAC Microbunches

Multiturn Injection is an essential tool for achieving high beam intensities in synchrotrons. At SIS-18, a significant increase in the intensity of the uranium beam is foreseen, by several orders of magnitude up to 1.5x10e15 ions per injection cycle, prior to acceleration and extraction to SIS-100. Under these conditions, any beam losses during injection become critical, both in terms of beam lifetime and the risk of damaging injection system components, in particular the electrostatic septum.
Usually, the optimization of the multiturn injection is carried out by considering only the process of injecting one transverse slice of macroparticles from UNILAC per turn. We present here a three-dimensional modeling of the injection process, which takes into account the longitudinal structure of the injected beam, namely the train of microbunches, and evaluates differences from previous approaches.

Speaker: Annemarie Lauterbach (Goethe University Frankfurt)

WEP5020_edited_version.pdf

16:00 Modeling of Radiation Wakefields using a Scattered Field Formulation

Simulations of particle beam dynamics in electron accelerators need to account for both internal space charge effects and transient electromagnetic waves scattered at chamber walls. Commonly, these effects are treated separately using very different simulation techniques. We have developed a coupling procedure to account for both effects simultaneously by using a scattered field formulation. Here, we combine two field solvers optimized to simulate either the internal beam dynamics assuming free space or the transient electromagnetic wave propagation.

Previously, the coupling procedure was restricted to quasi-static beam behavior, as is sufficient for linear movement and emission from the gun. In this contribution we extend the approach to account for scattered synchrotron radiation wakefields from bent trajectories. We present computational studies of the scattered CSR effect created in bunch compressors, specifically the BC0 of the European XFEL. No restrictions are imposed methodologically on the surrounding geometry or on the flight path of the beam. Hence, our approach is much more general than CSR models used in the past, which assumed for example pre-defined trajectories in between two parallel plates and rigid bunches. At the same time, due to the de-coupled solvers, our method allows to compute particle-particle CSR fields inside the bunch using free-space assumptions, which reduces modeling complexity significantly.

Speaker: Jonas Christ (Technical University of Darmstadt)

WEP5124_edited_version.pdf