IPAC'25 - the 16th International Particle Accelerator Conference

1 Jun 2025, 10:00 → 6 Jun 2025, 13:20 Asia/Taipei

Taipei International Convention Center (TICC)

Ming-Chyuan Lin (National Synchrotron Radiation Research Center), Yoichi Sato (Japan Proton Accelerator Research Complex)

The 16th International Particle Accelerator Conferece at Taipei, Taiwan

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Sunday 1 June

10:00 → 12:00 Student Training

14:00 → 18:00 Student Poster: SUPM

14:00 A compact linear accelerator coaxially integrated with a high-power microwave source

Particle accelerators have long been instrumental in advancing scientific research, medical treatments, and industrial processes. However, traditional radio-frequency accelerators are encumbered by their size, expense, and reliance on external microwave sources.
In this paper, we propose a novel linear accelerator concept that integrates a high-power microwave source directly into the accelerator, which eliminates the need for external microwave drivers, resulting in a more compact, cost-effective, and simplified system.
We designed an X-band backward wave oscillator driven by a hollow continuous electron beam of 50 keV, the high-power microwave generated from which is then input to a centrally positioned X-band standing-wave acceleration structure via a radial coupler. The witness beam, traversing the acceleration structure, can be accelerated from 50 keV to higher than 4 MeV through 10 acceleration cells.
This scheme serves as a fundamental exploration of the possibilities of integrated accelerator designs, paving the way for further innovations in the field of more efficient, scalable and versatile accelerator systems.

Speaker: Zi-Jing Zhang (University of Science and Technology of China)

14:00 Advanced beam tuning and beam measurements techniques in the CLEAR facility

The CLEAR (CERN Linear Electron Accelerator for Research) facility delivers to a wide user community a 200 MeV electron beam with highly flexible parameters.
Running conditions range from single-bunch to multi-bunch operation, with bunch charges from 10 pC to 1 nC, bunch durations from 100 fs to tens of ps, and
includes tunable momentum (30 MeV/c to 220 MeV/c).
Such a variety of beam conditions poses a challenge to the beam instrumentation and to the beam measurements and tuning techniques, even more so given that quite often a rapid switch from one set of conditions to a very different one is required.
In this paper we present several examples of the techniques developed in CLEAR for this purpose and discuss their advantages and limitations.
Examples include emittance measurements and phase space reconstruction procedures by quadrupole scans and beam based alignment methods.

Speaker: Alfred Petersson (European Organization for Nuclear Research)

14:00 Advanced growth and characterization of alkali antimonide photocathodes for bright beam applications

The properties of the photoemitting electron sources are the determining factors contributing to the performance of the most advanced electron accelerator applications such as particle colliders, X-ray free electron lasers, ultra-fast electron diffraction and microscopy experiments. Therefore, low mean transverse energy (MTE), high quantum efficiency (QE) along with long operational lifetime and robustness under high electric fields and laser fluences must be demonstrated by the photocathode for these bright beam applications. Recent investigations have revealed that the epitaxial growth of single-crystal cesium antimonides can be achieved by photocathode growth on lattice-matched substrates. In this paper, the experimental setup for highly promising alkali antimonide photocathode growth by molecular beam epitaxy on lattice-matched substrates and in-situ characterization with reflection high-energy electron diffraction (RHEED) has been presented. To adapt the L-band RF gun of Argonne Cathode Test-stand (ACT) for extensive testing of alkali antimonides in real accelerator conditions, compatible cathode plug design, and smooth transportation process have been developed and described.

Speaker: Tariqul Hasan (Northern Illinois University)

14:00 An optimization of the ILC E-driven positron source with the TPE algorithm

The International Linear Collider (ILC) is a next-generation electron-positron collider based on the superconducting linear accelerator. Many positrons are required for the ILC because beams are not reused in linear colliders. Therefore, the ILC electron-driven (E-driven) positron source system should be designed to optimize efficient positron generation. In this study, we optimize the accelerator parameters including the booster linac RF phase and amplitude, ECS RF phase and amplitude, optics over the system, etc. by the black-box optimizer with TPE algorithm. The results of the optimization are presented.

Speaker: Yodai Sasaki (Hiroshima University)

14:00 Avoiding overcooled ion beams by exciting energy spread through electron cooling

Ion accelerators use electron cooling to improve luminosity and beam lifetime. However, extremely low momentum spread in a cold beam weakens Landau damping, enabling the development of instabilities and potentially decreasing lifetime. To combat this, the NICA Booster electron cooling system allows to generate electron beams with oscillating energy to increase the momentum spread in ion beams. Here we describe the implementation of the energy oscillation technique and provide numerical calculations predicting the achievable momentum spread.

Speaker: Mr Eldar Urazov (Budker Institute of Nuclear Physics)

14:00 Bayesian optimization for generating attosecond X-ray FEL pulses

Ångström and attosecond represent fundamental spatiotemporal scales for studying electron dynamics in various materials. Recently, high-power attosecond hard X-ray pulses have been successfully demonstrated at the European XFEL using the self-chirping operation mode. However, the current process heavily depends on manual tuning by experienced operators, which is time-intensive and less scalable. In this work, we report recent advancements in automating and optimizing the generation of high-power attosecond X-ray pulses using Bayesian optimization techniques. By leveraging machine-learning-based approach, we aim to enhance pulse energy, spectral quality, and operational efficiency, paving the way for more accessible and reproducible attosecond X-ray experiments.

Speaker: Chenzhi Xu (Shanghai Institute of Applied Physics)

14:00 Bayesian Optimization for IP Aberration Correction and Luminosity Tuning in FCC-ee

FCC-ee luminosity optimization relies on measuring realistic signals from Bhabha scattering, beamstrahlung, and radiative Bhabha photons. Initial assessments of beamstrahlung signals examine the change in luminosity, beamstrahlung power and vertex detector hits in response to waist shifts, vertical dispersion and skew coupling at the collision point. These ongoing studies aim to extract IP-aberration-related signals from the energy spectrum, angular distribution, power of beamstrahlung photons, the vertex detector hits and the luminosity. Furthermore, the study integrates all these signals into a machine-learning-based approach for luminosity tuning and optimisation.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

14:00 Beam loading for counter-rotating high-intensity beams in the Muon collider

Muon colliders promise an efficient path to a multi-TeV energy collider facility. In the greenfield study, the final stage of the acceleration chain is planned as a series of four rapid-cycling synchrotrons (RCS). In each RCS, the RF systems are divided into several sections and shared by the two counter-rotating muon bunches. The accelerator requirements are driven by the need to preserve a maximum number of muons by taking advantage of time dilation. Therefore, maintaining a high accelerating voltage throughout the chain is essential, imposing superconducting RF cavities in the GV range. However, the high bunch intensity of up to $2.7\times 10^{12}$ particles per bunch and the 1.3 GHz TESLA cavity’s small aperture will result in induced voltages in the MV range.
In the muon collider, the induced voltage of the counter-rotating beams will additionally impact the cavity voltage.
This contribution presents the cavity voltage modulation and its impact on the beam loss and stability in the strong transient beam loading regime.

Speaker: Mr Leonard Thiele (European Organization for Nuclear Research, University of Rostock)

14:00 Characterisation and mitigation of RF knockout

Beam stacking is a key advantage of Fixed Field alternating gradient Accelerators (FFAs) for high-intensity applications. During stacking, one beam is stored as a coasting beam at the extraction energy while another, incoming beam is accelerated. However, the beam loss mechanism termed RF knockout can occur during stacking and undermine gains in extracted beam current. The accelerating RF program of the incoming beam can cause cumulative displacements in the stored coasting beam and result in significant beam loss. To ensure that beam stacking is a viable technique to extract highest intensities from an FFA, methods to avoid the loss from RF knockout must be established. This study presents results from a series of experiments at the ISIS proton accelerator to characterise and, crucially, to mitigate RF knockout and ensure successful beam stacking with no loss.

Speaker: Carl Jolly (Science and Technology Facilities Council)

14:00 Characterisation of beam dynamics sensitivity to misalignments in the PERLE injector

High current linear accelerators require the precise alignment of accelerating cavities to maintain a high beam quality. The PERLE (Powerful Energy Recovery Linac for Experiments) injector cryomodule is composed of four single-cell cavities, each of which can be independently tuned to allow greater control of the beam at this crucial point. Misalignments can lead to perturbations in the beam trajectory and contribute to an increased emittance and energy spread. Here we present a characterisation of the beam dynamics when various misalignments are applied in the injector. Various misalignments are applied, three in the translation axis (x, y, z), and two rotationally, yaw and pitch (𝚽, 𝚹). A study was conducted to determine the tolerances required misalignments to ensure an acceptable beam quality is maintained at. The results indicate that particular combinations of rotational and translational misalignments are especially detrimental to emittance. These findings provide an important guide for the subsequent design of the booster linac and alignment procedure.

Speaker: Connor Monaghan (University of Liverpool)

14:00 Characterization of the energy spectrum of a 30-MeV cyclotron-based quasi-monoenergetic neutron beam using a time-of-flight spectrometer

We conducted time-of-flight (TOF) measurements to characterize the spectrum of a quasi-monoenergetic neutron beam driven by a 30-MeV proton cyclotron at the National Atomic Research Institute in Taiwan*. Neutrons were produced by irradiating 30-MeV protons onto a 1-mm-thick beryllium target. The developed TOF spectrometer comprised two 2-inch EJ-309 organic scintillators positioned 200 mm from the neutron beam port to detect gamma rays emitted from the target, and a 3-inch EJ-309 scintillator placed at a flight distance of 2940 mm to measure neutrons. As the signals of gamma-ray bursts triggered TOF measurements at an RF frequency of 73.13 MHz, repetitive distributions of coincidence events between gamma-ray and neutron-related signals were observed, resulting in an effective time window of 13.67 ns for measuring neutrons in the energy range of 16.19–30 MeV. The measured neutron spectrum exhibited a peak at 26 MeV, verifying the simulated spectrum obtained from an MCNP Monte Carlo model. Additionally, we developed a fast-timing scintillator module that measured the proton bunch duration as 0.97 ns, enabling accurate estimation of the energy resolution of the neutron spectrum.

Speaker: Tzu-Hsiang Lin (National Tsing Hua University)

14:00 Comparison of Xsuite simulations with measured backgrounds at SuperKEKB

Xsuite is a collection of packages developed to simulate beam dynamics in particle accelerators. It includes Python modules (Xobjects, Xpart, Xtrack, Xcoll, Xfields, Xdeps) that can be seamlessly integrated with one another and with both accelerator-specific and general-purpose Python tools, enabling the study of complex simulation scenarios. The Xcoll module, developed for collimation studies, allows the integration of beam-matter interaction simulations in the tracking through different available scattering models, including those in the BDSIM/Geant4 toolkit. Originally developed for the Future Circular e+e- Collider (FCC-ee) collimation simulation needs, the Xsuite-BDSIM/Geant4 interface is now deployed in full production for FCC-ee collimation studies. A key aspect of such studies relying on complex simulations is their benchmarking against measured data. This paper presents a first comparison of Xsuite collimation simulation results with measured data at the SuperKEKB e+e- collider.

Speaker: Giacomo Broggi (European Organization for Nuclear Research)

14:00 Compensation of an elliptically polarizing undulator in the HLS-II storage ring

The insertion devices (IDs) can severely affect the beam dynamics of a storage ring. Recently, a new elliptically polarizing undulator(EPU) is installed in the Hefei Light Source II (HLS-II) storage ring. The effects of this EPU can be modeled using the kick map method. In this paper, we present the kick map of the EPU with vertical mode and how it affects the beam dynamics. Since the HLS-II storage ring is compact, only four quadrupoles in the same straight section can be used to compensated the ID effect. The compensation result is also reported in this paper.

14:00 Conceptual design of a compact synchrotron for proton-and-helium therapy facilities

In recent years, proton and heavy-ion therapy has become increasingly widespread in clinical applications, and has emerged as one of the important means for cancer treatment. The commonly used particle types for this therapy are protons and carbon ions. However, further research into the biological effect has found that helium ions have both high biological effectiveness and small penumbra characteristics, which enable more precise locate of the tumor while also effectively killing tumor cells. And the highest energy of the helium ions used in therapy is 235MeV/u. Therefore, the equipment size and cost required for helium ions therapy will be significantly less than that for carbon ions therapy. To this end, this paper proposes a design for a helium-ion therapy synchrotron that also possesses the capability for proton therapy. The design employs eight ultra-high field dipole magnets to achieve a compact envelope function. Additionally, the design incorporates both multi-turn painting injection and mismatched injection methods in two directions, significantly minimizing the use of bump magnets. This results in a highly compact accelerator structure.

Speaker: Zihe Gao (Shanghai Institute of Applied Physics)

14:00 Considerations of a round beam operation at PETRA IV

Round beam operation is considered for the planned ultra-low emittance storage ring PETRA IV at DESY, Hamburg. With a natural emittance of 20 pm rad, we evaluate and discuss the advantages and challenges of sharing the emittance between transversal planes. The effect on single and coupled bunch instability thresholds, intra-beam scattering rates and Touschek lifetime of this operation mode are presented.

Speaker: Edgar Cristopher Cortés García (Deutsches Elektronen-Synchrotron DESY)

14:00 Correction of Long-Range Beam-Beam Driven Normal Sextupolar Resonance Driving Terms

Beam-based studies at the LHC injection energy showed that compensation of the strongly driven sextupolar resonance, Qx+2Qy, improved both the dynamic aperture and lifetime of the beam, even when far from the working point and on the far side of the 3Qy resonance. Thus, a reduction of other strong normal sextupolar resonance sources was of interest. In 2024, the first measurements of resonance driving terms with long-range beam-beam (LRBB) interactions were performed. These showed that LRBB was driving the same Qx+2Qy resonance strongly when colliding, in agreement with model predictions. A correction was found for the strongest normal sextupole resonances using the existing sextupole corrector magnets in the LHC, obeying the constraints on the chromatic coupling and the maximum magnet powering. Beam-based tests to validate the response of this correction with non-colliding beams have been performed along with the testing of the LRBB resonance correction during LHC commissioning.

Speaker: Sasha Horney (European Organization for Nuclear Research)

14:00 Design and EM simulations of 750 MHz IH-DTL tank for carbon ion in medical applications

This paper presents the design of 750 MHz IH-DTL (Interdigital H-mode Drift Tube Linac) tank, specifically developed to be part of a carbon ion injector for medical treatment applications. These sections provide a highly efficient solution for ion acceleration in the 5 to 10 MeV per nucleon energy range, offering a high shunt impedance. The study includes simulations of electromagnetic fields using CST Software, and beam dynamics simulations through a KONUS-type configuration

Speaker: Gabriela Moreno (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas)

14:00 Design of a compact electron linac for the X-ray based intraoperative radiotherapy

In order to fill the gap of X-ray intraoperative radiotherapy technology in China, an X-band standing wave electron linear accelerator with operating frequency of 9.3 GHz was designed for X-ray intraoperative radiotherapy equipment. Using electromagnetic simulation software and beam dynamics simulation software, the outlet energy of the accelerator is 50 keV , and the electron capture efficiency is 37.5 %. The first cavity is 10 mm long for the optimization of the electron beam energy spectrum, and the second cavity is 12 mm long for the electron beam acceleration. The microwave power is distributed to the two cavities respectively through the power divider and the coupler. There is no energy exchange between the two cavities.

Speaker: Hanlin Wan (Lanzhou University)

14:00 Design study for transverse deflecting cavity-based de-chirper

A collaboration is underway to experimentally demonstrate a novel approach using deflecting cavities to control a particle beam’s longitudinal chirp. While a series of deflecting cavities produces negative chirp, the de-chirping process requires additional modification on the beamline. It has been known that inserting negative drift sections between TDCs enables de-chirping. While the original idea of negative drift requires a series of five quadrupole magnets, the experimental conditions cannot provide enough quadrupoles and space for them. Additionally, it is confirmed that a negative drift using three quadrupoles introduces a significant increase in beam size and emittance in one of the transverse planes. Thus, we propose a new method to enable de-chirping by inserting a series of three quadrupoles. Here, we form a negative identity transport instead of the negative drift. Simulations have been performed to explore this new opportunity. We present the result of this design study.

Speaker: Alex DeSimone (Northern Illinois University)

14:00 Development of a pulsed magnet measurement bench using the stretched wire method

In the scope of the renewal of its injection systems, the ESRF-EBS has decided to implement a new scheme using Non-Linear Kickers (NLK) magnets. These pulsed octupole like magnets are extremely sensitive to any misalignment of the conductors carrying the currents resulting in a degraded magnetic field quality. It is then important to characterize precisely the transverse magnetic fields of these magnets to avoid any perturbation during the injection process. A new method to measure pulsed magnetic field is being developed at the ESRF-EBS readapting the classical method of the stretch wire bench for permanent magnet. This paper presents the advancement of this project and the first results.

Speaker: Antonin Sauret (European Synchrotron Radiation Facility)

14:00 Development of the beam separation test device to evaluate the electric field of non-destructive electrostatic septum

Slow beam the extraction in synchrotrons is utilized for various nuclear and particle physics experiments and radiology. A beam loss at a septum electrode induces equipment activation and damage. We have been developing a non-destructive electrostatic septum. This septum has multiple electrodes, and those are placed around the outside of the beam. Measuring the 2-D electric field distribution of this septum is important to evaluate the beam loss reduction due to this septum. We are developing the beam separation test device consists of a prototype septum, horizontal and vertical wire scanners and the electron gun installed on a movable stage fixed to a drive unit. This device measures the electric field by injecting an electron beam into the electric field and measuring the bending angle of the beam orbit. Since the width of the electron beam determines the resolution of the measurement data, we developed an additional lens system that can transport the beam 1.5 m with a width of 1 mm. We used a square chamber for the 2-D measurement system. A permalloy magnetic shield is installed inside the chamber and reduces the external magnetic field from 50 $\mu$T to less than 1.5 $\mu$T.

Speaker: Shota Nagayama (Tohoku University)

14:00 Effects of beam plane correlation on injection efficiency

The effectiveness and efficiency of a beam injection scheme is crucial
to achieve high beam intensities while minimizing possible beam losses.
The classical method for injecting from a linac to a synchrotron is
the multi-turn injection. In this scheme the quality of the injected
beam as well as of the injection scheme depends on factors as beam
emittance, type of local bump ramp, chromaticity, dispersion and beam
intensity. This approach relies on the decorrelation between the
planes of the injected beams. However, investigations on the beam
coming from the linac have suggested the possibility that a beam
correlation may exist*. We present here an investigation of the effect
of a correlated beam on the efficiency of the multi-turn injection for
several degrees of correlation.

Speaker: Annemarie Lauterbach (Goethe University Frankfurt)

14:00 Electron beam scattering in Rubidium vapour at AWAKE

The Advanced Wakefield Experiment (AWAKE) at CERN uses bunches from the CERN SPS to develop proton-driven plasma wakefield acceleration. AWAKE Run 2c (starting in 2029) plans for external on-axis injection of a 150 MeV electron witness bunch. The goal is to demonstrate emittance control of multi-GeV accelerated electron beams. Prior to injection, the electron witness bunch may have to traverse rubidium vapour. Since the beam must have the correct beam size and emittance at injection, it is important to quantify the effect of scattering. For this, first-principle estimates and the results from Geant4 simulations are compared with measurements of a ~20 MeV electron beam scattering in 5.5 m of rubidium vapour, showing good agreement. Building on this agreement, Geant4 simulations using the estimated AWAKE Run 2c parameters are performed. These predict that scattering will not increase the electron beam size or emittance

Speaker: John Farmer (Max Planck Institute for Physics)

14:00 Experimental study on soft X-ray generation via Inverse Compton Scattering at CERN

This study explores the feasibility of using Compton Backscattering (CBS) as a compact source for generating photons in the extreme ultraviolet (EUV) to soft X-ray range, with potential applications in biological imaging and modern lithography. A CBS experiment was conducted at the AWAKE Run 2c test injector (ARTI), where electron bunches, accelerated up to 6 MeV by a high-gradient, brazing-free S-band photogun were collided with 1030 nm infrared pulses from the PHAROS femtosecond laser. The electron and laser beamlines were optimised for maximum CBS photon flux.

Speaker: Vlad Musat (European Organization for Nuclear Research)

14:00 FCC-ee optics tuning studies with pyAT and Xsuite

The FCC-ee is a future high-luminosity circular electron-positron collider aiming at achieving unprecedented luminosities with beam energies ranging from 45.6 up to 182.5 GeV. FCC-ee demands precise optics tuning to achieve its ambitious performance goals. This study investigates the tuning and correction of FCC-ee optics under simulated magnet misalignments, with a particular focus on the stringent initial alignment tolerances required in the Interaction Region (IR). Random misalignment errors were introduced, and correction algorithms were applied to recover the nominal lattice configuration using the pyAT optics framework. Post-correction dynamic aperture studies were conducted to assess the stability and resilience of the lattice under realistic operational scenarios. Benchmarking pyAT outcomes against the Xsuite framework validated the reliability and consistency of the corrections. The study offers valuable insights into alignment tolerance limits, correction methodologies, and their implications for beam dynamics, providing essential guidance for the development and operation of the FCC-ee.

Speaker: Satya Sai Jagabathuni (European Organization for Nuclear Research)

14:00 Higher order mode assessment in a single mode accelerating cavity

With the upgrade from PETRA III to PETRA IV the requirements concerning the beam parameters increase. Thus, a special focus is placed on the suppression of higher order modes (HOMs) in the accelerating systems.
An Investigation of the already presented single mode structure showed the emergence of certain higher order modes. These cavity eigenmodes are now examined by evaluating and assessing their degrading influence on the particle beam by calculating kick and loss factors. Subsequently, the cavity geometry is changed to attenuate the HOMs’ influences or even supress them entirely. In this paper the optimization process using numerical simulations together with the achieved results and cavity structure are presented.

Speaker: Leon Kronshorst (Technical University of Darmstadt)

14:00 Implementation and simulation of a rectilinear cooling channel in BDSIM

Muon colliders offer high-luminosity, multi-TeV collisions without significant synchrotron radiation but require further exploration of muon production, acceleration, cooling, and storage techniques. A proposed 6D cooling demonstrator aims to extend the MICE experiment's validation of transverse ionization cooling to also reduce longitudinal emittance, using bunched muon beams and incorporating RF cavities for reacceleration. The cooling lattice includes solenoids for tight focusing, dipoles for beam dispersion, and wedge absorbers for differential energy loss. This paper presents a complete implementation of cooling channels for BDSIM, a Geant4-based accelerator simulation tool, using appropriate analytic field models to account for fringe-field-dominated magnets. Components have been tested individually and validated against other tracking codes such as G4BeamLine. A tracking study leveraging this implementation is presented, simulating and optimizing a rectilinear cooling channel for the 6D cooling demonstrator. The analysis incorporates beam parameters from existing proton drivers, using outputs from targetry and capture system designs.

Speaker: Rohan Kamath (Imperial College London)

14:00 Improvement of electron beam properties for Few-TW LWFA conducted in a sub-mm gas cell filled with a helium-nitrogen mixture

Developing a laser wakefield acceleration (LWFA) scheme by focusing few-TW laser pulses into a thin, dense gas target paves the way for generating high-average-current electron beams driven by a modern high-repetition-rate laser. Our previous study demonstrated that using a sub-mm nitrogen (N₂) gas cell facilitates the routine generation of 10-MeV-scale electron beams from few-TW LWFA with ionization-induced injection. However, excessive ionization-induced defocusing of the pump laser pulse tends to occur in an N₂ target, motivating the use of a helium (He) – nitrogen (N₂) mixture as the gas target to mitigate pump pulse defocusing in few-TW LWFA*. In this study, the effect of nitrogen doping ratio ranging from 0.5% to 5% was investigated using 40-fs, 1-TW pulses with a 0.4-mm-long gas cell. We found that a manifest peak repeatedly appears around 10 MeV in the energy spectra with the 99.5% He - 0.5% N₂ gas mixture - a result never observed with the pure N₂ cell. Using the He-N₂ mixture also leads to a noticeable increase in the charge of high-energy electrons (>5 MeV) and a reduction in the pointing fluctuation of the output beams compared to the pure N₂ target.

Speaker: Po Wei Lai (National Tsing Hua University)

14:00 Improvement of NSRRC superradiant THz FEL

National Synchrotron Radiation Research Center (NSRRC) has been advancing its capabilities in producing intense terahertz (THz) radiation from a superradiant free-electron laser (FEL). This system utilizes a photoinjector operating in its velocity bunching mode to achieve ultra-short electron bunches. However, the highest THz frequency from the facility is determined by the shortest achievable bunch duration. Currently, the highest THz frequency is limited to 1.4 THz, corresponding to the shortest attainable bunch duration of 240 fsec from the photoinjector. To enable higher THz frequency operation, the NSRRC team is investigating the implementation of a dogleg beamline for enhanced bunch compression. We studied the possibility to generate a 25 MeV electron beam compressed to a 100 fsec bunch duration. Using the PUFFIN code, we have calculated the superradiant THz undulator radiation achievable with these compressed bunches. The results demonstrate the potential to produce intense 3 THz radiation, marking a substantial enhancement in the frequency range and intensity of the THz FEL output.

Speaker: Shan-You Teng (National Central Univeristy)

14:00 Initial characterization of a laser-driven betatron radiation source in the EuAPS project

Betatron radiation is the spontaneous emission of radiation produced by the betatron oscillations of electrons in a plasma during the Laser Wakefield Acceleration (LWFA) process. A high-intensity and ultra-short laser pulse is focused on a supersonic gas jet, simultaneously creating a plasma, injecting, and accelerating electrons, which then emit this radiation. In the framework of the EuPRAXIA project, EuAPS (EuPRAXIA Advanced Photon Source) will be the first user-oriented radiation source based on betatron radiation developed at LNF-INFN Frascati in collaboration with CNR and the University of Rome Tor Vergata.
This radiation source has a wide range of applications, including materials science, medical and biological research. The user facility aims to deliver 1-10 keV photons using a compact laser-driven plasma accelerator operating in a self-injection mechanism, which occurs in highly nonlinear laser-plasma interaction. In this contribution, we present the expected parameters of the source and the result of several dedicated experimental campaigns conducted within the EuAPS project to provide the preliminary characterization of the x-rays betatron radiation source.

Speaker: Federica Stocchi (Istituto Nazionale di Fisica Nucleare)

14:00 Injection simulations of space charge dominated proton beams in IOTA

A 2.5 MeV proton injector is being constructed for the IOTA ring at Fermilab to study the interaction of nonlinear integrable optics (NIO) with high space charge beams. Space charge in the transport line from the RFQ to the injection location has a significant current dependent effect on the phase space. Simulation studies to support efficient injection of intense bunches into IOTA are presented, included schemes to inject directly into NIO lattices.

Speaker: John Wieland (Fermi National Accelerator Laboratory)

14:00 Ion-motion simulations of a plasma-wakefield experiment at FLASHForward

In plasma-based acceleration, an ultra-relativistic particle
bunch—or an intense laser beam—is used to expel electrons
from its propagation path, forming a wake that is devoid
of electrons. The ions, being significantly more massive,
are often assumed to be stationary. However, both theory
and simulations suggest that any sufficiently dense electron
bunch can trigger ion motion, and its effect must be taken
into account. We simulate beam-driven plasma wakefields
to identify key features—such as longitudinally dependent
emittance growth—that could be observed in an experiment
using plasma and beam parameters from the FLASHForward
facility at DESY.

Speaker: Daniel Kalvik (University of Oslo)

14:00 Latest dark current studies of rf photocathode gun of Delhi Light Source

The Delhi Light source is a pre-bunched Free Electron Laser facility to generate coherent THz radiation. The electron beam is generated from a normal conducting 2.6 cell RF photocathode (PC) gun operated at 2860 MHz. The RF gun is powered by a high power RF source for a duration of 4 µs at 10 Hz repetition rate. The dark current during the operation of the RF gun has been found to be substantially high with increasing forward powers (above 3 MW) even after prolonged RF conditioning. Dark current measurements has been done with an in-house developed faraday cup with an objective to understand the possible primary dark current source from locations at the PC that witnesses high accelerating fields. The measurements include the study of solenoid field variation to understand the dark current energies and effect of its steering to understand the possible dark current locations. Simulations to make inference from the measurements has been done assuming different radial position of dark current emitters at the PC surface. The details of the measurements, simulation results and the inference drawn are discussed in the paper.

Speaker: Joydeep Karmakar (Guru Ghasidas Vishwavidyalaya)

14:00 Leveraging the capabilities of LCLS-II: linking adaptable photoinjector laser shaping to x-ray diagnostics through start-to-end simulation

SLAC’s LCLS-II is advancing towards MHz repetition rate attosecond X-ray pulses, creating opportunities to optimize X-ray generation through machine-driven controls and diagnostics via start-to-end simulation. Advanced laser shaping and upconversion techniques at the photoinjector, such as spatial light modulator-based pre-amplifier pulse shaping linked to nonlinear methods such as dispersion-controlled nonlinear synthesis or four-wave mixing, enable precise electron bunch control at the source. Downstream, diagnostics like the Multi-Resolution COokiebox (MRCO)—a 16-channel time-of-flight spectrometer—characterize X-ray pulse profiles, providing real-time feedback on attosecond X-ray pulses or attosecond X-ray substructure. We present developments towards a framework linking programmable photoinjector laser shaping to X-ray diagnostics, enabling data-driven optimization of the X-ray source. This approach combines machine learning, high-throughput feedback, and advanced control to align LCLS-II capabilities with experimental goals, laying the foundation for optimization of attosecond-scale precision in X-ray experiments.

Speaker: Jack Hirschman (Stanford University)

14:00 Low-power test of bridge coupler 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 electric dipole moment (EDM). A 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 is currently being fabricated and will be tested. This paper presents the design and performance evaluation of the bridge coupler prototype.

Speaker: Ayaka Kondo (Nagoya University)

14:00 Low-temperature and strained-lattice effects on Monte Carlo modeling of spin-polarized photoemission from GaAs

The degree of spin-polarization of electrons photoemitted from unstrained, room-temperature GaAs is usually significantly less than the theoretical maximum of 50%. However, it has been experimentally observed that the degree of electron spin polarization can be increased and even exceed the theoretical maximum when the sample is cooled to low temperatures and in strained-lattice samples. The previously developed Monte Carlo approach to spin-polarized photoemission from unstrained, room temperature NEA GaAs provides excellent agreement with experimental data in a wide range of doping densities and photoexcitation energies. This work aims to extend the model’s capabilities by incorporating both low-temperature and strained-lattice effects into the band structure and investigating their impact on spin and momentum relaxation mechanisms. Modeling of both low-temperature and strained NEA GaAs with the use of parameters obtained via Density Functional Theory (DFT) calculations will provide a foundation for modeling photoemission from novel spin-polarized materials and complex layered structures and aid in the discovery of new cathode materials.

Speaker: John Callahan (Northern Illinois University)

14:00 Machine learning approach to MDI optimization for 3 TeV c.o.m. Muon Collider

The Muon Collider is a proposed future accelerator for very high energy muon collision. Since muons are heavier than electrons, the synchrotron radiation is negligible at this high energy, allowing to build a compact machine able to deliver Multi-TeV c.o.m. energy collisions, enabling precision measurements of the Standard Model quantities and search for new physics. A challenge of a muon beam is the Beam-Induced Background (BIB), a flux of particles in the detector generated by secondary interaction of muon decay products with the accelerator components.
To deliver the required physics performance, the Machine Detector Interface design needs to include a shielding for the BIB. The proposed solution consists of cone-shaped tungsten shields inside the detector area. The nozzles reduce the BIB to a manageable level at the cost of reducing the detector acceptance. A careful optimization of the geometry is necessary to further mitigate the BIB and improving the detector acceptance to maximize the physics potential. This contribution aims at discussing the optimization achieved with machine learning algorithms in combination with FLUKA simulations for a 3 TeV c.o.m. Muon Collider.

Speaker: Luca Castelli (Sapienza University of Rome)

14:00 Modelling optics and beam-beam effects of SuperKEKB with Xsuite

SuperKEKB, located at KEK, is a second generation B-factory, providing beam to the Belle-II experiment. Optics design and simulation of SuperKEKB were previously performed using the optics code SAD, developed at KEK. In this paper, we present a new model of SuperKEKB using the tracking code Xsuite, developed at CERN. An alternative strategy for modelling the interaction region, with controllable final focus quadrupoles, has been adopted. Optics comparisons between the new Xsuite model and existing SAD model, as well as tracking simulations including beam-beam modelling are presented.

Speaker: John Salvesen (European Organization for Nuclear Research)

14:00 Multi-physics analysis of a 280 MHz superconducting radio-frequency quadrupole test cavity

Superconducting(SC) radio-frequency(RF) quadrupole (RFQ) integrates the high efficiency of SC technology with the strong focusing and stable acceleration capabilities of RFQ .It is a critical development in next-generation high-performance accelerators.In this study, we present the multi-physics analysis results of a SC RFQ test cavity operating at a frequency of 280 MHz. This test cavity is designed to be a constant voltage of 240 kV and can be used to accelerate a 10 mA proton beam. The RF design adopts a four-vane structure, which is both structurally stable and facilitates efficient liquid helium cooling. Multi-physics analysis indicates that the cavity deformation and thermal stress meet the operational requirements after the post-treatment of the electrodes.The SC RFQ holds significant potential in many areas, including medical isotopes,particle physics experiments,Boron Neutron Capture Therapy (BNCT) and Proton Therapy. Because of the low operational costs and compact structure, it provides an possibility to enable industrialization and applications of high-power accelerators.

Speaker: Junzhao You (Peking University)

14:00 Numerical simulation of on-axis helical undulator radiation using SCILAB-Xcos model

Abstract—A SCILAB Xcos model, developed using SCILAB software version 6.1.1, was implemented to simulate the on-axis radiation intensity of a helical undulator, (undulator parameter= 1, undulator wavelength 5cm, number of periods= 10, device length 0.6 m) with an electron beam (1, 2, & 3 GeV) and beam current as Ib = 3–6 × 10⁻⁶ Ampere. A numerical approach is utilized to perform the undulator radiation intensity calculations. The computed results were validated by comparing the on-axis undulator radiation intensity with those obtained from SPECTRA, an open-source synchrotron radiation (SR) calculation software.

Speaker: Ms Mahazbeen Sayed (Rajiv Gandi Proudyogiki Vishvidhyala)

14:00 Operational deployment of automatic angular alignment for LHC collimators

The Large Hadron Collider (LHC) features a collimation system that protects the machine against beam losses that may induce the loss of superconductivity in some exposed lattice magnets. Thus, optimal cleaning performance must be ensured at all times. The collimation system encompasses more than 100 collimators whose settings are organised in a well-defined transverse multi-stage hierarchy. A collimator alignment toolset has been developed over the years to automate the alignment of the system during beam commissioning. During alignment, the collimator jaws used to be kept parallel to the central beam orbit. However, further tightening of the collimation hierarchy to improve the β* reach is only possible if the collimator jaw angles are precisely adjusted to compensate for any mechanical or orbit tilts. Advanced alignment procedures have therefore been developed to compensate for these effects. The first operational deployment of jaw angle has been achieved in the 2024 run. The commissioning results leading to this milestone are reported in this paper, together with the optimisation of parallel jaw alignment and an overview of the operational architecture.

Speaker: Andrea Vella (University of Malta)

14:00 Optimisation of drift tube cooling and drift tube geometries of an additive manufacturing IH-type cavity

Additive manufacturing is a now-powerful tool for the rapid prototyping and manufacturing of complex geometries. A proof-of-concept 433 MHz IH-DTL cavity was constructed for direct additive manufacturing of linear accelerator components. The CFD analysis of the initially designed cooling for the drift tube revealed a design with insufficient heat dissipation; this can lead to thermal deformations as well as problems in keeping the frequency stable during operation. In this respect, an optimization of the cooling system was done in detail with the help of advanced thermal simulation and iterative design improvements.
Furthermore, the geometries of the drift tubes were refined to improve mechanical stability and thermal efficiency without compromising electromagnetic performance. The results illustrate that additive manufacturing can achieve significant design freedom, enabling new approaches toward the thermal management challenges faced by high-frequency linear accelerator components.

Speaker: Benjamin Dedic (Goethe University Frankfurt)

14:00 Optimization of the Driver Energy Deposition in Plasma Wakefield Acceleration Simulations by Varying Transverse Offset of Sextupole Magnets

Plasma Wakefield Acceleration (PWFA) is a method of accelerating charged particles using a plasma. It has the potential to produce exceptionally large accelerating gradients on the order of 10’s of GeV/m. The FACET-II test facility accelerates pairs of 10 GeV electron bunches to study the PWFA process—a drive bunch to produce a wake in the plasma in a lithium-ion oven, and a witness bunch to be accelerated by PWFA. By using arrangements of sextupole magnets, it is possible to alter the chromaticity and other energy-dependent properties of the beams prior to their entry into the plasma. The purpose of this study was to determine how the transverse offsets of the sextupole magnets could be optimized to increase the amount of energy deposited into the plasma by the drive bunch as this energy deposition is critical to maximising the efficiency of PWFA. To achieve this, a simulation of the FACET-II beamline was performed with sextupole offsets as adjustable parameters in a Bayesian Optimization procedure. The results demonstrate the value of using beam simulations as guides to improve the PWFA process, thereby reducing the need to perform costly experiments at the FACET-II facility.

Speaker: Mason Stobbe (SLAC National Accelerator Laboratory)

14:00 Optimizations for enhancing performance of emittance exchange-based photoinjector

A recent simulation study demonstrated the potential to achieve high 4D-emittance using an emittance exchange (EEX) beamline integrated within a photoinjector. This EEX beamline enabled to achieve the final normalized longitudinal emittance of 0.44 micron, which corresponds to rms bunch length of 7micron and energy spread of 32keV. These results are noteworthy for a 60-MeV photoinjector comprising a gun, linac, and EEX beamline. However, the transverse emittance of approximately 0.6 micron remains a limitation for many applications. To address this, we have conducted computational studies to improve the performance of EEX photoinjector. We present the progress achieved thus far.

Speaker: MinKyu Seo (Korea University Sejong Campus)

14:00 Optimizing cavity detuning at high beam intensities in the LHC

The increased beam intensity during the high lumionsity LHC era is expected to impose tight margins on the operation of the LHC RF system. The larger momentum spread from the injectors together with twice the bunch charge requires a higher RF voltage at injection to avoid beam losses. However, the peak RF power due to the increased beam loading must be kept below the saturation level of the klystrons. Accurate optimization of RF parameters is therefore needed to maintain a sufficient RF voltage to capture and retain the injected beam. In the LHC, the beam-loading is partially compensated by detuning the RF cavities. This is achieved at injection by a pre-detuning scheme and throughout the injection plateau by applying half-detuning. During the 2024 run the pre-detuning was adjusted with beam to minimize the required peak power at injection. Furthermore, a new algorithm was developed to optimize the setup of the half-detuning scheme at a given bunch intensity. Both measures have been essential to accommodate higher beam intensities in the LHC.

Speaker: Birk Emil Karlsen-Bæck (European Organization for Nuclear Research)

14:00 Positron Contamination in the Muon Beam at the J-PARC's Surface Muon Beamline (S-line)

The surface muon beamline at J-PARC provides high-intensity muon beams that are essential for advanced materials science research, particularly in techniques such as muon spin rotation/relaxation (μSR). However, positron contamination in the beam poses a significant challenge by introducing background noise that affects the measurement precision. Therefore, achieving high-purity muon beams is critical for improving experimental reliability and accuracy. In this study, the G4beamline Monte Carlo simulation toolkit was employed to model the transport of muons and positrons from the production target through the beamline. The system includes a momentum and charge-based separator followed by a collimating slit. While the current slit configuration effectively suppresses positrons, it also causes substantial muon loss of approximately 76%, which significantly reduces the usable muon flux for downstream applications. To address this issue, a detailed investigation into slit size was performed. The results indicate that modest adjustments to the slit aperture size can improve the muon-to-positron ratio while retaining a greater fraction of the muon beam. These results provide valuable guidance for optimizing beamline performance and improving the quality of muon-based experiments at J-PARC.

Speaker: Phanthip Jaikaew (RIKEN Nishina Center)

14:00 Pulsed Compton gamma-ray beam generation using pulsed FEL beam

Gamma-ray induced nuclear physics experiments rely on good signal-to-noise ratio, requiring accurate rejection of detector background. One source of this background is the interaction of cosmic rays with nuclear detectors. The Duke High Intensity Gamma-ray Source (HIGS) is typically operated in quasi-CW mode, requiring background measurements to be conducted independently of data production runs. A pulsed mode of HIGS beam operation enables improved rejection counts by allowing time discrimination between detector counts in coincidence with the gamam beam and detector counts out of coincidence with the beam.

To achieve a HIGS beam with good pulse quality, a fast steering magnet has been used to decouple the FEL beam from the HIGS beam in the interaction region. By periodically overlapping the electron and FEL beams, gamma production can be limited to only the periods of overlap. Gating on these gamma pulses has been shown to reduce signal to noise ratio by at least 3 orders of magnitude.*,*,** However, this technique produces poor results at low energies, requiring development of more sophisticated gating techniques.

Speaker: Stephen Yates (Triangle Universities Nuclear Laboratory)

14:00 RF design of the positron traveling-wave structure

The Super Tau-Charm Facility (STCF) is a new generation of electron-positron colliders being planned with a design center of mass energy of 2-7 GeV. In the concept design, the positrons produced by electron targeting are accelerated to an energy of 200MeV by three large-aperture accelerating structures, and then to 3.5GeV by several conventional accelerating structures. The aperture of large-aperture accelerating structures is maintained constant, and the group speed is controlled solely by adjusting the length of the nose cone for easier production. Pulse compressors are taken into account to increase the accelerating structures power. In this paper, the designs of 2m and 3m large-aperture accelerators are presented, both achieving gradients higher than 15 MV/m.

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

14:00 Simulated beam performance of the TWOCRYST proof of principle experiment at the LHC

TWOCRYST is a machine test designed to demonstrate the feasibility of an in-vacuum fixed-target experiment for the first direct measurement of the magnetic and electric dipole moments of short-lived charm baryons. This setup exploits crystal channeling using two bent crystals. The first one is similar to the existing crystals used in the LHC for beam collimation, deflecting the beam halo particles from the proton beam onto a target. The second one - a 7 cm silicon crystal - induces spin precession in the secondary particles produced in the target. 2D detectors in movable Roman pots will track the distribution of these channeled particles. A new silicon pixel detector and a fiber tracker (formerly used by the LHC ATLAS-ALFA experiment) are planned for installation in the LHC along with the two crystals in early 2025. Xsuite simulations have been performed to reproduce the multi-turn beam dynamics of the channeled beam halo and the particle distribution expected at the detectors. The LHC configurations required for the planned measurements have also been simulated, with the results used to specify the required detector performance in preparation for benchmarking against real data.

Speaker: Chiara Maccani (European Organization for Nuclear Research)

14:00 Simulation and developmental status for generation and detection of THz using coherent transition radiation (CTR) technique in Delhi Light Source (DLS)

THz technology being a highly growing and potent field, finds use in a wide range of research applications. Delhi Light Source (DLS) at IUAC, New Delhi is at final stage of commissioning to produce intense and coherent THz radiation based on pre-bunched Free Electron Laser principle. As an addition to the narrowband undulator radiation, broadband Coherent Transition Radiation (CTR) will also be produced by passing femtosecond electron beam bunches through an Al foil . To generate the electron bunches with multi-micro bunch structure from the RF photo cathode gun, a state of the art femtosecond fiber laser system has been developed in collaboration with KEK, Japan. The generated electron beam bunches with energy up to 8 MeV is expected to produce CTR maximum up to few microjoule of energy. The multi-micro bunch structure increases the average CTR power. This paper reports the simulation results of the CTR showing the power, angular and frequency distribution produced from DLS facility. The schematic design and developmental status of DLS for generation and detection of THz CTR are also discussed.

Speaker: Bappa Karmakar (Inter-University Accelerator Centre)

14:00 Simulation and optimization of a sub-THz Cherenkov FEL at AREAL

A circular waveguide lined with a thin dielectric layer enables electron bunches propagating within the structure to radiate light in the (sub-)THz regime. In this work, we perform simulations of low-energy electron beams traversing extended waveguides to analyze the dynamics of beam bunching and lasing within the structure. By exploring the free-electron laser (FEL) process in this context, we demonstrate the potential of waveguides as a cost-effective alternative to undulator-based FELs. The study employs a simulated model of the AREAL LINAC at the CANDLE SRI to demonstrate these effects and provide realistic results. The simulations are performed using the space charge tracking algorithm ASTRA and the wakefield solver ECHO. For optimization of the system, the genetic optimization algorithm GIOTTO is applied to refine both the waveguide and accelerator variables. Using a 4 MeV electron beam with a charge of 300 pC, the optimized setup achieves a radiation frequency of 100 GHz with energy outputs exceeding 20 µJ in a waveguide of only 1.2 meters length. These results underscore the feasibility of this method, offering a innovative pathway to produce intense THz radiation.

Speaker: Karel Peetermans (Deutsches Elektronen-Synchrotron DESY)

14:00 Simulation study of nanostructured plasmonic copper photocathodes

We present an electromagnetic characterization and beam dynamics study of nanostructured plasmonic copper photocathodes for electron gun applications. The study concentrates on photocathodes operated at ultraviolet and infrared wavelengths. Various types of nanopatterns are explored in order to understand how different geometrical parameters affect light reflectance. Optimized nanostructure geometries show significant plasmonic field enhancement, leading to improved photon absorption and increased quantum efficiency at the target laser wavelength. The results of electromagnetic simulation are used to obtain quantum efficiency spatial distribution on the structured cathode surface. The resulting distribution is used for optically induced emission simulation. Beam dynamics simulation results of the photoemitted electron bunch in the vicinity of the nanostructured cathode are presented, analyzed, and compared to those of a flat photocathode.

Speaker: Margarita Bulgacheva (Technical University of Darmstadt)

14:00 Simulations of losses from fast instabilities in the FCC-ee

The electron-positron Future Circular Collider (FCC-ee) is a proposed high-energy lepton collider that aims to reach unprecedented luminosity and precision in the measurement of fundamental particles. To fully profit of such performance, it is crucial to keep detector backgrounds under control and operate the machine safely. Due to the high stored beam energy and to a number of complex operational features required at FCC-ee (e.g. the top-up injection scheme), controlling the backgrounds to the physics experiments becomes even more challenging. Recent studies on collective effects have shown that high impedance in the FCC-ee can lead to fast rise-time instabilities, where the beam amplitude grows exponentially, leading to beam loss within a few turns. Although a feedback system is being developed to mitigate this instability, failure scenarios of this feedback system need to be explored. This paper presents the study of the effects of this instability, in order to understand the possible implications for the machine and the experiments.

Speaker: Giulia Nigrelli (European Organization for Nuclear Research)

14:00 Simulations of transverse dynamics in a laser-plasma accelerator

Laser Wakefield Accelerators (LWFA) offer a promising solution for producing high-energy electron beams in compact setups. Beyond obtaining the required energy, the beam quality (emittance, energy spread, intensity) must also be optimized for LWFA to be considered an alternative to conventional accelerators. Achieving precise control of the transverse beam dynamics is one of the key challenges. This article thoroughly studies the physics governing the evolution of emittance and Twiss parameters within the plasma stage, on the density plateau, and in the up-ramp and down-ramp connections to conventional transport lines. Analytical and numerical analysis will be conducted using a toy model made of special quadrupoles, allowing numerical calculations to be sped up to a few seconds/minutes. Matching between plasma and transport lines will be extensively studied, clearly showing the dependence on initial conditions, and recommendations for the best realistic configurations will be provided*.

Speaker: Laury Batista (Commissariat à l'Énergie Atomique et aux Énergies Alternatives)

14:00 Simulations study of transverse wakefields in a dielectric wakefield acceleration scheme

Novel acceleration schemes aim to address the need for higher acceleration gradients which enable to minimise the size and costs of particle accelerators. One of these novel accelerator schemes is the dielectric wakefield acceleration (DWA), where an electron bunch is accelerated by the longitudinal wakefields generated within a dielectric lined waveguide by a leading drive bunch with higher charge. The advantages of this novel acceleration method include high accelerating field strength, the simplicity of its structure and the stability of the wakefield generated which is synchronous with the electron bunch. However, the drive bunch propagation length, and hence the achievable energy gain, is limited by the effect of the transverse wakefields. These fields deflect the bunch towards the dielectric, leading to charge losses, a phenomenon commonly referred to as beam break-up (BBU) instability. This study uses simulations to investigate the transverse wakefields and their impact on the beam dynamics in a DWA scheme with drive and witness (main) bunches. The findings will be further explored experimentally at the CLARA facility in Daresbury Laboratory.

Speaker: Beatriz Higuera Gonzalez (Cockcroft Institute)

14:00 Single electron storage at UVSOR-Ⅲ electron storage ring

We have started single electron storage experiments since 2021 at the UVSOR-Ⅲ storage ring with the aim of conducting fundamental research on electromagnetic radiation. At BL1U, which is a beamline dedicated to light source developments, we extracted undulator light in the UV wavelength range into the air and observed its intensity by a photomultiplier tube, as decreasing the electron beam intensity using a beam scraper. When the beam intensity became sufficiently small, we observed step-function-like intensity changes with a good SN ratio, each of which corresponded to a loss of one electron. Based on this technique, we confirmed the single electron storage. After establishing the technique, we conducted some experimental studies on undulator radiation from single electron. We will present the latest results at the conference.

Speaker: Yuya Asai (Hiroshima University)

14:00 Six-dimensional phase space reconstruction with multimodal CNN

The information on phase space in all six dimensions is required for various accelerator experiments. We developed an algorithm based on Convolutional Neural Network (CNN) that can be used instead of the traditional back projection techniques because it is less computationally intensive and has a simple architecture. Our method has shown consistency with the simulation, and we plan to validate it on data taken at the KEK–Superconducting Test Facility (STF).

Speaker: Sayantan Mukherjee (Hiroshima University)

14:00 Solid-state driven X-band linac for electron microscopy

Transmission Electron Microscopes (TEM) require high voltage DC electron sources, which can quickly grow in size and cost at the higher energies required for standard TEM imaging. We present the progress on a low cost, compact solid-state-driven RF linac to replace high power electron guns in micro-crystal electron diffraction setups. The system accelerates electrons to 50 keV electrons with a 4 cell standing wave structure, where each cell is individually powered by an X-band solid-state amplifier. Future expansions on this design could function as a compact (order of 1 meter) source of electrons up to 1 MeV.

Speaker: Julia Sherman (Wellesley College)

14:00 Spatial polarization distribution measurements of gamma rays produced by inverse Compton scattering

Highly polarized MeV gamma rays, produced by Laser Compton Scattered (LCS) of a polarized laser with an electron beam, offer a unique probe for basic and applied physics research. As the polarization characteristics of these gamma rays vary with the position of the beam cross section, it is essential to understand the polarization properties when using polarized gamma rays * . However, detailed measurements of the two-dimensional spatial polarization distribution have not yet been conducted. In the UVSOR synchrotron facility, a polarimeter was developed to measure the spatial polarization distribution of linearly polarized gamma rays. The polarimeter is based on asymmetry measurements of the Compton scattering cross section. In this conference, we will report on measurement results of the spatial polarization distribution of linearly and circularly polarized LCS gamma-rays. The polarization axis of the polarized gamma rays was clearly measured to vary with scattering and azimuth angle. In the near future, we plan to use the developed polarimeter to also measure the spatial polarization distribution of gamma rays generated by an axially symmetric polarized laser ** .

Speaker: Yuxuan Yang (Zhengzhou University, Institute for Molecular Science, Shanghai Institute of Applied Physics)

14:00 Spectrum-based alignment of SIRIUS undulators

Recently, two SIRIUS beamlines, EMA and PAINEIRA, received their definitive insertion devices (IDs). Both IDs are in-vacuum devices (IVUs), the first of this kind at SIRIUS. Due to the proximity of the IVU cassettes to the electron beam, the spectrum emitted by these devices is highly sensitive to misalignments of the ID magnetic center. Such misalignments can result in photon flux losses, spectral shifts toward lower energies, and broadening of the resonance. This work presents the application of O. Chubar’s* spectrum-based alignment method to one of the new SIRIUS IVUs, aiming to optimize its performance at the beamline.

Speaker: Gabriel Ascenção (Brazilian Synchrotron Light Laboratory)

14:00 Spill optimization system for improving slow extraction at GSI

Resonant slow extraction is routinely used to provide ion beams to various users. At GSI SIS18, two extraction methods are implemented: quadrupole-driven and Radio Frequency Knock Out (RF-KO) extraction. In either case, delivering a defined beam intensity (spill) without fluctuations or drifts is desired for an efficient beam usage. The Spill Optimization System (SOS) was developed to address this demand and improve the spill quality based on online spill monitoring. Implemented using software-defined radio technology, it comprises a feedback controlling the spill rate and an optimization algorithm to improve the spill quality. In the case of RF-KO extraction, it controls the spill by generating tailored excitation signals for the KO exciter. For quadrupole-driven extraction, it produces a control signal for the tune ramp including tune wobbling to improve the spill quality. This contribution gives an overview on the systems and compares different usage scenarios.

Speaker: Philipp Niedermayer (GSI Helmholtz Centre for Heavy Ion Research)

14:00 Steady-state response matrix of radio-frequency cavity voltage in storage rings

The study of beam-cavity interaction is an essential step towards achieving the design objectives of high-intensity storage rings, particularly in the rapidly advancing fourth generation of synchrotron light sources, which rely on the strategy of bunch lengthening with harmonic cavities. Assessing the effectiveness of harmonic cavities typically requires self-consistently solving bunch equilibrium distributions, accounting for beam-loading voltages. This paper introduces a novel concept of the steady-state response matrix (SSRM) of radio-frequency (RF) cavity voltage: the steady-state beam-loading voltages are expressed as a product of the SSRM and an array containing only the information in bunch charge density distributions. Notably, the SSRM depends solely on RF cavity parameters such as R/Q, loaded Q, and resonant frequency. We demonstrate that the SSRM can significantly simplify and accelerate the self-consistent calculation of bunch equilibrium in double RF systems. Additionally, the SSRM can also facilitate the calculation for transient beam-loading feedforward compensation and the evaluation of thresholds for periodic transient beam-loading effect.

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

14:00 Study of the coherent < x-z > instabilities for FCC-ee

This work examines the dominant coherent head-tail type (< x-z >) instabilities in the vertical plane of the FCC-ee collider, focusing on a mode analysis method with the Circulant Matrix Model (CMM) to assess instability mechanisms under the influence of beam-beam effects and transverse wakefields. While the impact of vertical plane instabilities have been already studied, different mechanisms are prominent in the horizontal plane. Understanding these mechanisms is crucial to identifying a stable working point at the Z energy. This study aims to advance the stability analysis and optimisation of FCC-ee at Z energy by investigating horizontal plane dynamics. Our findings indicate that mitigation strategies effective for vertical plane instabilities may not be sufficient and need to be adapted in order to ensure overall beam stability.

Speaker: Roxana Soos (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

14:00 Study of the phase jump method for FEL oscillator

We propose a phase jump method to improve the electron beam conversion efficiency in FEL oscillator. A fast phase shifter is put between two undulator segments to kick the phase of the electron beam at saturation. The theoretical and simulation results are given based on FELiChEM which is built in Hefei. They indicate that a phase jump value of approximately π at saturation can significantly increase the gain and thus improving the FEL power. Taking 30μm wavelength as an example, the output power is increased by about 2.75 times than before.

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

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 radiation performance of circular polarization in traditional APPLE-KNOT undulator

The traditional APPLE-KNOT undulator forms composite magnetic fields by superimposing APPLE fields and KNOT fields with the period ratio of 2:3. The APPLE field serves as the main component to approximate the target photon energy, while the KNOT field acts as an additional component to transversely deflect the electron beam away from axis. Variable polarization states can be generated with a low on-axis heat-load in the APLLE-KNOT undulator. Compared the traditional APPLE-KNOT undulator with the APPLE II undulator, a sharp reduction on flux of circular polarization state can be observed. In this paper, this phenomenon is detailed discussed from the theoretical perspective. It indicates that a larger period length of KNOT field than APPLE field with a strong field contribution of KNOT field will greatly suppress the flux of circular polarization state, which is highly consistent with the simulation result. To keep a good performance both at the linear and circular polarization states with little on-axis heat load, the period ratio and field amplitude ratio between APPLE and KNOT fields should be comprehensively optimized.

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

14:00 Studying photoemissive properties of stable Cs-Sb compound thin-film photocathodes using a combination of Monte Carlo simulations and Density Functional Theory

Cs-Sb compound thin-film photocathodes are an excellent candidate to produce bright electron beams for use in various accelerator applications. Despite the virtues of these photocathodes being known, the mechanics that govern their promising photoemission are not well-understood. Crystalline and other material properties affect the quantum efficiency (QE) as well as mean transverse energy (MTE) and, therefore, the overall brightness. In addition, electrons photoemitted from these thin films experience an unexpected energy loss similar to that found in bulk crystals despite their being a significantly shorter transport phase. Deeply understanding the relationship between the crystalline properties and the emitted electron beam’s brightness, as well as this drop in energy, is vital to generating ultra-bright electron beams for advanced accelerator applications. The purpose of this work is to use the Monte Carlo method to simulate photoemission from semiconducting films with electronic band structure parameters supplied by Density Functional Theory (DFT) calculations. This method is used to study all three steps of photoemission and to identify the key parameters necessary for optimizing photocathode performance.

Speaker: Daniel Franklin (Northern Illinois University)

14:00 Suppression of bunch destruction under resonant excitation of the wakefield

Acceleration by the wakefield in the plasma can provide compact sources of relativistic electron beams of high brightness. Free electron lasers and particle colliders, using plasma wakefield accelerators, require high quality bunches with predictable profile. Previous studies showed that the resonant sequence of electron bunches appears to be unstable due to the destruction of the bunches. In this paper we discuss the mechanism of this destruction due to the focusing field phase shift which appears during this time evolution. We numerically and analytically showed the possible way of suppressing this instability, shifting all bunches on some distance.

Speaker: Ilia Demydenko (V. N. Karazin Kharkiv National University)

14:00 Synthesis of efficient ordered sodium potassium antimonide photocathodes via molecular beam epitaxy

Alkali antimonide photocathodes exhibit high efficacy as photoemissive materials in electron sources. This proceeding explores the fabrication of thin, ordered films of sodium potassium antimonide via molecular-beam epitaxy (MBE) at the PHotocathode Epitaxy Beam Experiments (PHOEBE) laboratory at Cornell University. Utilizing a sequential deposition technique, the photocathodes are characterized in terms of both quantum efficiency (QE) and crystal structure with the goal of reducing the chemical and physical roughness. A spectral response from 400 to 700 nm demonstrates oscillations resulting from optical interference within the (SiN) substrate. Reflection high-energy electron diffraction (RHEED) patterns confirmed the successful growth of ordered crystal structures for the first time in a sodium potassium antimonide photocathode. Additionally, we investigated the photocathodes' sensitivity to oxidation, revealing their relative robustness compared to CsSb or KSb photocathodes. Notably, the incorporation of higher partial pressures of oxygen during growth improved QE and extended the operational lifetime of the photocathodes.

Speaker: Abigail Flint (Cornell University (CLASSE))

14:00 Tapering enhanced superradiance - tapering rate optimization using analytical magnetic field maps

THz sources are typically very limited in power, making high-power sources scarce. One of the most promising THz sources are the Free Electron Lasers (FELs), which can generate high-power THz radiation using an undulator structure. Undulator radiation is an incoherent synchrotron spontaneous emission whose energy is proportional to the number of particles in the beam (𝑁). By longitudinally bunching the charged particle beam, a coherent spontaneous emission is generated and referred to as a super-radiant emission. Unlike spontaneous emission, super-radiant energy yield is proportional to N^2.
However, like typical FELs, the energy conversion efficiency is rather low. Here, we demonstrate a novel THz source structure based on a radiative interaction scheme of super-radiance – Tapered Enhanced Super-radiance (TES), which employs a tapered (amplitude) undulator in the zero-slippage condition. This method yields a significantly more powerful and efficient THz radiation source. An optimization algorithm was developed to obtain a tapering rate that yields the most efficient energy conversion from the electron beam to the radiation field.

Speaker: Leon Feigin (Ariel University)

14:00 The high harmonic radiation with mild energy modulation based on storage ring

The synchrotron radiation generated by storage rings offers numerous advantages, including high stability, a broad photon energy range, and the capacity to support multiple users simultaneously. However, one notable limitation is its poor radiation coherence. Achieving coherent harmonic generation (CHG) in storage rings would not only significantly enhance the coherence of the emitted light but also dramatically improve specific spectral ranges, internal luminous flux, brightness, and energy resolution. However, the realization of higher order harmonic radiation usually requires higher energy modulation. In this paper, a relatively mild energy modulation scheme is proposed to generate higher harmonic radiation based on storage rings. Lower energy modulation is achieved by using a lower power laser, and then an additional self-modulation section is introduced to enhance the bunching factor of harmonics. Three-dimensional time-dependent simulation results based on the parameters of Hefei light source-II show that the modulation amplitude is reduced by half under the same harmonic radiation power, which can greatly improve the tolerance of the modulation to the momentum aperture in the ring and reduce the damping time to achieve coherent radiation with higher repetition rate.

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

14:00 The physical design for High-Repetition-Rate IR-THz FEL

The field of Free-Electron Lasers (FELs) has matured, with advancements prioritizing high repetition rates, full coherence, and an expanded wavelength spectrum. This paper details the establishment of a high-repetition-rate Infrared Terahertz (IR-THz) Free-Electron Laser (FEL) facility at the Hefei Comprehensive National Science Center. This facility is strategically integrated with the existing HALF light source, forming a cohesive low-energy synchrotron radiation and FEL facility cluster that amplifies research capabilities. We present an innovative approach to optimizing microwave parameters within the linear acceleration section, employing a custom MATLAB program developed in-house. This method enables meticulous control over the beam current profile, ensuring the generation of high-quality beams tailored for FEL applications. Through the utilization of advanced software such as ASTRA and CSRTrack, we have executed comprehensive beam dynamics simulations and calculations, successfully achieving beam quality that aligns with the stringent requirements of FEL applications.

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

14:00 Towards lossless beam transmission in the first LHe-free Nb₃Sn SRF e-linac

Superconducting radio-frequency (SRF) electron linear accelerators (e-linacs) provide significant advantages over conventional room-temperature accelerators, especially in their capacity to accelerate high-intensity continuous-wave (CW) beams. Recently, the first liquid helium-free (LHe-free) Nb₃Sn SRF cavity was successfully operated at the Institute of Modern Physics of the Chinese Academy of Sciences (IMP, CAS), achieving 5 MeV, 200 mA CW beam acceleration and demonstrating the feasibility of miniaturized SRF e-linacs. However, the lack of time structure in the injected beam and its velocity mismatch with the cavity's optimal beta value lead to approximately 50% beam loss within the SRF cavity, presenting a critical challenge for long-term operation. This paper presents an upgrade design of the existing e-linac, ensuring 100% transmission in the SRF cavity while maintaining a compact configuration. Detailed beam dynamics design and multi-particle simulation results are discussed.

Speaker: Yimeng Chu (Institute of Modern Physics, Chinese Academy of Sciences)

14:00 Transverse stability of multiple trailing bunches in filament-regime plasma wakefield acceleration

Plasma wakefield acceleration in the filament regime can provide wakefields suitable for high-gradient, high-quality positron acceleration while maintaining stability. However, the energy that can be extracted by the positrons is limited. Recent works have proposed accelerating a supplementary electron recovery bunch along with the positron bunch to extract more energy from the wake and improve the overall transfer efficiency during acceleration. However, it is unclear if such energy recovery schemes are stable when subject to misalignment. In this work, we employ quasi-static particle-in-cell simulations to study the transverse stability of configurations involving three bunches.

Speaker: Rafael Yrjosmiel Legaspi (Mapúa University)

14:00 Updated monochromatization Interaction Region optics design for FCC-ee GHC lattice

Determining Yukawa couplings of the Higgs boson is one of the most fundamental and outstanding measurements since its discovery. The FCC-ee, owing to its exceptionally high-integrated luminosity, offers the unique opportunity to measure the electron Yukawa coupling through s-channel Higgs production at 125 GeV centre-of-mass (CM) energy, provided that the CM energy spread can be reduced from 50 MeV to a level comparable to the Higgs bosons’ natural width of 4.1 MeV. To improve the energy resolution and reach the desired collision energy spread, the concept of a monochromatization mode has been proposed as a new operation mode at the FCC-ee, relying on the Interaction Region (IR) optics design with a nonzero dispersion function of opposite signs at the interaction point (IP). A first optics design and preliminary beam dynamics simulations have been carried out for version 22 of the FCC-ee GHC lattice type. In response to the continuously evolving FCC-ee GHC optics, this paper presents an optimized updated monochromatization IR optics design based on the Version 2023 of the FCC-ee GHC optics.

Speaker: Angeles Faus-Golfe (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

14:00 Wafer-compatible photocathode plug design for high gradient RF photoinjector

Single crystal alkali antimonide photocathodes have been shown to produce brighter beams than their polycrystalline counterparts. These single crystal semiconductors require a lattice matched substrate to be grown, but current INFN plugs lack the capability for this growth. To relieve this issue, we modified the INFN plug to hold a disk 1cm in diameter. This allows for studies of a wide range of advanced photocathodes and geometries on arbitrary substrates in high gradient photoinjectors. We show the modified design, analysis of the local field at the cathode and cavity detuning, and demonstrate the principle with a 1cm Yttrium disk.

Speaker: David Garcia (Particle Beam Physics Lab (PBPL))

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-ray domain to achieve 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 → 18:00 Student Poster: SUPS

14:00 A TM020-mode cavity with choke geometry for Super Tau-Charm Facility

A compact TM020-mode radiofrequency (RF) cavity has been proposed and studied by KEK and RIKEN for storage ring of Nanoterasu facility. However, the leakage power of the accelerating mode into the coaxial slots is an issue to limit its performance. This paper presents an improved TM020-mode cavity in order to solve this issue. To protect the operating mode and reduce its leak-age, a choke geometry was designed. By employing choke geometry, the leakage can be significantly re-duced. By optimizing the inner shape, all harmful para-sitic modes except from the TM020-mode can be heavily suppressed. This improved TM020-mode RF cavity meets the requirements of the Super Tau Charm Facility (STCF) collider rings.

Speaker: Masahito Hosaka (University of Science and Technology of China)

14:00 Achieving diverse beam modes with modelling and optimisation for the versatile SRF photoelectron gun at SEALab

The SEALab facility in Berlin is home to an R\&D superconducting radio-frequency (SRF)photoinjector setup and beamline. Designed to support multiple varied applications - ranging from Energy Recovery Linac (ERL) to Ultrafast Electron Diffraction (UED) and Electron-Beam Water Treatment (EBWT) - SEALab requires flexible, high-precision tuning to support these diverse beam modes. These applications span over three orders of magnitude in bunch charge, emittance, and current, alongside sub-picosecond pulse lengths. This makes injector setup and tuning a significant challenge. With the world's first beam achieved at SEALab from a Na-K-Sb cathode in our SRF gun, a suite of beam dynamics models has been developed to support understanding of the beam behaviours in the gun, where no observations are possible, and operation of the commissioning process. This is comprised of a first-order analytical model, particle-in-cell (PIC) ASTRA simulations, and a machine-learning surrogate model trained for current commissioning operation ranges. These models are coupled with a Multi-Objective Bayesian Optimisation (MOBO) algorithm to enable rapid tuning across multiple beam modes. This combination of surrogate modelling and optimisation algorithm reduces optimisation timescales from hundreds of hours to minutes, allowing near-real-time tuning for the accelerator. This work presents the modelling framework, its validation, and its application to SEALab's many-mode optimisation challenges.

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

14:00 Advancing heavy ion therapy via particle-in-cell simulations: insights into the interactions between an ion beam with realistic human body-like materials

Heavy ion therapy (HIT) is a transformative approach to cancer treatment offering precision to target tumors minimizing damage to surrounding normal tissue cells. This study explores the feasibility of applying the particle-in-cell (PIC) method to evaluate and optimize the clinical therapy of HIT. The PIC models ion beams & dynamics by tracking their motion with electromagnetic interaction and ion-fluid interactions at the nanoscale. PIC can accurately capture ion energy deposition patterns, ionization processes, and the generation of secondary particles that ion beams traverse in patient-specific body tissues and organs. The results reveal key insights into how ion beams interact with similarly constructed human tissue, influencing dose distribution, and therapeutic outcomes, involving key factors that may affect clinical procedures, such as specific tissue composition, and beam delivery parameters. The outcome would refine HIT protocols, supporting advancements in medical therapy, and enhancing surgical precision. This study also bridges computational modeling with clinical practice, providing actionable insights for improving HIT efficacy and safety.

Speaker: M.C. Lin (Hanyang University)

14:00 Beam dynamics studies and optimization for a compact Cband LINAC for FLASH radiotherapy

Developing medical accelerators for clinical use presents significant challenges, particularly for FLASH radiotherapy, where specific beam parameters are essential to activate the FLASH effect. At Sapienza University, a new electron FLASH LINAC is being developed, designed to deliver FLASH electrons and adaptable for very high-energy electron (VHEE) applications. This work focuses on overcoming the inherent challenges of FLASH radiotherapy: achieving high energy gain in RF structures while transporting high-current electron beams within a compact, cost-effective accelerator. These goals are often at odds, as the high peak currents required for the FLASH effect introduce beam loading, reducing energy gain. Through extensive simulations and optimizations, the accelerator design has been refined, with key improvements in the power supply, RF cavities, and source configuration. This study marks a crucial step toward the realization of compact, scalable, and efficient accelerators for advanced radiotherapy, offering innovative solutions for future medical treatments.

Speaker: Stefano Farina (Sapienza University of Rome)

14:00 Benchmarking Intrabeam Scattering with RF-Track

Intra-beam scattering (IBS) has recently gained significant interest in the community of free electron lasers (FELs), as it is believed to produce an increment in the sliced energy spread (SES), which is detrimental to FEL performance. To control and contain this phenomenon, it is important to include IBS in the design phase of an FEL through appropriate numerical simulation. Most existing codes that simulate IBS were developed for long-term tracking in circular lattices, assuming Gaussian bunches. Unfortunately, this assumption doesn’t capture the rapid bunch evolution of electron bunches in photoinjectors. To address this limitation, the tracking code RF-Track has recently been updated to include IBS, using a novel hybrid-kinetic Monte Carlo method.
This paper presents benchmarks performed to verify the implementation. The predicted SES increment in the beam due to IBS using RF-Track has been compared against a kinetic approach used in a different tracking code and, secondly, against a semi-analytical model. The results showed a good agreement, setting RF-Track as a tool to understand and control the SES growth in photoinjectors and, in particular, in FEL.

Speaker: Paula Desire Valdor (European Organization for Nuclear Research)

14:00 Cavity beam position monitor signal matching by injection pulse

Cavity beam position monitors (CBPMs) are very high-precision devices that, in recent years, have progressed from experimental equipment to standard linac diagnostics in many prominent facilities, most notably free electron lasers. However, the high sensitivity of these devices comes at the cost of a limited measurement range, even with high dynamic range electronics. Furthermore, CBPMs need to be calibrated in situ, ideally by introducing a known beam offset, which is often impractical in large installations. This paper reports on a method to match CBPM beam signals by injecting synchronized and tightly controlled bursts of radio frequency (RF) oscillations into the sensor cavity and reading back their superposition. The method allows compensation for static beam offsets (with beam) and calibrates CBPMs electronically (no beam required), thus removing some of the operational hurdles. We discuss the first demonstration of this method at the Accelerator Test Facility 2 (ATF2).

Speaker: Mark McCallum (John Adams Institute)

14:00 Cavity loops Influence on the single-bunch Instability thresholds of the CERN PS Booster

The CERN Proton Synchrotron Booster (PSB) delivers a wide variety of high-intensity and high-brightness proton beams to several destinations, including operations at the Large Hadron Collider (LHC) and various fixed-target experiments. Following the Long Shutdown 2 (LS2) upgrades, discrepancies between beam measurements and macro-particle simulations were observed, highlighting the need for a deeper understanding of the longitudinal impedance and related effects in the PSB. To address this, longitudinal single-bunch instability studies have been conducted to evaluate the impedance model through the intensity and energy thresholds across different radio-frequency configurations. This contribution presents experimental results that explore instability mechanisms and the effect of the beam loading compensation feedback system. These results are used to benchmark a new cavity loop simulation, which enables more detailed studies of the accelerator impedance.

Speaker: Mariangela Marchi (Sapienza University of Rome)

14:00 Coherent synchrotron radiation instability in steady-state microbunching ring

We study the coherent synchrotron radiation instability in a novel synchrotron light source concept, steady-state microbunching storage ring.

Speaker: Zhuoyuan Liu (Tsinghua University)

14:00 Comprehensive power consumption profiling of KARA for sustainable operations

The negative impacts of global warming and continuously rising energy costs emphasize a need for sustainable and cost-effective operation also for accelerator facilities. This necessitates optimization of accelerator operation, which then requires a comprehensive profiling of accelerator facilities for power consumption patterns to break down the consumption trends of the whole facility. At KIT, as part of the Horizon Europe project Research Facility 2.0, a comprehensive analysis of the Karlsruhe Research Accelerator (KARA) was carried out using the past 1 year of power consumption profiles for all accelerator components. This contribution provides an analysis to identify the overall power consumption profiles of KARA’s main systems, such as the storage ring, cooling plants, and beam-lines. It also explores correlations with factors like weather and temporal variation in consumption patterns on a quarterly, monthly, weekly, and daily basis. The results highlight peak power consumers and consumption periods, as well as the influence of seasonal behavior, accelerator operation modes, and weather patterns.

Speaker: Mahshid Mohammad Zadeh (Karlsruhe Institute of Technology)

14:00 Data fusion based on the symmetric dual-path laser uncertainty weighting method

The construction of fourth-generation accelerators, represented by free-electron lasers and diffraction-limited storage rings, is increasingly popular, which sets higher standards for the installation precision of insertion devices. Large-scale insertion devices are installed using two laser trackers, but a rigorous system has not been established. To enhance installation accuracy, we propose a symmetric uncertainty weighting fusion method. This method integrates the data from two laser trackers with uncertainty weighting through symmetric coordinate transformation, thereby establishing a dual-route laser system. According to actual measurement and simulation results, it has been proven that this method can effectively improve the precision of coordinate system recovery, reduce deviations from theoretical values, and thereby enhance installation precision.

Speaker: Ting Ding (University of Science and Technology of China)

14:00 Data-driven hysteresis compensation in the CERN SPS main magnets

Magnetic hysteresis and eddy current decay continue to challenge beam quality and operational consistency in multi-cycling machines like the Super Proton Synchrotron (SPS) at CERN. Building on our previous work, this paper presents improvements in the data-driven approach for magnetic field modelling to enhance the reproducibility of SPS dipole and quadrupole fields and thus maintain stable beam parameters across all operational cycles. The method is based on feed-forward correction using magnetic field forecasting with machine learning. It now includes additional operational experience and demonstrates that the field error compensation can reliably be used in operation. This contribution proves that hysteresis compensation can be achieved without a feedback system based on expensive installations with online field measurements in reference magnets. The performance improvements achieved by eliminating the need for manual adjustments and reducing time- and energy-consuming accelerator pre-cycles are presented. The paper also sets the stage for future application in higher-order magnets, like sextupoles and octupoles, as well as on other CERN synchrotrons.

Speaker: Anton Lu (European Organization for Nuclear Research)

14:00 Demonstrating a Fisher Information based methodology for optimizing BPM placements in AS2

The next generation Australian Synchrotron project (AS2), is a proposed 4th generation light source, aims to deliver ultra-low emittance $\sim$100 pm-radians and highly coherent, bright light. Constraints on emittance place tight demands on beam optics correction techniques like linear optics of closed orbit (LOCO) and consequently constraints on accurate estimation of the beam centroid along the orbit.

In this work, we propose a Fisher Information Matrix (FIM) -based method for optimizing BPM placement. To achieve this, we use the fully differentiable accelerator code Cheetah, which integrates accelerator modelling with automatic differentiation to enable fast simulations and efficient computation of partial derivatives - including the FIM from the second derivative. Using this we derive optimal BPM placements that minimize variance in estimation of the beam centroid parameters for a segment of the AS2 system.

Speaker: Fareeha Almas (The University of Queensland)

14:00 Demonstrating beam splitting through stable islands formed by the third-order resonance at the CERN Super Proton Synchrotron

In recent years, several new beam manipulation techniques have been proposed that exploit the crossing of nonlinear resonances and the use of stable islands of the transverse phase space. One such manipulation is a novel approach to slow extraction, which combines particle trapping in stable islands with the use of bent crystals to reduce losses on the extraction septum. As a first step towards testing this approach, measurements were performed at the CERN Super Proton Synchrotron (SPS) to demonstrate beam splitting using stable islands of the third-order resonance generated and controlled by sextupole and octupole magnets. The phase-space topology was reconstructed by displacing the beam and observing the turn-by-turn evolution of the signal of the beam position monitors. The beam splitting was achieved by varying both the machine tune and the radial steering of the beam. The measurement results were found to be in excellent agreement with the tracking simulations.

Speaker: Dora Veres (European Organization for Nuclear Research)

14:00 Design and Optimization of a 3 GHz SCDTL for Carbon Ion Acceleration in a Medical Injector

Linear accelerators offer key advantages over circular machines in hadron therapy, such as rapid energy modulation and reduced activation. In this work, we optimized a 3~GHz Side-Coupled Drift Tube Linac (SCDTL) in terms of energy efficiency and the maximum achievable acceleration voltage. Comparative analyses were performed with alternative optimized configurations in TE and TM modes for ions with $\beta = 0.15-0.40$. The optimized structures were subsequently implemented in beam dynamics simulations for the energy upgrade of a carbon ion injector to be installed at the Instituto de Física Corpuscular in Valencia, Spain, achieving full transmission.

Speaker: Eduardo Martínez López (Instituto de Física Corpuscular)

14:00 Design of a novel high-precision beam diagnostic beamline

A novel high-precision beam diagnostic system has been designed for slice emittance and energy spread measurements. The 20-meter diagnostic platform integrates eight quadrupoles, a deflecting cavity, and an energy spectrometer, achieving 100fs temporal resolution in both operational modes through the same beamline layout. The emittance measurement mode provides 50-fold horizontal magnification, while the energy spread measurement mode reaches 1.71 keV theoretical energy resolution through optimized dispersion and screen rotation. Comprehensive error analysis confirms measurement precision of 3.05%±0.69% for relative emittance changes and 4.82±1.35 keV for energy spread variations, demonstrating the effectiveness of this flexible design for high-precision beam diagnostics.

Speaker: Ao Liu (ShanghaiTech University)

14:00 Design of FFA magnet for the laser-hybrid accelerator for radiobiological applications (LhARA)

LhARA, which stands for “Laser-hybrid Accelerator for
Radiobiological Applications”, is a novel and flexible facil-
ity dedicated to research in radiobiology. A proton beam
of energy up to 15 MeV can be produced by a laser driven
source, the beam then enters a Fixed Field Alternating (FFA)
gradient accelerator for acceleration to produce a variable ex-
traction energy between 15-127 MeV. To avoid uncontrolled
beam loss, the operational tune was picked carefully to avoid
resonances. The magnetic field must be adjusted to ensure
that the tune stays at the same working point for different
energy ranges. The FFA ring uses combined-function spiral
magnets, which create a radial magnetic gradient through
distributed conductors wrapped around the pole, each car-
rying a different current. A three-dimensional study was
carried out in OPERA 3D and the parameters of the magnet
were optimized. The results showed that resonances up to
fourth order were avoided for the entire range of acceleration
for different operational energies.

Speaker: Ta-Jen Kuo (Imperial College London)

14:00 Design of high frequency pulse power supply for electron gun

The grid control power supply of the electron gun of the free electron laser (FEL) is a high frequency pulse power supply (HF-PPS), which has a special time structure. The macro pulse repetition frequency of the HF-PPS designed in this paper is 10 Hz, and the micro pulse repetition frequency is 476 MHz.

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

14:00 Design study of HTS air-cored cyclotron coil system for medical RI production

The high current density of HTS material allows electromagnet to induce sufficiently strong magnetic field without relying on any iron core. This permits the design of air-cored cyclotron, where the absence of iron core brings the properties of light-weight and high field reproducibility, making it an ideal medical cyclotron to be installed inside hospitals. However, the cyclotron coil system need to induce highly accurate field while satisfying the engineering restriction from the HTS coil. Compact size, small fringe field and minimum fabrication cost are also desirable at the same time.
A HTS coil system of air-cored cyclotron is designed with the above restrictions taken into consideration. Multiple beam type accelerations that are required for medical RI production are simulated, in order to verify the usefulness of this design. In this work, the coil system design, the magnetic field and the HTS coil properties are presented. The feasibility of actual fabrication and in-hospital installation is discussed.

Speaker: Tsun Him Chong (Osaka University)

14:00 Design, fabrication, and characterization of 3D-printed photonic crystals for THz filtering applications in particle accelerator

The advancement of broadband terahertz (THz) sources has become increasingly important for various scientific and technological applications, including those in particle accelerators. To enable tunable and flexible THz source development, components capable of selective THz spectrum filtering are essential. In this work, we investigate the use of 3D-printed photonic crystal structures, specifically woodpile designs, for THz filtering applications. Using high-precision digital light processing (DLP) 3D printing, we successfully fabricate woodpile photonic crystals with high accuracy. The fabricated structures demonstrate effective spectral filtering capabilities within the THz range, offering promising potential for applications in advanced accelerator technology and related fields.

Speaker: Juna Wernsmann (Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL))

14:00 Development and testing of an autocorrelator for measuring the duration of picosecond pulses of near infrared radiation

The paper presents a design of an autocorrelator manufactured to measure the duration of infrared picosecond pulses of radiation from the 3rd laser of the Novosibirsk Free Electron Laser facility, as well as the results of testing the autocorrelator when measuring the duration of picosecond pulses in the visible range. The results and future plans for future experiments using developed autocorrelator

Speaker: Vladislav Borin (Russian Academy of Sciences)

14:00 Development of a beam profile monitor based on the YAG:Ce scintillator for a multipurpose beam diagnostic system

In this paper, a multipurpose beam diagnostic system based on a YAG:Ce scintillator is presented. This system was developed in order to measure beam profile, transverse parameters, momentum spectrum, and current of the electrostatic accelerator. The concerning issues in the beam profile monitor design such as image resolution and scintillator temperature distribution have been discussed. In order to estimate the resolution of the scintillator screen, the collision of ideal proton and electron beam with YAG:Ce scintillating screen was simulated using the Geant4 Monte Carlo code. Increasing scintillation temperature will decrease the scintillation optical yield and result in a change in beam profile, so COMSOL software was used to simulate the scintillation temperature distribution under different beam powers. The design procedure, including the handling of heat transfer and charging accumulation issues, as well as estimation and improvement of image resolution, has been investigated. After designing the beam profile monitor based on YAG:Ce,The equipment was provided and manufactured and the beam profile was measured using this diagnostic tool.

Speaker: Ali Najafiyan (Shahid Beheshti University)

14:00 Development of a DAQ system for a High Resolution cavity BPM for the future linear collider

A cavity beam position monitor (cBPM) developed by
CEA Saclay was installed at the end of the Accelerator Test
Facility (ATF) linac to evaluate the combined performance
of the monitor and its associated signal processing system.
The setup incorporates a down-conversion architecture inspired
by Royal Holloway, University of London (RHUL),
and employs a digital down-conversion (DDC) algorithm
to extract beam position. This configuration enables highsensitivity
measurements of the transverse beam position.
Preliminary results confirm successful signal acquisition
and a clear position-dependent response, validating the integrated
performance of the cBPM, analogue electronics,
and digital processing chain. The results underscore the
necessity of reliable local oscillator (LO) phase-locking to
ensure precise position determination.

Speaker: Laura Pedraza (Instituto de Física Corpuscular)

14:00 Development of a friendly high-energy irradiation environment for future space developments

Effect assessments of high-energy radiations on materials and equipment are expected to become increasingly important in near future space developments. We initiated a project to construct an irradiation environment with high-energy radiations using the electron linear accelerator at Nihon University. The advantages of using this accelerator include the accelerations up to 100 MeV for high-energy and high-dose irradiations, its easy accessible location from Tokyo area. These advantages help many users including venture companies to use the irradiations with much less difficulties, that we consider as an important key to enhance future space developments.
The electron linear accelerator sends electron beams with a wide energy range to the FEL line by bending them 90 degrees with two 45-degree bending magnets. Irradiation tests are planned to be conducted using the radiation produced in this process. In this study, we present a simulation result on the acceleration process of the electron beam and the amount of radiation generated by the 45-degree bending magnets. We also show dosimeter measurements by the high-energy irradiations to be compared with the simulation results.

Speaker: Mizuki Kurata (Nihon University)

14:00 Development of a new type adjustable strength permanent magnet quadrupole

An integrated concept is presented to design a permanent quadrupole magnet (PQM) using tunning modules simultaneously for varying magnetic field gradient. It is anticipated that this design will be utilized for Hefei Advanced Light Facility (HALF) in the future. This design leverages symmetry to achieve both a broad range of magnetic field gradient tunning and a narrow range of precise magnetic field gradient tunning, and produce desired high-quality quadrupole magnetic fields. The PQM primarily achieve magnetic field gradient tunning by modifying the size and position of the tunning modules. The tunning of a wide spectrum of magnetic field gradient is mainly achieved by altering the excitation direction of permanent quadrupole magnets within the tunning module. The precise manipulation of small-scale magnetic field gradient is mainly achieved by manipulating the tunning-tube to modify the excitation effect exerted by the tunning module on the central magnetic field. In light of the aforementioned principles, we propose a design for a quadrupole magnet with a magnetic field gradient approximating 70T/m and magnetic gradient tunning range attain 40% in an aperture radius of 14mm.

Speaker: Shaoxiang Dong (University of Science and Technology of China)

14:00 Direct interpretation of coherent synchrotron radiation modeling from the Lienard-Wiechert equation with shielding

Coherent Synchrotron Radiation (CSR) plays a critical role in beam dynamics, significantly influencing beam shape and energy characteristics in particle accelerators. This study investigates the CSR effect through a comprehensive numerical approach, starting from the fundamental Lienard-Wiechert equation and utilizing an explicit, non-approximated methodology to explore beam energy dynamics. This paper focuses on simulating CSR effects in conjunction with the shielding effect from parallel plates, which are crucial in mitigating potential beam energy loss. By benchmarking results against Saldin's established work *, the study examines wakefield characteristics, particularly the high-peak behavior at small particle separations.

Speaker: Chia-Heng Huang (National Central Univeristy)

14:00 Disentangling sudden beam loss events and fast beam abort system with the RFSoC-BPM at SuperKEKB

In the SuperKEKB/Belle-II experiment, various new physics searches are conducted by colliding 4 GeV positrons and 7 GeV electrons. Future plans aim to significantly increase luminosity, targeting an integrated luminosity 100 times higher than current levels. However, the realization of this goal is challenged by the phenomenon of "Sudden Beam Loss" (SBL), characterized by the abrupt disappearance of the beam within tens of microseconds. As presented at IPAC'24, we developed the RFSoC-BOR (Bunch Oscillation Recorder) system, based on the AMD/Xilinx RF System on Chip (RFSoC). This system enables bunch-by-bunch beam position monitoring and detailed SBL data acquisition. Using the RFSoC-BOR, we analyzed SBL events, identified key contributing factors, and gained insight into strategies for mitigation. Our findings have advanced the understanding of SBL, bringing SuperKEKB closer to higher luminosity operation. Additionally, we are extending the functionality of the RFSoC-BOR to develop a fast beam abort system that improves accelerator component protection. This presentation will cover the role of the RFSoC-BOR in SBL analysis, key insights, and progress on the fast beam abort system.

Speaker: Riku Nomaru (The University of Tokyo)

14:00 Effects of chromaticity and space charge on coupled bunch instability in CSNS/RCS

Coupled bunch instability was observed during beam commissioning of CSNS/RCS. The instability was successfully suppressed by installing sextupoles to control chromaticity. The instability exhibits characteristics influenced by the strength of space charge. We conducted a theoretical study on the effects of chromaticity and space charge on coupled bunch instability and compared results with simulation and measurements. This work provides valuable insights for beam control in the second phase of CSNS.

Speaker: Li Rao (Institute of High Energy Physics)

14:00 Engineering magnetic carbon nanotubes via swift heavy ion irradiation for spintronics and quantum technologies: XAS and RAMAN study

Carbon nanotubes (CNTs), known for their versatility as 2D materials, are key to advancing quantum technologies such as qubit fabrication and magnetic data storage. In this study, multi-walled carbon nanotubes (MWCNTs) doped with magnetic impurities (Fe and Co) were exposed to swift heavy ion (SHI) irradiation to explore induced structural modifications. SHI beams transfer energy to the carbon matrix via electronic energy loss and thermal spikes, causing Fe and Co ions to agglomerate within interstitial regions and defect sites of the CNT matrix. Structural changes were analyzed using high-resolution X-ray diffraction (HRXRD), Raman spectroscopy, and near-edge X-ray absorption fine structure (NEXAFS). HRXRD revealed peak dissolution, reduced crystallinity, and increased lattice strain, while Raman spectra showed partial annealing of damaged CNTs with disorder parameter reduction (FeCNT: 0.65→0.57; CoCNT: 0.55→0.52). NEXAFS confirmed non-destructive processing. These findings link ion fluence with defect engineering, paving the way for magnetic CNTs in spintronics and data storage.

Speaker: Priyal Singhal (Panjab University)

14:00 Equivalent circuit analysis of waveguide filter

Shanghai Synchrotron Radiation Facility/Shanghai Soft X-ray FEL Facility has developed an advanced transverse deflecting structure TTDS (two-mode transverse deflecting structure), using two different rf power sources to deflect beam in any angle. Bandpass filter is a key component in the TTDS, designed to pass low-frequency signals while blocking high-frequency ones. This study uses an equivalent circuit approach to analyze the RF performance of the bandpass filter. By calculating the required S-parameters, an equivalent circuit model is derived to guide the structure and dimension design. The equivalent circuit analysis not only provides valuable insights for the design and optimization of the bandpass filter in TTDS but also offers a useful reference for the design of other waveguide filters in accelerators.

Speaker: Hanyu Gong (Shanghai Institute of Applied Physics)

14:00 Evaluation of an X-band LLRF prototype for the EuPRAXIA@SPARC_LAB LINAC

EuPRAXIA, the "European Plasma Research Accelerator with eXcellence In Applications," represents the next generation of free-electron lasers (FEL). It aims to develop a compact, cost-efficient particle accelerator using innovative wake-field accelerator technology. High-energy physics often demands higher acceleration voltages, and X-band technology offers high gradients in compact structures. The EuPRAXIA@SPARC_LAB LINAC injector, featuring an S-band RF gun, four S-band structures, and sixteen X-band structures, achieves a maximum beam energy of 1 GeV. For femtosecond-level synchronization and stability, Low-Level Radio Frequency (LLRF) systems are essential. However, commercial X-band LLRF solutions for 100 ns pulse processing are unavailable. This project, in context of the EuPRAXIA - Doctoral Network, develops an X-band LLRF prototype tailored to meet the EuPRAXIA@SPARC_LAB LINAC's stringent requirements. After validation on a testbench, the prototype will enable industrial production and commercialization. This paper presents the Front-End, Back-End analysis, and further evaluation of the prototype.

Speaker: Phani Deep Meruga (Instrumentation Technologies (Slovenia))

14:00 Experimental investigation of longitudinal scraping of H- bunches via photo-detachment

Longitudinal emittance growth is a significant challenge in RF linacs, especially for poorly bunched beams. This stems from particles occupying outer synchrotron oscillation orbits in the LBET, causing unwanted bunch-bunch interactions and degraded beam quality. To address this, we proposed using temporally spaced laser pulses to selectively photo-detach electrons from the longitudinal head and tail regions of H- ion bunches. This approach aims to reduce particle density in extreme orbits, enhancing beam uniformity and limiting emittance growth. Our experiments employed Fermilab's 'LaserNotcher' system at the font end of the linac, delivering 1.6 MW peak power with sub-nanosecond precision. By neutralizing the first and last half-nanosecond of several H- bunches, we measured their propagation injection into the booster. Measurements of pulse width, average height, and temporal spacing over booster cycles were compared between the scraped and unscraped bunches. Statistical analysis evaluated the results’ significance, highlighting the feasibility of laser-based scraping for future linac designs to achieve higher beam energies with improved emittance control.

Speaker: Parker Landon (Boston University)

14:00 Extended phase space tomography for EOSD simulation considering crystal geometry effects

This theoretical study presents an advanced method for longitudinal phase space tomography in electron storage rings, focusing on reconstructing phase space densities from electro-optical spectral decoding (EOSD) measurements that incorporate crystal geometry effects. The EOSD crystal geometry significantly impacts the measurement signal due to signal integration along its length and interference from wake fields and Cherenkov diffraction radiation (ChDR). These effects add challenges to reconstructing the original phase space density from experimental data.
To address these challenges, we integrate two theoretical frameworks. First, we employ the Vlasov-Fokker-Planck equation to model the turn-by-turn evolution of the charge density distribution. Second, CST simulations of the bunch profile characterize the electric field inside the crystal, enabling a tailored simulation for the EOSD system at the Karlsruhe Research Accelerator (KARA). By combining these approaches, we propose a refined tomography method that more accurately reconstructs the longitudinal phase space from sensor data, effectively capturing the interplay between bunch dynamics and the EOSD system configuration.

Speaker: Felipe Donoso (Karlsruhe Institute of Technology)

14:00 Extracting symplectic maps for space-charge dominated beams

Symplecticity of the transfer maps is important for reliable evaluation of space-charge dominated beams in accelerators. Unfortunately, most simulation codes that include collective effects, such as space charge, do not use canonical phase-space variables and therefore are not symplectic in the presence of electromagnetic fields. In this paper, we present a numerical method to extract symplectic transfer maps using particle tracking simulation code IMPACT-T for space-charge dominated beams. We demonstrate this method by obtaining symplectic transfer maps in the photo-injector (113 MHz SRF gun) section of the Coherent electron Cooling (CeC) Proof of Principle (POP) experiment.

Speaker: Nikhil Bachhawat (Stony Brook University)

14:00 Fast cyclotron beam probe at UC Davis Crocker Nuclear Laboratory

The UC Davis Crocker Nuclear Laboratory houses a 72-inch multi-species Isochronous Cyclotron built in the 1960’s. For many years, previously unexplained beam dynamics have been indirectly observed at the cyclotron by both internal and external experimenters. Investigating these effects within the cyclotron, at the bunch level, has proven particularly challenging due to the cyclotron's harsh environment of strong magnetic fields, high radiation levels, intense RF interference, and limited space. To address these challenges, a compact segmented beam probe was developed, utilizing a scintillator array target coupled to a SiPM array positioned outside the cyclotron via fiber optic cables. This novel beam probe has enabled precise, high-speed measurements of individual beam bunches, providing data to theoretical models and deepening the understanding of beam dynamics allowing for more precise operation of the cyclotron. These advancements are driving efforts to optimize cyclotron performance for diverse applications, including isotope production, ocular melanoma therapy, and a variety of experimental research.

Speaker: Logan Knudson (Crocker Nuclear Lab)

14:00 First magnetic field penetration results of multilayer samples and A15 materials for the use in SRF applications

Superconducting radiofrequency cavities made of bulk Nb are reaching their theoretical limits in the maximum accelerating gradient, Eacc, where Eacc is limited by the maximum magnetic field, B, that can be applied on the surface of the accelerating cavity wall. To increase Eacc, the maximum B field, Bmax, which can be applied to the surface, must also be increased. The A15 materials or multilayer structures are the potential solution to increase Bmax., Since coating and RF testing of full size RF cavities is both expensive and time consuming, one need to evaluate new ideas in superconducting thin films quickly and at low cost. A magnetic field penetration experiment has been designed and built at STFC Daresbury Laboratory to test superconducting samples (< 100 mm ). The facility produces a parallel DC magnetic field, which applied from one side of the sample to the other similar to that in an RF cavity. The facility applies an increasing magnetic field at a set temperature to determine the field of full flux penetration which can give an insight into the quality and structure of the superconducting structure.

Speaker: Liam Smith (Science and Technology Facilities Council)

14:00 First proton crabbing at the LHC via head-on beam-beam interaction

The first experimental observation of a 10 $\mu$m crabbing orbit at 1~$\sigma_z$ induced by head-on collisions with a non-zero crossing angle ($\theta_c$) in a high-energy proton beam at the LHC is presented. This challenging measurement required both the design of a dedicated experiment and a careful calibration and optimization of the beam instrumentation to produce and detect such a subtle effect. By varying the crossing angle from positive to negative values the reversibility of the effect and its dependence on the crossing angle were also demonstrated. Lattice simulations were performed to corroborate the experimental results, showing excellent agreement with the measured crabbing amplitudes. This experiment highlights the potential of the existing wideband beam-position monitors to diagnose crabbing effects, which will be crucial in the HL-LHC upgrade.

Speaker: Andrea Fornara (University of Manchester)

14:00 Formulas of coherent synchrotron radiation induced microbunching instability in an arbitrary dogleg lattice

The microbunching instability (MBI) has long been a persistent issue in high-brightness electron beam transport. The dogleg structure, a dispersive configuration composed of two quadrupole magnets and dipole magnets, has drawn attention in recent studies. It has been pointed out that the Landau damping effect can be enhanced to effectively suppress the microbunching instability by adjusting the strength of two quadrupole magnets preceding the dogleg structure. In this work, we derive an analytical formula for the CSR-induced microbunching gain in a dogleg lattice based on the iterative approach. The formulas have been benchmarked against semi-analytical Vlasov calculations. The analytical formulas obtained in this paper can be used to explore the influence of the strength of the quadrupole magnets in front of the dogleg lattice on the final microbunching instability, and also to verify the effectiveness of suppressing MBI in the dispersive region where the dogleg is located.

Speaker: Bingxi Liu (Huazhong University of Science and Technology)

14:00 Functional design of a wideband RF system for HeLICS synchrotron

Within the framework of the NIMMS (Next Ion Medical Machine Study) initiative at CERN, a comprehensive design study is being performed for the Helium Light Ion Compact Synchrotron (HeLICS), a compact accelerator for hadron therapy. A key component of this facility is the radiofrequency (RF) cavity. Its proposed design is based on the wideband technology successfully implemented in the CERN PS Booster. It comprises four cells filled with FINEMET material that enable the acceleration of protons and $^4He^{2+}$ over a broad energy range. The cavity, designed to deliver a peak voltage of up to 2 kV within a frequency range up to 10 MHz, features a compact design to meet the stringent requirements of a compact medical accelerator. It operates in double-harmonic mode, to effectively reduce longitudinal line density and mitigate space-charge effects at low energy. The combination of compactness and operational flexibility positions this RF cavity as an optimal solution for compact synchrotrons, enabling more efficient, precise, and accessible hadron therapy for cancer treatment.

Speaker: Vincenzo Sansipersico (Riga Technical University)

14:00 High Luminosity LHC optics: machine development results

As the High Luminosity LHC (HL-LHC) era approaches, precise control of the accelerator becomes increasingly critical. Machine studies are essential to address the forthcoming challenges and develop correction strategies based on experimental measurements. Although the upgraded inner triplets are not yet available, key features of the HL-LHC optics can still be investigated. This includes exploring the high Achromatic Telescopic Squeeze (ATS) factors in the neighboring arcs of the high-luminosity interaction regions, particularly under flat optics configurations. A beta blow-up is also implemented in the long straight section containing most of the beam instrumentation to improve their sensitivity at top energy. This paper presents experimental measurements, evaluates arc phase errors, and discusses the implementation of local corrections. Sextupole bumps in the arcs were employed to mitigate these errors, demonstrating their effectiveness in optimizing machine performance.

Speaker: Yannis Angelis (Aristotle University of Thessaloniki, European Organization for Nuclear Research)

14:00 Identifying 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. 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 Impact of collimators’ geometric impedance on beam stability in FCC-ee

Beam stability in the FCC-ee collider is strongly influenced by transverse and longitudinal beam coupling impedance. Developing a flexible and comprehensive impedance model is crucial for accurately evaluating and mitigating instabilities as machine parameters evolve. This study investigates the effect of the FCC-ee collimation system, identifying it as a dominant source of total machine impedance. Both resistive and geometric contributions are analyzed, with geometric effects found to play a critical role in shaping the overall impedance landscape. Accurately modeling collimators’ geometric impedance is essential for beam stability assessment. Such modeling enables global impedance considerations, accounting for the interplay between different accelerator elements and guiding the definition of critical design parameters.

Speaker: Dora Gibellieri (European Organization for Nuclear Research)

14:00 Introducing an open-source 3d electromagnetic wakefield solver for beam-coupling impedance simulations

The determination of electromagnetic wakefields and their impact on accelerator performance is a longstanding challenge in accelerator physics. These wakefields, induced by the interaction between a charged particle beam and the surrounding vacuum chamber structures, significantly affect beam stability and power dissipation. Accurate characterization of these effects via beam-coupling impedance is crucial for predicting and mitigating performance limitations. While analytical methods are sufficient for simple geometries, realistic accelerator components require full-wave, three-dimensional numerical solutions of Maxwell's equations. In alignment with CERN's Open Science initiative, this contribution introduces an open-source 3D electromagnetic time-domain solver specifically designed for computing wake potentials and impedances in arbitrary geometries. The solver’s numerical implementation, optimized for CUDA-enabled GPUs, is presented and validated through benchmarks against established commercial codes. By fostering a collaborative framework, this solver aspires to address emerging challenges in accelerator design.

Speaker: Elena de la Fuente (European Organization for Nuclear Research)

14:00 Investigating beam-induced electron emission from thin wires in PSI proton beams

The emission of electrons induced by beam interaction with thin targets is a phenomenon used to measure various properties of particle beams. The main processes of electron emission are: secondary emission, delta electron production and thermionic emission. The last one is not desired, because the intensity of thermionic electrons is not directly related to beam density profile. A common technique to suppress thermionic emission employs bias potential on the wire, which allows for recapturing of low energy electrons. This study investigates the effectiveness of the bias voltage method for high-brightness proton beams of the HIPA accelerator. Through experiments and simulations, the study aims to better understand the emission spectra, the suppression of thermionic emission, and the effects of beam fields on electron dynamics.

Speaker: Dr Mariusz Sapinski (Paul Scherrer Institute)

14:00 Investigating the Impact of alternative LHC optics on accelerator backgrounds at FASER using BDSIM

Alternative configurations around the ATLAS experiment are investigated aiming to reduce muon rates at forward physics experiments such as FASER and SND@LHC. The Geant4 toolkit BDSIM is used to propagate muons through a model of a section of the LHC and the TI12 tunnel, where the FASER experiment is located. We compare the muon rates in BDSIM with FASER data collected during dedicated tests in the LHC. Results show a significant worsening of the background with the non-nominal polarity configuration of the triplet quadrupoles, used in 2024. The horizontal crossing angle further increased the background, however a partial mitigation of approximately 10% was found using a set of orbit corrector magnets. Additionally, nominal triplet polarity was favorable for both vertical and horizontal crossing angles. This work served as benchmark of simulations that will be used to validate future configurations.

Speaker: Alex Keyken (Royal Holloway University of London)

14:00 Laser wakefield accelerator-driven photonuclear reactions for the production of medical radionuclide 67Cu

Recent results of production of the medical radionuclides 67Cu using a laser wakefield accelerator (LWFA) are presented. This emerging technique utilises powerful, ultrashort laser pulses that are focussed into a gas jet to create a plasma wake that traps and accelerates electrons to very high energies with large accelerating gradients. Accelerated electrons interact with high-Z material to produce high-energy photons by bremsstrahlung, which then produce 67Cu via the 68Zn(γ, p)67Cu photonuclear reaction.
67Cu, with 62 h half-life, is considered ideal radioisotope for treatment of lymphoma and colon cancer.* The production of 67Cu requires medium-energy (~70 MeV) protons that are only available at limited number of facilities.
We present the experimental setup, maximising electron pulse intensity by optimising laser beam properties and target composition of gas jet. The gamma beam and the design of 68Zn are optimised using FLUKA simulations. We will also report on the development of detectors for online monitoring of the electron and gamma beams, and produced activities of the radionuclides.

Speaker: Baris Bingol (University of Strathclyde)

14:00 Longitudinal beam size measurement at the Novosibirsk FEL

The Novosibirsk Free Electron Laser (NovoFEL) is a facility that consists of three free electron laser (FEL) systems installed on different parts of the Energy Recovery Linac (ERL). These three FELs share the same acceleration system, which enables the generation of high average electron current, typically around 10 mA. Precise measurement of the electron beam parameters is essential for monitoring the performance of the accelerator and tuning its operating modes. One of the most important parameters is the length of the electron bunch, as it directly affects the efficiency of the laser radiation generation process. This paper presents the results of experiments conducted to study the behavior of the longitudinal beam size in various Novosibirsk FEL lasers. For these experiments, we used Cherenkov radiation produced by a beam of electrons passing through a thin aerogel plate. The resulting flash of radiation was captured by a streak camera, allowing us to determine the longitudinal size of the electron beam. The results of the study on the dependence of the longitudinal beam size on various accelerator parameters are presented.

Speaker: Stanislav Reva (Budker Institute of Nuclear Physics SB RAS & Novosibirsk State University)

14:00 Machine learning for the anomaly detection and characterization of the 24 GeV/c proton beam at CERN IRRAD Facility

The accurate assessment of beam quality is the most important aspect in the irradiation facilities operation such as IRRAD at CERN. The Beam Profile Monitor (BPM) sensor system developed for the high-intensity proton beam at IRRAD features minimal particle interaction, improved radiation hardness and higher sensitivity and sampling rate than previous systems. It provides a wealth of high-quality BPM data not available earlier, enabling the development of data processing more advanced than before. To take advantage already today of this upgraded BPM system’s features, we propose innovative Machine Learning (ML) techniques to adapt and improve upon existing DAQ technology.
This paper details the application study of (1) autoencoder architectures to perform the automatic pattern recognition and anomaly detection of proton beam profiles, and (2) deep learning techniques to predict relevant beam parameters. We applied this approach to a new dataset (made publicly available) of BPM data taken during the recent runs of IRRAD; our preliminary results demonstrate good performance in comparison to existing methods. This work is a first step towards the "intelligent" irradiation facilities.

Speaker: Jaroslaw Szumega (European Organization for Nuclear Research)

14:00 Magnetic field control in the MedAustron synchrotron

MedAustron, a synchrotron-based ion therapy centre in Austria, is focused on enhancing cancer treatment performance. A key improvement opportunity lies in the regulation of the main ring bending dipoles, which currently require time-consuming procedures to ensure reproducibility and reliability of the associated magnetic fields (B-Fields). Other therapy centres globally address this through a traditional B-train or similar systems to regulate on the B-Field and mitigate parasitic effects. In contrast to that, we propose a novel approach utilising a single Hall probe measurement inside a reference magnet, fused with a magnet model to provide real-time, high accuracy estimates of the integral B-Field for regulation. This technique, combined with a tailored controller, is evaluated under typical therapy cycling conditions. The system's performance is demonstrated through metrological analysis and beam property comparisons. Most importantly, the results show the possibility of significant improvements in treatment time reduction. Ultimately, the already achievable beam position accuracy, and spill structure in the treatment rooms, enable the start of commissioning in 2025.

Speaker: Thomas Margreiter (EBG MedAustron GmbH)

14:00 Measurement of magnetic field characteristics using the stretched wire system

In order to explore an efficient and accurate method for measuring the magnetic field information of accelerator magnets, this paper used the stretched wire system to measure a quadrupole magnet prototype of Hefei Advanced Light Source. In the measurement process, the integral field of the magnet at multiple points was first measured to calculate the magnetic center and multipole components of the magnet, and the influence of various measurement methods on the multipole components of the magnet was explored. Furthermore, the method of measuring magnet deflection angle using the stretched wire system and the method of correcting multipole components through magnet deflection angle were explored. The measurement results indicate that the stretched wire system has sufficient functionality and accuracy to measure the magnetic field information of the magnet.

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

14:00 Measurement of slice energy spread of a high brightness electron beam using a passive dielectric-lined waveguide structure

In this study, we investigated the possibility of using a passive dielectric-lined waveguide structure on slice energy spread measurement of femtosecond electron beam. Such diagnostic setup for a 25 MeV electron beam with a duration of a few hundred femtoseconds is simulated using IMPACT-T. The DLW acts as a passive streaker by generating traverse wakefields that deflect the electron bunch. Simultaneously, a dipole magnet serves as a spectrometer, separating the slice energy distribution, which is then visualized on YAG screen. The DLW’s wakefields significantly broaden the transverse beam profile on the screen, with the beam tail experiencing a stronger transverse kick than the head. This effect results in a beam separation on the vertical axis. To analyze the wakefields, CST simulations are used to compute wake potential excited by a Guassian beam. By proper deconvolution, the corresponding transverse wake function is obtained. This wake function is combined with IMPACT-T simulations and a 6D phase space distribution to deduce the slice energy spread. The results demonstrate a promising approach for diagnostics that helps to optimize free-electron laser (FEL) drive beams.

Speaker: Chihkai Liu (National Central Univeristy)

14:00 Measurement of the radiation damping time via optical methods

The radiation damping time is a crucial parameter that depends on the overall magnetic structure of the accelerator. Accurate measurement of this damping time can provide insights into the fidelity of the accelerator model by allowing for a comparison with calculated damping time values. In this study, we present a series of measurements of radiation damping times at the VEPP-4M and VEPP-2000 collider at BINP. In order to determine the damping time, we recorded the transverse beam profile using a digital camera. The results includes study of the damping times at revolution frequencies and different energies of the beams.

Speaker: Veronika Maior (Budker Institute of Nuclear Physics SB RAS & Novosibirsk State University)

14:00 Measurement of vertical and horizontal emittance via undulator high harmonics at the APS-U

The transition from 3rd to 4th generation synchrotron light sources can primarily be characterized by a significant reduction in horizontal emittance. This enables a nearly uniform transverse X-ray beam profile and a brilliance that approaches the diffraction limit. A consequence of the upgrade to Diffraction Limited Storage Rings (DLSRs) is that the traditional emittance measurement techniques lack the resolution required to accurately measure emittances in the picometer-radian range. At the Advanced Photon Source Upgrade (APS-U), we explore the use of high harmonics of undulator radiation for precise emittance characterization. Previously at the Advanced Photon Source (APS), vertical emittance measurements, validated through SPECTRA simulations, were performed. This drove the desire to measure the horizontal emittance at the APS-U. Simulations performed in SPECTRA and Synchrotron Radiation Workshop (SRW) guide our experimental strategy for characterization. We present measurements of both the horizontal and vertical emittance at the APS-U, including variations across different bunch timing modes. We conclude by discussing the advantages of this approach over traditional methods.

Speaker: Emmanuel Aneke (Northwestern University)

14:00 Measurement techniques using the electron beam profile scanner at the Fermilab Main Injector

This work presents techniques for non-invasive transverse profile measurements of high-intensity proton beams using an Electron Beam Profile Scanner (EBPS). The EBPS utilizes low-energy electrons as a probe to analyze the transverse size of proton beams, allowing for potential analysis on a single-bunch basis. Recent upgrades to the Fermilab Main Injector have enhanced beam power on target to 1 MW, with future developments targeting 2 MW. The higher beam power has increased the demand for non-invasive diagnostics, as invasive methods can disrupt operations.
The techniques presented include 1) the slow scan technique, which serves as a proof of concept for the probe beam, 2) the one-shot scan technique for measuring horizontal beam profiles, and 3) the raster scan technique for analyzing horizontal beam profiles as a function of the longitudinal distribution of the beam. The profiles obtained will be crucial for studying and understanding instabilities in high-power, high-intensity proton beams. This will contribute to optimizing the operation of high-power proton accelerators by minimizing beam loss, activation, and damage to both the diagnostics and the accelerator components.

Speaker: Matilda Mwaniki (Illinois Institute of Technology)

14:00 MENT algorithm for transverse phase space reconstruction at SIRIUS

The injector system of SIRIUS, the brazilian 4th generation synchrotron light source, currently operates with non-ideal injection efficiencies, which may impose limits to future top-up operation modes. Within this context, diagnostic techniques to access beam quality in the injector are essential tools for optimizations. In this work, the MENT algorithm was implemented for the reconstruction of two-dimensional probability densities, aiming to determine the electron density in the transverse phase space at the end of the LINAC. The implemented method has been validated through simulations of several distributions, demonstrating its reliability, and applied to analyze preliminary experimental results.

Speaker: Otávio Silveira (Brazilian Synchrotron Light Laboratory)

14:00 Metamaterial absorbers for beam-coupling impedance mitigation

Charged particle bunches traversing cavity-like discontinuities in the beam pipe at relativistic velocities excite electromagnetic resonant modes that can detrimentally affect the dynamics of trailing bunches. This beam-cavity interaction, characterized in the frequency domain through the concept of beam-coupling impedance, poses significant challenges for beam stability and performance in high-energy particle accelerators. While conventional mitigation strategies encompass higher-order mode (HOM) couplers and lossy ferrite insertions, novel approaches leveraging metamaterial properties offer promising alternatives for selective mode damping. This investigation explores advanced metamaterial-based structures designed to specifically target and attenuate higher-order modes, thereby selectively reducing the beam-coupling impedance resonances.

Speaker: Leonardo Sito (University of Naples Federico II)

14:00 MTE measurements at the ASU cryogenically cooled DC electron gun

The ASU cryogenically cooled DC electron gun represents a state-of-the-art platform for testing novel photocathodes at room and cryogenic temperatures. The key electron beam diagnostic tool of this setup is the four-dimensional (4D) phase space reconstruction using the pinhole scan technique. In this work, we use the 4D phase space measurement to extract the Mean Transverse Energy (MTE) obtained from cathodes in this gun. We also establish the limits and accuracy of the 4D phase space and emission area measurements and estimate their effects on the MTE extracted. The results, validated through simulations and complementary measurements establish the use of the 4D phase space measurement technique to obtain the MTE. Using this approach, we measure the MTE from alkali antimonide photocathodes at varying temperature and electric field conditions. This study provides a robust foundation for future experiments with the ASU electron gun and beamline, paving the way for advanced photocathode characterization under cryogenic conditions.

Speaker: Peter Owusu (Arizona State University)

14:00 Multi-objective optimization of ring cyclotron RF cavity using neural network ensembles with uncertainty quantification

This study presents a multi-objective optimization scheme for ring cyclotron RF cavities, leveraging a neural network ensemble surrogate model. The cavity geometry is parameterized using Non-Uniform Rational B-Splines (NURBS), with control points and weights as design parameters. To reduce the computational cost of direct eigenmode simulations, an ensemble of neural networks trained using Ansys HFSS results is used to approximate performance metrics efficiently. The surrogate model also quantifies uncertainty, enabling Monte Carlo error propagation to account for potential manufacturing deviations. A multi-objective genetic algorithm (MOGA) explores the design space, using the surrogate model for efficient evaluations. The neural network ensemble are periodically retrained through HFSS simulations, iteratively improving the accuracy of surrogate model. This approach gives a robust and reliable RF cavity design optimization scheme.

Speaker: Ahsani Hafizhu Shali (Osaka University)

14:00 New analysis tools for LHC aperture measurements

Aperture measurements at the Large Hadron Collider (LHC) are routine procedures conducted during the early stages of beam commissioning, prior to the injection of high-intensity beams. This is to ensure that the aperture, defining the clearance for the circulating beams, is protected by the LHC collimation system. Local aperture measurements are performed to probe the available aperture at specific locations. Such measurements are carried out by applying a local orbit bump in the area of interest. The bump amplitude is increased until the beam touches the aperture, visible through signals in the local Beam Loss Monitors. This contribution introduces a refined approach to analyse local aperture measurements by incorporating measured beam position monitor (BPM) signals to enhance the precision of the analysis. Using the Xsuite package, the orbit bump is simulated and rematched to the measured BPM signal to enhance the analysis and quantify the uncertainties with respect to the theoretical beam orbit. Using past measurement data, we compare the results obtained using the established and revised methodologies and conclude on derived measurement uncertainties.

14:00 Nonstationary dynamics of vortex electron beam in magnetic lens

The Landau states of electrons with orbital angular momentum in magnetic fields are important in the quantum theories of synchrotron radiation at storage rings and in many other areas. In realistic scenarios, electrons are often born inside the field or injected from a field-free region, requiring nonstationary quantum states to account for boundary or initial conditions. This study presents nonstationary Laguerre–Gaussian (NSLG) states in a longitudinal magnetic field, characterizing vortex electrons after their transfer from vacuum to the field. Comparisons with Landau states show that the r.m.s. radius of the electron packet in the NSLG state oscillates in time around a significantly larger value than that of the Landau state. This quantum effect of oscillations is due to boundary conditions and can potentially be observed in various problems, particularly when using magnetic lenses of linear accelerators and electron microscopes. Analogies are drawn between a quantum wave packet and a classical beam of many particles in phase space, including the calculation of mean emittance of the NSLG state as a measure of its quantum nature.

Speaker: Ilia Pavlov (ITMO University)

14:00 Novel photoinjector laser providing advanced pulse shaping for FLASH and EuXFEL

We recently commissioned the Next GenerAtion Photocathode Laser system (NEPAL) in Hamburg’s XFEL facilities (FLASH and EuXFEL) and at DESY’s Photoinjector Test Facility (PITZ). The system delivers deep UV pulse trains up to 1 ms long at repetition rates as high as 4.5 MHz, with temporal and spatial shaping capabilities and individual amplitude control for bunch charge manipulation. The shaping features enable the generation of exceptionally low emittance electron beams, essential for extending the EuXFEL X-ray photon energy beyond 25 keV and for future high duty cycle upgrades. Temporal shaping is achieved through a high-resolution spatial light modulator in the near-infrared driver laser, allowing precise spectral amplitude and phase control of UV pulses. We will present advanced control schemes that pre-compensate for laser nonlinearities and initial experimental results at EuXFEL. We generated UV flat-top pulse profiles with durations ranging from 10ps to 20ps and successfully transferred them onto the electron beam. This achievement represents a significant step toward emittance optimization at EuXFEL and will expand the facility's operational energy range in the near future.

Speaker: Denis Ilia (Deutsches Elektronen-Synchrotron DESY)

14:00 Operational results of data-driven automated intensity optimization at CERN’s LEIR

At CERN’s Low Energy Ion Ring (LEIR), high beam intensities are achieved through phase space painting with up to eight multi-turn injections from the linear accelerator Linac3. After each injection, the beam is cooled and stacked in longitudinal phase space using an electron cooler. During beam operation, key parameters such as RF cavity phases in the linac, the LEIR electron cooler gun voltage, and various magnetic field strengths along the transfer line must be frequently adjusted to compensate for the injection performance degradation occurring over time. The primary cause is the aging of the stripper foil, a thin carbon plate which strips off electrons from the passing ions, altering the energy of the beam injected from the linac. Time of flight measurements in the linac and Schottky signals in the ring provide the necessary diagnostics for correcting the performance degradation and can be encoded to provide a state for an optimizer. In this paper, we compare several data-driven methods, such as Bayesian Optimization and Reinforcement Learning for designing an autonomous controller to optimize and maintain injection performance during both beam commissioning and physics runs.

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

14:00 Optimization of the Korea-4GSR storage ring for increasing the off-momentum dynamic aperture by analyzing resonance driving terms

The Korea-4GSR is a next-generation diffraction-limited light source designed to provide beam brightness up to 100 times greater than existing facilities. Chromatic aberrations from strong focusing fields in quadrupoles are corrected using sextupoles and octupoles. However, these sextupoles and octupoles introduce nonlinear effects, causing electrons to follow nonlinear trajectories, ultimately reducing beam lifetime. Consequently, these nonlinear elements negatively impact both the dynamic aperture and local momentum aperture. The limitations on local momentum aperture are primarily due to transverse nonlinear dynamics. Recent studies have shown that minimizing one-turn resonance driving terms, reducing their fluctuations, or controlling amplitude-dependent tune shifts (ADTS) can enhance both dynamic aperture and local momentum aperture in various storage ring configurations, including DBA, MBA, and hybrid-MBA lattices. Therefore, we aim to optimize resonance driving terms using a Multi-Objective Genetic Algorithm (MOGA) to expand on- and off-momentum dynamic apertures and improve beam lifetime by increasing local momentum aperture for the Korea-4GSR.

Speaker: Junha Kim (Pohang Accelerator Laboratory)

14:00 Optimizing collimator positions using bayesian optimization in the Fermilab MI-8 transfer line

Collimators are used to minimize losses and to remove particles that would otherwise get lost downstream and irradiate the machine. Finding the optimal jaw positions is time consuming and with the upstream beam properties changing, the collimation settings would need to be readjusted each time. Therefore, a method to optimize collimator positions and to operate them at full capacity in a short time is required for loss control downstream. A study of collimator positions was conducted and a machine learning (ML) model was developed to predict optimal collimator positions. Bayesian Optimization (BO) was used to calculate new jaw positions from the ML model. The results of BO and usage of ML for better performance of the collimation system are presented in this paper.

Speaker: Betiay Babacan (Fermi National Accelerator Laboratory)

14:00 Optimizing multi-turn extraction at CERN using transverse feedback

Initial experimental investigations of transverse beam splitting, carried out at the CERN Proton Synchrotron, have demonstrated that transverse feedback is highly effective in controlling the characteristics of the transversally split beam. The feedback notably improves the intensity distribution among the beamlets and the emittance of the core, which is the portion of the beam remaining near its centre after the resonance-crossing process. The transverse feedback is set in resonance with the horizontal betatron tune while the tune crosses the fourth-order resonance, creating a double-resonance condition. A simple Hamiltonian model has been employed to explore the underlying double-resonance mechanism. This paper thoroughly examines detailed numerical simulations based on a realistic lattice model alongside beam measurements, to identify optimisation strategies for the use of transverse feedback in controlling the properties of split beams.

Speaker: Oleksandr Naumenko (European Organization for Nuclear Research)

14:00 Preliminary commissioning results of the LW prototype at CSNS

China Spallation Neutron Source (CSNS) accelerator complex will employ a new superconducting accelerating section to provide high beam power. To prevent contamination of the superconducting cavity surface caused by sputtering, shedding, or melting of medium materials during interceptive beam measurements, the second phase of the China Spallation Neutron Source (CSNS) superconducting linac section will adopt laser stripping technology for transverse distribution measurements of the negative hydrogen beam at nine stations. This paper describes the design of LW prototype including laser parameters, optics transmission and simulation of laser-beam interaction. And the preliminary results of the profile measurement where beam energy is 80MeV are also presented.

Speaker: Biao Zhang (Institute of High Energy Physics)

14:00 Preliminary electromagnetic design of a high-temperature superconducting superbend for the Hefei Advanced Light Facility

The National Synchrotron Radiation Laboratory is constructing a 2.2 GeV diffraction-limited storage ring, the Hefei Advanced Light Facility (HALF), using the modified hybrid 6BA lattice, which consists of a total of 20 cells. The synchrotron radiation primarily covers the vacuum ultraviolet (VUV) to soft X-ray bands. To extend the photon energy into the hard X-ray range, two 0.9 T normal-conducting bending magnets are to be replaced with 6 T superconducting magnets. This upgrade demands a magnet that achieves high magnetic field strength while seamlessly integrating with the storage ring's compact geometry and operational constraints. The C-shaped yoke design allows the magnet to be easily inserted and removed from its position in the storage ring vacuum chamber. The coil is planned to be wound with ReBCO tape due to its higher current-carrying capacity and critical temperature. This paper discusses the design requirements of the superbend and presents two electromagnetic design schemes.

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

14:00 Preliminary investigation on single-pixel Schottky diode based ultra-broadband THz detectors with ps-scale temporal resolution for future BCMs

A Terahertz (THz) transition radiation monitor, as part of a Bunch compression monitor (BCM), is implemented for longitudinal bunch diagnostics at FELs such as ELBE, FLASH, or EuXFEL. Pulse energy measurements are typically carried out after each bunch compressor stage using coherent diffraction radiation (CDR) in the THz domain and pyroelectric detectors. For higher repetition rates in the MHz range, complex correction algorithms must be applied to correct signal pileup of the pyro-electric detector output, as well as limited signal-to-noise ratio, which can be overcome by using THz detectors with ultra-flat frequency response up to several THz. This work exhibits preliminary studies on developing an ultra-flat frequency response THz spectrometer. We present the developed single-pixel Schottky diode-based THz detector capable of single-shot measurements with a response time of 28.5 ps and IF bandwidth of $\sim$70 GHz. Further, the simulation result from the Schottky diode parameters is presented.

Speaker: Mr Rahul Yadav (Technical University of Darmstadt)

14:00 Preliminary study on the collective effect in a high-current and low-energy storage ring

High-current and low-energy storage ring is an essential part of accelerator for industrial application. However, high intensity poses great challenge to beam stability through collective effects, which can be exacerbated at low energy. In this paper, we present a preliminary study on various collective effects in an application-oriented storage ring. The classical theory is reviewed, and numerical analysis is performed on Touschek scattering, intra-beam scattering, resistive-wall, beam-ion and so on. In addition, Particle tracking is carried out using elegant, mbrack2, etc. Lastly, techniques to improve the current threshold are also discussed.

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

14:00 Progress towards longitudinal bunch profile monitor at the Argonne Wakefield Accelerator employing phase diversity electro-optic sampling

Precise measurement of an electron bunch’s longitudinal profile is critical for wakefield accelerators as shaped electron bunches can improve transformer ratios in collinear wakefield acceleration. Electro-Optic sampling of terahertz (THz) radiation from the bunch is one of the most attractive approaches to provide a view into the structure of a relativistic electron bunch due to its non-destructive nature. Recent developments in spectral encoding methods have shown that Phase Diversity Electro-Optic Sampling (DEOS) can accurately retrieve profiles from both sub-picosecond bunches and those requiring long sampling time windows near the traditional resolution limits. We report the progress on DEOS measurements using coherent transition radiation (CTR), as well as simulations of retrieved THz fields from arbitrary shaped electron bunches using various crystal and probe-laser configurations.

Speaker: Spencer Kelham (Northern Illinois University)

14:00 Real-time luminosity optimization in collider experiments using reinforcement learning

This study presents the development and implementation of a reinforcement learning-based algorithm for real-time luminosity tuning in collider experiments. The algorithm is initially pretrained on historical collider data and subsequently fine-tuned online during experiments. By analyzing accelerator measurements collected over several seconds, the model adjusts the magnetic structure to stabilize luminosity under varying experimental conditions. The proposed method allows for adaptive optimization without operator involvement, improving operational efficiency and stability. Results from its application on the VEPP-4M collider are presented, showcasing the method's feasibility and offering insights for its future development and application in accelerator systems.

Speaker: Rasim Mamutov (Russian Academy of Sciences)

14:00 Recent developments in delivering mixed helium and carbon ion beams for online treatment monitoring research at MedAustron

Simultaneous irradiation with mixed helium and carbon ions is being proposed for online range verification in carbon radiotherapy. In 2024, a mixed $^4$He$^{2+}$ and $^{12}$C$^{6+}$ beam, generated by sequential injection of helium and carbon ions into the synchrotron, was extracted successfully for the first time at the MedAustron ion beam therapy and research center. This double injection scheme comes with challenges concerning the capture, acceleration, and slow extraction, as injection energy offsets and differences in horizontal phase distributions have to be considered in addition to the small offset in charge-to-mass ratio between $^4$He$^{2+}$ and $^{12}$C$^{6+}$. This proceeding reports on recent developments in the delivery of this mixed ion beam at MedAustron using a double injection scheme, which includes an additional deceleration ramp for helium ions between the injections of helium and carbon, as well as progress towards a measurement setup for the time-resolved quantification of the ion mixing ratio at delivery.

Speaker: Matthias Kausel (EBG MedAustron GmbH)

14:00 Resonance Driving Terms characterization at VEPP-2000 collider

The VEPP-2000 collider is a compact machine, which uses the round-beam concept to achieve high luminosity. Its compact size (24 m in circumference) limits the free space between the magnetic elements. Only 4 BPMs are installed in the ring with large phase advance between them (~2 pi). The key to improve its luminosity is to reduce the power of resonances. The implementing of the RDT measurement technique with our limitations is discussed. The presented experimental data gives basic information on the location of the considered magnetic perturbation causing the RDT.

Speaker: Danil Chistiakov (Russian Academy of Sciences)

14:00 RF design for a quadrupole resonator with a fundamental frequency of 325 MHz at IMP

The Quadrupole Resonator (QPR), originally developed at CERN, is a dedicated radio-frequency characterization equipment for evaluating superconducting material. It employs the calorimetric compensation technique and has a surface resistance resolution of less than 1 nOhm, operaing over a wide range of parameters, such as tem-peratures, resonant frequencies and magnetic fields. As a part of R&D work of superconducting material for SRF application in particle accelerators. A QPR with operating frequency of 325 MHz has been developing at Institute of Modern Physics (IMP), CAS. In this paper, we present the detailed electromagnetic design of the QPR, the design focuses on reducing the risk of multipacting, field emis-sion (B_pk/E_pk) and mode overlapping (delta f = f_QPR-f_dipole), enhancing the attainable peak magnetic field (B_sample/B_pk). The electromagnetic simulation results indicate that the optimized structure has good electromagnetic performance. Additionally, the coupler design compatible with four QPR modes will be introduced. The cavity will be fabricated soon.

Speaker: Yong Zhao (Institute of Modern Physics, Chinese Academy of Sciences)

14:00 Searches for RF breakdown precursors using Cherenkov light in optical fibers

RF breakdown studies are crucial for machines relying on high-gradient, normal-conducting RF accelerating cavities. Searches for breakdown precursors in high-gradient test-stand data have been conducted and highlight the need for a new diagnostic with improved temporal response. Emission of Cherenkov light in optical fibers has been identified as one such diagnostic**, which occurs when charge showers due to breakdown are incident on the fiber.

Optical fibers have been used previously as distributed Beam Loss Monitors. At the X-Band Laboratory for Accelerators and Beams (X-LAB), we position optical fibers adjacent to X-band cavities being conditioned for the proposed Compact Linear Collider (CLIC). We assess sensitivity of fibers to charge emitted by field emission and breakdown events. Since breakdown precursors may occur at sub-microsecond timescales**, we survey photon detectors best suited to examining fiber response and identifying precursors. We compare fiber signals to dark current captured by upstream and downstream Faraday Cups. In search of precursory phenomena, pulse-by-pulse evolution of fiber signals is examined for field-emission activity prior to breakdown.

Speaker: Paarangat Pushkarna (The University of Melbourne)

14:00 Selecting optimal views for tomography reconstruction

Previous works on reconstructing the 4D phase space using tomography require optimal selection of projection views to achieve accurate reconstruction. In 2D reconstruction, the process is straightforward, as an object can be evenly sampled by dividing the angles evenly. However, extending this concept from 2D to 4D is not intuitive. This work demonstrates that quaternions can be used to more effectively describe views in 4D and introduces the Fibonacci Flower algorithm and repulsive force algorithm to evenly space views in 4D space in order to achieve higher reconstruction accuracy.

Speaker: Anthony Tran (Facility for Rare Isotope Beams)

14:00 Service-oriented EPICS and data processing method based on high-availability cluster

A novel service-based EPICS and new front-end data acquisition method based on a high-availability Kubernetes cluster built on the Proxmox VE platform are proposed in this paper to enhance the performance and stability of the data acquisition system. By deploying EPICS services on the Kubernetes cluster, a new efficient front-end data processing and acquisition method is realized. The data acquisition method utilizes distributed data sharing based on the Channel Access protocol to perform real-time processing and analysis of data. This approach offers advantages such as reducing hardware and maintenance costs, improving portability and flexibility, and enhancing data acquisition and processing efficiency. The practical application and testing have demonstrated that this method has the potential for use in large scientific facilities. In the future, its application value in other fields will be explored.

Speaker: Dr Yukun Li (Institute of High Energy Physics)

14:00 Simultaneous electron beam acceleration and compression with a radiofrequency cavity in ultrafast electron diffraction experiments

In ultrafast electron diffraction experiments, the scattering cross-section, q-range, and space-charge effects are critically influenced by the electron beam energy, which is constrained by the high-voltage breakdown. By integrating a 100 kV DC electron gun with a 3 GHz radiofrequency cavity powered with a 400 W amplifier, we demonstrate a net energy gain of up to 31 keV. Here we present simulation and experimental results highlighting the simultaneous compression and accelerating capabilities using a radiofrequency cavity, demonstrating that significant energy gains are attainable without compromising femtosecond scale time resolution.

Speaker: Linus Bölte (TU Dortmund University)

14:00 Sputtering characteristics of a compact NEG-coating device and performance evaluation of the TiZrV thin films

Non-evaporable Getter (NEG) coating is a breakthrough technology wherein the inner walls of a vacuum chamber are coated with a material that functions as a vacuum pump. This technology is expected to gain widespread adoption across various fields in the future. However, the current coating method, originally developed for long beam ducts, is not adaptable to a wide range of vacuum chamber designs. Therefore, we have developed a compact NEG coating device that can be adapted to chambers of various geometries. The primary advantage of this device is its ability to coat complex-shaped chambers, which was difficult with conventional methods. Additionally, by reducing the uncoated surfaces as much as possible, it significantly improves pumping performance in terms of pumping speed and reducing Photon Stimulated Desorption (PSD) yields. We explore the optimal sputtering conditions for depositing high-performance NEG thin films with the device, and have performance evaluations of the NEG films, with observing the morphologies, measuring the pumping speed and PSD yields.

Speaker: Ruau Watanabe (The Graduate University for Advanced Studies, SOKENDAI)

14:00 Status of the RF system design for the SC240 cyclotron

The superconducting cyclotron SC240 is used to accelerate proton beams to 240 MeV for proton therapy. The SC240 is an isochronous 4 sectors compact cyclotron with a central magnetic field of 2.5 T. Particles acceleration is performed under the second harmonic mode of the radio-frequency (RF) system, consisting of two independent cavities located in the cyclotron valleys. Block on the chimney is designed to avoid interference between two cavities. The isolation (S21) is less than -30dB. In cavities, two types of tuners applied to compensate for frequency offset are tuning loop and trimmer plate. The tuning frequency range of tuning loop is more than 1MHz, that can be used to adjust the frequency offset caused by machining error and installation error during cold test, rather than caused by thermal deformation when feeding high power into cavities, While the trimmer plate is just used in the opposite way. Efficiency of acceleration voltage in center region caused by different ground position of ion source is presented in the paper. Design and optimization of inductive coupler are described in details. Besides, the current operating status of the RF system will also be discussed.

Speaker: Gen Chen (Institute of Plasma Physics)

14:00 Substrate material studies for PCB-based electro-optical bunch arrival-time monitors for XFELs

The all-optical synchronization system used in many X-ray free-electron laser facilities (XFELs) relies on electro-optical bunch arrival-time monitors (EO-BAM) for measuring the single bunch arrival-time with regards to an optical reference. An upgrade of the established EO-BAM is intended to achieve a sensitivity that enables stable operation with bunches down to charges of 1 pC or significantly increase the resolution in normal operation. Therefore, the pickup structure, the RF path and the electro-optical modulators are undergoing a fundamental redesign. The novel concept of the pickup structure comprises planar pickups on a printed circuit board (PCB) with integrated combination network and a bandwidth of up to 100 GHz. The theoretical jitter charge product of the preliminary concept has been estimated to be in the order of 9 fs pC and the concept was proven experimentally with a 67-GHz demonstrator at ELBE. In this contribution, we compare ceramic and glass substrates in terms of radiation hardness, sensitivity, and manufacturing capabilities. The achievable bandwidth and sensitivity are influenced by material losses and varying tolerances due to different fabrication methods.

Speaker: Mr Bernhard Scheible (Technische Hochschule Mittelhessen)

14:00 Superconducting β=0.19 half-wave cavity for CiADS

A 162.5 MHz, optimal beta = 0.19 pure niobium half-wave resonator (HWR) called HWR019 for the superconducting driver linac of the China initiative Accelerator-Driven subcritical System (CiADS) has been designed and analyzed at the Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS). The linac requires 24 HWR019s to accelerate protons from 6.8 MeV to 45 MeV. This paper mainly presents a design scheme of HWR019. Meanwhile, electromagnetic field optimization, and mechanical structure design are carried out, to predict the behavior of the cavity under practical operating process. At present, this superconducting cavity has been fabricated a prototype and awaits further testing.

Speaker: Mr Zehua Liang (Institute of Modern Physics, Chinese Academy of Sciences)

14:00 The contribution of multiple reflections to transition radiation

A uniformly moving electron passing through a slab induces electromagnetic
emission known as transition radiation. The generated rays propagate inside
the slab and undergo multiple reflections off the slab boundary. We employ the polarization current method in order to derive the reflectionless
solution for an observed radiation intensity and compare it with that of Pafomov
which accounts for multiple reflections exactly. We identify the parameters of the set up that reduce the Pafomov solution to a reflectionless scenario. Provided the ultrarelativistic electron, the proper choice of the slab thickness allows the consideration of the reflectionless solution even in the optical range. Furthermore, it is shown that in the x-ray regime the reflections only become substantial when the radiation is incident on the slab boundary at a high angle at which the intensity of the radiation is vastly reduced. Therefore for a slab shaped screen the reflections may be ignored. Nevertheless the identification of the scenarios where reflectionless solution deviates from the Pafomov, could be used to qualitatively describe transition radiation from targets of complex shape.

Speaker: Dmitrii Grosman (ITMO University)

14:00 The study of a tunable double-ring permanent magnet focusing device for low-energy electron acceleration

This study addresses the insufficient focusing force in solenoid focusing devices for low-energy electron accelerators, which leads to beam spot precision issues. A tunable double-ring permanent magnet focusing device based on the Halbach structure is proposed. The use of octagonal magnets replaces traditional sector magnets, avoiding the issue of differing magnetization directions. The effects of the radius of the octagonal magnets, aperture, mechanical length, and the rotation angles of the inner and outer magnetic rings on the magnetic field gradient and higher-order harmonics are analyzed. Optimal structural parameters lead to a double-ring magnet structure with a good field radius greater than 20 mm and higher-order harmonic content below 1.5%. By rotating the magnetic rings, a continuous adjustable magnetic gradient from 0.1 T to 1.5 T is achieved. The effective length and magnetic gradient of each lens unit are iterated using TraceWin software, successfully reducing the beam spot size of a 60 kV/10 mA electron beam from 4 mm to 500 μm. The focusing performance was verified through CST software simulations, providing an effective solution for low-energy electron accelerators.

Speaker: Zhenyi Zhang (Huazhong University of Science and Technology)

14:00 Thresholds of longitudinal multi-bunch instabilities in double harmonic RF systems

Multi-bunch instabilities, often driven by narrowband impedance sources such as higher-order modes, present significant intensity limitations in synchrotrons. One approach to mitigate these instabilities is applying a double harmonic radio frequency (RF) system, which can increase the intensity threshold by enlarging the synchrotron frequency spread. In this study, intensity thresholds are calculated for different RF parameters using stability diagrams derived from the Lebedev equation. We analysed configurations and beam characteristics relevant to the synchrotrons at CERN, particularly focusing on the Super Proton Synchrotron (SPS). The semi-analytical results were then compared to macroparticle simulations and measurements. The findings reveal an unexpected beam stabilisation even if a non-monotonic amplitude dependency of the synchrotron frequency is present. Further, techniques for deducing the driving impedance parameters are discussed.

Speaker: Ruben Heine (European Organization for Nuclear Research)

14:00 Touschek lifetime and periodic beam loading effect in the storage ring of SRF "SKIF"

The collective effects observed in storage rings with high-intensity beams are numerous and diverse. One such effect is that of periodic beam loading of accelerating RF cavities. This effect is contingent upon the impedance of the fundamental mode of the RF cavities and the mode of filling pattern. In a multitude of configurations, the periodic beam loading effect in storage rings leads to a change in the Touschek lifetime along the beam. This work is dedicated to the calculation of this effect in the storage ring of SRF "SKIF", a novel fourth-generation synchrotron radiation source currently under construction in Novosibirsk. Analytical calculations of this effect have been carried out for the main filling mode of the storage ring. It has been demonstrated that bunches in this regime can exhibit significantly disparate Touschek lifetimes. Furthermore, it has been shown that the effect is negligible when the RF acceptance is equal to the energy acceptance of the storage ring.

Speaker: Mikhail Baistrukov (Budker Institute of Nuclear Physics)

14:00 Towards Improving luminosity using optics tuning and data-driven methods

The results of Run 24 experiments at Relativistic Heavy Ion Collider (RHIC) for improving luminosity using optics tuning are presented in this study. In the first experiment, MADx matching was used to output magnet strengths corresponding to specific s star movements around Interaction Region 8 (IR8). The corresponding Zero Degree Calorimeter (ZDC) signal was measured in place of luminosity, and Bayesian Optimization aids search of optimal movements. It was found that values retrieved from matching were inaccurate, resulting in negative feedback loops. The second experiment focused on calculating accurate s star movements. The matching method was replaced with a linear sensitivity matrix, directly relating optics to power supply, and its null space was used to fit constraints such as hysteresis effects. At the experiment, beam losses were observed at collimators around boundary of IR8, which were fixed for the third experiment. Dynamic mode decomposition was also introduced to improve quality of turn-by-turn (TBT) data as well as accuracy and consistency of optics measurements at IR8. These improvements will be tested in the experiment of next RHIC run for luminosity optimization.

Speaker: William Fung (Facility for Rare Isotope Beams)

14:00 Transient finite-element simulations of fast-ramping normal-conducting magnets for a 10 TeV muon collider

Ongoing conceptual studies for a 10TeV muon collider identified rapid cycling synchrotrons as major engineering challenge. Due to the muon’s short lifetime of only 2.2µs at rest, normal-conducting bending magnets with field rise rates of well beyond 1kT/s are indispensable to support accordingly fast acceleration cycles. Energies of 100MJ will be interchanged between magnets and capacitor banks within few milliseconds. Accurate models of the magnets are thus required to optimize the overall system performance. The non-uniform temperature distribution in the magnet strongly affects material properties like the electrical conductivity of copper and must therefore be considered in the electromagnetic field problem. This contribution presents recent advancements in addressing this multi-physical problem by using problem-specific finite-element tools allowing to describe the inherently transient behavior. The ferromagnetic yoke is accurately resolved by using a novel combination of a Bergqvist hysteresis and a homogenized eddy current model. Finally, different magnet design concepts are compared in terms of material costs, magnetic energy, losses, field quality and temperature buildup.

Speaker: Dominik Moll (Technical University of Darmstadt)

18:00 → 20:30 Welcome Reception

Monday 2 June

09:00 → 09:30 Opening

LOC1_talk.pdf

09:25 Practical Information from the LOC

Speaker: Jui-Che Huang (National Synchrotron Radiation Research Center)

09:30 → 10:30 Plenary Before Coffee

Convener: Ming-Chyuan Lin (National Synchrotron Radiation Research Center)

09:30 The operational challenges: Achieving 500 mA high beam current at Taiwan Photon Source

The Taiwan Photon Source (TPS) has been in routine operation at 500 mA since the last season of 2021, utilizing two superconducting cavities, bunch by bunch feedback system, and fast orbit feedback system, along with many technical efforts. The operation of TPS maintains its high reliability and availability. The mean time between failures is more than 190 hours with an availability greater than 98.9% in 2023. With newly developed cryogenic permanent magnet undulators, IVUs, and EPUs, balancing the needs of both soft X-ray and hard X-ray users. Many challenges have been encountered in the journey to achieving a beam current of 500 mA, primarily due to the short bunch length of 16 ps and impedance issues in vacuum chambers at TPS storage ring. Ongoing efforts to improve the performance and the detailed journey to achieving 500 mA top-up operation will be presented.

Speaker: Ping Chou (National Synchrotron Radiation Research Center)

10:00 High-beam-power operations at heavy ion facilities: Technical developments, challenges and resolutions

Today, new heavy ion accelerator facilities are emerging worldwide, including FRIB in the United States, RAON in Korea, HIAF in China, and FAIR in Germany. While each facility features distinct accelerator configurations, they share a common goal: advancing nuclear science through the acceleration of intense heavy ion beams. Among these, the RIKEN RI Beam Factory (RIBF) in Japan has led the way, commencing operations in 2007 as the first of the new-generation facilities. Based on a multi-stage cyclotron system with the superconducting ring cyclotron (SRC) as its final stage, RIBF accelerates heavy ions, including uranium, to 345 MeV/u and produces rare isotope beams using an in-flight scheme. Over 15 years of operation, RIBF has achieved significant advancements in beam intensity and stability, with beam power from the SRC now reaching 10 - 20 kW. These improvements have enabled groundbreaking studies of unstable nuclei. This presentation will discuss the technical challenges overcome at RIBF, and explore the facility’s future directions in heavy ion acceleration.

Speaker: Osamu Kamigaito (RIKEN Nishina Center)

10:30 → 11:00 Coffee Break

11:00 → 12:30 Plenary after coffee

Convener: Tadashi Koseki (High Energy Accelerator Research Organization)

11:00 Review of nonlinear resonances in acclerators and storage rings

Review of nonlinear resonances in accelerators and storage rings; including a discussion of chaos, particle diffusion and dynamic aperture

Speaker: Shyh-Yuan Lee (Indiana University)

11:30 Liquid lithium charge stripping technology: Achievement and lessons learned

Liquid metal technology is key to the next-generation high-power hadron facilities. Following early R&D collaboration between Argonne National Laboratory and Michigan State University, FRIB pioneered the technology of liquid lithium thin film and is the first in the world applying such technology in accelerator operations. FRIB uses a liquid lithium film for the charge stripping of high-power heavy-ion beams, enabling FRIB to achieve world’s highest power uranium beam on target.
Liquid lithium technology has been successfully applied to the liquid lithium charge stripper for FRIB operations, offering a superior choice for charge stripping of high-power heavy ion beams including uranium. Valuable experience has been gained in the performance and maintenance. This talk focuses on operational experience, lessons learned and future improvements.

Speaker: Takuji Kanemura (Facility for Rare Isotope Beams)

12:00 RF acceleration with short pulses: Breaking the high-gradient barrier

Achieving high-gradient acceleration is critical to enabling future linear colliders, free-electron lasers, and other compact accelerator applications. The Argonne Wakefield Accelerator (AWA) group has pioneered short-pulse structure wakefield acceleration technology, which has shown remarkable promise for surpassing the long-standing barrier of ~100 MV/m in X-band normal-conducting structures. Recent experiments have demonstrated the feasibility of this approach, with gradients exceeding 300 MV/m in a variety of X-band accelerating structures and an X-band photogun. Experimental results indicate that the empirical scaling law used to estimate the RF breakdown rate (BDR ~ E^30 * t^5) may be too conservative for RF pulse durations below 10 ns. Potential advanced accelerator designs based on short-pulse acceleration will also be presented, including a conceptual design for an ultra-compact XFEL.

Speaker: Xueying Lu (Northern Illinois University, Argonne National Laboratory)

12:30 → 14:00 Lunch

14:00 → 15:00 MOZD: Colliders and Related Accelerators (Invited)

Convener: Ryoichi Hajima (National Institutes for Quantum Science and Technology)

14:00 ILC accelerator status

The international linear collider (ILC) is a Higgs Factory, where electron-positrons are accelerated by the linear accelerators using Superconducting RF (SRF) cavities to 125 GeV. In 2013, the GDE, an international organization of researchers, already compiled the TDR. It is currently being studied under the International Development Team (IDT). Especially, from 2023, the ILC Technology Network (ITN), specifically under the IDT, will work on the development through international cooperation. This presentation will show an overview of the ILC and the recent developments under the ITN. First, an overview about the latest proposed Higgs factories of more than 250 GeV energy will be given. Second, we introduce the ILC accelerator, including the design, key technologies, accelerator systems. Finally, an detailed ongoing key technology developments, such as SRF cavities, nanobeam, and sources, for ILC project over the next few years will also be presented. We believe that these accelerator developments are not only crucial for ILC development but also for the improvements of future accelerators and various industrial and medical applications.

Speaker: Hiroshi Sakai (High Energy Accelerator Research Organization)

14:30 Status of the baseline design for a 10 TeV 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. Also initial studies of possible sites are included.

Speaker: Daniel Schulte (European Organization for Nuclear Research)

14:00 → 15:00 MOZN:Accelerator Technology and Sustainability (Invited)

Convener: Zong-Kai Liu (National Synchrotron Radiation Research Center)

14:00 Overview of permanent magnet implementations for advanced light sources

The utilization of permanent magnets in the design of accelerator magnets has witnessed a surge in prominence, particularly within the realm of advanced light sources. Following pioneering initiatives at SIRIUS and ESRF-EBS, current projects are increasingly embracing permanent magnet technology. Notably, in the case of SLS2.0, over 30% of the magnets in the new storage ring are powered with permanent magnets. Permanent magnets offer manifold advantages, including compactness, much simpler requirements in terms of services (such as power supplies, cables, and cooling systems), and reduced operational costs. Nonetheless, they also present significant challenges that demand careful consideration. In this study, the author provides an overview of permanent magnet implementations across various projects and delves into a detailed analysis of the Swiss Light Source upgrade.

Speaker: Dr Ciro Calzolaio (Paul Scherrer Institute)

14:30 Development for various applications at compact ERL as a high-power CW SRF linac in KEK

It is about “Development for Various Application at Compact ERL as a high-current CW SRF linac in KEK”. As an introduction, the author will talk about the merit of the superconducting RF (SRF) cavity and also talk about our applied research based on Compact ERL (cERL) in KEK, which uses the Nb superconducting cavity and can make energy recovery operation. The cERL's characteristic using the high-current beam has the variety of applications; industrial applications using high-intensity terahertz light and mid-infrared FEL (free-electron laser). In addition, the high current CW beam irradiation was conducted for basic research on domestic production of nuclear medicine, strengthening of asphalt, and the highly efficient production of nanocellulose from wood in cERL. After talking these applications of cERL, next we will talk about “Future plan for applied research using superconducting accelerators”. One is the EUV-FEL light source development for EUV-lithography and the other is the development of compact superconducting RF accelerator based on Nb3Sn for high-power beam irradiation.

Speaker: Masahiro Yamamoto (High Energy Accelerator Research Organization)

15:00 → 16:00 MOCD:Colliders and Related Accelerators (Contributed)

Convener: Ryoichi Hajima (National Institutes for Quantum Science and Technology)

15:00 Updated baseline design for HALHF: the hybrid, asymmetric, linear Higgs factory

Plasma accelerators promise significantly more compact, affordable and greener next-generation facilities, including linear colliders. While high-efficiency and -quality plasma acceleration of electron beams has been achieved, positron beams are much more challenging. The HALHF* (hybrid, asymmetric, linear Higgs factory) collider concept sidesteps the positron problem by accelerating them using RF cavities, while plasma acceleration to much higher energy is utilised for electrons. We report on an updated HALHF baseline design, which is more realistic, more upgradable to higher energies and includes additional capabilities such as positron polarization. Preliminary start-to-end simulations of the new baseline are also described.

Speaker: Erik Adli (University of Oslo)

15:20 Future e+e- colliders using recycling Energy-Recovery Linacs

I will discuss potential offered by Energy-Recovery Linacs (ERLs) and particle recycling for boosting luminosity to 1E37 cm-2sec-1 level in TeV-scale electron-positron colliders. ERL-based colliders have promise not only of significantly higher luminosity, but also of higher energy efficiency measured in units of luminosity divided by the consumed AC power. Addition of recycling collided particles and their recuperations in damping ring removes insane ILC/CLIC appetite for fresh positions, offers high degrees of polarization in colliding beams as well as possibility of eliminating problems associated with beamsstrahlung.
Two examples of ERL-based factory located in LHC and FCC tunnels will be compared with well-known linear ERL collider projects: ILC and CLIC.
I will finish with discussion of possible technical breakthroughs which can make such recycling linear colliders more affordable and even more attractive.

Speaker: Vladimir Litvinenko (Stony Brook University)

MOCD2_talk.pdf

MOCD2_talk.pptx

15:40 Observations and efforts to reduce sudden beam loss at SuperKEKB

The SuperKEKB accelerator recorded a peak luminosity more than twice that of the KEKB accelerator, but there are various challenges in updating the luminosity beyond that. One of the challenges is to eliminate sudden beam loss (SBL), in which a significant part of the circulating beam is lost in a few short turns. SBLs of the positron ring were investigated and found that the SBLs are characterized by vacuum pressure bursts at specific locations in the ring and an increase in beam size. From these measurements, it can be inferred that some phenomenon occurred at the location where the pressure burst was occurring, causing the beam size to increase and the beam to be lost in the narrow aperture of the ring. We performed knocker tests to artificially cause SBL and looked for possible sources of SBL. Based on several assumptions, we performed several works, including swapping the chamber up and down, cleaning the inside of the chamber, and knocking the chamber before operation. Of these works, the cleaning inside the chamber was found to be likely to be effective. This paper summarizes the measurement of SBL when it occurred and the countermeasures that contributed to its reduction.

Speaker: Hitomi Ikeda (High Energy Accelerator Research Organization)

15:00 → 16:00 MOCN:Accelerator Technology and Sustainability (Contributed)

Convener: Zong-Kai Liu (National Synchrotron Radiation Research Center)

15:00 Nb3Sn cavity development based on vapor deposition method at KEK

Nb$_{3}$Sn is one of the most promising materials for the next generation of superconducting RF (SRF) cavities. One key advantage is that Nb$_{3}$Sn cavities can achieve high Q-values at 4 K, whereas conventional Nb cavities require cooling to 2 K. This enables the operation of SRF cavities using conduction cooling, thereby eliminating the need for liquid helium, unlike conventional SRF cavities that require immersion cooling. Since around 2019, KEK has been conducting Nb$_{3}$Sn deposition tests on single-cell cavities using the Sn vapor diffusion method and has steadily improved cavity performance. Additionally, a small deposition furnace dedicated to sample studies was constructed to investigate the relationship between Nb$_{3}$Sn film quality and deposition parameters. In this presentation, we will report the results of sample deposition tests and RF measurements of single-cell Nb$_{3}$Sn cavities.

Speaker: Hayato Ito (High Energy Accelerator Research Organization)

15:20 Recent developments in the accelerator equipment automation field

CERN has embarked on a new programme of Particle Accelerator Efficiency improvements that is inspired by lessons learned from the last years of operation and by the latest technology advancements. The field of equipment automation is being addressed through a mix of concrete developments and pilot projects. This paper presents the work on preparing a new paradigm of accelerator equipment automation and reporting, anomaly detection and advanced analysis for predictive maintenance. An example of such automation is presented using the case of the SPS injection kicker (MKP) and the automatic classification of vacuum spike events to provide additional context to experts and stand-by personnel during interventions on the installation. This contribution also outlines how Kicker magnet faults caused by high voltage electrical discharge events can be distinguished from standard vacuum spike events, thus allowing a rapid automatic recovery without expert interventions.

Speaker: Konstantinos Papastergiou (European Organization for Nuclear Research)

15:40 Searches for RF breakdown precursors using Cherenkov light in optical fibers

RF breakdown studies are crucial for machines relying on high-gradient, normal-conducting RF accelerating cavities. Searches for breakdown precursors in high-gradient test-stand data have been conducted and highlight the need for a new diagnostic with improved temporal response. Emission of Cherenkov light in optical fibers has been identified as one such diagnostic**, which occurs when charge showers due to breakdown are incident on the fiber.

Optical fibers have been used previously as distributed Beam Loss Monitors. At the X-Band Laboratory for Accelerators and Beams (X-LAB), we position optical fibers adjacent to X-band cavities being conditioned for the proposed Compact Linear Collider (CLIC). We assess sensitivity of fibers to charge emitted by field emission and breakdown events. Since breakdown precursors may occur at sub-microsecond timescales**, we survey photon detectors best suited to examining fiber response and identifying precursors. We compare fiber signals to dark current captured by upstream and downstream Faraday Cups. In search of precursory phenomena, pulse-by-pulse evolution of fiber signals is examined for field-emission activity prior to breakdown.

Speaker: Paarangat Pushkarna (The University of Melbourne)

16:00 → 18:00 Monday Poster Session: MOPB

16:00 A novel design of a magnetic chicane with positive R56

It has been attracting attention that the energy chirp, which is formed by the space-charge effect of the electron beam and the beam wake field when the beam passes through the accelerator tube, can be used to generate short-pulse XFELs. Since the energy chirp produced by this phenomenon is such that the energy of electrons in the rear of the bunch is lower than at the front, compression requires a magnetic chicane with a positive R56, which shortens the path of the lower energy electrons. On the other hand, a normal simple electromagnetic chicane would have a negative R56, not applicable to this bunch compression. In this presentation, we report on the idea of a compact R56-positive magnetic chicane that can be inserted in a straight section and the results of its design study.

Speaker: Hitoshi Tanaka (RIKEN SPring-8 Center)

16:00 An alternative lattice for the ZIPS storage ring

Since synchrotron radiation sources have many advanced characteristics such as high radiation power, high brightness, broad spectral range, transverse coherence, and excellent time structure, they have become powerful tools for exploring microscopic material structures. With the growing demand for industrial researches, several dedicated industrial light sources are under operation or construction around the world. Zhejiang Industrial Photon Source (ZIPS) is designed to provide a scientific platform for industrial applications within the X-ray region in China. As a preliminary design, the ZIPS storage ring adopts a modified Triple-Bend Achromat (TBA) lattice with an energy of 2.6 GeV and a low emittance of 3.88 nm · rad. Details of the lattice design are presented in this paper.

Speaker: Mr Lei Guo (Hiroshima University)

16:00 An IGBT pulser for the nonlinear in-vacuum kicker at Taiwan Photon Source

A test unit pulser for the proposed NIK (nonlinear in-vacuum kicker) project at TPS (Taiwan Photon Source) was fabricated in order to provide uniform kick strength applying onto the injected bunch train. This newly built flattop pulser gives much improved drive current pulse shape in comparison with previously used half-sine pulser. This flattop pulser will result in high injection efficiency and provide adjustable capability in terms of bunch train filling pattern.

Speaker: Mr Chyi-Shyan Fann (National Synchrotron Radiation Research Center)

16:00 Analytical model for the transition to superradiance in seeded free-electron lasers

Free-electron lasers (FEL) seeded by short radiation pulses can exhibit superradiant behavior. In the superradiant regime, the pulse simultaneously compresses and amplifies as it propagates through the FEL, making superradiance very promising for pushing the performance limits of attosecond x-ray FELs. To date, this regime has been studied in asymptotic limits, but there is no model for how the initially linear dynamics of the seeded FEL transition into the nonlinear superradiant behavior. We derive an analytical model for the 1D FEL seeded by a short pulse which accurately captures the linear dynamics, the nonlinear superradiant evolution, and the smooth transition between them. Our model fills a critical gap in our understanding of FEL superradiance and nonlinear time-dependent FEL physics more broadly, and may provide a bridge to the corresponding problem in three-dimensions, and analogous problems in other fields exhibiting soliton behavior.

Speaker: River Robles (Stanford University)

16:00 Application of fast algorithms to calculate dynamic and momentum aperture to the design of ALBA II

In synchrotron light sources, the non-linear magnetic fields and Touschek scattering limit the stability of electron motion, determining the dynamic aperture (DA) and the momentum acceptance (MA). Optimizing both the DA and the MA is crucial to maximize injection efficiency and the beam's lifetime, but it is numerically expensive. We implement recently developed algorithms that speed-up their calculation in CPUs: Flood Fill and Fast Touschek Tracking (FTT). Applying these to the analysis of the ALBA II lattice and comparing them to the existing methods, we obtain rigorous and faster results using Flood Fill, and ones with a slight loss of accuracy for FTT.

Speaker: Thomas Günzel (ALBA Synchrotron (Spain))

16:00 Averaged FEL algorithm to simulate an arbitrary FEL polarization

FEL simulation codes are essential tools for simulating various FEL scenarios. Among the algorithms, the orbit-averaged algorithm is the most widely used due to its speed and low computational cost. The averaged algorithm simplifies physics model, so present codes such as GENESIS and SIMPLEX have limitations to model accurate features like FEL polarization and variations in electron beam current. Such details are possible when using an unaveraged algorithm (like PUFFIN). In this presentation we introduce an approach based on the averaged algorithm to simulate arbitrary FEL polarization and non-fixed electron beam current. Our method involves initializing all particles at the beginning of the simulation and performing particle calculations at each simulation step to account for the non-fixed electron beam. Additionally, arbitrary FEL polarization is calculated by modifying the FEL equations using the elliptical undulator formula and the GENESIS algorithm. Finally some demonstration will be shown comparing the performance of PAL-XFEL and results from other simulation codes to highlight the capabilities of this approach.

Speaker: MyungHoon Cho (Pohang Accelerator Laboratory)

16:00 Bayesian optimization for generating attosecond X-ray FEL pulses

Ångström and attosecond represent fundamental spatiotemporal scales for studying electron dynamics in various materials. Recently, high-power attosecond hard X-ray pulses have been successfully demonstrated at the European XFEL using the self-chirping operation mode. However, the current process heavily depends on manual tuning by experienced operators, which is time-intensive and less scalable. In this work, we report recent advancements in automating and optimizing the generation of high-power attosecond X-ray pulses using Bayesian optimization techniques. By leveraging machine-learning-based approach, we aim to enhance pulse energy, spectral quality, and operational efficiency, paving the way for more accessible and reproducible attosecond X-ray experiments.

Speaker: Chenzhi Xu (Shanghai Institute of Applied Physics)

16:00 Bayesian optimization for the local bump injection in the HLS-II storage ring

Currently, a conventional local bump injection system with four pulsed dipole kicker magnets is adopted in the Hefei Light Source II (HLS-II) storage ring to achieve topoff operation. Due to the multipole magnets located between the kickers in the injection section, the local bump injection presents technical challenges in forming a perfect closed
bump, which causes oscillation to the stored beam. In order to reduce the injection disturbance on the stored beam, the Bayesian Optimization (BO) method is employed to determine the kick angles of the four bump kickers.

Speaker: Mr Lei Guo (Hiroshima University)

16:00 Beam dynamics studies and vacuum diagnostics in the Solaris storage ring

Since 2015, the National Synchrotron Radiation Center SOLARIS has operated a light source supporting eight experimental beamlines. Following vacuum chamber replacements and beamline upgrades, the total beam lifetime at 400 mA has reached 13 hours in decay mode operation. Regular lifetime measurements are conducted to monitor vacuum quality, residual gas composition, and potential stability issues arising from machine aging. Beam dynamics studies involve measuring electron beam lifetimes at 400 mA, 300 mA, and low currents (as low as 10 mA) under both multibunch and single-bunch operating modes. A particular focus is placed on intra-beam electron interactions influencing the Touschek lifetime and the effects of residual gas on beam scattering. These investigations provide valuable insights into vacuum performance, electron bunch behavior, and overall storage ring dynamics.

Speaker: Jacek Biernat (SOLARIS National Synchrotron Radiation Centre)

16:00 Canting schemes design for Korea-4GSR storage ring

In Korea-4GSR, a beamline utilizing a canted ID is planned to be built. The impact of the electron beam resulting from the canting structure were investigated, and design modifications were implemented to minimize these effects. Simulation results show that the impact on the beam is negligible.

Speaker: Gyeongsu Jang (Pohang University of Science and Technology)

16:00 Characterisation of beam dynamics sensitivity to misalignments in the PERLE injector

High current linear accelerators require the precise alignment of accelerating cavities to maintain a high beam quality. The PERLE (Powerful Energy Recovery Linac for Experiments) injector cryomodule is composed of four single-cell cavities, each of which can be independently tuned to allow greater control of the beam at this crucial point. Misalignments can lead to perturbations in the beam trajectory and contribute to an increased emittance and energy spread. Here we present a characterisation of the beam dynamics when various misalignments are applied in the injector. Various misalignments are applied, three in the translation axis (x, y, z), and two rotationally, yaw and pitch (𝚽, 𝚹). A study was conducted to determine the tolerances required misalignments to ensure an acceptable beam quality is maintained at. The results indicate that particular combinations of rotational and translational misalignments are especially detrimental to emittance. These findings provide an important guide for the subsequent design of the booster linac and alignment procedure.

Speaker: Connor Monaghan (University of Liverpool)

16:00 Coherent undulator radiation with account of the beam energy spread

When a microbunched beam is sent to a resonantly tuned undulator it radiates coherent radiation with the intensity propotional to the bunching squared of the beam. According to *, the radiated energy increases with the undulator length. This conclusion, however, is only valid if one ignores the energy spread of the beam (and also the beam angular spread). The finite energy spread smears the microbunching, ultimately suppressing coherent radiation beyond a certain distance. In this work, we calculate the radiation of a microbunced beam with an energy spread and find the maximum energy that it can radiate coherently.

Speaker: Gennady Stupakov (xLight Incorporated)

16:00 Combining SASE and external seeding at high repetition rate: FLASH upgrade status

The FLASH facility generates XUV and soft X-ray radiation in two FEL beamlines based on SASE and powered simultaneously by a single superconducting linac. To enable next generation user experiments a series of upgrades is coordinated within the FLASH2020+ project. Upgrades on the linac have been performed in a preparatory 9 month shutdown in 2021/2022 and have demonstrated to deliver an improved electron beam quality and parameter range for operation. Right now the upgrades are targeted towards the FLASH1 FEL beamline and will transit the FEL from SASE to external seeding at MHz repetition rate with near transform limited pulses at superb stability. With an APPLE3 design, the radiators will enable full polarisation control which, together with a THz radiator, new pump-probe lasers and the corresponding beamlines, will enable new experiments on e.g. circular dichroism of magnetic materials, chirality and resonant excitations. In this contribution, we report on the FLASH2020+ incorporated existing and upcoming alterations to the FLASH facility as well as to project progress with respect to the current as well as following near- and midterm installations.

Speakers: Lucas Schaper (Deutsches Elektronen-Synchrotron DESY), Mathias Vogt (Deutsches Elektronen-Synchrotron DESY)

16:00 Commissioning of the soft X-ray variable polarization afterburner at the European XFEL

Following the successful commissioning of the soft X-ray planar undulator system (SASE3), the European XFEL user community expressed a strong demand to extend the radiation properties and provide the possibility to obtain variable polarization modes. It was therefore decided to build a helical afterburner behind the SASE3 system in collaboration with Paul Scherrer Institute (PSI). The final installation of the undulators in the tunnel took place at the beginning of 2024. Since then, a series of measures have been taken to commission four APPLE-X undulators, which form the base for the helical afterburner. The main objective is to maximally suppress the linear polarization of planar undulators in order to obtain the purest radiation from helical undulators. The methods and results of the optimization to achieve a maximum contrast between the pulse intensity generated by planar and helical undulators as well as the operating experience are presented.

Speaker: Suren Karabekyan (European X-Ray Free-Electron Laser)

16:00 Compensation of an elliptically polarizing undulator in the HLS-II storage ring

The insertion devices (IDs) can severely affect the beam dynamics of a storage ring. Recently, a new elliptically polarizing undulator(EPU) is installed in the Hefei Light Source II (HLS-II) storage ring. The effects of this EPU can be modeled using the kick map method. In this paper, we present the kick map of the EPU with vertical mode and how it affects the beam dynamics. Since the HLS-II storage ring is compact, only four quadrupoles in the same straight section can be used to compensated the ID effect. The compensation result is also reported in this paper.

Speaker: Zachary Liptak (Hiroshima University)

16:00 Concept and preliminary design of the DALI accelerator lattice

The Dresden Advanced Light Infrastructure (DALI) project at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) is a visionary initiative to establish a state-of-the-art light source facility, catering to cutting-edge research in materials science, biology, and other interdisciplinary fields. A cornerstone of this ambitious project is the development of an advanced accelerator lattice tailored to meet the unique demands of high-intensity, ultra-bright photon production.
This presentation introduces the conceptual framework and preliminary design of the DALI accelerator lattice. Key features include a modular design optimized for stability, flexibility, and scalability, ensuring compatibility with diverse experimental setups. The lattice must integrate advanced beam dynamics solutions to achieve precise control over beam quality, energy spread, and emittance, crucial for generating high-brightness radiation.
Early design studies highlight the potential of DALI to set new benchmarks in light source performance. This presentation seeks to engage the accelerator community in refining the lattice design and exploring its applications in cutting-edge research.

Speaker: Najmeh Mirian (Helmholtz-Zentrum Dresden-Rossendorf)

16:00 Conclusions from the UK XFEL conceptual design and options analysis study

UK XFEL is a multi-stage project to pursue ‘next-generation’ XFEL capabilities, either through developing a new facility in the UK or by investing at existing machines. The project’s Science Case envisages a step-change increase in the number of simultaneous experiments, with transform-limited (‘laser-like’) x-rays across a wide range of pulse durations and photon energies (up to ~20 keV) being delivered together with an array of synchronised sources, at high repetition rate to approximately ten FELs (evenly spaced pulses at approximately 100 kHz per experiment, with flexibility). A subset of applications require increased pulse energy and higher photon energies at low repetition rate or in short bursts. The project is now in the final year of its three-year conceptual design and options analysis phase, in which it has produced a conceptual design to efficiently meet these requirements, as well as conducting an analysis of the costs, socio-economic factors, and sustainability of the different investment options. The conclusions of this study are expected to be of general interest to the community.

16:00 CW SRF gun generating beam parameters sufficient for CW hard-X-ray FEL

SRF CW accelerator constructed for Coherent electron Cooling project at Brookhaven National Laboratory frequently demonstrated record parameters using 1.5 nC 350 psec long electron bunches, typically compressed to FWHM of 30 psec using ballistic compression. In this paper we report experimental demonstration of CW electron beam with parameters fully satisfying all requirements for hard-X-ray FEL and significantly exceeding those demonstrated by APEX LCLS II electron gun. The most remarkable part of this achievement in this experiment that we used 10-years old SRF gun with modest accelerating gradient ~ 15 MV/m, a bunching cavity followed by basilic compression to generate 50 pC, 15 psec electron bunches with normalized emittance of 0.15 mm mrad and normalized project emittance of 0.2 mm mrad. In other words, we are presenting alternative method of generating CW electron beams needed for hard-X-ray FELs using existing and proven accelerator technology. We present description of the accelerator system setting, details of projected and slice emittance measurements as well as relevant beam dynamics simulations.

Speaker: Vladimir Litvinenko (Stony Brook University)

16:00 Design of a microbunched electron cooler energy recovery linac

Microbunched electron Cooling (MBEC) is a type of Coherent electron Cooling (CeC), suitable for cooling high energy protons; such an electron cooler can be driven by an energy recovery linac (ERL). The beam parameters of this design are based on cooling 275 and 100 GeV protons at the Electron-Ion Collider (EIC), requiring 150 and 55 MeV electrons, respectively. If implemented, a high energy cooler would serve to increase the average luminosity of the collider by mitigating the emittance growth due to degradation caused by various processes. This ERL is designed to deliver a bunch charge of 1 nC, an average current of 100 mA, and strict requirements on the transverse emittance, slice energy spread, and longitudinal distribution profile. This paper covers the current state of the design.

Speaker: Kirsten Deitrick (Thomas Jefferson National Accelerator Facility)

16:00 Design of beam spreader system at S3FEL

Shenzhen Superconducting Soft X-Ray Free Electron Laser (S3FEL) is a high-repetition-rate and high-brightness soft X-ray facility under construction. It is designed to support multiple user experiments simultaneously, each requiring different undulator lines and FEL parameters. This capability is made possible by the beam spreader system, which plays a pivotal role in transporting the electron beam from the exit of the LINAC to multiple undulator lines, predominantly facilitated by the Kicker-Septum system. The system eliminates transverse dispersion, coherent synchrotron radiation, and adopts an isochronous design, all critical for preserving beam quality. This paper outlines the basic layout and lattice design of the beam spreader, presenting the corresponding simulation results.

Speaker: Jitao Sun (Dalian Institute of Chemical Physics)

16:00 Design of beam transport system integrating active plasma lens for laser-plasma-driven EUV free-electron lasers

Laser-plasma accelerators (LPAs) produce high-quality electron beams with the GeV-level of the energy, the high peak currents and low emittance, making them ideal for compact novel free-electron lasers (FELs). However, the large angular divergence and energy spread of these beams pose challenges for efficient beam transport and overall FEL performance. This study explores the use of an active plasma lens (APL) as a capture block to improve the transport of LPA-generated beams into an undulator. Initial beam parameters were based on published results from LWFA studies. In this report, we present the results of the modeling conducted to design an efficient LPA-based electron beamline and optimize the FEL regime for the extreme ultraviolet (EUV) range. Our goal is to achieve saturation of the photon beam power within a single unit. The results show that the APL enables efficient beam transport and facilitates the generation of high-brightness coherent X-rays. This work underscores the potential of APLs in developing compact FELs and advancing LPA beams. This technology is essential for creating a new generation of FELs at ELI-ERIC in the Czech Republic and within the EuPRAXIA project.

Speaker: Mihail Miceski (Extreme Light Infrastructure Beamlines)

16:00 Design of bellows in HALF vacuum system

The fourth generation HALF light source is a kind of storage ring light source based on diffraction limit. On the one hand, the shielded bellows in the vacuum system is used to compensate the thermal expansion and cold contraction of the vacuum chamber, and to adjust the longitudinal and transverse offset of the vacuum chamber according to the requirements of installation and collimation, on the other hand, it provides continuous shielding in the adjacent vacuum chamber to reduce the impedance of the beam pipe. The shielded bellows consists of a shielding finger, a contact finger and an inner tube, the contact finger acts on the inner tube, and the contact force comes from the elastic force formed by pressing the spring finger on the contact finger. In the structure, the high temperature area of the shielding finger is separated from the high stress area, so as to improve the durability of the bellows. The main mechanical parameters are as follows: longitudinal compression: ≥ 8mm; stretching: ≥ 8mm; lateral offset: ≥ 1mm; overall permeability ≤ 1.02 after welding, so that it can meet the requirements of vacuum system.

Speaker: gangqiang ma (University of Science and Technology of China)

16:00 Design of RF system for 4th generation storage ring at Korea

A new 4th Generation Storage Ring (4GSR) will be constructed in Ochang, South Korea, by the end of 2029. A technical design review for the Korea 4GSR was completed at the end of 2023. The storage ring has a circumference of 799 meters and is designed for a maximum current of 400 mA at 4 GeV electron beam energy. The target emittance is below 100 pm-rad, with a calculated emittance of 62 pm-rad—100 times smaller than that of PLS-II, a 3rd-generation storage ring in Korea. The RF system for the Korea 4GSR comprises 10 normal-conducting cavities, a low-level RF (LLRF) system, a high-power RF (HPRF) system, and additional components. To ensure beam stability, Higher Order Mode (HOM)-damped cavities have been implemented. Additionally, we plan to install harmonic cavities to improve beam lifetime and reduce wakefields. For the LLRF system, we aim to apply a new digital feedback control scheme and implement FPGA chips. For the HPRF system, we have chosen to use a solid-state RF power amplifier (SSPA). This presentation highlights the design results of the RF system for the Korea 4GSR, as well as prototypes of the 3rd harmonic cavity and SSPA.

Speaker: Dr Bong Hyuk Choi (Korea Basic Science Institute)

16:00 Development of regenerative-amplifier FEL at the compact ERL

The compact ERL has been built in 2013 at High Energy Accelerator Research Organization (KEK) to a test machine of an energy recovery linac. Afterwards, two undulators have been installed in the compact ERL and a first light amplification (free-electron laser: FEL) in mid-infrared range has been observed in 2021. However, the intensity of light has not been achieved to the intensity saturation because of not enough undulator length. Since we are considering for industrial applications using it, the intensity has to be improved. There are several methods to improve the intensity, and we have decided to try a “regenerative-amplifier (RA) FEL” scheme and now it is under the construction. In this presentation, we will report the status and plan of RA-FEL development using the compact ERL.

Speaker: Takanori Tanikawa (High Energy Accelerator Research Organization)

16:00 Echo-enabled harmonic generation at the DELTA storage ring

Echo-enabled harmonic generation (EEHG) has been proposed as a seeding method for free-electron lasers but can also be employed to generate ultrashort radiation pulses at electron storage rings. With a twofold laser-electron interaction in two undulators ("modulators"), each followed by a magnetic chicane, an electron phase space structure with high harmonic content is produced, which gives rise to coherent emission of radiation at short wavelengths. The duration of the coherently emitted pulses in a third undulator ("radiator") is given by the laser pulse durations. Thus, EEHG pulses can be three orders of magnitude shorter but still more intense than conventional synchrotron light pulses. The worldwide first storage ring implementation of EEHG was undertaken at the 1.5-GeV synchrotron light source DELTA at TU Dortmund University by reconfiguring an electromagnetic undulator. With a total length of only 4.75 m, the setup is very compact and fits in a single straight section. The paper presents technical aspects of the EEHG implementation as well as first results.

Speaker: Shaukat Khan (TU Dortmund University)

16:00 Electron beam and laser-Compton X-ray parameters stabilization simulation study at KEK Laser-Undulator Compact X-ray facility

Electron beam and laser-Compton X-ray parameters stabilization simulation study at KEK Laser-Undulator Compact X-ray facilityis a normal conductivity multi-bunch electron linear accelerator devoted to develop an intense monochromatic source of laser-Compton X-ray for tomography applications.
The electron beam parameters absolute values and its stability were simulated at the ASTRA tracking code, while laser-Compton X-ray beam stability was simulated at CAIN. In reverse, this stability values allows to define the accelerating field stability requirements for the linear accelerator based laser- Compton X-ray sources.
This report demonstrates the electron beam parameters and laser-Compton X-ray stability simulation results. Also, the accelerating field stability requirements are discussed in this report.

Speaker: Prof. Konstantin Popov (High Energy Accelerator Research Organization)

16:00 Enhanced self-seeding - first experiments

Enhanced self-seeding (proposed in Phys. Rev. Lett. 125, 044801, 2020) is a concept for more stable, laser-like XFEL operation. The principle of enhanced self-seeding lies in strong lasing on the current spike in the SASE section, and picking the seed pulse with the flat, lower current portion of the beam. Recently, we performed experimental studies of this scheme with the existing hard x-ray self-seeding (HXRSS) at LCLS. We report on our findings and possible new self-seeding schemes.

Speaker: Aliaksei Halavanau (SLAC National Accelerator Laboratory)

16:00 Evaluation of coating thickness and thermal deposited power for nonlinear in-vacuum kicker

This paper presents a comprehensive evaluation of the relationship between titanium coating thickness and thermal deposited power in the ceramic chambers of the Nonlinear In-vacuum Kicker (NIK) system, a critical component in synchrotron light sources. The study focuses on optimizing the coating thickness to minimize magnetic field attenuation and thermal load, thereby enhancing the performance of the NIK system. Through simulation analysis, we demonstrate that a titanium coating thickness of 5 μm provides an optimal balance between magnetic field attenuation and thermal load management. Additionally, the uniformity of the coating layer is found to significantly impact the system's stability and efficiency. The findings offer valuable insights for the design and operation of NIK systems in synchrotron facilities, particularly for the Taiwan Photon Source (TPS).

Speaker: Chin-Chun Chang (National Synchrotron Radiation Research Center)

16:00 Experimental study on soft X-ray generation via Inverse Compton Scattering at CERN

This study explores the feasibility of using Compton Backscattering (CBS) as a compact source for generating photons in the extreme ultraviolet (EUV) to soft X-ray range, with potential applications in biological imaging and modern lithography. A CBS experiment was conducted at the AWAKE Run 2c test injector (ARTI), where electron bunches, accelerated up to 6 MeV by a high-gradient, brazing-free S-band photogun were collided with 1030 nm infrared pulses from the PHAROS femtosecond laser. The electron and laser beamlines were optimised for maximum CBS photon flux.

Speaker: Vlad Musat (European Organization for Nuclear Research)

16:00 Exploratory tests for the design of a Python accelerator middle layer

Several laboratories and facilities recently started joined efforts towards the realization of a python accelerator middle layer (pyAML) for control, tuning and optimization. This software is intended as a successor to matlab middle layer (MML), inheriting its features but also expanding to new ones (e.g., nonlinear optics and machine learning tools). Presently, several codes are available that provide some of the desired features. These codes have been adapted and tested at several of the participating laboratories to give input to the design of the pyAML. The most relevant features and results have been analyzed and are presented here together with the implications for the pyAML design.

Speaker: Waheedullah Sulaiman Khail (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 Exploring lattice candidates for TPS upgrade

The design of lattice candidates for the Taiwan Photon Source (TPS) upgrade is under investigation, focusing on Multi-Bend Achromat (MBA) and Hybrid Multi-Bend Achromat (HMBA) configurations. A 5BA lattice, which offers relaxed hardware requirements, can achieve a natural beam emittance in the hundred pm-rad range for a 3 GeV storage ring. The 6BA configuration shows promise in achieving phase cancellation without the need for harmonic sextupoles but presents challenges due to limited available space. The HMBA scheme is attractive for its simpler configuration and reduced reliance on nonlinear magnets. Preliminary results highlight the characteristics and trade-offs of each configuration, providing guidance for the future TPS upgrade.

Speaker: Dr Nuan-Ya Huang (National Synchrotron Radiation Research Center)

16:00 Exploring second harmonic generation in hard X-ray self-seeding FEL

Recently, the Hard X-ray Self-Seeding (HXRSS) setup at the European XFEL has been successfully demonstrated, achieving routinely pulse energies in the seeded signal of several hundreds of microjoules at various wavelengths. However, the shorter wavelengths pose a challenge to the impulse response of crystal, limiting output radiation and spectral performance. To address these challenges, a strategy combining HXRSS with second harmonic generation and tapering has been proposed. We have condcuted the Start-to-end simulations at 15keV and compared the output of the pulses with direct seeding at fundamental harmonic and seeding combined with 2nd harmonic. Tapering further improves energy conversion efficiency, leading to increased pulse energy and enhanced signal to noise ratio.

Speaker: Lu Cao (Deutsches Elektronen-Synchrotron DESY)

16:00 FEL performance enhancement with phase shifters at Dalian Coherent Light Source

A phase shifter collocated with an undulator is an efficient method to enhance the lasing performance of free-electron laser (FEL), particularly for seeded FEL. Dalian Coherent Light Source (DCLS) is a seeded FEL facility operating in high-gain harmonic generation (HGHG) mode to produce fully coherent vacuum ultraviolet laser. To achieve high FEL lasing performance, five phase shifters are interspersed among six undulators to match the phase of the electron beam and the FEL radiation field. This paper presents the commissioning results of these five phase shifters, with a primary focus on their impact on FEL lasing performance.

Speaker: Xinmeng Li (Dalian Institute of Chemical Physics)

16:00 Flash status 2024 - FEL operation for users and upgrade shutdown

FLASH, the XUV and soft X-ray free-electron laser at DESY, is currently undergoing the 2nd of two long upgrade shutdowns within the FLASH2020+ project. The 1st half of 2024 was dedicated to user operation. The upgrade shutdown started in June 2024, and we plan to come back to beam operation in August 2025.
Here we will discuss the operational highlights of the first half of 2024,
briefly describe the new features being implemented, and report on the
shutdown status.

Speaker: Mathias Vogt (Deutsches Elektronen-Synchrotron DESY)

16:00 Flat beam generation in photoinjectors for high brightness electron beams

The Energy Recovery Linac (ERL) combines the high repetition frequency of synchrotron radiation with the high brightness of FELs, showing great potential. Despite recent breakthroughs, the electron beam quality still fails to meet the requirements for driving short-wavelength FELs.
The method combining ERL with Angular Dispersion-induced Microbunching (ADM), proposed by the Shanghai Light Source team, to generate a fully coherent light source with GHz repetition frequency and MeV-level energy resolution, supporting multiple users. In this scheme, microbunching is generated by ADM, and its radiation intensity is limited by the vertical emittance of the electron beam. To enhance brightness, flat beam technology is employed to reduce vertical emittance and increase horizontal emittance through lateral emittance exchange, also aiding control of the ERL bending section emittance. The round-to-flat beam conversion significantly reduces vertical emittance. This study focuses on flat beam theory, lattice design, and optimization.

Speaker: Chaochao Xing (Shanghai Zhangjiang Laboratory)

16:00 Free electron laser optical axis measurement system

The polarization of the gamma-ray beam plays a critical role in experimental photonuclear research by probing angular momentum. For example, the multipolarities of the 80Se(g,n)79Se reaction can be assigned by measuring cross-sections relative to the plane of polarization. Dynamic control over gamma beam polarization will open new opportunities in nuclear research, particularly by allowing relative asymmetries to be calculated without the uncertainty introduced by relative detector efficiency. A gamma-ray beam with rotational linear poarization and high polarization purity (Plin ~ .99) has been demonstrated at the High Intensity Gamma-ray Source (HIGS)*. Without active tuning by an accelerator physicist, polarization quality is degraded due to decoupling of the free-electron laser (FEL) axis and the electron beam orbit. The FOAMS is an active feedback system that is sensitive to the small centroid motions of the FEL optical axis. Measurement uncertainty characterization has been conducted. Ongoing work will utilize this feedback system to automatically sustain controllable gamma-ray polarization for nuclear physics experiments.

Speaker: Stephen Yates (Triangle Universities Nuclear Laboratory)

16:00 Generation of short current spikes by laser modulation at FLASH

Generating few- or sub-femtosecond radiation pulses in a free-electron laser (FEL) requires precise control of the longitudinal phase space density of the driving electron bunch, as the FEL process depends strongly on the bunch current and energy spread profile. In an experiment conducted at FLASH in Hamburg, Germany, an energy modulation with linearly changing amplitude is imprinted onto part of the bunch by a laser pulse in an undulator upstream of the first bunch compression chicane. In subsequent longitudinally dispersive sections, a short current spike is created, as the linearly modulated region is compressed more strongly than the rest of the bunch. Measurements with a transverse-deflecting X-band cavity verify the creation of a short current spike, whose duration falls below the temporal resolution of the measurement setup of approximately 7 fs.

Speaker: Philipp Amstutz (TU Dortmund University)

16:00 Higher order mode assessment in a single mode accelerating cavity

With the upgrade from PETRA III to PETRA IV the requirements concerning the beam parameters increase. Thus, a special focus is placed on the suppression of higher order modes (HOMs) in the accelerating systems.
An Investigation of the already presented single mode structure showed the emergence of certain higher order modes. These cavity eigenmodes are now examined by evaluating and assessing their degrading influence on the particle beam by calculating kick and loss factors. Subsequently, the cavity geometry is changed to attenuate the HOMs’ influences or even supress them entirely. In this paper the optimization process using numerical simulations together with the achieved results and cavity structure are presented.

Speaker: Leon Kronshorst (Technical University of Darmstadt)

16:00 Improvements in FLASH operation through the use of the laser heater

FLASH is an XUV and soft X-ray free-electron laser (FEL) facility that comprises a superconducting linear accelerator with a beam energy of up to 1.35 GeV which drives two FEL beamlines in parallel and the plasma wakefield accelerator experiment FLASHForward. Within the upgrade program FLASH2020+, a laser heater was installed upstream of the first bunch compression chicane to mitigate microbunching instability in the linear accelerator by a controlled increase of the uncorrelated energy spread. The effect of the laser heater on microbunching instability and final energy spread has been verified with a transverse deflecting structure. In this paper, we describe the layout of the laser heater and report on improved operational aspects. It has been shown that the laser heater eliminates coherent contributions to visible transition radiation in transverse beam size measurements and, thus, contributes to better electron beam matching. In addition, an increase in the FEL output power is demonstrated, especially for first operation of the 3rd harmonic afterburner with variable polarisation.

Speaker: Philipp Amstutz (TU Dortmund University)

16:00 Interference of harmonics observed in a free-electron laser oscillator

In an FEL oscillator with a planar undulator, odd harmonics appear as either spontaneous emission or as linear and nonlinear harmonics associated with the FEL pulse evolution. Additionally, misalignment of the electron beam or the resonator can lead to off-axis gain, generating even harmonics. We conducted an experiment at KU-FEL, operated at 5 µm, to measure the 6th- and 7th-harmonic spectra using a spectrometer equipped with an intensified CCD. Scanning the gate timing enabled us to capture the time evolution of the harmonic spectrum within the macro pulse. The results revealed that the harmonic spectra broaden as the macropulse intensity rises, with interference observed between the harmonics. Such interference between adjacent-order harmonics has also been observed in high-harmonic generation from solid-state targets and utilized to measure the carrier-envelope phase (CEP) of optical pulses. Based on the results of our FEL harmonic measurements and numerical simulations, we will discuss the potential for CEP measurement using FEL harmonics, highlighting the implications for further developments in FEL-based attosecond X-ray sources via high-harmonic generation.

Speaker: Ryoichi Hajima (National Institutes for Quantum Science and Technology)

16:00 Investigation of new collimator head material candidates for SuperKEKB and future collider

Currently, SuperKEKB faces the challenge of sudden beam loss (SBL), which occurs with almost no prior sign. The causes of SBL are not fully understood. A damaged collimator reduces its ability to suppress beam background noise compared to an undamaged one. In cases that the beam background noise reduction decrease, it is necessary to stop the operation and replace the collimator jaw. Therefore, a robust collimator head material is required. In this conference, we report the results of our investigation of copper-carbide graphite (CuGr), which is a candidate as a new collimator head material for SuperKEKB. Measurements of electrical conductivity in the high-frequency region, secondary electron yield, outgassing rate due to photon stimulated desorption, and the amount of dust generated by ultrasonic cleaning of CuGr, along with simulation results of beam background with CuGr, are presented.

Speaker: Shinji Terui (High Energy Accelerator Research Organization)

16:00 Isolated attosecond pulses generation with the microbunching synthesis

Attosecond x-ray pulses play a crucial role in the study of ultrafast phenomena involving inner and valence
electrons. Especially isolated attosecond pulses with high photon energy and high peak power are of great
significance in single-shot imaging in the soft x-ray region, life sciences, and attosecond pump-probe experiments. In modern accelerators, laser manipulation of electrons can be used to tailor the ultrafast properties of
free-electron laser pulses. In this paper, we propose a novel laser manipulation technique that makes use of two
many-cycle, obliquely incident laser beams with mutual delays to synthesize microbunching rotation on the scale
of infrared laser wavelengths within the electron bunch. This synthesis microbunching rotation ultimately leads to
an enhanced current contrast ratio between the main peak and the surrounding satellite peaks within the bunch.
By properly accounting for the longitudinal space-charge fields within the undulator, a tapered undulator can
further suppress the side peaks in the radiation pulse and enable the selection of an isolated, hundred-attosecond,
GW-level soft x-ray pulse.

Speaker: Dr Hao Sun (Institute of Advanced Science Facilities, Shenzhen)

16:00 Lattice design and optimization of the HALF storage ring with superbend

The HALF storage ring is a 2.2 GeV diffraction limited storage ring, with radiation photons mainly in the vacuum ultraviolet (VUV) to soft X-ray wavelength ranges. In order to meet the demand for high brightness hard X-rays, HALF plans to replace 0.9 T normally bending magnet with 6 T superbend. This paper reports two lattice design schemes, replacing one bend and two bends respectively. The beam dynamics effects of storage ring lattice with superbends has been also discussed.

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

16:00 Leveraging the capabilities of LCLS-II: linking adaptable photoinjector laser shaping to x-ray diagnostics through start-to-end simulation

SLAC’s LCLS-II is advancing towards MHz repetition rate attosecond X-ray pulses, creating opportunities to optimize X-ray generation through machine-driven controls and diagnostics via start-to-end simulation. Advanced laser shaping and upconversion techniques at the photoinjector, such as spatial light modulator-based pre-amplifier pulse shaping linked to nonlinear methods such as dispersion-controlled nonlinear synthesis or four-wave mixing, enable precise electron bunch control at the source. Downstream, diagnostics like the Multi-Resolution COokiebox (MRCO)—a 16-channel time-of-flight spectrometer—characterize X-ray pulse profiles, providing real-time feedback on attosecond X-ray pulses or attosecond X-ray substructure. We present developments towards a framework linking programmable photoinjector laser shaping to X-ray diagnostics, enabling data-driven optimization of the X-ray source. This approach combines machine learning, high-throughput feedback, and advanced control to align LCLS-II capabilities with experimental goals, laying the foundation for optimization of attosecond-scale precision in X-ray experiments.

Speaker: Jack Hirschman (Stanford University)

16:00 Magnet crosstalk in highly-compact light-source storage ring

Electron storage rings based on multi-bend achromat (MBA) lattice can achieve very low natural emittances. Several fourth generation light sources have been built and operating, the natural emittances of which are a few 100 pm or even lower than 100 pm, providing high brightness photon beams to users. Since the lattice of MBA storage ring tends to be highly compact, the field of a magnet may be affected by the neighboring magnets. This effect turned out to be significant in the new Swiss Light Source storage ring with 7-BA lattice during its design study: the integral fields of magnets are altered by a few percent due to the magnet cross talk at locations, which is an order of magnitude larger than the field precision typically required. We present how we managed to reproduce the design magnetic fields and optics including the cross talk effects

Speaker: Ciro Calzolaio (Paul Scherrer Institute)

16:00 Maximizing the hard-X-ray performance of SwissFEL by systematic re-alignment and recalibration of the Aramis undulator line

Aramis, the hard-X-ray undulator line at the free-electron laser SwissFEL at the Paul Scherrer Institute, has been in user operation at full beam energy since the end of 2018. After steady improvements of the performance until 2022, it proved difficult to maintain the achieved performance level in recent years. Now, after a systematic re-alignment and recalibration of the undulator line and a subsequent optimization of all relevant machine parameters, we have reached a new record photon pulse energy of 1 mJ at 12 keV photon energy. This contribution describes the steps taken and lessons learned to achieve and maintain this high level of performance.

Speaker: Nicole Hiller (Paul Scherrer Institute)

16:00 Multi-dimensional phase space reconstruction based on neural network and polarizable transverse deflecting cavity

High-dimensional phase space reconstruction is an important tool for achieving precise beam simulation and optimization. We adopt a machine learning approach with a polarizable transverse deflecting cavity to reconstruct the multi-dimensional phase space of electron beam. By scanning the strength of the quadrupole magnets and the polarizations of the deflecting cavity, projections of the multi-dimensional phase space in different directions are obtained. A neural network is first trained with a large dataset, and the trained model is then applied to reconstruct the phase space. The result shows that the reconstructed phase space is good agreement with the original one. This report will describe the methods and results in detail.

Speaker: Jitao Sun (Dalian Institute of Chemical Physics)

16:00 Numerical simulation of on-axis helical undulator radiation using SCILAB-Xcos model

Abstract—A SCILAB Xcos model, developed using SCILAB software version 6.1.1, was implemented to simulate the on-axis radiation intensity of a helical undulator, (undulator parameter= 1, undulator wavelength 5cm, number of periods= 10, device length 0.6 m) with an electron beam (1, 2, & 3 GeV) and beam current as Ib = 3–6 × 10⁻⁶ Ampere. A numerical approach is utilized to perform the undulator radiation intensity calculations. The computed results were validated by comparing the on-axis undulator radiation intensity with those obtained from SPECTRA, an open-source synchrotron radiation (SR) calculation software.

Speaker: Ms Mahazbeen Sayed (Rajiv Gandi Proudyogiki Vishvidhyala)

16:00 Optimal beam energy for ultra low emittance storage rings

As new synchrotron light sources push for lower emittances, intra-beam scattering (IBS) becomes an increasingly more important factor in determining the final beam distribution properties. Because IBS depends strongly on beam energy, in the regime of ultra-low emittance rings, beam energy is a parameter to be optimized for best beam performance. In this report, we study the optimal beam energy for various lattices and its dependence on bunch lengthening and damping wigglers.

Speaker: Xiaobiao Huang (SLAC National Accelerator Laboratory)

16:00 Optimization of PLS-II

PLS-II has been faithfully fulfilling its role for 13 years since it launched its user service in 2012. As the 4GSR project is currently underway in South Korea, upgrading PLS-II to PLS-III is expected to take a significant amount of time. Therefore, how PLS-II can be optimized and used well over a significant time in the future is an important question. In this presentation, we present how to improve the performance of the linear accelerator and the storage ring for PLS-II optimization. First, in the PLS-II linear accelerator, we consider using a Sub-Harmonic Buncher to generate a single bunch electron beam. For beam injection, we consider introducing a Nonlinear Kicker instead of the 4-Kicker in use. In the storage ring, we propose to improve the speed of a Fast Orbit Feedback System, which is presently limited from 800 Hz to a few kHz.

Speaker: Changbum Kim (Pohang Accelerator Laboratory)

16:00 Optimization of the longitudinal phase space of the electron beam for generating attosecond soft X-ray pulses at PAL-XFEL

At the Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL), a scheme for generating attosecond XFEL pulses in the soft X-ray undulator line is under development using the Enhanced Self-Amplified Spontaneous Emission (E-SASE) method with an external laser pulse. To account for the slippage effect in the soft X-ray region, a mid-wavelength infrared (IR) laser pulse will be employed in the E-SASE section to create a sufficiently wide current spike. Following the E-SASE section, an additional wiggler will be used to introduce a strong energy chirp within the current spike via longitudinal space charge effects. This approach enables lasing exclusively within the current spike when applying strong reverse tapering in the undulator line, effectively suppressing background radiation. In this presentation, the optimization of the longitudinal phase space of the electron beam will be discussed by exploring the condition of the E-SASE section and wiggler for the attosecond soft X-ray pulses generation at PAL-XFEL.

Speaker: Chi Hyun Shim (Pohang Accelerator Laboratory)

16:00 Optimization of undulator tapering for the laser heater shaped electron bunch at PAL-XFEL

The pulse duration of the X-ray free-electron laser (XFEL) relies on the pulse duration of the electron bunch. The energy distribution of the electron bunch can be manipulated by using the laser heater in the purpose of generating attosecond pulse duration electron bunch current profile. Therefore, the resultant electron bunch current profile after the bunch compressor chicanes is programmable by the laser parameters. To obtain further bunch compression with the high current electron bunch profile, we investigate the hard X-ray beamline setup for the longitudinal space charge (LSC) field effect desired at the magnetic dogleg where is right before the hard X-ray undulator section. The hard X-ray undulator tapering is optimized for the linear energy chirp of the ultra-short electron bunch.

Speaker: Kookjin Moon (Pohang Accelerator Laboratory)

16:00 Optimizing Cherenkov waveguide seeding for THz SASE FELs towards stable, few-cycle pulses

The PITZ facility at DESY in Zeuthen has demonstrated the first operational high peak and average power THz self-amplified spontaneous emission (SASE) free electron laser (FEL). The current setup displays the onset of saturation at a central frequency of 3THz using a 3.5m long LCLS-I undulator. However, the THz user community has expressed the need for carrier-envelope phase (CEP) stability and the availability of few-cycle THz pulses to complement the currently demonstrated long pulses. In this work, simulations are conducted to evaluate and optimize FEL performance by incorporating a Cherenkov waveguide to seed the process. The waveguide parameter space is scanned to vary energy modulation depth and frequency, after which the performance is estimated using the space charge tracking algorithm, ASTRA, and the FEL simulation code, Genesis1.3. The optimized parameters allow saturation to be reached much earlier, while also significantly increasing the shot-to-shot stability. Down the line, the implementation of such a scheme would facilitate generation of few-cycle, CEP-stable THz pulses to be used in user experiments.

Speaker: Karel Peetermans (Deutsches Elektronen-Synchrotron DESY)

16:00 Orbit alignment study in the collimation section at the European XFEL

Orbit alignment plays an important role in free-electron laser (FEL) facilities, particularly in the collimation section, where multipoles are strategically positioned near the collimators as part of the specialized optics design. At the European XFEL, a strong dependence of lasing performance on the orbit in the collimation section has been observed. This study focuses on calibrating the central positions of the collimators using an orbit bump scanning technique combined with beam loss detection. Additionally, the influence of orbit alignment in the collimation section on lasing performance was systematically investigated, offering valuable insights into optimizing FEL operation.

Speakers: Bingyang Yan (Shanghai Institute of Applied Physics), Shan Liu (Deutsches Elektronen-Synchrotron DESY)

16:00 Plasma based optics for electron beam fast micro-bunching

The utilization of plasma devices in beam transport is slowly being accepted as a worthy alternative thanks to its potential in maintaining or even reducing particle beams emittance but also for its compactness which supplements the recent advances in compact laser plasma acceleration systems. However, their use can go beyond the substitution of magnets. In this work, the utilization of a low density plasma device to micro-bunch electron beams through a "cascade focusing" caused by the beam generated wake inside the plasma. In addition, specialized particle in cell tools to study such phenomena over long distance (>cm) taking advantage of relativistic reference frames is swiftly presented. Such devices present a great potential for shortening future FEL facilities and increasing the efficiency of current.

Speaker: Dr Driss Oumbarek Espinos (High Energy Accelerator Research Organization)

16:00 Preliminary beta beating correction at the Canadian Light Source

The Canadian Light Source does not currently correct beta beating driven by its insertions devices. However, it has been known for some time that insertion device correlated vertical beam size changes can cause large reduction in flux at the VESPERS beamline. In this work we discuss our preliminary explorations to control the vertical beam size and correct beta beating.

Speaker: Cameron Baribeau (Canadian Light Source (Canada))

16:00 Present status of Kyoto University free electron laser

Kyoto University Free Electron Laser (KU-FEL) has been developed for promoting energy related researches in Institute of Advanced Energy, Kyoto University. Currently two accelerator based infrared light sources, a mid-infrared FEL (MIR-FEL) and THz coherent undulator radiation (THz-CUR) are available. MIR-FEL covers the wavelength region from 3.4 to 26 micro-m and THz-CUR covers the frequency region from 0.1 to 0.45 THz. Present status and perspectives of those light sources will be presented in the conference.

Speaker: Heishun Zen (Kyoto University)

16:00 Progress in CBXFEL construction at SLAC

Cavity-based XFEL - CBXFEL - is an ongoing experiment at SLAC Accelerator National Laboratory. It utilizes first seven LCLS hard x-ray undulators, wrapped into a rectangular Bragg cavity. CBXFEL is expected to operate at 9.831 keV, and serve as a proof-of-principle device for future large scale cavity-based systems. We report on the recent status and preliminary experimental results.

Speaker: Aliaksei Halavanau (SLAC National Accelerator Laboratory)

16:00 Pulsed Compton gamma-ray beam generation using pulsed FEL beam

Gamma-ray induced nuclear physics experiments rely on good signal-to-noise ratio, requiring accurate rejection of detector background. One source of this background is the interaction of cosmic rays with nuclear detectors. The Duke High Intensity Gamma-ray Source (HIGS) is typically operated in quasi-CW mode, requiring background measurements to be conducted independently of data production runs. A pulsed mode of HIGS beam operation enables improved rejection counts by allowing time discrimination between detector counts in coincidence with the gamam beam and detector counts out of coincidence with the beam.

To achieve a HIGS beam with good pulse quality, a fast steering magnet has been used to decouple the FEL beam from the HIGS beam in the interaction region. By periodically overlapping the electron and FEL beams, gamma production can be limited to only the periods of overlap. Gating on these gamma pulses has been shown to reduce signal to noise ratio by at least 3 orders of magnitude.*,*,** However, this technique produces poor results at low energies, requiring development of more sophisticated gating techniques.

Speaker: Stephen Yates (Triangle Universities Nuclear Laboratory)

16:00 Realisation of a 1.5 GHz single mode cavity for PETRA IV

In the period from October 2021 to August 2024, a cavity was developed for the 3rd harmonic system of PETRA IV. The development has progressed so far that a complete CAD model already exists. The cavity design has been reviewed by an external expert and approved. The project team is now working on clarifying the final details of the design and preparing all the technical documentation for the production of the cavity. This article reports on the issues that need to be addressed in order to turn the simulation and CAD model into a real, fully functional cavity.

Speaker: Michael Bousonville (Deutsches Elektronen-Synchrotron DESY)

16:00 Realizing steady-state microbunching with Optical Stochastic Crystallization

Optical Stochastic Cooling (OSC) is a state-of-the-art beam cooling technology first demonstrated in 2021 at the IOTA storage ring at Fermilab's FAST facility. A second phase of the research program is planned to run in 2025 and will incorporate an optical amplifier to enable increased cooling rates and greater operational flexibility. In addition to beam cooling, an OSC system can be configured to enable advanced control over the phase space of the beam. An example operational mode could enable crystallization, where the particles in a bunch are locked into a self-reinforcing, regular microstructure at the OSC fundamental wavelength; we refer to this as Optical Stochastic Crystallization (OSX). OSX represents a new path toward Steady-State Microbunching (SSMB), which may enable light sources combining the high brightness of an FEL with the high repetition rate of a storage ring.  Such a source has applications from the terahertz to the extreme ultraviolet (EUV), including high-power EUV generation for semiconductor lithography. This contribution will discuss the development of OSX within the OSC program at IOTA, including the design of the experiment and simulations results.

Speaker: Michael Wallbank (Fermi National Accelerator Laboratory)

16:00 Recent status and plan of ERL test accelerator at KEK

The compact ERL (cERL) is a test accelerator operating at KEK. Its main purposes are to develop key technologies related to energy-recovery linacs and high-current superconducting accelerators for industrial applications. An important goal of our activity is to realize a high power FEL source for future EUV lithography.
In recent years, we have been working on demonstrating high current beam operation in energy-recovery mode. We will summarize the status of the facility and lessons learned in recent beam operations, and discuss our development plan for the future project.

Speaker: Yosuke Honda (High Energy Accelerator Research Organization)

16:00 Relativistic strophotron free electron laser

The scheme with quadrupole lenses is presented for realization relativistic strophotron type Free electron laser. Equations of motion are solved and trajectories are found. It is shown, that movement of electrons in presented scheme is stable in both transverse directions.

Speaker: Koryun Oganesyan (Institute of Experimental Physics of the Slovak Academy of Sciences)

16:00 Research plans for the University of Hawai’i Accelerator and Free-Electron Laser Lab

The accelerator and free-electron laser (FEL) laboratory at the University of Hawai’i at Manoa (UHM), established by John Madey, has been in standby since his passing in 2016, with operations further paused during the pandemic. Recent efforts aim to recommission the facility, which includes a thermionic gun, an S-band linear accelerator reaching 45 MeV, and a Mark III undulator FEL oscillator producing tunable infrared light. Previously, 3 μm infrared light from this undulator demonstrated the capability to generate 10 keV X-ray photons via inverse Compton scattering. Current upgrades include enhancements to vacuum systems and linac controls.
Future plans focus on enhancing cathode performance, developing 3D FEL simulations for superradiance studies, achieving phase coherence with interferometer optics, and using waveguides for THz generation. Recent GINGER simulations explored FEL oscillator output under varying Desynchronization conditions, demonstrating pulse train formation. The revived UHM accelerator will advance FEL science and train the next generation of researchers.

Speaker: Amir Weinberg (University of Hawaii System)

16:00 Simulation and optimization of a sub-THz Cherenkov FEL at AREAL

A circular waveguide lined with a thin dielectric layer enables electron bunches propagating within the structure to radiate light in the (sub-)THz regime. In this work, we perform simulations of low-energy electron beams traversing extended waveguides to analyze the dynamics of beam bunching and lasing within the structure. By exploring the free-electron laser (FEL) process in this context, we demonstrate the potential of waveguides as a cost-effective alternative to undulator-based FELs. The study employs a simulated model of the AREAL LINAC at the CANDLE SRI to demonstrate these effects and provide realistic results. The simulations are performed using the space charge tracking algorithm ASTRA and the wakefield solver ECHO. For optimization of the system, the genetic optimization algorithm GIOTTO is applied to refine both the waveguide and accelerator variables. Using a 4 MeV electron beam with a charge of 300 pC, the optimized setup achieves a radiation frequency of 100 GHz with energy outputs exceeding 20 µJ in a waveguide of only 1.2 meters length. These results underscore the feasibility of this method, offering a innovative pathway to produce intense THz radiation.

Speaker: Karel Peetermans (Deutsches Elektronen-Synchrotron DESY)

16:00 Simulation studies on optimization of hard and soft X-ray beamlines for parallel user service at the PAL-XFEL

PAL-XFEL (Pohang Accelerator Laboratory X-ray Free Electron Laser) is a facility that generates high-brightness FEL for users to perform the FEL-based sciences. Currently hard and soft X-ray (HX/SX) beamlines are operational, but the parallel operation can be done with less than 60 Hz using a single electron bunch from the electron injector. Therefore, for the user service with maximum repetition rate of 60 Hz on both HX and SX beamlines, a scheme that uses two bunches from the injector with an exact single cycle of 2.856 GHz frequency is under consideration. Particularly, simulation study is necessary to understand the optimal accelerator condition for both HX and SX since the SX shares the same accelerator condition up to the third accelerating column with the HX beamline. In this study, we show discussions using the particle tracking simulations showing the optimal conditions for both beamlines. We also present the potential issues to be considered in the actual operations such as error of RF cavity amplitude.

Speaker: Haeryong Yang (Pohang Accelerator Laboratory)

16:00 Simulation study on fast beam-based alignment for commissioning of light sources

Beam based alignment (BBA) plays an important role in the commissioning of the light sources. To speed up the BBA, a BBA method using AC excitation, called fast BBA (FBBA), has been proposed and is tested in several existing light sources. In the FBBA, the beam orbit is sinusoidally modulated at around 10Hz by AC correctors, and the change in the beam response when a target quadrupole magnet strength is changed is measured using fast beam position monitors (BPM) at about 10kHz. To apply FBBA to light source commissioning, a simulation study of FBBA using random variables as response functions was performed to calculate the optimal corrector strength and variation of the strength of a quadrupole as a function of the BPM noise. We also improved the FBBA and found that a new FBBA scheme using two AC correctors of different frequencies separated by 1/2π betatron phase for one plane (horizontal or vertical) can suppress the BPM offset error by up to 10.

Speaker: Masahito Hosaka (University of Science and Technology of China)

16:00 Single spike hard x-ray free-electron laser pulses generated by photocathode laser shaping

We report the generation of single spike hard x-ray pulses at the Linac Coherent Light Source enabled by temporal shaping of the photocathode laser. The pulses were produced with typical pulse energies of 10 uJ and full-width at half-maximum spectral bandwidths averaging 30 eV, corresponding to a 60 attosecond Fourier-limited pulse duration. These pulses open new doors in electronic-damage-free probing of ultrafast phenomena and, eventually, attosecond hard x-ray scattering experiments. We discuss future plans to characterize the pulse in the time domain using hard x-ray angular streaking and a hard x-ray split and delay device.

Speaker: River Robles (Stanford University)

16:00 SLS 2.0 storage ring upgrade overview

The Swiss Light Source, SLS, storage ring has been rebuilt as SLS2.0, to improve the radiation brightness by about two orders of magnitude. All components of the storage ring lattice and its supporting infrastructure are newly constructed and were installed during a 15-month shutdown that began in October 2023. The linac and booster synchrotron received only small modifications with the exception of a new power supply for the main magnet circuit with its 3 Hz current ramp.
The new 7 bend achromat arcs had to fit the existing tunnel footprint and the location of the beamline exit ports resulting in tiny distances between magnets. In addition, all bends (and reverse bends) are based on permanent magnets necessitating thorough cross-talk studies due to larger stray magnetic field. The high density of magnets prevented the installation of vacuum bellows required for in-situ bake-out, so the twelve vacuum arc strings, of 18 m in length each, were installed in the ring after activation and pumping to a pressure around 1.e-11 mbar. Four HOM damped RF cavities at 500 MHz are installed in a row and supplied by four solid-state amplifiers of 150kW each. Two beamlines are dedicated to beam diagnostics and newly developed BPM and feedback systems monitor and stabilize the beam. This paper describes the main challenges faced during the SLS storage ring upgrade and gives an overview of the presently achieved performance. Beam commissioning details are described in a companion paper.

Speaker: Romain Ganter (Paul Scherrer Institute)

16:00 SOLEIL II project: entrance in the construction phase

SOLEIL II is the French upgrade project to build the science of tomorrow with synchrotron light radiation. Providing the highest brilliance in its class while maintaining the radiation range from IR to hard X-rays, the project is an ambitious triple upgrade of the SOLEIL facility: accelerators (new booster and storage ring), 29 beamlines and 3 laboratories, and an information technology transformation plan. High Order Achromat based on multi-bend achromat lattices will be used to replace both the storage (SR) and booster rings of the Synchrotron SOLEIL. The achieved equilibrium emittance of the SR (below 100 pm.rad, 354 m, 2.75 GeV) is about 50 times smaller than that of the existing Storage Ring (4000 pm.rad). To ensure the technical feasibility, an intensive R&D phase based on extensive numerical simulations, prototyping and measurements has been carried out. This paper presents the latest status of the project, the updated timeline, and describes the main results obtained so far in terms of performance and the prototypes launched in many technical domains (lattice, magnets, insertion device, vacuum, alignment…).

Speaker: Mr Keihan Tavakoli (Synchrotron soleil)

16:00 SOLEIL synchrotron light source lastest news

The synchrotron SOLEIL is France's 2.75 GeV third-generation synchrotron light source and serves as a cutting-edge research laboratory dedicated to advanced experimental techniques for matter analysis at the atomic scale. It also functions as a service platform accessible to both scientific and industrial communities. This abstract highlights the performance of the accelerators, which deliver exceptionally stable photon beams to 29 beamlines. Key figures of merit from the past year are reported, along with a review of several incidents and the lessons learned to prevent recurrence. Additionally, major research and development efforts addressing component obsolescence are outlined. The status of the LINAC upgrade is also discussed, alongside plans to use SOLEIL's current accelerator as a test bench to validate and precommission critical equipment for the forthcoming SOLEIL upgrade.

Speaker: Mr Keihan Tavakoli (Synchrotron soleil)

16:00 Spatial polarization distribution measurements of gamma rays produced by inverse Compton scattering

Highly polarized MeV gamma rays, produced by Laser Compton Scattered (LCS) of a polarized laser with an electron beam, offer a unique probe for basic and applied physics research. As the polarization characteristics of these gamma rays vary with the position of the beam cross section, it is essential to understand the polarization properties when using polarized gamma rays * . However, detailed measurements of the two-dimensional spatial polarization distribution have not yet been conducted. In the UVSOR synchrotron facility, a polarimeter was developed to measure the spatial polarization distribution of linearly polarized gamma rays. The polarimeter is based on asymmetry measurements of the Compton scattering cross section. In this conference, we will report on measurement results of the spatial polarization distribution of linearly and circularly polarized LCS gamma-rays. The polarization axis of the polarized gamma rays was clearly measured to vary with scattering and azimuth angle. In the near future, we plan to use the developed polarimeter to also measure the spatial polarization distribution of gamma rays generated by an axially symmetric polarized laser ** .

Speaker: Yuxuan Yang (Zhengzhou University, Institute for Molecular Science, Shanghai Institute of Applied Physics)

16:00 SPS-II machine imperfections and optimization

SPS-II was designed for low emittance storage ring with
compact Double-Triple Bend Achromat (DTBA) cell. To
ensure sufficient machine performance, realistic machine
imperfections were simulated and incorporated into the optimization
process.Thus the lattice solutions were made robust
against imperfections, thereby reducing the machine’s sensitivity.
The solution with sufficient dynamic aperture and
lifetime can be found in the presence of imperfections. The
simulation steps and optimization will be discussed in this
work.

Speaker: Thapakron Pulampong (Synchrotron Light Research Institute)

16:00 Status of Sirius operation with users

SIRIUS is a state-of-the-art synchrotron light source facility, featuring a 3 GeV electron storage ring with a 518 m circumference and 250 pm·rad emittance. Built and operated by the Brazilian Synchrotron Light Laboratory (LNLS) in Campinas, Brazil, SIRIUS has undergone significant upgrades over the past year. These include the installation of a cryogenic plant, superconducting RF cavities, in-vacuum undulators, and new orbit feedforward systems, among others. This report summarizes these developments, highlights improvements in beam stability, and provides an overview of the facility’s operational status over the past year.

Speaker: Gabriel Ascenção (Brazilian Synchrotron Light Laboratory)

16:00 Status of the seeding upgrade for FLASH2020+ project

In the framework of the FLASH2020+ project, the FLASH1 beamline will be upgraded to deliver seeded FEL pulses for users. This upgrade will be achieved by combining high gain harmonic generation and echo-enabled harmonic generation with a wide-range wavelength-tunable seed laser, to efficiently cover the 60^-4 nm wavelength range. The undulator chain will also be refurbished entirely using new radiators based on the APPLE-III design, allowing for polarization control of the generated light beams. With the superconducting linac of FLASH delivering electron beams at MHz repetition rate in burst mode, laser systems are being developed to seed at full repetition rates. In the contribution, we will report about the progress of the project.

Speakers: Eugenio Ferrari (Deutsches Elektronen-Synchrotron DESY), Mathias Vogt (Deutsches Elektronen-Synchrotron DESY)

16:00 Studies on virtual platform for the HALF beamline

The autonomous alignment and optimization of syn-chrotron beamlines pose significant challenges. Tradi-tionally, manual alignment is a time-consuming and ex-perience-dependent process, often requiring extensive diagnostic efforts and data collection. With the construc-tion of the Hefei Advanced Light Facility (HALF) under-way, 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 im-prove 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.

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

16:00 Study of DESY II as an injector option for PETRA IV storage ring

PETRA IV is the storage ring light source currently under design at DESY in Germany. The baseline injector is a 6-GeV synchrotron DESY IV, an upgrade to the existing injector DESY II. Even if the project progresses in developing the DESY IV, we studied the intensity limit of DESY II to investigate the feasibility of reusing the existing injector chain, in view of a possible upgrade to a laser plasma injector in the coming years. We identified the microwave instability-induced energy spread and the transient beam loading as a limiting mechanism of single-bunch intensity in a 12.5 Hz cycle synchrotron. This paper reports the numerical simulation, its analysis, and its follow-up experiments of high charge acceleration at DESY II and its subsequent injection into PETRA III. The injection efficiency of DESY II's beam into future PETRA IV is also computed assuming imperfect lattices with 5% beta-beating. To overcome the intensity limit set by the pre-accelerator PIA, we investigated the possibility of multi-cycle accumulation at low energy. In this regard, we measured the lifetime and emittance over cycles and the chromaticities of the lattice. These are also reported in the paper.

Speaker: Chao Li (Deutsches Elektronen-Synchrotron DESY)

16:00 Study of the phase jump method for FEL oscillator

We propose a phase jump method to improve the electron beam conversion efficiency in FEL oscillator. A fast phase shifter is put between two undulator segments to kick the phase of the electron beam at saturation. The theoretical and simulation results are given based on FELiChEM which is built in Hefei. They indicate that a phase jump value of approximately π at saturation can significantly increase the gain and thus improving the FEL power. Taking 30μm wavelength as an example, the output power is increased by about 2.75 times than before.

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

16:00 Study on optimization of FEL generation in HX and SX lines for two-bunch operation

PAL-XFEL comprises two lines: Hard X-ray (HX) line for 2.5-15 keV FEL and Soft X-ray (SX) line for 0.25~1.1 keV FEL. Both lines share accelerator sections L1, L2, L3A, and two Bunch Compressors (BCs). The electron bunch is accelerated to 2.8 GeV and compressed to a peak current of 400-500A using accelerators and two BCs, then it is directed into either the HX or SX line at the branch line. Since the optimal RF phase settings for the two lines are different in the shared sections, we perform simultaneous operation by adjusting the LLRF settings of shared accelerator sections on a pulse-by-pulse basis. We are preparing for simultaneous operation using the two-bunch operation method to fully utilize the repetition rate for both lines. This method involves injecting two GUN lasers with a 25 ns delay into a single pulse, generating two bunches per pulse, and sending them simultaneously to the HX and SX lines. For two-bunch operation, the device settings of shared sections must be identical, we have re-optimized the HXFEL and SXFEL to have identical device settings for the shared sections. In this paper, we present the detailed optimization process and the final optimized parameters.

Speaker: Haeryong Yang (Pohang Accelerator Laboratory)

16:00 Study on pre-bunched free electron laser in the terahertz wavelength range

We have been studying about a pre-bunched FEL in the THz region. In the pre-bunched FEL, the electron bunches being compressed shorter than the oscillation laser wavelength, it is expected that we can generate short-pulse THz laser pulses with high peak intensity. A broadband spectrum and high-intensity characteristics, which cannot be realized by conventional FEL, are expected. The pre-bunched FEL experiments were conducted using the THz-CUR at Kyoto University Free Electron Laser (KU-FEL) consists of an existing electron rf gun (ECC-RF-Gun), which can produce short electron bunches adequate for pre-bunched FEL, and a 10-period undulator. We installed an optical cavity and performed beam tests at the lasing frequency of 0.2 to 0.4 THz. As the results of beam test, we observed the coherent stacking of coherent THz pulses inside the cavity, however, FEL oscillation has not been achieved yet. We will report on our pre-bunched FEL project, experimental setup, beam test results and future prospects.

Speaker: Tatsuki Kobayashi (The University of Tokyo)

16:00 Study on the characteristics of the XFEL beam source in the hard X-ray beamline at PAL-XFEL

Understanding the characteristics of the beam source is crucial for designing optimal beamline optics. During the construction of PAL-XFEL, simulation studies on the characteristics of the XFEL beam source were conducted in advance to aid in the design of beamline optics and experimental instruments. However, since the facility began providing user services in 2017, the performance of PAL-XFEL has been continuously improving. Consequently, it is anticipated that the characteristics of the XFEL beam source have changed from those at the time of initial construction. Despite this, measurement-based studies on the XFEL beam characteristics have not yet been conducted. Recent experimental results have revealed discrepancies between the design values and the observed focal position and size of the XFEL beam when it is focused using the compound refractive lens installed in the experimental hutch of the beamline. In this presentation, the current characteristics of the XFEL beam source in the hard X-ray beamline at PAL-XFEL will be discussed based on simulations and experiments. The characteristics of the XFEL beam source in the planned hard X-ray beamline will also be addressed.

Speaker: Chi Hyun Shim (Pohang Accelerator Laboratory)

16:00 Study on the linear model of the wiggler in the storage ring

As proposed in Ref[1], a fully coherent synchrotron light source requires a high-current, low-emittance storage ring with very short damping time to deliver a high-quality beam for the bypass line, ultimately producing high average power EUV radiation. The initial design adopts 8 TBA (Triple Bend Achromat) cells, with four cells forming one superperiod. The straight sections on either side of each super-period are designed with high beta functions, while the internal straight sections feature low beta functions. Each low-beta straight section includes three super-conducting sandwich-type damping wigglers to facilitate the I transformation, which increases radiation losses and significantly reduces the damping time. Overall, the ring is equipped with 18 superconducting damping wigglers.

Speaker: Yujie Lu (Shanghai Advanced Research Institute)

16:00 Sub 100 keV hard X-ray inverse compton sattering experiment at BNL ATF

Recent progress on the experiments of Inverse Compton Scattering (ICS) at Brookhaven National Laboratory Accelerator Test Facility (BNL ATF) is introduced. Nominal e-beam parameters utilized are electron beam energy of 70 MeV, charge per pulse of 0.5 nC with normalized emittance of 2 mm mrad. Use of long wavelength TW CO2 laser, and short wavelength Nd: YAG or Ti: Sapphire lasers allows us to explore unique nonlinear dynamics of Compton scattering such as Bi-Harmonic interaction and emission of Orbital Angular Momentum of X-ray. Currently, up to 90 keV hard X-ray yield from counter collision of Nd: YAG laser and 70 MeV electron beam is in a range of 1E6 photons per single pulse. Planning to increase electron beam energy to achieve establishment of sub 100 keV ICS to provide sufficient photon flux density, in the range of 1E10 per pulse, owing to the long wavelength multi TW  CO2 laser and tighter electron beam focus is underway.

Speaker: Mikhail Polyanskiy (Brookhaven National Laboratory)

16:00 Switchable X-ray orbital angular momentum from a cavity-based free electron laser

X-ray vortices carrying tunable Orbital Angular Momentum (OAM) are an emerging tool for X-ray characterization technology. However, in contrast to the generation of vortex beams in the visible wavelength region, the generation of X-ray vortices in a controlled manner has proved challenging. Here, we demonstrate an X-ray free-electron laser oscillator (XFELO) can adjust only the kinetic energy of the electron beam to produce vortex beams that can be programmed to dynamically change between different OAM modes, without the need for additional optical elements. With the nominal parameters of currently constructing 1 MHz repetition rate facility (i.e. SHINE), the active formation of the OAM modes of l = ±1 and l = ±2 and the rapid switching between them by detuning the electron beam energy of the XFELO are numerically illustrated. The real-time switching can be achieved within 200 μs, while the output pulse energy can reach the 100 μJ level. This result extends the capabilities of XFELOs, and paves the way for advanced at-source applications using X-ray vortex beams.

Speaker: Nanshun Huang (Shanghai Zhangjiang Laboratory)

16:00 Tapering enhanced superradiance - tapering rate optimization using analytical magnetic field maps

THz sources are typically very limited in power, making high-power sources scarce. One of the most promising THz sources are the Free Electron Lasers (FELs), which can generate high-power THz radiation using an undulator structure. Undulator radiation is an incoherent synchrotron spontaneous emission whose energy is proportional to the number of particles in the beam (𝑁). By longitudinally bunching the charged particle beam, a coherent spontaneous emission is generated and referred to as a super-radiant emission. Unlike spontaneous emission, super-radiant energy yield is proportional to N^2.
However, like typical FELs, the energy conversion efficiency is rather low. Here, we demonstrate a novel THz source structure based on a radiative interaction scheme of super-radiance – Tapered Enhanced Super-radiance (TES), which employs a tapered (amplitude) undulator in the zero-slippage condition. This method yields a significantly more powerful and efficient THz radiation source. An optimization algorithm was developed to obtain a tapering rate that yields the most efficient energy conversion from the electron beam to the radiation field.

Speaker: Leon Feigin (Ariel University)

16:00 The data acquisition system on vibration evaluation and predictive maintenance for cooling water pumps system in TPS

The purpose of this paper is evaluating vibration status for cooling water pump system in TPS. The utility systems operate continuously since TPS commission in 2014. The predictive maintenance based on vibration level and spectrum became more important, especially for those unstoppable operate water pump systems. The vibration monitoring system started to construct in 2017 and upgraded in 2023. After vibration test over several months and years, some components of the cooling water pumps found abrasion and mismatched. The recorded data showed vibration level increase irregularly over ISO 10816 standard. The spectrum showed the detail status in the pump system. The cooling water pump systems repaired and maintained base on vibration evaluation after vibration evaluation. The utility systems could prevent malfunction at least over one month through regular vibration inspection and daily data acquisition. The data acquisition system for pump systems on vibration evaluation provided the predictive maintenance enough time to solve the problem and avoid system suddenly shutdown.

Speaker: Yung-Hui Liu (National Synchrotron Radiation Research Center)

16:00 The generation of ultrafast seeded free-electron lasers at S3FEL

The field of ultrafast science has seen substantial growth over the past decade. High-power, ultrafast free-electron lasers (FELs) have become essential tools across various scientific disciplines, including physics, chemistry, and biology. The shorter pulse durations enable enhanced temporal resolution in pump-probe experiments. This paper introduces methods for generating ultrafast seeded free-electron lasers at the Shenzhen Superconducting Soft X-Ray Free-Electron Laser (S3FEL). The mechanisms underlying the proposed approaches are discussed in detail, along with corresponding simulation results.

Speaker: Li Zeng (Institute of Advanced Science Facilities, Shenzhen)

16:00 The high harmonic radiation with mild energy modulation based on storage ring

The synchrotron radiation generated by storage rings offers numerous advantages, including high stability, a broad photon energy range, and the capacity to support multiple users simultaneously. However, one notable limitation is its poor radiation coherence. Achieving coherent harmonic generation (CHG) in storage rings would not only significantly enhance the coherence of the emitted light but also dramatically improve specific spectral ranges, internal luminous flux, brightness, and energy resolution. However, the realization of higher order harmonic radiation usually requires higher energy modulation. In this paper, a relatively mild energy modulation scheme is proposed to generate higher harmonic radiation based on storage rings. Lower energy modulation is achieved by using a lower power laser, and then an additional self-modulation section is introduced to enhance the bunching factor of harmonics. Three-dimensional time-dependent simulation results based on the parameters of Hefei light source-II show that the modulation amplitude is reduced by half under the same harmonic radiation power, which can greatly improve the tolerance of the modulation to the momentum aperture in the ring and reduce the damping time to achieve coherent radiation with higher repetition rate.

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

16:00 Towards gamma-ray free-electron lasers

The free-electron laser (FEL), powered by an accelerator and equipped with an undulator, produces intense coherent radiation at ever-shorter wavelengths. Whilst the hard x-ray regime represents the current state of the art, the gamma-ray regime remains the next objective. Gamma-ray lasers, deemed one of the most profound and intriguing challenges in physics by the 2003 Nobel Laureate, hold the key to unlocking the largely unexplored nuclear domain. This article introduces a novel scheme that harnesses FEL harmonics, offering a pathway for existing x-ray FELs to operate as gamma-ray lasers.

Speaker: Dr Alan Mak (Science and Technology Facilities Council)

16:00 Ultrafast free-electron laser generation with optical beat note

As one of the most important frontiers of international science and technology, the development of ultrafast science has provided important research tools for many disciplines. Free-electron laser (FEL) has the unique advantages of high power and short wavelength in generating ultrafast pulses. In this paper, the theoretical simulations were performed to produce the ultrafast pulses, utilizing an electron beam compressed by an optical beat note. The main parameters used in the simulation are from Shanghai Soft X-ray Free Electron Laser Facility (SXFEL). The results show that an isolated FEL pulse with the peak power of 700 MW and the pulse duration of ~1 femtoseconds can be generated. In addition, we discuss the effect of the relative delay jitter of optical beating laser on ultrafast radiation. The result shows that the scheme is very sensitive to time delay jitter.

Speaker: Yaozong Xiao (Shanghai Optoelectronics Science and Technology Innovation Center)

16:00 VPuRD: virtual pulse reconstruction diagnostic for single-shot measurement of free electron laser

Accurate characterization of radiation pulse profiles is crucial for optimizing beam quality and enhancing experimental outcomes in Free Electron Laser (FEL) research. In this paper, we present a novel approach that employs machine learning techniques for real-time virtual diagnostics of FEL radiation pulses. Our advanced artificial intelligence (AI)-based diagnostic tool utilizes longitudinal phase space data obtained from the X-band transverse deflecting structure to reconstruct the temporal profile of FEL pulses in real time. Unlike traditional single-shot methods, this AI-driven solution provides a non-invasive, highly efficient alternative for pulse characterization.
By leveraging state-of-the-art machine learning models, our method facilitates precise single-shot measurements of FEL pulse power, offering significant advantages for FEL science research. This work outlines the conceptual framework, methodology, and validation results of our virtual diagnostic tool, demonstrating its potential to significantly impact FEL research.

Speaker: Najmeh Mirian (Helmholtz-Zentrum Dresden-Rossendorf)

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-ray domain to achieve 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 X-ray laser oscillator - new results

X-ray Laser Oscillator (XLO) is an ongoing project at SLAC National Accelerator Laboratory. The project aims to construct world's first population inversion x-ray laser, using LCLS XFEL as a pump. XLO also utilizes the multi-bunch mode of LCLS copper linac, and a Bragg cavity arranged in a bow-tie configuration. When built, XLO will be able to generate x-ray pulses of very high quality. In this proceeding, we report on the new findings and design updates of the XLO.

Speaker: Aliaksei Halavanau (SLAC National Accelerator Laboratory)

16:00 → 18:00 Monday Poster Session: MOPM

16:00 A high-peak-power, phase-stabilized laser system for quasi-steady-state microbunching

Steady-State Microbunching (SSMB) proposes a novel mechanism for generating high-average-power coherent radiation spanning from THz to EUV, with significant potential for various applications. This paper presents the development of a laser system tailored to serve as the modulation laser for the second phase of the SSMB proof-of-principle (PoP) experiments. To verify the stability of microbunching, we have developed a 1064 nm laser system with a burst-mode time structure, achieving peak power exceeding 20 kW. Ensuring the stability of the electron bunches' turn-by-turn phase within the storage ring is crucial for coherent modulation. To address this, we employ an iodine-frequency-stabilized CW seed laser and implement a phase-locking loop. Measurements show that the phase error is below 0.1%π, fulfilling the experimental requirements. The laser system is scheduled for shipment to Berlin, Germany, where it will be integrated with the MLS quasi-synchrotron ring at HZB for the SSMB PoP II experiment.

Speaker: Zhou Yang (Tsinghua University)

16:00 A numerical study on injection efficiency improvement at SuperKEKB electron ring

SuperKEKB is an asymmetric lepton collider with 7-GeV electron and 4-GeV positron beams. The current vertical beta function (βy) at the collision point is set to 1 mm. Experimental results confirm that reducing βy leads to narrower dynamic apertures in both the horizontal and vertical directions, which in turn decreases the beam injection efficiency. This study presents a numerical investigation aimed at improving injection efficiency to achieve higher beam luminosity.

Speaker: Takashi Yoshimoto (High Energy Accelerator Research Organization)

16:00 A proposal of a momentum collimator in RHIC warm section for controlling experimental background at sPHENIX

One of the issues that the AuAu 100 GeV physics program in 2024 in RHIC encountered was background in the sPHENIX MVTX detector, which causes autorecoveries and preventing continuous data taking. Beam studies and track simulations performed to understand the source of the background and potential measures to control it have led to the conclusion that off-momentum particle loss was an issue. This article will focus on a proposal of a momentum collimator in warm sections in RHIC to control the MVTX background. We will elaborate the selection of the locations for the collimator, the strategy of generating substantial horizontal dispersion there, the required additional powering scheme for selected quads and the optimization of the figure-of-merit for momentum collimation.

Speaker: Henry Lovelace III (Brookhaven National Laboratory)

16:00 Accelerator and Compton gamma-ray source research program at Duke University

The accelerator and Compton gamma-ray source research program at Duke Free-Electron Laser Laboratory (DFELL), TUNL, is focused on the development of the storage ring-based free-electron laser (FEL) and a state-of-the-art Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS) driven by the storage ring FEL. With a maximum total flux of about 3.5E10 gamma/s and a spectral flux of more than 1,000 gamma/s/eV around 10 MeV, the HIGS is the world's highest-flux Compton gamma-ray source. Operated in the energy range from 1 to 120 MeV, the HIGS is a premier Compton gamma-ray facility in the world for a variety of nuclear physics research programs, both fundamental and applied. In this work, we will describe our recent FEL development to enable the production of gamma rays in the higher energy range from 100 and 120 MeV. We will also provide a summary of our recent activities in accelerator and FEL physics research and Compton gamma-ray source development.

Speaker: Ying Wu (Duke University)

16:00 Advancing the feasibility study of the ALICE fixed-target experiment using crystal-assisted halo splitting with HL-LHC lead ion beams

The Large Hadron Collider (LHC) at CERN is the world’s most powerful particle accelerator, capable of colliding proton and lead ion beams at energies up to 7 ZTeV. ALICE, one of the LHC’s key experiments, is designed for studying heavy-ion collisions. A proposed fixed-target experiment within ALICE involves directing a portion of the beam halo, extracted using a bent crystal, onto an internal target positioned a few meters upstream of the detector. For proton beams, this configuration has already demonstrated effective particle flux delivery to the target while operating safely alongside standard beam-beam collisions. However, with lead ion beams, the beam halo comprises nuclei of varying charge, mass, and magnetic rigidity, posing additional operational challenges. This paper presents an analysis of the expected performance, based on multi-turn particle tracking simulations using a detailed LHC model.

Speaker: Marcin Patecki (Warsaw University of Technology)

16:00 Automated conditioning utilizing machine-learning: first experimental results

The conditioning of room temperature cavities is a long process. Additionally, since the cavity or auxiliary equipment can be damaged, constant supervision or extensive safety precautions are required. To reduce the workload for everyone involved and to increase the efficiency of the conditioning process, it was decided to develop a machine learning algorithm with the goal of fully automated conditioning in mind.
The initial model was trained on available data of the low energy-domain (up to 500 W). Since it was possible to expand the data to higher power levels during conditionings in 2024, the algorithm is now trained for power levels up to 30 kW. In this paper, the challenges of training with different power scales, as well as the first experimental results shall be discussed.

Speaker: Stephan Wagner (Goethe University Frankfurt)

16:00 Automation of pulse identification at J-PARC

At J-Parc, the 500 μs long macro-pulses generated by the LINAC are separated into intermediate-pulses to synchronize it to the frequency of the Rapid-Cycling-Synchrotron (RCS). To secure a stable operation, the knowledge of position and length of those intermediate pulses are crucial, as the pulses need to be adjusted to the RCS frequency. The measurement for this adjustment is done by a beam position monitor (BPM), positioned directly behind the LINAC section in the low energy beam transport (LEBT) section. Since the form of the detected pulses can vary, the implementation of classical algorithms for the automatic detection and identification of pulses proofed unreliable. Because of that, it was decided to develop a machine learning algorithm for the automatic pulse identification. In this paper, the background, training and results of different machine learning algorithms developed for the described problem will be introduced and discussed. Additionally, a test of the developed program during active beam operation is being planned, and will be introduced.

Speaker: Stephan Wagner (Goethe University Frankfurt)

16:00 Baseline concept and future prospects for the FCCee collider top-up injection

The FCC-ee (Future Circular Collider) is a high-luminosity lepton collider study at CERN. Strong effects from quantum fluctuations, beamstrahlung, and Bhabha scattering limit the expected lifetime to well below one hour. Top-up injection continuously refills the colliding bunches to maximize the integrated luminosity.
The current baseline aims at using conventional on-axis injection and a thin magnetic septum. However, the beam size at higher energy modes and the limited off-energy dynamic aperture at lower energy modes make the on-axis condition challenging to achieve. The conventional scheme also raises machine protection concerns, as the circulating beam is subject to a fast one-turn bump towards the thin septum during the injection process.
This contribution presents the status of the top-up injection scheme for every energy mode of the FCC-ee collider. We then discuss the existing challenges and potential variations to the baseline scheme in view of mitigating operational challenges and machine protection risks.

Speaker: Laurent Ducimetière (European Organization for Nuclear Research)

16:00 Bayesian methods and differentiable models for optics studies at the ISOLDE facility

The Isotope mass Separator On-Line facility (ISOLDE) delivers a wide range of low-energy radioactive ion beams to its experimental users. To meet varying demands, the facility uses different target materials, ionization methods, and cooling/bunching techniques, with beam configurations potentially changing weekly. To model particle transport through the transfer lines, it is essential to reconstruct the beam's initial transverse phase space for each setup, achieved via quadrupole scan measurements. This work explores the application of Bayesian techniques and differentiable models to reduce the time required to perform the beam setup.

16:00 Bayesian optimization for IP aberration correction and luminosity tuning in FCC-ee

FCC-ee luminosity optimization relies on measuring realistic signals from Bhabha scattering, beamstrahlung, and radiative Bhabha photons. Initial assessments of beamstrahlung signals examine the change in luminosity, beamstrahlung power and vertex detector hits in response to waist shifts, vertical dispersion and skew coupling at the collision point. These ongoing studies aim to extract IP-aberration-related signals from the energy spectrum, angular distribution, power of beamstrahlung photons, the vertex detector hits and the luminosity. Furthermore, the study integrates all these signals into a machine-learning-based approach for luminosity tuning and optimisation.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

16:00 Beam dump transfer line design in FCC-ee

The Future Circular lepton Collider (FCC-ee) will be an e+e- collider with beam energy spanning from 45.6 GeV to 182.5GeV. When operating in Z-mode, it will deliver the highest luminosity ever obtained in any lepton machine worldwide, and the stored beam energy will reach up to 18 MJ. Due to synchrotron radiation damping, the beam vertical size will be on the order of a few tens of um corresponding to a maximum energy density of ~5 GJ/mm^2 in the collider ring.

A dedicated beam dumping scheme is required to safely dispose this potentially disruptive beam. A transfer line is designed to increase the beam transverse size as much as possible and reduce the energy density of the beam at the dump. This contribution presents the dump transfer line design for the collider ring as well as related studies on machine protection.

16:00 Beam losses due to beam-residual gas interactions in the FCC-ee

The Future Circular electron-positron Collider, FCC-ee, is a design study for a luminosity-frontier and highest-energy e+e- collider with a 91 km circumference. In a circular machine, the interactions between the beam particles and the residual gas in the vacuum chamber may degrade the beam quality, potentially affecting the beam lifetime and the collider luminosity, and cause local beam losses. In addition, experimental backgrounds may be increased. Ideally, the vacuum system must be able to keep vacuum conditions sufficiently good so that beam-residual gas interaction effects are tolerable for collider operation. This paper presents a study of the beam loss distribution arising from beam-residual gas interactions in the FCC-ee, together with beam-gas lifetime estimates.

Speaker: Giacomo Broggi (European Organization for Nuclear Research)

16:00 Beam tracking simulation of the capture LINAC for the ILC e-driven positron source

In the electron-driven positron source of the International Linear Collider (ILC), positrons are generated through electromagnetic showers by irradiating a target with a 3 GeV electron beam and then accelerated in a positron capture linac in a solenoid magnetic field. Because of the high current multi-bunch beam requirements of ILC, the beam loading effect is one of the important issues. In order to identify engineering issues, a test bench has been set up at the KEK-STF to build and test prototypes of a target system, a flux concentrator, an accelerating tube and a solenoid coil. Based on this test bench arrangement, a beam tracking simulation of the positron source from target to the upstream of the capture linac has been started by PIC simulation using the com­mer­cial code CST studio. In this contribution, the results of beam tracking simulation with the realistic magnetic field, accelerating field and placements of components and the effects of beam loading on beam energy and yield will be reported.

Speaker: Masafumi Fukuda (High Energy Accelerator Research Organization)

16:00 Beam transverse jitter damping along the Future Circular Collider e+ e- linacs

Transverse stabilization of the beam in accelerators is crucial for optimizing any machine’s performance. The most common method for minimizing transverse beam jitter is the Balakin-Novokhatsky-Smirnov (BNS) damping technique. While this method has been successfully implemented worldwide, it has limitations in terms of beam quality preservation and acceleration efficiency, primarily because the accelerating structures are operated off-crest. In this work, we propose an alternative approach to induce the necessary energy spread while keeping the RF accelerating cavities operated on-crest. We applied this approach to the design of the Future Circular Collider (FCC) linacs, which are designed to achieve a beam energy of up to 20 GeV. From simulations we expect to maintain the transverse beam jitter increase below few percent compared to the initial one in a full length of about 1 km, optimizing the transverse beam quality and maximizing the energy efficiency. This method is general and can be applied to any accelerator.

Speaker: Simona Bettoni (Paul Scherrer Institute)

16:00 Beam-based alignment techniques for the FCC-ee

The Future electron-positron Circular Collider (FCC-ee) is a proposed lepton collider for high-energy particle physics succeeding the Large Hadron Collider (LHC). Its ambitious design goals demand excellent orbit and optics control and, therefore, set strict limits on alignment tolerances. One approach to relax the mechanical alignment tolerances is Beam-Based Alignment (BBA), where the offset between magnet and position measurement is determined and can later be used to steer the beam towards the magnetic centre using corrector magnets. One of the key challenges of the FCC-ee is developing an accurate and fast BBA strategy for quadrupoles and sextupoles. A parallel BBA technique is evaluated and compared in simulations for the baseline and an alternative lattice for FCC-ee using Xsuite and is presented in this paper.

Speaker: Micha Reissig (Karlsruhe Institute of Technology)

16:00 Benchmarking the LHC impedance model through loss of Landau damping measurements and simulations

Refining the present longitudinal impedance model is essential for an accurate prediction of beam stability thresholds. Longitudinal loss of Landau damping (LLD) for single bunches were observed in the Large Hadron Collider (LHC). For High Luminosity (HL-) LHC beams, the present stability margin is aimed to be maintained. While coupled-bunched instability has not been detected in the LHC so far, it may become an issue at HL-LHC parameters. Recent studies have shown that broad-band impedance contributions and their cut-off frequencies affect the LLD threshold. In this contribution, results from the analysis of the machine development studies of 2024 are presented and compared to macroparticle tracking simulations, as well as LLD threshold predictions using semi-analytical solvers. Their discrepancies are discussed, and potential sources are investigated.

Speaker: Birk Emil Karlsen-Bæck (European Organization for Nuclear Research)

16:00 CETASim: a numerical tool for beam collective effect study in storage rings

We developed a 6D multi-particle tracking program CETASim in C++ to simulate intensity-dependent effects in electron storage rings. The program can simulate the beam collective effects due to short-range/long-range wakefields for single/coupled-bunch instability studies. It also features the simulation of interactions among charged ions and the trains of electron bunches, including both fast ion and ion trapping effects. The bunch-by-bunch feedback is also included so that the user can simulate the damping of the unstable motion when its growth rate is faster than the radiation damping rate. The particle dynamics is based on the transfer maps from sector to sector, including the nonlinear effects of amplitude-dependent tune shift, high-order chromaticity, and second-order momentum compaction factor. Users can also introduce a skew quadrupole useful for emittance sharing and exchange studies. This paper briefly introduces the code structure and gives benchmark studies for single and coupled bunch effects. PETRA-IV H6BA lattice parameters are applied as test-bed.

Speaker: Chao Li (Deutsches Elektronen-Synchrotron DESY)

16:00 Coherent plane ground wave impact on the FCC-ee beam centroid

The FCC-ee is a collider, proposed after the LHC era, based on a ring of approximately 90 km of circumference. It will have to be able to accommodate beams running at half the z-pole and tt ̅-pole with vertical Interaction point beam size less than 40 nanometer at the z. In the present studies, coherent ground motions are being explored with particle tracking tools such as MAD-X and analytics code. The effect of parameters, such as harmonics, phase, orientation, defining global vertical sine waves like motion, are hence being detailed. At the time of writing, several lattices are subject to investigations. The differences in term of beam centroid for the main lattices and energy running will also be exposed. The impact of these motions of the machine detector interface quadrupoles is discussed.

Speaker: Mael Le Garrec (European Organization for Nuclear Research)

16:00 Collimator damage study for the Diamond-II storage ring

To understand the risk of damage to the collimator blades and the permanent magnets in Diamond-II, the BDSIM code has been used to model the beam losses. To improve the accuracy, the engineering model and 3D field maps have been used to build the machine model. Energy deposition in the main storage ring components and the fluence of secondary particles (particularly neutrons) have been determined. This paper explains the simulation process and give the BDSIM tracking results.

Speaker: Dr Hossein Ghasem (Diamond Light Source)

16:00 Combining quadrupole-driven slow extraction with RFKO at the CERN SPS

The CERN Super Proton Synchrotron (SPS) employs quadrupole-driven third-integer slow extraction to deliver beam to the North Area. This process is controlled by ramping all the magnets in the lattice, gradually driving the circulating beam into the tune resonance. In medical synchrotrons, Radio-Frequency Knock Out (RFKO) has proven to be a reliable alternative for driving the extraction process while maintaining good spill quality. Inspired by these efforts, a hybrid scheme was tested in the SPS, where a transverse exciter was used to apply a sinusoidal excitation in parallel with the magnetic ramp. It is demonstrated that this setup improves spill uniformity both in simulation and measurements.

16:00 Commissioning of the new FLASHlab@PITZ beamline extension

Over the past year a new beamline dedicated to R&D for electron FLASH cancer radiation therapy and radiation biology was set up at the Photo Injector Test facility at DESY in Zeuthen (PITZ). The beamline runs in parallel to the SASE THz beamline at PITZ and is connected to it with an achromatic dogleg. The dispersion within the dogleg is utilized to install an aperture to scrape off-energy dark current. The following straight section of the beamline contains a kicker system which will be capable of distributing electron bunches from a single bunch train freely over an area of 25mm x 25mm within one millisecond. So far, only the slow kicker for the vertical plane is installed – the fast kicker for the horizontal plane will be installed soon. Behind an exit window is an experimental area for conducting irradiation experiments with the 22 MeV electron beam, which can accommodate setups for a wide range of experiments.
Here we report the completion of the construction of the new beamline with detailed information about the setup. Preparation results of the PITZ robot and further data of the new experimental area are described. Additionally some new simulation results are given.

Speaker: Matthias Gross (Deutsches Elektronen-Synchrotron DESY)

16:00 Comparison of BCMS and standard beams at LHC injection energy

During the Large Hadron Collider (LHC) run in 2024 two beam types were used for physics production with protons. A key difference between the standard 25 ns and the batch compression merging and splitting (BCMS) beams at injection into the LHC, is the smaller transverse emittance achieved with the latter in the injector chain. Despite both beam types appearing indistinguishable in the longitudinal plane, the BCMS beam caused significantly higher beam losses at the start of the acceleration ramp. For the High-Luminosity LHC (HL-LHC) era, start-of-ramp losses could a limitation due to a lack of RF power. It is therefore important to understand the origin of the increase, as both beam types may be used for operational runs after the HL-LHC upgrade. Systematic analysis of the emittance evolution in all three planes have been conducted to investigate the contribution from loss mechanisms like intra-beam scattering (IBS) and RF background noise. Furthermore, estimates of the beam population outside the bunches and start-of-ramp losses are provided to understand the differences in the off-momentum population before the ramp.

Speaker: Birk Emil Karlsen-Bæck (European Organization for Nuclear Research)

16:00 Comparison of particle in cell and soft-Gaussian beam-beam solvers

A crucial component for designing particle colliders is the assessment of beam-beam effects at collisions. Particle In Cell (PIC) solvers are popular numerical tools, which solve the Poisson equation for the electromagnetic (EM) potential
$\Phi$ produced by the colliding beam's bunches spread on a discretized grid, and compute the Lorentz force acting on the particles subjected to the gradient of $\Phi$. The main limitation of this approach is the high computational cost, which can be alleviated at the expense of accuracy by using approximation techniques, such as the soft-Gaussian approximation, which assumes the bunch particles to have transverse Gaussian distributions. Both methods are widely used in the accelerator physics community. The Xsuite framework is the first multiparticle tracking tool, which aims to support both approaches. This contribution compares the performance of their Xsuite implementation.

Speaker: Peter Kicsiny (European Organization for Nuclear Research)

16:00 Comparison of Xsuite simulations with measured backgrounds at SuperKEKB

Xsuite is a collection of packages developed to simulate beam dynamics in particle accelerators. It includes Python modules (Xobjects, Xpart, Xtrack, Xcoll, Xfields, Xdeps) that can be seamlessly integrated with one another and with both accelerator-specific and general-purpose Python tools, enabling the study of complex simulation scenarios. The Xcoll module, developed for collimation studies, allows the integration of beam-matter interaction simulations in the tracking through different available scattering models, including those in the BDSIM/Geant4 toolkit. Originally developed for the Future Circular e+e- Collider (FCC-ee) collimation simulation needs, the Xsuite-BDSIM/Geant4 interface is now deployed in full production for FCC-ee collimation studies. A key aspect of such studies relying on complex simulations is their benchmarking against measured data. This paper presents a first comparison of Xsuite collimation simulation results with measured data at the SuperKEKB e+e- collider.

Speaker: Giacomo Broggi (European Organization for Nuclear Research)

16:00 Correction of Long-Range Beam-Beam Driven Normal Sextupolar Resonance Driving Terms

Beam-based studies at the LHC injection energy showed that compensation of the strongly driven sextupolar resonance, Qx+2Qy, improved both the dynamic aperture and lifetime of the beam, even when far from the working point and on the far side of the 3Qy resonance. Thus, a reduction of other strong normal sextupolar resonance sources was of interest. In 2024, the first measurements of resonance driving terms with long-range beam-beam (LRBB) interactions were performed. These showed that LRBB was driving the same Qx+2Qy resonance strongly when colliding, in agreement with model predictions. A correction was found for the strongest normal sextupole resonances using the existing sextupole corrector magnets in the LHC, obeying the constraints on the chromatic coupling and the maximum magnet powering. Beam-based tests to validate the response of this correction with non-colliding beams have been performed along with the testing of the LRBB resonance correction during LHC commissioning.

Speaker: Sasha Horney (European Organization for Nuclear Research)

16:00 Criticality of powering failure of the main bend circuits in the FCC-ee at the Z-pole energy

The electron-positron Future Circular Collider (FCCee) will have a first phase of operation at the Z-pole energy of 45.6 GeV. To reach the target luminosity, a total of 11200 bunches with $2.14 \times 10^{11}$ charges will be used, accounting for a stored energy of 17.5 MJ per beam. Given the small beam emittances, the beam energy density in turn reaches extremely high values. The potential to induce severe damage to the accelerator components must be carefully evaluated for different failure scenarii. The effects of a powering failure of one of the main dipole circuits are described and discussed. The time-dependent effects are simulated with the XSuite tracking code. The results, expressed in term of orbit shifts, optics changes and particle losses, show that this failure is highly critical. The fastest scenario in which the beam experiences a horizontal orbit excursion of 11$\sigma$ in three turns is analysed in detail. Interlocking and mitigation strategies have been evaluated and are discussed.

Speaker: Dr Christoph Wiesner (European Organization for Nuclear Research)

16:00 Cross-talk effect of adjacent impedance elements studied for the HALF storage ring

In the storage ring of a fourth-generation synchrotron light source such as the Hefei Advanced Light Facility (HALF), a multitude of vacuum elements interact with the beam current, thereby generating beam coupling impedance. This is a crucial factor contributing to beam instabilities and affecting the machine performance. Conducting impedance analysis on a vacuum element-by-element basis, without accounting for the cross-talk effect between adjacent elements, may result in an imprecise impedance model. This could subsequently have a detrimental impact on the accuracy of beam dynamics analysis. In this paper, we will utilize CST electromagnetic simulation software to model adjacent impedance elements in the HALF storage ring, with a view to conducting a comprehensive investigation into the cross-talk effect.

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

16:00 Damage potential and machine protection criticality of the FCC-ee beams

The lepton beams of the Future Circular Collider FCC-ee will store 17.5 MJ of energy per beam during Z mode operation. The damage potential of these beams is an essential input for the design of the machine protection system. In this paper, first, the stored energy and energy density of the FCC-ee beams are reported and compared with the values for the Large Hadron Collider (LHC) and the High-Luminosity LHC (HL-LHC). Then, results of energy deposition studies using FLUKA for the generic scenario of a direct beam impact on graphite are presented. Due to the small beam sizes and the distinct shower development, the FCC-ee beams cause peak energy depositions that for Z mode intensities can be comparable to the LHC proton beams. In a last step, the initial hydrodynamic response of the material is simulated using ANSYS Autodyn for a round beam featuring an equivalent peak energy deposition. The calculated temperature rise and density depletion are presented and discussed.

Speaker: Dr Christoph Wiesner (European Organization for Nuclear Research)

16:00 Damping ring and transfer lines for FCCee Injector complex

A novel damping ring design and related transfer lines for the FCCee are proposed. The presented damping ring layout is optimized for operation at 2.86 GeV to efficiently cool both electron and positron beams and should cool down the transverse emittance of the positron beams by four orders of magnitude. The system accommodates beam trains consisting of 4 bunches separated by 25 ns, with a repetition rate of 100 Hz. Different layouts, including triangular and hexagonal geometries, have been investigated, utilizing various base arc-cell configurations such as FODO, six-bend achromat, and 10-bend structures. In addition to the damping ring, this contribution presents the design of transfer lines from the positron and electron sources to the damping ring, and the extraction lines from the damping ring to the high-energy LINAC. The design ensures rapid damping while maintaining beam quality, leveraging advanced lattice configurations. This work outlines the conceptual design, beam dynamics studies, and the technical challenges addressed to meet the demanding operational requirements of the FCCee injector system.

Speaker: Antonio De Santis (Istituto Nazionale di Fisica Nucleare)

16:00 Design of the FCC-ee injector linacs up to 20 GeV beam energy

The FCC-ee injector complex aims to deliver tunable, high-charge electrons and positron bunches for injection into a collider operating at center-of-mass energies from 90 to 365 GeV. The injector complex includes multiple linacs that sequentially boost the energy of the bunches to the booster injection energy of 20 GeV. This work addresses the significant challenges posed by the required beam parameters. We designed the electron (up to about 3 GeV) and the high energy (up to 20 GeV) linacs to provide very limited emittance growth due to static imperfections, maximum acceleration efficiency, excellent stability of the beam transverse jitter, and to match the requirements on the bunch length and single- and multi-bunch energy spread as well. An energy compressor system has been foreseen, to provide flexibility to scan beam charges across a wide range without compromising the final energy spread. This paper summarizes the comprehensive design and optimization studies conducted, demonstrating that the proposed linac system meets all current requirements for efficient injection into the booster ring, paving the way for the ambitious operational goals of the FCC-ee accelerator complex.

Speaker: Simona Bettoni (Paul Scherrer Institute)

16:00 Development of a step motor system for TPS Linac RF system

The linear accelerators of the Taiwan Photon Source has been fully operating for more than 10 years. Considering components’ aging issues and a shortage of supply chain due to phase-out parts, an alternative solution for these components with the same functionality must be prepared in case of need in order to ensure the TPS Linac’s smooth operation. In this report, a new 6-axis step motor controller is built. This controlling system could be used in TPS Linac’s radio frequency (RF) power distribution system and RF phase adjustment. Moreover, this new established system can replace the original one and it can be used as spare components. This report introduces in detail of this controlling system, including motor’s selection, step motor controller and its controlling software.

Speaker: Ching-Lung Chen (National Synchrotron Radiation Research Center)

16:00 Do transverse bunch tails produce luminosity?

Heavily populated transverse beam tails can be an issue for the operation and the performance of present and future particle colliders. In this respect, the tailoring of beam distributions through transverse halo scraping is a powerful technique for limiting beam losses and maximizing beam lifetime. By doing so, a portion of the bunch intensity is sacrificed, to the benefit of a reduced bunch transverse emittance. In this paper, we assess the impact on the luminosity performance of the LHC using such bunches, based on an analytical approach supported by numerical integration. In particular, we quantify the interplay between beam scraping, bunch intensity loss, transverse emittance reduction and collider luminosity performance.

Speaker: Sofia Kostoglou (European Organization for Nuclear Research)

16:00 Dual-purpose structure for light and heavy particles

A dual-purpose structure has been developed for the NICA collider accelerating heavy multiply charged ions and light polarized nuclei of protons and deuterons. For heavy multiply charged ions, it is necessary to solve the problem of intrabeam scattering, which requires minimal modulation of the envelope and dispersion function. For light particles, the problem of crossing transition energy arises. In the proposed structure, both problems are solved due to a specially developed structure of magnetic arcs. This magneto-optical structure can be used to accelerate both heavy ions and light polarized protons and deuterons without loss of beam quality.

Speaker: Aleksei Melnikov (Russian Academy of Sciences)

16:00 Emittance tuning of the FCC-ee high energy booster ring

The Future Circular Collider (FCC), in its leptonic configuration has been chosen by CERN as main proposition for the next high-energy collider. This project aims to achieve luminosities one to two orders of magnitude higher than ever. Feasibility studies have led to the definition of tolerances on magnet imperfections and correction strategies. This is crucial for ensuring the performance of one of the main elements of the acceleration chain, the High Energy Booster (HEB) ring. The efficiency and overall performance of these strategies greatly influence new magnet specifications and tolerances, affecting main optic functions. Horizontal and vertical orbit corrections use horizontal and vertical kickers, respectively. Skew quadrupoles address vertical dispersion and transverse coupling. Normal quadrupoles correct the horizontal and vertical phase advances. This study simulates the distribution of these four corrector types to minimize the equilibrium emittance at the extraction energy of 45.6 GeV. The calculated strengths of these correctors and the associated misalignments are presented. The study also discusses the limitations and drawbacks of the proposed correction strategy.

Speaker: Rogelio Tomas (European Organization for Nuclear Research)

16:00 Energy sensitivity of the High Luminosity LHC optics at the end of the Beta* squeeze

During 2022 and 2023 LHC optics commissioning, it was observed that at low-beta small changes in the beam-energy could generate substantial perturbations of the linear beam optics, requiring re-commissioning of local corrections in the experimental insertions. This issue may become even more significant at the very low beta anticipated for operation in the High Luminosity LHC (HL-LHC). Furthermore, energy drifts, for example due to the terrestrial tides, have generally been ignored during LHC optics commissioning, with no regular corrections applied during the duration of a specific measurement campaign. This paper examines the anticipated sensitivity of HL-LHC optics corrections to energy errors at end of the beta* squeeze.

Speaker: Sasha Horney (European Organization for Nuclear Research)

16:00 Estimation of FCC-ee beam lifetime from full lattice tracking

Across its energy range, the beam lifetime at the Future Circular Collider $e^+e^-$ (FCC-ee) will be dominated by radiative processes occurring as a result of the beam-beam collision, namely by beamstrahlung and small angle radiative Bhabha scattering. Although approximate analytical expressions exist for estimating the lifetime, it is most accurately evaluated by performing multiparticle tracking simulations, due to the interplay of magnetic errors with non-linear forces due to the beam-beam interaction. This contribution presents the first comprehensive study of the FCC-ee beam lifetime including both effects, simulated with the Xsuite framework.

Speaker: Peter Kicsiny (European Organization for Nuclear Research)

16:00 Estimation of systematic errors in the experiment on precise mass measure of Y(1S)-meson on the VEPP-4M collider

Error analysis and estimation of accuracy in the experiment on precise mass measurement of Y(1S)-meson on the VEPP-4M with KEDR detector collider was presented. The resonant depolarization technique with laser polarimeter was used for beam energy calibration.

Speaker: Vadim D. Kashkin (Budker Institute of Nuclear Physics)

16:00 FCC-ee energy calibration and polarization - Status and outlook

The Future electron-positron Circular Collider, FCC-ee, aims at high-precision particle physics experiments with beam energies from 45.6 to 182.5 GeV, corresponding to the Z-pole up to above the top-pair-threshold. These goals demand, among others, a precise knowledge of the center-of-mass energy and, hence, the beam energies. By depolarizing previously polarized pilot bunches and recording the change of polarization with a 3D polarimeter, it is aimed to determine the spin tune and thereby achieve a systematic uncertainty on the beam energy in the order of tens of keV. The latest progress of the work conducted by the FCC-ee energy calibration and polarization working group is reported here.

Speaker: Tatiana Pieloni (École Polytechnique Fédérale de Lausanne)

16:00 FCC-ee ground motion model and SuperKEKB relevant experimental characteristics

The proposed FCC-ee machine is a high-energy, high-intensity and high-precision lepton collider which will require to reduce drastically the differential motions of its two beams at the interaction points (IPs). All undesirable effects on the beam parameters must be analysed in detail, especially in the vicinity of the IP but also along the collider. To assess the beam effects due to vibrations, simulation of magnet motion is necessary. A specially designed ground motion generator, applicable to several locations, is presented. It can take into account the seismic motions and cultural noises observed at the various experimental sites as well as amplifications due to specific mechanical assemblies, such as magnet mounts.
To match as much as possible to reality, the generator can be refined with SuperKEKB data. It is an asymmetrical lepton collider which presents many similarities with FFC-ee. In this article, dedicated measurements on this experiment, which are relevant to the FCC-ee ground motion generator, are described such as transfer function of the last cantilever cryostats behaviors, critical magnet supports resonances, and evaluated coherence at various points locations.

Speaker: Gael Balik (Institut National de Physique Nucléaire et de Physique des Particules)

16:00 FCC-ee Interaction point optics correction with alignment errors using local tuning knobs

Optics tuning and correction in the Interaction Point (IP) region of the FCC-ee is critical for achieving the target luminosity. By utilizing dedicated IP tuning knobs, lattice errors at multiple IP's are corrected to restore the design optics, enabling dynamic aperture studies on the fully corrected lattice. These studies, conducted using the pyAT optics code, assess the impact of corrections and the effectiveness of various tuning knobs in mitigating beam size growth at the IP's while maintaining beam stability. Benchmarking of pyAT results with the Xsuite framework ensures the reliability and robustness of the analysis. This approach provides valuable insights into the precision of IP optics tuning and its role in optimizing the collider's operational performance.

Speaker: Satya Sai Jagabathuni (European Organization for Nuclear Research)

16:00 FCC-ee optics tuning studies with pyAT and Xsuite

The FCC-ee is a future high-luminosity circular electron-positron collider aiming at achieving unprecedented luminosities with beam energies ranging from 45.6 up to 182.5 GeV. FCC-ee demands precise optics tuning to achieve its ambitious performance goals. This study investigates the tuning and correction of FCC-ee optics under simulated magnet misalignments, with a particular focus on the stringent initial alignment tolerances required in the Interaction Region (IR). Random misalignment errors were introduced, and correction algorithms were applied to recover the nominal lattice configuration using the pyAT optics framework. Post-correction dynamic aperture studies were conducted to assess the stability and resilience of the lattice under realistic operational scenarios. Benchmarking pyAT outcomes against the Xsuite framework validated the reliability and consistency of the corrections. The study offers valuable insights into alignment tolerance limits, correction methodologies, and their implications for beam dynamics, providing essential guidance for the development and operation of the FCC-ee.

Speaker: Satya Sai Jagabathuni (European Organization for Nuclear Research)

16:00 FCC-ee radiation environment and shielding

The secondary radiation fields generated by synchrotron photons pose a significant challenge for equipment in high energy electron and positron storage rings like the Future Circular Collider (FCC-ee) at CERN. The annual ionizing dose can reach MGy-levels in the FCC-ee tunnel and requires the design of a dedicated radiation shielding enclosing the photon stoppers in dipoles. In this paper, we present a first optimization of the shielding design, taking into account different aspects such as shielding efficiency, engineering and integration constraints, raw material costs, and radiological considerations. We demonstrate that the proposed shielding solution can decrease the dose in the tunnel by about two orders of magnitude, which considerably reduces the need of expensive radiation-hard equipment. In addition, we explore the option of housing accelerator electronics in a dedicated bunker near lattice quadrupoles, which can possibly allow for custom-off-the-shelf-based radiation tolerant electronics systems. We quantify the expected radiation levels in this bunker, which are driven by photo-neutron production by the high-energy component of the synchrotron spectrum.

Speaker: Dr Jerzy Manczak (European Organization for Nuclear Research)

16:00 Feasibility of kicker systems for FCC-ee and injectors

CERN’s Future Circular Collider (FCC) comprises a ~91 km circumference lepton collider and its injector complex. This contribution summarises the feasibility studies performed for the various kicker systems needed to transfer the beam between the different machines. The individual system requirements are reviewed, recent changes are highlighted, and the chosen conceptual design is outlined. Particular effort has been made to harmonise the hardware parameters across the machines to minimise the number of different beam line element types. The feasibility of the design parameters and technology options is discussed for both beam line elements and pulse generators. Early system integration aspects and implications on subsystems such as pulse transmission cables are also discussed. Consequences of the more restrictive requirements on the abort gap length in the collider are analysed.
This contribution concludes with recommendations for detailed studies and prototyping required to ensure a viable parameter space for the upcoming detailed technical design phase.

Speaker: Konstantinos Papastergiou (European Organization for Nuclear Research)

16:00 Generation of GeV-range photons via Inverse compton scattering at the FCC-ee

This study explores the feasibility of generating high-energy photons, reaching up to 150 GeV, at the FCC-ee booster through inverse Compton scattering. The proposed scheme utilizes a laser within a Fabry-Perot cavity, enabling high repetition rates while minimizing recoil effects during individual collisions. This approach supports the potential use of the FCC-ee booster as a high-energy light source. The photon spectrum and energy distribution are analyzed, with simulation results presented for electron-laser interactions within the Fabry-Perot cavity.

Speaker: Illya Drebot (Istituto Nazionale di Fisica Nucleare)

16:00 ILC accelerator status

The international linear collider (ILC) is a Higgs Factory, where electron-positrons are accelerated by the linear accelerators using Superconducting RF (SRF) cavities to 125 GeV. In 2013, the GDE, an international organization of researchers, already compiled the TDR. It is currently being studied under the International Development Team (IDT). Especially, from 2023, the ILC Technology Network (ITN), specifically under the IDT, will work on the development through international cooperation. This presentation will show an overview of the ILC and the recent developments under the ITN. First, an overview about the latest proposed Higgs factories of more than 250 GeV energy will be given. Second, we introduce the ILC accelerator, including the design, key technologies, accelerator systems. Finally, an detailed ongoing key technology developments, such as SRF cavities, nanobeam, and sources, for ILC project over the next few years will also be presented. We believe that these accelerator developments are not only crucial for ILC development but also for the improvements of future accelerators and various industrial and medical applications.

Speaker: Hiroshi Sakai (High Energy Accelerator Research Organization)

16:00 Impact of collective effects on beam stability in the FCC-ee main rings and the high-energy booster

The electron positron Future Circular Collider (FCC-ee) is considered the primary contender for the next major particle accelerator within the European Strategy for particle physics, aiming to achieve unprecedented luminosities to enable precise measurements of Z, W, and H bosons along with the top quark. Despite its potential, the FCC-ee project faces significant operational and design challenges, especially in managing collective effects such as space charge, wake fields, coherent synchrotron radiation, intra-beam scattering, and beam-beam interactions. The FCC-IS Feasibility Study brings together experts to address these challenges under one umbrella. This paper presents an updated status of the collective effects studies for FCC-ee main ring and high-energy booster, examining their implications and exploring potential mitigation strategies to prevent resulting instabilities.

Speaker: Dora Gibellieri (European Organization for Nuclear Research)

16:00 Impact of ground motion on FCC-ee performance

The Future Circular Collider for electron-positron collisions (FCC-ee) is a proposed next-generation particle accelerator aimed at achieving high luminosity and precision for fundamental particle physics experiments. Its performance is sensitive to environmental factors such as ground motion, which can induce vibrations and misalignments in critical accelerator components. This paper presents a detailed study on the impact of ground motion on FCC-ee performance, with a focus on beam stability, alignment tolerances, and the complex interplay between ground motion and operational parameters. Using advanced simulations and analytical modeling, we evaluate the FCC-ee's sensitivity to various ground motion scenarios, ranging from localized, uncorrelated disturbances to correlated plane waves, and analyze their effects on the beam optics, orbit distortions, and overall beam dynamics. The findings provide valuable insights into the design and operational strategies required to mitigate ground motion effects, guiding future research and engineering efforts to ensure the successful realization of the FCC-ee project.

Speaker: Kyriacos Skoufaris (European Organization for Nuclear Research)

16:00 Interplay between sextupole settings and single particle instabilities during the FCC-ee commissioning

The Future Circular Collider of electrons and positrons (FCC-ee) is designed to achieve high luminosity at center-of-mass energies ranging from the Z boson peak to the top quark threshold. During the commissioning phase, specialized optics are essential to accommodate the dynamic needs of machine tuning and beam stabilization. This paper investigates the role of sextupoles in the various FCC-ee commissioning optics, focusing on their influence on nonlinear beam dynamics. Using advanced simulation tools, we analyze how sextupole configurations impact key performance indicators, including the dynamic aperture, emittance evolution and lifetime. Strategies for optimizing sextupole strengths are explored. The findings provide critical insights for the design and optimization of the commissioning optics, ensuring efficient and reliable ramp-up to nominal operation. These results are instrumental in refining the FCC-ee commissioning strategy, supporting its broader objectives for particle physics research.

Speaker: Kyriacos Skoufaris (European Organization for Nuclear Research)

16:00 Investigation of octupolar resonances in the LHC

During operation for luminosity production, the LHC runs with very strong Landau octupoles to ensure the collective stability of the beams. A disadvantage of this is that these octupoles can drive resonances which can be detrimental to beam lifetime. Recently, a special optics configuration has been utilised to reduce the impact of the main octupoles on lifetime. This design relies on correctly modelling the resonance driving term (RDT) response to changes in these magnetic circuits. This paper presents beam-based studies comparing the RDT response to simulations where large discrepancies were found. To try and understand the source of this, several approaches were taken. Various methods including individual circuit measurements, studies of other circuits, and tests at different energy were employed but it remained challenging to localise the source of the discrepancy around the ring. This paper presents an attempt to apply and extend a segment-by-segment method, that has been very effective at identifying local linear optics errors, to non-linear errors through analysis of RDTs.

Speaker: Sasha Horney (European Organization for Nuclear Research)

16:00 Laser Compton backscattering for precision beam intensity control in the FCC-ee electron-positron collider

In this study, we explore the application of laser-driven Compton backscattering (CBS) as a method to precisely adjust and regulate the intensity of colliding particle bunches in the Future Circular Collider (FCC-ee). Maintaining a tightly controlled charge balance between collision partner bunches within a 3–5% tolerance is critical for mitigating the impact of beamstrahlung on bunch length and preventing flip-flop instabilities. We present a realistic design for the CBS optical beamline and provide detailed simulation results that demonstrate its performance in the FCC-ee. Our analysis includes the distribution of scattered positrons, illustrating the feasibility of CBS for achieving the stringent intensity control requirements in this next-generation collider.

Speaker: Illya Drebot (Istituto Nazionale di Fisica Nucleare)

16:00 Lattice correction and polarization estimation for the future circular collider e+e-

Precise determination of the center-of-mass energy at the Future Circular Collider (FCC-ee) operating at the Z and W resonance energies relies on resonant spin depolarization techniques, which require a sufficient level of transverse beam polarization in the presence of machine imperfections. In this study, the FCC-ee lattice is modeled and simulated under a range of realistic imperfections, complemented by refined orbit correction and tune-matching procedures. The equilibrium polarization is computed within these realistic machine models to investigate the causes of polarization loss and explore potential improvements through lattice optimization. Additionally, spin tune shifts, which contribute to systematic errors, are estimated to support the precision requirements of the energy calibration experiment.

Speaker: Tatiana Pieloni (École Polytechnique Fédérale de Lausanne)

16:00 Local and global betatron coupling correction based on beam position measurements in RHIC

Local coupling correction in Interaction Regions (IRs) and global coupling correction based on Base-Band Tune (BBQ) measurement have been performed routinely for RHIC operation. However, one still observes significant residual local coupling measured by beam position data. For the Electron-Ion Collider (EIC) project, betatron decoupling for the hadron beam needs to be improved to maintain a large horizontal to vertical beam emittance ratio (12:1). In this paper, we will analyze the cause for noticeable residual coupling in RHIC and propose an integrated local and global betatron coupling correction based on beam position measurements. We will also present experimental results from ML-based optimization of the local and global coupling in RHIC.

Speaker: Henry Lovelace III (Brookhaven National Laboratory)

16:00 Long-term alignment stability of the SuperKEKB tunnel

SuperKEKB is a double ring collider consisting of a 7 GeV electron ring and a 4 GeV positron ring with a circumference of 3 km built 11 m below the ground level.
SuperKEKB was constructed by reusing the KEKB tunnel, which was originally excavated for TRISTAN accelerator in early 1980s. SuperKEKB utilizes “large angle nano-beam scheme,” where two low emittance beams collide with a large crossing angle at the interaction point and therefore it is more sensitive to any machine errors, such as magnet misalignment, than KEKB.

Since the tunnel was built on soft ground, it has been seen that the initial magnet alignment is deteriorating year by year. Level changes of the monument markers on the tunnel wall and the floors on either side of the interaction point have also been observed. The vertical and horizontal positions of the cantilever cryostats of the final focusing superconducting magnet system are constantly monitored during the beam commissioning. The cryostat vertical position presents a correlation with the vertical vertex position in the Belle II detector. These variations and the effects of temperature and other environmental factors on alignment will be reported.

Speaker: Mika Masuzawa (High Energy Accelerator Research Organization)

16:00 Longitudinal beam dynamics tracking simulation for the triple radio-frequency system in electron storage rings

For diffraction-limited storage rings, the triple radio-frequency (RF) system has been proposed to achieve further bunch lengthening or to meet specific requirements for longitudinal injection. The choice of RF cavity parameters for the triple RF system has a significant influence on the longitudinal beam dynamics. Macroparticle tracking simulation is commonly used to accurately analyze this influence. In this paper, we extend the STABLE code [1] to study the dynamics of the triple RF system assumed for the Hefei Advanced Light Facility storage ring. It is found that there are two important factors that possibly limit the bunch lengthening.

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

16:00 Longitudinal wakefield implementation in the circulant matrix model

The influence of longitudinal wakefields on the beam dynamics in electron-positron colliders, particularly their role in beam instabilities such as Transverse Mode Coupling Instability (TMCI) and other transverse-longitudinal effects, necessitates a robust approach to accurately model these effects. This work focuses on the implementation of wakefield effects in the Circulant Matrix Model (CMM), a linear model that can facilitate the representation of these instabilities. We study the impact of potential well distortion and synchrotron frequency shifts due to longitudinal wakefields for FCC-ee and implement these effects in the CMM. The implementation is benchmarked against reference multiparticle tracking simulations to validate its accuracy in predicting longitudinal wakefield-driven instabilities. Results enable further studies featuring longitudinal wakefields for collider designs and operating machines.

Speaker: Roxana Soos (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

16:00 Machine learning approach to MDI optimization for 3 TeV c.o.m. Muon Collider

The Muon Collider is a proposed future accelerator for very high energy muon collision. Since muons are heavier than electrons, the synchrotron radiation is negligible at this high energy, allowing to build a compact machine able to deliver Multi-TeV c.o.m. energy collisions, enabling precision measurements of the Standard Model quantities and search for new physics. A challenge of a muon beam is the Beam-Induced Background (BIB), a flux of particles in the detector generated by secondary interaction of muon decay products with the accelerator components.
To deliver the required physics performance, the Machine Detector Interface design needs to include a shielding for the BIB. The proposed solution consists of cone-shaped tungsten shields inside the detector area. The nozzles reduce the BIB to a manageable level at the cost of reducing the detector acceptance. A careful optimization of the geometry is necessary to further mitigate the BIB and improving the detector acceptance to maximize the physics potential. This contribution aims at discussing the optimization achieved with machine learning algorithms in combination with FLUKA simulations for a 3 TeV c.o.m. Muon Collider.

Speaker: Luca Castelli (Sapienza University of Rome)

16:00 Magnet R&D for the muon collider: proposed R&D plans

The muon collider represents a transformative approach in particle
physics, offering a pathway to achieve high energy and luminosity with
reduced environmental impact compared to other collider technologies.
Central to its feasibility is the development of advanced magnet systems
capable of supporting the stringent requirements of muon production,
acceleration, and collision. The key targets for magnet R&D include
achieving field levels up to 40 T, magnets with stored energies up to
300 MJ, managing heat loads from muon decay at the level of several W/m,
and ensuring radiation resistance well above 50 MGy. Given such
extraordinary challenges, research presently focuses on integrating
high-temperature superconductors (HTS), tailored for efficient cooling
at cryogenic temperature, and striving for compact magnets to reduce the
capital expenditure. In the past years we have progressed in the
conceptual design, and in some cases initiated engineering
design as well as materials and small-size coil testing. This has
allowed to outline an R&D plan that we describe in this paper. The proposed plan involves staged milestones which include development of magnet prototypes.

Speaker: Siara Fabbri (European Organization for Nuclear Research)

16:00 Modelling optics and beam-beam effects of SuperKEKB with Xsuite

SuperKEKB, located at KEK, is a second generation B-factory, providing beam to the Belle-II experiment. Optics design and simulation of SuperKEKB were previously performed using the optics code SAD, developed at KEK. In this paper, we present a new model of SuperKEKB using the tracking code Xsuite, developed at CERN. An alternative strategy for modelling the interaction region, with controllable final focus quadrupoles, has been adopted. Optics comparisons between the new Xsuite model and existing SAD model, as well as tracking simulations including beam-beam modelling are presented.

Speaker: John Salvesen (European Organization for Nuclear Research)

16:00 Modelling resonant depolarisation

For the FCC-ee collider it is planned to, in regular intervals (minutes), measure the average beam energy of the circulating electron and positron beams with a relative precision of $10^{-6}$ or better, using the method of resonant depolarisation with pre-polarized pilot bunches. In this article, we study basic systematic effects and ultimate uncertainties that may arise in this kind of measurement. To do so, we carry out simulations for a simple model representing an ideal situation, where an ensemble of particles with energy spread is subjected to synchrotron oscillations and to perfect spin motion. We assume an initial spin orientation in the vertical direction for all particles. The behavior of the spin is explored as an exciter frequency is swept slowly or rapidly, and in either direction,through the spin resonance.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

16:00 Operational experience and design improvement studies of the LHC MKI cool

In view of the unprecedented beam intensities expected in the High-Luminosity era of the Large Hadron Collider (HL-LHC), an upgrade of the LHC injection kickers (MKIs) is currently underway. This upgrade aims to mitigate excessive beam-induced heating of the MKIs and to limit resulting vacuum activity. The first MKI Cool was installed in the LHC during the Year End Technical Stop (YETS) in 2022-2023, and the upgrade of the entire system of 8 injection kickers is expected to be completed during Long Shutdown 3 (LS3).
This paper discusses the operational performance of the new MKI Cool magnets and compares it to the magnets of the post-LS1 design. Additionally, it focuses on investigations aimed at understanding the observed results, with the goal of further enhancing the performance of the MKI Cool design.

Speaker: Konstantinos Papastergiou (European Organization for Nuclear Research)

16:00 Operational experience with automated beam loss analysis in the LHC

Every high-energy beam dump event at the Large Hadron Collider (LHC) is analysed to assess the performance of the machine protection system and to identify anomalous behaviour. Analysing the loss pattern of nearly 4000 beam loss monitors, which depends on beam parameters and machine settings, can be time-consuming and requires expert knowledge. Therefore, an automated beam loss analysis tool was developed and deployed in operation in November 2023. It uses empirically derived beam loss thresholds that scale with relevant beam parameters to evaluate beam dumps for post-mortem analysis. The paper describes how the beam loss thresholds were derived and optimised and reviews their performance in proton and Pb-ion operation.

Speaker: Dr Christoph Wiesner (European Organization for Nuclear Research)

16:00 Optics studies at the compact ERL

The compact ERL has been operated at the various beam optics as a test facility for industrial applications, such as the future EUV-FEL for a lithography. The short bunch length is the key for the high intensity SASE FEL therefore a tunable R56 of the arc optics is necessary for the bunch compression. We demonstrate the two kinds of arc optics: one is easy optics matching and another one is having a large energy acceptance. In addition, the deflector cavity is installed downstream of the undulators for the bunch length measurement. The beam optics is optimized for high resolution measurement. In this presentation, we show the summary of the optics tuning and the results.

Speaker: Dr Miho Shimada (High Energy Accelerator Research Organization)

16:00 Optics tuning of the FCC-ee

The Future Circular Collider, FCC-ee, is a proposed next generation electron-positron collider aiming to provide large luminosities at beam energies from 45.6 up to 182.5 GeV. This collider faces a major challenge to deliver the design performance in the presence of realistic lattice errors. A commissioning strategy has been developed including dedicated optics designs, efficient beam-based alignment and optics corrections based on refined optics measurements. First specifications on main magnets, corrector circuits, and instrumentation have also been investigated. A summary of all these aspects is presented in this paper.

Speaker: Rogelio Tomas (European Organization for Nuclear Research)

16:00 Optimisation of drift tube cooling and drift tube geometries of an additive manufacturing IH-type cavity

Additive manufacturing is a now-powerful tool for the rapid prototyping and manufacturing of complex geometries. A proof-of-concept 433 MHz IH-DTL cavity was constructed for direct additive manufacturing of linear accelerator components. The CFD analysis of the initially designed cooling for the drift tube revealed a design with insufficient heat dissipation; this can lead to thermal deformations as well as problems in keeping the frequency stable during operation. In this respect, an optimization of the cooling system was done in detail with the help of advanced thermal simulation and iterative design improvements.
Furthermore, the geometries of the drift tubes were refined to improve mechanical stability and thermal efficiency without compromising electromagnetic performance. The results illustrate that additive manufacturing can achieve significant design freedom, enabling new approaches toward the thermal management challenges faced by high-frequency linear accelerator components.

Speaker: Benjamin Dedic (Goethe University Frankfurt)

16:00 Optimized physics performance evaluation of monochromatization interaction region optics for direct s-channel Higgs production at FCC-ee

The measurement of electron Yukawa coupling ($y_{e}$) via direct s-channel Higgs production at $\sim$125 GeV centre-of-mass (CM) energy is significantly facilitated at the FCC-ee, provided that the CM energy spread can be reduced to a level comparable to the natural width of the Higgs boson. This reduction is possible through the “monochromatization” concept, which involves generating opposite correlations between spatial position and energy deviation in the colliding beams. Following initial parametric studies for this collision mode, three different interaction region optics designs, each featuring nonzero horizontal, vertical, or combined dispersion at the interaction point, have been proposed based on the Version 2022 of the FCC-ee Global Hybrid Correction optics. In this paper, we benchmark the upper limits contours on $y_{e}$ with simulated CM energy spread and luminosity using Guinea-Pig, in order to assess, optimize, and compare their physics performances.

Speaker: Angeles Faus-Golfe (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

16:00 Optimizing cavity detuning at high beam intensities in the LHC

The increased beam intensity during the high lumionsity LHC era is expected to impose tight margins on the operation of the LHC RF system. The larger momentum spread from the injectors together with twice the bunch charge requires a higher RF voltage at injection to avoid beam losses. However, the peak RF power due to the increased beam loading must be kept below the saturation level of the klystrons. Accurate optimization of RF parameters is therefore needed to maintain a sufficient RF voltage to capture and retain the injected beam. In the LHC, the beam-loading is partially compensated by detuning the RF cavities. This is achieved at injection by a pre-detuning scheme and throughout the injection plateau by applying half-detuning. During the 2024 run the pre-detuning was adjusted with beam to minimize the required peak power at injection. Furthermore, a new algorithm was developed to optimize the setup of the half-detuning scheme at a given bunch intensity. Both measures have been essential to accommodate higher beam intensities in the LHC.

Speaker: Birk Emil Karlsen-Bæck (European Organization for Nuclear Research)

16:00 Overview of power deposition profiles in the LHC off-momentum cleaning section in Run 3

Off-momentum losses at the start of the LHC acceleration ramp in proton runs gave rise to multiple beam dumps by exceeding Beam Loss Monitor (BLM) thresholds in the momentum cleaning insertion (IR3). Accurately estimating the power deposition profiles in IR3 is necessary to determine where BLM thresholds can be optimized, thereby reducing unnecessary beam dumps and improving machine availability and performance. Understanding the loss limits in IR3 is crucial for future High-Luminosity LHC (HL-LHC) performance.
In this study, we present FLUKA power deposition results and introduce a newly developed simulation model for BLM benchmarking in IR3. We provide a comprehensive overview of the power deposition in magnets and collimators, identifying potential bottlenecks in the system. Our simulations were benchmarked against multiple fills from 2023 and 2024 that led to beam dumps. The obtained results provide a deeper understanding of the IR3 collimation performance in view of HL-LHC operation in IR3.

Speaker: Volodymyr Rodin (European Organization for Nuclear Research)

16:00 Parameter and luminosity scenarios for FCC-hh

In preparation for the 2026 Update of the European Strategy for Particle Physics, various options are being proposed for a future circular hadron collider, FCC-hh. Here, we discuss a few operational scenarios spanning c.m. energies from about 70-120 TeV, which correspond to the arc dipole field strengths ranging from 12 to 20 T. We present the respective integrated luminosity forecasts, considering a proton beam current similar to the one of the existing LHC (0.5 A) or the upcoming HL-LHC (1.1 A), and limiting the total synchrotron radiation power to at most 5 MW. Additional constraints are imposed on the beam-beam tune shift and the maximum event pile-up.on the maximum event pile up.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

16:00 Performance improvement studies for the CERN SPS MKDH system

The CERN-SPS beam dump system (SBDS) is equipped with a dilution kicker system, the so-called MKDH. During the 2022 and 2023 beam commissioning, the vacuum rise in the MKDH became a concern for reaching the anticipated higher beam intensities. Dedicated conditioning of the SPS kickers enabled successful attainment of High-Luminosity (HL) beam intensities during 2024 operation. However, the conditioning time required after replacing an MKDH magnet remains a significant concern, leading to a study aimed at optimizing its high intensity performance. This paper presents a feasibility assessment, a detailed characterization of the operational kickers and the spare units, and proposed modifications designed to optimize the MKDH kicker magnet performance. The modifications focus on minimizing interactions and coupling between the kicker and the beam, with the ultimate goal of improving the operational efficiency with high intensity beams.

Speaker: Konstantinos Papastergiou (European Organization for Nuclear Research)

16:00 Phase space measurements of 90 mA and 52.5 keV H⁻ ion beam at J-PARC frontend

A 90-mA and 52.5-keV negative hydrogen ion (H⁻ ion) beam has been extracted from the J-PARC Radio Frequency (RF) H⁻ ion source. The 90-mA beam phase-space distribution at the entrance of the Radio Frequency Quadrupole (RFQ) cavity was measured at the test stand. Compared with the 60-mA beam condition for the present J-PARC user operation, reasonable increase in the operation parameters (the RF input power to the ion source, the electrostatic voltage for beam extraction, and the solenoid currents for Twiss matching with the RFQ) was observed. The normalized RMS emittance increased by a few 10 %, which is within the acceptable range of the RFQ. In addition, the dependence of the beam phase-space distribution was investigated with respect to the operation parameters. Numerical analyses show that the optimum solenoid current was determined to remove the beam halo component with the orifice in the beam transport section, which was originally installed for the differential vacuum pumping of the ion source and the RFQ. In the presentation, the effect between the beam current and the phase-space distribution are discussed in aspect of the H⁻ ion beam optics.

Speaker: Takanori Shibata (High Energy Accelerator Research Organization)

16:00 Positron contamination in the muon beam at the J-PARC's surface muon beamline (S-line)

The surface muon beamline at J-PARC provides high-intensity muon beams that are essential for advanced materials science research, particularly in techniques such as muon spin rotation/relaxation (μSR). However, positron contamination in the beam poses a significant challenge by introducing background noise that affects the measurement precision. Therefore, achieving high-purity muon beams is critical for improving experimental reliability and accuracy. In this study, the G4beamline Monte Carlo simulation toolkit was employed to model the transport of muons and positrons from the production target through the beamline. The system includes a momentum and charge-based separator followed by a collimating slit. While the current slit configuration effectively suppresses positrons, it also causes substantial muon loss of approximately 76%, which significantly reduces the usable muon flux for downstream applications. To address this issue, a detailed investigation into slit size was performed. The results indicate that modest adjustments to the slit aperture size can improve the muon-to-positron ratio while retaining a greater fraction of the muon beam. These results provide valuable guidance for optimizing beamline performance and improving the quality of muon-based experiments at J-PARC.

Speaker: Phanthip Jaikaew (RIKEN Nishina Center)

16:00 Power deposition studies for the FCC-ee halo collimation system

The Future Circular Collider (FCC-ee) at CERN requires a betatron and momentum collimation system for reducing particle backgrounds in the detectors, and for protecting the machine in case of excessive beam losses. The system is composed of primary and secondary collimators, which will be housed in one of the technical insertions of the 91 km ring. In this paper, we present a first assessment of the beam-induced power deposition in the collimators using FLUKA Monte Carlo simulations. We show that dedicated shower absorbers are needed in the collimation insertion, which intercept secondary particles from the halo collimators and reduce the energy leakage to the environment. A first optimization of the shower absorber configuration is presented, considering different absorber positions and absorber lengths. We demonstrate that the power absorption of the betatron collimation system can be increased from about 50% to over 80% by adding two shower absorbers between primary and secondary collimators.

Speaker: Dr Jerzy Manczak (European Organization for Nuclear Research)

16:00 Progress on the 10 TeV center-of-mass energy muon collider

A 10 TeV center-of-mass muon collider could serve as a next-generation high-energy lepton collider with substantial physics potential while offering a more compact footprint than other proposed machines. However, this collider presents unique challenges, largely due to the short lifetime of muons and their decay products. Specifically, the collider ring requires specialized designs to protect the magnets and detectors while ensuring negligible neutrino radiation at Earth's surface. The high required luminosity also imposes stringent constraints, including very small beta functions at the interaction points that lead to strong chromatic effects. To meet these challenges, high-field combined-function magnets are used to create a compact layout with minimal straight sections. Flexible momentum compaction arc cells are used to maintain short bunch lengths and local chromatic correction sections to address the chromatic aberrations from the interaction regions. This work presents recent advancements in the 10 TeV muon collider ring, including interaction region improvements to reduce beam-induced background and a study that investigates the impact of $\beta^*$ on the dynamic and momentum acceptance.

Speaker: Kyriacos Skoufaris (European Organization for Nuclear Research)

16:00 Progress towards evaluating different types of colliding beams for a future wakefield-based 10 TeV discovery collider

The 2023 P5 report and recent long-term planning efforts in high-energy physics emphasize the need for a future discovery collider operating at 10 TeV parton center-of-momentum (pCM). A promising candidate is a wakefield-based linear collider, offering various beam options. While conventional electron-positron collisions using flat beams are preferred, challenges with accelerating such beams in wakefield accelerators have led to exploring alternatives like round beams, electron-electron collisions, and gamma-gamma collisions.

To evaluate these alternatives, we introduce a modeling framework that assesses their discovery potential. This framework includes detailed simulations of beam dynamics during collisions, accounting for disruption and beamstrahlung effects, to calculate luminosity and particle densities. Geant-4 simulations evaluate detector backgrounds and inform realistic detector designs, enabling studies of physics benchmarks to estimate discovery potential.

We present preliminary results for different collision scenarios, highlight the framework's current limitations, and propose future improvements.

Speaker: Remi Lehe (Lawrence Berkeley National Laboratory)

16:00 Proof-of-principle experiment to reconstruct the trajectory of dust grains interacting with the LHC beams

Interactions of dust grains with the LHC beams cause beam losses that can
trigger premature beam aborts or even quenches of superconducting dipoles.
While the simulated
motion and ionisation of dust grains inside the proton beam are in good agreement with measured beam-loss data, a direct measurement of the dust movement is not available.

A novel method was developed that reconstructs the trajectory of a dust grain based on the different beam loss profiles of transversely displaced bunches.
A proof-of-principle experiment to validate the method using a thin wire to simulate the dust grain was performed in June 2024 at the LHC.
This paper describes the beam experiment,
compares the achieved displacements with simulations,
and shows the reconstructed trajectories.
Finally, it is discussed how the method can be applied for real dust events occurring during LHC operation.

Speaker: Dr Christoph Wiesner (European Organization for Nuclear Research)

16:00 Proposal of Z pole electron-positron ERL colliders

Electron-positron ERL colliders at the Z pole are proposed as a sustainability near future collider.The components are similar to the ILC accelerator, which consists of the linac with the 9 cell superconducting cavities, the 5 GeV damping ring, the beam delivery system for the final focus, and the electron and positron injectors. The recirculation loop is added to the ERL scheme. To fit it in the Tsukuba campus site of KEK, the accelerating gradient should be the same as the ILC of 30 MV/m, which can be achieved at 1 us RF pulse operation. Therefore, the energy recovery is imperfect because the return beam is delayed by the circulation time. In this presentation, we show the schematic views.

Speaker: Dr Miho Shimada (High Energy Accelerator Research Organization)

16:00 Radiation load from radiative Bhabha scattering in the FCC-ee experimental insertions

The lepton Future Circular Collider (FCC-ee) at CERN provides electron-positron collisions at four interaction points (IPs) along a 91 km ring, with beam energies spanning from 45.6 GeV (Z pole) to 182.5 GeV (ttbar threshold). The radiation showers produced by these collisions can reach sensitive components of the surrounding machine elements, possibly affecting their performance and lifetime. This contribution examines the case of radiative Bhabha scattering, which generates off-momentum beam particles that can be lost downstream. Some losses occur already at the superconducting final focusing quadrupoles (FFQs), where they can cause quenches and degradation of the coil materials. In this work, the Monte Carlo code FLUKA is used to study the impact of radiative Bhabha in the experimental insertion regions of FCC-ee. The radiation load in the FFQs and the radiation levels in the nearby tunnel and machine elements are simulated for the Z-pole and ttbar operational modes. For the FFQs, a tungsten shielding layer with optimized thickness is proposed to mitigate the radiation load in the magnet coils.

Speaker: Dr Jerzy Manczak (European Organization for Nuclear Research)

16:00 Refining dynamic aperture calculations for highly damped accelerators: methods and applications to the FCC-ee

The dynamic aperture is a key metric for assessing the stable phase space of particle accelerators and evaluating their overall stability. However, in highly damped accelerators such as high-energy electron synchrotrons like the Future Circular Collider (FCC-ee), the rapid amplitude variation of tracked particles over a few turns introduces significant sensitivity to initial conditions and the particle's starting location. This work investigates these dependencies in the context of the FCC-ee and highlights their implications for stability analyses. We propose novel, more reliable methods to compute the dynamic aperture that account for these effects, improving the accuracy of stability predictions. First results from the application of these methods to the FCC-ee are presented, demonstrating their potential for advancing the understanding of beam dynamics in next-generation accelerators.

Speaker: Tatiana Pieloni (École Polytechnique Fédérale de Lausanne)

16:00 RF design of the positron traveling-wave structure

The Super Tau-Charm Facility (STCF) is a new generation of electron-positron colliders being planned with a design center of mass energy of 2-7 GeV. In the concept design, the positrons produced by electron targeting are accelerated to an energy of 200MeV by three large-aperture accelerating structures, and then to 3.5GeV by several conventional accelerating structures. The aperture of large-aperture accelerating structures is maintained constant, and the group speed is controlled solely by adjusting the length of the nose cone for easier production. Pulse compressors are taken into account to increase the accelerating structures power. In this paper, the designs of 2m and 3m large-aperture accelerators are presented, both achieving gradients higher than 15 MV/m.

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

16:00 RHIC Au operation in Run24

The Relativistic Heavy Ion Collider (RHIC) Run 24 was 27 weeks, operating with collisions at the STAR and sPHENIX detectors. The secondary running mode was gold at 100 GeV/u, where there was 3 weeks of operation. The goals of this run were to: reach an intensity of 1.8e9 ions/bunch and fully commission the 56 MHz cavity, ensure sPHENIX systems are ready for Run25,and deliver 1-2e9 minimum bias events for STAR. Beam was delayed 1 week due to two simultaneous failures of essential kicker systems: an AGS extraction bump power supply, and the yellow RHIC abort kicker. Elevated backgrounds at sPHENIX’s MAPS-based VerTeX (MVTX) detector required extensive studies and diagnostics. With a combination of local steering at sPHENIX and a large amplitude bump in the sector 10 and 12 arcs, the background levels with 12 bunches were reduced by a factor of 18. STAR was able to collect over 1.5e9 minimum bias events and the 56 MHz cavity was operated near its full voltage at 700 kV with 1.3e9 ions/bunch. This paper provides a summary of the run and details of the background studies.

Speaker: Kiel Hock (Brookhaven National Laboratory)

16:00 Selected beam dynamics measurements at DAFNE

In 2024 DAFNE successfully completed the data delivery for the SIDDHARTA-2 detector largely exceeding the integrated luminosity requested by the experiment. This has allowed allocating the machine time for several dedicated beam dynamics experiments useful for both the collider characterization and for the design of future electron-positron colliders based on the crab waist collision concept.

Speaker: Antonio De Santis (Istituto Nazionale di Fisica Nucleare)

16:00 Simulations of losses from fast instabilities in the FCC-ee

The electron-positron Future Circular Collider (FCC-ee) is a proposed high-energy lepton collider that aims to reach unprecedented luminosity and precision in the measurement of fundamental particles. To fully profit of such performance, it is crucial to keep detector backgrounds under control and operate the machine safely. Due to the high stored beam energy and to a number of complex operational features required at FCC-ee (e.g. the top-up injection scheme), controlling the backgrounds to the physics experiments becomes even more challenging. Recent studies on collective effects have shown that high impedance in the FCC-ee can lead to fast rise-time instabilities, where the beam amplitude grows exponentially, leading to beam loss within a few turns. Although a feedback system is being developed to mitigate this instability, failure scenarios of this feedback system need to be explored. This paper presents the study of the effects of this instability, in order to understand the possible implications for the machine and the experiments.

Speaker: Giulia Nigrelli (European Organization for Nuclear Research)

16:00 Solid-state driven X-band linac for microcrystal electron diffraction

Transmission Electron Microscopes (TEM) require high voltage DC electron sources, which can quickly grow in size and cost at the higher energies required for standard TEM imaging. We present the progress on a low cost, compact solid-state-driven RF linac to replace high power electron guns in micro-crystal electron diffraction setups. The system accelerates electrons to 50 keV electrons with a 4 cell standing wave structure, where each cell is individually powered by an X-band solid-state amplifier. Future expansions on this design could function as a compact (order of 1 meter) source of electrons up to 1 MeV.

Speaker: Julia Sherman (Wellesley College)

16:00 Status of construction of the new heavy ion synchrotron SIS100 at FAIR

The construction of the new FAIR heavy ion accelerator facility at GSI is progressing well. With the start of installation of SIS100 an important new milestone in project execusion has been reached. SIS100 is the first superconducting, fast ramped synchrotron with special design features dedicated to the acceleration of high intensity, low charge state heavy ions. The full performance of the specific functional systems, stabilizing the dynamic vacuum at operation with high Uranium intensities in combination with high repetition rates, was recently demonstrated at the SIS100 string test. Even under the influence of eddy current heating of the chamber walls at high ramp rates, its separatly cooled cryogenic vacuum system assures a stabilization of the residual gas pressure at extremely low values. The first straight sectors and arc modules have been installed heading towards a first hardware commissioning in 2026.

Speaker: Lars Bozyk (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Status of the DELTA synchrotron light source

DELTA, a 1.5-GeV electron storage ring facility operated by TU Dortmund University in Germany, celebrated its 30th anniversary in fall 2024. During its time in operation, the facility has been continuously developed to provide synchrotron radiation (SR) users with the most reliable and attractive radiation source possible. This includes continuous improvements of electron beam stability and lifetime, the installation of a new 7-T superconducting wiggler magnet with a specially adapted SR outlet chamber, as well as the integration of a second solid-state amplifier-driven radiofrequency system. In recent years, there have also been many exciting developments in the field of accelerator physics. These include the construction of a facility for generating ultrashort and coherent SR pulses, studies involving laser-induced terahertz radiation, and experiments conducted in single-electron mode that complemented ongoing research activities. Furthermore, projects focusing on intelligent system control using machine learning methods were successfully implemented. This report summarizes the most significant developments over the past years.

Speaker: Detlev Schirmer (TU Dortmund University)

16:00 Status of the FLUTE RF system upgrade

FLUTE (Ferninfrarot Linac- Und Test-Experiment) is a new compact versatile linear accelerator at KIT. Its main goal is to serve as a platform for a variety of accelerator studies as well as a generation of strong ultra-short THz pulses for photon science. Also it will be used as an injector for a Very Large Acceptance compact Storage Ring (VLA-cSR) which will be realized at KIT in the framework of the compact STorage Ring for Accelerator Research and Technology (cSTART) project. To achieve acceleration of electrons in the RF photo-injector and linac with high stability, it is necessary to provide stable RF power. For this goal, an upgrade of the existing RF system design has been proposed and is currently being implemented. In this contribution an updated RF system design and the status of the RF photo-injector, linac and bunch compressor commissioning will be reported.

Speaker: Anton Malygin (Karlsruhe Institute of Technology)

16:00 Steady-state response matrix of radio-frequency cavity voltage in storage rings

The study of beam-cavity interaction is an essential step towards achieving the design objectives of high-intensity storage rings, particularly in the rapidly advancing fourth generation of synchrotron light sources, which rely on the strategy of bunch lengthening with harmonic cavities. Assessing the effectiveness of harmonic cavities typically requires self-consistently solving bunch equilibrium distributions, accounting for beam-loading voltages. This paper introduces a novel concept of the steady-state response matrix (SSRM) of radio-frequency (RF) cavity voltage: the steady-state beam-loading voltages are expressed as a product of the SSRM and an array containing only the information in bunch charge density distributions. Notably, the SSRM depends solely on RF cavity parameters such as R/Q, loaded Q, and resonant frequency. We demonstrate that the SSRM can significantly simplify and accelerate the self-consistent calculation of bunch equilibrium in double RF systems. Additionally, the SSRM can also facilitate the calculation for transient beam-loading feedforward compensation and the evaluation of thresholds for periodic transient beam-loading effect.

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

16:00 Study of single bunch effect in PETRA-IV storage ring

The H6BA lattice is now considered as the baseline design for PETRA-IV light source. It is required that the ring can be operated with and without damping wigglers, resulting in two sets of natural equilibrium beam parameters. This paper analyzes the single-bunch effects due to impedance in the H6BA lattice of PETRA-IV. We will show the influence of the impedance on the electron beam in both scenarios, with and without DWs. With the help of a 3rd harmonic cavity and a high chromaticity of 6 units, the single bunch current threshold exceeds 2 mA, leaving a 100% safety margin. At the nominal coupling of 0.1, the Touschek lifetime is larger than 10 hours in all operational scenarios.

Speaker: Chao Li (Deutsches Elektronen-Synchrotron DESY)

16:00 Study of the coherent < x-z > instabilities for FCC-ee

This work examines the dominant coherent head-tail type (< x-z >) instabilities in the vertical plane of the FCC-ee collider, focusing on a mode analysis method with the Circulant Matrix Model (CMM) to assess instability mechanisms under the influence of beam-beam effects and transverse wakefields. While the impact of vertical plane instabilities have been already studied, different mechanisms are prominent in the horizontal plane. Understanding these mechanisms is crucial to identifying a stable working point at the Z energy. This study aims to advance the stability analysis and optimisation of FCC-ee at Z energy by investigating horizontal plane dynamics. Our findings indicate that mitigation strategies effective for vertical plane instabilities may not be sufficient and need to be adapted in order to ensure overall beam stability.

Speaker: Roxana Soos (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

16:00 Tapering schemes for FCCee

The electron-positron Future Circular Collider (FCC-ee) is designed to operate at four beam energies, from 45.6 GeV to 182.5 GeV. At such energy levels, the circulating beam loses a significant fraction of its energy via synchrotron radiation. As a single RF insertion is foreseen in the ring, large closed-orbit shifts featuring a typical sawtooth pattern and optics distortions are induced. This in turn leads to a significant reduction of the dynamic aperture if no mitigation is implemented. The solution is to adapt the fields of the magnets to the local beam energy which is referred to as "tapering". For practical reasons, this field adjustment must be realized for groups of magnets to limit the number of powering circuits. An algorithm has bean established to self-consistently compute the tapering strengths of a given scheme, the RF phase required to compensate the energy loss and the required orbit corrections. Tapering scenarios, from coarse schemes to fine grained options are studied with the XSuite tracking code in terms of closed-orbit excursion and optics distortion. The results at the Z-pole (45.6 GeV) and $t\bar t$ (182.5 GeV) energies are discussed in detail.

Speaker: Dr Daniel Wollmann (European Organization for Nuclear Research)

16:00 Target luminosity and luminosity integral achievement at VEPP-2000 collider

VEPP-2000 electron-positron collider operating in the beam energy range of 150-1000 MeV is the only machine originally designed to exploit Round Beams Concept which results in significant beam-beam limit enhancement. After long shutdown for injection chain upgrade VEPP-2000 resumed data taking with luminosity limited only by beam-beam effects.

Thanks to extensive and thorough machine tuning the luminosity achieved L = 9 * 10^+31 cm-2s-1 at E=900 MeV that is above the design value. The stable operation resulted as well in high average data taking rate of 2-4 pb-1/day at top energies.

In 2024 VEPP-2000 achieved the symbolic long-term milestone: integrated luminosity recorded by each of two detectors, SND and CMD-3, exceeded 1fb-1. This value was the target data volume written in the project physical program. Recorded data allows to study physics of light quarks with unprecedent precision. Recently published by CMD-3 collaboration e+e- -> pi+pi- cross-section measurement already changed the vision of muon anomalous magnetic dipole moment mystery - possible window to physics beyond the SM.

Speaker: Yury Rogovsky (Russian Academy of Sciences)

16:00 The European Spallation Source neutrino Super Beam project and physics performance

The goal of the ESSnuSB project is to precisely measure neutrino Charge-Parity Violation (CPV). The construction of the European Spallation Source, ESS, represents an outstanding opportunity for such project to take place. ESSnuSB has been funded from EU in the framework of H2020 (2018-2022) and Horizon Europe (2023-2026) to make feasibility studies. The aim of the first phase was to demonstrate that the ESS linac can be used to generate an intense neutrino beam, which coupled with a megaton water Cherenkov detector placed in a mine 360 km from ESS, could allow the detection of neutrinos at the 2nd oscillation maximum. A CDR* has been published in which it is shown the unprecedented physics performance to precisely measure CPV. For this, the modification to compress the proton pulse length from 2.86 ms to 1.3 μs has been studied.
The second, ongoing Design Study, ESSnuSB+, is devoted to neutrino cross-section measurements relevant to ESSnuSB. Two facilities are proposed, a low energy nuSTORM (muons decaying to neutrinos in a storage ring) and a low energy ENUBET (pions decaying to a muon and a neutrino and monitoring of the neutrino beam by detection of the decay muon).

Speaker: Marcos Dracos (Institut Pluridisciplinaire Hubert Curien)

16:00 The mass production magnetic field measurement of the large aperture quadrupoles in HIAF

Currently the HIAF Project at IMP has reached the construction phase. The BRing is one of the key systems of HIAF, which is used to capture, accumulate, accelerate and extract the heavy ion beam injected by iLinac. The quadrupole magnets in BRing have large aperture (Ф260&Ф180) , large axial length(the total length of the magnet is reached 1140mm) and high integration field uniformity (±3×10-4). To measurement the magnetic field quality is very critical. The measurement aims to reach a reproducibility of 1.5×10-4 for the field integral, 2 ppm for the harmonic content for the main field and 0.2mm for the position of the magnetic center. A specially developed probe allows the simultaneous measurement of the field axis and quality. This thesis demonstrates that the system as it stands fulfils the high requirements with respect to the magnetic measurement and the magnetic center and thus provides the desired unique versatile equipment. The assessment was performed based on experimental results, direct calibration. The main defects treated are mechanical torsion and vibration of moving parts, electrical noise and power supply ripple.

Speaker: jing yang (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Towards a High Luminosity LHC with even higher performance

The High Luminosity LHC (HL-LHC) project aims to increase the integrated luminosity of CERN’s Large Hadron Collider (LHC) over its exploitation era up to the end of 2041 by an order of magnitude compared to the initial LHC design value. This requires doubling the bunch intensity along with several other important changes to the LHC configuration. Dedicated beam experiments in the LHC and its injectors have already demonstrated the feasibility of reaching many of the HL-LHC project design parameters, and simulations show that some parameters could be pushed to further increase the integrated luminosity or used as mitigation measures against potential shortcomings. This paper presents a review of the latest experimental results and the possible reach of the final HL-LHC parameters.

Speaker: Rogelio Tomas (European Organization for Nuclear Research)

16:00 Towards ATF3: Beam based alignment (DFS, WFS) corrections in the ATF LINAC and ATF2 beamline

The Accelerator Test Facility 2 (ATF2) serves as a critical platform for testing technologies and techniques aimed at advancing the next generation of linear colliders. The ATF2 is composed of a linear accelerator (LINAC), a damping ring, and an extraction line that includes a high-precision final focus system designed to achieve the small beam sizes necessary for future collider experiments. A key requirement for these systems is maintaining high beam stability to deliver the nominal beam parameters at the interaction point, where tight beam focusing and minimal emittance are crucial for optimal collision performance.
Recent efforts have focused on developing and implementing advanced beam correction techniques to enhance stability and counteract disruptive effects such as unwanted beam dispersion and wakefields to prepare for the ATF3 upgrade. These correction strategies have been tested across the LINAC, damping ring, and extraction line, showing promising results in mitigating these adverse effects. In particular, these methods have demonstrated the ability to reduce transverse beam oscillations and preserve beam quality, thereby improving the precision of beam delivery.

Speaker: Pierre Korysko (University of Oxford)

16:00 Transposition of the high-current beam transport strategy to new AIRIX functioning points obtained by increasing the diameter of the cathode

Experimental programs entrusted to the Franco-British EPURE facility require more and more flexibility with regard to the operation of different functioning points for our two Linear Induction Accelerators (LIA). In 2023, UPRX work (presented at IPAC'24) demonstrated our ability to control both reliability and repeatability of our first radiographic axis performances at high current (2.6 kA). To do this, a new strategy of electron beam transport based on the beam envelop constraint just downstream the injector module has been adopted, so as we managed to control BBU instabilities. In 2024, by increasing the diameter of the first radiographic axis cathode (from 63.5 to 70mm), we explored different “current/voltage” combinations and have demonstrated that the 2024 transport strategy could be transposed to the new generated beams at both 2.6 and 3kA (and a nominal 3.8 MeV energy at leaving from injector). We consequently proved our capacity to reach higher level of dose and a detailed analysis of the new beam initial conditions has highlighted the advantage of this new cathode, notably in view of optimizing the photonic focal spot size.

Speaker: Frédéric Poulet (Commissariat à l'Energie Atomique)

16:00 Updated monochromatization Interaction Region optics design for FCC-ee GHC lattice

Determining Yukawa couplings of the Higgs boson is one of the most fundamental and outstanding measurements since its discovery. The FCC-ee, owing to its exceptionally high-integrated luminosity, offers the unique opportunity to measure the electron Yukawa coupling through s-channel Higgs production at 125 GeV centre-of-mass (CM) energy, provided that the CM energy spread can be reduced from 50 MeV to a level comparable to the Higgs bosons’ natural width of 4.1 MeV. To improve the energy resolution and reach the desired collision energy spread, the concept of a monochromatization mode has been proposed as a new operation mode at the FCC-ee, relying on the Interaction Region (IR) optics design with a nonzero dispersion function of opposite signs at the interaction point (IP). A first optics design and preliminary beam dynamics simulations have been carried out for V22 of the FCC-ee GHC lattice type. In response to the continuously evolving FCC-ee GHC optics, this paper presents the first updated monochromatization IR optics design based on V23 of the FCC-ee GHC optics.

Speaker: Angeles Faus-Golfe (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

16:00 Upgrade of the LHC main RF system for HL-LHC

In the era of the High-Luminosity Large Hadron Collider (HL-LHC), the main RF system will be limited in voltage and power on the injection plateau due to strong beam loading. At the same time, significant start-of ramp losses, that are originating from capture and flat bottom losses, are expected and can severely impact machine availability or even prevent the beam from reaching the collision energy. In this contribution, we present the recent experience with high-intensity beams during operation and dedicated measurements to give an update on the estimated RF voltage reach for HL-LHC beam parameters. Projections for beam losses at capture, along the flat bottom, and at the start of the ramp are calculated, taking into account also the effect of intra-beam scattering. We discuss in detail the mitigation measures put in place, such as high-efficiency klystrons, the revision of beam loss monitor thresholds at the start of the ramp, and automatic working point optimization.

Speaker: Birk Emil Karlsen-Bæck (European Organization for Nuclear Research)

16:00 Y(1S)-meson rest mass measurement on the VEPP-4M collider

A new high precision measurement of the Y(1S)-meson rest mass is being carried out at the VEPP-4M collider using the KEDR detector. The resonant depolarization method with the laser polarimeter has been employed for the absolute calibration of the beam energy. In the paper resent status of the experiment is discussed.

Speaker: Vadim D. Kashkin (Budker Institute of Nuclear Physics)

16:00 → 18:00 Monday Poster Session: MOPS

16:00 10 years operation of the Solaris storage ring

The SOLARIS storage ring, Poland’s first synchrotron light source, has marked a decade of successful operation, contributing significantly to scientific research and technological advancement. Commissioned in 2015 and inspired by the innovative design of Sweden’s MAX IV Laboratory, SOLARIS exemplifies the effectiveness of international collaboration in cutting-edge accelerator technologies. Over the past 10 years, the facility has maintained high performance and reliability (97% availability), delivering high-quality photon beams to researchers in diverse fields. Continuous improvements in the accelerator systems, such as enhanced beam stability due to SOFB and FOFB implementation, and optimised maintenance schedules, have enabled SOLARIS to meet the growing demands of the scientific community. A key focus has been the development of new beamlines and experimental stations, broadening the scope of available research capabilities. Looking ahead, SOLARIS aims to further expand its infrastructure (linac upgrade, top-up injection) and enhance beamline performance, ensuring its continued role as a hub for innovation and scientific excellence.

Speaker: Adriana Wawrzyniak (SOLARIS National Synchrotron Radiation Centre)

16:00 A Dipole Scheme for the Electron Storage Ring at the Future Electron-Ion Collider

The Electron-Ion Collider, 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) at luminosities up to 10^34 cm−2 s−1. The electron storage ring will contain about 750 dipoles. These dipoles must fulfill not only complex geometric constraints but also requirements set by spin polarization. 576 dipoles will be located in the arcs and arranged as super-bend triplets, which provide reverse bending at 5 GeV to increase the emittance and damping decrement. The rest will be situated in the interaction region and insertion regions around the ring. Tight orbit tolerances driven by beam-beam effects at the interaction point result in very tight field-ripple requirements. While these could be mitigated by powering all dipoles in series, due to the super-bend configuration the dipoles do not all scale similarly with energy. A novel scheme has been developed using variable-turn coil designs and trim coils to achieve the required fields across the energy range. This contribution presents the unique dipole layout developed for the electron storage ring.

Speaker: Boris Podobedov (Brookhaven National Laboratory)

16:00 A FLASH-RT experimental platform and technology research progress

Compared with conventional radiation therapy, the toxic response of FLASH-RT dose rate is significantly reduced and the irradiation time is significantly shortened, and these advantages make FLASH-RT a hot spot in the current radiotherapy field. This paper investigates the development status of FLASH-RT at home and abroad, summarizes the challenges to achieve its clinicalization, and introduces a high-power linear accelerator converted into a Flash-RT experimental platform, with a brief introduction of its overall layout and the pulse modulator, microwave power source and microwave transmission system, control power cabinet, and circulating water cooling system. On the basis of the existing accelerator, the dosimetry is carried out by the detector, and the results show that the average dose rate reaches 60 Gy/s, which meets the requirement of the FLASH effect on the dose rate, and verifies the feasibility of generating the flash effect by this linear accelerator system.

Speaker: Meiyun Han (Peking University)

16:00 A muon beam facility at CERN to demonstrate muon ionisation cooling

The International Muon Collider Collaboration (IMCC) has been formed following the 2020 European Strategy for Particle Physics Update, with the goal of studying the feasibility of a muon collider at a centre of mass energy of around 10 TeV. One of the most challenging sections of a muon collider is the initial cooling before acceleration, due to the necessity to apply intense magnetic and electric fields to reduce the 6D emittance of the muon beam by 5 orders of magnitude in a very short time, to cope with the limited lifetime of muons (2.2 μs at rest). The IMCC proposes to build a Demonstrator to prove that all the involved technologies (RF, magnets, absorbers, beam instrumentation) can be built at the required specifications, and integrated in order to limit the length of the cooling sections to an acceptable value. Several options are being considered in different laboratories within the collaboration. This paper describes a possible implementation at CERN, in the existing TT7 tunnel.

Speaker: Daniel Schulte (European Organization for Nuclear Research)

16:00 Adiabatic capture in high-intensity, high-power rings

Finding the optimal RF voltage ramp to capture coasting beams in high intensity rings has been the subject of ongoing study for many decades. We are motivated to revisit the topic with a view to capturing coasting, stacked beams in a future high intensity, high power FFA. However, the results have general applicability. We compare various voltage laws including linear, bi-linear and iso-adiabatic through simulation and experimentally, making use of the ISIS synchrotron. Making use of longitudinal tomography, we seek to establish the voltage program that minimises the captured beam emittance.

Speaker: David Kelliher (Science and Technology Facilities Council)

16:00 ALBA II accelerator upgrade project status

ALBA is working on the upgrade project that shall transform the actual storage ring, in operation since 2012, into a 4th generation light source, in which the soft X-rays part of the spectrum shall be diffraction limited. The project was launched in 2021 with an R&D budget to build prototypes of the more critical components. The storage ring upgrade is based on a MBA lattice which has to comply with several constraints imposed by the decision of maintaining the same circumference (269m), the same number of cells (16), the same beam energy (3GeV), and as many of the source points as possible unperturbed. At present, the lattice optimization, iterating with the technical constraints of space and performance, is ongoing. This paper presents the situation of the project, with the present proposed lattice and equipment design; the status of the prototyping of magnets, pulsed elements. vacuum chambers, buttons BPMs, and girders; the proposed RF system with fundamental and harmonics cavities; and the general context of the upgrade.

Speaker: Francis Perez (ALBA Synchrotron (Spain))

16:00 Analysis and compensation of the insertion devices effect 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 have severe impacts on the low-energy beam. Especially for the long-period EPU, the non-linear effect can 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: Gangwen Liu (University of Science and Technology of China)

16:00 Applications of electron energy measurement based on resonant spin depolarization at BESSY II

An electron energy measurement based on resonant spin
depolarization has been running permanently at BESSY II
for several years. This high-precision energy measurement
was set up primarily for users of synchrotron radiation for me-
teorological applications from the Physikalisch-Technische
Bundesanstalt (PTB). Recent investigations have led to a
better understanding of the method and the possibility of
shortening the measurement time. This allows for new obser-
vations and the use of the energy measurement for different
applications such as the model-free measurement of the
natural chromaticity, the momentum compaction factor or
synchrotron sidebands.

Speaker: Anny Gora (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 Beam dynamic analysis of an electron microtron using General Particle Tracer

Beam Dynamic Analysis of An Electron Microtron Using General Particle Tracer.

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

16:00 Beam loading for counter-rotating high-intensity beams in the Muon collider

Muon colliders promise an efficient path to a multi-TeV energy collider facility. In the greenfield study, the final stage of the acceleration chain is planned as a series of four rapid-cycling synchrotrons (RCS). In each RCS, the RF systems are divided into several sections and shared by the two counter-rotating muon bunches. The accelerator requirements are driven by the need to preserve a maximum number of muons by taking advantage of time dilation. Therefore, maintaining a high accelerating voltage throughout the chain is essential, imposing superconducting RF cavities in the GV range. However, the high bunch intensity of up to $2.7\times 10^{12}$ particles per bunch and the 1.3 GHz TESLA cavity’s small aperture will result in induced voltages in the MV range.
In the muon collider, the induced voltage of the counter-rotating beams will additionally impact the cavity voltage.
This contribution presents the cavity voltage modulation and its impact on the beam loss and stability in the strong transient beam loading regime.

Speaker: Mr Leonard Thiele (European Organization for Nuclear Research, University of Rostock)

16:00 Beam loss scenarios for the SOLEIL II upgrade

SOLEIL II is an ambitious upgrade project that aims to reduce the horizontal emittance of the SOLEIL facility from 4 nm to 84 pm (to be further reduced to 50 pm by running with round beams). The SOLEIL II lattice will utilise a combination of permanent magnets and electro-magnetic corrector magnets. In the case of beam losses, it is of critical importance to localise the losses to certain shielded areas or dedicated collimators in order to prevent the risk of demagnetisation of the permanent magnets. The study and development of different beam loss scenarios will be presented.

Speaker: Sami Habet (Synchrotron soleil)

16:00 Beam loss study for Hefei Advanced Light Facility

The Hefei Advanced Light Facility (HALF) which is a green-field diffraction-limited storage ring has a relatively low beam lifetime and very low beam emittance. So it is important to study the beam loss for the HALF storage ring to protect the insertion devices and optimize the radiation shielding. In this paper, a simulation for beam loss from two main mechanisms, beam dump and Touschek scattering, are presented. And the collimation scheme is also briefly introduced.

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

16:00 Characterisation and mitigation of RF knockout

Beam stacking is a key advantage of Fixed Field alternating gradient Accelerators (FFAs) for high-intensity applications. During stacking, one beam is stored as a coasting beam at the extraction energy while another, incoming beam is accelerated. However, the beam loss mechanism termed RF knockout can occur during stacking and undermine gains in extracted beam current. The accelerating RF program of the incoming beam can cause cumulative displacements in the stored coasting beam and result in significant beam loss. To ensure that beam stacking is a viable technique to extract highest intensities from an FFA, methods to avoid the loss from RF knockout must be established. This study presents results from a series of experiments at the ISIS proton accelerator to characterise and, crucially, to mitigate RF knockout and ensure successful beam stacking with no loss.

Speaker: Carl Jolly (Science and Technology Facilities Council)

16:00 Commissioning a 1.5-m linac and its application in UCLA Mithra Laboratory

A 1.5-m linac is being installed at the hybrid gun’s beamline in UCLA Mithra Laboratory for the advanced accelerator research. A preliminary experiment by using a steering magnet showed the electron beam was accelerated from 4 MeV to greater than 30 MeV. A more precise measurement of the beam energy with a new spectrometer magnet is planned in early 2025 as well as the beam emittance. The electro-optic sampling (EOS) experiment is under design for a coarse single-shot bunch length measurement for tuning the beam, while interferometry of the coherent transition radiation (CTR) from a metal foil is ready for the precision measurement of the length for the compressed bunch. For the application of the beam, the generation of coherent cherenkov radiation (CCR) at sub-THz in a hollow dielectric tube is being prepared. The detailed designs and results will be discussed on the spot.

Speaker: Atsushi Fukasawa (University of California, Los Angeles)

16:00 Conceptual study of multi-turn injection for SIS100 as a long-term perspective

The SIS100 synchrotron, currently under construction as part of the FAIR project, is set to play a pivotal role in advancing high-intensity ion beam research. Reaching the FAIR design intensities for low charge-state heavy ions, e.g. the reference ion U28+ will, however, be challenging due to limitations of the existing SIS18 synchrotron serving as injector to SIS100. In the long-term, the integration of a new linear accelerator capable of delivering high-intensity ion beams at energies up to 200 MeV/u would open the possibility of direct multi-turn injection (MTI) into SIS100, bypassing the SIS18. This paper investigates the MTI process for U28+ beams, aiming to accumulate up to 5x1E11 particles per cycle with high efficiency and minimal particle losses on the electrostatic septum. We present a theoretical analysis of horizontal-plane MTI, outline achievable beam performance, and discuss system requirements. Additionally, the proposed layout and parameters of the MTI equipment are detailed.

Speaker: Youssef El Hayek (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Considerations of a round beam operation at PETRA IV

Round beam operation is considered for the planned ultra-low emittance storage ring PETRA IV at DESY, Hamburg. With a natural emittance of 20 pm rad, we evaluate and discuss the advantages and challenges of sharing the emittance between transversal planes. The effect on single and coupled bunch instability thresholds, intra-beam scattering rates and Touschek lifetime of this operation mode are presented.

Speaker: Edgar Cristopher Cortés García (Deutsches Elektronen-Synchrotron DESY)

16:00 Coupling of codes for modeling high-energy-density conditions in fourth generation light sources

As previously described*, high-intensity beams of ultra-bright light sources present new machine protection concerns by creating high-energy-density (HED) conditions in beam-intercepting components. Simulating these HED conditions required us to develop a method for coupling three codes for particle dynamics (elegant), particle-matter interaction (MARS/FLUKA), and hydrodynamics (FLASH). This paper discusses the recent advancements made toward this effort including the use of phase and temperature dependent thermal properties such as thermal conductivity and specific heat, transition from MARS to FLUKA, and improved liquid phase dynamics. For benchmarking purposes we compare simulation results with experimental data collected during the final run of the Advanced Photon Source (APS) ring as well as observations of collimator surface damage following the first user run of the upgraded machine. This methodology is also used to make predictions of collimator damage in future APS-Upgrade (APS-U) runs and to examine locations where synchrotron radiation may lead to HED conditions.

Speaker: Nathan Cook (RadiaSoft (United States))

16:00 Current status of conceptual horizontal splitter design for FFA@CEBAF energy Upgrade

Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF) is currently investigating the feasibility of upgrading its maximum operating energy using Fixed-Field Alternating-gradient (FFA) recirculating arcs to increase the total number of recirculations of the beam through the pair of LINACs. These FFA arcs will be composed of permanent magnets, with small Panofsky-style multipole correctors. In order to control the beam parameters through these FFA arcs, horizontal splitters must be used. The geometrical and physical constraints, as well as the beam matching requirements are very restrictive, complicating the design. This work will show the current status of the most mature design, which includes matching solutions, as well as options for extraction of the beam.

Speaker: Reza Kazimi (Thomas Jefferson National Accelerator Facility)

16:00 Dark current in LCLS-II: source characterization and start-to-end modeling

The RF photoinjector in LCLS-II produces several microamperes of dark current via field emission. While the vast majority of this dark current is collimated before reaching the first cryomodule, a small amount (typically less than 1 nA) is transported all the way to the beam switchyard (BSY) dump. In this contribution, we present the results of a start-to-end model of the transport of the dark current through the LCLS-II accelerator, including loss patterns under common machine tuning configurations and evolution of the dark current’s phase space distribution. Understanding the phase space distribution in the BSY will benefit future experiments on the Linac-to-End Station A (LESA) beamline, including searches for dark matter, by enhancing our ability to tune the LESA optics to properly transport the dark current to the experiment.

Speaker: Sean Littleton (SLAC National Accelerator Laboratory)

16:00 Demonstrating the feasibility of a double-crystal fixed-target experimental physics setup through the TWOCRYST project in the LHC

The TWOCRYST proof-of-principle experiment at the LHC is an initiative to demonstrate the feasibility of a double-crystal setup for fixed-target physics experiments. Such a setup could enable spin precession studies of charmed baryons in the TeV energy range in the HL-LHC era. Major milestones in this project have recently been achieved, including the successful construction and testing of critical components such as the 4~mm and 7~cm long bent silicon crystals required, a new combined fixed-target and crystal goniometer for accurate angular positioning, and two Roman pot stations equipped with advanced tracking detectors. This contribution summarizes the status of the hardware, the results from the first machine development studies to prepare for the measurements with the crystals in 2025, and a detailed plan for the beam tests with the full TWOCRYST setup.

Speaker: Pascal Hermes (European Organization for Nuclear Research)

16:00 Design and magnetic field measurement of type c nonlinear magnet

By designing a C-type nonlinear magnet, low emittance beam injection is realized on HALF.

Speaker: Wei Bo Hu (University of Science and Technology of China)

16:00 Design and optimization of water-cooling scheme for a 162.5 MHz three-gap rebuncher cavity

To realize the matching of RFQ and DTL, it is expected to place a three-gap rebuncher cavity with a frequency of 162.5 MHz in the MEBT section. The dynamics design parameters of the cavity have been determined, so this paper mainly focuses on the RF design and multi-physics field analysis of the cavity. Modeled in CST, the normal temperature CH-type structure is selected, in order to increase the Q value and reduce the power consumption of the cavity, the parameters such as the radius of the stems, the outer radius of the drift tube, and the length of the drift tube at both ends can be reasonably optimized. Determine the RF parameters and then carry out multi-physics analysis, the most important of which is how to reasonably arrange the water cooling layout so as to reduce the temperature rise of the cavity, in this paper, the water pipe in the end plates finally adopts the 'L' type distribution. After simulation, the deformation and frequency shift of the cavity are within the acceptable range.

Speaker: Meiyun Han (Peking University)

16:00 Design and simulation of an electron gun for electron linacs

The electron gun is a crucial component of various vacuum electronic devices, including electron accelerators and electron microscopes. Prior to fabrication, designing and optimizing its geometry is a critical step to ensure optimal performance. In this study, the design and simulation of an electron gun for a linear electron accelerator are presented. The influence of key parameters on the electron gun's performance is analyzed.

Speaker: reza panahi (Shahid Beheshti University)

16:00 Design of an isochronous FFAG from 3 to 150 MeV

This study presents the design of an isochronous FFAG accelerator in the energy range of 3 to 150 MeV. A numerical method for solving the isochronous field is introduced, ensuring constant orbital frequencies across the energy range. The dynamic aperture was evaluated, multi-particle simulations were conducted to assess the impact of space charge effects on beam stability at different beam intensities. Preliminary results demonstrate the feasibility of the design.

Speaker: Kai Zhou (Institute of High Energy Physics)

16:00 Design of the beam transport lines for Super Tau-Charm Facility

The Super Tau-Charm Facility (STCF) is an electron-position collider proposed in China. The injector of STCF provides high quality electron and position beams at an energy up to 2.5 GeV at a repetition rate of 30 Hz. The beam transport system is composed of the electron bypass transport line, the transport lines from positron Linac to Damping Ring and from Damping Ring to positron Linac, and the injection lines from Linac to the collider ring. The low emittance preservation for both beams as well as the complex composition raise challenges for beam dynamics. The design and simulation of the beam transport system is presented in this report.

Speakers: Jianhao Xu (University of Science and Technology of China), Xiaoyu Liu (University of Science and Technology of China)

16:00 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 focuses on the design of the muon production and transport systems for a Muon Cooling Demonstrator facility in the CERN TT7 tunnel. A new implementation based on the CTF3 building is also presented, offering improved layout flexibility and beam intensity. FLUKA simulations are used to optimize the target and magnetic horn geometries to maximize pion production and capture, assuming a 14 GeV proton beam from the Proton Synchrotron (PS). The transport line, designed to deliver 190 – 210 MeV/c muons into the cooling channel, consists of a short pion decay section, followed by a momentum-selecting chicane and a matching section. The chicane integrates collimation and phase-rotation systems for transverse and longitudinal tuning of the muon beam. Beam optics for the transport lattice are designed in MAD-X, with tracking studies performed using BDSIM.

Speaker: Rohan Kamath (Imperial College London)

16:00 Design update on the EIC electron storage ring

The Electron-Ion Collider (EIC) aims at a luminosity of 10^34 cm^-2 sec^-1. Its Electron Storage Ring (ESR), which will be installed in the existing RHIC tunnel, will store electron beams from 5 to 18 GeV with beam currents up to 2.5 A. The design of the ESR has matured substantially. We will report the design status, including beam dynamics and polarization aspects, value engineering attempts, and latest developments of the injection scheme driven by changes in the injector chain.

Speaker: Christoph Montag (Brookhaven National Laboratory)

16:00 Design, fabrication, and magnetic measurement of a prototype pulsed septum magnet for the Korea-4GSR project

We have designed three types of septa—thin septum, thick septum, and DC septum—for the Korea-4GSR project, a 4 GeV diffraction-limited storage ring incorporating a 200 MeV LINAC and booster synchrotron. The thin septum is an in-vacuum pulsed septum magnet, the thick septum is an out-vacuum pulsed septum magnet, and the DC septum is an out-vacuum DC magnet. This presentation focuses specifically on the prototype design, fabrication, and measurement of the thick septum. The thick septum is designed with a maximum length of 1.25 m, a peak magnetic field strength of 0.56 T, and a minimum orbit distance of 18.6 mm. For prototyping, the length was reduced to 0.6 m while maintaining the same magnetic field strength and orbit distance, enabling the evaluation of manufacturability and magnetic field measurement techniques. We present the results of the design, fabrication, and magnetic field measurements of the prototype thick septum.

Speaker: Garam Hahn (Pohang Accelerator Laboratory)

16:00 Development of a 500 MHz high power solid state power amplifier based on GaN transistors

The adoption of Solid State Power Amplifier (SSPA) is rapidly increasing in major accelerators worldwide, replacing tube amplifiers such as Klystron and IoT. This study aimed to develop a High-Power RF system for Multipurpose Synchrotron Radiation Accelerators and to design and implement a GaN transistor-based SSPA. Through this research, we verified control performance equivalent to that of a 150 kW SSPA and successfully developed a prototype of a 5 kW RF module. Experimental results confirmed that the GaN transistor-based SSPA provides high efficiency and stable performance in the 500 MHz band, and based on this, we established a performance assurance plan for the 150 kW SSPA. This study demonstrates that GaN devices can effectively replace LDMOS devices with similar performance and competitiveness in the RF applications operating in the 500 MHz frequency range, which has traditionally been dominated by LDMOS. These results have significant implications for enhancing the performance and efficiency of High-Power RF systems and are expected to greatly expand the potential applications of GaN-based SSPA in various scientific and industrial research fields.

Speaker: Hyojin Kim (Pohang Accelerator Laboratory)

16:00 Development of a high-gain optical amplifier for optical stochastic cooling

Optical stochastic cooling (OSC) is a recently demonstrated state-of-the-art method for beam cooling and control. The strength and utility of OSC can be greatly extended by the inclusion of a high-gain optical amplifier in the system. The amplifier is necessarily a bespoke system whose design and implementation are highly constrained by the OSC physics and system design. In this report, we discuss the unique considerations and performance requirements for the amplifier, review detailed simulations for the integrated system, and report on the current experimental measurements and status.

Speaker: Jonathan Jarvis (Fermi National Accelerator Laboratory)

16:00 Development of a pulsed magnet measurement bench using the stretched wire method

In the scope of the renewal of its injection systems, the ESRF-EBS has decided to implement a new scheme using Non-Linear Kickers (NLK) magnets. These pulsed octupole like magnets are extremely sensitive to any misalignment of the conductors carrying the currents resulting in a degraded magnetic field quality. It is then important to characterize precisely the transverse magnetic fields of these magnets to avoid any perturbation during the injection process. A new method to measure pulsed magnetic field is being developed at the ESRF-EBS readapting the classical method of the stretch wire bench for permanent magnet. This paper presents the advancement of this project and the first results.

Speaker: Antonin Sauret (European Synchrotron Radiation Facility)

16:00 Development of new ion beams at the CERN ion injector complex for future physics programmes

In an effort driven by the requests from different physics experiments at CERN, the CERN ion injector complex is looking to expand its capabilities by providing lighter-than-lead ion beams. Argon and xenon were delivered for NA61/SHINE physics in 2015 and 2017, with xenon also reaching the LHC in 2017. Oxygen is foreseen to be collided in the LHC in 2025, with magnesium, boron and krypton beams also being prepared. Before new ion species can be considered operational for experiments, the feasibility of producing and accelerating these beams throughout the accelerator complex has to be assessed.
This contribution presents an overview of the performance of the ion complex with recently tested magnesium ion beams, the latest results of the ongoing oxygen beam commissioning, and future plans concerning ion species that still need to be developed.

Speaker: Roderik Bruce (European Organization for Nuclear Research)

16:00 Direct MOGA optimization of touschek lifetime and dynamic aperture using fast touschek tracking

A large momentum acceptance (MA) in 4th generation storage ring light sources is paramount to obtaining a long Touschek lifetime. However, the calculation of MA typically requires computationally expensive tracking simulations thereby complicating, or even disabling, the direct optimization of Touschek lifetime using numerical optimization algorithms. Our recent development of Fast Touschek Tracking allows obtaining the MA two orders of magnitude faster than standard MA tracking, thereby enabling direct optimization of Touschek lifetime. We present an example of a Multi-Objective Genetic Algorithm (MOGA) optimization of both on-energy dynamic aperture and direct Touschek lifetime using Fast Touschek Tracking for a 4th generation storage ring.

Speaker: Jonas Kallestrup (Paul Scherrer Institute)

16:00 Dynamic aperture correction for Ring Electron Cooler

The Ring Electron Cooler is one option to provide cooling to the Electron Ion Collider’s 275 GeV proton bunches. Using traditional electron cooling this racetrack shaped storage ring uses one straight section to cool the protons and the other one to enhance the radiation damping of the electrons using 2.4 T wigglers. These sections comprise the majority of the ring and are connected by short arcs. Space for sextupoles and octupoles is made in short straight sections between the wigglers. The strong wigglers and limited space for correction magnets create challenges in finding a suitable dynamic aperture correction. In this paper, we outline the challenges present in rings of this type and present a correction scheme that meets the aperture requirements of the design.

Speaker: Jonathan Unger (Cornell University (CLASSE))

16:00 Dynamic aperture studies for the EIC electron storage ring

The electron-ion collider (EIC), under design at Brookhaven National Laboratory, will consist of two storage rings for collisions of polarized electron and hadron beams. Dynamic aperture (DA) of 10 sigma is required in the electron storage ring (ESR) for the design beam energies from 5 GeV to 18 GeV to ensure an adequate beam lifetime. The DA is limited by chromatic and error effects in a strong optics with a low-beta interaction region. We present results of dynamic aperture studies for the latest ESR lattice (v6.3), which include compensation of non-linear chromaticity, the impact of field imperfections in dipoles, and the effects of dipole orbit.

Speaker: Boris Podobedov (Brookhaven National Laboratory)

16:00 EIC 197 MHz crab cavity HOM damping and tolerance analysis

Crab cavities, operating at 197 MHz and 394 MHz respectively, will be used to compensate the loss of luminosity due to a 25 mrad crossing angle at the interaction point in the Electron Ion Collider (EIC). Both cavities are of the RF Dipole (RFD) type. To meet the stringent impedance requirements for beam stability and quality, the cavity design must incorporate strong Higher Order Mode (HOM) damping. A special type of HOM coupler has been developed (for both horizontal and vertical HOMs), which consisting of a waveguide stub that couples to the cavity and a waveguide-to-coaxial transition that extracts the HOM power to an external load. This design effectively damps HOMs up to a frequency of 2 GHz. Due to the wide range of frequencies that need to be damped, the damping of some of the HOMs may be sensitive to errors in the cavity and coupler geometry. Therefore, the tolerance of HOM damping with respect to cavity errors needs to be properly addressed in the mechanical design and fabrication process. In this paper, we will present the design of the HOM couplers and the damping tolerance analysis of the 197 MHz cavity.

Speaker: Zenghai Li (SLAC National Accelerator Laboratory)

16:00 Enhancing beam intensity in SIS18 by a two-plane multi-turn injection approach

The existing synchrotron SIS18 will serve as an injector for the FAIR (Facility for Antiproton and Ion Research) complex in booster mode operation. FAIR requires high-intensity beams, placing stringent demands on increasing beam currents in SIS18. Operational experience has shown that significantly increasing beam intensity in SIS18 necessitates both a higher current from UNILAC and improved injection efficiency into SIS18. Currently, injection into the SIS18 synchrotron is performed using conventional multi-turn injection (MTI) in the horizontal plane.
To significantly enhance beam intensity in SIS18, we propose implementing a two-plane multi-turn injection scheme. This method aims to boost beam intensity to the desired levels (e.g., uranium beams exceeding 1x1E11 per cycle), even within the current capabilities of UNILAC.
This paper discusses how MTI gain can be increased with high efficiency through a two-dimensional technique of painting Lissajous-like patterns in horizontal-vertical space using an inclined electrostatic septum. Simulation examples are presented, illustrating the characteristics of the beam created in SIS18 and the potential effects of space charge forces.

Speaker: Youssef El Hayek (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Exploring the null space of the chromaticity response matrix at the Diamond Light Source

Many different techniques have been investigated at Diamond for optimising sextupole strengths*. One method not previously studied is to exploit the null space of the chromaticity response matrix. By performing a singular value decomposition (SVD) of the chromaticity response matrix, combinations of sextupole strengths are identified which alter the nonlinear lattice whilst keeping the chromaticity unchanged. Applying these sextupole strength changes opens an avenue to improve the beam lifetime and the injection efficiency at fixed chromaticity, thereby preserving the instability thresholds from collective effects. The results of applying this technique are presented both for beam tracking simulations for the Diamond-II lattice, including machine errors, and for machine-based measurements on the present Diamond synchrotron.

Speaker: Neven Blaskovic Kraljevic (Diamond Light Source)

16:00 Feasibility studies for a new transfer line to a muon cooling demonstrator at CERN

In the context of ongoing research for a future muon collider, one of the primary challenges is the efficient production and cooling of muons. To address this, a proposal is being explored to construct a demonstrator at CERN for testing a cooling cell. This demonstrator would include a target and focusing system, a chicane around a dump, and a cooling channel. A potential site for this facility is the end of the existing TT7 tunnel, which was used as a neutrino facility in the early 1980s and is presently used for storage of radioactive waste. This paper outlines the initial design studies for the transfer line that will deliver 14 GeV protons from the Proton Synchrotron to the target. The design aims to minimize costs while meeting all geometric and optical requirements. The possibility of operating the line up to 20 GeV is also explored.

Speaker: Pablo Andreas Arrutia Sota (University of Oxford)

16:00 First options for an ESRF EBS upgrade lattice

A new lattice for the EBS is proposed as preliminary candidate for the next generation ESRF storage ring. This new optics would feature lower emittance, matched optics at all ID, transparency conditions for insertions and overall a net gain in brilliance coherence and flux. Due to the reduced dynamic aperture, on-axis injection with a low emittance beam would be a requirement in order to progress with these optics.

Speaker: Nicola Carmignani (European Synchrotron Radiation Facility)

16:00 Further progress with alternative optics for the Diamond-II storage ring upgrade

We report the progress made on alternative optics namely low beta and low emittance cases for the DIAMOND-II storage ring upgrade. The results of optimizations of both linear and nonlinear optics as well as impacts of insertion devices on lifetime and dynamic aperture and injection scenarios will be reported.

Speaker: Neven Blaskovic Kraljevic (Diamond Light Source)

16:00 High Luminosity LHC collimation system performance for different optics configurations

The High Luminosity Large Hadron Collider (HL-LHC) presents significant collimation challenges due to its high stored beam energy. An effective collimation system is critical for ensuring stable operation, protecting the superconducting magnets and minimizing background to the experiments. This paper examines the current baseline collimation configuration and potential changes to the collimation insertion optics to improve the performance in various areas, for both proton and heavy ion beam operation. The study encompasses on- and off-momentum beam loss simulations across various stages of the operational cycle. Collimation performance is assessed based on leakage to superconducting magnets, as well as losses on the tertiary collimators, to probe this source of induced background to the experimental detectors.

Speaker: Bjorn Lindstrom (European Organization for Nuclear Research)

16:00 Implementation and simulation of a rectilinear cooling channel in BDSIM

Muon colliders offer high-luminosity, multi-TeV collisions without significant synchrotron radiation but require further exploration of muon production, acceleration, cooling, and storage techniques. A proposed 6D cooling demonstrator aims to extend the MICE experiment's validation of transverse ionization cooling to also reduce longitudinal emittance, using bunched muon beams and incorporating RF cavities for reacceleration. The cooling lattice includes solenoids for tight focusing, dipoles for beam dispersion, and wedge absorbers for differential energy loss. This paper presents a complete implementation of cooling channels for BDSIM, a Geant4-based accelerator simulation tool, using appropriate analytic field models to account for fringe-field-dominated magnets. Components have been tested individually and validated against other tracking codes such as G4BeamLine. A tracking study leveraging this implementation is presented, simulating and optimizing a rectilinear cooling channel for the 6D cooling demonstrator. The analysis incorporates beam parameters from existing proton drivers, using outputs from targetry and capture system designs.

Speaker: Rohan Kamath (Imperial College London)

16:00 Improvement on beam-based alignment methods by reliability weighted average technique

Accurate determination of magnet centres seen by beams is the key to a successful commissioning of a particle accelerator storage ring. In this paper, several techniques to improve the beam-based alignment for a circular accelerator storage ring are introduced. Firstly, a formula to propagate the uncertainties from linear fitting is given. Secondly, a reliability weighted averaging technique based on uncertainties are applied to mitigate the impact of outliers. Thirdly, studies show that the accuracy and precision of quadrupole centre locations can be refined by using multiple corrector magnets in the process. Finally, to improve the efficiency when using multiple correctors, a monte-carlo technique is utilized. The resulting distributions of all BPM-to-Quad offset residuals derived from simulations are presented.

Speaker: Dr Hossein Ghasem (Diamond Light Source)

16:00 Increasing single-bunch intensity limit at ESRF-EBS with high coupling

Synchrotron radiation light sources normally operate at a low coupling between the transverse planes in order to achieve flat beams and produce high peak brilliance. Instead, operating at a high coupling has other advantages such as smaller emittance degradation due to intra-beam scattering, improved Touschek lifetime, and lower sensitivity to vibrations of the photon beam. Moreover, it has been suggested that a high coupling may enable achieving higher bunch currents thanks to sharing of the beam-induced wakefields between the transverse planes. We were able to take advantage of this effect to substantially increase the TMCI threshold at zero chromaticity and nearly double the single bunch current limit at high chromaticity at ESRF-EBS.

Speaker: Sergey Antipov (Deutsches Elektronen-Synchrotron DESY)

16:00 Introduction of key performance indicators for the GSI accelerator facility

The GSI Facility consists of several accelerators, offer-ing the distinctive capability to provide different ion beams with varying characteristics to a range of experi-ments simultaneously. In order to facilitate the monitor-ing of machine performance across diverse beam produc-tion chains and experiments, a Key Performance Indica-tor (KPI) metrics has been introduced. The CRYR-ING@ESR team has completed an initial KPI assessment of the ion storage ring and developed procedure to ana-lyse beam diagnostic data offline. Initial analysis has identified lacking information and features in the FAIR Archiving System (FAS) and data structures to support automated tracking of machine performance. This paper will present detailed definitions of KPIs to enable quanti-tative, beam-based accelerator performance measure-ment, an assessment of their implementation and an outline of future developments.

Speaker: Oksana Geithner (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Investigation on injection-related beam loss at SuperKEKB

The current achieved highest luminosity at SuperKEKB is only one-tenth of the design value, and beam injection is one of the most serious issues in achieving the target luminosity. Recent operations in both the HER and LER rings have shown insufficient injection efficiencies and detector backgrounds. The achieved injection efficiency falls short of the required level, sometimes leading to difficulties in injecting the beam at high current values. Following each injection, significant signals from particle losses are detected in several Belle II detector components, particularly the vertex detector, resulting in saturating the data acquisition with a dead time exceeding 10ms. The complexity of the injection, and critical factors like injected beam quality, beam lifetime, dynamic aperture, machine errors, nonlinearity, as well as the collimation system, makes the optimization challenging. Detailed injection simulations are essential to understand the issues of the injection and guide adjustments to maximize the injection efficiency and mitigate the injection background. This paper presents the findings of HER injection simulations and their experimental validation.

Speaker: Hiroshi Kaji (High Energy Accelerator Research Organization)

16:00 Light upgrade of the ESRF booster

The ESRF booster has been built more than 30 years ago as injector of the first ESRF storage ring and it is still used to inject in the EBS. Several components of the booster have been updated in the years and it is now operated off-energy and with emittance exchange at extraction, however the lattice has not been modified since the '90s. A project to reduce the equilibrium emittance and bunch length of the booster by exchanging 18 quadrupole magnets has been proposed. In this paper we present the beam dynamics studies in presence of errors and the expected gain in injection efficiency.

Speaker: Nicola Carmignani (European Synchrotron Radiation Facility)

16:00 Longitudinal hollow electron beam

The intra-beam scattering in high charge state intense heavy ion beams is a problem worth considering. With the help of controlling the longitudinal distribution of the ion beam, it may be possible to alleviate the ion beam loss and to improve the ion beam lifetime caused by intra-beam scattering. Unlike the traditional cooling process of direct current electron beams or longitudinal uniform distribution electron beams, a longitudinal hollow electron beam is used to cool heavy ion beams. Ions at the edge of the ion beam will receive stronger cooling, while ions at the center of the ion beam will receive weaker cooling, avoiding overcooling at the center of the ion beam. This paper discusses the generation, measurement, and related issues of longitudinal hollow electron beams. Corresponding solutions and suggestions have been proposed for the problems and challenges that may be encountered in the research. The cooling process of longitudinal hollow electron beams will be simulated and experimentally studied in the further, with the hope of obtaining beneficial effects.

Speaker: Xiaodong Yang (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Longitudinal impedance of septum for Hefei Advanced Light Facility

The Hefei Advanced Light Facility (HALF) is a vacuum ultraviolet (VUV) and X-ray diffraction-limited storage ring light source. It has a relatively large dynamic aperture, and an injection scheme with a nonlinear kicker (NLK) was considered for the HALF. This kind of magnet was designed with a small gap shield in the central area to gain a flat magnetic field. A complete prototype has also been produced and the measurement of magnetic field was done. In this paper, an improved structure of the nonlinear kicker is presented based on the previous one. Simulation of the longitudinal impedance has also been done and will be given later.

Speaker: Dr Wenbin Song (University of Science and Technology of China)

16:00 Magnet assembly of IVUE32 in-vacuum-APPLE II at BESSY II

At HZB / BESSY II the first in-vacuum APPLE II undu-lator is under construction. The design includes three magnet arrays for each of the four magnet rows for an efficient force compensation. The support and drive sys-tem has been delivered. Currently the magnets for the 10-period prototype are fabricated by Vacuumschmelze. Within the project IVUE32 a new soldering technique based on reactive foils has been developed in collabora-tion with Vacuumschmelze. The magnet structure of the IVUE32 undulator will employ the soldering technique aiming for enhanced assembly simplicity. Two new ex-perimental setups for the characterization of soldered subassemblies have been built for obtaining stress-strain curves and for lifetime (fatigue) tests. These instruments will be presented and measurements will be discussed.

Speaker: Johannes Bahrdt (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 Manufacturing, assembly and construction progress of the ALS-U project to create a soft x-ray diffraction limited light source

The ALS-U project, aimed at enhancing the Advanced Light Source’s capabilities, is currently in the manufacturing, assembly, and construction phases. The construction of the accumulator, a crucial component, is nearing completion, with commissioning expected towards next year. ALS-U promises to deliver diffraction-limited performance in the soft x-ray range by significantly reducing the horizontal emittance to approximately 70 pm rad. This achievement will result in a remarkable two orders of magnitude brightness increase for soft x-rays compared to the current ALS. The design incorporates a nine-bend achromat lattice, featuring reverse bending magnets and on-axis swap-out injection utilizing an accumulator ring. This optimized design is specifically tailored to generate intense beams of soft x-rays, which possess spectroscopic contrast, nanometer-scale resolution, and broad temporal sensitivity. This paper provides an overview of the project’s design features and offers an update on the progress made in manufacturing, assembly, and testing.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

16:00 MAX 4U: an upgrade of the MAX IV 3 GeV ring

The MAX IV 3 GeV storage ring in Lund, Sweden, was the first implementation of a multibend achromat (MBA) lattice fourth-generation light source. Since it started delivery of light in 2016, three succeeding MBA-based rings and variants have come on-line: ESRF-EBS, Sirius and APS-U. Several others are being planned, designed, built or commissioned. All of these capitalize on the MBA concept and expand it to push the brightness and coherence performance even further. In order to continue to offer the Swedish and international scientific communities competitive tools beyond the end of this decade, MAX IV Laboratory launched in 2024 the conceptual design of MAX 4U , an upgrade of its 3 GeV storage ring aiming at an emittance below 100 pmrad. This performance boost is to be achieved through a minimum-interference upgrade in which localized interventions in selected subsystems and components are carefully chosen to provide the maximum performance increase with minimum cost and, equally important, minimum dark time for the MAX IV user community. This contribution describes the accelerator physics and engineering aspects of the MAX 4U conceptual design and presents the latest developments.

Speaker: Eshraq Al-Dmour (MAX IV Laboratory)

16:00 Multi-objective optimisation of the Diamond-II storage ring optics

The design performance of the 3.5 GeV Diamond-II low-emittance electron storage ring has been studied as a function of the linear and nonlinear lattice tuning parameters. A Multi-Objective Genetic Algorithm (MOGA) has been implemented to optimise both the beam lifetime and the injection efficiency for off-axis injection. The simulations have been run on 5 machine error seeds, including misalignment and field strength errors, to obtain a solution which is robust against machine imperfections. The results of the optimisation are presented alongside a comparison of the baseline performance.

Speaker: Neven Blaskovic Kraljevic (Diamond Light Source)

16:00 Operational deployment of automatic angular alignment for LHC collimators

The Large Hadron Collider (LHC) features a collimation system that protects the machine against beam losses that may induce the loss of superconductivity in some exposed lattice magnets. Thus, optimal cleaning performance must be ensured at all times. The collimation system encompasses more than 100 collimators whose settings are organised in a well-defined transverse multi-stage hierarchy. A collimator alignment toolset has been developed over the years to automate the alignment of the system during beam commissioning. During alignment, the collimator jaws used to be kept parallel to the central beam orbit. However, further tightening of the collimation hierarchy to improve the β* reach is only possible if the collimator jaw angles are precisely adjusted to compensate for any mechanical or orbit tilts. Advanced alignment procedures have therefore been developed to compensate for these effects. The first operational deployment of jaw angle has been achieved in the 2024 run. The commissioning results leading to this milestone are reported in this paper, together with the optimisation of parallel jaw alignment and an overview of the operational architecture.

Speaker: Andrea Vella (University of Malta)

16:00 Operational deployment of high brightness LHC beams in the SPS

Following the LHC Injector Upgrade programme (LIU) there has been a gradual ramp-up of the intensity of LHC beams in the CERN Super Proton Synchrotron (SPS). This was initially hampered by vacuum issues in several critical components, such as RF cavities and kicker magnets, requiring extensive scrubbing campaigns to condition these components. This paper reviews the current status of the high brightness LHC beams in the SPS, including commissioning evolution, aspects related to beam stability and beam optimization and the current brightness reach. An assessment of the operational readiness of these beams for the High Luminosity LHC era is also given.

Speaker: Giulia Papotti (European Organization for Nuclear Research)

16:00 Optics design status for the muon collider rapid cycling synchrotrons

The baseline design for the high-energy complex of a muon collider consists of a chain of pulsed synchrotrons spanning an energy range from 63 GeV to the target collision energy of 5 TeV. This chain incorporates both normal and hybrid synchrotrons, featuring a combination of fixed-field superconducting magnets and pulsed normal-conducting magnets. Initial optics designs for the chain of synchrotrons have been completed, with optimization efforts focused on minimizing the aperture dimensions required for dipoles and quadrupoles. Preliminary tracking studies have also been performed to evaluate emittance preservation throughout the acceleration process.

Speaker: Elias Métral (European Organization for Nuclear Research)

16:00 Optimizations for enhancing performance of emittance exchange-based photoinjector

A recent simulation study demonstrated the potential to achieve high 4D-emittance using an emittance exchange (EEX) beamline integrated within a photoinjector. This EEX beamline enabled to achieve the final normalized longitudinal emittance of 0.44 micron, which corresponds to rms bunch length of 7micron and energy spread of 32keV. These results are noteworthy for a 60-MeV photoinjector comprising a gun, linac, and EEX beamline. However, the transverse emittance of approximately 0.6 micron remains a limitation for many applications. To address this, we have conducted computational studies to improve the performance of EEX photoinjector. We present the progress achieved thus far.

Speaker: MinKyu Seo (Korea University Sejong Campus)

16:00 Orbit correction for PERLE accelerator

PERLE (Powerful Energy Recovery LINAC for Experiment) is a high-power Energy Recovery LINAC (ERL) facility with 20 mA beam current and 500 MeV final energy, initially operating at 250 MeV, through three accelerating and three decelerating passes. Operating in the high-power regime of 10 MW brings challenges in beam steering and control. This work studies optics misalignments and their impact on the stored electron beam. In particular, transverse misalignments in quadrupole magnets are examined. The misalignment effect on the beam orbit identifies key locations for the Beam Position Monitors (BPM). Corrector magnets are then incorporated into the lattice to address the impact of these misalignments on the beam orbit. PERLE has horizontal and vertical dispersion sections, therefore it is important to apply correction in both planes. The BMAD code is employed to determine the optimal correction scheme and the necessary range of the correction strength.

Speaker: Julien Michaud (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

16:00 Overview of ESRF-EBS's four-year operation and strategy for further upgrade

The user operation of the Extremely Brilliant Source (EBS) since August 2020 has opened a new era of high energy fourth generation synchrotron radiation light sources. During the following four years of operation, the EBS accelerator has sustained user operation with high availability, reliability, and stability, and has continued to improve beam performance by reducing injection perturbations, increasing bunch/beam currents for different beam delivery modes, and consolidating the storage ring operation with a hot-swap power supply system, newly designed kicker ceramic chambers, etc. Sustainability has always been key to EBS operation and future upgrades. During user operation, measures on the RF system of the storage ring and HQPS operation have been implemented to save power consumption; in the near future, solid-state amplifiers and 4th harmonic RF system projects will ensure the sustainability of machine operation further. In addition, as a strategy for future upgrades of the EBS accelerator complex, injector upgrades are being considered, including the injection with a new linac, which can be further upgraded to inject full-energy beam into the storage ring.

Speaker: Qing Qin (European Synchrotron Radiation Facility)

16:00 Physics design progress of the HALF project

The Hefei Advanced Light Facility (HALF), a soft X-ray and VUV diffraction-limited storage ring light source, started construction in 2023. This paper describes the physics design progress of the HALF storage ring over the past year.

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

16:00 Physics-driven specifications for the EIC ESR magnet power supply ripple

To avoid unacceptable proton emittance growth via beam-beam interaction, the EIC electron storage ring (ESR) requires very stringent tolerances for beam position and size stability at the interaction point. These tolerances imply tight specifications for several accelerator systems, including magnet power supplies (PS). While the magnetic field ripple requirements are most stringent at the betatron frequency and harmonics, the main PS challenges occur below ~1 kHz, where the ripple attenuation due to the vacuum chamber is insufficient.
In the original ESR dipole powering scheme with ~20 families, the dipole PS current ripple specifications were found to be near or beyond the state-of-the-art. A recently adopted scheme with a single ESR main dipole PS relaxes these requirements to ~10 parts per million (ppm) rms, which is achievable. Additionally, the vacuum chambers of non-standard cross-sections required at some dipoles must be modified to match the field penetration time constant to that of the standard vacuum chamber.
The paper presents the physics reasoning and simulations behind the latest PS ripple specifications, ranging from 5 to 100 ppm rms, depending on the magnet type.

Speaker: Boris Podobedov (Brookhaven National Laboratory)

16:00 Plan for the KOMAC proton linac upgrade to 200 MeV

A 100-MeV proton linac has been operated for over 10 years at KOMAC and used for proton beam services. We are planning to upgrade the linac energy to 200-MeV. By increasing the linac beam energy, we expect the machine to be capable of serving wider application fields including space radiation tests of semiconductor devices and material tests by using high-energy neutrons generated by bombarding a proton beam to a solid target. For the energy upgrade, we consider the SDTL structure for the 200-MeV section. The structure of SDTL is relatively simple so we may reduce the risk and time of development. In addition, we can avoid complex cryogenic systems by choosing a normal conducting approach. For the beamline, two separate target rooms (one for proton, and the other for proton and neutron irradiation) are under design. Details of the planning activity for the KOMAC linac upgrade will be reported in this presentation.

Speaker: Han-Sung Kim (Korea Atomic Energy Research Institute)

16:00 Preliminary results from the CLEAR nonlinear plasma lens experiment

Plasma lensing provides compact focusing of electron beams, since they offer strong focusing fields (kT/m) in both planes simultaneously. This becomes particularly important for highly diverging beams with a large energy spread such as those typically originating from plasma accelerators. The lens presented here is a nonlinear active plasma lens, with a controlled focusing-strength variation purposely introduced in one transverse direction. This lens is a key element of a larger transport lattice, core of the ERC project SPARTA, which aims to provide a solution for achromatic transport between plasma-accelerator stages. We report on preliminary experimental results from the CLEAR facility at CERN, which aims to probe the magnetic field structure of the lens using an electron beam, in search of the desired nonlinearity, together with 2D plasma simulation results.

Speaker: Pierre Drobniak (Laboratoire de Physique des 2 Infinis Irène Joliot-Curie)

16:00 Preliminary results of crystal channelling optimisation in the LHC using reinforcement learning

The Large Hadron Collider (LHC) can operate with high intensity proton and heavy ion beams, both of which require a collimation system to ensure an efficient operation and to protect against damage to sensitive equipment along the ring. The crystal collimation scheme using bent silicon crystals as primary collimators was therefore introduced to improve the collimation efficiency for heavy ion-beams. The first operational deployment of crystal-assisted collimation was achieved in the 2023 Pb run. This demonstrated the required performance gain to safely handle high intensity ion beams, but undesired crystal rotation led to the loss of optimal performance during physics fills. The cause of this is thought to be mechanical deformation of the goniometer due to heating related to beam impedance effects. Hence, a conventional numerical optimiser was deployed to monitor and compensate for crystal angular errors based on a set of beam-loss monitors. The problem at hand, allows for the use of machine learning techniques to ensure continuous optimal channelling, minimising convergence time and eventually the optimization of crystals in multiple planes in parallel.

Speaker: Andrea Vella (University of Malta)

16:00 Preparing the future SPS fixed target beams for the SHiP experiment

A new high-intensity Beam Dump Facility (BDF), hosting the SHiP (Search of Hidden Particles) experiment, is set to begin operation in CERN’s North Area (NA) in Run 4. To meet its physics goals, SHiP aims at accumulating 4$\times$10$^{19}$ protons on target per year, which will require approximately 10$^6$ high intensity cycles from the SPS with $4.2\times10^{13}$ p$^+$ per cycle (as operationally used during the CNGS era) over a $1$ s spill length. To reduce the future supercycle load and thus minimize the impact on the other physics facilities (especially at the CERN PS complex delivering the beam to the SPS), a strategy involving higher intensity per spill but a smaller number of spills for SHiP was proposed. In this context, a series of studies have been initiated to explore the intensity limits of the North Area beams in the SPS. This contribution presents the initial results on the correction of the intensity dependent tune shift induced by the beam coupling impedance and the transverse optimizations required for operating at higher intensities.

Speaker: Giulia Papotti (European Organization for Nuclear Research)

16:00 Progress on beam dynamics studies for the ISRS isochronous ring spectrometer

A new lattice configuration is being developed for a compact,isochronous ring for the ISRS project, as an innovative spectrometer at HiE-ISOLDE. The design incorporates ten combined-function, canted cosine-theta (CCT) superconducting magnets, enabling the ring to fit within a constrained 5x5 meter hall space. This design presents significant challenges, particularly in accommodating the injection and extraction of a high beam rigidity beam, as the CCT magnets mechanical dimensions severely limit the space available for these subsystems. Using Bmad code simulations, the performance of beam injection and extraction, based on a high-field, superconducting septum and a fast magnetic kicker, is evaluated, along with the time-of-flight separation of various isotope ion products from selected nuclear reactions of interest.

Speaker: Eduardo Martínez López (Instituto de Física Corpuscular)

16:00 Reconstruction of the beamlines of the 1.7 MV tandem accelerator to address the users' demands

The KOMAC (Korea Multi-purpose Accelerator Complex)of the KAERI (Korea Atomic Energy Research Institute) has been operating 1.7 MV and 3 MV Tandem accelerators for many years. Recently, in the fields of cultural heritage research and semiconductor device development, there have been strong demands from users for precise composition analysis and large-area & uniform irradiation of proton beam using a 1.7 MV Tandem accelerator. In order to satisfy the needs of these special and important users, the entire beamlines are being rearranged and beamline characterizations are being performed. The external beam PIXE (Proton-Induced X-ray Emission) beamline is being constructed for precise element composition analysis of cultural heritage samples, and for large-area silicon wafer uniform irradiation, the beamline, which was previously capable of uniform irradiation of proton beams up to 6 inch wafers, will be improved to 8 inches. This presentation focuses on the construction of the external beam PIXE beamline for cultural heritage analysis and the results of element composition analysis experiments on cultural heritage samples.

Speaker: Kye-Ryung Kim (Korea Multi-purpose Accelerator Complex)

16:00 Science at the RIXS beamline at MAX IV Laboratory

Here I will showcase the advanced precision instrumentations involved at the Veritas beamline dedicated to high resolution soft X-ray resonant inelastic X-ray scattering (RIXS) experiments. Following this, I will unveil the unique science cases one can attempt here.

Speaker: Anirudha Ghosh (MAX IV Laboratory)

16:00 Simulated beam performance of the TWOCRYST proof of principle experiment at the LHC

TWOCRYST is a machine test designed to demonstrate the feasibility of an in-vacuum fixed-target experiment for the first direct measurement of the magnetic and electric dipole moments of short-lived charm baryons. This setup exploits crystal channeling using two bent crystals. The first one is similar to the existing crystals used in the LHC for beam collimation, deflecting the beam halo particles from the proton beam onto a target. The second one - a 7 cm silicon crystal - induces spin precession in the secondary particles produced in the target. 2D detectors in movable Roman pots will track the distribution of these channeled particles. A new silicon pixel detector and a fiber tracker (formerly used by the LHC ATLAS-ALFA experiment) are planned for installation in the LHC along with the two crystals in early 2025. Xsuite simulations have been performed to reproduce the multi-turn beam dynamics of the channeled beam halo and the particle distribution expected at the detectors. The LHC configurations required for the planned measurements have also been simulated, with the results used to specify the required detector performance in preparation for benchmarking against real data.

Speaker: Chiara Maccani (European Organization for Nuclear Research)

16:00 Simulation of bent crystal collimators in RCS using G4PyORBIT

Bent crystal collimators (BCC) are a promising technology for halo collimation in high-power synchrotrons. To investigate their performance, a BCC module has been integrated into G4PyORBIT, leveraging Geant4's precise modeling of crystal channeling and PyORBIT's beam dynamics simulation capabilities. This study applies the tool to the rapid cycling synchrotron (RCS) at the China Spallation Neutron Source (CSNS). Preliminary results demonstrate the module's ability to simulate beam halo interaction with crystal collimators, evaluate collimation efficiency, and predict beam loss reduction.

Speaker: Kai Zhou (Institute of High Energy Physics)

16:00 Simulation of machine-induced background to ALICE in the 2023 LHC ion run

During the 2023 ion run at the LHC, where crystal collimation was regularly adopted for the first time, strong background levels were observed at the Inner Tracking System (ITS) of the ALICE detector. Some of the readout chips became saturated, causing losses of angular acceptance. This background was mitigated using a dispersion knob in the beam optics, letting some residual background remain. Considering that the next upgrade of the ALICE ITS foresees a further reduction of the interaction chamber aperture, understanding the mechanisms leading to this background appears critical to envision appropriated mitigation solutions. Preliminary studies showed that this background was related to losses at the upstream tertiary collimator (TCT), impacted by 207Pb82+ ions issued from beam interaction with the crystals of the primary collimation stage. Based on FLUKA simulations, this paper investigates the propagation of the tertiary collimator showers towards the ALICE cavern.

Speaker: Volodymyr Rodin (European Organization for Nuclear Research)

16:00 Simulation of the ion profile monitors in the Brookhaven AGS

Ion profile monitors (IPMs) provide a non-destructive means of measuring the transverse beam size of a passing ion beam in a particle accelerator. The Alternating Gradient Synchrotron (AGS) at Brookhaven National Lab is equipped with two types of IPMs: ion-collecting and electron-collecting. While ion-collecting IPMs are susceptible to significant distortions in the measured beam size due to the space charge of the passing beam, electron-collecting IPMs are much less affected. However, in the AGS, electron-collecting IPMs can only be operated periodically to preserve sensor lifespan, leaving ion IPMs as the sole source of consistent, real-time beam size feedback during operation. In this work, WarpX simulations of IPM operation are used to characterize the measured beam size as a function of beam parameters and IPM operating conditions. These simulations are then compared against experimental data collected from both ion and electron IPMs in the AGS. The findings aim to refine correction factors, enabling more accurate beam size estimations from ion IPM measurements, ultimately improving beam diagnostics and operational efficiency.

Speakers: Christopher Hall (RadiaSoft (United States)), Jonathan Edelen (RadiaSoft (United States))

16:00 Simulation studies and design updates for the nuSTORM facility

The neutrinos from Stored Muons (nuSTORM) experiment aims to create neutrino beams through muon decay in a storage ring, targeting %-level precision in flux determination. With access to two neutrino flavors, it enables precise measurement of $\nu$-A cross sections and exhibits sensitivity to Beyond Standard Model (BSM) physics. With muons in the 1-6 GeV/c momentum range, it covers neutrino energy regimes relevant to experiments like DUNE and T2HK. Additionally, nuSTORM serves as a step towards a muon collider, a proof of concept for storage rings, and a testbed for beam monitoring and magnet technologies. The lattice structure consists of a pion transport line and a racetrack storage ring based on a hybrid FFA design, with conventional FODO cells in the production straight combined with FFA cells in the return straight and arcs. This paper provides an update on the nuSTORM design and simulation efforts. It covers horn and lattice optimizations for producing and storing low-energy muons, describes tracking studies of the lattice to guide event normalization and presents the latest simulated neutrino fluxes.

Speaker: Rohan Kamath (Imperial College London)

16:00 Simulations of bunch length reduction techniques in the SLS booster

Modern injection schemes for light sources seek to explore the full 6D phase space in order to find creative ways of top-up injection with minimal perturbation to the stored beam. The longitudinal injection scheme is considered for the SLS 2.0 storage ring and, hence, the longitudinal profile of the injected beam becomes highly relevant for the injection efficiency. We simulate possible ways of reducing the bunch length in the SLS booster synchrotron. The feasibility of increasing the total RF voltage by installing additional or different RF cavities is considered. Furthermore, we simulate the impact of pulsed- or oscillating RF voltages and phases in order to compress the beam longitudinally at the expense of an increased energy spread.

Speaker: Jonas Kallestrup (Paul Scherrer Institute)

16:00 Single electron storage at UVSOR-Ⅲ electron storage ring

We have started single electron storage experiments since 2021 at the UVSOR-Ⅲ storage ring with the aim of conducting fundamental research on electromagnetic radiation. At BL1U, which is a beamline dedicated to light source developments, we extracted undulator light in the UV wavelength range into the air and observed its intensity by a photomultiplier tube, as decreasing the electron beam intensity using a beam scraper. When the beam intensity became sufficiently small, we observed step-function-like intensity changes with a good SN ratio, each of which corresponded to a loss of one electron. Based on this technique, we confirmed the single electron storage. After establishing the technique, we conducted some experimental studies on undulator radiation from single electron. We will present the latest results at the conference.

Speaker: Yuya Asai (Hiroshima University)

16:00 Space charge limit for light sources

With the adoption of multi-bend achromat lattices and the aim for diffraction limit, the state-of-the-art light sources are approaching a point where their emittance becomes so small that the effects of space charge can no longer be ignored. Space charge produces a significant betatron tune spread that affects many aspects of beam dynamics: single particle dynamics to collective beam stability. But most importantly, space charge imposes a fundamental limit to the ultimate beam brightness that can be achieved in a synchrotron light source. We demonstrate that the only way to increase the beam brightness and therefore the photon brilliance further is to opt for a higher beam energy.

Speaker: Sergey Antipov (Deutsches Elektronen-Synchrotron DESY)

16:00 Start to end commissioning simulations for SOLEIL II storage ring

This paper presents comprehensive start-to-end commissioning simulations for the SOLEIL II storage ring upgrade, demonstrating the feasibility of achieving an ultra-low emittance of 84 pm-rad at 2.75 GeV. We detail a multi-step correction strategy addressing challenges posed by the dense magnet arrangement and limited number of BPMs and correctors. Our simulations encompass first turn trajectory correction, beam-based alignment (BBA), and Linear Optics from Closed Orbit (LOCO) techniques. Results demonstrate the robustness of the correction scheme in the presence of realistic errors, showing successful recovery of design emittance, suitable dynamic aperture, and expected beam lifetime. This work provides insights into an efficient commissioning strategy for SOLEIL II, supporting rapid commissioning and full performance restoration for user operations.

Speaker: Sami Habet (Synchrotron soleil)

16:00 Statistical uncertainty studies on various data analysis methods for Stretched Wire Alignment Technology used for the Scorpius Injector

This paper presents statistical uncertainty studies on data analysis methods employed for the alignment of induction voltage adder (IVA) cell magnets in the Scorpius Injector. The Stretched Wire Alignment Technique (SWAT) was utilized to precisely locate and align the magnetic axis of beamline solenoid magnets. A current pulse with duration of approximately 100 µs was propagated through a stretched wire, generating a traveling wave due to the transverse magnetic force acting on the wire. The resulting transverse displacements in both horizontal and vertical directions were measured as a function of time using laser micrometers. By systematically repositioning the wire relative to the mechanical center of the magnet, the true magnetic axis and its offsets from the mechanical center were determined based on the displacement amplitudes or the magnetic field magnitudes inferred from the wire’s motion. Statistical uncertainty analysis of various data analysis methods was conducted to evaluate the reliability of the estimated magnetic axis offsets. The results provide a robust range of offset estimates, ensuring accurate alignment of the IVA cell magnets within the injector system.

Speaker: Michael Bates (Sandia National Laboratories)

16:00 Status and performance of LumiBelle2 in the 2025 beam operation of SuperKEKB

LumiBelle2 is a fast luminosity monitor used for beam parameter tuning and feedback at the interaction point of SuperKEKB. It uses sCVD diamond detectors placed in both the electron and positron rings to measure the rates of single bremsstrahlung events. Luminosity signals are provided both for averaging all bunches and for each bunch crossing at 1 Hz. The averaged luminosity signal over all bunches is also provided at 1 kHz as input to a dithering feedback system used to maintain optimum overlap between the colliding beams in the horizontal plane. In 2025, new LGAD sensors will be tried as potential alternative to the sCVD diamond sensors. This paper will describe the overall status and performance of LumiBelle2 in the Autumn 2024 and Winter 2025 SuperKEK operation, as well as report on the tests with the new LGAD sensors.

Speaker: Meng Li (Chinese Academy of Sciences)

16:00 Status and perspectives of multi-terawatt long-wave infrared lasers for particle acceleration research

Recent years have seen growing interest within the laser particle acceleration community in laser sources operating at wavelengths substantially longer than the ~1 µm typical of present-day facilities. This renewed focus is fueled by recent advancements in powerful mid- and long-wave infrared (M/LWIR) laser sources. While fundamental advantages, such as the λ2-scaling of ponderomotive potential and the 1/λ2-scaling of critical plasma density, have long been recognized, the emergence of improved laser technologies has made their practical exploitation more accessible and compelling.
The backbone of a 5-TW 9.2-µm laser system at BNL ATF is a series of high-pressure CO2 amplifiers, where we have pioneered several novel techniques. These include the use of mixed-isotope active media, a solid-state frequency-conversion-based seed source, and the implementation of chirped-pulse amplification in a gas laser system for the first time. A recent breakthrough in this effort is the development of a reliable bulk-material post-compression scheme, which is now being prepared for full-scale deployment.
We report on the current status of our work and discuss the prospects for this field.

Speaker: Mikhail Polyanskiy (Brookhaven National Laboratory)

16:00 Status of the beam dynamics studies for the PERLE Energy Recovery Linac

PERLE (Powerful Energy Recovery Linac for Experiments) is a three-turn, high power Energy Recovery Linac under construction at IJCLab, France. It emerged from the design of the LHEC and FCC-eh and will serve as a hub for the validation of several technical choices and exploration of a broad range of accelerator phenomena in an unexplored operational power regime (up to 10 MW in its final version). Up to now, the final lattice design and phasing has been finalised. Current studies focus on non-linear effects and longitudinal dynamics. Also, the commissioning scheme is under developpement. We will present the status of the beam dynamics studies of the project, and highligth some of the ongoing studies

Speaker: Julien Michaud (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

16:00 Status of the storage ring and magnets of the SILA project

SILA (Synchrotron Laser) is a project of the National Research Center Kurchatov Institute (NRC KI) planned for the period 2022-2033. It is aimed at creating a 4th generation synchrotron radiation source and a free electron laser. The storage ring is divided into 40 periods, the perimeter (SR) is 1103 m, the electron energy is 6 GeV, the horizontal emittance is 70 pm∙rad. The free electron laser is divided into 4 branches, the fourth branch is 2-4 GeV, the first - third 6 GeV. Magnets with high field quality requirements were developed for the project: dipoles on permanent magnets: dipole with longitudinal gradient and small dipole, quadrupoles with medium (50 T/m) and high gradient (90 T/m), combined dipole-quadrupole magnets, sextupoles and octupoles. This report will present the status of magnet production, their characteristics obtained during measurements and calculations of dynamics taking into account the field maps of real magnets.

Speaker: Ilia Yurin (National Research Nuclear University)

16:00 Status of VEPP-5 injection complex

The VEPP-5 injection complex was put into operation as a source of electronic and positron beams for the VEPP-2000 and VEPP-4M colliders at the end of 2016. To date, an operating energy of 430 MeV and a positron accumulation rate of 3.5 nC/s have been achieved. Options for improving the complex for working with promising installations are being considered. The latest results and prospects of operation are presented.

Speaker: Fedor Emanov (Budker Institute of Nuclear Physics)

16:00 Study on high current laser ion source with an inner solenoid

Laser ion sources can produce a very high pulsed beam current, but still more than 90% of the beam is lost. In order to further increase the beam current of the laser ion source, this study installed a solenoid in the ion source target chamber and investigated the relationship between the solenoid and the generated beam current.

Speaker: Liang Lu (Sun Yat-sen University)

16:00 The correction of beam trajectory for low energy injector

High-brightness and high-average current electron sources with excellent beam quality hold significant potential for applications in fields such as ultrafast electron diffraction (UED), free-electron lasers (FELs), and energy recovery linacs (ERLs). However, when the electron beam is initially generated, it typically exhibits large energy spread, beam size, and relatively low energy. During beam transport, it is highly susceptible to stray magnetic fields, which can lead to angular and positional deviations as the beam passes through magnets or microwave acceleration structures, ultimately degrading beam quality. This article focuses on the recent progress in low-energy beam commissioning of the SHINE injector.

Speaker: Zipeng Liu (Shanghai Synchrotron Radiation Facility)

16:00 The Elettra 2.0 project status

After 31 years of serving the user community with excellent results, on July 2nd 2025 the removal of the Italian third generation synchrotron light source Elettra (www.elettra.eu) will start to be replaced by Elettra 2.0 a fourth-generation one. The project is in full development and, being a diffraction limited light source, Elettra 2.0 will provide ultra-high brilliance and coherence to the experiments while at the same time the machine is designed to provide very short pulses for time resolved experiments. The project status and its possibilities will be presented and discussed

Speaker: Emanuel Karantzoulis (Elettra-Sincrotrone Trieste S.C.p.A.)

16:00 The Korea-4GSR storage ring lattice design

We present the lattice design features and performance evaluation of the Korea-4GSR storage ring. This greenfield ring has a 4 GeV beam energy, an 800 m circumference, and 28 cells. A natural emittance of 62 pm is achieved through the implementation of four longitudinal-gradient bends and six reverse bends within the hybrid multi-bend achromat unit cell. The ring includes two high-beta straights, designed to be nearly transparent to the normal straights. Sextupole and octupole magnet strengths have been optimized to suppress major detuning parameters, enabling the ring to achieve a large dynamic aperture and momentum aperture. Commissioning simulations were performed to investigate the optics correction strategy for each commissioning stage and to estimate the performance of the ring under error conditions.

Speaker: Dr Jaehyun Kim (Pohang Accelerator Laboratory)

16:00 The Novosibirsk fourth-generation light source SKIF development status

SKIF (Russian acronym for Siberian Circular Photon Source) – fourth-generation light source under construction in Novosibirsk. Natural emittance (at zero beam current and absent betatron coupling) of the SKIF is 72 pm at 3 GeV beam energy and 476 m circumference. Only two families of sextupoles provide horizontal and vertical dynamic apertures of 12 mm and 3.5 mm, respectively, and energy acceptance more than 5%. The flexibility of the lattice allows the beta functions to be changed in center of straight sections in a wide range from 0.5 m to 16 m, which opens up additional experimental possibilities for users. The paper presents status of development the SKIF project.

Speaker: Grigory Baranov (Budker Institute of Nuclear Physics, Synchrotron Radiation Facility — Siberian Circular Photon Source «SKIF» Boreskov Institute of Catalysis)

16:00 The optical stochastic cooling program at Fermilab

Recently, Optical Stochastic Cooling (OSC) became the first demonstrated method for ultra-high-bandwidth stochastic cooling. The initial experiments at Fermilab’s IOTA ring explored the essential physics of the method and demonstrated cooling, heating and manipulation of beams and single particles. Having been validated in practice, with continued development, OSC carries the potential for dramatic advances in the state-of-the-art performance and flexibility for beam cooling and control. The ongoing program at Fermilab is now focused on the development of an OSC system that includes high-gain optical amplification, which promises a two-order-of-magnitude increase in the strength of the OSC force. Here we review the progress and plans for the amplified OSC program. This includes detailed lattice designs and tracking simulations for the various experimental configurations, designs and status for the various hardware systems, and near-term operational plans and use cases.

Speaker: Jonathan Jarvis (Fermi National Accelerator Laboratory)

16:00 The TWOCRYST fibre tracker: A detector to characterize precession crystals at the LHC

A fixed-target experiment using two bent crystals is proposed to study the magnetic and electric dipole moments of short-lived charm baryons with unprecedented precision in the LHC. This will be achieved exploiting crystal channeling into a first crystal to extract the beam halo and then into a 7 cm long silicon crystal capable of inducing a measurable spin precession to the particles of interest. TWOCRYST is a proof-of-principle machine test scheduled for 2025, to test this setup and address the feasibility of the final experiment under LHC beam conditions. One main goal is the study of the channeling efficiency in this long crystal at TeV energies, requiring a 2D detector in movable Roman pots. The TWOCRYST Fibre Tracker, coming from the LHC's ATLAS-ALFA experiment, is a high-precision tracking detector with ten layers of crossing scintillating fibers coupled to multi-anode photomultipliers, and read out using compact front-end electronics. Intense refurbishment work was required on to adapt the detector to the purposes of TWOCRYST. This contribution summarizes the tracker specifications as derived from beam dynamics simulations and the results of tests prior to its installation.

Speaker: Chiara Maccani (European Organization for Nuclear Research)

16:00 The Vaccaro stability diagram of scaling FFAs

Fixed Field Accelerators (FFAs) are a promising candidate for future high intensity machines such as ISIS-II. It follows that the largely unexplored topic of coherent transverse beam instabilities in these machines is of increasing importance. Transverse instabilities, such as head-tail, can be mitigated in synchrotrons by adjusting the chromaticity appropriately. However, in scaling FFAs, the chromaticity is fixed at zero by design. On the other hand, the relatively strong tune shift with amplitude caused by the nonlinear field of FFA magnets provides a source of Landau damping. Here we evaluate the resulting stability region in the complex tune shift plane comparing an analytical prediction based on the extracted detuning with amplitude with the results from numerical tracking simulations. Hence, the impedance threshold of FFAs can be established.

Speaker: David Kelliher (Science and Technology Facilities Council)

16:00 Toward the emission of photoelectrons from high field cryogenic radio frequency guns

The intrinsic emittance obtained from radio-frequency (RF) photoinjectors is notably reduced by increasing the launch field at the cathode. Moreover, cryogenic RF guns offer the possibility of producing stronger fields, due to the higher bulk conductivity, while lowering the mean transverse energy (MTE) of near-threshold photo electrons. Such devices thus constitute an ideal tool for driving low emittance electron applications like ultra fast electron diffraction (UED) and free electron lasers (FELs).
The CYBORG beamline at UCLA is a stepping stone facility meant to investigate the production of very low MTE photoelectrons in cryogenic RF guns. In this paper we report about the status of the beamline progress. Indeed, after an initial phase dedicated to the study of dark current emission in the high field cryo-RF gun, the facility is heading toward a second phase aimed at producing high brightness photoelectrons. In particular, we discuss the integration of the existing system with the UV laser and a loadlock for cathode exchange as well as the plan for the diagnostics envisioned for the upgraded version of our beamline.

Speaker: Fabio Bosco (University of California, Los Angeles)

16:00 Towards operational reality with laser assisted charge exchange

Laser-Assisted Charge Exchange (LACE) is being developed at the Spallation Neutron Source (SNS) as a potential replacement for injection foils, which are not expected to endure in the 10 MW beam power regime. Previous experimental demonstrations have achieved highly efficient charge exchange of H⁻ ions to protons for beam durations of up to microseconds. A refined method, capable of scaling to full millisecond duty cycles, has been experimentally validated and aligns with theoretical models. The current phase of development focuses on optimizing laser and beam parameters for LACE using a newly installed, flexible experimental setup in the High-Energy Beam Transport (HEBT) line at SNS. This setup takes advantage of the upgraded SNS beam energy of 1.3 GeV, offering greater flexibility in selecting laser wavelengths for the experiments. Simultaneously, efforts are underway to design a LACE ring injection system that fits within the spatial constraints of the existing SNS ring injection region. This presentation will provide an update on the progress of these developments.

Speaker: Sarah Cousineau (Oak Ridge National Laboratory)

16:00 Tune domain behavior of single magnet lattices

Single-sextupole and single-octupole lattices ``exhibit .. all the typical properties of more complicated mappings and dynamical issues'', including horizontal resonances of all orders $N$ with island tunes $Q_I$. In general both island tune response spectra and tune modulation drive spectra have multiple lines. Stable motion in transverse phase space is compromised when a pair of drive and response lines align. This vulnerability is illustrated by realistic examples from the Relativistic Heavy Ion Collider.

Speaker: Henry Lovelace III (Brookhaven National Laboratory)

16:00 Undulators for BESSY III

Helmholtz Zentrum Berlin is engaged in the conceptual design of the BESSY III facility. The BESSY III storage ring will be a fourth generation synchrotron light source with an emittance of about 100 pm rad and an energy of 2.5 GeV. It will be equipped with advanced undulators to provide users with tailor-made light. So far cryogenic permanent magnet undulators, hybrid planar undulators and a variety of APPLE II undulators - conventional (in-air) and in-vacuum are planned to meet user requirements in terms of spectral range, flux and polarisation. In this paper we give an overview of the planned undulators, discuss some of the design aspects and present their expected performance.

Speaker: Atoosa Meseck (Johannes Gutenberg University Mainz)

16:00 Update on the experiment at the Argonne Wakefield Accelerator to actively control the energy chirp of an electron beam with transverse deflecting cavities

A high electron current is often needed in modern electron accelerators. To achieve this, an energy chirp must be imposed on the bunch so the electrons will compress when they pass through a chicane. This energy chirp is usually imposed by accelerating the beam off-crest from the peak fields of RF cavities, which increases the total length and power requirements of the linear accelerator (linac). A novel concept called the Transverse Deflecting Cavity Based Chirper (TCBC) can be used to impose an energy chirp onto an electron beam, without the need for off-crest acceleration. The TCBC consists of 3 transverse deflecting cavities (TCAVs), which together impose an energy chirp while cancelling out the transverse deflection. An experiment is being developed to demonstrate this concept at the Argonne Wakefield Accelerator (AWA). To run the experiment at AWA, two new TCAVs are under construction, and will arrive at AWA in June 2025. Next the cavities will be cold tested and setup of the experiment will begin. We anticipate running the experiment in late 2025. Here we report on the progress of the experiment and show results from General Particle Tracer* simulations of the beamline.

Speaker: Quinn Marksteiner (Los Alamos National Laboratory)

16:00 User research at Brookhaven Accelerator Facilities Division

Brookhaven's Accelerator Facilities Division provides users with access to cutting-edge research tools, including the Accelerator Test Facility (ATF) and the Ultrafast Electron Diffraction (UED) facility. The ATF features an RF photocathode electron LINAC, a femtosecond Ti:Sa laser, and a high-peak-power LWIR laser, all capable of synchronized or independent operation. These tools enable advancements in beam manipulation, accelerator and laser technologies, and the study of low-plasma-density regimes for precise electron seeding into plasma cavities. This supports the development of low-emittance beams for compact laser wakefield accelerators (LWFAs), with applications in science and industry. The UED facility, equipped with an RF electron gun and Ti:Sa laser, facilitates dynamic studies of material structures and other low-energy electron beam research. Starting in 2025, access to these facilities will be available through the BeamNetUS program for academia, industry, and national labs. These unique research opportunities will be presented.

Speaker: Mikhail Polyanskiy (Brookhaven National Laboratory)

16:00 Vertical emittance control with a beam shaker for PETRA IV

As an option to control the vertical emittance a beam shaker will be implemented at the planned upgrade of the synchrotron light source at DESY, Hamburg. We evaluate the electron beam dynamics for a simple sine-wave and a noise band excitation and present the expected equilibrium vertical emittances.

Speaker: Edgar Cristopher Cortés García (Deutsches Elektronen-Synchrotron DESY)

16:00 X-ray beam position monitor with pixelated GaAs detectors for high-power synchrotron radiation beams

A novel soft X-ray BPM (sXBPM) for high-power beams of synchrotron undulator radiation has been developed through a joint effort by BNL/NSLS-II and Stony Brook University. In this approach, custom-made multi-pixel GaAs detector arrays are positioned in the outer portions of the X-ray beam, with beam position inferred from the pixel photocurrents. The first R&D device was installed in the 23-ID canted undulator beamline of NSLS-II, about 27 m downstream of the canted EPU source, and ahead of any beamline elements (i.e. in white beam). The device has demonstrated sub-micron positional resolution without interfering with user experiments, including the most sensitive ones exploiting the beam's coherent properties. Beyond positional measurements, the sXBPM effectively monitors the beam's cross-sectional shapes at the detector array locations. Due to movable detectors, the sXBPM can also capture complete 2D cross-sections of the X-ray beam when beam interception is permitted. This paper reviews the sXBPM design and highlights the latest experimental results, demonstrating why this approach is well-suited for XBPMs in future light sources with highly coherent X-ray beams.

Speaker: Boris Podobedov (Brookhaven National Laboratory)

16:00 Xcoll-BDSIM coupling for beam collimation

Xsuite is a comprehensive simulation toolkit for accelerator physics, with Xcoll serving as the dedicated module for collimation studies. These studies involve tracking particles through an accelerator and simulating their interactions with matter, taking into account non-linear elements and large betatron and off-momentum deviations. Particle-matter interactions can be modeled using an internal scattering model, Everest, or coupled to external codes. This paper presents the integration of Xcoll with the Geant4 libraries by utilizing the Beam Delivery Simulation (BDSIM) code. This coupling enables efficient tracking of diverse particle species through materials, along with realistic simulations of energy deposition and secondary particle production. The implementation is designed to be flexible, supporting the inclusion of detailed collimator geometries, beam-gas interactions, and crystal channeling effects.

Speaker: Bjorn Lindstrom (European Organization for Nuclear Research, John Adams Institute for Accelerator Science)

Tuesday 3 June

09:00 → 09:30 TUXD: Hadron Accelerators (Invited)

Convener: Hiroshi Imao (RIKEN Nishina Center)

09:00 Personnel and machine protection for high power accelerator commissioning, operations, and power ramp up

Safety is one of the main concerns in accelerator society. The key FRIB strategies and experience can be shared, leading to the successful FRIB operations with no safety-related incidents and meeting stringent standard in a university area.
Personnel protection and machine protection are key to high power frontier facilities like FRIB. For a facility built in the middle of university campus with heavy ion beam power being ramped up order of magnitude higher than the current record, stringent engineered and administrative controls and state-of-the-art technologies are needed to safeguard commissioning, operations, and upgrades.

Speaker: Masanori Ikegami (Facility for Rare Isotope Beams)

09:00 → 09:30 TUXN: Beam Dynamics and EM Fields (Invited)

Convener: Seunghwan Shin (Korea University Sejong Campus)

09:00 Elevating beam quality and stability in linear accelerators through high order mode analysis

The pursuit of optimal beam quality and stability in linear accelerators (Linacs) stands as a cornerstone of accelerator physics. However, the presence of High Order Modes (HOMs) within Linacs, particularly in the context of energy recovery (ERLs), presents formidable challenges to beam quality and stability. In response to this challenge, the development of the Compact HOMEN (High Order Mode Evolution based on Energy budget) model has emerged, providing precise prediction and analysis of HOM effects on beam dynamics within superconducting cavities. This model facilitates meticulous optimization strategies, guiding researchers towards unprecedented advancements in high-brightness accelerated electron beam technology. By comprehensively understanding and managing HOMs, Linacs can achieve enhanced performance and efficiency, crucial for a myriad of scientific and industrial applications.
Through this study, we underscore the constraints posed by high currents and high repetition rate to ensure an optimal energy recuperation. Our findings not only deepen the understanding of ERL facilities but also underscore their transformative potential in shaping the forefront of accelerator technology.

Speaker: Sanae Samsam (Istituto Nazionale di Fisica Nucleare)

09:30 → 10:30 TUAD:Hadron Accelerators (Contributed)

Convener: Hiroshi Imao (RIKEN Nishina Center)

09:30 Progress in LINAC beam commissioning for high-intensity operations for J-PARC power upgrades

The Japan Proton Accelerator Research Complex (J-PARC) has achieved stable 1 MW operation test on its neutron target and is advancing toward higher power levels of 1.5 MW to support high-power MR operations and a second target station. This progression presents challenges, including increased intra-beam stripping (IBSt) of H⁻ ions, chop leakage from higher beam currents and emittance, low-energy beam loss due to halo formation, frontend fluctuations affecting beam transmission, and RF phase and amplitude fluctuations. To address these issues, a redesigned lattice mitigates IBSt, a new MEBT1 improves chopping and collimation, and machine learning-based compensation schemes manage frontend and RF fluctuations. Additionally, longitudinal and transverse matching schemes enhance beam quality, validated through benchmarked longitudinal measurements. Results from studies at 50 mA and 60 mA beam currents demonstrate significant progress in overcoming these challenges.

Speaker: Yong Liu (High Energy Accelerator Research Organization)

09:50 Status of the proton linac for boron neutron capture therapy in the iBNCT project

Accelerator-based boron neutron capture therapy (BNCT) has been studied worldwide for a novel cancer therapy using neutrons generated by an accelerator system. The iBNCT (Ibaraki BNCT) project began in collaboration with KEK, the University of Tsukuba, Ibaraki Prefecture, and private companies in Japan. The iBNCT project aims to realize linac-based BNCT with a compact and low-activation accelerator system based on the design and experiences of the J-PARC linac. It consists of an H+ ECR ion source, a 3-MeV RFQ, an 8-MeV Alvarez-DTL, and a beryllium neutron-generation target. Since a high neutron flux is required for the BNCT treatment, an average beam current of more than 1 mA is necessary with the combination of the 8-MeV proton and the beryllium target. By improving the vacuum, cooling water and low-level RF system, stable operation was achieved with an average beam current of 2 mA. After completion of the non-clinical studies in parallel with neutron beam characteristic measurements, the iBNCT project has started a clinical study in January 2024. In this contribution, the present status together with the conducted upgrade and prospects of the iBNCT accelerator will be presented.

Speaker: Masaharu Sato (High Energy Accelerator Research Organization)

10:10 Injection into Resonance Islands

An Accelerator Physics Experiment (APEX) was conducted in the Relativistic Heavy Ion Collider (RHIC) to verify the formation, rotation, and size of resonance islands.The experiment provides lattice parameters to be used to facilitate an alternative method of transition crossing in the Hadron Storage Ring (HSR) of the Electron Ion Collider (EIC) project by producing a non-adiabatic kick to the off-axis beam within the island to displace the beam to the central closed orbit across transition. Proton beam was injected directly into an octupolar field driven stable resonance island in RHIC. This paper describes the procedures used to perform this Resonance Island Injection (RII) and discusses the experimental results.

Speaker: Henry Lovelace III (Brookhaven National Laboratory)

09:30 → 10:30 TUAN :Beam Dynamics and EM Fields (Contributed)

Convener: Seunghwan Shin (Korea University Sejong Campus)

09:30 A Study on Eddy Current Distribution in the Coating Layer of a Nonlinear Kicker Chamber

This study presents 2D approximated expressions for eddy currents in the Ti-coated layer of a nonlinear kicker and compares them with numerical simulations. Nonlinear kicker-based injection schemes have be-come popular in recent years and are used at several facilities. Eddy currents, which depend on both the applied magnetic field and the chamber’s geometry, can create unwanted field components. The proposed approximations offer a fast and practical way to esti-mate the effects of these eddy currents.

Speaker: Hao-Wen Luo (National Synchrotron Radiation Research Center)

09:50 No parametric instabilities in actual linear accelerators except the envelope instability

Our studies indicate that parametric instabilities except the envelope instability are unlikely to be observed in actual linear accelerators unless waterbag or KV distributions are generated. Furthermore our studies and previous literatures indicate the dominance of particle resonances over parametric instabilities in high-intensity linear accelerators. Any counter evidence has not been found yet. We propose a way to overcome the previous design rule to avoid the zero-current phase advance > 90° for the high-intensity linac.

Speaker: Dong-O Jeon (Institute for Basic Science)

10:10 Comprehensive study of Robinson instability in active and passive higher harmonic cavities for bunch lengthening

Higher harmonic cavities (HHCs) play a critical role in storage rings by extending the bunch length, thus mitigating beam instability and increasing the beam lifetime. This study investigates the influence of Robinson instability on the bunch lengthening performance for both active and passive HHCs. A detailed comparison is conducted to analyze the Robinson instability thresholds and the parameters of the HHCs* that govern the onset of instability. Simulation results and theoretical analysis are combined to provide guidelines for optimizing HHCs configurations to balance effective bunch lengthening with stability requirements. As illustrative examples, we consider an active normal-conducting HHC for Korea-4GSR , and a passive superconduting HHCs for PLS-II.

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

10:30 → 11:00 Coffee Break

11:00 → 11:30 TUYD:Novel Particle Sources and Acceleration Techniques (Invited)

Convener: Hongwei Zhao (Institute of Modern Physics, Chinese Academy of Sciences)

11:00 Record beam intensity productions of highly charged heavy ions by 28-45 GHz superconducting ECR ion sources at IMP

Next generation heavy ion accelerators such as HIAF (High Intensity heavy ion Accelerator Facility), FRIB (Facility for Rare Isotope Beams), SPIRAL2, and so on strongly require high intensity highly charged ion beams. The production of intense highly charged heavy ion beams such as U3n+ is a worldwide challenge for the community. ECR (Electron Cyclotron Resonance) ion source is the most powerful machine to produce intense highly charged heavy ion beams. Recently, with the better understanding of ECR ion source plasma behavior and ion source technology advancement, high intensity heavy ion beams such as >0.5 emA U35+ (CW), >0.1 emA U46+ (pulsed) have been produced with state-of-the-art 24-28 GHz ECR ion sources. To further improve beam intensity for higher charge state heavy ion beams, the world First fourth generation ECR ion source (named as FECR) with microwave frequency 45 GHz is being developed at IMP. After 8 years development, the first plasma has been made in May 2024. This talk will report the recent progress of record beam intensity productions. The first beam commissioning results of FECR will be also presented.

Speaker: Liangting Sun (Institute of Modern Physics, Chinese Academy of Sciences)

11:00 → 11:30 TUYN:Colliders and Related Accelerators (Invited)

Convener: Jie Wei (Facility for Rare Isotope Beams)

11:00 Electron-Ion Collider status

The Electron-Ion Collider (EIC), which is being designed by BNL, JLab and other partners, will be a particle accelerator that collides electrons with protons and nuclei to produce snapshots of those particles' internal structure. It will collide polarized high-energy electron beams with hadron beams in the center-of-mass energy range of 20-140 GeV. The electron beam, employed as a probe, will reveal the arrangement of the quarks and gluons that make up the protons and neutrons of nuclei. The EIC will allow us to study the "strong nuclear force", the role of gluons in the matter within and all around us, and the nature of particle spin. This talk will describe the Electron-Ion Collider design and construction at Brookhaven National Lab.

Speaker: Sergei Nagaitsev (Brookhaven National Laboratory)

11:30 → 12:30 TUBD:Novel Particle Sources and Acceleration Techniques(Contributed)

Convener: Hongwei Zhao (Institute of Modern Physics, Chinese Academy of Sciences)

11:30 Experimental generation of petawatt power, extreme electron beams in a particle accelerator

In this contribution we report on the experimental generation of high energy (10 GeV), ultra-short (fs-duration), ultra-high current (∼ 0.1 MA), petawatt peak power electron beams in a particle accelerator. These extreme beams enable the exploration of a new frontier of high intensity beam-light and beam-matter interactions broadly relevant across fields ranging from laboratory astrophysics to strong field quantum electrodynamics and ultra-fast quantum chemistry. We generate such high peak current beams using the controlled shaping of the electron energy profile with an external, spectrally-modulated, ps-duration infrared (IR) laser pulse. This experimental demonstration opens the door to on-the-fly customization of extreme beam current profiles for desired experiments and is poised to benefit a broad swathe of cross-cutting applications of relativistic electron beams.

Speaker: Claudio Emma (SLAC National Accelerator Laboratory)

11:50 Status of the CARIE high gradient photocathode test facility at Los Alamos National Laboratory

This talk will report on the status of commissioning of the Cathodes And Radio-frequency Interactions in Extremes (CARIE) C-band high gradient photoinjector test facility and other high-gradient C-band research activities at Los Alamos National Laboratory (LANL). The construction of CARIE began in October of 2022. CARIE is powered by a 50 MW 5.712 GHz Canon klystron and will house a high gradient copper RF photoinjector with a high quantum-efficiency cathode and produce an ultra-bright 250 pC electron beam accelerated to the energy of 7 MeV. The klystron was received, 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. The test RF injector is made of copper and does not have cathode plugs. It will be commissioned to validate operation of the CARIE facility in Spring of 2025. The second injector that will accommodate cathode plugs is in fabrication. The designs of the photoinjector and the beamline, and status of the high-power testing of the injector and other C-band components will be presented.

Speaker: Evgenya Simakov (Los Alamos National Laboratory)

12:10 Optimization of the Korea-4GSR storage ring for increasing the off-momentum dynamic aperture by analyzing resonance driving terms

The Korea-4GSR is a next-generation diffraction-limited light source designed to provide beam brightness up to 100 times greater than existing facilities. Chromatic aberrations from strong focusing fields in quadrupoles are corrected using sextupoles and octupoles. However, these sextupoles and octupoles introduce nonlinear effects, causing electrons to follow nonlinear trajectories, ultimately reducing beam lifetime. Consequently, these nonlinear elements negatively impact both the dynamic aperture and local momentum aperture. The limitations on local momentum aperture are primarily due to transverse nonlinear dynamics. Recent studies have shown that minimizing one-turn resonance driving terms, reducing their fluctuations, or controlling amplitude-dependent tune shifts (ADTS) can enhance both dynamic aperture and local momentum aperture in various storage ring configurations, including DBA, MBA, and hybrid-MBA lattices. Therefore, we aim to optimize resonance driving terms using a Multi-Objective Genetic Algorithm (MOGA) to expand on- and off-momentum dynamic apertures and improve beam lifetime by increasing local momentum aperture for the Korea-4GSR.

Speaker: Junha Kim (Pohang Accelerator Laboratory)

11:30 → 12:30 TUBN:Colliders and Related Accelerators (Contributed)

Convener: Jie Wei (Facility for Rare Isotope Beams)

11:30 The third long shutdown (LS3) of the CERN accelerator complex

TThe Large Hadron Collider (LHC) operation began in 2008. Its superconducting equipment requires a cool-down/warm-up cycle lasting several months to access some key elements such as superconducting magnets, making annual shutdowns impractical and obliged for a change in programmed stops paradigm. A new lifecycle management approach for programmed stops was therefore necessary. The large interventions were grouped and performed during long shutdowns (LSs). They include maintenance, consolidation and upgrades. LSs last about three years and are scheduled typically every six years. Since the LHC depends on its chain of preceding injectors, this approach was extended to the entire CERN accelerator complex. This paper briefly outlines the methodology used to plan, prepare and coordinate these LSs and presents the interventions and main upgrades planned for the upcoming LS3, scheduled to start mid-2026 for the LHC. The paper highlights various projects, aimed at improving safety, performance, and operational availability as well as implementing new technologies and providing new facilities for the particle physics community.

Speaker: Jean-Philippe Tock (European Organization for Nuclear Research)

11:50 RHIC polarized proton operation in Run24

The Relativistic Heavy Ion Collider (RHIC) Run 24 was 27 cryo weeks, operating with collisions at the STAR and sPHENIX detectors. The primary mode was polarized protons at 100 GeV, where there was 22 weeks of physics production. sPHENIX continued commissioning, becoming fully operational after 13 weeks and the addition of isobutane to their TPC gas mixture. STAR had a low luminosity run followed by twenty weeks of high luminosity and radially polarized beams. To reduce the beam-beam parameter and maximize the number of collisions within a small vertex region at sPHENIX, sPHENIX planned to operate with a crossing angle. For 8 weeks, collisions were only at sPHENIX until the beam-beam parameter was sufficiently low to support the additional collisions at STAR. A significant number of power dips earlier in the run greatly affected machine performance and reliability. At the maximum achieved performance, the luminosity was limited by four factors simultaneously: accelerating RF cavity intensity limit, intensity from the injectors, losses at rebucketing, and dynamic aperture. Despite these difficulties, sPHENIX and STAR were able to collect sufficient data commensurate with their goals.

Speaker: Kiel Hock (Brookhaven National Laboratory)

12:10 Exceeding high-luminosity LHC performance targets during the 2024 Pb-Pb ion run

We review the 2024 Pb-Pb ion run at the Large Hadron Collider (LHC), in terms of the operational experience, the problems encountered and the main results. This run was the second heavy-ion physics period of LHC Run 3 at 6.8 Z TeV. With only 18 days scheduled for physics data-taking, the key objective was to address the problems encountered in the 2023 Pb-Pb run and establish stable and efficient operation. Thanks to several mitigation measures, the 2023 limitations were overcome, significantly improving the machine availability. Together with substantially higher intensity, thanks to the excellent performance of the Pb ion injectors, this paved the way for a record-high performance in terms of average daily integrated luminosity with ion beams at the LHC.

Speaker: Roderik Bruce (European Organization for Nuclear Research)

12:30 → 14:00 Lunch

14:00 → 15:00 TUZD:Photon Sources and Electron Accelerators (Invited)

Convener: Toru Hara (RIKEN SPring-8 Center)

14:00 Toward realization of few-cycle free electron lasers: basic concept and its experimental demonstration

The shortening of the FEL pulse length is an important subject, and especially reducing the FEL pulse length down to a few-cycle duration is a great challenge. However, there exists a theoretical limit that disturbs the realization of few-cycle FELs, which is known as the slippage effect. Recently, the author proposed a novel idea to overcome this difficulty and experimentally demonstrated it*. This talk will review its fundamental mechanism and report the results of the demonstration experiments, together with perspectives of few-cycle attosecond pulses that become available with this concept.

Speaker: Dr Takashi Tanaka (RIKEN SPring-8 Center)

14:30 SPS-II project: Status update

Siam Photon Source II (SPS-II) is a 4th-generation synchrotron light source set to be constructed in Thailand, aimed at becoming a major synchrotron facility for Southeast Asia. It is designed with a 3 GeV low-emittance electron storage ring, featuring a DTBA lattice and a circumference of 327.6 meters. Recently, the design and machine parameters have been carefully revised, with a particular focus on optimizing vacuum performance and the main RF frequency to ensure beam stability and reliable operation.
In parallel with the design phase, significant progress has been made in developing key prototypes, including magnets, vacuum chambers, and girders, through collaboration with local Thai companies.

Speaker: Ms Porntip Sudmuang (Synchrotron Light Research Institute)

14:00 → 15:00 TUZN:Applications of Accelerators, and Engagement for Industry and Society (Invited): MC8

Convener: Jordi Marcos (ALBA Synchrotron (Spain))

14:00 Carbon ion therapy facility at Taipei Veterans General Hospital

Carbon ion therapy is gaining popularity due to its unique physical and radiobiological properties, such as a lower oxygen enhancement ratio (OER) than photon and proton therapy, indicating that efficacy is not limited by hypoxic tumor microenvironments. It also has a Its superior anticancer effect on hypoxic tumor cells, which are resistant to chemotherapy, radiotherapy, and immunotherapy. It is thus used to treat a wide range of cancers and increasingly being used to treat recurrent disease. TVGH is a national medical facility committed to protecting public health and upholding the highest medical standards. Given that cancer is Taiwan's leading cause of death, accounting for one-third of our hospitalized patients, we have spent decades researching and implementing cutting-edge anticancer treatments. As well as to complete the anticancer treatment spectrum in Taiwan, TVGH has established a carbon ion therapy facility of synchrotron accelerator type. Its construction began in 2019 and was completed in a record-breaking 15 months. After twenty months of equipment installation and verification, TVGH became the world's fourteenth and Taiwan’s only carbon ion therapy facility. Since the opening of this carbon ion therapy facility in May 2023, TVGH has treated nearly 200 patients, more than 90% of whom have pancreatic, prostate, liver, or lung cancer. Although TVGH has only been monitoring these patients for less than one year, numerous favorable results have been observed.

Speaker: Keng-Li Lan (Taipei Veterans General Hospital)

14:30 Compact hadron sources and linacs for societal applications

CERN Linac4 was formally approved in 2007 in the framework of the LHC Injector Upgrade Project with the purpose of removing the first intensity bottleneck in the chain of CERN LHC injectors. Linac4 was inaugurated in 2017 and became the sole proton injector at CERN in 2020. The experience and know-how built over a decade through the Linac4 project has subsequently been applied to accelerators for societal applications via the Medical Application Office and the Knowledge Transfer Group at CERN.
In this paper, we discuss the specific needs of accelerators for societal applications in terms of compactness, portability, and operability. We describe the specific beam dynamics that allow meeting those challenges and illustrate a few examples realized for medical applications and the analysis of fine art.

Speaker: Alessandra Lombardi (European Organization for Nuclear Research)

15:00 → 16:00 TUCD:Photon Sources and Electron Accelerators (Contributed)

Convener: Toru Hara (RIKEN SPring-8 Center)

15:00 Operational status and future project of the KEK Photon Factory

Two synchrotron radiation sources, the 2.5 GeV Photon Factory Storage Ring (PF ring) and the 6.5 GeV Photon Factory Advanced Ring (PF-AR), have been in stable operation at the High Energy Accelerator Research Organization (KEK) for over 40 years. This paper first describes the current operational status and recent developments at the Photon Factory. Next, a new concept of hybrid light source (PF-HLS) combining the advantages of a superconducting linac and a low-emittance storage ring is described. In the preliminary design, the beam energy can be switched between 2.5 GeV and 5.0 GeV. The storage ring will be constructed in a green field with a circumference of 750 m. Conceptual Design Report (CDR) has been published and updated since Jan/2024.

Speaker: Takashi Obina (High Energy Accelerator Research Organization)

15:20 Commissioning of the Advanced Photon Source upgrade - the first swap-out injection-based synchrotron light source

The Advanced Photon Source (APS) recently completed a transformative upgrade, replacing its 25-year-old storage ring with a state-of-the-art hybrid seven-bend achromat lattice with six additional reverse bends. The new design features a low natural emittance of 42 pm-rad, enabling productions of X-rays up to 500 times brighter than the original APS. The upgrade introduced a pioneering swap-out injection scheme, replacing entire depleted bunches rather than topping them up. This approach enables on-axis injection to accommodate for the reduced dynamic aperture resulting from strong focusing. The paper describes the commissioning process, operating experience with swap-out injection, and gives performance parameters of new systems such as the bunch-lengthening cavity.

Speaker: Vadim Sajaev (Argonne National Laboratory)

15:40 Evaluation method and countermeasures for the beam loss in fourth-generation light sources

Unlike the situation under the third-generation light sources, we will have to pay more attention to control electron beam loss under the fourth-generation ones. The main causes of the beam loss are (i) a beam dumped by switching off RF cavities and (ii) electrons lost by electron-electron scattering (the Touschek effect). Due to the low emittance, if the highly-dense dumped beam directly hits a chamber, that will induce a vacuum accident. Due to the short beam lifetime, the number of scattered electrons hitting insertion devices (IDs) increases, and demagnetization would severely shorten the ID lifetime to be less than 10 years. Here we evaluate and elucidate how a dumped beam and scattered electrons are lost in the storage ring. To investigate the process of Touschek loss, we developed an analytical method following Piwinski’s formulation and calculated the spatial and energy distributions along the ring. Taking SPring-8-II as an example, our calculation indicates that a beam shaker is effective to reduce beam power density, and the installation of vertical scrapers in the long straight sections and shielding materials in the IDs can prevent the component damage of the ring.

Speaker: Toshihiko Hiraiwa (RIKEN SPring-8 Center)

15:00 → 16:00 TUCN:Applications of Accelerators, and Engagement for Industry and Society (Contributed)

Convener: Jordi Marcos (ALBA Synchrotron (Spain))

15:00 Communicating environmental sustainability guidelines for large accelerator facilities

In the coming decades, numerous designs for new accelerator-based facilities, or potential upgrades to current facilities, have been proposed to support the next generation of scientific advancement. While these facilities have significant scientific, economic, and societal benefits, they also require considerable resources to operate effectively. Amid the ongoing climate crisis, these facilities face the challenge of balancing the need for increased scientific output, size, and/or power with the global need to reduce resource consumption. This challenge presents a unique opportunity to integrate innovative environmental impact reduction techniques into their design.
The presented living document offers high-level guidelines to enhance environmental sustainability across the planning, construction, operation, and decommissioning stages of large accelerator facilities. It consolidates various resources and highlights both existing and proposed practices to inspire more sustainable approaches.

Speaker: Dr Hannah Wakeling (John Adams Institute)

15:20 Engineering magnetic carbon nanotubes via swift heavy ion irradiation for spintronics and quantum technologies: XAS and RAMAN study

Carbon nanotubes (CNTs), known for their versatility as 2D materials, are key to advancing quantum technologies such as qubit fabrication and magnetic data storage. In this study, multi-walled carbon nanotubes (MWCNTs) doped with magnetic impurities (Fe and Co) were exposed to swift heavy ion (SHI) irradiation to explore induced structural modifications. SHI beams transfer energy to the carbon matrix via electronic energy loss and thermal spikes, causing Fe and Co ions to agglomerate within interstitial regions and defect sites of the CNT matrix. Structural changes were analyzed using high-resolution X-ray diffraction (HRXRD), Raman spectroscopy, and near-edge X-ray absorption fine structure (NEXAFS). HRXRD revealed peak dissolution, reduced crystallinity, and increased lattice strain, while Raman spectra showed partial annealing of damaged CNTs with disorder parameter reduction (FeCNT: 0.65→0.57; CoCNT: 0.55→0.52). NEXAFS confirmed non-destructive processing. These findings link ion fluence with defect engineering, paving the way for magnetic CNTs in spintronics and data storage.

Speaker: Priyal Singhal (Panjab University)

15:40 Commissioning of the South African Isotope Facility

The South African Isotope Facility (SAIF) is a radioisotope production facility based around a 70 MeV Cyclotron from IBA. SAIF was commissioned at the end of 2023 and commenced commercial isotope production in 2024. The facility is located in three vaults at iThemba LABS in Cape Town. The vault design, radiation modelling, and an overview of construction are presented. The designs and commissioning of the cyclotron, beam lines, wobbler magnet, dedicated target stations and target transport system are described and discussed, along with their current performance.

Speaker: Hugo Barnard (iThemba LABS)

16:00 → 18:00 Tuesday Poster Session: TUPB

16:00 A compact synchrotron for cancer therapy with helium ions

In the frame of the Next Ion Medical Machine Study (NIMMS) collaboration based at CERN, a compact synchrotron for radiotherapy with high-intensity helium beams is designed. Interest in helium ions is growing in the major treatment centers, since they provide superior accuracy compared to protons, thanks to their sharper lateral penumbra, and higher linear energy transfer. Their properties lie in-between protons and carbon ions, without the fragmentation problems of the latter. Moreover, their lower magnetic rigidity allows helium-ion accelerators to be more compact than the large carbon-ion machines.
The synchrotron design presented in this paper is based on normal-conducting dipole magnets at 1.65 Tesla and has a circumference of 35 meters. Optimized for helium ions, it can also accelerate protons, for treatment and particle radiography, and other species to smaller penetration depths. The design choices for the different systems are described taking into consideration the mechanical integration in a compact layout and operational flexibility. The technology readiness level is evaluated and R&D options to achieve higher performances and reduce energy consumption are identified.

Speaker: Maurizio Vretenar (European Organization for Nuclear Research)

16:00 Advances in accelerator-driven advanced nuclear energy system

Accelerator Driven Advanced Nuclear Energy System (ADANES) is to realize the transmutation of nuclear waste and the regeneration of nuclear fuel. ADANES can flexibly connect with the existing nuclear power system to achieve the goal of continuous and minimum waste discharge for the nuclear power system. A new sub-critical reactor concept is proposed as high power beam with one accelerator splitting into multiple beams to drive the sub-critical reactor, which is so called Multi-Beam Accelerator Driven System (MB-ADS). Based on the concept of MB-ADS, a fuel cycle system integrating transmutation and proliferation was developed, and efficient transmutation of minor actinide and spent fuel regeneration were realized at the same time. In this paper, the progress of the MB-ADS as well as the high reability accelerator and Multi-Beam beam line are presented.

Speaker: Yuan He (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Advancing heavy ion therapy via particle-in-cell simulations: insights into the interactions between an ion beam with realistic human body-like materials

Heavy ion therapy (HIT) is a transformative approach to cancer treatment offering precision to target tumors minimizing damage to surrounding normal tissue cells. This study explores the feasibility of applying the particle-in-cell (PIC) method to evaluate and optimize the clinical therapy of HIT. The PIC models ion beams & dynamics by tracking their motion with electromagnetic interaction and ion-fluid interactions at the nanoscale. PIC can accurately capture ion energy deposition patterns, ionization processes, and the generation of secondary particles that ion beams traverse in patient-specific body tissues and organs. The results reveal key insights into how ion beams interact with similarly constructed human tissue, influencing dose distribution, and therapeutic outcomes, involving key factors that may affect clinical procedures, such as specific tissue composition, and beam delivery parameters. The outcome would refine HIT protocols, supporting advancements in medical therapy, and enhancing surgical precision. This study also bridges computational modeling with clinical practice, providing actionable insights for improving HIT efficacy and safety.

Speaker: M.C. Lin (Hanyang University)

16:00 An RF ion source and accelerator for production of novel isotopes

This project describes the source for a neutron facility to produce 99Mo for Medical Diagnostics through the irradiation of natural
Molybdenum by means of a 14 MeV neutron source based on the Deuterium
Tritium fusion reaction.

Speaker: Rolland Johnson (MuPlus, Inc.)

16:00 Analysis of low-frequency disturbances (0.3 Hz) in TPS and TLS beam orbit feedback systems

The stability of electron beams in storage rings is vital for precise synchrotron radiation experiments. However, external vibrations, such as earthquakes, ocean waves, and human activities, often disrupt beam stability. This study analyzed low-frequency(~0.3Hz) disturbances in the beam orbit systems of the Taiwan Photon Source (TPS) and Taiwan Light Source (TLS). Using Fast Fourier Transform (FFT) and Dynamic Time Warping (DTW), we identified a strong correlation between these disturbances and ocean wave frequencies, with a similarity score of 0.12. Our findings confirm ocean waves as a major disturbance source and emphasize the need for advanced orbit control and vibration compensation to enhance beam stability.

16:00 Analysis of output waveforms in Taiwan Light Source (TLS) booster linac klystron modulator operation

This study focuses on the detailed analysis of signals generated by the newly implemented klystron modulator system in the Taiwan Light Source (TLS) booster linac, aiming to identify optimal operation points. Key parameters under investigation include the forward signals of the Low-Level RF (LLRF) SSA, klystron forward signals, and variations in electron bunches. Additionally, the relationship between energy gain and beam current recovery is explored to enhance system performance and operational efficiency.

Speaker: Szu-Jung Huang (National Synchrotron Radiation Research Center)

16:00 Application of bayesian optimization in magnetic horn design

Bayesian optimization is an effective method for designing complex systems with costly, non-analytic black box objective functions. It enables efficient exploration of the parameter space, making it well-suited for challenging problems in accelerator design which involve computationally intensive simulations such as FLUKA.
This study presents a framework to apply Bayesian optimization techniques to design the magnetic horn of Neutrinos from Stored Muons (nuSTORM) experiment for increased pion capture. The optimization process spans a wide range of operational energies, from 1 to 7 GeV, to address the physics reach of nuSTORM.
Batch sampling is enabled through specialized acquisition functions, allowing simulations to run in parallel across a computational cluster and significantly reducing the time needed to identify optimal target and horn configurations for the muon source. By leveraging the surrogate models generated through Bayesian optimization, horn configurations at different energies are systematically compared. This facilitates sensitivity studies to determine a minimal set of horn designs that efficiently cover the nuSTORM kinematic range.

Speaker: Rohan Kamath (Imperial College London)

16:00 Application of HAZOP and LOPA in the risk assessment of TPS LHe system at the NSRRC

The storage ring of Taiwan Photon Source (TPS) at the National Synchrotron Radiation Research Center (NSRRC) will utilize up to four cryogenic supercon-ducting radio frequency (SRF) cavities. These cavities require significant liquid helium cooling to maintain their superconducting state at approximately 4.5 K. Thus, the TPS Liquid Helium Manufacturing System (TPS LHe system) is crucial for providing the necessary cooling and stable pressure. We used Hazard and Oper-ability Studies (HAZOP) and a Layer of Protection Analysis (LOPA) to confirm the safety of the detailed design and the adequacy of risk control measures. The scope of this assessment encompassed the tanks, sys-tems, and pipelines associated with the TPS LHe sys-tem. We analyzed eight nodes corresponding to Piping and Instrumentation Diagrams (P&ID). This analysis resulted in HAZOP worksheets, LOPA worksheets, and a safety instrumented system integrity requirements summary (SIL Level List). Based on the evaluation results, we formulated improvement recommendations to address high-severity potential hazards by modifying internal designs or enhancing protective measures.

Speaker: Sheau-Ping Kao (National Synchrotron Radiation Research Center)

16:00 Base features of electron cooling systems for NICA collider

The project NICA (Nuclotron-based Ion Collider fAcility) aims to provide colliding beams for studying heavy ion collisions in the energy range 1-4.5 GeV/u. Obtaining maximum luminosity of the collider requires powerful longitudinal and transverse cooling at collision energy. That will be achieved with usage of both stochastic and electron cooling. The 2.5 MeV electron cooling system (ECS) includes two coolers, which cool ion beams in both rings simultaneously. The Budker Institute of Nuclear Physics (BINP SB RAS) already built and commissioned the electron cooling system for the NICA Booster with a maximum energy of 50 keV and now it develops the high voltage electron cooling system for the collider. This article describes the status of the ECS development.

Speaker: Vladimir Reva (Russian Academy of Sciences)

16:00 Beyond 1 MW operation of the J-PARC RCS

Beyond 1 MW operation of the J-PARC RCS
The 3-GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC) has already been achieved the designed 1 MW operation to the Material and Life Science Experimental Facility (MLF). However, to cope with the gradually getting faster operation cycle of the main ring synchrotron sharing more beam requires RCS to accelerate more than 1 MW beam per pulse for the MLF to ensure net 1 MW beam power at the MLF. Moreover, the beam sharing to the under designed 2nd MLF target facility has also to be considered. As a result, the next goal is to realize 1.5 MW beam power first and continue for 2 MW or even more. This will be done by injecting more particles in the RCS by increasing both peak current and pulse duration of the injection beam. Beam dynamics issues and possible scenarios to realize far beyond 1 MW in the RCS are presented.

Speaker: Kota Okabe (Japan Proton Accelerator Research Complex)

16:00 Building simple thermionic sources for eduction and low energy applications

To help master student understand the basic principles of a particle source, we have built a simple thermionic source with cathodes made of incandescent light bulb and other simple materials. We present here the main features of this source.

Speaker: Nicolas Delerue (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

16:00 Bunch filamentation within resonance islands

This paper presents turn-by-turn observations of internal and external filamentation within the Poincare contours of a fourth order resonance during an Accelerator Physics Experiment (APEX) in the Relativistic Heavy Ion Collider (RHIC). Beam position monitors measured the turn-by-turn evolution of the center-of-charge of the captured beam. The fraction of beam outside the island soon comes to contribute marginally to the center-of-charge signal. Simulation results are compared with experimental data.

Speaker: Henry Lovelace III (Brookhaven National Laboratory)

16:00 Bunch lengthening of the extraction beam using second harmonic in J-PARC RCS

The 3GeV Rapid-Cycling Synchrotron (RCS) at J-PARC supplies the beam to the Main Ring (MR). Under the current operating conditions, there is the longitudinal beam mismatch between RCS and MR. To improve the RCS-MR longitudinal matching, a method for the bunch lengthening of RCS at the extraction is proposed. The method is based on introducing a second harmonic RF voltage at beam extraction and placing the beam at the unstable fixed point. The considerations of the bunch lengthening in the RCS are described in this presentation. The focus is on optimizing the second harmonic RF voltage pattern. Demonstrations of introducing a second harmonic RF voltage are also discussed.

Speaker: Kyosuke Adachi (Japan Proton Accelerator Research Complex)

16:00 Calculation of the axial injection beam line of the U400R cyclotron

The Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research continues work on the reconstruction of the U400 cyclotron into a new U400R accelerator complex designed to produce accelerated ion beams with an atomic mass in the range of A = 4 ÷ 209 and an energy of 0.8 ÷ 25 MeV/nucleon. The intensity of accelerated ions will be about 2.5 μA particles for 48Ca ions. The axial injection system of the U400R cyclotron is a modernization of a similar system of the U400 cyclotron. The report presents the results of calculating the axial injection beam line of the cyclotron.

Speaker: Vladislav Lisov (Joint Institute for Nuclear Research)

16:00 CERN-MEDICIS: A unique facility for the production of radionuclides for medical research

The MEDICIS facility is a unique facility located at CERN, dedicated to the production of non-conventional radionuclides for research and development in imaging, diagnostics and radiation therapy, and based on offline mass separation. It exploits a classified area for handling of highly radioactive open sources, a dedicated isotope separator beam line, a target irradiation station at the 1.4 GeV Proton Synchroton Booster (PSB) and receives activated targets from external institutes during CERN Long Shut-Downs. After collection, the batch is prepared to be dispatched to a research center. Since its commissioning in December 2017, the facility has provided novel radionuclides such as Ba-128, Tb-155, Sm-153, Tm-165 Ra-224/Pb-212 and Ra-225/Ac-225 with high specific activity, some for the first time, to research institutes part of the collaboration. CERN-MEDICIS has advanced significantly to reach mature processes to translate into clinical application for the most promising radionuclides.

Speaker: Cyril Bernerd (European Organization for Nuclear Research)

16:00 CFD simulations of the target assembly at ORNL's second target station

The Second Target Station (STS) at Oak Ridge National Laboratory is designed to produce the world’s highest peak brightness neutron source using a 700 kW proton beam at 15 Hz, which interacts with solid rotating tungsten (W) target segments. The tungsten blocks are encapsulated in a 2-mm thick copper layer that retains the radioactive products generated during the spallation reaction, transfers heat to the cooling channels through its high thermal conductivity, and prevents direct contact between the water and tungsten to avoid erosion and corrosion. The copper cladding is further enclosed in a thick Inconel shroud that contains the cooling channels. This paper discusses the cooling channel design choices for the STS target segments, the target shaft, and the flow balance between them. It also explores the required flow rates under beam-off conditions to effectively remove decay heat. The results indicate that a flow rate of 0.1 GPM is sufficient to maintain the target block temperature below 92.5°C, satisfying the requirement of keeping the surface temperature below 150°C after 10 years of operation.

Speaker: Min-Tsung Kao (Oak Ridge National Laboratory)

16:00 Characterisation of transverse proton beam losses at the CERN Super Proton Synchrotron

The High-Luminosity LHC (HL-LHC) project foresees nearly doubling the design beam intensity of CERN's Large Hadron Collider (LHC). A particularly pressing issue is the observation of significant beam losses at the flat bottom in the Super Proton Synchrotron (SPS) that delivers these beams to the LHC. These losses arise from multiple factors: uncaptured beam losses that are generated during the bunch rotation in the Proton Synchrotron (PS) before the transfer to the SPS; large transient beam loading effects in the RF system during multi-turn SPS injections; and the diffusion of over-populated transverse tails, which reach aperture limitations. Dedicated beam measurements were carried out in the SPS as a first step towards untangling these losses. These studies aimed to disentangle the various loss mechanisms, with a focus on the halo population and potential correlations between transverse and off-momentum tails.

Speaker: Frederik Van der Veken (European Organization for Nuclear Research)

16:00 Conceptual design of the EIC electron storage ring beam abort mechanisms

Two types of beam abort mechanisms, namely, the External Abort System and the Internal Abort System for the Electron Ion Collider (EIC) Electron Storage Ring (ESR) are devised, designed and compared. Both mechanisms will be located in the Interaction region 2 (IR2). The External Abort System utilizes the ISABELLE Spectrometer tunnel to facilitate an extraction beamline and a beam dump, and the Internal Abort System generates a local orbit bump within the storage ring lattice to guide the electron beam into the beam dump. This article discusses the design of both systems, including the orbit bump design and ESR lattice modification, the resonant AC dipole design for the Internal Abort System, lattice simulation, the beam dump design and simulations using FLUKA, beampipe vacuum and impedance considerations near the beam dump.

Speaker: MINWOONG OH (Brookhaven National Laboratory)

16:00 Consideration for improving the longitudinal beam matching between RCS and MR at the J-PARC

The J-PARC 3 GeV Rapid-Cycling Synchrotron (RCS) delivers the high-intensity proton beam to the 30 GeV Main Ring (MR). The improvement of longitudinal beam matching between RCS and MR is desired to suppress the beam loss in the MR. A scenario to improve the longitudinal beam matching between RCS and MR is designed. For the RCS, the bunch lengthening scheme using the unstable fixed point generated by the second harmonic is considered. For the MR, the RF voltage pattern is adjusted to match the longitudinal beam emittance of the RCS. The details of the scenario for improving the longitudinal beam matching between RCS and MR and the results of beam simulation studies are reported.

Speaker: Dr Hidefumi Okita (Japan Atomic Energy Agency)

16:00 Density measurements and simulations on confined electron column in GL2000 Gabor-lens device

GL2000 Gabor-lens (GL) is a 2m long device built mainly for focusing and space charge compensation of hadron beams in energy ranges up to GeV. The electron cloud is initially produced by cold-cathode method with gradually ionisation of residual gas and is confined in a cylindrical trap much longer compared to previous constructed lenses. Density measurements were carried out at the test-stand in Goethe University in 2024. Outgoing stream of residual gas ions was detected within cylindrical spectrometer mounted on axis outside of the lens. Due to the dependency of the kinetic energy on starting potential, the on-axis potential and therefore confined average charge density can be derived. Measured densities were evaluated in a range of $10^{14}$-$10^{15} m^{-3}$. A large scale multi-particles Monte-Carlo-PIC (particle-in-cell) simulations with electrons and ions were carried out to understand collective phenomena in non-neutral plasma and to use the latter for linear and non-linear beam manipulation. Measurements and simulation results will be presented.

Speaker: Martin Droba (Goethe University Frankfurt)

16:00 Design and calculation of the RF system of the U400R cyclotron

Flerov Laboratory of Nuclear Reaction of Joint Institute for Nuclear Research carries out the works under creating of FLNR JINR Irradiation Facility based on the cyclotron U400R. The main systems of U400R are based on the U400 cyclotron. The objectives of this project are:
- to increase the intensity of accelerated 48Ca ion beams from 1.2 puA to 2 puA;
- to expand the energy range of accelerated ions from 2–20 MeV per unit mass to 0.8–25 MeV per unit mass;
- to extract ion using stripping foil and deflector;
- to reduce the energy spread in the beam to 3×10⁻³.
The results of calculating the parameters of the new RF-system are given in this work.

Speaker: Aleksey Zabanov (Joint Institute for Nuclear Research)

16:00 Design and optimization of a 3 GHz SCDTL for carbon ion acceleration in a medical injector

Linear accelerators offer key advantages over circular machines in hadron therapy, such as rapid energy modulation and reduced activation. In this work, we optimized a 3~GHz Side-Coupled Drift Tube Linac (SCDTL) in terms of energy efficiency and the maximum achievable acceleration voltage. Comparative analyses were performed with alternative optimized configurations in TE and TM modes for ions with $\beta = 0.15-0.40$. The optimized structures were subsequently implemented in beam dynamics simulations for the energy upgrade of a carbon ion injector to be installed at the Instituto de Física Corpuscular in Valencia, Spain, achieving full transmission.

Speaker: Eduardo Martínez López (Instituto de Física Corpuscular)

16:00 Design of a helium ion linear accelerator for astatine production

Astatine 211 is one of the most effective theragnostics isotopes for targeted alpha therapy of cancer. Connected to a carrier that links to cancer cells when injected in a patient, this powerful alpha emitter can selectively destroy cancerous cells.
Accelerator production of 211At requires sending beams of fully stripped helium ions (alpha particles) on a bismuth target at the energy of 7.1 Me/u. To obtain sufficient doses for hospital production of 211At, currents higher than what provided by cyclotrons are required. For this type of particle and intensities, cyclotrons are limited by the large amount of beam loss and activation in the extraction region, while linacs are virtually loss-free and much better suited for At production.
The design of an innovative linac for At production is presented, based on an alpha particle source of new design, a compact Radio Frequency Quadrupole, and a Quasi-Alvarez Drift Tube Linac (QA-DTL) going up to the final energy. Thanks to the QA-DTL low injection energy and compact design, the linac is only 10 meters in length. The overall design is presented, together with detailed RF and beam optics simulations.

Speaker: Maurizio Vretenar (European Organization for Nuclear Research)

16:00 Design study of HTS air-cored cyclotron coil system for medical RI production

The high current density of HTS material allows electromagnet to induce sufficiently strong magnetic field without relying on any iron core. This permits the design of air-cored cyclotron, where the absence of iron core brings the properties of light-weight and high field reproducibility, making it an ideal medical cyclotron to be installed inside hospitals. However, the cyclotron coil system need to induce highly accurate field while satisfying the engineering restriction from the HTS coil. Compact size, small fringe field and minimum fabrication cost are also desirable at the same time.
A HTS coil system of air-cored cyclotron is designed with the above restrictions taken into consideration. Multiple beam type accelerations that are required for medical RI production are simulated, in order to verify the usefulness of this design. In this work, the coil system design, the magnetic field and the HTS coil properties are presented. The feasibility of actual fabrication and in-hospital installation is discussed.

Speaker: Tsun Him Chong (Osaka University)

16:00 Development and Future Applications of the NARI 70 MeV Cyclotron

The National Atomic Research Institute (NARI) is developing a 70 MeV proton cyclotron, with construction set from 2023 to 2027. The cyclotron is designed to operate at proton energies from 28 to 70 MeV and a maximum current of 1000 micro-amperes. It will serve three main purposes: (1) medical isotope production, (2) proton irradiation testing, and (3) cyclotron-based neutron source development.
NARI aims to ensure a stable supply of radioisotopes for nuclear medicine, such as Tl-201, I-123, and Ga-67, while advancing the development of isotopes like Cu-67 and Mo-99. In addition to medical uses, the cyclotron will simulate space radiation environments for aerospace materials testing and radiation measurement standards.
The cyclotron will also support neutron-based technologies, benefiting nuclear physics, new materials, and industrial applications. Neutron research will occur in two phases: Phase I (2023–2026) will establish a thermal neutron target station for neutron diffraction studies, and Phase II (2027–2030) will develop a quasi-monoenergetic neutron (QMN) source for soft error rate testing in electronics and a high-resolution neutron imaging station.
Expected to be fully operational by 2028, the facility will include seven beamlines, two solid target stations, one gas target station, and specialized laboratories for proton, fast neutron, and thermal neutron research. The NARI 70 MeV cyclotron will support both routine isotope production and advanced scientific research.

Speakers: Jung Hua Yang (National Atomic Research Institute), Ting-Shien Duh (National Atomic Research Institute)

16:00 Development of a comprehensive Biosafety Management System for external user experiments at NSRRC

The National Synchrotron Radiation Research Cen-ter (NSRRC) operates the Taiwan Light Source (TLS) and Taiwan Photon Source (TPS) accelerators and approximately 40 end stations, about 10 of which are dedicated to biological research. Biologists from around the world utilize these facilities to investigate the structures and functions of biomolecules and cells, advancing the life sciences. Given the potential risks associated with biological experiments, particularly those involving biohazards, ongoing risk management is essential to ensure biosafety, as protocol failures often caused by human error or inadequate technique can increase the likelihood of exposure. This paper outlines the biosafety management framework at NSRRC, which supports users in sample classification, document submission, and risk identification to facili-tate a safe and efficient experimental review process.

Speaker: Sy-Yu Lin (National Synchrotron Radiation Research Center)

16:00 Development of a conduction cooling system for S-band niobium-tin superconducting RF cavities using cryocoolers

We have started research and development of a 4K niobium-tin superconducting RF (SRF) electron accelerator system for radioisotope (RI) production. The niobium-tin superconducting RF electron linac can be operated with the compact conduction cooling system without liquid helium and large-scale equipment. The cavity-cryocooler thermal link needs a careful design as its thermal conductance will control the temperatures of the cavity and the cryocooler. As the first step of our research, S-band Nb3Sn superconducting cavities and its conduction cooling system are developed, and their performance will be demonstrated. Beam acceleration experiments using those niobium-tin superconducting cavities are planned at the test accelerator at Tohoku University. The status of the niobium-tin superconducting cavity development will be reported at this conference.

Speaker: Ken-ichi Nanbu (Tohoku University)

16:00 Development of a friendly high-energy irradiation environment for future space developments

Effect assessments of high-energy radiations on materials and equipment are expected to become increasingly important in near future space developments. We initiated a project to construct an irradiation environment with high-energy radiations using the electron linear accelerator at Nihon University. The advantages of using this accelerator include the accelerations up to 100 MeV for high-energy and high-dose irradiations, its easy accessible location from Tokyo area. These advantages help many users including venture companies to use the irradiations with much less difficulties, that we consider as an important key to enhance future space developments.
The electron linear accelerator sends electron beams with a wide energy range to the FEL line by bending them 90 degrees with two 45-degree bending magnets. Irradiation tests are planned to be conducted using the radiation produced in this process. In this study, we present a simulation result on the acceleration process of the electron beam and the amount of radiation generated by the 45-degree bending magnets. We also show dosimeter measurements by the high-energy irradiations to be compared with the simulation results.

Speaker: Mizuki Kurata (Nihon University)

16:00 Development of a global tune geedback system for beam stability at the Taiwan Light Source

This paper introduces the development of a global tune feedback system at the Taiwan Light Source (TLS) to address tune variations resulting from changes in the gap and phase of insertion devices. The system utilizes two families of quadrupole magnets to sustain betatron tunes at their desired working points. Adjustment currents, essential for feedback control, are computed using a tune response matrix derived from the lattice model and processed through the singular value decomposition (SVD) algorithm. Real-time tune shift data, provided by a bunch-by-bunch feedback system, enables precise and efficient compensation. This integrated approach ensures robust beam stability and optimal performance under varying operational conditions.

Speaker: Szu-Jung Huang (National Synchrotron Radiation Research Center)

16:00 Development of a new cyclotron concept for medical application

Further development of a cyclotron design concept with advantages, such as energy efficiency and cost-effectiveness, is presented. The concept is optimized for non-superconducting cyclotrons. The main feature of the concept is the operation at high frequency (145 MHz) of the accelerating system.

Speaker: Oleg Karamyshev (Joint Institute for Nuclear Research)

16:00 Development of a water cooling system for solid-state power amplifiers at NSRRC

Since 2023, Solid-State Power Amplifiers (SSPAs) have been operational at the Taiwan Photon Source (TPS) of the National Synchrotron Radiation Research Center (NSRRC), Taiwan. The TPS employs two KEKB-type Superconducting Radio Frequency (SRF) cavities, with one cavity powered by a home-made 300 kW SSPA RF power system with a stored beam current of 500 mA. This study presents the design and implementation of the water cooling system for the SSPA RF station, addressing both system-level and module-level considerations.

Speaker: Shian Wen Chang (National Synchrotron Radiation Research Center)

16:00 Development of an automated learning program for optimizing kicker parameters in the Taiwan Light Source storage ring

This study presents the development of an automated learning program using Python to optimize the performance of the kicker parameters in the Taiwan Light Source (TLS) storage ring. The research focuses on enhancing storage ring current stability, improving injection current efficiency, and reducing the impact of environmental radiation in experimental areas. Through comprehensive analysis and discussion, the optimal operational parameters were determined, offering practical guidance for achieving efficient and stable storage ring operation.

Speaker: Szu-Jung Huang (National Synchrotron Radiation Research Center)

16:00 Development of an optical diagnostics system for ion sources

At iThemba LABS proton beams, extracted from an ion source, are pre-accelerated in an injector cyclotron and further accelerated in a K200 cyclotron and transported to various target stations used for radionuclide production. To gain a deeper understanding of the various processes occurring inside the plasma reservoir of the ion source and to support operational adjustments of the ion source, a novel optical emission diagnostics system is being developed in collaboration with the ISIS Facility of the Rutherford Appleton Laboratory. The proposed work builds on pioneering development of optical diagnostics of ion source plasmas and high-current beam-induced light emission at ISIS. The optical signals generated in the plasma and extraction region are collected and transported via an optical fibre to a diagnostics unit with multiple detectors suited for varying intensities and required temporal resolutions. Wavelengths of various emission lines are selected using bandpass filters. From this unit the signals are sent to a data acquisition system for processing. This contribution will present a preliminary design of the optical diagnostics system and the status of prototyping activities.

Speaker: Moenir Sakieldien (iThemba LABS)

16:00 Development of the beam separation test device to evaluate the electric field of non-destructive electrostatic septum

Slow beam the extraction in synchrotrons is utilized for various nuclear and particle physics experiments and radiology. A beam loss at a septum electrode induces equipment activation and damage. We have been developing a non-destructive electrostatic septum. This septum has multiple electrodes, and those are placed around the outside of the beam. Measuring the 2-D electric field distribution of this septum is important to evaluate the beam loss reduction due to this septum. We are developing the beam separation test device consists of a prototype septum, horizontal and vertical wire scanners and the electron gun installed on a movable stage fixed to a drive unit. This device measures the electric field by injecting an electron beam into the electric field and measuring the bending angle of the beam orbit. Since the width of the electron beam determines the resolution of the measurement data, we developed an additional lens system that can transport the beam 1.5 m with a width of 1 mm. We used a square chamber for the 2-D measurement system. A permalloy magnetic shield is installed inside the chamber and reduces the external magnetic field from 50 $\mu$T to less than 1.5 $\mu$T.

Speaker: Shota Nagayama (Tohoku University)

16:00 Development of the diagnostic and transport beamline for the muon linac low-velocity section

At the Japan Proton Accelerator Research Complex (J-PARC), low-emittance muon beams with a linear accelerator (linac) are proposed as a new approach to precisely measure the anomalous magnetic moment and electric dipole moment of the muon. Low-emittance muon beams can also be employed as new probes for non-destructive imaging techniques to see through structures. In the low-velocity section of the muon linac, a radio-frequency quadrupole linac (RFQ) and an interdigital H-mode drift tube linac (IH-DTL) are used to accelerate muons to β = v/c =0.08 and 0.28, respectively, at an operating frequency of 324 MHz. To reduce construction costs, the IH-DTL employs the alternating phase focusing (APF) method, which uses the transverse focusing force derived from the RF electric field. Because the APF method limits the transverse and longitudinal acceptances simultaneously, careful beam diagnostics and commissioning are essential to suppress the emittance growth derived from beam mismatches. In this paper, the results of the tracking simulation and the development status of the diagnostic and transport beamlines in the low-velocity section are described.

Speaker: Masashi Otani (High Energy Accelerator Research Organization)

16:00 Dose calculations for warm quadrupoles in the LHC off-momentum cleaning insertion

Interaction Region 3 (IR3) of the Large Hadron Collider (LHC) houses the off-momentum collimation system, designed to remove particles with significant energy deviations. The interaction of the beam with this multi-stage collimation system generates particle showers that impact various elements, including quadrupole magnets in the straight section. Radiation exposure to magnet coils and spacers raises concerns about potential damage. The upcoming High-Luminosity (HL) LHC upgrade will significantly increase radiation doses, necessitating further assessments. While shielding inserts were added to the quadrupoles during a previous shutdown, further shielding may be required, prompting dose predictions through the HL-LHC era in the 2040s. This paper presents FLUKA simulations where the off-momentum proton and heavy ion losses in LHC Run 2 (2014-2018) and Run 3 (2022-2026) is estimated from Beam Loss Monitors. These estimates serve as normalization factor for calculating the dose deposited in the quadrupoles. These results are then extrapolated to HL-LHC operational parameters, offering unprecedented insight into the future IR3 radiation environment

Speaker: Volodymyr Rodin (European Organization for Nuclear Research)

16:00 Effects of beam plane correlation on injection efficiency

The effectiveness and efficiency of a beam injection scheme is crucial
to achieve high beam intensities while minimizing possible beam losses.
The classical method for injecting from a linac to a synchrotron is
the multi-turn injection. In this scheme the quality of the injected
beam as well as of the injection scheme depends on factors as beam
emittance, type of local bump ramp, chromaticity, dispersion and beam
intensity. This approach relies on the decorrelation between the
planes of the injected beams. However, investigations on the beam
coming from the linac have suggested the possibility that a beam
correlation may exist*. We present here an investigation of the effect
of a correlated beam on the efficiency of the multi-turn injection for
several degrees of correlation.

Speaker: Annemarie Lauterbach (Goethe University Frankfurt)

16:00 Electron beam irradiation and dosimetry system at KAERI

KAERI (Korea Atomic Energy Research Institute) has been operating an electron irradiation facility for electron beam application research since 2018. This facility is used for a variety of purposes, from material improvement to the development of Large composite-based products such as wind turbine blades, using electron beams. In order to support this multipurpose electron beam utilization, in addition to the electron accelerator, we have also built and operated a dose measurement system, electron beam experiment device, and automation equipment. This paper describes the operation status and results of electron beam irradiation facility, including electron beam irradiation system and dose measurement systems.

Speaker: Hui Su Kim (Korea Atomic Energy Research Institute)

16:00 ESSnuSB target test facility

The ESSnuSBplus target station will consist of one target-horn system operating under an intense proton beam of 1.25 MW power, derived from the nominal 5 MW proton beam at 14 Hz frequency from the European Spallation Source (ESS) linac. The ESSnuSBplus target features a packed bed of titanium (Ti) spheres cooled with pressurized helium gas to withstand the substantial power deposition expected in the target bulk. The ESSnuSB Target Test Facility (ETTF) will be located in the Mechanical Measurements Lab (MML) at ESS. The ETTF setup is designed to investigate various aspects of cooling the Ti spheres with pressurized helium. Due to the granular structure of the target bulk, numerical CFD modeling of the thermodynamic behavior of the cooling system and target pellets is highly complex and necessitates experimental validation. The primary objective of this R&D setup is to address the challenges in simulating the mechanical and thermodynamic behavior of the target cooling system.
Current status of the commissioning of the R&D prototype target system and the results of the aforementioned studies will be presented.

Speaker: Tamer Tolba (Universität Hamburg)

16:00 Evaluating the feasibility of TPS high heat load components for high-current operation using TMSI

The Taiwan Photon Source (TPS) currently operates at 500 mA beam current, with future evaluations targeting 800 mA to assess the feasibility of high-intensity operation. This imposes significant thermal and mechanical challenges on high heat load (HHL) components, such as premasks, fixed masks, slits, and absorbers, in the storage ring and front end. To systematically evaluate the severity of existing designs, we developed the Thermal-Mechanical Severity Index (TMSI), which quantifies combined thermal and mechanical stresses, enabling targeted comparisons within component categories. Finite Element Analysis (FEA) simulations using ANSYS were conducted to provide detailed thermal and thermo-mechanical results, supporting the validation of the TMSI framework. TMSI streamlines component assessment, reduces the need for exhaustive case studies, and facilitates prioritization of redesigns to ensure the reliability and longevity of HHL components. This methodology represents a practical and efficient approach to advancing TPS design and operation for next-generation synchrotron performance.

Speaker: I-Ching Sheng (National Synchrotron Radiation Research Center)

16:00 Evaluation of effective parameters in the selection of industrial electron accelerator for industrial wastewater treatment

In this paper, the energy and power parameters of the electron beam have been investigated in the range of 0.5 to 3 MeV and 20 to 50 KW, respectively, with the aim of determining the optimal operating conditions to achieve maximum efficiency of industrial wastewater treatment. The findings quantitatively show the effect between the beam power, accelerator efficiency, treatment volume at different doses, and economic evaluation.

Speaker: Zahra Safahani (Amirkabir University of Technology)

16:00 Exploring the potential of accelerator-based neutron generators in modern research

The Institute for Plasma Research in India set up an accelerator-based 14 MeV neutron generator utilizing Electron Cyclotron Resonance Ion Source technology. This advanced generator can produce 1012 neutrons per second in continuous and pulse modes. By directing deuterons at a TiT target, it generates fast neutrons that are essential for various applications such as fusion experiments, electronics testing, feasibility studies of medical isotope production, neutron radiography, etc.
Various independent neutron diagnostics such as diamond detectors, proportional counters, and foil activation have been installed in the Neutron Generator. These techniques provide precise measurements of neutron flux, which are cross-checked with the associated alpha diagnostic technique to ensure accuracy.
Additionally, lab-scale experiments at IPR have explored neutron irradiation for medical radioisotope production and radiation-induced damage in electronic components. This paper highlights the significance of precise measurement techniques and demonstrates the critical role of neutron generators in advancing research and practical applications, from medical isotopes to fusion neutronics studies.

Speaker: Rajesh Kumar (Institute for Plasma Research)

16:00 First results of the new eddy current septum for the CERN PS fast extraction

CERN has developed a new fast pulsed septum magnet to replace the aging PS proton extraction septum. The aim is to increase the refurbishment intervals of the magnet and to phase out the old power converter, while allowing energy savings during operation.

The new system includes a novel under vacuum eddy current septum magnet, a new third-harmonic fast pulse generator and dedicated control system with post pulse fault analysis for achieving the required flat top precision.

This paper will briefly describe the system development and focus on the lessons learned from its construction and report the results of the testing phase.

Speaker: Laurent Ducimetière (European Organization for Nuclear Research)

16:00 Focusing high-energy electron beams with silicon crystals for radiotherapy applications

Radiotherapy can be performed using a high-energy electron beam (several hundred MeV) tightly focused on the tumor area, offering a relatively simple approach to beam generation and handling while achieving a favorable energy deposition profile in tissue-like materials. However, traditional beam focusing relies on quadrupole magnets, which add complexity and pose significant engineering challenges to the beam delivery system. Using the Geant4 simulation toolkit, we conducted a feasibility study of an alternative approach where beam focusing is achieved through a bent silicon crystal with a specially designed exit surface. The focused electron beam was then directed onto a water phantom to evaluate the resulting energy deposition profile.

16:00 Functional design of a wideband RF system for HeLICS synchrotron

Within the framework of the NIMMS (Next Ion Medical Machine Study) initiative at CERN, a comprehensive design study is being performed for the Helium Light Ion Compact Synchrotron (HeLICS), a compact accelerator for hadron therapy. A key component of this facility is the radiofrequency (RF) cavity. Its proposed design is based on the wideband technology successfully implemented in the CERN PS Booster. It comprises four cells filled with FINEMET material that enable the acceleration of protons and $^4He^{2+}$ over a broad energy range. The cavity, designed to deliver a peak voltage of up to 2 kV within a frequency range up to 10 MHz, features a compact design to meet the stringent requirements of a compact medical accelerator. It operates in double-harmonic mode, to effectively reduce longitudinal line density and mitigate space-charge effects at low energy. The combination of compactness and operational flexibility positions this RF cavity as an optimal solution for compact synchrotrons, enabling more efficient, precise, and accessible hadron therapy for cancer treatment.

Speaker: Vincenzo Sansipersico (Riga Technical University)

16:00 Impedance analysis for the ALS-U kickers

We present recent impedance modeling studies of the kicker systems developed for the Advanced Light Source Upgrade (ALS-U), including ferrite-loaded kickers, stripline-type fast kickers, and septa. The modeling supports the injection/extraction systems to ensure beam stability in the accumulator and storage rings. In addition, it provides guidance for component fabrication and offline testing by incorporating realistic factors such as mechanical tolerances and assembly specifications.

Speaker: Qing Ji (Lawrence Berkeley National Laboratory)

16:00 Improving the SPS beam extraction efficiency by implementation of a crystal septum

The third-integer resonant extraction of the proton beam from the Super Proton Synchrotron (SPS) at CERN is a technique used for slow extraction of the circulating beam, providing a constant spill of protons to the North Area experiments.
Currently, this method employs an electrostatic septum (ZS) to separate the extracted particles from the proton beam circulating in the ring. However, a fraction of the protons is lost on the mechanical parts of the ZS causing its activation, thus, limiting the efficiency of the process.
In this work, the first considerations for solving this problem are presented with the implementation of a non-resonant slow extraction scheme that enables the extraction of the particles without the use of the ZS.
The extraction efficiency and beam quality are benchmarked using the Xsuite particle tracking framework for a new configuration, which is compared with the present setup.

16:00 Injection simulations of space charge dominated proton beams in IOTA

A 2.5 MeV proton injector is being constructed for the IOTA ring at Fermilab to study the interaction of nonlinear integrable optics (NIO) with high space charge beams. Space charge in the transport line from the RFQ to the injection location has a significant current dependent effect on the phase space. Simulation studies to support efficient injection of intense bunches into IOTA are presented, included schemes to inject directly into NIO lattices.

Speaker: John Wieland (Fermi National Accelerator Laboratory)

16:00 Installation, operations, and upgrade of a CS-30 cyclotron for the production of alpha emitters At-211 and Ac-225 at the Ionetix TAT facility

Ionetix Corporation has been conducting research and development on compact superconducting cyclotrons for medical isotope production, with multiple Ion-12SC units installed and operated at customer sites in USA. Since 2021, we have also focused on the production of alpha-emitting medical isotopes for cancer therapy, specifically At-211 and Ac-225. As a first step, Ionetix acquired an existing, partial CS-30 Cyclotron system decommissioned and stored in a warehouse. We refurbished and upgraded the CS-30 cyclotron, replacing components as needed. The installation of the CS-30 was completed in 2022, and it has been operational, accelerating alpha and proton beams since 2023. The refurbished cyclotron features new main and trim coils, a new internal bismuth target and drive, and a new central region to enhance the beam-on-target performance. All power supplies, controls, and instrumentation were replaced with commercially available components. The first production of At-211 at Ionetix was achieved in April 2023, followed by the first production of Ac-225 in June 2024. This paper analyzes and describes the CS-30 cyclotron, and the upgrades and enhancements developed at Ionetix.

Speaker: Xiaoyu Wu (Ionetix Corporation)

16:00 Investigation and mitigation of magnetic field emissions in the SMH16 septum system's high-current cable connections

The SMH16 system at CERN is a pulsed septum magnet driven by a single period of a flattened sine wave current with a fundamental frequency of approximately 2.5 kHz and a peak current of 28 kA. The magnet connects to its pulse generator via ten high-voltage, high-power cables, each containing go, return, and ground conductors and coarse shielding. Due to the high currents, magnetic field emissions could interfere with nearby equipment and affect electromagnetic compatibility.
This work investigates these magnetic field emissions and evaluates potential shielding measures. 2D field simulations of the cable connections to model the emissions and assess the effectiveness of additional shielding configurations have been conducted. To validate the simulations, time-dependent magnetic field measurements using a magnetic near-field probe, and a custom Hall probe were performed on a section of the cable connection in a full-scale test setup of the SMH16 system, both with and without extra shielding around the cable bundle.
The results showed good agreement between simulations and measurements. Additional shielding can significantly reduce magnetic field emissions.

Speaker: Konstantinos Papastergiou (European Organization for Nuclear Research)

16:00 J-PARC neutrino beamline upgrades towards 1.3 MW beam power for long baseline neutrino oscillation experiments in Japan

Realization of high intensity neutrino beam over 1 MW beam power is crucial to search for CP violation in lepton sector. J-PARC Main Ring (MR) accelerator and neutrino beamline are being upgraded toward 1.3 MW beam power for Hyper-Kamiokande experiment, a future long baseline neutrino oscillation experiment in Japan, by shortening repetition cycle (2.48 to 1.16s) and increasing beam intensity (2.6x10^14 to 3.2x10^14 protons per pulse).
During long shutdown in 2021 and 2022, neutrino beamline DAQ and control system have been upgraded for the shorter cycle and magnetic horn system has also been upgraded for higher current operation (250 to 320 kA).
MR and neutrino beamline operation was resumed in 2023 after the long shutdown. The magnetic horn system is successfully being operated at 320 kA for physics running, which enables 10% more neutrinos at the far neutrino detector. The stable operation of MR and neutrino beamline was achieved at 800 kW so far. Further upgrades of MR and neutrino beamline are ongoing to achieve 1.3 MW beam by 2028.
In this presentation, operation experience of the neutrino beamline, and status and prospect of the beamline upgrades are presented.

Speaker: Tetsuro Sekiguchi (High Energy Accelerator Research Organization)

16:00 Laser wakefield accelerator-driven photonuclear reactions for the production of medical radionuclide 67Cu

Recent results of production of the medical radionuclides 67Cu using a laser wakefield accelerator (LWFA) are presented. This emerging technique utilises powerful, ultrashort laser pulses that are focussed into a gas jet to create a plasma wake that traps and accelerates electrons to very high energies with large accelerating gradients. Accelerated electrons interact with high-Z material to produce high-energy photons by bremsstrahlung, which then produce 67Cu via the 68Zn(γ, p)67Cu photonuclear reaction.
67Cu, with 62 h half-life, is considered ideal radioisotope for treatment of lymphoma and colon cancer.* The production of 67Cu requires medium-energy (~70 MeV) protons that are only available at limited number of facilities.
We present the experimental setup, maximising electron pulse intensity by optimising laser beam properties and target composition of gas jet. The gamma beam and the design of 68Zn are optimised using FLUKA simulations. We will also report on the development of detectors for online monitoring of the electron and gamma beams, and produced activities of the radionuclides.

Speaker: Baris Bingol (University of Strathclyde)

16:00 Measurement of the muon rate at the SND Experiment with the Timepix3 radiation monitor

Using a Timepix3 radiation monitor, the muon rate at the Scattering and Neutrino Detector (SND) location at the Large Hadron Collider (LHC) was measured during luminosity production at the ATLAS collision point. Filters are applied on the measured data to distinguish between background radiation and the muon signal by analyzing the cluster type, length, and angle. The results were compared to the those reported by SND, revealing a count rate ratio of 1.24 of Timepix3 to SND measurements. Taking advantage of the Timepix3 detector capabilities, further features of the muon flux are studied. First, the bunch-by-bunch spacing (25 ns) of the beam is assessed owing to the time resolution of the Timepix3 detector (1.5265 ns). The spatial distribution of the muon flux in the Timepix3 detector surface has been studied, however the detector size is too small for the measured muon rate to yield any distinct patterns, assuming the muon gradient as measured by the SND detector. Finally, the energy deposition $E_{dep}$ of the muons in the Timepix3 detector has been studied, consistent with FLUKA simulated muons coming from ATLAS collisions, with an energy distribution peaked at 100 GeV.

Speaker: Volodymyr Rodin (European Organization for Nuclear Research)

16:00 Measurement of the transversal Muon Rate at the proposed CODEXb experiment with the Timepix3 Radiation Monitor

Using a Timepix3 radiation monitor, we measured the muon rate at the proposed CODEXb experiment location within the Large Hadron Collider (LHC) during luminosity production at the LHCb collision point. Filters were applied to the data to differentiate the background radiation from the muon signal by analyzing the particle track morphology—specifically cluster type, length, and angle within the detector. The resulting filtered muon rate was determined to be 8.6$\pm$1.5 counts/(cm $ \cdot$ pb$^{-1}$). These results were further compared to simulations performed with the FLUKA Monte Carlo code, showing agreement within the uncertainties.

Speaker: Daniel Söderström (European Organization for Nuclear Research)

16:00 New linac designs by High Energy Sources R&D Group at Varex Imaging

High Energy Sources R&D group at Varex Imaging has developed several Accelerator Beam Centerline (ABC) and Linear Accelerator (linac) designs in the past 8 years. Here we present a summary of our recent progress. M9V linac, featuring our new ABC, is being developed to further improve characteristics of 9 MeV accelerator. The new ABC is shorter than the standard 9 MeV linac, and the focusing solenoid is completely removed. The overall system design increases dose rate and reduces the weight and complexity. In addition, our new version of K15, called K15V or V15, is being redesigned with a hybrid Standing Wave (SW) and Traveling Wave (TW) reverse feed configuration, protected by US patent. We expect it to produce significantly higher dose rate of up to 40000 R/min at 1 m. The first SW section of this linac may be used separately in 9 MeV system we called V9, which is also expected to deliver higher dose rate of up to 20000 R/min while substantially reducing neutron yield compared to 15 MeV machine. We have also tested a new concept implemented on 6 MeV linac, which permitted reducing the electron beam focal spot size to 350±150 µm without utilization of any magnetic systems.

Speaker: Stanislav Proskin (Varex Imaging (United States))

16:00 Optimising focusing parameters of very high energy electron beams for radiotherapy using Monte Carlo simulation

Very high energy electron (VHEE) beams, with energies of 100 MeV and above, offer favourable properties for radiotherapy, such as deep penetration depth and reduced sensitivity to tissue heterogeneity. Numerous simulation and experimental studies have investigated these properties for clinical application. In this study, we use Monte Carlo simulation using TOPAS to obtain the depth-dose profiles of VHEE beams with varying energy and focusing parameters. An empirical model is fitted to the central axis dose, yielding parameters that characterise the depth-dose profile. A linear interpolator then maps these fitting parameters to the focusing parameters, allowing us to identify the optimal focusing parameters. The results presented here are independent of the beamline and can therefore guide the design of a final focusing systems for VHEE beams.

Speaker: Paul Giansiracusa (The University of Melbourne, Australian Synchrotron)

16:00 Optimizing magnetic anisotropy and tunnel magnetoresistance in CoFe₂O₄/MgO bilayers through SHI processing

Magnetic tunnel junctions (MTJs) formed by CoFeB and MgO are key components to form memory elements in magnetic random access memory (MRAM) for high-density data storage applications. A thorough understanding of the relation between properties such as magnetic anisotropy (MA) and tunnel magnetoresistance (TMR) is crucial for optimizing the performance of these devices. These properties have been seen to improve by the effects of Swift heavy ion (SHI) irradiation through improved structural and interfacial electronic effects ,**.
This study investigates the effects of Swift heavy ion (SHI) irradiation on magnetic anisotropy and tunnel magnetoresistance properties of CoFe2O4/MgO magnetic bilayer. The results show SHI irradiated thin films have enhanced magnetic anisotropy and transport properties of the thin film. The study also suggests an inverse relation between the two properties, which will be important in making MTJs with high magnetic anisotropy and TMR. This contribution in understanding the enhancement of magnetic and transport properties by SHI irradiation on MTJ is critical in advancing MTJ technology for spintronic applications.

Speaker: Ritika Charak (Panjab University)

16:00 Overview of seven-unit collimator system and its operation for J-PARC main ring

The J-PARC main ring has three linear sections, and one have a beam collimator system downstream of the injection devices to localise beam losses. In September 2024, the seventh collimator unit was installed, completing an upgrade of the collimator system that has been underway since 2012. The system was changed from one that scatters and captures the beam halo to one that draws the jaw close to the beam core and directly removes its halo. This allowed a number of collimator units to be placed in a limited area. The original beam loss capacity in the collimator area was 450 W. Seven collimator units allow a beam loss of 3.5 kW. Currently, six collimator units are used to deliver 800 kW beams to neutrino experiments with losses of less than 500 W. By using seven collimator units, a beam of 1.3 MW can be delivered with a reasonable loss amount. The combination of units effectively removes the halo component of the beam and localises the beam losses. However, the direct removal method can create loss spots downstream of the collimator according to phase advance. This paper describes the operation of collimators in actual beam operation.

Speakers: Yoichi Sato (Japan Proton Accelerator Research Complex), Takaaki Yasui (High Energy Accelerator Research Organization)

16:00 Physical design of a high-power superconducting electron linear accelerator for medical isotope production

Methods for medical isotope production using electron liner accelerator have been investigated in past studies. The accelerators used for medical isotope production increasingly demand high-power electron beams. In this article we present the physical design of a compact superconducting accelerator capable of providing a high average current electron beam with a current of 10 mA and an energy of 40 MeV for medical isotope production. We focused on performing beam dynamics simulations and optimizing the beam parameters at the exit of the accelerator by Multi-Objective Genetic Algorithm. The accelerator employs a Nb3Sn superconducting radio-frequency (SRF) cavity to achieve high average beam power and utilizes a cryocooler conduction-cooling technique for efficient operation.

Speaker: kexin chen (Shanghai Advanced Research Institute)

16:00 Pre-conceptual design of MuSTAR for UNF Transmutation Facilities and US Energy Independence

Muons, Inc. is developing a conceptual design for a UNF Transmutation Facility that is a MuSTAR Nuclear Power Plant (NPP). It is based on a 50 MW superconducting RF proton accelerator that drives a number of subcritical molten-salt (MS) small modular reactors that each have an internal spallation neutron target. The starting points for the components are the ORNL SNS Linac and the ORNL MSRE fueled with UNF that has been converted from oxides to fluorides. This conversion process is described in our GAIN VOUCHER GRANT (ORNL/TM-2018/989) and is noteworthy in that it does not produce a plutonium stream. Online processing of the circulating MS within the sub-critical reactor containment envelope continuously removes lighter volatile radioisotopes, neutron poisons, and useful materials while leaving heavier actinides in the MS to be consumed to produce energy and to reduce the lifetime of the remnants. Molten salts, unlike solid fuel elements, do not suffer fatigue and failure due to large temperature variations as fission is turned off and on due to beam trips.

Speaker: Rolland Johnson (MuPlus, Inc.)

16:00 Progress of beam power upgrade in J-PARC main ring

In the J-PARC main ring (MR), a project to increase the beam power with higher repetition rates and higher beam intensities is now in progress, aiming to achieve 1.3 MW in the fast extraction (FX) mode and >100 kW in the slow extraction (SX) mode. Beam power has generally been increasing as planned with progress of hardware upgrades and beam dynamics tuning; beam powers of 800 kW (FX) and 80 kW (SX) have been achieved as of December 2024. This paper reports on the recent progress of the beam power upgrade in MR.

Speaker: Yoichi Sato (High Energy Accelerator Research Organization)

16:00 Radiation levels from a Beam Gas Curtain instrument at the LHC at CERN during ion operation

A prototype Beam Gas Curtain (BGC) monitor was installed on beam 1 at the Large Hadron Collider (LHC) at CERN to provide 2D images of the transverse beam profile during the ongoing Run 3 (2022 - to date) and in view of the High Luminosity LHC upgrade (HL-LHC). By design, the BGC operation generates collisions between the beam particles and an injected gas jet proportionally to the beam intensity and the gas density, possibly causing radiation-induced issues to the downstream LHC equipment. This operation has been studied for the proton run, and now the scenario for lead (Pb) ion beam is scrutinized. The radiation showers from the BGC are characterized using measured data from different LHC radiation monitors during the Run 3 BGC operation, along with Monte Carlo simulations with the FLUKA code. Finally, predictions of the expected radiation showers during operation of the BGC in the HL-LHC era are discussed.

Speaker: Daniel Söderström (European Organization for Nuclear Research)

16:00 Radiation shielding design for Hefei Advanced Light Facility - Accelerator Test Facility

The Hefei Advanced Light Facility - Accelerator Test Facility (HALF-ATF) is equipped with a linear electron accelerator capable of achieving a maximum energy of 120 MeV, which is utilized for the debugging of the pre-injector and essential equipment. The electron beam is produced by an electron gun and subsequently accelerated to 120 MeV via a buncher and accelerating tubes, ultimately being absorbed in a beam dump. It is important to note that beam loss is unavoidable during the processes of acceleration, transport, and storage. The characteristics of beam loss differ across various regions, and these factors directly determine the thickness of the primary shielding wall as well as the radiation dose levels outside the shielding. The radiation shielding system of HALF-ATF comprises the main shielding, mazes, shielding doors, and the beam dump. The design of the HALF-ATF radiation shielding system integrates theoretical calculations, Monte Carlo simulations, and practical engineering methods.

Speaker: Jia Chen (University of Science and Technology of China)

16:00 Readiness of the HEARTS@CERN facility for space electronics high-energy heavy-ion testing

The HEARTS@CERN activity in the framework of the HEARTS (High-Energy Accelerators for Radiation Testing and Shielding) EU project is targeted at enhancing Europe’s high-energy (>100 MeV/n) heavy ion electronics irradiation capability through the development of an irradiation beam combining unique penetration and ionization characteristics. These types of tests are essential for exploiting commercial electronics in space.
Throughout 2024, the HEARTS@CERN efforts have focused on achieving and demonstrating compliance with the space user radiation effects testing requirements. This includes being able to offer a wide range of energies (and Linear Energy Transfer values) and fluxes, with a high level of accuracy and a rapid change between parameters. Moreover, large homogeneous beams are necessary for enabling the test of multiple electronic components in parallel, and for performing board level testing.
This work will present requirements for high-energy heavy ion testing along with the level of compliance achieved, as demonstrated during the November 2024 HEARTS@CERN user run, with a focus on the beam related parameters, but including also facility and procedural considerations.

Speaker: Daniel Söderström (European Organization for Nuclear Research)

16:00 Recent developments in delivering mixed helium and carbon ion beams at MedAustron

Simultaneous irradiation with mixed helium and carbon ions is being proposed for online range verification in carbon radiotherapy. In 2024, a mixed $^4$He$^{2+}$ and $^{12}$C$^{6+}$ beam, generated by sequential injection of helium and carbon ions into the synchrotron, was extracted successfully for the first time at the MedAustron ion beam therapy and research center. This double injection scheme comes with challenges concerning the capture, acceleration, and slow extraction, as injection energy offsets and differences in horizontal phase distributions have to be considered in addition to the small offset in charge-to-mass ratio between $^4$He$^{2+}$ and $^{12}$C$^{6+}$. This proceeding reports on recent developments in the delivery of this mixed ion beam at MedAustron using a double injection scheme, which includes an additional deceleration ramp for helium ions between the injections of helium and carbon, as well as progress towards a measurement setup for the time-resolved quantification of the ion mixing ratio at delivery.

Speaker: Matthias Kausel (EBG MedAustron GmbH)

16:00 Recommissioning of a semi-industrial electron accelerator after a long shutdown

Radiation processing technology started in Tunisia by the installation of a pilot plant gamma irradiator in 1999 and an electrons beam accelerator in 2009 at the National Centre for Nuclear Science and Technology CNSTN. These facilities are established with the support of the International Atomic Energy Agency IAEA. The electrons-beam facility is equipped with CirceIII Linac accelerator, 10 MeV of energy and beam power up to 10 kw, using a conveyor roller system for industrial applications such as sterilization of pharmaceutical single use products and scientific research activities.
After a long shutdown from 2011 to 2017 due to some technical problems and the replacement of a muster compoments PFN, the machine was succefully restarted. For this reason a second qualification has been established, allowing the operation of the facility for researsh and commercial activities.
The presentation will show all aspects of the facility qualifications "IQ; OQ; PQ" according to international standards.

Speaker: Mohamed Hedi TRABELSI (CNSTN)

16:00 Reduction of beam loss at the fast extraction section in J-PARC MR

At J-PARC MR, proton beams are supplied to the neutrino facility via fast extraction (FX). The beam power, which was 500 kW in 2021, reached 800 kW by June 2024, with further upgrades planned. This increase in power has led to a rise in beam loss in the FX section, necessitating countermeasures. Residual doses are high at positions where the FX beam orbit closely approaches the aperture, and the effectiveness of beam loss countermeasures is evaluated by changes in residual dose. By June 2024, residual doses were successfully reduced through adjustments to the beam optics. For further reduction of beam loss, in July 2024, the aperture was expanded at the most upstream position where the beam orbit is in close proximity to the aperture. This report discusses the achievements during subsequent FX operations and outlines plans for further improvements.

Speaker: Soma Iwata (High Energy Accelerator Research Organization)

16:00 Research and development study on nanobeam formation using laser-cooled ions for high-precision single-ion irradiation

To realize high-precision single-ion irradiation or implantation, we have proposed a nanobeam formation scheme where single cold ions selectively separated from a two-component Coulomb crystal in a linear Paul trap (LPT) are accelerated to 100 keV and focused on the nanometer scale using electrostatic bipotential lenses. The entire process of laser cooling of trapped ions in the LPT, ion-selective ejection from the LPT, acceleration, and focusing in the lens system is investigated by detailed multiparticle tracking simulations to show the feasibility of ultralow-emittance nanobeam formation and ion focusing properties. According to the simulation results, the fabrication and commissioning of such a single-ion irradiation system are ongoing at Takasaki Institute for Advanced Quantum Science, National Institutes for Quantum Science and Technology toward the application of research and development of quantum materials and devices. We will discuss the simulation results on the behavior of cold ions in the irradiation system and report the latest status of the system development including preliminary experimental results.

Speaker: Yosuke Yuri (National Institutes for Quantum Science and Technology)

16:00 Resonance island formation due to adiabatic tune change in RHIC

A stored proton beam may become unstable when the horizontal tune slowly approaches a quarter integer resonance.This paper discusses this phenomenon in the context of an Accelerator Physics Experiment that was conducted in the Relativistic Heavy Ion Collider, in which the horizontal tune was ramped through a fractional tune of 0.75 in the presence of strong octupolar fields.

Speaker: Henry Lovelace III (Brookhaven National Laboratory)

16:00 Simulation studies on bent silicon crystals for loss reduction in slow extraction operation at J-PARC Main Ring

Reducing beam loss during slow extraction remains a critical challenge for the J-PARC Main Ring, which aims to enhance beam power for its 30 GeV proton beam. Since beam loss during slow extraction mainly occurs at the electrostatic septum, it is important to reduce beam loss at this location. Researchers at CERN SPS have recently reported that beam loss can be reduced by installing bent silicon crystals in the accelerator ring and utilizing their charged particle deflection effect. In this paper, we report the results of a simulation study on the expected beam loss reduction effect when the bent silicon crystal is installed upstream of the electrostatic septum of the J-PARC Main Ring and the beam deflection effects of the bent silicon crystal, called channeling or volume reflection, are utilized. The required size and installation position of the silicon crystal, and the required accuracy for adjusting the position and angle will also be reported.

Speaker: Ryotaro Muto (High Energy Accelerator Research Organization)

16:00 Simulations of beam halo distributions for a feasibility study of in-vacuum gravitational experiments at the LHC

Within the realm of general relativity, the measurement of signals coming from relativistic celestial bodies have offered great insights. However, the relatively low frequency of these signals and the lack of control over their source may make the creation of well-controlled laboratory environments desirable. One possibility is to measure the relativistic beams in the Large Hadron Collider (LHC) at CERN using a milligram-scale monolithic pendulum. This would offer the possibility to test general relativity and alternative theories of gravity in an entirely new parameter regime, where the source of gravity is the almost pure kinetic energy of the ultra-relativistic particles. The low-bandwidth of the source, combined with the controllability of the setup, may offer new opportunities and insights in gravity-related research. To design the experiment, it is necessary to analyze the factors that contribute to the deterioration of the signal-to-noise ratio. One of the contributors is the impact on the pendulum of beam halo particles. This paper presents an initial assessment of the impact of beam halo on the detection of gravitational signal.

Speaker: Pascal Hermes (European Organization for Nuclear Research)

16:00 Simulations of magnetic field effects on 3-GeV proton beam brought by magnets for muon beam in future proton beam transport line of J-PARC

A high-power 3-GeV proton beam from a rapid cycling synchrotron (RCS) is transported to targets for muon and neutron production at Materials and Life Science Experimental Facility (MLF) by a 3-GeV RCS to Neutron facility Beam Transport (3NBT) line in J-PARC. Recently, the design power of 1 MW has been achieved, which has initiated a future plan of MLF second target station (TS2). For the future plan, design studies have been started for a new beam transport line to the TS2 target, which works as a source for both muon and neutron. In this study, 3-GeV proton beam transport is simulated in the vicinity of the TS2 target, where a bending magnet for muon separation and a capture solenoid are aligned. In this presentation, we report magnetic field effects on the proton beam brought by those magnets and correction of the effects.

Speaker: Yuji Yamaguchi (Japan Atomic Energy Agency)

16:00 Spill optimization system improving slow extraction at GSI

Resonant slow extraction is routinely used to provide ion beams to various users. At GSI SIS18, two extraction methods are implemented: quadrupole-driven and Radio Frequency Knock Out (RF-KO) extraction. In either case, delivering a defined beam intensity (spill) without fluctuations or drifts is desired for an efficient beam usage. The Spill Optimization System (SOS) was developed to address this demand and improve the spill quality based on online spill monitoring. Developed using software-defined radio technology, it comprises a feedback controlling the spill rate and an optimization algorithm to improve the spill quality. In the case of RF-KO extraction, it controls the spill by generating tailored excitation signals for the KO exciter. For quadrupole-driven extraction, it produces a control signal for the tune ramp including tune wobbling to improve the spill quality. This contribution gives an overview on the systems and compares different usage scenarios.

Speaker: Philipp Niedermayer (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Status of J-PARC accelerator chain

The Japan Proton Accelerator Research Complex supplies a high-intensity proton beams for the physics experimental programs in the Material and Life Science Facility (MLF), the Hadron experimental facility and the neutrino target. In such a high-intensity hadron accelerator, losing less than 0.1% of the beam can cause several problems. Such lost protons can cause serious radioactivation and accelerator component malfunctions. Therefore, we have been continuing a beam study to achieve high-power operation with enough smaller loss condition. In addition, we have also improved and maintained the accelerator components, enabling a stable operation. Through these efforts, we established a beam power of 1-MW operation for the MLF users and a beam power of 800-kW operation for the neutrino users. In this paper, Recent achievement is summarized.

Speaker: Kazami Yamamoto (Japan Proton Accelerator Research Complex)

16:00 Status of the pulsed hydrogen gas stripper project at GSI

The operation of the specifically upgraded pulsed gas stripper development setup for the user beamtime lasted until July 2024. It was very successful in terms of both providing stripped ions and gaining valuable experience in the long-term operation of the pulsed stripper. The long periods of high duty nitrogen operation revealed a severe service life issue of the fast injection valves, which was already anticipated in the risk assessment for the hydrogen operation. This emphasizes the need for the safety measures incorporated in the design of the pulsed stripper facility. During the user beamtime, several measurement campaigns were conducted. Extensive data on the stripping efficiencies for 12 projectile-target combinations could be obtained. In this contribution the obtained results and lessons learned are presentet as well as the necessary next steps to finaly bring the hydrogen stripping to routine operation.

Speaker: Michael Maier (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Status update of the laser-hybrid accelerator for radiobiological applications

The Laser-hybrid Accelerator for Radiobiological Applications (LhARA) is a transformative approach to ion-beam therapy and radiobiological research. Serving the Ion Therapy Research Facility (ITRF), LhARA proposes to use a laser-driven proton and ion source, combined with advanced beam delivery systems, to provide highly flexible, high-repetition-rate, and ultra-short ion bunches suitable for groundbreaking studies in radiobiology.
Following the recent publication of the LhARA Conceptual Design Report, the LhARA/ITRF project has entered a new phase of research and development. Here, we present a status update on recent LhARA progress. Highlights include improved understanding of the simulated beam generated at the source as well as subsequent impact on beam dynamics with co-propagating electrons, the latest descriptions of the FFA magnets including simulated fields and tune calculations in particle tracking and updated to beam delivery schemes in LhARA’s end stations for generating flexible beam conditions.

Speaker: Ta-Jen Kuo (Imperial College London)

16:00 The Experimental Storage Ring (ESR) - recent developments

The Experimental Storage Ring (ESR) at GSI Darmstadt, Germany is the core instrument for unique physics experiments. It is operated for accumulation, storage, cooling and deceleration of a wide range of heavy ion beams in the energy range from 4-400 MeV/u coming from the synchrotron SIS18 via the FRagment Separator (FRS) or a direct transport line. Low energy decelerated beams can also be fast extracted to the storage ring CRYRING or to the HITRAP facility.
The overview of the ESR performance, will be presented here.
The features and challenges of the operation with the new control system LSA (LHC Software Architecture) will be outlined as well.

Speaker: Sergey Litvinov (GSI Helmholtz Centre for Heavy Ion Research)

16:00 The latest design for a future short-baseline neutrino beamline

The ENUBET and NuTAG projects propose the measurements of the $\nu_e$ and the $\nu_\mu$ cross sections at the relevant energies of Hyper-Kamiokande and DUNE. While ENUBET focuses on a fully instrumented decay tunnel to achieve a precise flux measurement, NuTAG proposes the use of silicon-pixel detectors to achieve the \textit{full tagging} of the parent meson and the daughter lepton. Both ideas have merged into the Physics Beyond Colliders (PBC) Short-Baseline Neutrino (SBN) beamline study, supported through the PBC initiative at CERN. If deployed at CERN, the SBN beamline would need to be compatible with the operation of the current injector complex including the new SHiP experiment, in particular with respect to the number of protons required. The beamline's intensity requirement must therefore be kept at a minimum. With that in mind, a full optimization of the beamline was conducted to maximize the production of hadrons while fulfilling pile-up and background constraints. This contribution presents the optimized beamline design, elaborating on the techniques used and challenges faced during the design process.

Speaker: Marc Jebramcik (European Organization for Nuclear Research)

16:00 The radiation monitoring system for Super Tau Charm Facility - Beam Test Platform

Super Tau Charm Facility - Beam Test Platform (STCF - BTP) is a verification facility for Super Tau Charm Facility. A complex radiation environment consisting of particles with different types and energies will be produced. An advanced monitoring system is being developing to measure the radiation dose rate for STCF - BTP. The radiation monitoring system combines the function of data collection, data storage, dose alarming. This paper describes in detail the implementation of the system infrastructure and functions.

Speaker: Jia Chen (University of Science and Technology of China)

16:00 The study of the center precision of the gantry of the proton therapy device

The Shanghai Proton Therapy Device (SAPT) is the first domestic proton therapy system, and China has a truly self-developed and marketable domestic high-end proton therapy device. The gantry is an important part of the proton therapy device, which has the characteristics of large inertia, large size, and large weight, and at the same time requires high motion positioning accuracy and reliability. In this talk, I will discuss the 360° gantry and superconducting gantry structures, and introduce some studies on the accuracy of the center of peer. Through software simulation, we studied the displacement of the equicenter point during the rotation of the gantry, and made some creative improvements to the structure, so that the displacement we were concerned about was controlled below 0.5mm, and the simulation results were regularly analyzed. Our results reveal the changes and influencing factors of the central point such as the rotation process of the gantry, and pave the way for the application of superconductivity technology in the gantry.

Speaker: yunjing wang (Shanghai Synchrotron Radiation Facility)

16:00 Towards axion searches with polarized hadron beams at GSI/FAIR

Axions, originally introduced to solve the strong CP problem, are leading dark matter candidates appearing in various Standard Model extensions. At low masses, axion-like particle (ALP) dark matter behaves as a classical field, potentially detectable when its frequency resonates with a beam's spin-precession frequency.
The JEDI collaboration's proof-of-principle experiment at COSY set upper limits on oscillating EDMs caused by ALPs, though no signals were observed. This presentation discusses COSY results and recent efforts to explore the feasibility of conducting axion search experiments using existing accelerators at GSI/FAIR with polarized hadron beams.

Speaker: Daoning Gu (GSI Helmholtz Centre for Heavy Ion Research, Forschungszentrum Jülich, RWTH Aachen University)

16:00 Towards tailored beam distributions for fixed target experiments at CERN

The time-of-flight (nTOF) facility at CERN uses neutrons produced by a proton beam interacting with a fixed target. To prevent target damage, an upper bound on the peak energy density has been imposed. Adhering to this constraint requires a large beam size. Similarly, at CERN’s North Area, a large beam size is required at the septa splitting the beam towards different experiments. However, both cases suffer from limitations associated to losses of the primary beam, leading to poor transmission efficiency and high radioactive activation. This paper proposes an alternative approach by manipulating the beam distribution. Given the absence of strong nonlinear elements in both transfer lines, the focus shifts to tailoring the distribution before extraction.

Particle tracking simulations are presented alongside experimental results, characterizing the phase space distribution as a function of machine parameters. Advanced deep learning methods that enable efficient exploration of the parameter space are also discussed.

Speaker: Francisco Huhn (European Organization for Nuclear Research)

16:00 Towards the detection of mixed helium and carbon ion beams using a gas-filled charge exchange cell

Irradiation with mixed helium and carbon ion beams is emerging as a promising approach to treatment monitoring in ion radiotherapy. In contrast to mono-isotopic beams, the full characterization of the mixed beam requires distinguishing ion species of almost identical charge-to-mass ratio, which is not feasible with most conventional beam diagnostic devices. This proceeding proposes a measurement concept that could allow for determining the ion mixing ratio after extraction from the ion source at energies around 10 keV/u. The concept relies on a gas-filled charge exchange cell, where the traversing ions experience electron capture events, followed by an electrostatic or magnetic analyzer and beam intensity measurement. The proposal is accompanied by proof-of-concept measurements performed at the Helmholtz Zentrum Dresden-Rossendorf (HZDR), which showcase the potential but also several challenges associated with the measurement concept.

Speaker: Matthias Kausel (EBG MedAustron GmbH)

16:00 Ultra-high spatial resolution in micron scale achieved by a practical cascade high energy electron radiography in HERPL

As a new scheme, High Energy Electron Radiography (HEER) was considered as one of the novel mesoscale diagnostic methods for high energy density matter (HEDM) because of powerful penetration, high space-time resolution and large density dynamic diagnosis range. In this work, we R&D a practicle cascade HEER composed of a electromagnetic beamline and a permanent magnet HEER in High Energy Electron Radiography Research Platform in Lanzhou (HERPL). The field of view of the cascade HEER is about Φ3mm, and its total length is half that of the electromagnetic HEER with the same magnification. 50 MeV electron beams with picosecond pulse width bunch were used to image a TEM grid to study the spatial resolution. The excellent result was obtained with spatial resolution about 0.6 μm. In addition, electron bunch train and ultra-fast imaging acquisition system prepared for dynamic HEER were studied in this paper.

Speaker: Shuchun Cao (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Update on the performance of the Compact Compton Source ThomX

The ThomX Compact Compton Source comprises an electron linac, an electron storage ring and a Fabry-Perot cavity. The electrons interact with laser photons at the intersection of the storage ring and the Fabry-Perot cavity. The facility started its commissioning in 2021 and the first X-rays were observed in June 2023. The operation energy was increased from 50 MeV to 70 MeV in 2024. We present some difficulties encountered during the commissioning phase, how they were addressed and the main performances achieved so far.

Speaker: Nicolas Delerue (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

16:00 Uranium spallation neutron targets for UNF transmutation

Muons, Inc. and its collaborators propose to improve solid uranium spallation targets to provide more neutrons per incident proton, longer lifetime, and corrosion control for:

The design of Muons Subcritical Technology Advanced Reactor (Mu*STAR) combines two remarkable ORNL accomplishments: the 1 GeV Superconducting Proton Linac of the Spallation Neutron Source (SNS) and the 1965-1969 Molten Salt Reactor Experiment (MSRE).
Combining these two technologies is a spallation neutron target in the middle of each Small Modular Reactor that produces neutrons that initiate transmutation decay chains that produce heat as they die out in the subcritical molten salt core.

Speaker: Mary Anne Cummings (Muons (United States))

17:40 High-power testing of TPS heterogeneous one-to-four power combining

The Taiwan Photon Source (TPS) is a third-generation synchrotron light source located in Taiwan. Currently, it operates with two RF stations, each capable of delivering 300 kW of RF power. As the number of beamlines at TPS increases, more insertion devices will be installed, necessitating additional RF power. Presently, each RF station provides approximately 250 kW of power. To maintain operational margin, increasing the RF power available per station is a critical task. To address this, we have implemented a heterogeneous power combination method, where the power from solid-state power amplifiers is combined to raise the available RF power per station to 375 kW. This report describes the power combination methodology employed at one of the RF stations, high-power testing results, and the outcomes of long-term operation under combined power conditions. Future plans for power combination are also discussed in this paper.

Speaker: Zong-Kai Liu (National Synchrotron Radiation Research Center)

16:00 → 18:00 Tuesday Poster Session: TUPM

16:00 A compact linear accelerator coaxially integrated with a high-power microwave source

Particle accelerators have long been instrumental in advancing scientific research, medical treatments, and industrial processes. However, traditional radio-frequency accelerators are encumbered by their size, expense, and reliance on external microwave sources.
In this paper, we propose a novel linear accelerator concept that integrates a high-power microwave source directly into the accelerator, which eliminates the need for external microwave drivers, resulting in a more compact, cost-effective, and simplified system.
We designed an X-band backward wave oscillator driven by a hollow continuous electron beam of 50 keV, the high-power microwave generated from which is then input to a centrally positioned X-band standing-wave acceleration structure via a radial coupler. The witness beam, traversing the acceleration structure, can be accelerated from 50 keV to higher than 4 MeV through 10 acceleration cells.
This scheme serves as a fundamental exploration of the possibilities of integrated accelerator designs, paving the way for further innovations in the field of more efficient, scalable and versatile accelerator systems.

Speaker: Zi-Jing Zhang (University of Science and Technology of China)

16:00 A high-efficiency dielectric wakefield energy booster for CLARA

Structure-based wakefield acceleration, using dielectric-lined or corrugated waveguides, is a novel acceleration method currently being explored by several research groups globally. This technology facilitates the transfer of energy from a high-charge drive beam to a lower-charge main bunch with high accelerating gradients. In this study, we propose an energy booster for the Compact Linear Accelerator for Research and Applications (CLARA) at Daresbury Laboratory, utilising dielectric wakefield acceleration (DWA). Our simulation study optimises the drive beam and structure to achieve maximal energy efficiency across varying main beam energies, enabling the delivery of a main beam with adjustable charge and final energy. Additionally, we have considered the stability of both the accelerated and drive beams, selecting the geometry and layout of accelerating structures to maximise accelerated beam quality and mitigate the development of beam breakup instability in the drive beam

Speaker: Toby Overton (Science and Technology Facilities Council)

16:00 A new deposition method for potassium cesium antimonide photocathodes about increasing the potassium content towards theoretical stoichiometry

As accelerators and electron microscopes become more advancement, high-performance photocathodes are required. In particular, CsK$_2$Sb photocathode is of interest because of its low emittance, excitability in visible light, and high quantum efficiency (QE). Two challenges with CsK$_2$Sb photocathodes are (1) the lack of a universal deposition recipe to achieve crystal stoichiometries and (2) their high susceptibility, which restricts their operation pressure to ultrahigh vacuum and leads to a short lifetime and low extraction charge. To resolve these issues, it is essential to understand the elemental compositions of deposited photocathodes and to correlate them to active pressures and lifetimes. Here, we report depth profiles for potassium cesium antimonide photocathodes, investigated using synchrotron radiation x-ray photoelectron spectroscopy, and their active pressures.

Speaker: Mr Lei Guo (Hiroshima University)

16:00 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)

16:00 A proposal of superconducting RF electron gun with the latest 4K superconducting technology for CW high-brightness electron beam generation

A superconducting accelerator is an excellent technology that can efficiently accelerate high-current beams and is being applied to free electron lasers and next-generation linear electron-positron colliders such as ILC. Not only for the fundamental science, but also the high current electron beam plays a rather important role in industrial and medical applications. This is because the demand for high-current beams is also strong in these applications. While superconducting accelerators are becoming more widely used, there are not many examples in practical use of the superconducting RF gun, such as the ELBE RF Gun in HZDR. The entire accelerator should be superconducting for its energy efficiency and technical compatibility.　To bridge this technical gap, we propose a superconducting RF gun utilizing the latest 4K superconducting technology, which can generate continuous, high-brightness beams.

Speaker: Masao Kuriki (Hiroshima University)

16:00 A report from ISBA24 (The 7th international school on beam dynamics and accelerator technology) in Chiang Mai, Thailand

ISBA24 (The 7th International School of Beam Dynamics and Accelerator Technology) was held in Chiang Mai, Thailand, jointly hosted by Chiang Mai University, Hub of Talents in Particle Accelerators (operated by the Thailand Center of Excellence in Physics), Synchrotron Light Research Institute (Public Organization) and Hiroshima University. ISBA is a series of international accelerator schools initiated in 2018 at Hiroshima, Japan promoted by IINAS(IINAS-NX). ISBA24 was held from November 1 to 9, 2024. The school brought together over 80 participants, including 18 professors and experts, and 64 students from ASEAN countries and beyond. All participants enjoyed intense lectures, practical exercises, student presentations, and social events such as excursions and Thai northern style banquet. An overview of ISBA24 will be presented and human resource development in accelerator science will be discussed.

Speaker: Masao Kuriki (Hiroshima University)

16:00 A study of improving stability and reliability in PAL-XFEL modulator system

In the PAL-XFEL system, an X-ray free electron laser facility, 51 modulator power supplies in total have been operated with thyratron tubes as the high voltage pulse switch devices in order to drive an X-band linearize and 50 S-band klystrons for a beam energy of 10 GeV. PAL-XFEL requires beam energy stability of less than 0.02% and very tight control of the klystron RF phase jitter. The modulator output pulse amplitude stability is directly related to the RF phase jitter. There are several factors to satisfy stability and reliability for the PAL-XFEL modulator. The largest sources of pulse-to-pulse instability are a current charging power supply (CCPS) for PFN charging, thyratron switch parts, and a klystron focusing magnet power supply. This paper describes how to deal with the failures of these devices and the debugging results.

Speaker: Sang-Hee Kim (Pohang Accelerator Laboratory)

16:00 Advanced beam tuning and beam measurements techniques in the CLEAR facility

The CLEAR (CERN Linear Electron Accelerator for Research) facility delivers to a wide user community a 200 MeV electron beam with highly flexible parameters.
Running conditions range from single-bunch to multi-bunch operation, with bunch charges from 10 pC to 1 nC, bunch durations from 100 fs to tens of ps, and
includes tunable momentum (30 MeV/c to 220 MeV/c).
Such a variety of beam conditions poses a challenge to the beam instrumentation and to the beam measurements and tuning techniques, even more so given that quite often a rapid switch from one set of conditions to a very different one is required.
In this paper we present several examples of the techniques developed in CLEAR for this purpose and discuss their advantages and limitations.
Examples include emittance measurements and phase space reconstruction procedures by quadrupole scans and beam based alignment methods.

16:00 An automated Bead-pull method used in the HALF testing

Bead-pull method is a commonly used approach to test and tune the structures of accelerator. Traditionally, this method has been time-consuming. An automated paltform has been developed in this paper, which significantly reduces the time required for the bead pull method and enhances its accuracy. This method has been implemented in the testing of the Hefei Advanced Light Facility (HALF) and has proven to meet the testing requirements of HALF.

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

16:00 An energy recovery proton linear accelerator for muon production

Muons have important applications in both scientific research and industry. In order to produce muons, an effective way is to use a high-power proton beam interacting with a targeting material. After the interaction, the proton beam is disposed of for other purposes. In this paper, we propose a new type of proton accelerator, an energy recovery proton linear accelerator, so that the high-energy proton beam can be reused to give its energy back to the accelerator. This substantially saves the operational cost of the accelerator and also avoids the burden of high-power beam dumps.

Speaker: Ji Qiang (Lawrence Berkeley National Laboratory)

16:00 An extraction scheme for future CEBAF FFA based energy upgrade

Jefferson lab is considering an energy increase from current 12 GeV to 22 GeV for its CEBAF accelerator. This will be accomplished by recirculating 5-6 additional turns through two parallel CEBAF LINACs using an FFA arc at each end of the racetrack. The total recirculation turns would be 10 times, the first four turns use present conventional arcs to make the 180-degree bends from one LINAC to the other. However, the last 5-6 turns will all share a single beam line inside two FFA arcs. This reduces the footprint and the cost of the project significantly. On the other hand, having the trajectories of last 5-6 recirculating beams close to each other makes it challenging to extract beams from different passes with different energies. In this paper we will explain our present extraction system for 12 GeV, our challenges and limitations, and a possible extraction solution for the 22 GeV upgrade with the goal of extracting beam at different turns/energies to different experimental halls.

Speaker: Reza Kazimi (Thomas Jefferson National Accelerator Facility)

16:00 An optimization of the ILC E-driven positron source with the TPE algorithm

The International Linear Collider (ILC) is a next-generation electron-positron collider based on the superconducting linear accelerator. Many positrons are required for the ILC because beams are not reused in linear colliders. Therefore, the ILC electron-driven (E-driven) positron source system should be designed to optimize efficient positron generation. In this study, we optimize the accelerator parameters including the booster linac RF phase and amplitude, ECS RF phase and amplitude, optics over the system, etc. by the black-box optimizer with TPE algorithm. The results of the optimization are presented.

Speaker: Yodai Sasaki (Hiroshima University)

16:00 An update of progress on the design of the diffraction line for the relativistic ultrafast electron diffraction and imaging facility at Daresbury Laboratory

The Relativistic Ultrafast Electron Diffraction and Imaging (RUEDI) facility is an approved project to provide ultrafast capability to UK researchers. The current design involves two separate beamlines for diffraction and imaging but with shared infrastructure including laser pump sources. This presentation describes recent progress in the design of the diffraction line.
The diffraction line has a 2.4 cell S-band RF gun to produce 4 MeV electron bunches. Bunch compression to the sub-10 fs range is carried out with a triple bend achromat design that also suppresses arrival time jitter*. Interchangeable sample chambers are planned to allow wide ranging experiments from both solid samples at room and cryogenic temperatures and liquid and gas targets. Post sample optics are provided to image the diffraction pattern on to a high-resolution single electron sensitive detector. Temporal diagnostics including an RF TDC and THz deflector are included along with a spectrometer at the end of this line to measure beam energy.

Speaker: Tim Noakes (Science and Technology Facilities Council)

16:00 An upgrade to the normal conducting miniature transport line for laser plasma accelerator-driven FELs

In this contribution, we present advancements in upgrading the employed normal-conducting electron beam transport line at the JETI laser facility, University of Jena. To address spectral broadening caused by the large energy spread in Laser-plasma accelerators (LPAs), a transverse gradient undulator (TGU) with an energy acceptance of ΔE/E0 = ±10% has been developed. Although efficiently transporting the electron beam from the LPA to the TGU within this acceptance range required an optimized beam transport line too. Phase-space analysis for single particles across this energy range revealed that earlier transport line designs at KIT exhibited a nonlinear dependence of beam transverse position x on energy deviation, leads to beam dynamics complication. By incorporating combined dipole-quadrupole magnets, maintaining a transport line length of 2.9 m for 300 MeV beams, a linear relationship between transverse position x and energy deviations was achieved, with minimal variation in the phase x' (less than 2.4 × 10−4). This redesigned transport line meets the TGU's dispersion requirements, enabling more precise beam alignment and transport.

Speaker: Axel Bernhard (Karlsruhe Institute of Technology)

16:00 An upgraded multiprobe surface analysis tool for photocathode research and development

STFC Daresbury laboratory has developed a suite of analysis equipment for characterisation of photocathode materials. This includes the TESS spectrometer for measuring the mean transverse energy and a multiprobe surface analysis system for measuring the chemical and physical properties of samples*. Recently, the multiprobe system has been upgraded to include a monochromated X-ray source which in conjunction with the high-resolution analyser should produce improved ability to resolve the chemical state of surface constituent atomic species. This could be particularly useful in the analysis of telluride and antimonide cathodes where incomplete reaction of the constituent species could significantly influence performance. The atomic force microscope has also been recommissioned giving access to surface topological information in the same vacuum environment. Finally, a new sample deposition chamber has been added which will allow additional deposition sources to be attached thus broadening the range of photocathode research that can be carried out.

Speaker: Tim Noakes (Science and Technology Facilities Council)

16:00 Analysis of laser-electron-radiation interaction in laser modulators for three SSMB scenarios

Recent studies explored a novel storage ring light source using steady-state microbunching (SSMB). Existing investigations predominantly focused on single-particle and pure-optics phenomena. Many SSMB schemes employ laser modulators, comprising an undulator and copropagating laser beam, to manipulate electron longitudinal bunch length. Electron bunch traversing the undulator emits coherent undulator radiation near the resonant wavelength. Laser beams may form a closed path to become a laser enhancement cavity. We developed a model* analyzing laser-electron-radiation interactions in laser modulator cavities, considering mirror-induced losses, externally injected laser power compensation, and coherent undulator radiation dynamics on multiple turns. Our approach integrates beamline transfer matrices with a low-gain FEL oscillator model, enabling quick estimation of the dynamic effects. In this work we examine three SSMB scenarios, amplifier, frequency-beating, and harmonic, accounting for laser-electron-radiation interactions. Under preliminary design parameters, our analysis suggests feasibility for the three scenarios. A potential self-seeding SSMB scheme is also investigated.

Speaker: Cheng-Ying Tsai (Huazhong University of Science and Technology)

16:00 Beam control and characterization of the new SLS 2.0 booster-to-ring transfer line

Off-axis top-up injection into 4th generation storage ring light sources is complicated due to the transverse acceptance, which is typically in the order of a few millimeters. Therefore, the characteristics and control of the incoming beam from the transfer line plays an important role in achieving successful injection. SLS 2.0, the storage ring upgrade of the Swiss Light Source, is among the facilities where precise knowledge and control of the injected beam is important, particularly due to the usage of emittance exchange in the booster synchrotron. Here we highlight the most important design aspects of the new SLS 2.0 booster-to-ring transfer line, including the nondispersive section for beam characterization and the double-corrector configuration allowing injection position and angle control. Furthermore, we present the first experience with quadrupole scans and stabilization of the injected beam.

Speaker: Jonas Kallestrup (Paul Scherrer Institute)

16:00 Beam results for the new super-conducting booster at Jefferson Lab

The performance results of a new super-conducting booster for the CEBAF injector at Jefferson Lab, could be of interest for other similar electron injectors. A recent addition of this new booster has provided us the ability to achieve a more adiabatic acceleration and therefore an improvement to the beam dynamics and beam brightness. It has also simplified the design and operation of the section of the injector responsible for accelerating the electron beam from a few hundred keV to several MeV (typically 6.7 MeV). The addition of the new booster was part of an upgrade to the CEBAF injector to improve the beam quality for future physics experiments with high sensitivity to beam quality. The booster consists of two cavities: a 2-cell cavity followed by a 7-cell cavity. This combination allows for a wide range of input electron beam energies, from 130 keV to more than 300 keV. In fact, during the last year, the booster was successfully operated with 140,180, and 200 keV input beam energies as the electron gun was being upgraded. This paper describes the new booster, presents beam optics data results from different beam studies, commissioning, and the physics quality beam operation.

Speaker: Reza Kazimi (Thomas Jefferson National Accelerator Facility)

16:00 Cathode insertion and transfer system for the LCLS-II-HE SRF Gun

A new QWR SRF electron gun has been designed as a low-emissivity light injector for LCLS-II-HE, and a prototype is currently being developed in collaboration between SLAC, FRIB, HZDR, and ANL. The new gun will use an HZDR-type cathode, which includes a cathode load-lock (cathode stalk) developed by FRIB and a complex cathode exchange system designed by HZDR. A dedicated alignment process allows the cathode to be precisely aligned to the axis of cathode stalk without touching the cathode plug itself, ensuring particle-free exchange. At the same time, a chamber system has been built to transfer one cathode from the clean room to the electron gun under a request clean environment.

Speaker: Rong Xiang (Helmholtz-Zentrum Dresden-Rossendorf)

16:00 Cherenkov waveguide design for THz production at the EuXFEL

The EuXFEL R&D project, STERN, aims to provide X-ray users with an accelerator-based THz source synchronized with the X-ray repetition rate. The main proposed THz generation method consists of electron beam wakefield excitation in Cherenkov waveguides. This work focuses on the design of a copper block that holds an array of waveguides to cover the radiation spectrum spanning from 300 GHz to 30 THz. These will include a variety of lengths and dielectric layer thicknesses to vary the spectral contents of the excited TM modes. Additionally, driving the wakefield generation process with an off-axis electron beam causes the excitation of HE modes, which are of great interest to the user community and add to the spectral content of the THz pulse. To further increase pulse energy, the implementation of radiation incouplers is analyzed, demonstrating the potential for capturing the electron beams self-field completely. Such wakefield structures offer a novel option for delivering versatile THz sources tailored to next-generation pump-probe experiments.

Speaker: Karel Peetermans (Deutsches Elektronen-Synchrotron DESY)

16:00 Coherent high-harmonic generation with laser-plasma beams

Active energy compression scheme enables generating laser-plasma accelerator electron beams with a small relative slice energy spread, of the order of 10 ppm. When modulated by a laser pulse, such beams can produce coherent radiation at very high, about 100-th harmonics of the modulation laser wavelength, which are hard to access by conventional techniques. The scheme has a potential of providing additional capabilities for future plasma-based facilities by generating stable, tunable, narrow-band radiation.

Speaker: Sergey Antipov (Deutsches Elektronen-Synchrotron DESY)

16:00 Commissioning of the SLS 2.0 machine protection system

The Swiss Light Source (SLS) at the Paul Scherrer Institute (PSI) was Switzerland’s first and only 3rd-generation light source. For the SLS 2.0 upgrade the old 2.4 GeV, 12-fold 3-bend achromat lattice with 5 nm horizontal emittance was decommissioned in September 2023 after 22 years of successful user operation. The new 2.7 GeV storage ring has a 12-fold 7-bend achromat lattice achieving 150 pm horizontal emittance. Injectors remain mostly unchanged: the 100 MeV linac feeds the 3 Hz booster synchrotron with extraction at 9 nm horizontal emittance and now 2.7 GeV to match the storage ring’s increased energy. Technical details and an overview of the SLS 2.0 commissioning are presented in separate contributions to this conference. This contribution focuses on the machine protection system challenges for the SLS 2.0*. These required the implementation of a sophisticated system including a fast beam dump kicker, dedicated beam dump, fast beam dump controller and a machine interlock system monitoring over 6000 signals. We discuss challenges encountered and lessons learned while commissioning this advanced machine protection system in parallel to commissioning of the new accelerator.

Speaker: Felix Armborst (Paul Scherrer Institute)

16:00 Comparison of direct laser acceleration performance using radially polarized near infrared and long-wave infrared lasers

Direct laser acceleration with radially polarized lasers is an intriguing variant of laser-based particle acceleration that potentially offers GeV/cm-level gradients while avoiding the instabilities and complex beam dynamics associated with plasma-based accelerators. Currently, the performance of this method is primarily limited by the difficulty of generating high-power radially polarized beams. We propose the use of CO2-based long-wave infrared (LWIR) lasers as a driver for direct laser acceleration, as the polarization insensitivity of the gain medium allows for higher peak powers, since amplification can occur after polarization conversion. Additionally, the larger waist sizes and pulse lengths associated with a longer wavelength can improve electron beam injection efficiency. By comparing acceleration simulations using a near-infrared laser and an LWIR laser, we show that the injection efficiency is indeed improved by up to an order of magnitude using the LWIR laser. Furthermore, we show that even sub-TW LWIR lasers can provide MeV-level energy gains. Thus, radially polarized LWIR lasers show significant promise as a driver of a direct laser-driven demonstration accelerator.

Speaker: Mikhail Polyanskiy (Brookhaven National Laboratory)

16:00 Conceptual design of a compact synchrotron for proton-and-helium therapy facility

In recent years, proton and heavy-ion therapy has become increasingly widespread in clinical applications, and has emerged as one of the important means for cancer treatment. The commonly used particle types for this therapy are protons and carbon ions. However, further research into the biological effect has found that helium ions have both high biological effectiveness and small penumbra characteristics, which enable more precise locate of the tumor while also effectively killing tumor cells. And the highest energy of the helium ions used in therapy is 235MeV/u. Therefore, the equipment size and cost required for helium ions therapy will be significantly less than that for carbon ions therapy. To this end, this paper proposes a design for a helium-ion therapy synchrotron that also possesses the capability for proton therapy. The design employs eight ultra-high field dipole magnets to achieve a compact envelope function. Additionally, the design incorporates both multi-turn painting injection and mismatched injection methods in two directions, significantly minimizing the use of bump magnets. This results in a highly compact accelerator structure.

Speaker: Yuxuan Yang (UVSOR Facility)

16:00 Courant-Snyder formalism for modeling, optimizing and simulating broadband THz radiation transport

In order to exploit the scientific potential of user-oriented accelerator facilities, it is necessary to provide adequate pump sources to enable pump-probe science. The EuXFEL R&D project, STERN, aims to equip X-ray users with an accelerator-based THz source matching the high repetition rate of the XFEL. The proposed THz radiation generation methods involve Cherenkov wakefield structures and diffraction radiation, aiming to produce a spectrum from 300 GHz to 30 THz. To enable experimental characterization, both broadband and narrowband pulses must be transported through a single beamline to a radiation-shielded laboratory. A major challenge has been the simulation, optimization and design of the STERN beamline. The OCELOT accelerator lattice optimizer is adapted for optical transport with mirrors substituting traditional focusing magnets. The performance is corroborated using a THz transport code that considers beam clipping and diffraction. The optimized beamline achieves efficient transport over 10 meters, maintaining over 75% source-to-end efficiency across the frequency range. This development marks a significant step forward in THz beamline design for advanced applications.

Speaker: Karel Peetermans (Deutsches Elektronen-Synchrotron DESY)

16:00 Cryogenic APPLE undulator development at Helmholtz-Zentrum Berlin

In order to achieve polarization control at tender photon energies at a medium energy light source, a cryogenic in-vacuum APPLE device is being developed at Helmholtz Zentrum Berlin. The project builds on the innovative design of the in-vacuum APPLE II IVUE32 also in development at HZB. The state of the magnet and mechanical design is presented, in addition to the expected spectral performance of the device upon installation in the BESSY II storage ring.

Speaker: Ed Rial (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 Current status of the linac system for Korea 4GSR

The development of a 4th-generation storage ring (4GSR)-based light source has been in progress in Korea since 2021, utilizing a linear accelerator (LINAC) and a booster ring as injection systems. The LINAC generates a 200 MeV electron beam using an RF photocathode gun. Electron bunches produced by a UV laser in the RF photocathode gun are focused by a solenoid magnet positioned between the gun and the first accelerating column to ensure initial focusing. The LINAC system comprises four accelerating columns.
To achieve proper beam focusing and matching to the LTB (Linac to Booster), nine quadrupole magnets are installed downstream of the second accelerating column. Energy for the RF gun and accelerating columns is supplied by two klystron-modulator systems. For stable energy delivery, klystron-modulator systems with a power capacity of 70 MW are employed, each regulated separately by dedicated LLRF-SSA (Low-Level RF and Solid-State Amplifier) feedback systems. Additional details will be provided in the presentation.

Speaker: Woo Jun Byeon (Pohang Accelerator Laboratory)

16:00 Deflecting cavity-based multifunctional longitudinal manipulator for CSR-mitigated bunch compression

A deflecting cavity is an interesting tool providing a coupling between transverse and longitudinal planes. Several methods employing deflecting cavities have been proposed to shape current profiles or adjust longitudinal chirp. Even, a method using deflecting cavities was recently proposed for imparting arbitrary correlation on the longitudinal phase space. In this work, we introduce an integrated deflecting cavity-based beam manipulator capable of simultaneously controlling three longitudinal properties: chirp, linearity, and current profile. This relatively compact system can provide a linearized longitudinal chirp for bunch compression without requiring linac phase control and harmonic linearizers. Also, it generates a current profile that flattens the CSR wake, thereby minimizing emittance growth caused by CSR. The presentation includes the working principle of the system and simulation results.

Speaker: Alex DeSimone (Northern Illinois University)

16:00 Design and simulation of sub-harmonic bunchers for beam bunching efficiency in PLS-II linac

Pohang Light Source-II (PLS-II) is a third-generation synchrotron light source operated by the Pohang Accelerator Laboratory (PAL) since 2012. This study was conducted as a preliminary investigation for upgrading the linac to improve the beam operation efficiency of PLS-II. In this system, beam bunching is initially performed using a pre-buncher operating at the same frequency. To achieve more efficient beam bunching, we considered sub-harmonic buncher (SHB). Two cavities with frequencies of 1 GHz and 500 MHz were designed and beam dynamics simulations were performed, taking into account the available installation space. By comparing the bunch length of beam and other beam parameters for each cavity, we confirmed that the SHB could improve injection efficiency compared to the pre-buncher.

Speaker: Chanmi Kim (Pohang Accelerator Laboratory)

16:00 Design of a compact electron linac for the X-ray based intraoperative radiotherapy

In order to fill the gap of X-ray intraoperative radiotherapy technology in China, an X-band standing wave electron linear accelerator with operating frequency of 9.3 GHz was designed for X-ray intraoperative radiotherapy equipment. Using electromagnetic simulation software and beam dynamics simulation software, the outlet energy of the accelerator is 50 keV , and the electron capture efficiency is 37.5 %. The first cavity is 10 mm long for the optimization of the electron beam energy spectrum, and the second cavity is 12 mm long for the electron beam acceleration. The microwave power is distributed to the two cavities respectively through the power divider and the coupler. There is no energy exchange between the two cavities.

Speaker: Hanlin Wan (Lanzhou University)

16:00 Design of a resonant slow extraction from the planned DESY IV booster synchrotron

The planned upgrade of the synchrotron light source at DESY, Hamburg will include an upgrade of the booster synchrotron. We discuss the considerations for the design of a slow resonant extraction from this future machine. The implementation of a bent crystal as a potential septum shadower and/or as a septumless option is considered.

Speaker: Edgar Cristopher Cortés García (Deutsches Elektronen-Synchrotron DESY)

16:00 Design studies on a kHz–MHz repetition rate pulsed muon source based on electron accelerator

Certain types of muon experiments, such as muon spin rotation techniques and muon lifetime measurements, require beams with repetition rates around 50 kHz for optimal statistical performance. However, existing facilities are limited to pulsed beams operating at 25-50 Hz or continuous beams, both constrained by the time structure of proton drivers. Despite ongoing efforts to optimize these proton time structures, significant limitations in flexibility persist.
This work introduces an alternative approach to muon production using high-repetition-rate (kHz-MHz) electron beams generated by superconducting linacs at XFEL facilities. This method provides unique temporal characteristics, promising substantial improvements in beam precision, flexibility, and experimental efficiency.
We present comprehensive particle tracking simulations for the design of a surface muon beamline and detailed Monte Carlo studies to optimize target materials and geometries. The results underscore 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.

Speaker: Yusuke Takeuchi (Shanghai Jiao Tong University)

16:00 Design study for a transverse deflecting cavity based de-chirper

A collaboration is underway to experimentally demonstrate a novel approach using deflecting cavities to control a particle beam’s longitudinal chirp. While a series of deflecting cavities produces negative chirp, the de-chirping process requires additional modification on the beamline. It has been known that inserting negative drift sections between TDCs enables de-chirping. While the original idea of negative drift requires a series of five quadrupole magnets, the experimental conditions cannot provide enough quadrupoles and space for them. Additionally, it is confirmed that a negative drift using three quadrupoles introduces a significant increase in beam size and emittance in one of the transverse planes. Thus, we propose a new method to enable de-chirping by inserting a series of three quadrupoles. Here, we form a negative identity transport instead of the negative drift. Simulations have been performed to explore this new opportunity. We present the result of this design study.

Speaker: Alex DeSimone (Northern Illinois University)

16:00 Design study of a THz SASE FEL at NSRRC

NSRRC has developed a superradiant terahertz (THz) free-electron laser (FEL) that utilizes a photoinjector operating in its velocity bunching mode. This system currently achieves a maximum THz frequency of 1.4 THz, constrained by the shortest electron bunch duration of 240 fsec attainable with the photoinjector. To extend the operation THz range to higher frequencies, we are exploring the potential of implementing a self-amplified spontaneous emission (SASE) FEL in the 3-30 THz regime. This approach is considered to be promising to overcome current frequency limitations and enable access to a broader spectrum of high-intensity THz radiation. In such setup, a dogleg bunch compressor will be installed after the photoinjector, and followed by a dielectric-lined waveguide dechirper to remove residual energy chirp left after bunch compression. The proposed THz SASE FEL is currently under simulation study and will be reported. This effort represents an exciting step forward in broadening the scope and applications of THz science and technology at NSRRC.

Speaker: Shan-You Teng (National Central Univeristy)

16:00 Development of a novel segmented THz-driven electron source

Scaling the RF-accelerator concept to terahertz (THz) frequencies possesses several compelling advantages, including compactness, intrinsic timing between the photoemission and driving field sources, and higher field gradients associated with the shorter THz wavelength and higher breakdown threshold promising vastly smaller and cost-efficient accelerators. These benefits, however, come at the cost of smaller dimensions and tighter tolerances which are challenging to reach in practice. Experiments to test and characterize a multi-layered structure easy-to-implement electron source with tunable interaction length powered by 2 × 100 µJ of twin single-cycle THz pulses predicted to produce 100 fC electron bunches with 100 keV energy, < 1 % energy spread, 0.01 - 0.07 mm mrad transverse emittance and a bunch duration of 20 − 40 fs are currently in progress. Besides the gun structure, the performance characteristics of the THz-driven electron source, including the generation of terahertz pulses, UV beam profile, coupling efficiency of the gun structure, electron beam dynamics, etc are discussed in detail. Such THz-based accelerator prototypes are not only promising as injectors for compact THz-based LINACs but also as a source for ultrafast electron diffraction experiments

Speaker: Reza Bazrafshan (Deutsches Elektronen-Synchrotron DESY)

16:00 Development of an achromatic spectrometer for a laser-wakefield-accelerator experiment

The large gradients of plasma-wakefield accelerators promise to shorten accelerators and reduce their financial and environmental costs. For such accelerators, a key challenge is the transport of beams with high divergence and energy spread. Achromatic optics is a potential solution that would allow staging of plasma accelerators without beam-quality degradation. For this, a nonlinear plasma lens* is being developped within the SPARTA** project. As a first application of this lens, we aim to implement an achromatic spectrometer for electron bunches produced by a laser-wakefield accelerator. We report on progress in designing such an experiment.

16:00 Development of electronic orbit stability monitoring and analysis system in the Taiwan Photon Source

The Taiwan Photon Source (TPS) storage ring features 172 strategically deployed Beam Position Monitors (BPMs) forming a high-precision electron orbit monitor-ing network. This paper presents an automated monitoring system that periodically extracts BPM data from the data-base and calculates standard deviations to quantify beam stability through statistical methods. The system employs a hierarchical filtering algorithm to identify BPMs with the highest standard deviations and generates analytical visualizations while tracking temporal trajectories of sig-nificantly varying BPMs. During the resolution of BPM electrode anomalous jumps, we developed and integrated a Q-value-based anomaly diagnostic method that effective-ly differentiates between BPM electrode anomalies and actual orbit variations. The system incorporates the LINE Bot API for real-time notification capabilities, establish-ing a comprehensive data acquisition-analysis-alert work-flow. Through its multi-level monitoring architecture, the system has successfully identified and resolved several critical issues affecting beam stability, including electrode abnormalities in BPM183 and BPM126, significantly enhancing source stability and providing users with more reliable beam quality assurance.

Speaker: Wei-Yu Lin (National Synchrotron Radiation Research Center)

16:00 Development of photo injector employing Yb fiber laser for stimulus super-radiant THz FEL

THz wave is wonderful prove for materials. Additionally new nonlinear phenomena are expected in spintronic devices if the peak electromagnetic field is greatly higher than 10 MV/cm (3.3 T/cm). Although coherent transition radiation from short bunches is intense, it is very difficult to exceed 10 MV/cm. However we found a possibility of which oscillator FEL reaches ~100 MV/cm employing a pre-bunched configuration.* On a test accelerator (t-ACTS), we are going to introduce a photo-cathode to increase the bunch charge and synchronize with round-trip frequency of an FEL optical resonator. Currently t-ACTS supplies a bunch-charge of 5 pC, whereas the goal is to increase it more than 50 pC for the pre-bunched FEL. Since the intensity of coherent radiation is basically proportional to the square of the charge per bunch, increase of the bunch charge is much effective. The laser system includes a Yb fiber laser oscillator (wavelength: 1047 nm), a multi-pass amplifier, and a fourth harmonic generation (262 nm). A target synchronization accuracy is within 1 deg at 2856 MHz. The assembly of the oscillator has almost completed, and a work for synchronization with RF is on the way.

Speaker: Hiroyuki Hama (Tohoku University)

16:00 Epitaxial growth of sodium potassium antimonide photocathodes

Multi-alkali antimonide photocathodes are selected as candidates for electron sources that can continuously generate electron beams with high average current, high bunch charge, and low emittance. Such electron sources are essential for the current electron cooling scheme in Electron Ion Collider (EIC) to cool the hadron beams and maintain beam luminosity. In BNL, epitaxial growth of multi-alkali antimonide photocathodes on lattice-matched substrates are investigated to achieve improved photocathode properties and performances. In this work, epitaxial growth of Na-K-Sb is reported and characterized by reflection high energy electron diffraction (RHEED). Spectral response of the epitaxial Na-K-Sb photocathodes along with lifetime tests are conducted and reported.

Speaker: Mengjia Gaowei (Brookhaven National Laboratory)

16:00 EPU coupling correction by Bayesian optimization in TPS

APPLE-II type elliptically polarized undulators (EPUs) are critical for producing elliptically polarized light in modern synchrotron light sources. However, residual skew quadrupole components from manufacturing imperfections can couple horizontal betatron motion and dispersion to the vertical plane, changing beam size and degraded beam quality. This paper introduces a Bayesian optimization-based approach to correct these coupling effects for EPU66 at the Taiwan Photon Source (TPS). By constructing a two-dimensional coupling feed-forward table as a function of EPU gap and phase. Experimental implementation and verification with the closest-tune approach demonstrate the efficacy of this method. This article details the optimization process, mathematical framework, and experimental results, establishing a practical strategy for EPU coupling correction in TPS.

Speaker: Mr Mau-Sen Chiu (National Synchrotron Radiation Research Center)

16:00 Exploring the feasibility of a few pico-Coulomb, nanometer-emittance operation at Argonne Wakefield Accelerator Facility

We present an injector simulation study to explore the feasibility of a few pico-Coulombs with nanometer-emittance operation at the Argonne Wakefield Accelerator (AWA) facility. The accelerator community have utilized or explored pico-Coulomb or even lower charges to achieve a nanometer level emittance for various applications such as ultrafast electron diffraction, attosecond pulse generation, and nanometer scale longitudinal bunch train generation. Combining such nanometer-emittance bunches with an emittance exchange beamline at the AWA facility would enable research opportunities utilizing attosecond bunches or nanometer-scale longitudinal bunch trains. While the primary focus of this study is demonstrating feasibility, we also provide preliminary simulations related to nanometer-scale longitudinal bunch train.

Speaker: Spencer Kelham (Northern Illinois University)

16:00 Feasibility study of a THz beamline design for the THz user facility at NSRRC

Feasibility design of THz beamlines for the use of the superradiant THz free electron laser driven by the NSRRC high brightness photo-injector has been studied. The Accelerator Test Area (ATA) building, where the photo-injector installed, will be transformed into a THz user facility that meets radiation safety regulations. Narrow-band intense superradiant THz radiations with pulse energy as high as 20 μJ and tunable central frequency from 0.6 to 1.4 THz, generated by injecting an ultrashort electron beam into a U100 planar undulator, can be a useful tool for nonlinear and time-resolved pump-probe experiments. There will be two stages for user experiments. Phase I will be opened for users with the experimental station installed right after the THz sources in the accelerator tunnel. Another THz beamline, which is currently being designed to maintain the quality of THz radiations after propagation over longer distances, will be built for user experiments in Phase II. This report briefly describes the beamline design and the operation of user experiments in Phase I.

Speaker: Ming-Chang Chou (National Synchrotron Radiation Research Center)

16:00 Field emission and unwanted beam propagation simulations in the SRF gun at SEALab

The ideal beam coming from an RF photoemission electron gun is composed only of electrons that are produced by the incidence of the drive laser in the photocathode. The timing of the drive laser with respect to the RF fields in the gun is carefully chosen to tailor the beam properties. There are, however, sources of unwanted electrons that degrade the performance of RF photoemission guns. Field emission in superconducting radio-frequency (SRF) guns contributes to unwanted electron generation, known as dark current. This work presents simulations based on the Fowler–Nordheim (FN) model~\cite{FN} to study field emission in the SEALab SRF gun cavity. By analyzing 2D field maps and using ASTRA simulations~\cite{Astra}, emission hotspots are identified, and particle trajectories are evaluated. While most field-emitted electrons are lost within the cavity, a small but significant portion escapes, contributing up to 25\% of the emitted power. The analysis offers key insights into mitigating performance-limiting effects in SRF guns.

Speaker: Benat Alberdi-Esuain (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 Finalizing the multiphysics design of a high heat-load superconducting undulator

RadiaBeam is developing and manufacturing a 15mm period, high temperature superconductor undulator using Magnesium Diboride (MgB2) wire at 10K-15K temperature range. This temperature range can be achieved by cryocooler, a simpler and less expensive cryogenic solution compared to a liquid helium approach. After optimizing the thermal-mechanical design, the operating temperature is finalized at 7K. We examine the current density, critical field, tensile stress, tensile strain, and temperature of MgB2 wire in multiphysics approach and determine the operating field to be 1.13T with safety margin. A quench-protected power system is developed for training the SCU to the operating point in controlled ramp rate. The SCU will be characterized by in-vacuum pulse wire measurement system.

Speaker: Yung-Chuan Chen (RadiaBeam Technologies (United States))

16:00 First magnetic experience with APPLE X knot undulators for SLS 2.0

The next generation of synchrotrons will have undulators with shorter periods, stronger magnetic fields, and thus higher radiation power. Consequently, concepts for reducing on-axis heat load will become more relevant. One possible idea is to introduce so-called APPLE “knot” undulators that shift the main energy peak off-axis. Thanks to almost on-axis injection, APPLE X undulators with a round vacuum chamber can be used for the upgraded SLS 2.0 at the Paul Scherrer Institute (PSI). This contribution presents an adaptation of the APPLE “knot” concept tailored to the needs of SLS 2.0 in the form of two-meter-long APPLE X undulators with a 36 mm period length and a gap of 11.5 mm. Our design faces the challenge of dealing with up to 16 different magnetization angles introduced by combining and merging NdFeB magnets into four arrays with peak fields around 1 T. Consequently, the magnetic design and the first measurement results are discussed with an outlook on magnet optimization.

Speaker: Sebastian Richter (Paul Scherrer Institute)

16:00 First THz light generated in high energy section of FLUTE

FLUTE is a compact and flexible linac-based accelerator test facility at the Karlsruhe Institute of Technology (KIT) in Germany. It serves as a platform for a variety of accelerator studies and to generate intense short THz pulses for various photon science experiments. Later, FLUTE will be also used as an injector of sub-100 fs bunches into the VLA-cSR (Very Large Acceptance compact Storage Ring), which is part of the cSTART (compact STorage Ring for Accelerator Research and Technology) project currently in the technical design phase at KIT.
Recently, FLUTE's high energy section has been installed and commissioned. This includes the linac, bringing FLUTE beyond 5 MeV to full energy, the bunch compressor, and two corresponding diagnostics sections. A metal foil in the last diagnostics section has been used to generate a first THz signal with high energy electron bunches.

Speaker: Michael Nasse (Karlsruhe Institute of Technology)

16:00 Front end developments of the ESS Linac

The ion source at the European Spallation Source (ESS) since its comissioning in 2019 continues to support the beam commissioning phases of the Linac. In order enable comprehensive characterisation and benchmarking of the ion source's performance, as well as to facilitate future upgrades, a dedicated test stand has been constructed and is nearing completion. This test stand features an ion source identical to the one installed in the operational machine, allowing for detailed performance evaluation independent of the operational machine.
The Low-Energy Beam Transport (LEBT) section of the Linac includes the microwave-discharge ion source, solenoid magnets, beam diagnostics, and an iris for beam current regulation, for which a new iris design was developed. This paper presents the design considerations, thermo-mechanical simulations, and preliminary testing results from the ESS Ion Source Test Stand. These efforts aim to enhance the understanding of the ion source's operational behavior, guide future improvements and upgrades, and ensure the continual optimization of the ESS Linac’s long-term performance

Speaker: Domenic Nicosia (European Spallation Source)

16:00 How can electrons be accelerated by a longitudinal wake field excited in a plasma?

Abstract
The possibility of charged particle acceleration by a longitudinal wake field excited in plasma by an electron bunch and a train of electron bunches is investigated. The exact solution of the stationary nonlinear self-consistent interaction of a monoenergetic relativistic bunch with cold plasma is obtained. It is shown that under certain conditions a self-acceleration of the bunch tail electrons up to high energies is possible.

Speaker: Koryun Oganesyan (A. Alikhanyan National Laboratory)

16:00 Initial characterization of a laser-driven betatron radiation source in the EuAPS project

Betatron radiation is the spontaneous emission of radiation produced by the betatron oscillations of electrons in a plasma during the Laser Wakefield Acceleration (LWFA) process. A high-intensity and ultra-short laser pulse is focused on a supersonic gas jet, simultaneously creating a plasma, injecting, and accelerating electrons, which then emit this radiation. In the framework of the EuPRAXIA project, EuAPS (EuPRAXIA Advanced Photon Source) will be the first user-oriented radiation source based on betatron radiation developed at LNF-INFN Frascati in collaboration with CNR and the University of Rome Tor Vergata.
This radiation source has a wide range of applications, including materials science, medical and biological research. The user facility aims to deliver 1-10 keV photons using a compact laser-driven plasma accelerator operating in a self-injection mechanism, which occurs in highly nonlinear laser-plasma interaction. In this contribution, we present the expected parameters of the source and the result of several dedicated experimental campaigns conducted within the EuAPS project to provide the preliminary characterization of the x-rays betatron radiation source.

Speaker: Federica Stocchi (Istituto Nazionale di Fisica Nucleare)

16:00 Latest dark current studies of RF photocathode gun of Delhi Light Source

The Delhi Light source is a pre-bunched Free Electron Laser facility to generate coherent THz radiation. The electron beam is generated from a normal conducting 2.6 cell RF photocathode (PC) gun operated at 2860 MHz. The RF gun is powered by a high power RF source for a duration of 4 µs at 10 Hz repetition rate. The dark current during the operation of the RF gun has been found to be substantially high with increasing forward powers (above 3 MW) even after prolonged RF conditioning. Dark current measurements has been done with an in-house developed faraday cup with an objective to understand the possible primary dark current source from locations at the PC that witnesses high accelerating fields. The measurements include the study of solenoid field variation to understand the dark current energies and effect of its steering to understand the possible dark current locations. Simulations to make inference from the measurements has been done assuming different radial position of dark current emitters at the PC surface. The details of the measurements, simulation results and the inference drawn are discussed in the paper.

Speaker: Joydeep Karmakar (Guru Ghasidas Vishwavidyalaya)

16:00 LCLS-II photo-injector operational challenges and developments

LCLS-II has turned into users operations since 2023 and has gradually ramped the beam rate to 16kHz to date. LCLS-II photoinjector has demonstrated low emittance beam operating at high rate. During operation, we also experienced challenges such as charge production and FEL intensity dependence to the beam rate, beam split, and emittance growth due to unexpected nonlinear field. These problems are addressed through systematic studies. Recently, the over-inserted Cs2Te photocathode has been developed and installed in the LCLS-II gun for significant dark current reduction and emittance improvement. This paper is to discuss LCLS-II photoinjector's ultra-low emittance operational challenges and developments with tens of kHz beam rate as well as the first measurements of the dark current and emittance with the over-inserted photocathodes.

Speaker: Feng Zhou (SLAC National Accelerator Laboratory)

16:00 Linac gun driver for the Swiss Light Source 2.0

The Paul Scherrer Institute has developed advanced Linac gun driver electronics designed for use in Linear Accelerators, particularly for modern Synchrotron Light Sources. A prototype of this innovative gun driver was successfully evaluated during the final three months of user operations at the Swiss Light Source (SLS). The finalized design is now installed and will be integrated into the upgraded SLS 2.0, which is scheduled to undergo commissioning in 2025.
The new gun driver is engineered to achieve extremely short electron bunch lengths, a key requirement for SLS 2.0 top-up operations. It delivers single pulses with the following specifications: 80 ps fall-time, 120 ps FWHM, and a -300 V peak amplitude, with a jitter of less than 5 ps.
These enhanced performance parameters will facilitate a future redesign of the SLS Linac, making it more compact while further improving its functionality.
This presentation will outline the implementation of the new gun driver and showcase the results obtained during its evaluation.

Speaker: Marcos Gaspar (Paul Scherrer Institute)

16:00 Low-temperature and strained-lattice effects on Monte Carlo modeling of spin-polarized photoemission from GaAs

The degree of spin-polarization of electrons photoemitted from unstrained, room-temperature GaAs is usually significantly less than the theoretical maximum of 50%. However, it has been experimentally observed that the degree of electron spin polarization can be increased and even exceed the theoretical maximum when the sample is cooled to low temperatures and in strained-lattice samples. The previously developed Monte Carlo approach to spin-polarized photoemission from unstrained, room temperature NEA GaAs provides excellent agreement with experimental data in a wide range of doping densities and photoexcitation energies. This work aims to extend the model’s capabilities by incorporating both low-temperature and strained-lattice effects into the band structure and investigating their impact on spin and momentum relaxation mechanisms. Modeling of both low-temperature and strained NEA GaAs with the use of parameters obtained via Density Functional Theory (DFT) calculations will provide a foundation for modeling photoemission from novel spin-polarized materials and complex layered structures and aid in the discovery of new cathode materials.

Speaker: John Callahan (Northern Illinois University)

16:00 Molecular beam epitaxial growth of Sodium Antimonide photocathodes

Cornell University has been working on developing techniques to grow single crystal photocathodes for electron sources using the Molecular Beam Epitaxy (MBE) technique. As a result, the first single crystal Cs3Sb photocathode was produced, which has shown high quantum efficiency and is expected to have a low Mean Transverse Energy (MTE). Now, other alkali materials are being explored. In this work, we report the epitaxial growth of Na-Sb photocathodes at the PHOtocathode Epitaxy Beam Experiments (PHOEBE) laboratory at Cornell University, employing a sequence of shuttered growth steps to form distinct unit cells. The photocathodes were characterized by Quantum Efficiency (QE) measurements and Reflection High-Energy Electron Diffraction (RHEED) patterns collected during growth. The RHEED streaky pattern shows angle dependence, confirming their single crystal structure. Notably, these Na-Sb photocathodes exhibited a QE exceeding 1% at 400 nm, which is much higher than previous reports on this compound. The possible reasons for this discrepancy are discussed.

Speaker: Abigail Flint (Cornell University (CLASSE))

16:00 Nb3Sn superconducting multipole wiggler as a vertically polarized hard X-ray source

Vertically polarized superconducting wigglers enable unique hard X-ray experiments based on horizontal optical setups. However, their implementation in modern low-emittance storage rings has been limited due to significant emittance growth. We present a vertically polarized superconducting multipole wiggler designed to reduce the impact on beam emittance. By limiting the magnetic field to 2-3 T and shortening the period length using Nb3Sn wires with higher critical current density compared to conventional NbTi, the beam orbit amplitude and the resultant emittance growth are reduced. As a case study for the future light source project at KEK, PF-HLS (Photon Factory Hybrid Light Source), we discuss a design based on vertical circular winding coils with a sub-100 millimeter period length and a sub-100 micrometer orbit amplitude, as well as its influence on beam emittance.

Speaker: Hirotoshi Saito (High Energy Accelerator Research Organization)

16:00 New compact modular in-vacuum undulators for SLS 2.0

A new design for in-vacuum undulators has been developed for the upgraded SLS 2.0 at the Paul Scherrer Institute (PSI), combining several new, beneficial concepts: modular, compact construction, integrated keepers for automated field optimization, and magnetic force compensation. This enables a scalable and relatively lightweight realization. The basis is solid aluminum vacuum chamber modules capable of handling the forces, replacing the classic bulky support. These 50 cm-long modules are connected on girders up to the desired length. A wedge-based drive, operated selectively by a hydraulic or an electrical system, adjusts the gap. The magnetic forces are compensated in the keeper, where the magnets are adjustable via flexor elements, facilitating automated field optimization.
This contribution shows the status by presenting measurements and optimization results of our new design, currently realized at PSI, employing a hydraulic drive system for a one-meter-long undulator with a period length of 15 mm. Furthermore, an outlook is given on the manufacturing of such three-meter-long undulators using NdFeB with a period length of 17 mm and 1.2 T maximum field amplitude at a 4 mm gap.

Speaker: Sebastian Richter (Paul Scherrer Institute)

16:00 New developments in the design of the muon production target area of a multi-TeV muon collider

As the International Muon Collider Collaboration advances the conceptual design for a multi-TeV muon collider facility, new technical constraints continue to arise in the muon production stage, where a high-power proton beam interacts with a target. Achieving the required muon bunch intensity may necessitate increasing the primary beam power up to 4 MW. Consequently, the shielding design must address sustained radiation exposure, particularly on critical components such as superconducting solenoids, which generate strong magnetic fields essential for capturing both pions and decay muons. Additionally, the portion of the proton beam that passes through the target without undergoing inelastic interaction leads to a very high power density in the chicane area and an intense ionising dose on the insulation material of the normal-conducting chicane magnets, which are used to separate the muon component. A robust method to safely extract these spent protons is crucial. This study presents the latest results from FLUKA Monte Carlo simulations, modelling the radiation load on solenoids and the extraction channel across varying beam power and target designs.

Speaker: Dr Jerzy Manczak (European Organization for Nuclear Research)

16:00 Performance of terahertz-wave beamlines at Nihon University's laboratory LEBRA

National Institute of Advanced Industrial Science and Technology (AIST) has collaborated with Nihon University to study generation of high-intensity terahertz waves using coherent radiations at the Laboratory for Electron Beam Research and Application (LEBRA) at Nihon University. In a straight section for parametric X-ray (PXR) generation, developments of various types of coherent radiation sources and a study of superimposed coherent radiation using a ring-type resonator have been conducted. Coherent edge radiation (CER) generated in the downstream bending magnet is transported to an experimental room using the PXR beamline and is used for spectroscopic measurements and imaging experiments in an acrylic box filled with dry air. In a straight section for an infrared free-electron laser (FEL), CER generated by a downstream bending magnet during FEL oscillations is extracted from an FEL resonator by a toroidal mirror with a hole.* The extracted CER is reflected by a sapphire substrate coated with Indium-tin oxide and transported to the room using an FEL beamline.
In this presentation, the status of the two THz beamlines at Nihon University's laboratory LEBRA will be described.

Speaker: Norihiro Sei (National Institute of Advanced Industrial Science and Technology)

16:00 Performances of a dual-axis radiographic diagnostic for hydrotest

Since 2023, the hydrotest Epure facility, located at Valduc, Burgundy, operates as a dual-axis radiographic system for French and British nuclear deterrence programs.
Each of the two axes is a single pulse electron linear induction accelerator rated nominally at 20MeV, 2kA and driving an X-ray conversion target. The first one is in use since 2013 at Valduc, and the other since 2023. Both share many traits and design features.
We tested each one under a range of operating parameters, mainly current for the one and energy for the other. We assessed performances in terms of X-ray output, beam stability and reliability and evaluated coherence between different diagnostics, including between X-ray detectors and electrical monitors, and between electrical monitors.

Speaker: Ludivine Mercier (CEA Valduc)

16:00 Physics design of linear accelerator for S3FEL

Shenzhen Superconducting Soft X-Ray Free Electron Laser (S3FEL), a continuous-wave superconducting facility aimed at providing soft X-ray FEL pulses with a repetition rate of 1 MHz, is currently under construction. These FEL pulses originate from the electron beam generated in a superconducting linear accelerator (linac). This paper comprehensively describes the physics design of the linac, detailing the determination of the longitudinal working point, the optimization of the transverse lattice, and also the particle tracking simulation. Additionally, this paper presents a detailed summary of the linac beam performance.

Speaker: Zhenbiao Sun (Institute of Advanced Science Facilities, Shenzhen)

16:00 Preliminary studies for a high gradient 6GeV injector linac for EBS

The ESRF mid-term plan for the upgrade of the injection complex foresees a full energy linac option. Given the space limitations of the site, compactness is a strong design constraint and high gradient technology is a potential candidate to fulfill this goal. Beam dynamics simulations have been performed for several different accelerating structures in the S-, C- and X-band frequencies to define the best candidate.

Speaker: Nicola Carmignani (European Synchrotron Radiation Facility)

16:00 Progress of polarized sources at BNL

The Optically Pumped Polarized Ion Source (OPPIS) has been providing polarized H- ions to the injector chain of the Relativistic Heavy Ion Collider (RHIC) since 2000. The OPPIS has undergone several upgrades. The latest upgrade, completed in 2022, included several improvements. Optimizing the Rb and Na cells has mitigated vapor dispersion in the beamline, resulting in a significant reduction of Rb and Na consumption and enhanced source stability. Modifications substantial increase in the lifetime of source.The upgrades confirmed reliable operation, with a mean current of 350 µA and an average polarization of 80% effectively provided at the end of the 200 MeV linac.
We are also developing a high-intensity 3He++ polarized ion source for the future Electron-Ion Collider (EIC). This source will utilize a new technique based on the polarization of accumulated high-purity 3He gas in a high magnetic field through metastability-exchange optical pumping. The existing Electron Beam Ion Source (EBIS) will then ionize the polarized gas using its electron beam. We have developed an infrared laser system for both pumping and measurement within the high-field environment of the EBIS.

Speaker: Deepak Raparia (Brookhaven National Laboratory)

16:00 Progress of SUNDAE2 magnetic measurement setup for superconducting undulators at European XFEL

At European XFEL up to six superconducting undulators with 18 mm period and 1.83 T magnetic field are planned to enlarge the hard X-ray photon range above 30 keV. Currently, S-PRESSO, a prototype with 2x 2m long undulator sections plus phase shifter in a 5m long cryostat is being produced.
The SUNDAE2 (Superconducting UNDulAtor Experiment 2) magnetic field test facility aims to perform in-vacuum magnetic field measurements of superconducting undulators (SCUs). This work provides an update on the progress of SUNDAE2, which employs Hall probe, moving wire, and pulsed wire techniques for precise magnetic field characterization to meet the specifications for the FEL operation.

Speaker: Thomas Schmidt (Paul Scherrer Institute)

16:00 Progress on emittance exchange-based nano-modulation generation

An emittance exchange (EEX) beamline may provide a unique capability in transferring a transverse beam density modulation into longitudinal bunching. This process can be advantageous for generating coherent radiation below the micron level, through super-radiant emission in a radiating system, or by providing a large input  signal for a high gain FEL. Indeed, this mechanism has been proposed to enable FEL action down to the few nm scale for a future facility now under construction at ASU. We investigate the feasibility of creating longitudinal density modulation at the Argonne Wakefield Accelerator, beginning with 800 nm bunching in a pC-level beam. We discuss plans for modulated beam creation, also addressing collective and nonlinear effects in the EEX beamline and subsequent radiation-based diagnosis via CTR or FEL processes.

Speaker: Aliaksei Halavanau (SLAC National Accelerator Laboratory)

16:00 Progress towards kick and cancel injection for Diamond-II

With the aim of maintaining transparent and efficient injection during top-up, a kick-and-cancel injection scheme has been developed for Diamond-II. In this, stripline kickers are used with 3 ns pulses to deflect individual bunches, with the stored bunch receiving two kicks separated by 180 degrees phase advance to leave it on-axis and the injected bunch timed to arrive at the second kick. In this paper we present progress with the hardware design and recent prototyping results, alongside updates to the simulations.

Speaker: Ian Martin (Diamond Light Source)

16:00 Recommissioning of the University of Hawai‘i LINAC and Free Electron Laser

The electron beam linear accelerator (linac) at the free-electron-laser (FEL) laboratory of the University of Hawai‘i at Mānoa, originally developed by Prof. John Madey, has undergone recommissioning. The S-band linac delivers 45 MeV electron beams with 170 mA pulse current and 4–8 $\mu$s pulse duration to drive an infrared FEL oscillator. Recent efforts include restoration of the microwave thermionic gun with a new LaB$_6$ cathode, upgraded vacuum and RF systems, and development of a Python-based beam dynamics model to recover operational magnet settings and optimize beam transport. These upgrades address key technical challenges to restart the accelerator and pave the way for future FEL experiments, including coherent pulse shaping and inverse Compton scattering x-ray generation.

16:00 Refined FLUKA simulation model of neutrino-induced effective dose from a multi-TeV muon collider

Most muons injected into a muon collider decay into an electron (or positron) and a neutrino-antineutrino pair, producing a narrow disk of high-energy neutrinos emitted tangentially to the beam in the collider plane. These neutrinos reach the Earth’s surface at distances far away from the collider. Vertical diffusion of the neutrino cone, reducing integrated neutrino flux at any surface exit point, has been proposed as mitigation technique. This study presents effective dose calculations performed with the FLUKA Monte Carlo code for various geometrical models, each representing conservative radiation exposure scenarios from neutrino flux emerging from the ground at specific distances from muon decay points. These scenarios correspond to different parts of the muon collider ring: bending sections and long straight sections housing experiments. Results are provided as effective doses for annual exposure scenarios with a 100% occupancy. Two muon beam energies are considered: 1.5 TeV and 5 TeV, with a more detailed approach applied to the higher energy.

Speaker: Dr Jerzy Manczak (European Organization for Nuclear Research)

16:00 Return of experience in the commissioning of the new CLS LINAC injector

After more than 40 years of services the 2856~MHz linac injector of The Canadian Light Source (CLS) has been retired to leave space for a new 3000.24~MHz linac injector, the frequency of which is a multiple of the 500.04~MHz CESR-B type superconductive radio frequency cavity. The new CLS linac injector has been designed and built by RI Research Instruments GmbH. The design is based on their robust S-band technology RF structures that already serve other laboratories in the USA, Australia, Taiwan, Switzerland and Sweden. In order to save money and space the CLS has replaced its six long Accelerating RF structures (3.4~m long) delivering 250~MeV electron beam by three 5~m long accelerating structures that will deliver the same beam energy. In order to do so, one RF structure is powered by one modulator-klystron and the last two RF structures received their RF power from a second modulator-klystron that passes through a SLED system. The SLED system multiplies the power by a factor 5 to 6 and is then equally split to power each structure. We are reporting on the progress of the commissioning of this new injector.

Speaker: Frédéric Le Pimpec (Canadian Light Source (Canada))

16:00 RF and synchronization system for VEGA project

The Variable Energy Gamma (VEGA) system is under implementation in Bucharest-Magurele (Romania) as one of the major components in the project of Extreme Light Infrastructure Nuclear Physics (ELI-NP). Photon beams will be resulting from the Inverse Compton Scattering of laser photons off relativistic electrons. VEGA is dedicated for photonuclear research both in applied and fundamental physics and will be open for worldwide users.
The RF and synch system has to ensure stable, synchronized and coherent operation of all RF pulsed devices. It plays a crucial role in the overall performance of the particle accelerator and ultimately the beam quality. This paper presents the LLRF and synch system for the VEGA electron linac. It is based on commercial S-band Libera products from Instrumentation Technologies (Slovenia). Experience with its operation, tests results of key performance parameters and the current operational status together with plans for future upgrade are presented. Likewise the HLRF system for the RF photocathode gun and the TW cavities, based on klystrons followed by SLEDs and hybrid power dividers, is described here. Also the phase tuning of the RF cavities is discussed.

Speaker: Piotr Tracz (Horia Hulubei National Institute for R and D in Physics and Nuclear Engineering)

16:00 Simulation and developmental status for generation and detection of THz using coherent transition radiation technique in Delhi Light Source

THz technology being a highly growing and potent field, finds use in a wide range of research applications. Delhi Light Source (DLS) at IUAC, New Delhi is at final stage of commissioning to produce intense and coherent THz radiation based on pre-bunched Free Electron Laser principle. As an addition to the narrowband undulator radiation, broadband Coherent Transition Radiation (CTR) will also be produced by passing femtosecond electron beam bunches through an Al foil . To generate the electron bunches with multi-micro bunch structure from the RF photo cathode gun, a state of the art femtosecond fiber laser system has been developed in collaboration with KEK, Japan. The generated electron beam bunches with energy up to 8 MeV is expected to produce CTR maximum up to few microjoule of energy. The multi-micro bunch structure increases the average CTR power. This paper reports the simulation results of the CTR showing the power, angular and frequency distribution produced from DLS facility. The schematic design and developmental status of DLS for generation and detection of THz CTR are also discussed.

Speaker: Bappa Karmakar (Inter-University Accelerator Centre)

16:00 Simulation and optimization of nonlinear kicker injection for PAL-EUV storage ring

The PAL-EUV storage ring has been designed to provide extreme ultra violet (EUV) beams, and is currently under commissioning. With a circumference of 36 m and an electron beam energy of 400 MeV, injection from the booster to the ring is achieved using a nonlinear kicker. Successful injection requires precise tuning of the kicker’s timing delay and maximum strength to match the injected beam’s conditions. This paper investigates the optimization method for these parameters and presents the results obtained through simulation.

Speaker: Gyeongsu Jang (Pohang University of Science and Technology)

16:00 Simulation study of beam-driven plasma wakefield experiments on CLARA

The Compact Linear Accelerator for Research and Applications (CLARA) is an electron test facility capable of delivering tunable 250 MeV electron beams with up to 250 pC charge to the Full Energy Beam Exploitation (FEBE) experimental area . In this study, we investigate the feasibility of conducting beam-driven plasma wakefield acceleration (PWFA) experiments using the CLARA beam and experimental area. We present simulations of various potential experiments, considering the baseline and R&D beam parameters expected to be delivered to the FEBE experimental chambers*. Our findings highlight the potential for CLARA to support advanced PWFA research, with detailed analysis of beam dynamics and experimental configurations.

Speaker: Toby Overton (Science and Technology Facilities Council)

16:00 Simulation study of nanostructured plasmonic copper photocathodes

We present an electromagnetic characterization and beam dynamics study of nanostructured plasmonic copper photocathodes for electron gun applications. The study concentrates on photocathodes operated at ultraviolet and infrared wavelengths. Various types of nanopatterns are explored in order to understand how different geometrical parameters affect light reflectance. Optimized nanostructure geometries show significant plasmonic field enhancement, leading to improved photon absorption and increased quantum efficiency at the target laser wavelength. The results of electromagnetic simulation are used to obtain quantum efficiency spatial distribution on the structured cathode surface. The resulting distribution is used for optically induced emission simulation. Beam dynamics simulation results of the photoemitted electron bunch in the vicinity of the nanostructured cathode are presented, analyzed, and compared to those of a flat photocathode.

Speaker: Margarita Bulgacheva (Technical University of Darmstadt)

16:00 Simulations and experimental commissioning results of the AWAKE Run 2 photoinjector

AWAKE (Advanced Wakefield Experiment) is the world’s first proton-driven plasma wake field acceleration experiment and has demonstrated the acceleration of electrons to several GeV’s in its first Run. The goal of Run2 is acceleration of a witness bunch whilst preserving beam quality and experiment scalability. AWAKE drives high gradient plasma wake fields using a proton beam, then a secondary electron beam is accelerated which is externally injected from a dedicated injector which consists of an S-band Rf-gun and an X-band bunching and acceleration system. This S band RF-Photoinjector for the AWAKE Run 2 experiment at CERN is currently being commissioned. The obtained experimental results are presented and compared to simulations in this paper.
Overall, the commissioning demonstrates successful matching of beam parameters with the design values, supported by ASTRA simulations. This lays the groundwork for low emittance electron beam injection into the AWAKE plasma and opens possibilities for future high-gradient acceleration experiments.

Speaker: Anton Eager (European Organization for Nuclear Research)

16:00 Simulations of transverse dynamics in a laser-plasma accelerator

Laser Wakefield Accelerators (LWFA) offer a promising solution for producing high-energy electron beams in compact setups. Beyond obtaining the required energy, the beam quality (emittance, energy spread, intensity) must also be optimized for LWFA to be considered an alternative to conventional accelerators. Achieving precise control of the transverse beam dynamics is one of the key challenges. This article thoroughly studies the physics governing the evolution of emittance and Twiss parameters within the plasma stage, on the density plateau, and in the up-ramp and down-ramp connections to conventional transport lines. Analytical and numerical analysis will be conducted using a toy model made of special quadrupoles, allowing numerical calculations to be sped up to a few seconds/minutes. Matching between plasma and transport lines will be extensively studied, clearly showing the dependence on initial conditions, and recommendations for the best realistic configurations will be provided*.

Speaker: Laury Batista (Commissariat à l'Énergie Atomique et aux Énergies Alternatives)

16:00 Six-dimensional phase space reconstruction with multimodal CNN

The information on phase space in all six dimensions is required for various accelerator experiments. We developed an algorithm based on Convolutional Neural Network (CNN) that can be used instead of the traditional back projection techniques because it is less computationally intensive and has a simple architecture. Our method has shown consistency with the simulation, and we plan to validate it on data taken at the KEK–Superconducting Test Facility (STF).

Speaker: Sayantan Mukherjee (Hiroshima University)

16:00 Specification of insertion devices for ORION project at SIRIUS

The pioneering ORION project will integrate a biosafety level 4 (BSL-4) laboratory with the SIRIUS synchrotron light source. The project includes three beamlines: TIMBÓ, HIBISCO, and SIBIPIRUNA, optimized for X-ray microscopy on biological materials. This study focused on evaluating Insertion Devices (IDs) for the TIMBÓ and HIBISCO beamlines, which demand high photon flux in the ranges of 3–20 keV and 16-40 keV, respectively. Achieving high photon energies with undulators in a 3 GeV synchrotron poses significant challenges. To address this, radiation emission calculations were performed for three ID types: in-air (IAU), in-vacuum (IVU), and cryogenically cooled permanent magnet (CPMU) undulators. With a numerical method based on SPECTRA* software, CPMUs were identified as optimal: a 2 m CPMU with a 14.6 mm period was identified for TIMBÓ, while HIBISCO ideal option is a 2 m CPMU with a 13.6 mm period. As a comparison of the types found for HIBISCO at 40 keV, CPMUs demonstrated approximately a 2.7x flux gain compared to IVUs, and IVUs about 3.8x the flux of IAUs. Further evaluations will consider also the impact on the electron beam dynamics and fabrication feasibility.

Speaker: Gabriel Ascenção (Brazilian Synchrotron Light Laboratory)

16:00 Spectrum-based alignment of SIRIUS undulators

Recently, two SIRIUS beamlines, EMA and PAINEIRA, received their definitive insertion devices (IDs). Both IDs are in-vacuum devices (IVUs), the first of this kind at SIRIUS. Due to the proximity of the IVU cassettes to the electron beam, the spectrum emitted by these devices is highly sensitive to misalignments of the ID magnetic center. Such misalignments can result in photon flux losses, spectral shifts toward lower energies, and broadening of the resonance. This work presents the application of O. Chubar’s* spectrum-based alignment method to one of the new SIRIUS IVUs, aiming to optimize its performance at the beamline.

Speaker: Gabriel Ascenção (Brazilian Synchrotron Light Laboratory)

16:00 SPS-II beam injection using a non-linear kicker

SPS-II is the fourth generation electron storage ring in
Thailand. The medium-sized ring constructed with a Double-
Triple Bend Achromat (DTBA) cell provides low emittance
and high capacity for the beamlines. To complement the
compact storage ring with DTBA cell, a Non-Linear Kicker
(NLK) was chosen for beam injection. This approach not
only simplifies the injection system by reducing the number
of required kickers but also enhances the overall reliability
and efficiency of the injection process. This paper
discusses the injection dynamics and optimization strategies
associated with implementing the NLK in the SPS-II storage
ring. Through comprehensive simulations and analyses, we
demonstrate the NLK’s efficacy in achieving high injection
efficiency.

Speaker: Thapakron Pulampong (Synchrotron Light Research Institute)

16:00 Stable generation of high-quality beam by 3-GeV low-emittance linear accelerator in NanoTerasu

The construction of a low-emittance 3-GeV linear accelerator as an injector system of a new high-brilliance synchrotron radiation facility “NanoTerasu” was completed in January 2023. After beam commissioning of the accelerator complex for several months, the synchrotron radiation for user experiment was provided in April 2024 as planned []. The 3-GeV compact linear accelerator consists of 40-MeV injector system and C-band accelerator. The electron beam with a bunch charge of more than 0.5 nC and normalized emittance of less than 2 mm mrad is generated from an electron RF gun system with a gridded thermionic cathode at a “transparent” grid condition [*]. In the 40-MeV injector system, the bunched beam with a bunch length of 5 ps and normalized emittance of less than 10 mm mrad is generated. In usual operation, the bunched beam is accelerated up to 3 GeV and injected stably into the storage ring. In this presentation, we report on the establishment of beam adjustment by tuning RF amplitude and phase. We also report on the beam performance obtained, including beam stability, and comparing the design beam envelope and measured beam optics in the linear accelerator.

Speaker: Dr Koichi Kan (National Institutes for Quantum Science and Technology)

16:00 Status of S-PRESSO, A superconducting undulator for the European XFEL

Up to six superconducting undulator modules are foreseen to be installed downstream with respect to the permanent magnet undulators of SASE2, one of the two hard X-ray lines at European XFEL. Aim is to provide users with photon energies above 30 keV. The superconducting undulator pre-series module (S-PRESSO) is currently under production.Before installation in the tunnel, the magnetic structures are characterized in the vertical He bath cryostat SUNDAE1 (Superconducting UNDulAtor Experiment), and in the horizontal test stand to perform quality assurance of the SCU coils installed in the final cryostat SUNDAE2. This contribution describes the status of the project.

Speaker: Sara Casalbuoni (European X-Ray Free-Electron Laser)

16:00 Study of electron density in capillary discharge plasma for laser plasma accelerator

Laser-plasma accelerators have demonstrated the ability to accelerate high-energy electrons but require improved beam stability and repeatability for practical applications. Pre-formed plasma channels enhance the stability in Laser-Wakefield Accelerators by maintaining laser focus over longer distances, increasing energy transfer efficiency. The characteristics of such channels are highly dependent on capillary geometry, gas parameters, discharge setup, and repetition rate. This study investigates the electron density profiles in plasma from gas-filled capillary discharges. Using interferometry and Stark broadening, we measured profiles under varying conditions, achieving densities of (2-6)×10^18 cm^-3. In this presentation, we showcase the stability and uniformity of the plasma, highlighting its capability to preserve beam quality in high-energy, high-repetition-rate applications. This type of plasma source is a crucial technology for the plasma accelerator-based Free Electron Laser developed at ELI-ERIC as well as for the EuPRAXIA project. Also, we discuss the conceptual design of plasma diagnostics for providing 'real-time' information in high-repetition-rate applications.

Speaker: Alex Whitehead (Extreme Light Infrastructure Beamlines)

16:00 Study of the microbunching instability in the THz FEL at PITZ

The PITZ accelerator comprises a radiofrequency photogun and an RF booster cavity, capable of generating electron beams with bunch charges of several nC and momenta of up to ~24 MeV/c. To achieve higher beam currents which is a key parameter for the single-pass high-gain THz FEL, a four-dipole chicane is installed upstream of the undulator. Given the low beam energy and high bunch charge, amplification of microbunching instability (MBI) could be expected in the photo injector. Since the modulation induced by MBI typically occurs in the micrometer wavelength range—comparable to the THz wavelength—the impact of MBI on the THz source at PITZ will be analyzed and discussed in this paper.

Speaker: Biaobin Li (Deutsches Elektronen-Synchrotron DESY)

16:00 Study on deposition method for improving quantum efficiency and lifetime of NEA-GaAs photocathode using cesium, antimony and oxygen

Negative Electron Affinity (NEA) activated GaAs photocathodes are the only one capable of generating spin-polarized electron beam larger than 90%. However, the NEA layer currently made from mainstream cesium (Cs) and oxygen (O) is chemically unstable, the NEA-GaAs photocathode has a rapid quantum efficiency degradation over time or electron beam. As a result, it requires an operating vacuum pressure of below 10-9 Pa and has a short lifetime. Recently, a new NEA layer using heterojunctions with semiconductor thin films of alkali metals and antimony (Sb) or tellurium has been proposed. Recent works have shown that the deposition of the NEA layer was realized using cesium, antimony and oxygen. In this work, we attempted to introduce Sb at two different timing. One is introduction from the beginning, and the other one is introduction after Cs and oxygen deposition. We systematically investigate the deposition temperature and antimony thickness to find the optimal conditions for improving quantum efficiency and lifetime. We will report the latest results.

16:00 Study on radiation performance of circular polarization in traditional APPLE-KNOT undulator

The traditional APPLE-KNOT undulator forms composite magnetic fields by superimposing APPLE fields and KNOT fields with the period ratio of 2:3. The APPLE field serves as the main component to approximate the target photon energy, while the KNOT field acts as an additional component to transversely deflect the electron beam away from axis. Variable polarization states can be generated with a low on-axis heat-load in the APLLE-KNOT undulator. Compared the traditional APPLE-KNOT undulator with the APPLE II undulator, a sharp reduction on flux of circular polarization state can be observed. In this paper, this phenomenon is detailed discussed from the theoretical perspective. It indicates that a larger period length of KNOT field than APPLE field with a strong field contribution of KNOT field will greatly suppress the flux of circular polarization state, which is highly consistent with the simulation result. To keep a good performance both at the linear and circular polarization states with little on-axis heat load, the period ratio and field amplitude ratio between APPLE and KNOT fields should be comprehensively optimized.

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

16:00 Studying photoemissive properties of stable Cs-Sb compound thin-film photocathodes using a combination of Monte Carlo simulations and Density Functional Theory

Cs-Sb compound thin-film photocathodes are an excellent candidate to produce bright electron beams for use in various accelerator applications. Despite the virtues of these photocathodes being known, the mechanics that govern their photoemission are not well-understood. Crystalline and other material properties affect the mean transverse energy (MTE) and quantum efficiency (QE) and, thus, the overall brightness. Electrons photoemitted from these thin-film crystals experience an unexpected energy loss similar to that found in bulk crystals despite their being a significantly shorter transport phase. Deeply understanding the relationship between the crystalline properties and the emitted electron beam’s brightness, as well as this drop in energy, is vital to generating ultra-bright electron beams for advanced accelerator applications. The purpose of this work is to use the Monte Carlo method to simulate photoemission from semiconducting films with electronic band structure parameters supplied by Density Functional Theory (DFT) calculations. This method is used to study all steps of photoemission and to identify the key parameters necessary for optimizing photocathode performance.

Speaker: Daniel Franklin (Northern Illinois University)

16:00 Surface cleaning and chemical process analysis of high quantum efficiency magnesium photocathode

Magnesium (Mg) has been demonstrated to be a safe, stable, and reliable photocathode for both normal-conducting and superconducting RF guns.
Pure magnesium, with its low work function of 3.6 eV, exhibits significant quantum efficiency (QE) improvement — by up to two orders of magnitude — following appropriate surface cleaning procedures. This study investigates the chemical processes occurring on the material's surface in its as-received state and after thermal and plasma cleaning. These findings provide critical insights into the mechanisms underlying QE enhancement on this metallic photocathode.

Speaker: Rong Xiang (Helmholtz-Zentrum Dresden-Rossendorf)

16:00 The APS linac refurbishment program at Argonne

The linac refurbishment program is an initiative to modernize the linear accelerator (linac) at the Advanced Photon Source (APS) for the APS Upgrade (APS-U). This program addresses critical operational challenges, including obsolete components and the need for higher beam energies. Key projects involve upgrading RF stations to 50 MW capacity using modern klystrons , solid-state modulators, and digital low level rf controls, enabling the linac to achieve higher energy. New thermionic RF guns are being developed and installed to replace aging guns, enhancing beam stability and reliability. Magnet power supplies are being overhauled with modern units that offer faster response times and improved control, and the timing system is being upgraded for better precision and flexibility. Collectively, these efforts ensure that the linac will meet the stringent performance and reliability requirements of the APS-U, supporting advanced scientific research with improved operational stability.

Speaker: Yine Sun (Argonne National Laboratory)

16:00 The Australian X-Band electron test accelerator

The University of Melbourne's Xband Laboratory for Accelerators and Beams (XLAB) is collaborating with CERN on the design and testing of high-gradient accelerating structures. Together with the Australian Synchrotron (ANSTO), we are developing the X-Band Electron Test Accelerator (xBeta), a compact high-gradient electron accelerator.
The system will feature a photogun to generate short electron bunches of less than 10ps, producing pulsed electron beams of energy 5–30 MeV at repetition rates of 50–400 Hz. A spectrometer will be available for precise characterization of the energy spectrum and the facility will be used to explore medical and industrial applications of high-gradient accelerator technology.
Applications include electron bombardment to create nitrogen-vacancy centres in diamond, mono-energetic X-rays for medical imaging offering enhanced contrast and reduced radiation doses and novel channels for medical isotope production. These features make the system a versatile platform for innovations in fundamental research, healthcare, and industry.

Speaker: Roger Rassool (The University of Melbourne)

16:00 The future of the CLEAR facility: consolidation, ongoing upgrades and its evolution towards future electron facilities at CERN

The CERN Linear Accelerator for Research (CLEAR) is a versatile 200 MeV electron linac followed by an experimental beam-line, operated at CERN as a user facility. Its user community includes research groups working on beam instrumentation R&D, advanced acceleration techniques and irradiation studies, including medical applications. A recent internal review has confirmed the excellence of its scientific output and its strategic interest for the laboratory, extending the facility operation until at least 2030. In this paper we discuss the consolidation actions needed for continued operation together with the ongoing hardware improvements and their impact on the future experimental program. These upgrades include a new front-end for the laser system allowing for a highly flexible time structure, better stability and higher repetition rates, plus the implementation of a second beam line whose optics has been designed to match user requirements and will provide additional testing capability. Finally, we discuss the potential role of CLEAR in the path towards future high-energy electron facilities at CERN.

Speaker: Antonio Gilardi (University of Naples Federico II)

16:00 Towards lossless beam transmission in the first LHe-free Nb₃Sn SRF e-linac

Superconducting radio-frequency (SRF) electron linear accelerators (e-linacs) provide significant advantages over conventional room-temperature accelerators, especially in their capacity to accelerate high-intensity continuous-wave (CW) beams. Recently, the first liquid helium-free (LHe-free) Nb₃Sn SRF cavity was successfully operated at the Institute of Modern Physics of the Chinese Academy of Sciences (IMP, CAS), achieving 5 MeV, 200 mA CW beam acceleration and demonstrating the feasibility of miniaturized SRF e-linacs. However, the lack of time structure in the injected beam and its velocity mismatch with the cavity's optimal beta value lead to approximately 50% beam loss within the SRF cavity, presenting a critical challenge for long-term operation. This paper presents an upgrade design of the existing e-linac, ensuring 100% transmission in the SRF cavity while maintaining a compact configuration. Detailed beam dynamics design and multi-particle simulation results are discussed.

Speaker: Yimeng Chu (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Twin-bunch modelling in linear accelerators for plasma wakefield acceleration

Twin electron bunches accelerated by high-energy linacs are attracting increasing interest especially in twin free-electron laser (FEL) pulse generation and beam-driven plasma wakefield acceleration (PWFA) studies. High-energy linacs may benefit from plasma accelerators, where a trailing bunch is accelerated in GV/m fields in a plasma wave driven by the leading bunch. This could facilitate high-energy physics, as well as greatly increase the available photon energy range of existing FELs without increasing the footprint. Here, initial analytical studies of twin-bunch generation in FLASH accelerator are carried out. With the initial beam longitudinal phase space properly tuned by temporally shaping the photocathode laser, together with optimizing linac settings, high-quality twin electron bunches with tunable delay and simultaneous bunch shaping can be generated, which is essential for energy-efficient PWFA with low energy spread.

Speaker: Tianyun Long (Deutsches Elektronen-Synchrotron DESY)

16:00 Two in-vacuum undulators developed for the Sirius

The Shanghai Synchrotron Radiation Facility (SSRF) project team developed two in-vacuum undulators (IVUs) with a period length of 18.5 mm and a gap of 4 mm for the SIRIUS. This paper introduces the design and magnetic field measurements. The results indicate that with a gap range of 4-20 mm, the phase error is less than 3°, the quadrupole field is less than 37 Gs, the sextupole field is less than 83 Gs/cm, and the octupole field is less than 84 Gs/cm².

Speakers: Cheng Yu (Shanghai Advanced Research Institute), Shudong Zhou (Shanghai Advanced Research Institute)

16:00 Universal mode of operation of the APPLE II undulators at the MAX IV 1.5 GeV ring

At the MAX IV 1.5 GeV ring, two APPLE II undulators with period lengths of 84 mm (Bloch) and 95.2 mm (FinEstBeams) cover minimum photon energies of 7 eV and 4 eV, respectively. Operating below 80 eV, the polarization state is distorted significantly by the beamlines' optical elements. A combination of helical and linear inclined modes during undulator operation - the so-called universal mode - can compensate for the distortions. In this paper, we describe how we compensate for the effect of the undulators on the beam orbits and ring optics when operating in universal mode. Additionally, some of the achieved commissioning results at both beamlines will be shown.

Speaker: Michael Holz (MAX IV Laboratory)

17:40 Improvement of NSRRC superradiant THz FEL

National Synchrotron Radiation Research Center (NSRRC) has been advancing its capabilities in producing intense terahertz (THz) radiation from a superradiant free-electron laser (FEL). This system utilizes a photoinjector operating in its velocity bunching mode to achieve ultra-short electron bunches. However, the highest THz frequency from the facility is determined by the shortest achievable bunch duration. Currently, the highest THz frequency is limited to 1.4 THz, corresponding to the shortest attainable bunch duration of 240 fsec from the photoinjector. To enable higher THz frequency operation, the NSRRC team is investigating the implementation of a dogleg beamline for enhanced bunch compression. We studied the possibility to generate a 25 MeV electron beam compressed to a 100 fsec bunch duration. Using the PUFFIN code, we have calculated the superradiant THz undulator radiation achievable with these compressed bunches. The results demonstrate the potential to produce intense 3 THz radiation, marking a substantial enhancement in the frequency range and intensity of the THz FEL output.

Speaker: Shan-You Teng (National Central Univeristy)

16:00 → 18:00 Tuesday Poster Session: TUPS

16:00 3D characterization of plasma density in capillary discharges for plasma-based accelerators

Accurate characterization of plasma density profiles is vital for optimizing plasma-based accelerators, as density directly affects beam acceleration and quality. Plasma capillaries also serve as lenses and for beam guiding, highlighting their role in advanced accelerators. This study measures longitudinal and transverse density profiles of plasma capillaries, achieving 3D characterization using Stark broadening techniques.
Two optical lines capture emitted plasma light. Parameters include gas flow rate, operating mode (pulsed/continuous), voltage, capillary type and geometry, gas type, and repetition rate, allowing evaluation of operational impacts on plasma density.
Results show consistent density measurements across various positions, indicating the method's capability to capture spatial variations in plasma density.
Understanding these profiles is crucial for developing and optimizing laser-driven and beam-driven plasma accelerators, as well as enhancing plasma lenses and beam guiding, enabling fine-tuning of parameters to maximize acceleration efficiency and control beam quality.

Speaker: Romain Demitra (Istituto Nazionale di Fisica Nucleare)

16:00 A standalone radio frequency quadrupole accelerator for swift heavy ions

The radio frequency quadrupole (RFQ) is known for bunching, focusing and acceleration of ion beam and more importantly, it does not require transverse focusing element like quadrupole magnets between accelerating cells compared to drift tube linacs. By pushing the limits of handling surface electric field between RFQ vanes, it is possible to make a standalone 352 MHz RFQ reaching 1.8 MeV/u energy gain for swift heavy ions upto mass to charge ratio (A/q) ≤ 4. Special RFQ vane material of cryo Cu is considered by which surface electric fields can be pushed around 50 MV/m* and the whole RFQ is designed within a length of 5m which is substantially less than any RFQ + DTL combination of equivalent energy gain accelerator for heavy ions. Such systems are highly promising for compact medical LINACS and as well as standalone facilities for nuclear physics experiments. The adiabatic bunching and focusing inherently stabilize the beam dynamics at proper RFQ power and cavity tuning. We present the beam optics design using PARMTEQ code and RFQ cavity design along with thermal analysis using CST MWS. The error analysis is provided to support the design in terms of practical feasibility.

Speaker: Sarvesh Kumar (Inter-University Accelerator Centre)

16:00 ABEL: The adaptable beginning-to-end linac simulation framework

We introduce ABEL, the Adaptable Beginning-to-End Linac simulation framework developed for agile design studies of plasma-based accelerators and colliders. ABEL’s modular architecture allows users to simulate particle acceleration across various beamline components*. The framework supports specialised codes such as HiPACE++, Wake-T, ELEGANT, GUINEA-PIG and CLICopti, which facilitate precise modelling of complex machine components. Key features include simplified models for addressing transverse instabilities, radiation reactions, and ion motion, alongside comprehensive diagnostics and optimisation capabilities. Our simulation studies focus on the HALHF plasma linac, examining tolerances for drive beam jitter, including effects of self-correction mechanisms. Simulation results demonstrate ABEL's ability to model emittance growth under transverse instability and ion motion, highlighting the framework’s adaptability in balancing simulation fidelity with computational efficiency. The findings point towards ABEL’s potential for advancing compact accelerator designs and contribute to the broader goals of enhancing control and precision in plasma-based acceleration.

Speaker: Jian Bin Ben Chen (University of Oslo)

16:00 Accelerating wakefield that reduces the energy spread of the witness due to beam loading

Acceleration by the wakefield in the plasma can provide compact sources of relativistic electron bunches of high brightness. Free electron lasers and particle colliders, for using plasma wakefield accelerators, require high efficiency and bunches with low energy spread. The best way to achieve low energy spread is using profiled bunches which form plateau on the wakefield. However, in experimental setups it is easier to use gaussian-kind bunches. Our numerical investigations show that thus form of bunches can assure plateau on the central part of the bunch, higher accelerating field on the tail of the bunch and lower accelerating field on its head. This field distribution leads to decreasing of the energy spread of bunches.

Speaker: Ilia Demydenko (V. N. Karazin Kharkiv National University)

16:00 Achievement of LIU longitudinal parameters at the CERN SPS

To prepare the Super Proton Synchrotron (SPS) as an injector for the High Luminosity Large Hadron Collider (HL-LHC), its Radiofrequency (RF) system was majorly upgraded. The 200 MHz travelling wave structures were rearranged, adding two solid-state power amplifiers and a new Low-Level RF (LLRF) system. The increase in RF power and reduction of the beam coupling impedance at the fundamental frequency were designed for capture and acceleration of four trains of 72 bunches spaced by 25 ns at an intensity of 2.3e11 protons per bunch with bunch lengths of 1.65 ns ±10% at SPS extraction. These beam parameters have first been demonstrated in 2024 after careful optimisation of all the main longitudinal settings: voltage program at fundamental and higher harmonics, interplay of one turn-delay feedback, feedforward and longitudinal damper, as well as controlled emittance blow-up. This contribution details the achieved beam parameters and the conditions that allowed them, along with the encountered limitations.

Speaker: Giulia Papotti (European Organization for Nuclear Research)

16:00 Activation of GaAs with a Cs-Te thin film

GaAs cathodes with thin-film Negative Electron Affinity (NEA) surfaces affixed have been used to generate spin-polarized electron beams for decades, but still suffer from short lifetimes. Heterojunction NEA surfaces have shown promise in improving cathode lifetimes, but further optimization of cathode activation and surface deposition is possible. Here we report the results of cathode activation with evaporative deposition of a CsTe surface performed at Hiroshima University.

Speaker: Zachary Liptak (Hiroshima University)

16:00 Advanced growth and characterization of alkali antimonide photocathodes for bright beam applications

The properties of the photoemitting electron sources are the determining factors contributing to the performance of the most advanced electron accelerator applications such as particle colliders, X-ray free electron lasers, ultra-fast electron diffraction and microscopy experiments. Therefore, low mean transverse energy (MTE), high quantum efficiency (QE) along with long operational lifetime and robustness under high electric fields and laser fluences must be demonstrated by the photocathode for these bright beam applications. Recent investigations have revealed that the epitaxial growth of single-crystal cesium antimonides can be achieved by photocathode growth on lattice-matched substrates. In this paper, the experimental setup for highly promising alkali antimonide photocathode growth by molecular beam epitaxy on lattice-matched substrates and in-situ characterization with reflection high-energy electron diffraction (RHEED) has been presented. To adapt the L-band RF gun of Argonne Cathode Test-stand (ACT) for extensive testing of alkali antimonides in real accelerator conditions, compatible cathode plug design, and smooth transportation process have been developed and described.

Speaker: Tariqul Hasan (Northern Illinois University)

16:00 Advancing plasma accelerator science: Insights from the EuPRAXIA Doctoral Network

The EuPRAXIA Doctoral Network (EuPRAXIA-DN) trains the next generation of scientists in plasma-based accelerator technologies, addressing challenges in laser-plasma interactions, advanced beam diagnostics, and novel applications.

This contribution highlights progress made in three critical areas: ) real‑time characterization of capillary discharge plasmas to stabilize laser‑wakefield accelera-tion, (ii) femtosecond‑precision X‑band low‑level RF (LLRF) control for the compact EuPRAX-IA@SPARC_LAB injector, and (iii) active‑plasma‑lens (APL)–based beam transport enabling extreme‑ultraviolet free‑electron‑laser (EUV‑FEL) operation within four me-ters of undulator. The innovative training elements with-in the network, such as the EuPRAXIA School on Plasma Accelerators held in Rome in April 2024 and upcoming EuPRAXIA Camps, are also discussed. It is shown how these foster knowledge exchange and skill development for the network's Fellows and the wider plasma accelera-tor community.

Speaker: Prof. Carsten Welsch (University of Liverpool)

16:00 An overview of research on nanostructured negative electron affinity GaAs photocathode at Jefferson Lab

Inspired by the progress of surface plasmon research and the rapid development of nanotechnology, we embarked on an endeavor aiming to improve the GaAs-based photocathode performance by patterning semiconductor wafer surfaces with pillar arrays on the scale of hundreds of nanometers. Over the past a few years, extensive research effort involving both simulation and experimental studies have been made, leading to the demonstration of some important underlying physical mechanisms such as Mie-resonance at different laser wavelengths and strong quantum efficiency enhancement over their peers with conventional flat surfaces. In this report, we present an overview of our research activities including previous work, current status, and the near future plan about an on-going effort to test newly designed nanostructured photocathodes in a high voltage electron gun.

Speaker: Shukui Zhang (Thomas Jefferson National Accelerator Facility)

16:00 Analysis of energy spread and longitudinal field characteristics in flat beam PWFA

The plasma wakefield excited by highly asymmetric drivers has recently been the subject of extensive study. Unlike the case of axisymmetric drivers, the transverse focusing and longitudinal fields exhibit coordinate dependencies. There are still open questions regarding the longitudinal characterization of this blowout regime. In this work, we analyze the transverse dependence of the longitudinal field and explore the transverse distribution of the energy spread in witness beams for drivers with varying asymmetric emittances. These analytical results are compared with Particle-in-Cell (PIC) simulations to provide deeper insights into the dynamics of asymmetric wakefield interactions.

Speaker: Pratik Manwani (University of California, Los Angeles)

16:00 Assembly and testing of a QWR for the new ISIS MEBT

The quarter wave resonator (QWR, a.k.a. λ/4 resonator) for the new ISIS MEBT is a bunching cavity that longitudinally compresses the H- beam into smaller bunches. It has two gaps with a distance of βλ/2 between mid-gaps, and works in π mode at the resonant frequency of 202.5 MHz, with a phase angle of -90 degrees, and a maximum voltage per gap (E0L) of 55 kV. The detailed RF and thermal design was developed, followed by the manufacturing of a prototype, all being presented elsewhere. Several mechanical issues were noticed with the RF finger strips and tuners during the assembly of the prototype cavity. The manual tuner (to account for the manufacturing tolerances and the vacuum load) was machined to the final dimension to achieve the desired resonant frequency, according to the Vector Network Analyser (VNA) measurements. The measured quality factor was found to be much lower than expected, which required a redesign of some of the RF seals. The cavity was powered and conditioned in a relatively short time up to a nominal power, but severe multipacting was observed, initially only at low power, but later also at medium power levels, which required a creative approach to be fixed without a major cavity redesign.

Speaker: Dr Iker Rodriguez (Science and Technology Facilities Council)

16:00 Assembly of the IFMIF SRF Linac cryomodule

Complementing its contributions to the JT-60SA and ITER fusion reactors, Fusion for Energy contributes to the R&D for material characterization facilities. Under the Broader Approach agreement, Europe and Japan are developing the Linear IFMIF Prototype Accelerator (LIPAc) in Japan, a deuteron accelerator demonstrator producing neutrons by nuclear stripping reactions on a liquid lithium target, part of the International Fusion Materials Irradiation Facility (IFMIF) project.
In 2024, LIPAC prepared for the installation of the SRF cryomodule, concluding its construction. As first prototype, the cryomodule assembly faced challenges at various stages. Started in March 2019, the assembly was paused during its cleanroom phase due to quality issues with the superconducting solenoids, resuming in Aug. 2022. Further issues delayed the completion of the cleanroom activities until Sept. 2024.
In 2024, the cryomodule assembly progressed at a good rate. The clean room worked concluded in Sept. and by late 2024 the cold mass was ready for insertion into the vacuum vessel, with transfer to the vault planned for early 2025.
In this paper, we will outline the critical steps of this assembly process.

Speaker: Janic Chambrillon (Fusion for Energy)

16:00 Avoiding overcooled ion beams by exciting energy spread through electron cooling

Ion accelerators use electron cooling to improve luminosity and beam lifetime. However, extremely low momentum spread in a cold beam weakens Landau damping, enabling the development of instabilities and potentially decreasing lifetime. To combat this, the NICA Booster electron cooling system allows to generate electron beams with oscillating energy to increase the momentum spread in ion beams. Here we describe the implementation of the energy oscillation technique and provide numerical calculations predicting the achievable momentum spread.

Speaker: Mr Eldar Urazov (Budker Institute of Nuclear Physics, Novosibirsk State University)

16:00 Beam dynamics optimization in high-brightness Photo Injector with various photocathode laser pulse shapes

At PITZ, a comprehensive study is conducted to analyze the factors influencing emittance growth in the European XFEL (EuXFEL) continuous wave (CW) setup. Emittance growth due to space charge effects can be mitigated using advanced photocathode laser pulse shapes. To optimize beam quality, multiobjective optimization studies using ASTRA are performed, focusing not only on minimizing emittance but also on maximizing beam brightness for various laser temporal profiles and dura-tions. The optimization is initially carried out for the CW injector section planned for EuXFEL. The optimized cases are then further tracked through start-to-end (S2E) simulations to evaluate their behavior in the compression stages of EuXFEL. A comparative analysis of gaussian, flattop, ellipsoidal, and inverted parabolic laser profiles is presented, assessing their efficiency not only in terms of emittance but also in 4D and 6D brightness. Finally, the results of the optimized photoinjector setup and the beam properties after the final bunch compression will be presented.

Speaker: Sumaira Zeeshan (Deutsches Elektronen-Synchrotron DESY)

16:00 Beam transport and diagnostics study for a space plasma experiment at MITHRA

The MITHRA facility being commissioned at UCLA, will be capable of producing low emittance beams with 100s pC of charge with bunch lengths in the 100s of fs range having an energy of 60 MeV. This can be used to drive plasma wakefields and the long bunch length compared to the plasma skin depth allows us to create a beam with a broadband energy spectrum. The energy spectrum resembles the electron spectrum observed in the radiation belts of Jupiter and can be used as a proxy for electron radiation exposure for flyby operations. In this paper, we discuss the beam transport, plasma source and diagnostics needed for the proposed experiment.

Speaker: Pratik Manwani (University of California, Los Angeles)

16:00 Beamline to inject laser plasma accelerated electrons to a quasi-isochronous compact storage ring

Laser plasma accelerators (LPAs) can produce high-energy electron bunches from short distances. Successfully coupling these sources with dedicated compact storage rings tuned to quasi-isochronous conditions would demonstrate the capture and storage of ultra-short electron bunches in a circular accelerator. Electron bunches generated from LPAs can have a correlated distribution in longitudinal phase space: a chirp, as well as comparably large angular divergence and energy spread. We, therefore, design a flexible beamline that can transport ultrashort bunches with large angular and energy spread to a ring. We have used the accelerator design programs OPA and MAD8 to build up optical model of a beamline. The line is composed of focusing and dispersion matching sections. A set of small angle bending magnets counteracts the dispersion created by injection septum of the storage ring and provides quasi-isochronous bunch transfer with a flexible value of longitudinal dispersion (R56).

Speaker: Jens Schaefer (Karlsruhe Institute of Technology)

16:00 Characterization of the energy spectrum of a 30-MeV cyclotron-based quasi-monoenergetic neutron beam using a time-of-flight spectrometer

We conducted time-of-flight (TOF) measurements to characterize the spectrum of a quasi-monoenergetic neutron beam driven by a 30-MeV proton cyclotron at the National Atomic Research Institute in Taiwan*. Neutrons were produced by irradiating 30-MeV protons onto a 1-mm-thick beryllium target. The developed TOF spectrometer comprised two 2-inch EJ-309 organic scintillators positioned 200 mm from the neutron beam port to detect gamma rays emitted from the target, and a 3-inch EJ-309 scintillator placed at a flight distance of 2940 mm to measure neutrons. As the signals of gamma-ray bursts triggered TOF measurements at an RF frequency of 73.13 MHz, repetitive distributions of coincidence events between gamma-ray and neutron-related signals were observed, resulting in an effective time window of 13.67 ns for measuring neutrons in the energy range of 16.19–30 MeV. The measured neutron spectrum exhibited a peak at 26 MeV, verifying the simulated spectrum obtained from an MCNP Monte Carlo model. Additionally, we developed a fast-timing scintillator module that measured the proton bunch duration as 0.97 ns, enabling accurate estimation of the energy resolution of the neutron spectrum.

Speaker: Tzu-Hsiang Lin (National Tsing Hua University)

16:00 Compact CW 1-15 MeV 10-100 kW electron accelerators

Our understanding underscores a global demand for affordable, efficient, and compact/mobile electron beam solutions across various sectors, including:1.Replacement of Co60 sources: Co60 radiation sources must be replaced with safer and more efficient alternatives. 2.Isotope production and medical accelerator treatment: Accelerators utilized in isotope production and medical treatments necessitate reliable and cost-effective solutions.3.Medical sterilization via electron beams: Utilizing electron beams for medical sterilization purposes, ensuring safety and efficacy in healthcare settings. 4. Employing electron beams for food processing applications, enhancing food safety and preservation. 5/Electron beam for water processing: Electron beams are utilized for water treatment and purification, addressing water quality concerns.
The proposed solution employs a 1497 MHz frequency, enabling compactness and efficiency. The accelerator design utilizes a single linac and racetrack configuration, ensuring gradual acceleration while minimizing footprint. Future directions include integrating NB3Si-based superconducting cavities with cryocoolers for higher beam energies and scalability.

Speaker: Milorad Popovic (Muons (United States))

16:00 Comprehensive studies of linear accelerators for muons in the medium velocity range

The muon linac has been developed at J-PARC to accelerate muons from thermal energy (25 meV) to 212 MeV using electrostatic extraction and four different types of radio-frequency cavities: RFQ, IH-DTL, DAW-CCL, and disk-loaded structures.
Although some of the technologies employed were relatively novel, most proof-of-principle demonstrations have been successfully completed through prototype testing and actual production.
Based on these experiences, it has become possible to propose a shorter or more efficient schematic design derived from the current design.
In this poster, the new schematic design will be presented.

Speaker: Masashi Otani (High Energy Accelerator Research Organization)

16:00 Compressed ultrashort pulse injector demonstrator

High brightness electron beams have a wide range of applications ranging from accelerator-based light sources to ultrafast electron diffraction and microscopy. High accelerating gradient photoinjector is an important tool to generate brighter electron beams. However, high gradient photoinjector suffers issues from material breakdown due to extremely high surface electric fields. One possible path to simultaneously achieve high gradient and suppress breakdowns is to reduce the rf pulse duration fed into the photoinjector. Such an approach was recently demonstrated at the Argonne Wakefield Accelerator (AWA) facility where they commissioned an X-band photoinjector at 400 MV/m cathode field without significant breakdown rates. SLAC National Accelerator Laboratory recently developed rf pulse
compression technology optimized for short pulses up to 500MW. We propose to develop an X-band photoinjector which can utilize these ultrashort rf pulses to produce surface fields at 500 MV/m or higher at the cathode. This presentation focuses on the design of the X-band photoinjector.

Speaker: Ankur Dhar (SLAC National Accelerator Laboratory)

16:00 Concrete structure and shielding in the IFMIF-DONES main building

IFMIF-DONES is devoted to the irradiation of fusion materials, based on a high energy linear accelerator and a lithium-deuteron stripping reaction, creating the high intensity neutron source which simulates the damage on the 1st wall of the future fusion reactors.
The core of the facility are the Accelerator, Lithium and Test Systems hosted inside IFMIF-DONES Facility, in the so-called Main Building (MB). The detailed design of this building was initiated first during the IFMIF-EVEDA activities in the framework of the Broader Approach (EU-Japan Bilateral Agreement) and pursued within EUROfusion for the development of an Early Neutron Source (WPENS). The design has evolved in which the main areas in terms of neutronics shielding are the Accelerator Vault and the Test Cell, where the nuclear reaction takes place and the materials are irradiated.
Additional rooms like the Access Cell or the radwaste treatment area, are key in terms of shielding.
In this work, it is presented the status of the integration into the design of the MB structure of the safety requirements from the definition of the radiation maps, neutronics studies and heavy concrete vs ordinary concrete capabilities.

Speaker: Maria Luque (Consorcio IFMIF-DONES España)

16:00 Current status of beam commissioning at the Frankfurt Neutron Source

The Frankfurt Neutron Source FRANZ will be a compact accelerator driven neutron source utilizing the 7Li(p,n)7Be reaction with a 2 MeV proton beam. The 700 keV RFQ has been sucessfully commissioned with a 10 mA proton beam. Conditioning of the subsequent IH-type cavity has been performed up to 10 kW. We also report on RFQ emittance measurements performed with a slit grid emittance device. In addition, a fast faraday cup (FFC) was used for bunch shape measurements behind the RFQ.

Speaker: Dr Hendrik Hähnel (Goethe University Frankfurt)

16:00 Current status of the MYRRHA project at IAP Frankfurt

As part of the MYRRHA project, which is being implemented in Mol, Belgium, two of the planned 17 normal-conducting CH cavities have been built and tested at several kilowatts of RF power. Since the cooling concept for the stems was revised after their construction, concerns arose that the two existing cavities might have suffered a degradation in performance during high-power testing due to the outdated cooling system. Consequently, it was decided to subject cavity CH02 to renewed LLRF measurements at IAP Frankfurt to ensure that its performance has not deteriorated. The cavity is then scheduled for high-power testing at the newly established high-power station at IAP. This will not only serve to commission the test stand but also recondition the cavity

This paper summarizes the recent LLRF measurements performed on CH02 and reports on the current status of preparations for the upcoming conditioning.

Speaker: Klaus Kümpel (Goethe University Frankfurt)

16:00 Design and EM simulations of 750 MHz IH-DTL tank for carbon ion in medical applications

This paper presents the design of 750 MHz IH-DTL (Interdigital H-mode Drift Tube Linac) tank, specifically developed to be part of a carbon ion injector for medical treatment applications. These sections provide a highly efficient solution for ion acceleration in the 5 to 10 MeV per nucleon energy range, offering a high shunt impedance. The study includes simulations of electromagnetic fields using CST Software, and beam dynamics simulations through a KONUS-type configuration

Speaker: Gabriela Moreno (Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas)

16:00 Design and simulation of negative hydrogen ion extraction system for the C30 cyclotron accelerator

This study focuses on the design and simulation of a negative hydrogen ion beam extraction system for the C30 cyclotron accelerator. The filament-driven arc discharge multi-cusp ion source, capable of producing H⁻ ions with 30 keV energy and 2 mA current. The ion source consists of two main components: the driver and the extraction system, with the latter playing a crucial role in ensuring the quality and efficiency of the generated ion beam.
The C30 cyclotron capable of accelerating protons to 30 MeV and deuterons to 16 MeV. It is utilized in medical, industrial, and research applications, particularly in the production of isotopes.
The extraction system design was carried out using the three-dimensional ion-optics simulation code IBSimu. It includes three electrodes: the plasma electrode, the puller, and the ground electrode. The puller is equipped with a water-cooling system and four permanent magnets to create a magnetic field profile for the suppression of co-extracted electrons. The optimized design of the extraction system not only minimizes beam emittance growth but also enhances the overall performance of the accelerator.

Speaker: Keyvan Tabaei (University of Isfahan)

16:00 Design guidelines and longitudinal dynamics for plasma-based, extreme compression

High-brightness, ultra-high peak current electron beams are of significant interest to applications including high-energy colliders, strong field quantum electrodynamics, and laboratory astrophysics. Despite such interest, compressing tightly-focused electron beams to attosecond pulse durations and mega-amp peak currents while preserving beam quality remains a challenge. In this work, we examine the feasibility and challenges involved in generating such extreme beams using plasma-based compression. Using simulations, we demonstrate that the large electric field gradients in plasma wakefields enable orders of magnitude higher compression than conventional radiofrequency compressors. Scalings of various beam properties with respect to accelerator and plasma parameters are explored with limitations on achievable final beam brightness evaluated. Optimal beam and plasma conditions are investigated for different applications, with the goal of experimentally demonstrating this technique at the FACET-II facility at SLAC National Accelerator Laboratory. Insights gained from this study will help design the next-generation of high-brightness beams for new frontiers in scientific research.

Speaker: Claudio Emma (SLAC National Accelerator Laboratory)

16:00 Design iteration of a compact photoinjector

The study of high-brightness, low-emission photocathode injectors and high-gradient electron guns is an important topic in the field of linear accelerator. Research has been carried out on cryogenic photocathode electron guns to obtain higher quality beams with shorter driven laser. However, problems such as multipole fields and dark currents have been found in the research experiments. An iterative design was carried out to address these issues and an attempt was made to use a short Gaussian shaped drive laser to generate the initial beam. This iterative design significantly reduces the length of the photocathode injector and there exists a means of beam cluster pre-compression that improves the beam quality of the accelerator.

Speaker: Cheng Wang (Shanghai Synchrotron Radiation Facility)

16:00 Design of a C band cryogenic copper photocathode RF gun

Ultra-High brightness electron sources are enabling technologies for frontier applications of electron accelerators, such as FEL, UED, and UEM. Due to the higher cathode acceleration gradients and lower initial thermal emittance at cryogenic temperatures, cryogenic copper radio-frequency electron guns have the potential to achieve higher brightness. In this paper, a 2.5-cell C-band cryogenic copper RF gun operating at 77 K has been desinged, which requires the accelerating gradient on the cathode to exceed 180 MV/m. The cavity geometry is automatically optimized in CST to reduce the modified Poynting vector and pulsed heating temperature. A mode converter coupler is applied to maintain the symmetry of the electromagnetic field, which can reduce emittance growth caused by multipole modes. The fabrication of this electron gun has already been started and high-power conditioning is expected to begin in August 2025.

Speaker: Ouzheng Xiao (Institute of High Energy Physics)

16:00 Design of a fully 3D-printed 350MHz-CH-structure

This study presents the design and fabrication of a fully 3D-printed Crossbar H-mode (CH) cavity operating at 350 MHz, optimized for continuous-wave (CW) operation. The cavity is manufactured using a 1.4404-grade stainless steel additive manufacturing process, followed by electrochemical polishing and galvanic copper plating to enhance surface conductivity and reduce power losses. The structure will be tested at the FRANZ accelerator in Frankfurt with a 2 MeV proton beam. The accelerating gradient is designed to achieve approximately 1 MV/m, limited by the available RF-power-amplifier of 2 kW. This research demonstrates the feasibility of integrating additive manufacturing with high-frequency accelerator technology for cost-effective and robust cavity production.

16:00 Design of Pelletron accelerator using novel accelerating tube without gap insulators

A novel modular electrostatic accelerating tube, free from gap insulators, is designed that addresses the limitations of traditional metal-insulator bonded accelerating tubes*, which are costly and prone to damage from high-voltage discharges and beam impacts. This design uses ultra-high vacuum (UHV) as the insulator, with electrodes placed in series under vacuum. High voltage is coupled longitudinally to the first cylindrical electrode via a ceramic-bonded stainless steel flange, with homogeneous electric field flatness of 0.001. Electrostatic analysis using COMSOL Multiphysics and TRAVEL code confirms the field homogeneity and smooth beam acceleration, respectively. Designed for 75 kV operation, extendable to q×100keV energy gains, it leverages vacuum-compatible resistors for inter-electrode HV coupling. Field flatness is extendable to few meters of length and thus enabling megavolts. Beam optics and electrical specifications for Pelletron accelerators using these tubes supports practical feasibility. The grounded cylindrical structure ensures safety and offers an economical, scalable design for small low-energy implanters, Pelletron accelerators, and mass spectrometers.

Speaker: Niketan Jakhar (Jawaharlal Nehru University)

16:00 Developing expectations for AWAKE with simulations

The AWAKE experiment at CERN makes use of a self-modulated proton bunch to excite wakefields and accelerate a witness electron bunch. Run 2c of the experiment will demonstrate stabilization of the wakefield amplitude and control of the witness bunch emittance during injection and acceleration. In this work, we present an overview of the ongoing simulation efforts to support the project as it moves towards controlled acceleration and first particle-physics applications.

Speaker: John Farmer (Max Planck Institute for Physics)

16:00 Development and operational performance of multi-alkali antimonide photocathodes

Multi-alkali antimonide photocathodes, particularly potassium–cesium-antimonide, have gained prominence as photoemissive materials for electron sources in high-repetition-rate FEL applications due to their properties, such as low thermal emittance and high sensitivity in the green wavelength. To explore the potential of these materials in high-gradient RF guns, a collaborative effort was undertaken between DESY PITZ and INFN-LASA to develop and study multi-alkali photocathode materials.
A batch of three KCsSb photocathodes and one NaKSb(Cs) photocathode was grown on molybdenum substrates using a sequential deposition method in the new preparation system at INFN LASA. These cathodes were successfully transferred and tested in the high-gradient RF gun at PITZ. Following the tests, a post-operational optical study was conducted on all the cathodes.
Based on these findings, efforts are underway to optimize the fabrication recipes for KCsSb and NaKSb(Cs) photocathodes to achieve lower field emission and longer lifetimes. This contribution summarizes the experimental results of the production, operational performance, and post-usage analysis of the current batch of cathodes.

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

16:00 Development of FFA at Center for Accelerator and Beam Applied Science of Kyushu University

Center for Accelerator and Beam Applied Science of Kyushu University has been established to promote activities in various fields such as, medical, educational and engineering fields at Kyushu University. An accelerator facility, consist of a 10 MeV proton cyclotron, 8 MeV tandem accelerator and of 150 MeV FFA, has been constructed in the center. In this paper, status of the hardware developments and results of the beam commissioning of the FFA in Kyushu University is described.

Speaker: Yujiro Yonemura (Kyushu University)

16:00 Development of normal conducting heavy ion linac in China

Research on heavy ion linac was began more than ten years ago initially to improve the HIRFL operation at IMP. In China, the first continuous wave (CW) heavy ion linac, SSC Linac, working at 53.667 MHz was designed and constructed as the SSC injector. The ion particles can be accelerated to 1.48 MeV/u with the designed A/q≤5.17. At present stage, this CW linac has been put into operation and the Uranium has been accelerated to 1.48 MeV/u successfully in the end of 2023. To meet the rising requirements of the applications, a compact 162.5 MHz heavy ion linac operating in pulse mode was developed with A/q≤3. The “KONUS” beam dynamics was adopted in the IH-DTL design and the heavy ions can be accelerated to 4 MeV/u in 9m length. The 108.48 MHz SESRI linac was another pulse machine which was built at Harbin. Both of the heavy ions and proton beam can be accelerated by this linac to 2 MeV/u and 5.6 MeV, respectively. In this paper, the status of these three heavy ion linacs and their beam commissioning results were presented.

Speaker: Xuejun Yin (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Development of the capillary discharge plasma source at UCLA

At UCLA, we’ve developed a versatile capillary discharge plasma source for plasma wakefield experiments at the MITHRA and AWA facilities. This compact device, with an adjustable length and a 3-mm aperture, is designed to transmit high-aspect-ratio beams and generate plasmas across a wide density range. Its tunable density allows us to explore the shift from linear to nonlinear plasma wakefield acceleration (PWFA) in detail. Recently, we compared the performance of thyratron and solid-state switches, using an interferometric diagnostic system to measure the resulting plasma densities and these results are presented.

Speaker: Pratik Manwani (University of California, Los Angeles)

16:00 Diagnosing an In-Vacuum Undulator in the ALS storage ring

The Advanced Light Source (ALS) has an in-vacuum undulator named “LEDA”. It was installed in 2019 and provides high-brightness, high-energy photons for the ALS macromolecular crystallography beamline, Gemini. The undulator is a hybrid design with a minimum gap of 4.3 mm, a magnetic period of 15 mm, and a photon energy range of 5–19 keV. When the device was commissioned in the ALS storage ring, it had a negligible impact on ring operations. Recently, there has been a measured degradation in storage ring performance correlated with the Leda gap. Prior to conducting an invasive magnetic measurement, we performed a suite of beam-based measurements to characterize Leda. Herein, we detail these measurements and share them with the accelerator community, who may find them useful when encountering similar challenges.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

16:00 Effects of the transverse plasma gradient in the plasma wakefield accelerator

We present basic analytical studies on the effects of the local transverse plasma density fluctuations. We show that in two acceleration schemes (blow-out regime and hollow plasma channel) transverse plasma density gradient results in a transverse wakefield. This, in turn, may lead to significant limitations in the machine's performance. We consider the classical round driver in the transverse coordinates and show, that in the blow-out regime transverse plasma inhomogeneity results in the dipole wake that may deflect the driver and result in housing instability. We show that in the case of a hollow plasma channel, transverse plasma gradient shifts the electromagnetic center of the plasma channel. As a remedy, we propose to consider flat driver injection and show, that a flat driver in the blow-out regime can be robust to the perturbation in transverse plasma density.

Speaker: Stanislav Baturin (ITMO University)

16:00 Electron beam scattering in rubidium vapour at AWAKE

The Advanced Wakefield Experiment (AWAKE) at CERN uses bunches from the CERN SPS to develop proton-driven plasma wakefield acceleration. AWAKE Run 2c (starting in 2029) plans for external on-axis injection of a 150 MeV electron witness bunch. The goal is to demonstrate emittance control of multi-GeV accelerated electron beams. Prior to injection, the electron witness bunch may have to traverse rubidium vapour. Since the beam must have the correct beam size and emittance at injection, it is important to quantify the effect of scattering. For this, first-principle estimates and the results from Geant4 simulations are compared with measurements of a ~20 MeV electron beam scattering in 5.5 m of rubidium vapour, showing good agreement. Building on this agreement, Geant4 simulations using the estimated AWAKE Run 2c parameters are performed. These predict that scattering will not increase the electron beam size or emittance

Speaker: Fern Pannell (University College London)

16:00 Electron cyclotron resonance accelerator for industrial radiation processing

Industrial radiation processing is used on a wide variety of products, including medical devices for eradication of pathogens, food for preservation and safety, and plastics for material property modification. But millions of curies of Co-60 that are still used in some industrial sterilization facilities can pose a significant security risk in an act of radiological terrorism. Lower-cost electron beam systems with high beam-power efficiency and high reliability are needed to replace Co-60 based sterilization systems. A novel accelerator under development, electron Cyclotron Resonance Accelerator (eCRA) is described here. It is highly compact and efficient to produce high power electron beams and x-ray beams. The several attractive features of eCRA include: a compact robust room-temperature single-cell RF cavity as the accelerator structure; continuous ampere-level high current output without bunching; and a self-scanning accelerated energetic e-beam, obviating need for a separate beam scanner. Details of design and predicted performance will be described.

Speaker: Yong Jiang (Particle Accelerator Research Foundation)

16:00 Electrostatic deflector Nuclotron modernization for EDM experiment

Considered the current Nuclotron structure for precision EDM-experiments as an independent synchrotron storage ring equipped with electrostatic deflectors. In this regard, the design must ensure the preservation and precise regulation of spin dynamics stability. Moreover, the initial purpose of the structure as a booster of polarized beams in the collider has been preserved.

Speaker: Aleksei Melnikov (Russian Academy of Sciences)

16:00 Experimental demonstration of terahertz transport using overmoded iris-line waveguide

The need for THz pulses with 100 µJs of pulse energies at a 100 kHz (or higher) repetition rate that are well synchronized with X-ray free electron laser (XFEL) pulses is paramount to studying novel ultrafast phenomena. Efficient THz generation (3 – 20 THz), coupling, and transport over long distances has posed several challenge. In particular, THz wavelengths makes it impractical to rely on metal waveguide for long distance transport, while free space propagation is prone to strong diffraction. In addition, water absorption causes significant attenuation to THz propagation. We present a tabletop experiment to demonstrate efficient transportation of THz radiation at 3.25 THz using metallic irises. This experiment demonstrates efficient transport of THz radiation over 20 meter distances which notable behavior of slower attenuation compared to free space propagation.

Speaker: Mohamed Othman (SLAC National Accelerator Laboratory)

16:00 Extreme radiation from electron beams in ion channels and undulators

We compare radiation from relativistic electrons (γ≫1) in magnetic undulators and ion channel betatron oscillations, addressing limitations in conventional theories for high undulator parameter (K) and K/γ regimes. Differences in magnetostatic and electrostatic oscillations lead to inaccurate trajectory and radiation descriptions. By reformulating key parameters, we enable comparisons of equivalent oscillation conditions and analyze distinct spectral features via numerical simulations. A novel transverse orbit precession effect in ion channels, significant for particles with initial angular momentum, is identified and shown to impact radiation divergence and beam emittance. Theoretical predictions are validated through simulations, providing insights for experimental applications.

Speaker: Dr Monika Yadav (University of California, Los Angeles)

16:00 Fast greens experiment program status at FERMI IOTA/FAST facility

In this paper we will report on the recent progress made on FAST-GREENS experiment program at IOTA/FAST facility at Fermilab. FAST-GREENS experiment will take advantage of the superconduct LINAC in IOTA/FAST facility. A 4 m-long strongly tapered helical undulator with a seeded prebuncher is used in the high gain TESSA regime to convert a significant fraction (up to 10 %) of energy from the 240 MeV electron beam from the FAST linac to coherent 515 nm radiation. We will report the progress of the preparation for this experiment, which includes the preparation work for the beamline, the preparation work for laser development and characterization work, and the design and installation of the laser transport system. We will also discuss the future timeline for the program.

Speaker: Jinhao Ruan (Fermi National Accelerator Laboratory)

16:00 Femtosecond laser-induced plasma filaments for beam-driven plasma wakefield acceleration

Plasma-based acceleration technology can revolutionize particle accelerators, enabling the realization of compact systems capable of driving different user-oriented applications.
We propose developing a laser-based, high repetition rate (HRR), highly stable and tunable plasma filament stage for beam-driven plasma wakefield acceleration (PWFA) systems. The plasma filament, generated by a low-energy self-guided femtosecond laser pulse, is studied experimentally and theoretically in a low-pressure N2 gas environment.
Precise control of the plasma filament is crucial for plasma-based accelerators, and different techniques have been implemented to measure its density, temperature and dimensions. The measurements show the stable generation of a ≈4cm long channel with a ≈300μm diameter. The plasma density and temperature are ne≈1016cm−3 and Te≈1.3eV with a decay time of ≈8ns.
Compared to other plasma stages in PWFA configurations, the proposed one allows for inherently synchronized stages at HRR. The hundreds-µm transverse structure size extends the stage lifetime, and the highly tunable parameters allow us to explore different scenarios. This technology can provide GeV-level electrons at HRR in a compact space, maintaining the high quality and brilliance of the LINAC-generated beams. This development aligns perfectly within the goals of the EuPRAXIA European project.

Speaker: Mario Galletti (Istituto Nazionale di Fisica Nucleare)

16:00 First beam through the superconducting linac of European Spallation Source

The European Spallation Source (ESS), currently under construction in Lund, Sweden, is designed to be the brightest neutron source in the world. It will be driven by a superconducting proton linac with a design beam power of 5 MW and energy of 2 GeV. The construction and installation of the linac are completed for the initial user operation envisaged in 2026 with capability of 2 MW beam power and 800 MeV energy. Beam commissioning of the full linac up to the dump in the line of eyesight is planned in early 2025. At this stage, the main focus will be on establishing optimal transport of 800 MeV beam as well as validating the critical components such as the RF system, diagnostics devices and machine protection systems. This contribution presents the highlights from this commissioning phase that will send the beam through the superconducting linac of ESS for the first time.

Speaker: Ishkhan Gorgisyan (European Spallation Source)

16:00 Force-neutral adjustable phase undulator array for compact FELs and multiline FEL facilities

The Force-Neutral Adjustable Phase Undulator (FNAPU) is set to revolutionize future free-electron laser (FEL) undulator designs. This innovative technology is gaining rapid traction as its compact and lightweight design offers a cost-effective solution for X-ray production. The FNAPU can be efficiently scaled to lengths of 5 meters and beyond and meet the requirements for light production with specific polarizations. Their multiplexing capability is especially beneficial for covering a wide photon energy range and enabling multiple X-ray beams, making them ideal for diverse scientific and industrial applications such as FELs for extreme ultraviolet (EUV) lithography in semiconductor fabrication and X-ray FELs that require small-period undulators.

Speaker: Joseph Xu (Argonne National Laboratory)

16:00 Force-neutral adjustable phase undulators

Variable gap undulators require large and complex motion systems to operate, making their tunability to generate specific radiation wavelengths cumbersome, limited, and slow. RadiaBeam Technologies is engaging in a project to advance undulator manufacturing by utilizing force-neutral adjustable phase undulator (FNAPU) technology developed by Argonne National Laboratory (ANL). This innovative approach allows high precision undulators to be more compact, cost-effective to fabricate and assemble, and safe and user friendly in alignment, manipulation and operation.

The innovation of FNAPU technology is based on the inclusion of a secondary array of permanent magnets, arranged to compensate the internal forces brought on by the main undulator array. The flexibility and compact design of FNAPUs allows for exotic applications (X-undulators) and multiple FNAPUs can be packed together to form an undulator matrix, covering extensive X-ray energy ranges and a broad range of applications, relevant to the needs of XFEL and SR communities, and beyond.

Speaker: Yung-Chuan Chen (RadiaBeam Technologies (United States))

16:00 Generation of THz coherent undulator radiation by velocity bunching of electron beam

We experimentally study the generation of THz coherent undulator radiation by electron beam at NTHZ facility which is located in USTC. Velocity bunching scheme in a travelling-wave accelerating structure is employed to produce the short electron bunch. An undulator which has 20 periods with a period length of 5.8cm and a maximum undulator parameter of 3.95 has been developed to produce intense coherent THz radiation.

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

16:00 Hands on training with ASTRA at ISBA'24

As part of the program of the seventh International School on Beam Dynamics and Accelerators (ISBA'24), we carried out hands-on training with the accelerator simulation code ASTRA. A selection of students used the intensive two-hour daily course to go from learning the basics of ASTRA to designing and optimizing their own accelerators. Here we report the details of training, the student projects and their presentations to their instructors and peers, and plans for future hands-on training programs.

Speaker: Zachary Liptak (Hiroshima University)

16:00 Helical undulators assembled from magnetized ring sectors

Undulators assembled from quasi-helices consisting of readily available magnetized ring rare-earth sectors are proposed. "Radially" magnetized sectors create a stronger field on the axis than longitudinally magnetized ones. The field value weakly depends on the number of sectors per undulator period. An experimentally studied prototype Halbach-type helical undulator of "radially" and longitudinally magnetized quasi-helices consisting of ring NdFeB sectors with a period of 2 cm and a comparatively large inner diameter of 8 mm provides a field of about 0.6 T on the axis. By reducing the inner diameter to 5 mm, it is possible to obtain a field twice as large. When assembling such an undulator, it is convenient, while maintaining the positions of all ring sectors, to use a division of the undulator not into quasi-helices, but into cylindrical sectors shifted along the axis and rotated relative to each other. Permanent undulators from ring sectors can provide a higher velocity of transverse electron oscillations than planar ones, and therefore seem promising for increasing the efficiency of FELs in various frequency ranges.

Speaker: Nezah Balal (Ariel University)

16:00 High efficiency muonium beam source

A highly efficient muonium source will enable fundamental muon and precision measurements, including sensitive symmetry-violation searches. There are no U.S. muonium sources, nor available muon beams. Muonium sources internationally are significantly oversubscribed. The intense 800 MeV PIP-II linac under construction at Fermilab is capable of providing world-class muon and muonium beams with unparalleled intensity to drive the next generation of precision muon-physics experiments at the intensity frontier. Timing is critical to initiate the prerequisite R&D necessary to prepare for the PIP-II era. This paper describes a muonium beam for experiments such as measurement of antilepton gravity and improved searches for muonium–antimuonium mixing. The low-energy µ+ and µ─ beams can also support muon spin-rotation applications to material science including critical surface studies of quantum computing devices, precision muon experiments, muon-cooling studies for a future muon collider, muon-catalyzed-fusion R&D, and unique studies of semiconductor device physics.

Speaker: Daniel Kaplan (Illinois Institute of Technology)

16:00 Hose instability suppression by bunch anharmonic oscillations in weakly non-linear regime in wakefield accelerator

Acceleration by plasma wakefield accelerators enables compact sources of high-brightness relativistic electron bunches. Applications like free electron lasers and particle colliders require high efficiency and low energy spread, achievable in the blowout regime, where the radial wake force is linear and independent of the longitudinal coordinate over much of the wakefield bubble. However, this regime introduces hose instability due to harmonic oscillations of electrons in the bunch. Studies show that anharmonic oscillations, caused by inhomogeneous focusing force along the wakefield bubble, suppress this instability. In the weakly nonlinear regime, where some plasma electrons remain in the bubble, their inhomogeneous density widens the stability region. Radial inhomogeneity in the residual plasma electron distribution further leads to anharmonicity of oscillations, stabilizing the bunch. We evaluated the oscillation period and found that the large radial and longitudinal gradients of the focusing force in the driver and witness bunch regions satisfy stochastic stabilization conditions. This enhances the stability of both bunches.

Speaker: Ilia Demydenko (V. N. Karazin Kharkiv National University)

16:00 Implementation of novel acceleration functionality in BDSIM

Beam Delivery Simulation (BDSIM) is a Geant4 based accelerator tracking code which includes interactions of particles with material. BDSIM has become an important code in the accelerator community to simulate beam lines. Since laser and beam driven plasma wakefield acceleration (LWFA/PWFA) is a promising acceleration method we found it important to include related capability in BDSIM. This requires the addition of new beamline elements that are commonly used in plasma acceleration experiments. A gas volume where the LWFA/PWFA takes place and a beam mask to create a separate drive beam and a witness beam. In the former, the beam interacts with gas so ideal gas calculations are required to input the gas properties. Biasing can specifically be applied to the gas material in those elements. Simulating the interactions between the beam and a plasma is not done in BDSIM. An external software is used to compute the fields and the particles data. BDSIM can now read the output HDF5 files to reconstruct the fields inside the gas capillary or use the particle data as a bunch definition for the beginning of a beamline. Some results explaining how to make a LWFA/PWFA simulation are presented.

Speakers: Marin Deniaud (Cockcroft Institute), Stewart Boogert (Cockcroft Institute)

16:00 Improvement of electron beam properties for Few-TW LWFA conducted in a sub-mm gas cell filled with a helium-nitrogen mixture

Developing a laser wakefield acceleration (LWFA) scheme by focusing few-TW laser pulses into a thin, dense gas target paves the way for generating high-average-current electron beams driven by a modern high-repetition-rate laser. Our previous study demonstrated that using a sub-mm nitrogen (N₂) gas cell facilitates the routine generation of 10-MeV-scale electron beams from few-TW LWFA with ionization-induced injection. However, excessive ionization-induced defocusing of the pump laser pulse tends to occur in an N₂ target, motivating the use of a helium (He) – nitrogen (N₂) mixture as the gas target to mitigate pump pulse defocusing in few-TW LWFA*. In this study, the effect of nitrogen doping ratio ranging from 0.5% to 5% was investigated using 40-fs, 1-TW pulses with a 0.4-mm-long gas cell. We found that a manifest peak repeatedly appears around 10 MeV in the energy spectra with the 99.5% He - 0.5% N₂ gas mixture - a result never observed with the pure N₂ cell. Using the He-N₂ mixture also leads to a noticeable increase in the charge of high-energy electrons (>5 MeV) and a reduction in the pointing fluctuation of the output beams compared to the pure N₂ target.

Speaker: Po Wei Lai (National Tsing Hua University)

16:00 Investigations on H-mode drift tube linac structures in the ultra-high frequency range

This study deals with the design and performance analysis of H-mode drift-tube linac (DTL) accelerators in the ultra-high frequency (UHF; 0.3 - 3 GHz) range. Simulations of typical application scenarios were performed, including particle velocities from 0.05c to 0.25c and different drift-tube internal structures. The RF efficiency of different H modes was analyzed. In addition to the shunt impedance, the field distribution and the thermal load also play a role.

Speaker: Eduard Boos (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Ion-motion simulations of a plasma-wakefield experiment at FLASHForward

In plasma-based acceleration, an ultra-relativistic particle
bunch—or an intense laser beam—is used to expel electrons
from its propagation path, forming a wake that is devoid
of electrons. The ions, being significantly more massive,
are often assumed to be stationary. However, both theory
and simulations suggest that any sufficiently dense electron
bunch can trigger ion motion, and its effect must be taken
into account. We simulate beam-driven plasma wakefields
to identify key features—such as longitudinally dependent
emittance growth—that could be observed in an experiment
using plasma and beam parameters from the FLASHForward
facility at DESY.

Speaker: Daniel Kalvik (University of Oslo)

16:00 Key issues in the high intensity beam commissioning for the CSNS RCS

Speaker: Ming-Yang Huang (Institute of High Energy Physics)

16:00 Laser-based cleaning of phocoathode at SXFEL

The Shanghai soft X-ray Free-Electron Laser user facility has open to users since 2023. The electron beam is generated by Cu photocathode, integrated in an S-band electron gun. As the photocathode quantum efficiency drops to less than 10^-5, photocathode cleaning technology based on drive laser is used to improve the performance of the photocathode.

Speaker: Zenggong Jiang (Shanghai Advanced Research Institute)

16:00 Low energy beam transport line design for the Sarajevo ion accelerator

The University of Sarajevo Physics Department, in collaboration with CERN’s Accelerator Beam Physics group, proposes a compact linear accelerator design for applied physics research spanning from beam dynamics studies to material surface analysis. The Sarajevo Ion Accelerator (SARAI) consists of an electron cyclotron resonance ion source, a low energy beam transport line (LEBT) and a radiofrequency quadrupole (RFQ). The ion source can produce an array of ions extracted with 30 kV. This study presents an iterative parameter optimization method that suggests two LEBT optics: one for beam diagnostics and another for compact beam matching to the RFQ acceptance. The RFQ discussed here is a 750 MHz, 2.5 MeV/u RFQ, used for medical applications. SARAI RFQ aims at 0.5 - 2 MeV/u. A novel RFQ technology allows a significant reduction in footprint. This paper further discusses plans for source commissioning and potential research applications.

Speaker: Amer Ajanovic (European Organization for Nuclear Research)

16:00 Low-power test of bridge coupler 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 electric dipole moment (EDM). A 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 is currently being fabricated and will be tested. This paper presents the design and performance evaluation of the bridge coupler prototype.

Speaker: Ayaka Kondo (Nagoya University)

16:00 Magnetic cycle optimisation in the CERN PS booster

The PS Booster is the first synchrotron in the CERN proton accelerator complex, which delivers both high-brightness and high-intensity beams. Injection to the Booster is at a kinetic energy of 160 MeV, therefore space charge is a main limiting factors for beam quality. Maximising the longitudinal emittance and adding a second, and sometimes third, RF harmonic are measures to decrease the line density and so reduce the effect of space charge. Nonetheless, beam loss and transverse emittance growth are still unavoidable at low energy. Recent studies have been focused on the possibility of adapting the magnetic cycle to further reduce the impact of space charge. With a faster ramp, the time spent in a high space charge regime is reduced but the available RF voltage limits the bucket area. Alternatively, with a slower acceleration the RF bucket area and longitudinal emittance can be increased, which will reduce the magnitude of the space charge detuning, but more time will be spent at low energy. This contribution explores the effects of different magnetic cycles on the beam and the possibility of further optimising the booster acceleration.

Speaker: Simon Albright (European Organization for Nuclear Research)

16:00 Mechanical design of a spin rotator for the ISIS Super MuSR beamline

The Super MuSR spin rotators (SR) are electromagnetic devices with a horizontal dipolar magnetic field to rotate the muon spin by 34o and a perpendicular electric field that operates at +/-192 kV. The electromagnetic design was already presented elsewhere. The mechanical design is now complete, and the manufacturing of components has started, both of which are discussed here. The stainless steel vessel is 598 mm in diameter, 1.8 m long and has several ports along it. Most notably the large feedthrough port with a 15 mm inner radius to reduce the electrical fields. Mirror polished electrodes are mounted on ceramic insulators, optimised to shield the triple points from the high electric fields. The insulator mechanical design, manufacture & testing will also be discussed here. A high voltage test rig has been developed in parallel to test critical aspects such as the high voltage feedthrough, insulator design, vessel manufacture and surface finish requirements, before testing and assembling the main vessel. The magnet yoke is H-shaped with traditional racetrack coils. It was designed to be assembled around the around the vacuum vessel with kinematic feet for adjustment and alignment.

Speaker: Jonathan Cawley (Science and Technology Facilities Council)

16:00 Modeling and evaluation of plasma channel systems for laser plasma accelerators

Structured plasma channels are an essential technology for driving high-gradient, plasma-based acceleration and control of electron and positron beams for advanced concepts accelerators. Laser and gas technologies can permit the generation of long plasma columns known as hydrodynamic, optically-field-ionized (HOFI) channels, which feature low on-axis densities and steep walls. By carefully selecting the background gas and laser properties, one can generate narrow, tunable plasma channels for guiding high intensity laser pulses. We present on the development of 1D and 2D simulations of HOFI channels using the FLASH code, a publicly available radiation hydrodynamics code. We explore sensitivities of the channel evolution to laser profile, intensity, and background gas conditions. We examine experimental measurements of plasma channels and their comparison to model predictions. Lastly, we discuss ongoing work to couple these tools to community PIC models to capture variations in initial conditions and channel influence on wakefield accelerator applications.

Speaker: Nathan Cook (RadiaSoft (United States))

16:00 Multi-physics analysis of a 280 MHz superconducting radio-frequency quadrupole test cavity

Superconducting(SC) radio-frequency(RF) quadrupole (RFQ) integrates the high efficiency of SC technology with the strong focusing and stable acceleration capabilities of RFQ .It is a critical development in next-generation high-performance accelerators.In this study, we present the multi-physics analysis results of a SC RFQ test cavity operating at a frequency of 280 MHz. This test cavity is designed to be a constant voltage of 240 kV and can be used to accelerate a 10 mA proton beam. The RF design adopts a four-vane structure, which is both structurally stable and facilitates efficient liquid helium cooling. Multi-physics analysis indicates that the cavity deformation and thermal stress meet the operational requirements after the post-treatment of the electrodes.The SC RFQ holds significant potential in many areas, including medical isotopes,particle physics experiments,Boron Neutron Capture Therapy (BNCT) and Proton Therapy. Because of the low operational costs and compact structure, it provides an possibility to enable industrialization and applications of high-power accelerators.

Speaker: Junzhao You (Peking University)

16:00 NLCTA and the X-band Test​ Area at SLAC

The Next Linear Collider Test Accelerator (NLCTA) facility at SLAC National Accelerator Laboratory provides unique capabilities for conducting accelerator research and testing technology with accelerator applications, as well as beam time for experiments using the X-band Test Accelerator (XTA). Test areas in the facility support high power RF testing over a range of frequencies and operating temperatures, allowing for a broad range of ongoing research programs. Experiments include irradiation studies, high gradient accelerator testing, superconducting materials testing, detector testing, prototype development for medical applications like proton therapy for cancer treatment, and electron beam diagnostics using THz streaking. This variety in research topics takes advantage of the NLCTA's flexible infrastructure and wide range of in-house expertise. Facility capabilities and highlights from the active experimental program are presented here.

Speaker: Ankur Dhar (SLAC National Accelerator Laboratory)

16:00 Novel deuteron accelerator for nuclear waste transmutation

Accelerator-driven systems (ADSs) can accelerate high intensity ions to generate high flux of neutrons to transmute the long-lived species in used nuclear fuel (UNF) from nuclear reactors. A typical specification would be for a 1-2 GeV proton beam, comprising multi-MW-level power load on a spallation target. An alternative approach could be to produce the neutrons via breakup of 40-MeV deuterons on a low-Z target. For this purpose, an innovative deuteron cyclotron auto-resonance accelerator dCARA is described here. It is predicted to produce a 40-MeV, 125 mA CW deuteron beam, with notable features including continuous acceleration without bunching for good beam stability, high efficiency, wide beam aperture, and an exceptionally short length of 1.6 meters. It is estimated that 5-10 smaller ADS dCARA-based modules could provide the same level of transmutation as one ADS employing a GeV-level 25-MW linac. Other applications of dCARA include medical isotope production system, or fusion prototypic neutron source for testing inner-wall materials for a future fusion power reactor.

Speaker: Yong Jiang (Particle Accelerator Research Foundation)

16:00 Optical and laser systems for the AWAKE run 2C experiment

In the AWAKE Run 2c experiment, two electron beams are injected into two separate rubidium (Rb) vapour sources. The first electron beam initiates the self-modulation of a proton bunch in the first vapour source, while the second electron beam serves as a witness beam for plasma wakefield acceleration with low energy spread in the second vapour source. This setup requires the precise spatio-temporal delivery of four laser beams: two deep UV beams that generate the electron beams with a relative timing jitter well below 100 fs, and two near-IR beams that ionize efficiently the Rb vapour sources. The UV pulses are generated by an established Yb laser system, capable of producing 400 uJ, 0.2-10 ps pulses at 257 nm with high reliability (<0.1% RMS energy fluctuation), and enables emittance optimization via spatial beam shaping. The same system is used for both electron sources, utilizing a partial reflector to split the beam and account for differing photocathode yields. For the Rb ionizing pulses, which are directed into the vapour sources in a counter-propagating geometry, the pulses from the AWAKE Ti:Sapphire laser system are transported using a series of vacuum relay telescopes.

Speaker: Vlad Musat (European Organization for Nuclear Research)

16:00 Optimization of a multichannel solid state plasma for laser wakefield acceleration with realistic laser parameters using a Bayesian algorithm

Nanostructures based on carbon nanotube arrays are emerging as promising media for achieving ultra-high acceleration gradients in laser wakefield acceleration (LWFA). In this study, we design and optimize plasmas with hexagonal lattice structures, where the lattice parameters directly define the nanostructure's properties. Using WarpX, a state-of-the-art particle-in-cell (PIC) simulation framework, we conduct fully three-dimensional simulations to model the interaction between these advanced plasmas and laser pulses. To refine the lattice parameters, we apply Bayesian optimization through the Python library BoTorch, identifying optimal configurations for generating effective wakefields. These results are intended to guide preliminary simulations for future experiments at leading laser facilities, such as ELI and VEGA3, advancing the exploration of LWFA with nanostructured plasmas.

Speaker: Beatriz Higuera Gonzalez (University of Manchester)

16:00 Optimization of eletron beam brightness in the photoinjector of the European XFEL

Photoinjector performance is a key to accessing to the sub-angstrom operation regime of the European XFEL. Optimization of the photoinjector determines the lowest possible emittance along the long accelerator beamline, thus strongly influencing the lasing performance at a given electron beam energy and undulator settings of the user facility. In this paper, an injector optimization approach is established based on a semi-analytical model. It aims at achieving the maximum achievable brightness of the extracted electron beams from the photocathode, taking into account multiple cathode laser properties and gun operation parameters. The semi-analytical predictions are compared with conventional simulation results for an extended parameter range of the European XFEL injector. The obtained results will be presented and discussed.

Speaker: Meng Cai (Deutsches Elektronen-Synchrotron DESY)

16:00 Optimization of the driver energy deposition in plasma wakefield acceleration simulations by varying transverse offset of sextupole magnets

Plasma Wakefield Acceleration (PWFA) is a method of accelerating charged particles using a plasma. It has the potential to produce exceptionally large accelerating gradients on the order of 10’s of GeV/m. The FACET-II test facility accelerates pairs of 10 GeV electron bunches to study the PWFA process—a drive bunch to produce a wake in the plasma in a lithium-ion oven, and a witness bunch to be accelerated by PWFA. By using arrangements of sextupole magnets, it is possible to alter the chromaticity and other energy-dependent properties of the beams prior to their entry into the plasma. The purpose of this study was to determine how the transverse offsets of the sextupole magnets could be optimized to increase the amount of energy deposited into the plasma by the drive bunch as this energy deposition is critical to maximising the efficiency of PWFA. To achieve this, a simulation of the FACET-II beamline was performed with sextupole offsets as adjustable parameters in a Bayesian Optimization procedure. The results demonstrate the value of using beam simulations as guides to improve the PWFA process, thereby reducing the need to perform costly experiments at the FACET-II facility.

Speaker: Mason Stobbe (SLAC National Accelerator Laboratory)

16:00 Packaged photocathodes for X-ray free electron lasers

Alkali photocathodes are vital for generating high-performance electron beams in accelerator technologies, but their production remains challenging. Current in-house fabrication methods are complex, costly, and unreliable, limiting the potential of these materials for bright electron sources. Our innovative approach seeks to commodify photocathodes, offering a ready-to-use product for accelerator facilities and scientific institutions. We use a proprietary sputtering process with in-house-manufactured bulk targets, ensuring consistent quality and streamlined production. Unlike traditional vacuum suitcases, which are heavy and require active power, our photocathodes are stored in portable, palm-sized vacuum canisters that maintain vacuum without power. This design preserves their integrity during transport and handling, addressing their extreme sensitivity to air and moisture, which demands ultra-high vacuum protection. By delivering pre-fabricated, protected photocathodes, we eliminate the need for facilities to invest in specialized equipment, enabling broader adoption and reducing downtime. Our work paves the way for accessible, affordable, and readily available photocathodes.

Speaker: Harish Bhandari (Radiation Monitoring Devices (United States))

16:00 PEEK-Polymer as a vacuum-window in high power rf-couplers

PEEK is an advanced polymer known for its exceptional mechanical strength, thermal stability, and radiation resistance, making it a promising candidate for applications in extreme environments. This study explores the viability of PEEK as a vacuum window material in high-power radio frequency (RF) couplers. Traditionally, materials such as ceramics are employed for this purpose; however, they are costly to manufacture and impose limitations during the design process. PEEK offers additional advantages, including the possibility of additive manufacturing, which enables the integration of cooling channels for efficient thermal management. The research evaluates PEEK's electrical, thermal, and mechanical properties under conditions typical of high-power RF couplers, such as vacuum stability, RF-induced heating, and electromagnetic transparency. At the Institute for Applied Physics (IAP), PEEK is tested as a vacuum window material in high-power experiments up to 35 kW. Following these tests, the material is analyzed to assess its performance and suitability for RF applications.

Speaker: Klaus Kümpel (Goethe University Frankfurt)

16:00 Permanent hybrid helical micro-undulators for FELs and inverse FELs

High-field micro-undulators are one of the key elements in most compact Terahertz and X-ray FEL projects. In our works, helical undulators of several helices, each made of a single piece of rare-earth magnet, are proposed for this purpose. We demonstrated previously the possibility of high-precision manufacturing helices with centimeter periods using the Wire Electric Discharge Machining. In this paper, we will discuss an experimental prototype micro-undulator of two oppositely longitudinally magnetized NdFeB helices with a period of 6 mm and an inner hole diameter of 1 mm, creating a transverse field close to 1 T. The magnitude of the field and/or the inner diameter of the helices can be significantly increased by using hybrid systems with two longitudinally pre-magnetized rare-earth and two pre-unmagnetized steel helices. We are currently developing methods for manufacturing, assembling and measuring the parameters of such systems with periods of 6 and 3 mm and a field of 1 T and will demonstrate the corresponding results in the presentation.

Speaker: Eyal Magory (Jerusalem College of Technology)

16:00 Plasma generation in capillary discharges simulated with COMSOL for charged particle acceleration

This study develops a gas-filled plasma-discharge capillary system for laser wakefield acceleration (LWFA). Using an external high-voltage source for pre-ionization enhances plasma formation, operational stability, and laser propagation over extended Rayleigh lengths, enabling high-energy electron beams. The uniform plasma environment improves beam charge, consistency, and energy spread, allowing efficient generation of 250 MeV very-high-energy electron (VHEE) pencil beams in a compact system. Designed at the upcoming I-LUCE facility in Catania, Italy, the setup supports VHEE and FLASH radiotherapy (FLASH-RT) research. COMSOL Multiphysics simulations of plasma density variations validate the model's accuracy and its potential for optimizing plasma-based LWFA systems.

Speaker: Sahar Arjmand (Istituto Nazionale di Fisica Nucleare)

16:00 Preliminary study of beam dynamics for SDTL-Based 200 MeV energy upgrade of KOMAC proton linac

Korea Multipurpose Accelerator Complex (KOMAC) proposes an energy upgrade of the 100 MeV proton linac. The design of the extended linac is based on a normal-conducting separated-DTL (SDTL) structure which has several advantages over other accelerating structures. The SDTL structure is the same as the DTL, however, unlike the general DTL, the quadrupole magnet is not placed inside the DT but is placed outside. This adds more flexibility to optimize the DT structure for better accelerating efficiency. In addition, since only 4 DTs are placed in the SDTL tank, a separated field gradient stabilization device is not needed, so it is known to be easier to manufacture and align than the general DTL. Our upgrade design consists of a beam matching section between the SDTL and the existing DTL, and 20 SDTL tanks each containing four drift tubes (DTs) with a doublet focusing lattice structure. Beam dynamics simulations were performed using an optimized DT structure to accelerate proton beams from 100 to 200 MeV. We report the preliminary beam dynamics study of the 200 MeV SDTL linac carried out at KOMAC.

Speaker: Seunghyun Lee (Korea Multi-purpose Accelerator Complex)

16:00 Preliminary test of the MeV ultrafast electron diffraction instrument at e-labs

The injector test facility for PAL-XFEL project has been evolved into R&D facility named e-labs, where a preliminary test of MeV ultrafast electron diffraction (UED) was carried out. MeV-UED provides similar scientific opportunities as femtosecond time-resolved XRD experiments at XFEL facilities, and would be a useful tool to overcome a limited beam time problem of XFEL. MeV-UED is a pump-probe experiments required high stability to see a small difference in femtosecond time scale. In e-labs, experimental tests for routine operation and improving S/N ration has been studied

Speaker: Chang-Ki Min (Pohang Accelerator Laboratory)

16:00 Present status of RF system upgrade in the J-PARC MR

J-PARC MR delivers 30 GeV proton beams to the neutrino facility and the hadron experimental facility, and an upgrade plan is underway to increase beam power by shortening the MR cycle time and increasing the number of particles per bunch. As a result, the beam power for neutrino experiments has achieved its original design value of 750 kW in 2023 and reached 800 kW in 2024. The target beam power of this upgrade plan is 1.3 MW for the Hyper-Kamiokande experiment.The current RF system consists of 9 fundamental cavities and 2 second harmonic cavities for a total of 11 RF systems, but it is necessary to add two more fundamental cavities to further shorten the MR cycle time. Preparations are underway to begin operation of the 10th RF system in 2025 and the 11th in 2027. In addition, as the number of particles increases, further beam loading compensation will be required, so we are also working on upgrading the RF source. We present the progress of the MR RF system upgrade.

Speaker: Katsushi Hasegawa (High Energy Accelerator Research Organization)

16:00 Progress in Linac Beam Commissioning for High-Intensity Operations for J-PARC Power Upgrades

The Japan Proton Accelerator Research Complex (J-PARC) has achieved stable 1 MW operation test on its neutron target and is advancing toward higher power levels of 1.5 MW to support high-power MR operations and a second target station. This progression presents challenges, including increased intra-beam stripping (IBSt) of H⁻ ions, chop leakage from higher beam currents and emittance, low-energy beam loss due to halo formation, frontend fluctuations affecting beam transmission, and RF phase and amplitude fluctuations. To address these issues, a redesigned lattice mitigates IBSt, a new MEBT1 improves chopping and collimation, and machine learning-based compensation schemes manage frontend and RF fluctuations. Additionally, longitudinal and transverse matching schemes enhance beam quality, validated through benchmarked longitudinal measurements. Results from studies at 50 mA and 60 mA beam currents demonstrate significant progress in overcoming these challenges.

Speaker: Yong Liu (High Energy Accelerator Research Organization)

16:00 Progress on infrared/terahertz free-electron laser and ultrafast laser facility at Chiang Mai University

An accelerator-based mid-infrared (MIR) and terahertz (THz) free-electron laser (FEL) light source has been developed at Chiang Mai University, Thailand, along with experimental stations for high-field irradiation, spectroscopy, and ultrafast interaction studies. The 25-MeV linear accelerator system, serving as the electron beam injector, has been extended to support two newly developed MIR/THz FEL beamlines. Engineering and construction of the magnetic bunch compressors and FEL components were based by physics design and essential beam dynamic simulations. Currently, the commissioning of the accelerator system and its beamlines is underway. Integrated with femtosecond Ti-sapphire laser technology, the facility aims to be a user-accessible ultrafast IR/THz laser facility in Thailand. Offering cutting-edge tools for spectroscopy, imaging, and irradiation, it supports advanced research in material science, biotechnology, and medicine while serving as a training center for accelerator and ultrafast laser technologies. This unique facility will become a regional pioneer in the future.

Speaker: Phanthip Jaikaew (Chiang Mai University)

16:00 Progress on the flat beam PWFA experiment at AWA

A wakefield experiment at the Argonne Wakefield Accelerator (AWA) facility employs flat electron beams with highly asymmetric transverse emittances to drive plasma wakefields in the underdense regime. These beams generate elliptical blowout structures, leading to asymmetric transverse focusing forces. The experiment features a compact 4-cm-long capillary discharge plasma source developed at UCLA. Analytic models of blowout ellipticity and matching conditions, validated by particle-in-cell simulations, inform the experimental design. Key engineering preparations, including vacuum-gas separation windows, beam transport systems, and diagnostics, are detailed. Initial beam runs focusing on flat beam generation and transport are also presented.

Speaker: Pratik Manwani (University of California, Los Angeles)

16:00 Proton-driven plasma wakefield acceleration for high-energy lepton beams

Future colliders with discovery potential for particle physics rely on increasing the parton centre of mass (pCM) energy, with the recent P5 report calling for a 10 TeV pCM collider. However, the development of such schemes using conventional accelerator technology would result in ever-larger facilities. High-gradient plasma wakefields driven by proton beams allow the transfer of energy to a witness bunch over a short length scale, and so offer a potential method to transform high-energy proton beams into high-energy lepton beams while requiring relatively little additional civil engineering.

The application of this concept to a Higgs factory driven by 400 GeV protons was recently proposed. In the present work, we discuss the ongoing efforts to address the challenges to realising such a scheme*, and possible upgrade paths to particle physics applications beyond a Higgs factory.

Speaker: John Farmer (Max Planck Institute for Physics)

16:00 Quasi-frozen spin concept to search for the electric dipole moment of the proton and deuteron

One of the possible proofs of CP violation beyond the Standard Model may be the discovery of permanent Electric Dipole Moments (EDM) of elementary particles. To search for the EDM of charged particles, the Frozen Spin (FS) concept was first proposed at BNL. The implementation of the latter involves the creation of a special storage ring in which the spin vector is preserved along the momentum and precesses due to the EDM only. In a magnetic storage ring initially not dedicated to measure the EDM, it is also possible to study the EDM by inserting electrostatic or E+B elements that compensate for the spin rotation in the bending magnets in a so-called Quasi-Frozen Spin (QFS) mode. Magneto-optical structures fulfilling the QFS condition can be used in application to study the proton and deuteron EDM and for axion search at the NICA accelerator complex. The main features of the implementation of the QFS concept are discussed, the method of measuring the EDM in the frequency domain, as well as the main spin dynamics properties of the lattice are covered.

Speaker: Aleksei Melnikov (Russian Academy of Sciences)

16:00 Recent advances in superconducting undulators at the Advanced Photon Source

The Advanced Photon Source (APS) continues developing novel SCUs, several of which have operated for a decade, delivering high-brightness, hard X-ray beams for scientific research. As part of the APS Upgrade, eight new NbTi SCUs were planned. While cryogenic and support systems were in place, challenges in scaling magnet lengths and reducing periods led to magnet failures and fabrication delays. The APS SCU team launched an R&D program to refine designs and materials, with two SCUs expected to be installed by late 2025 and six more to follow.
Before the APS Upgrade, a novel Nb₃Sn SCU deployed and operated successfully for three months, validating its predicted performance. Building on this, the APS SCU team is developing a 14 mm period Nb₃Sn SCU with cryogen-free, conduction-cooled magnets and a thin-wall vacuum chamber, enhancing the field and simplifying cryogenics. Looking further ahead, the team is exploring implementation of high temperature superconductors for lower period undulators (~10 mm) to achieve unprecedented field strengths. This presentation will provide an overview of the APS SCU program, the challenges addressed, and ongoing efforts to advance SCU technology.

Speaker: Ibrahim Kesgin (Argonne National Laboratory)

16:00 Revolution in generation of polarized electron beams: the world's first RF electron gun with GaAs photocathode

Polarized electron beams play critical role in fundamental physics research by providing additional observables and opening new channels of discoveries. T GaAs crystals illuminated by circular polarized IR lasers remain the best choice for generating polarized electrons. All current polarized sources are an electrostatic electron guns providing necessary extreme (XUV) vacuum conditions for survival of GaAs photo-emissivity. But they are limited in accelerating voltage and its gradient limiting both the quality and quantity of available beams. These are the reasons why accelerator community was and is attempting to extend this technology to the radio-frequency electron guns, which are capable of accelerating beams significantly higher accelerating gradients and total accelerating voltage. Unfortunately, all previous attempts of operating GaAs photocathodes in RF guns were unsuccessful. In this paper, we report on successful operation of GaAs photocathode in superconducting RF gun and describe all details of the gun, evolution of the GaAs quantum efficiency, and parameters generated electron beam.

Speaker: Vladimir Litvinenko (Stony Brook University)

16:00 RF heating and dark current at cryogenic temperature

Stable peak surface electric fields in excess of 200 MV/m are achievable at cryogenic temperatures in test cavities due to emprical reductions in RF breakdown rates. In order to fully capitalize on these effects, the complex physics at RF cavity interfaces in extreme conditions must be further understood from a basic physics perspective. Even before the onset of RF breakdown several precursor phenomena such as electron emission and RF pulse heating become relevant. To this end we present models for temperature dependent dark current and RF pulse heating focusing on temperatures between 40 and 80 K at peak fields between 100 and 200 MV/m. The models are semi-empirical and where relevant reference will be made to data collected at the CrYogenic Brightness Optimized Radio frequency Gun (CYBORG) at UCLA.

Speaker: Gerard Lawler (University of California, Los Angeles)

16:00 RF power margin for operation with fixed-target in the CERN SPS

The CERN Super Proton Synchrotron (SPS) Radio Frequency (RF) system was upgraded as part of the Large Hadron Collider Injector Upgrade (LIU) project, and now comprises six 200 MHz travelling wave structures, each fed by a separate RF power amplifier. While the upgrade was targeting the peak power for capture and acceleration of the beams for the High Luminosity LHC, it also brought an increase in the available average power for fixed-target beams. The additional power introduced margins which were first probed and exploited in 2024, when the SPS RF system had to be operated at majorly reduced power, during failures that blocked a single power amplifier or accelerating structure. Specific examples from the 2024 run are given, together with the mitigation measures. This contribution summarizes the efforts and results, highlighting in particular the improvements needed for the control of the RF voltage for easier switching to the degraded mode of operation and back, as well as the impact of the impedance of an undriven cavity.

Speaker: Giulia Papotti (European Organization for Nuclear Research)

16:00 S-parameters live measurement for the multiport RF components: applications to the circulator and the LIPAc RFQ cavity

In general, it is not easy to measure the drifting RF properties of a device during its operation. If the scatter matrix changes depending on the temperature, the vector network analyzer provides only a static or a starting point of the thermal development. In particular, it is impossible to fully characterize the component that has more than two ports only by the online measurement. So, in the model proposed, assuming that the heat source defined as the average dissipation is given by stored power in the device and the duty cycle, preliminary measurements for several average dissipations are performed. Analytical solutions are derived by using the preliminary and online measurement for the same average dissipation based on the input-output power pickups. As study case, the method is applied to the circulators and the RFQ of the Linear IFMIF Prototype Accelerator, for the three-port and eight-port device case respectively. The model, the results of experiments, and discussions will be summarized in this report.

Speaker: Kouki Hirosawa (National Institutes for Quantum Science and Technology)

16:00 Simulation of carbon ion beam charge exchange in a tandem accelerator

A tandem accelerator is a type of electrostatic accelerator that utilizes the high-voltage terminal twice to achieve higher ion energy. In this accelerator, a charge exchange cell is positioned between the low-energy and high-energy sections of the accelerating tube, converting the negative ion beam into a positive one. The charge exchange cell can be categorized into two types: gaseous charge exchange cells and carbon foil-based charge exchange cells. To enhance beam transfer efficiency in a tandem accelerator, the gaseous charge exchange cell is generally preferred. This paper presents a simulation of the charge exchange process for negative carbon ions using nitrogen gas. The conversion efficiency of negative carbon ions to positive ions is calculated for various nitrogen gas throughputs.

Speaker: Sara Zarei (Nuclear Science and Technology Research Institute)

16:00 Simulation of RF components for the ICONE pilot: RFQ, rebuncher, DTL cavities and amplifiers

CEA is committed to delivering a study for a warm linac in the frame of the ICONE project. It aims at accelerating an 80-mA beam of protons up to 25 MeV, with a 6% duty cycle. The LINAC consists of: a proton source with low-energy beam transport line, an RFQ, a medium-energy beam transport line, and a warm DTL. All these components must be tuned at 352.2 MHz, to reach the required output energy. This document presents the RF studies made by CEA and INFN on the main RF components, including the RFQ, the rebunchers, IH- and Alvarez DTL cavities and the RF amplifiers.

Speaker: Pierrick Hamel (Commissariat à l'Energie Atomique)

16:00 Simulations of ion bombardment in thermionic cathode RF guns

Thermionic cathodes are well known as a robust source of electrons for a wide range of accelerator applications. In the case of Barium Oxide cathodes the low work function that allows emission at modest temperatures is achieved through a surface coating. This coating can be damaged from both ion bombardment and, in the case of RF sources, electron bombardment. Lifetime models that predict the dynamics of these coatings are based on DC electron guns. Understanding the dynamics of ion bombardment in thermionic RF electron guns and under operational conditions is paramount to understanding cathode lifetime and optimizing performance. In this paper we simulate the generation of ions through impact ionization in the APS electron gun. We then compute the energy distribution of ions deposited on the cathode and effective ionization cross section as we vary operational conditions. These simulations are compared with analytical calculations based on first principles.

Speaker: Jonathan Edelen (RadiaSoft (United States))

16:00 Simulations study of transverse wakefields in a dielectric wakefield acceleration scheme

Novel acceleration schemes aim to address the need for higher acceleration gradients which enable to minimise the size and costs of particle accelerators. One of these novel accelerator schemes is the dielectric wakefield acceleration (DWA), where an electron bunch is accelerated by the longitudinal wakefields generated within a dielectric lined waveguide by a leading drive bunch with higher charge. The advantages of this novel acceleration method include high accelerating field strength, the simplicity of its structure and the stability of the wakefield generated which is synchronous with the electron bunch. However, the drive bunch propagation length, and hence the achievable energy gain, is limited by the effect of the transverse wakefields. These fields deflect the bunch towards the dielectric, leading to charge losses, a phenomenon commonly referred to as beam break-up (BBU) instability. This study uses simulations to investigate the transverse wakefields and their impact on the beam dynamics in a DWA scheme with drive and witness (main) bunches. The findings will be further explored experimentally at the CLARA facility in Daresbury Laboratory.

Speaker: Beatriz Higuera Gonzalez (Cockcroft Institute)

16:00 Standing wave dielectric disk accelerating structure design and high power test results

A Dielectric Disk Accelerator (DDA) is a metallic accelerating structure loaded with dielectric disks to increase coupling between cells and group velocity, while still maintaining a high shunt impedance. This is crucial for achieving high efficiency, high gradient acceleration in the short pulse acceleration regime. Recent research of these structures has produced traveling wave structures that are powered by very short (~9 ns), very high power (400 MW) RF pulses using two beam acceleration at the Argonne Wakefield Accelerator. In testing, these structures have withstood more than 320 MW of power and produced accelerating gradients of over 100 MV/m. A new standing wave DDA structure was fabricated and high power tested on the Nextef2 test stand at KEK. This experiment tested how the structure behaves on a more conventional, klystron power source. Simulation results of this structure show that at 50 MW of input power, the DDA produces a 457 MV/m gradient. It also has a large shunt impedance of 160 MΩm with an r/Q of 21.6 kΩm. High power testing concluded November 2024 with data processing ongoing. During testing a peak power of > 20 MW was reached and a pulse length of 200 ns.

Speaker: Sarah Weatherly (Illinois Institute of Technology)

16:00 Status of the 1st Article NbTi SCU for the Advanced Photon Source Upgrade

The 1st article NbTi SCU consists of two 1.5 m-long superconducting undulators (SCU) installed in a single cryostat that will occupy an entire straight section in the upgraded storage ring at the Advanced Photon Source. Installation is planned during the winter shutdown of 2025/2026. The initial design of the magnets proved to be difficult to successfully implement and a new design was pursued to resolve the issues that were identified. Manufacturing of the updated magnet design is scheduled to be completed in early 2025 after which the magnets will be tested in a vertical bath cryostat followed by installation into the production cryostat. A description of the magnet design modifications along with test results from the bath cryostat will be provided.

Speaker: Matthew Kasa (Argonne National Laboratory)

16:00 Status report on modification of a 5 MeV electron photo-gun for generating vortex electrons at JINR

At the Joint Institute for Nuclear Research (JINR), we use an RF photo-gun generating electrons via UV laser-driver and accelerating them up to 5 MeV to make a source of the so-called vortex electrons with a quantized orbital angular momentum projection onto the propagation axis. Such electron beams with a low current have previously been obtained only at electron microscopes with the highest kinetic energy of 300 keV. If successful, this gun would be the first such source in the MeV energy range in the world that could further be used, for instance, as a source for the 200-MeV electron linac at JINR. We discuss the needed steps to achieve this goal and report on the results already obtained. In particular, we have modified the laser driver and obtained twisted light beams in the deep ultraviolet wavelength range with different values of the topological charge. The vorticity of the photons is expected to be transferred to electrons via photoemission. We also discuss alternative schemes with a magnetized cathode, usually employed for angular-momentum dominated beams which are classical counterparts of the vortex particles.

Speaker: Dmitry Karlovets (ITMO University)

16:00 Study on 200 MeV separated drift tube linac in Korea Multi-purpose Accelerator Complex

Korea Multi-purpose Accelerator Complex (KOMAC) has been preparing 200 MeV energy upgrade. As a possible upgrade choice, separated drift tube linac (SDTL) type is considered in this study. From 2D analysis, optimum cell design deriving maximized effective shunt impedance and minimized Kilpatrick number is obtained. Then, final tank parameters considering stems, slug tuners, vacuum ports are determined under resonance frequency of 350 MHz. Based on that, 3D calculation is conducted to address electromagnetic and thermo-mechanical analysis. Electromagnetic mode and field flatness are analyzed by tuning slug tuners. In addition, appropriate cooling system is designed to minimize resonance frequency and electromagnetic structure variation.

Speaker: Sungbin Park (Korea Atomic Energy Research Institute)

16:00 Study on Ion Bunch Generation Using a Laser Plasma RF Ion Source

The development of high-intensity, high-quality ion sources is essential for advanced applications such as particle beam therapy and nuclear physics experiments. The aim of this study is to integrate the Laser Plasma RF Ion Source (LaPRIS), currently under development, into the cyclotron at the Research Centre for Nuclear Physics (RCNP) in order to accelerate ion bunches with high precision and intensity for advanced applications. LaPRIS can generate laser-plasma in an RF field at the laser focus spot and produce bunches at arbitrary timings. Previous research* has achieved a proton beam with a peak current of 1.2 mA and a bunch width of 5 ns. This allows the charge per bunch to be increased by a factor of 100 compared to conventional systems. This makes it possible to track the beam behavior for each bunch, which has potential applications in high-intensity cyclotron research. The injection into the cyclotron must be matched to the acceptance, so the emittance of the beam bunches is measured under different laser characteristics and target conditions to investigate the beam properties.

Speaker: Shotaro Matsui (Osaka University)

16:00 Study on the time changes of the proton beam passing current from the ion source to the RFQ at J-PARC LINAC

Currently, in the J-PARC linac, beam commissioning between the ion source and RFQ mainly involves adjusting the extraction voltage of the ion source and the two solenoid magnets in the Low Energy Beam Transport line (LEBT) installed between the ion source and the RFQ. These parameters are determined to maximize the measured beam current at the current monitor (SCT) downstream of the RFQ. Previously, the SCT used as a reference had measured the beam current by cutting out a part of the macro bunch. However, to further improve the beam quality, we adjusted LEBT parameters using the newly measured method, which is an integrated whole macro bunch signal. The optimum value obtained by the new method differed from the previous. Therefore, to investigate the cause, we saved all the beam current waveforms of the SCT for reference and compared the ion sources and LEBT parameters of each. As a result, the current of the beam that passed through the RFQ changed over time within the macro bunch for certain ion source and LEBT parameter settings. In this presentation, we will introduce the above study results and discuss the cause of the temporal changes in beam current.

Speaker: Kota Okabe (Japan Proton Accelerator Research Complex)

16:00 Suppression of bunch destruction under resonant excitation of the wakefield

Acceleration by the wakefield in the plasma can provide compact sources of relativistic electron beams of high brightness. Free electron lasers and particle colliders, using plasma wakefield accelerators, require high quality bunches with predictable profile. Previous studies showed that the resonant sequence of electron bunches appears to be unstable due to the destruction of the bunches. In this paper we discuss the mechanism of this destruction due to the focusing field phase shift which appears during this time evolution. We numerically and analytically showed the possible way of suppressing this instability, shifting all bunches on some distance.

Speaker: Ilia Demydenko (V. N. Karazin Kharkiv National University)

16:00 Synthesis of efficient ordered sodium potassium antimonide photocathodes via molecular beam epitaxy

Alkali antimonide photocathodes exhibit high efficacy as photoemissive materials in electron sources. This proceeding explores the fabrication of thin, ordered films of sodium potassium antimonide via molecular-beam epitaxy (MBE) at the PHotocathode Epitaxy Beam Experiments (PHOEBE) laboratory at Cornell University. Utilizing a sequential deposition technique, the photocathodes are characterized in terms of both quantum efficiency (QE) and crystal structure with the goal of reducing the chemical and physical roughness. A spectral response from 400 to 700 nm demonstrates oscillations resulting from optical interference within the (SiN) substrate. Reflection high-energy electron diffraction (RHEED) patterns confirmed the successful growth of ordered crystal structures for the first time in a sodium potassium antimonide photocathode. Additionally, we investigated the photocathodes' sensitivity to oxidation, revealing their relative robustness compared to CsSb or KSb photocathodes. Notably, the incorporation of higher partial pressures of oxygen during growth improved QE and extended the operational lifetime of the photocathodes.

Speaker: Abigail Flint (Cornell University (CLASSE))

16:00 Technologies to sustain FRIB establishment and power ramp up

FRIB is the first linac to deploy a large number of half-wave-resonators (220 HWRs) and the first heavy ion linac to operate at 2 K. Such key technology has enabled FRIB to operate as the world’s highest energy continuous-wave hadron linac and highest-energy heavy ion linac delivering world’s highest uranium beam power (>10 kW) on target. The key technological experience may be shared with our society.
Key technologies that have sustained FRIB facility establishment and beam power ramp up include large-scale superconducting RF, SC magnets, liquid metal charge stripping, and high power targetry. This talk provides a summary of the technological development key to FRIB’s successful project completion and power ramp up to world’s frontier of high power heavy ion facilities.

Speaker: Ting Xu (Facility for Rare Isotope Beams)

16:00 The application of laser-irradiated pyroelectric crystals in neutron generators

Pyroelectric neutron generators have been one of the research hotspots in the field of neutron generation due to their advantages of compact structure and controllable intensity. A novel laser pyroelectric neutron generator was proposed by utilizing 1064nm wavelength pulsed laser irradiation on LiTaO3-Mo-TiDx for simultaneous heating and ionization. The laser irradiation on the pyroelectric crystal to generate high voltage potential, then focusing the laser to ionize TiDx to produce deuterium ions. Under the influence of an electric field, these deuterium ions bombard the surrounding titanium deuteride annular target to induce deuterium-deuterium nuclear reactions for neutron production. Experimental comparisons of crystal temperature change rates and surface temperature distributions under the action of pulsed laser and continuous laser are conducted. Finally, combined with COMSOL simulation results, the correlation between temperature changes and the maximum potential and acceleration gap electric field distribution is established. This study explores the main influencing factors of the maximum potential and electric field distribution in laser pyroelectric neutron generators.

Speaker: Zhen Yang (Sun Yat-sen University)

16:00 The SPARTA project: toward a demonstrator facility for multistage plasma acceleration

Plasma acceleration is a rapidly maturing technology, but is not yet ready for large-scale applications such as linear colliders. The SPARTA project aims to develop a near-term, medium-scale plasma-accelerator facility to enable new experiments in strong-field quantum electrodynamics (SFQED)—an application that requires solving two of the most important remaining challenges in plasma acceleration: reaching high energy by using multiple accelerating stages; and achieving high beam stability. We report on progress toward the three main objectives: demonstrating a nonlinear plasma lens for achromatic beam transport between stages; developing self-stabilization and instability suppression mechanisms; and developing a conceptual design for a multistage SFQED facility.

Speaker: Pierre Drobniak (University of Oslo)

16:00 Theoretical models for CsTe thin film semiconductor photocathodes at high electromagnetic fields

Understanding performance and limitation of CsTe photocathodes under high field gradients in a radio-frequency gun requires adequate theoretical models for material properties, photoemission and surface morphology. We are developing a suite of models based on Density Functional Theory (DFT), moment and Monte-Carlo (MC) photoemission models, and meso-scale material surface model informed by DFT and Molecular Dynamic (MD) simulations. Our DFT calculations provide detailed structural, elastic, electronic, optical, and transport properties of CsTe for photoemission applications. Temperature, density of states, and thin film optical effects have recently been incorporated in a moment-based photoemission model, while the high field effects for electron transport and emission are being modeled in the MC model. Our meso-scale surface model addresses surface morphology under high field stress and surface heating. Machine-learning technique has also been used to enhance the DFT and MD calculations for CsTe. This poster will present an overview of these theoretical models and their results with applications to the LANL CARIE project and other relevant experiments.

Speaker: Evgenya Simakov (Los Alamos National Laboratory)

16:00 Tomographic reconstruction and comparison with emittance data in the RAON

Tomographic reconstruction of beam distribution using four wirescanners has been carried out and a comparison is made with the Allison scanner data at the RAON. Tomography technique which is valid under strong space charge effect is applied in the LEBT, MEBT and SCL sections. Also comparison is made with method to get beam parameters using wirescanner rms beam sizes

Speaker: Dong-O Jeon (Institute for Basic Science)

16:00 Transverse stability of multiple trailing bunches in filament-regime plasma wakefield acceleration

Plasma wakefield acceleration in the filament regime can provide wakefields suitable for high-gradient, high-quality positron acceleration while maintaining stability. However, the energy that can be extracted by the positrons is limited. Recent works have proposed accelerating a supplementary electron recovery bunch along with the positron bunch to extract more energy from the wake and improve the overall transfer efficiency during acceleration. However, it is unclear if such energy recovery schemes are stable when subject to misalignment. In this work, we employ quasi-static particle-in-cell simulations to study the transverse stability of configurations involving three bunches.

Speaker: Rafael Yrjosmiel Legaspi (Mapúa University)

16:00 Transverse tolerances in the plasma-wakefield acceleration blow-out regime

We report on recent progress in transverse instabilities and transverse tolerances for plasma-wakefield accelerators in the blow-out regime. In this regime, the transverse fields provide both strong focusing and strong deflection via transverse wakefields. The deflection effect of the wakefields on the main beam leads to limitations on the acceleration efficiency, if not mitigated. Based on comprehensive particle-in-cell simulations we summarize recent findings of the instability--efficiency relation for the blow-out regime. Ion motion and energy spread may mitigate the instability; with linac start-to-end simulations, using the recently developed ABEL framework, we demonstrate that the instability and emittance growth may be sufficiently mitigated for the colliding beams in the HALHF concept. Independent of wakefield effects, the strong focusing fields lead to very tight tolerances for the drive-beam jitter. We quantify these tolerances, using examples from HALHF start-to-end simulations. We show that the tolerances are greatly loosened by applying external magnetic fields to guide the drive-beam propagation in the plasma.

Speaker: Erik Adli (University of Oslo)

16:00 TURBO – Enabling fast energy switching for hadron therapy with constant magnetic fields

The energy layer switching time is a limiting factor for hadron therapy, precluding fast beam delivery and reducing treatment efficacy. For rapid energy switching the beam delivery system must be achromatic with zero dispersion over a large energy range. At the University of Melbourne, the TURBO project will utilise Fixed Field Accelerator techniques to demonstrate transport of a ±42% momentum spread beam around a 30° bend, with constant magnetic fields to eliminate the energy switching bottleneck. This will be demonstrated with an electrostatic Pelletron accelerator. A fast-switching energy degrader with thin diamond films has been designed to quickly change proton beam energies in the range 0.5-3.0MeV, covering the full clinical range when scaled up. A new design technique using nonlinear magnetic fields for energy-dependent focusing has been developed to minimise delivered beam variations. A novel method has been found to produce nonlinear permanent magnet arrays without custom magnets, enabling fast prototyping and reuse of magnets. With these innovations, the TURBO project will demonstrate rapid energy switching for hadron therapy to enable improvements in patient outcomes.

Speaker: Adam Steinberg (The University of Melbourne)

16:00 Update of the tune ripple canceller system for slow extraction operation in the J-PARC MR

In the slow extraction operation of the J-PARC Main Ring (MR), ensuring the uniformity of the extracted beam's time structure (“spill structure”) is crucial. One primary factor distorting the spill structure is the random fluctuation of the horizontal tune caused by current ripples in the main magnet power supplies. To address this issue, a system called the "tune ripple canceller" has been developed. This system calculates correction values for the horizontal betatron tune based on current ripples and controls the spill structure using fast-responding quadrupole magnets. In 2021, proof-of-principle beam experiments demonstrated its effectiveness in improving the spill structure. Subsequently, as part of the MR's power upgrade plan, the main magnet power supply system was upgraded by 2022. During this upgrade, the current measurement system was reconfigured, and the power spectrum of the current ripples was altered. As a result, it is now urgent to update the hardware and software of the tune ripple canceller system to align with these changes. This paper highlights updates, addresses challenges, and explores strategies to further enhance spill structure control in the MR.

Speaker: Takashi Asami (Japan Proton Accelerator Research Complex)

16:00 Wafer-compatible photocathode plug design for high gradient RF photoinjector

Single crystal alkali antimonide photocathodes have been shown to produce brighter beams than their polycrystalline counterparts. These single crystal semiconductors require a lattice matched substrate to be grown, but current INFN plugs lack the capability for this growth. To relieve this issue, we modified the INFN plug to hold a disk 1cm in diameter. This allows for studies of a wide range of advanced photocathodes and geometries on arbitrary substrates in high gradient photoinjectors. We show the modified design, analysis of the local field at the cathode and cavity detuning, and demonstrate the principle with a 1cm Yttrium disk.

Speaker: David Garcia (University of California, Los Angeles)

16:00 Wakefield studies of the taper section of the elliptical in-vacuum undulator - IVUE32

The elliptical in-vacuum undulator (IVU) IVUE32 is being developed at Helmholtz-Zentrum Berlin (HZB). The APPLE-II design allows for not only gap changes but also longitudinal shift movements, putting additional design challenges on the tapers at the entrance and exit of the undulator. The chosen design philosophy separates the gap and shift movement compensation into two assemblies respectively. This approach allows for a solid foil taper as gap movement compensation, which is proven in previously commissioned planar IVUs e.g. CPMU17 at HZB. The shift movement compensation, which requires a slit foil, can be kept parallel. The proximity of this complex structure to the electron beam makes the device susceptible to wakefield effects which can influence beam stability. Investigating and understanding these effects is vital for accelerator operation. The taper design will be presented alongside wakefield simulations and model measurements.

Speaker: Stefan Grimmer (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 Wakefields in an elliptical cavity and alternating-structure stability analyses

We present the analytical solution for the transverse and longitudinal wakefields in a perfectly conducting elliptical cavity following from a conformal mapping formalism. These closed-form results are corroborated by numerical calculations. Simple representations of the dipole and quadrupole modes as a function of the cavity dimensions then precipitate, permitting the analyses of the beam tail’s emittance preservation and BNS damping in an alternating structure. We then consider general forms for the dipole and quadrupole components as functions of the longitudinal coordinate and determine what perturbations to such a structure may improve stability.

Speaker: Joshua Mann (University of California, Los Angeles)

16:00 Wien filter method for the "Quasi-frozen" spin lattice

To study the electric dipole moment of light nuclei, it is necessary to maintain the direction of the spin along the particle's motion along the ring. The first obvious solution to this problem is to use elements with an electric field that rotates the spin in the direction opposite to the spin rotation in a magnetic field. The most successful solution in this case is the Wien filter, which ensures spin rotation while maintaining the co-direction of the spin and momentum. In this case, the ring structure consists of arcs with bending magnets and straight sections on which Wien filters with crossed electric and magnetic fields are installed. The paper considers various versions of a magneto-optical structure that implements the "Quasi-frozen" spin method for studying the electric dipole moment of deuterons and protons. This approach can be used in developing an upgraded Nuclotron structure.

Speaker: Aleksei Melnikov (Russian Academy of Sciences)

18:30 → 20:00 Productive Research Environment Session

Conveners: Mika Masuzawa (High Energy Accelerator Research Organization), Yoichi Sato (Japan Proton Accelerator Research Complex)

18:30 PRE1

Speaker: Angeles Faus-Golfe (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

18:50 PRE2

Speaker: Somjai Chunjarean (Synchrotron Light Research Institute)

19:10 PRE3

Speaker: Mika Masuzawa (High Energy Accelerator Research Organization)

Wednesday 4 June

09:00 → 09:30 WEXD:Accelerator Technology and Sustainability (Invited)

Convener: Ralf Gebel (GSI Helmholtz Centre for Heavy Ion Research)

09:00 Experimental demonstration of particle acceleration with normal conducting accelerating structure at cryogenic temperature

In this paper, we present an experimental demonstration of the high-gradient operation of an X-band, 11.424 GHz, 20-cells linear accelerator (linac) operating at a liquid nitrogen temperature of 77 K. The tested linac was previously processed and tested at room temperature. Low-temperature operation increases the yield strength of the accelerator material and reduces surface resistance, hence a great reduction in cyclic fatigue could be achieved resulting in a large reduction in breakdown rates compared to room-temperature operation. Furthermore, temperature reduction increases the intrinsic quality factor of the accelerating cavities, and consequently, the shunt impedance leading to increased rf-to-beam efficiency and beam loading capabilities. We verified the enhanced accelerating parameters of the tested accelerator at cryogenic temperature using different measurements including electron beam acceleration up to a gradient of 150 MV/m, corresponding to a peak surface electric field of 375bMV/m. We also measured the breakdown rates in the tested structure showing a reduction of 2 orders of magnitude compared to their values at room temperature for the same accelerating gradient.

Speaker: Sami Tantawi (Arizona State University)

09:00 → 09:30 WEXN:Beam Instrumentation and Controls, Feedback and Operational Aspects (Invited)

Convener: Thapakron Pulampong (Synchrotron Light Research Institute)

09:00 Upgrade of KEK electron/positron injector LINAC using pulsed magnets and machine learning

The KEK injector linac injects high-charge electron and positron beams into the high-energy-ring and low-energy-ring of SuperKEKB respectively. The linac also injects electron beams to the two light source rings, PF ring and PF-AR. We operate simultaneous top-up injections into the four rings by using many pulsed magnets. We have been upgrading the linac to attain the higher-quality beam injections for the SuperKEKB rings. In the summer of 2023, large-aperture quadrupole pulsed magnets have been newly installed upstream of the linac and driven by large-current pulse power supplies at markedly high electric efficiency. These new magnets bring the pulse-by-pulse optics changing to provide the high-quality beams. In order to cope with the complex beam injections to the four rings, we have introduced the automatic adjustment system by using machine-learning. The system surpasses human skill in beam adjustment and has resulted in significant increases in the amount of beam charge and beam transmission. We will report on the results of these upgrades.

Speakers: Masanori Satoh (High Energy Accelerator Research Organization), Takuya Natsui (High Energy Accelerator Research Organization), Dr Yuichi Okayasu (High Energy Accelerator Research Organization)

09:30 → 10:30 WEAD:Accelerator Technology and Sustainability (Contributed): MC7

Convener: Ralf Gebel (GSI Helmholtz Centre for Heavy Ion Research)

09:30 20 years of CESR-B cavity operation at the CLS

The Canadian Light Source (CLS), a 3^rd generation synchrotron light source, has operated the CESR-B type superconducting radio frequency cavity since 2005. We report on 20 years of operating experience of the facility with this type of accelerating cavity.

Speaker: Frédéric Le Pimpec (Canadian Light Source (Canada))

09:50 High power RF testing of high temperature superconductors

Superconducting materials such as niobium have been extremely useful for accelerator technology but require low temperature operation ~2 K. The development of high temperature superconductors (HTS) is promising due to their operating temperatures being closer to that of liquid nitrogen ~77 K. This work aims to determine the high-power RF performance of these materials at X-band (11.424 GHz). We have tested several types of rare earth barium copper oxide (REBCO) materials, such as films deposited by electron-beam physical vapor deposition, coated conductors soldered to a copper substrate, and solid pucks formed from powder. RF testing was done via a hemispherical TE mode cavity that maximizes the magnetic field and minimizes the electric field on a 2-inch sample region. We will report on surface resistance vs temperature measurements at low and high power,as well as RF testing of a pulse compression cavity lined with REBCO coated conductors.

Speaker: Ankur Dhar (SLAC National Accelerator Laboratory)

10:10 Further high power tests of the additive manufacturing IH-type cavity

Additive manufacturing (AM) has become a powerful tool for rapid prototyping and manufacturing of complex geometries. A 433 MHz IH-DTL cavity has been constructed as a proof of concept for direct additive manufacturing of linac components. In this design, the internal drift tube structure has been produced from pure copper using AM. We present the most recent results from high-power tests with the AM IH-type structure, including additional tests with improved surfaces to reduce field emission during operation.

Speaker: Dr Hendrik Hähnel (Goethe University Frankfurt)

09:30 → 10:30 WEAN:Beam Instrumentation and Controls, Feedback and Operational Aspects (Contrubited)

Convener: Thapakron Pulampong (Synchrotron Light Research Institute)

09:30 Measurement techniques using the electron beam profile scanner at the Fermilab Main Injector

This work presents techniques for non-invasive transverse profile measurements of high-intensity proton beams using an Electron Beam Profile Scanner (EBPS). The EBPS utilizes low-energy electrons as a probe to analyze the transverse size of proton beams, allowing for potential analysis on a single-bunch basis. Recent upgrades to the Fermilab Main Injector have enhanced beam power on target to 1 MW, with future developments targeting 2 MW. The higher beam power has increased the demand for non-invasive diagnostics, as invasive methods can disrupt operations.
The techniques presented include 1) the slow scan technique, which serves as a proof of concept for the probe beam, 2) the one-shot scan technique for measuring horizontal beam profiles, and 3) the raster scan technique for analyzing horizontal beam profiles as a function of the longitudinal distribution of the beam. The profiles obtained will be crucial for studying and understanding instabilities in high-power, high-intensity proton beams. This will contribute to optimizing the operation of high-power proton accelerators by minimizing beam loss, activation, and damage to both the diagnostics and the accelerator components.

Speaker: Matilda Mwaniki (Illinois Institute of Technology)

09:50 Data-driven hysteresis compensation in the CERN SPS main magnets

Magnetic hysteresis and eddy current decay continue to challenge beam quality and operational consistency in multi-cycling machines like the Super Proton Synchrotron (SPS) at CERN. Building on our previous work, this paper presents improvements in the data-driven approach for magnetic field modelling to enhance the reproducibility of SPS dipole and quadrupole fields and thus maintain stable beam parameters across all operational cycles. The method is based on feed-forward correction using magnetic field forecasting with machine learning. It now includes additional operational experience and demonstrates that the field error compensation can reliably be used in operation. This contribution proves that hysteresis compensation can be achieved without a feedback system based on expensive installations with online field measurements in reference magnets. The performance improvements achieved by eliminating the need for manual adjustments and reducing time- and energy-consuming accelerator pre-cycles are presented. The paper also sets the stage for future application in higher-order magnets, like sextupoles and octupoles, as well as on other CERN synchrotrons.

Speaker: Anton Lu (TU Wien, European Organization for Nuclear Research)

10:10 Supersonic gas curtain-based in-vivo transverse beam profile monitoring for medical accelerators

To ensure patient safety, treatment effectiveness, and facility efficiency, each ion beam therapy facility requires a complete online characterization of the charged particle beam. Existing dosimetry methods are either limited in the information they provide or invasive to the beam, highlighting the need for new in-vivo dosimetry solutions. Since 2015, the QUASAR Group at the Cockcroft Institute, UK has been developing non-invasive beam monitors for medical accelerators. Accurate monitoring of the transverse beam profile is the first step toward achieving in-vivo dosimetry. The monitor, under development, utilizes a supersonic gas curtain that interacts with the charged particle beam, using the resulting impact ionization to measure the transverse beam profile. A prototype monitor was successfully tested for proof-of-concept measurements at the Dalton Cumbrian Facility’s pelletron accelerator (UK). Measurements were conducted using various beam parameters with both proton and carbon ion beams. This contribution presents the monitor's design and operating principle, experimental results from the measurements, and additional planned improvements aimed at achieving in-vivo dosimetry.

Speaker: Dr Narender Kumar (Cockcroft Institute)

10:30 → 11:00 Coffee Break

11:00 → 11:30 WEYD:Accelerator Technology and Sustainability (Invited)

Convener: Peter McIntosh (Science and Technology Facilities Council)

11:00 Assessing and increasing the sustainability of future accelerator based facilities

The long term sustainability of future accelerators is now a crucial problem for our community. Many groups and collaborations are actively working in this area (e.g. European projects included IFAST and iSAS, RUEDI (STFC) has recently published a case study for the project lifecycle, Centre of Excellence in Sustainable Accelerators is now being vigorously pursued in the UK with CERN backing, European LDG working group, etc). This talk will review the wider community efforts and highlight where good progress is being made and where future efforts are planned or required.

Speaker: Ben Shepherd (Science and Technology Facilities Council)

11:00 → 11:30 WEYN:Beam Dynamics and EM Fields (Invited)

Convener: Nicolas Delerue (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

11:00 Ultrafast visualization of quasi-three-dimensional electric field of relativistic electron beam

EM (electromagnetic) field around a relativistically ac-celerated charged particle is known to be squeezed longi-tudinally. This behavior is called the Lorentz contraction, and no inconsistent phenomena have been found. How-ever, an experiment has not directly confirmed the Lo-rentz contraction of the EM field. The first direct observa-tion of the Lorentz contraction of the EM field was recent-ly performed using an electron linac at the University of Osaka[*]. The electric (Coulomb) field around a sub-picosecond electron beam with an energy of 35 MeV was measured by an electro-optic (EO) sampling method. A single-shot electric field measurement system was devel-oped using EO sampling and an echelon mirror. A modu-lated laser light due to the Pockels effect was decoded into a spatio-temporal image of the electric field, and the Lo-rentz contraction was directly confirmed. This ultrafast measurement technique can help longitudinal diagnostics of a charged particle beam. This presentation will report ultrafast visualization of quasi-three-dimensional (trans-verse and longitudinal) electric fields of a relativistic elec-tron beam and their evolutions.

Speaker: Dr Koichi Kan (National Institutes for Quantum Science and Technology)

11:30 → 12:30 WEBD:Accelerator Technology and Sustainability (Contributed)

Convener: Peter McIntosh (Science and Technology Facilities Council)

11:30 Cryogenic eficiency and sustainability aspects for particle accelerators & detectors

Cryogenics is a key enabling technology for present and future particle accelerators and detectors, providing the conditions required for the operation of superconducting magnets, superconducting RF cavities, vacuum systems, and particle detection devices. However, extracting heat at very low temperatures requires large amounts of energy, often representing a major share of the total energy demands of the facilities. This article presents the main factors driving energy consumption, the status of the technology for a large spectrum of temperatures, and possible developments for improving the efficiency of cryogenic systems. It discusses the impact of cryogenic cooling configurations and the potential of new superconducting materials towards improved sustainability of future accelerators and particle detectors.

Speaker: Antonio Perin (European Organization for Nuclear Research)

11:50 Active 3rd harmonic RF system for ALBA

ALBA is a 3rd generation synchrotron light source located in Barcelona, Spain. The circumference is 268.8 meters and electrons are stored at 3 GeV. In the framework of the upgrade towards the 4th generation light source ALBA II, an active 3rd harmonic RF system at 1.5 GHz is foreseen to increase the Touschek lifetime component. The system will be installed and available for operation in the current machine, which will allow to gather experience before the upgrade. Four normal conducting HOM damped harmonic cavities will be placed in the storage ring, each of it including a complete WR650 waveguide system with circulator and load, a 20 kW high power SSPA amplifier and a Low Level RF control system. We are presenting in this contribution the complete design of the active harmonic RF system for ALBA and the expected performance during operation.

Speaker: Francis Perez (ALBA Synchrotron (Spain))

12:10 Integrating permanent magnets and electromagnets: a hybrid dipole magnet design

In this study, we designed a hybrid dipole magnet that integrates both permanent magnet and electromagnet technologies. The primary magnetic field is generated by the permanent magnets, while the coils enable fine-tuning of the field. The design carefully considers the placement of the permanent magnets and coils to optimize performance. Additionally, an outer plate mechanism is incorporated for coarse magnetic field adjustments, and a NiFe compensator is employed to mitigate the effects of temperature variations on the magnetic field. Given the challenges and risks associated with assembling strong magnets, we also developed a detailed assembly procedure and a set of specialized fixtures to ensure safe and efficient assembly. The integration of permanent and electromagnetic technologies in this hybrid design provides a robust and adaptable solution, paving the way for innovative applications in advanced accelerator technologies.

Speaker: Yang-Yang Hsu (National Synchrotron Radiation Research Center)

11:30 → 12:30 WEBN:Beam Dynamics and EM Fields (Contributed)

Convener: Nicolas Delerue (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

11:30 Empowering a broad and diverse community in beam dynamics simulations with Xsuite

Xsuite is a Python toolkit for modelling and simulation of particle accelerators, which has been developed at CERN together with collaborators from other institutes over the past four years. The code has reached a mature development stage and has become the workhorse for several studies and applications, allowing the gradual replacement of legacy tools like Sixtrack, COMBI, PyHEADTAIL. This contribution provides an overview of the code capabilities and illustrates examples in different areas of accelerator science, including low-energy hadron rings for medical applications, high-intensity hadron accelerators, synchrotron light sources, high-energy hadron and lepton colliders.

Speaker: Szymon Lopaciuk (European Organization for Nuclear Research)

11:50 A module for fast auto differentiable simulations

The auto differentiable simulation is a type of simulation that outputs of the simulation contain not only the simulation result itself, but also its derivatives with respect to many input parameters. It provides an efficient method to study the sensitivity of the simulation result with respect to the input parameters and can be used in some gradient based optimization methods for fast parameter design optimization. In this paper, we report on the development of a fast auto differentiation module that can be used in many simulation codes.

Speaker: Ji Qiang (Lawrence Berkeley National Laboratory)

12:10 Off-resonance scheme for highly coupled lattice design in the diffraction-limited light sources

Round beam operation offers significant benefits for synchrotron radiation experiments and reduces intra-beam scattering effects in diffraction-limited light sources. This paper proposes a method for round beam generation based on global skew quadrupole settings and the application of the Non-Dominated Sorting Genetic Algorithm (NSGA). Two coupling schemes, large emittance coupling via betatron coupling and vertical dispersion, are explored in a candidate lattice for the Shanghai Synchrotron Radiation Facility upgrade. We investigate the impact of lattice imperfections and beam optics distortions on emittance variations and beam dynamics. The results demonstrate precise control of beam coupling (from 10% to 100%) under low optics distortion, with full coupling generation and robustness achieved by adjusting skew quadrupoles in dispersion-free sections. Additionally, the method leads to a 2-2.5x increase in Touschek lifetime.

Speaker: Yihao Gong (Shanghai Synchrotron Radiation Facility)

12:30 → 14:00 Lunch

14:00 → 15:00 WEUD Industrial Session

Convener: Yoichi Sato (Japan Proton Accelerator Research Complex)

14:00 Applications of High Impedance Magnetic Alloy

Speaker: Chihiro Ohmori (Japan Proton Accelerator Research Complex)

14:25 Student Viewpoints on Career Pathways

Speaker: John Salvesen (European Organization for Nuclear Research)

14:40 Building Taiwan’s First Heavy Ion Therapy Center: Lessons from Partnership with Ruentex, Hitachi, and NSRRC

To introduce the Heavy Ion Therapy Center of Taipei VGH and share the experience of its construction, installation and commissioning.

Speaker: Ching-Sheng Liu (Kaohsiung Veterans General Hospital)

14:00 → 15:00 WEZN:Photon Sources and Electron Accelerators (Invited)

Convener: Adriana Wawrzyniak (SOLARIS National Synchrotron Radiation Centre)

14:00 Cascaded hard X-ray self-seeded free-electron laser at megahertz repetition rate

High-resolution X-ray spectroscopy in the sub-nanosecond to femtosecond time range requires ultrashort X-ray pulses and a spectral X-ray flux considerably larger than that presently available. X-ray free-electron laser (XFEL) radiation from hard X-ray self-seeding (HXRSS) setups has been demonstrated in the past and offers the necessary peak flux properties. So far, these systems could not provide high repetition rates enabling a high average flux. We report the results for a cascaded HXRSS system installed at the European XFEL, currently the only operating high-repetition-rate hard X-ray XFEL facility worldwide. A high repetition rate, combined with HXRSS, allows the generation of millijoule-level pulses in the photon energy range of 6–14 keV with a bandwidth of around 1 eV (corresponding to about 1 mJ eV–1 peak spectral density) at the rate of ten trains per second, each train including hundreds of pulses arriving at a megahertz repetition rate. At 2.25 MHz repetition rate and photon energies in the 6–7 keV range, we observed and characterized the heat-load effects on the HXRSS crystals, substantially altering the spectra of subsequent X-ray pulses. We demonstrated that our cascaded self-seeding scheme reduces this detrimental effect to below the detection level. This opens up exciting new possibilities in a wide range of scientific fields employing ultrafast X-ray spectroscopy, scattering and imaging techniques.

Speaker: Shan Liu (Deutsches Elektronen-Synchrotron DESY)

14:30 LCLS-II commissioning and operation with high-repetition-rate CW FELs

LCLS-II first stage commissioning is completed in the summer of 2023, with demonstration of 93 kHz electron beam and 1 kHz FELs using the superconducting CW linac. Operation-based electron beam and FEL commissioning has been continued with the goal of ramping up beam rate, improving the FEL performance, and developing advanced FEL operation modes. We started 33 kHz x-ray FELs to user experiments from 2025. The latest machine performance, commissioning challenges, and next-step plan will be discussed in this paper

Speaker: Yuantao Ding (SLAC National Accelerator Laboratory)

15:00 → 15:30 WEZD:Colliders and Related Accelerators (Invited)

Convener: Yoichi Sato (Japan Proton Accelerator Research Complex)

15:00 Design initiatives for a 10 TeV pCM wakefield collider

The recent P5 Report calls for a 10 TeV parton center-of-mass (pCM) collider, for which advanced wakefield accelerators are a candidate technology. Design studies are being developed including particle sources, damping rings, and linacs based on plasma and structure-based wakefield accelerators. Compact Beam Delivery Systems may be possible using plasma lenses, requiring understanding of their impact on the design of the Machine-Detector Interface, and optimization of detectors for 10 TeV e+e- and γγ collisions. The results of the design study will define the necessary technology demonstrations to be performed. There are synergies between the design of a 10 TeV linear collider and Higgs Factory linear colliders. This study is hence developing tools and innovations that can be broadly useful to the collider community, and interaction among efforts is important.

Speaker: Stewart Boogert (Cockcroft Institute)

15:00 → 15:40 WECN:Photon Sources and Electron Accelerators (Contributed)

Convener: Adriana Wawrzyniak (SOLARIS National Synchrotron Radiation Centre)

15:00 SLS 2.0 storage ring commissioning

The SLS consists of a 100MeV linac, a 2.7GeV booster synchrotron with 9nm horizontal emittance and the storage ring (SR). The old 12-TBA SR with 5nm horizontal emittance operating at 2.4GeV was turned off in 09/2023 after 22 years of successful user operation. In course of the SLS 2.0 upgrade project the 288m circumference SR has been replaced by a 2.7GeV 12-fold 7-bend achromat lattice with a considerably reduced horizontal emittance of 150pm, while keeping the injector complex mostly unchanged. After recommissioning of the injector chain at the end of 2024 SR commissioning starts in January 2025 with some challenges ahead. A reverse bend design has been implemented to achieve the lowest possible emittance with the given small footprint of the SR leading to a very dense magnet arrangement. All bending and combined function magnets which largely determine the novel optics are permanent magnets which will guide the beam through NEG coated vacuum tubes with an aperture of only 18mm. Due to excellent beam diagnostics and optics adjustment capabilities combined with an advanced remote girder alignment system we expect to achieve the performance goals of the storage ring by mid 2025.

Speaker: Michael Böge (Paul Scherrer Institute)

15:20 First beam commissioning of the HZB SRF photoelectron gun

The versatile 1.3 GHz superconducting radio-frequency (SRF) gun at HZB succesfully generated first photoemission beam from a high quantum efficiency (QE) multi-alkali photocathode. This demonstrates worldwide first beam operation of a SRF gun at high repetition rate and with a robust multi-alkali Na-based photoemissionn source. The setup of the test and all sub-systems is described. The latest results of SRF commissioning, cavity performance, photocathode QE measurements and beam parameter exploration campaigns is presented in the paper.

Speaker: Thorsten Kamps (Helmholtz-Zentrum Berlin für Materialien und Energie)

15:30 → 16:00 WE1D:Novel Particle Sources and Acceleration Techniques (Invited)

Convener: Yoichi Sato (Japan Proton Accelerator Research Complex)

15:30 Enhanced proton and neutron production using the ultra-short (24 fs) and high-power (2 PW) Apollon laser facility

We will review interesting advances we have been able to perform in the domain of laser-driven generation of proton and neutron beams, using the new ultra-high power Apollon laser facility (France). Thanks to the ability to tailor the ultra-short timescales of the temporal pedestal of the laser pulse, we have notably been able to accelerate protons in a “lighthouse” fashion, whereby the highest-energy component of the beam is emitted in a narrow cone, well separated from the lower-energy components. As a result, the spectrum of the output protons can be easily adjusted by collecting them along a specific direction, therefore removing a major roadblock of these beams, which are otherwise spectrally broadband. This approach offers the advantages of leveraging a robust sheath acceleration process in standard micron-thick targets and being optically controllable. We have also demonstrated that, when enhancing the temporal contrast by using plasma mirrors, we could enhance the laser-to-target coupling and the proton energy, as well as reduce the angular divergence of the proton beams. Last, we will review the high flux neutrons that can be produced using these beams when using (p,n) reactions in Li. The measured high fluxes that can be obtained using Apollon open perspectives for getting insight into nucleosynthesis of elements.

Speaker: Julien Fuchs (Centre National de la Recherche Scientifique, Laboratoire pour l'utilisation des lasers intenses)

15:40 → 16:00 WEFN:Beam Instrumentation and Controls, Feedback and Operational Aspects (Contributed)

Convener: Adriana Wawrzyniak (SOLARIS National Synchrotron Radiation Centre)

15:40 Experimental demonstration of transient-beam-loading compensation using new digital LLRF system at the Photon Factory storage ring

In ultra-low-emittance synchrotron light sources, the bunch-lengthening technique is useful to mitigate harmful effects due to the intrabeam scattering. The perfomacne of the bunch lengthening can be degraded by the transient beam loading (TBL) effect induced in the cavities. To mitigate the TBL effect, we proposed a TBL compensation technique using a wide-band longitudinal kicker cavity. In this presentation, we report the result of the experimental demonstration of the TBL compensation performed at the KEK PF 2.5 GeV ring. In this experiment, the fill pattern of the electron bunches were customized to enlarge the phase variation of electron bunches induced by the TBL effect. The fundamental cavities and newly developed digital low-level RF (DLLRF) system were used for the experiment. The DLLRF enables the TBL compensation by an arbitrary feedforward pattern of the cavity voltage modulation that is synchronized with the revolution frequency. Although the bandwidth of the fundamental cavity is limited, the variation of the cavity voltage and bunch phase induced by the TBL effect was reasonably mitigated by applying sinusoidal wave modulation of the cavity voltage.

Speaker: Daichi Naito (High Energy Accelerator Research Organization)

16:00 → 18:00 Wednesday Poster Session: WEPB

16:00 A half-sine type Marx generator designed for HEPS pre-kicker

HEPS is a nearly finished fourth-generation photon source with a 6 GeV energy storage ring. When machine protection is activated in the storage ring, the low beam emittance causes most particles to deposit nearly vertically on the collimator. This can result in concentrated heating, potentially leading to material melting of the collimator. Thereby, two pre-kickers are used to generate 4.52 µs half-sine magnetic fields in both horizontal and vertical directions upon receiving the protection signal, dispersing the particles throughout the entire ring to safeguard the collimator. However, during engineering construction, the circuit may have a total inductance that far exceeds the initial design, leading to inadequate voltage output from the prepared HV charging power supply. Comparing the Marx generator and the inductive adder voltage boosting topologies, the Marx generator offers a more compact and simpler design for long pulse applications. Therefore, this paper presents the design and testing of a two-stage Marx generator based on LC resonance to deliver a half-sine pulse to the pre-kicker.

Speaker: Xinzhe Zhai (Institute of High Energy Physics)

16:00 A positron beamline for channeling experiments at MAMI

The Institute for Nuclear Physics of the University of Mainz operates the accelerator complex MAMI. Outstanding qualities are the continuous beam with an excellent beam quality, a very low energy spread, as well as its extremely high reliability. All kinds of channeling experiments require such a high quality beam with a low divergence. Positrons, however, are more preferable because they have a significant longer de-channeling length. The aim the project is the preparation of high-quality positron beam using the features of the MAMI accelerator. Positrons will be created by pair conversion of bremsstrahlung, produced by a focused 855 MeV electron beam of MAMI in a 10 um thick tungsten converter target, and energy selected by an outside open electron beam-line bending magnet. A sector magnet bends back the beam. Magnetic focusing elements in between are designed to prepare in a well shielded chamber about 6 m away from the converter target a low divergence positron beam. The features of the positron beam line such as the positron rate, the beam spot size and the divergence of the positron beam will be discussed. First channeling experiments with Silicon crystals will be presented.

Speaker: Pascal Klag (Institut für Kernphysik)

16:00 A study on the pattern waveform high-voltage power supply for the rapid cycling induction synchrotron

The application of a 10 Hz repetitive induction synchrotron (IS) to the next generation of heavy ion therapy drivers is under investigation *. The IS is characterized by the use of a pulse voltage to accelerate the beam, but until now, due to technical limitations, the magnitude of the pulse voltage could not be perfectly matched to the acceleration conditions. Instead, a pulse density modulation method has been adopted. However, this method inevitably induces synchro-beta coupling, which increases beam emittance. To overcome this problem, we develop a pattern-voltage dc power supply in which the output voltage waveform has a sinusoidal half-wave shape that matches the acceleration conditions. First, a mini-model was fabricated, and comparative experiments were conducted with three different circuit schemes: (A) a bipolar-controlled full-bridge circuit, (B) a unipolar-controlled full-bridge circuit, and (C) a series connected half-bridge circuit. This paper describes the results of these tests and issues for future study.

Speaker: Katsuya Okamura (High Energy Accelerator Research Organization)

16:00 A technique to improve the energy leakage of TM020-mode cavity for Super Tau Charm Facility

TM020-mode cavity with a higher quality factor and a lower R/Q as compared to TM010 cavity is an attractive candidate for RF system of Super Tau-Charm Facility. However, the symmetrical electromagnetic field distribution at radial nodes is diluted by the introduction of a high-power input port and cavity frequency tuners. This results in the leakage of the accelerating mode and a weak damping of harmful modes. In order to address these issues, this paper proposes elliptic coaxial slots and tuning bumps on the inner wall to optimize the performance of the accelerating mode and harmful modes. Simulation results demonstrate that the energy leakage of the accelerating mode can be reduced below 1% during operation and all of harmful modes can be strongly damped.

Speaker: Masao Kuriki (Hiroshima University)

16:00 A TM020-mode cavity with choke geometry for Super Tau-Charm Facility

To meet the requirements of collider rings of Super Tau-Charm Facility (STCF) with a beam current of up to 2 A, a TM020-mode cavity with improved performance is designed in this paper. In order to address the issues of leakage of accelerating mode into the slots which has dampers inside, a choke geometry is introduced for this cavity. Through optimizations on this choke, the accelerating mode is fully reflected back into the cavity and all of harmful modes can be heavily suppressed. In addition, the nose shape and frequency tuner are also optimized in detail.

Speaker: Masahito Hosaka (University of Science and Technology of China)

16:00 Advanced power density mapping for FEA simulations of synchrotron accelerator high heat load components

Accurately simulating the thermal and mechanical effects of undulator power density distribution in high heat load components requires precise power implementation in finite element analysis (FEA) models. This study presents a novel methodology utilizing intermediate programming to efficiently map complex undulator power density distributions onto FEA models. The approach enables the placement of power density values (e.g., W/mm²) on each element surface while simultaneously calculating the grazing angles based on the insertion device's power source geometry. By automating these processes, the methodology significantly reduces the time and effort required for engineers to implement detailed power distributions in FEA simulations. This advancement not only ensures higher accuracy in modeling but also streamlines the workflow, allowing for faster evaluation and optimization of high heat load components in synchrotron radiation facilities. The proposed framework offers a practical solution for integrating advanced undulator power profiles into engineering analyses, enhancing both efficiency and reliability.

Speaker: I-Ching Sheng (National Synchrotron Radiation Research Center)

16:00 Advancements in LINAC performance for enhanced stability and control: Integration of the Libera LLRF systems into the ScandiNova modulators

For years, Instrumentation Technologies and ScandiNova have developed advanced products to optimize RF performances in LINAC applications. In 2024, the companies began integrating the Libera LLRF system into ScandiNova modulators during assembly. This innovation enables the modulators to offer enhanced operational flexibility and improved performances.
This paper will focus on mechanical integration and performance results. The integrated system enables real-time monitoring of critical signals such as drive power to the RF amplifier and klystron, as well as forward and reflected klystron power. Performance metrics include amplitude stability <0.01% RMS and phase stability <0.01° RMS.
Experimental results are presented using a ScandiNova modulator with an Sband klystron and a standard Sband Libera LLRF. Pulse-to-pulse stability measurements demonstrate consistency between conventional electrical methods and RF-based methods, achieving stability in the 10 ppm range. Electromagnetic compatibility tests confirm that the modulators do not interfere with the LLRF system. Additionally, new tools are introduced to identify components with the greatest impact on phase stability.

Speaker: Kevin Pepitone (Scandinova Systems AB)

16:00 Advancements in magnet power supply systems at KARA: enhancing stability, efficiency, and operational capabilities

The Karlsruhe Research Accelerator (KARA) has undergone a significant modernization of its power supply infrastructure, including dipole, quadrupole and sextupole magnet systems. These updates, completed by replacing the storage ring quadrupole power supplies in summer 2024, introduce improved stability, reduced energy consumption, and advanced control capabilities.
The new controls and control system integration enable new operational modes, including energy ramp-down to refill the machine or reduce radiation by dumping the beam at lower energy. This allows consecutive beam optics and collective effects testing at high beam currents without creating too high radiation losses.
The upgrades to the quadrupole power supplies further support these advancements by improving compatibility with modern control systems, ensuring reliable and efficient operation, and enabling more flexible operation modes.
This paper summarizes operational experience over a year and compares the performance of the new systems to the previous ones. It highlights improvements in control interfaces, reliability, and overall performance, showcasing the upgrades' benefits for KARA.

Speaker: Anton Malygin (Karlsruhe Institute of Technology)

16:00 Beam impact experiment to qualify the damage limits of Nb3Sn sample coils pre-irradiated to 30 MGy

A series of experiments has been carried out at CERN to derive the damage limits of superconductor strands and sample coils. The latest experiment was designed to characterize the limits of Nb3Sn racetrack sample coils impacted by a 440 GeV/c proton beam at cryogenic temperature. The effect of a beam impact on superconducting coils aged by long-term radiation exposure, however, is currently unknown. This paper outlines the preparation of an experiment to be performed at the HiRadMat facility to investigate the damage on coils which have been aged with X-rays to simulate the anticipated integral dose levels reached by the HL-LHC final focusing magnets during their operational lifetime, of 25 to 30 MGy. The damage limits for these coils will be derived and compared with the results previously obtained for non-aged coils. The design and fabrication of these sample coils, the details of the X-ray irradiation and the results from their qualification tests before beam impact is discussed. The results of energy deposition simulations that define the optimal parameters for the proton beam to be used are presented. The experimental setup and procedure are discussed.

Speaker: Dr Daniel Wollmann (European Organization for Nuclear Research)

16:00 Characterization and modeling of electropolishing for copper cavities in superconducting applications

To enhance the performance of superconducting radiofrequency (SRF) cavities, a promising solution involves depositing a superconducting material onto copper RF cavities. A prerequisite for this process is the electropolishing of the copper cavities. At Jefferson Lab (JLab), a modeling study of the electropolishing process for 1.3 GHz copper cavities was conducted. This paper focuses on two main aspects. First, the characterization of the electropolishing solution, consisting of H?PO? and n-butanol, was carried out through chemical and electrochemical analyses. This enabled the development of a comprehensive surface preparation process for the electropolishing of copper cavities, which involved defining all critical parameters such as voltage, temperature, and electrolyte flow.Second, these parameters were used as inputs for COMSOL simulations to optimize the electropolishing process. The simulations incorporated modules for secondary current density, heat transfer, and laminar flow to refine the cathode shape and enhance the process efficiency

Speaker: Sarra Bira (Thomas Jefferson National Accelerator Facility)

16:00 Compact quadrupole-sextupole magnet units for the FLUTE-cSTART injection line

One of the major goals of the cSTART project (compact STorage ring for Accelerator Research and Technology) at KIT is injecting and storing ultra-short bunches from the FLUTE linac into a very large-acceptance compact storage ring. To cope with the spatial constraints of the injection line connecting FLUTE with the storage ring three meters above, compact quadrupole-sextupole magnet units were designed, fabricated, and characterised.

In this contribution, we describe the magnetic design of these units and the underlying considerations, particularly with respect to cross-talk effects and their mitigation by design. We present the results of rotating coil and Hall probe measurements validating the magnetic design.

Speaker: Axel Bernhard (Karlsruhe Institute of Technology)

16:00 Cryocooler-based conduction cooling for 1.3 GHz Nb3Sn superconducting RF cavity

Superconducting radio frequency (SRF) cavities are, along with superconducting magnets, indispensable technologies for modern particle accelerators. The current cooling method for SRF cavities is immersion in liquid helium bath, which is ideal in terms of cooling because the entire outer surface of the cavity can be maintained at liquid helium temperature. On the other hand, using helium has several difficulties such as costs, availability, large facilities, and high pressure gas safety. Conduction cooling for SRF cavities are currently widely focused all over the world to sweep away above problems.
KEK is pushing conduction cooling technology development for 1.3 GHz Nb3Sn cavity towards beam acceleration. We have ever done several RF tests under conduction cooling by cryocoolers and copper rings on the cavity equator. In the poster, we will introduce our progress and future plan.

Speaker: Tomohiro Yamada (High Energy Accelerator Research Organization)

16:00 Cryogenic cooling of superconducting devices

Superconducting magnets, RF cavities, undulators and wigglers are widely employed for particle accelerators and cooled under the cryogenic condition below 100 K. This paper describes the cryogenic cooling schemes of superconducting devices and the sources of the cooling power capacities: refrigerators, cryoplants, and cryocoolers. Their main features, such as temperature, pressure, and cooling powers will be presented, which facilitate R&D of superconducting devices.

Speaker: Zhanguo Zong (High Energy Accelerator Research Organization)

16:00 Defects characterization of superconducting RF cavities via replica technology

The SHINE project requires more than six hundred of 1.3GHz cavities and sixteen 3.9GHz cavities for the superconducting accelerator. These cavities are from both domestic and foreign companies. Surface defects, such as cat-eyes, aluminum inclusions and scratches, are one of the most important factors strongly related to RF performance of cavities. The multiplicity of sizes, depths and locations of defects on cavities will bring different effects in RF test. Characterizing the precise data of 3D size and location of the defects is of great significance to study the corresponding relationship between the surface defects and RF performance. In this paper, we will report a technology of replicating and characterizing surface defects on the superconducting cavities in SHINE.

Speaker: Xuhao He (ShanghaiTech University)

16:00 Design and development a measurement system for magnetic tuning of undulator magnets

The permanent-magnet in-vacuum undulator technique is critical for the Taiwan Photon Source(TPS) at the National Synchrotron Radiation Research Center(NSRRC). Before installing the magnet arrays in the vacuum chamber, the phase error of the undulator is optimized by adjusting the magnetic field. Optimizing phase errors is a complex and time-consuming task. The conventional measurement method involves using Hall probes to measure the magnetic field and a stretched-wire(SW) to measure the integral field of the undulator. In this work, we propose a method for tune the local magnetic field by utilizing the correlation between the gap and the magnetic field. We have demonstrated that using gap sensors allows us to more effectively determine whether to tune the magnetic field of the upper or lower magnet array. Additionally, we have demonstrated for the first time the use of the pulsed wire measurement (PWM) method for magnetic sorting.

Speaker: Chih-Wei Chen (National Synchrotron Radiation Research Center)

16:00 Design and development of an extraction septum for the MYRRHA 100 MeV proton target facility

SCK CEN is developing MYRRHA, a large-scale Accelerator Driven System. MYRRHA shall be a subcritical nuclear reactor driven by a high-power linear proton accelerator, which sustains the nuclear reaction. In the initial phase, known as the MINERVA project, the goal is to demonstrate the high reliability requirements on the accelerator. The two primary end users of the MINERVA project are the Full Power Facility and the Proton Target Facility.
In collaboration with SCK CEN, CERN studied and designed an extraction septum for the 100 MeV Proton Target Facility. Two distinct topologies have been evaluated magnetically and tracked particle simulations have been executed to validate the designs. A preferred low-power solution has been retained for a subsequent detailed design. A final magnetic verification to confirm the mechanical design requirements has been carried out. This has allowed to develop a detailed 3D mechanical design including all manufacturing tolerances required for subcontracting the magnet fabrication to the industry.
This article covers the 2- and 3-dimensional magnetic modelling, the tracked particle simulations and the mechanical design of the septum magnet.

Speaker: Laurent Ducimetière (European Organization for Nuclear Research)

16:00 Design and Implementation of a Power Monitoring and Distribution System for the SSPA-Based RF Transmitter at NSRRC

This paper presents the design and implementation of a power distribution and monitoring system for a high-power RF solid-state amplifier (SSPA) system at the Taiwan Photon Source (TPS). The system consists of four SSPA towers delivering a combined RF power of 300 kW. Given efficiency and safety considerations, a robust distribution and protection architecture was implemented. The system features remote monitoring and control via a Modbus-connected PLC and HMI, enhancing reliability and operational insight.

Speaker: Yi-Ta Li (National Synchrotron Radiation Research Center)

16:00 Design of a 2300 W 352 MHz solid-state amplifier module with integrated EtherCAT interface for monitoring and control

For multi-unit RF amplifier systems, a 2300 W solid-state RF power amplifier module with integrated EtherCAT and USB interface has been developed. The RF amplifier section is constructed from the latest LDMOS from Ampleon with a power of 2300 W at an efficiency of 72 % and is fully shielded and offers space for adding a driver amplifier or phase shifter circuit. The module is equipped with a DIN 7/16 output connector and an N-type input connector and is housed in a metal housing of 200 x 95 x 80 mm. The cooling of the RF LDMOS is done via a CNC milled copper cooling plate that is gold-plated. The gold layer prevents chemical oxidation with other aluminum parts such as an aluminum main plate. In a multi-unit system, the EtherCAT interface provides lightning-fast and synchronous control and monitoring of parameters such as supply voltage and current, heat sink and LDMOS temperature, forward and reverse RF power. Outside the EtherCAT environment, the USB interface can be used in combination with a Windows GUI. Eight LEDs are available as visual indicators. The entire process of design, assembly and testing takes place in the Netherlands, which guarantees quality and traceability.

Speaker: William Leijenaar (Leijenaar Electronics)

16:00 Design of an online adjustable waveguide coupler for the TM020-mode cavity of proposed STCF

The Super Tau-Charm Facility (STCF) project plans to use 12-15 TM020-mode cavities for each collider ring to compensate for the beam energy loss. Each cavity is designed to provide a voltage of 0.5 MV and a power of 250 kW for the beam. Therefore, an online adjustable waveguide coupler with a power capacity of CW 300 kW has to be developed for each cavity. This input coupler has a waveguide size the same as the half-height WR1500. The coupling between the cavity and the half-height WR1500 is realized by a rectangle hole with blending. This paper presents the electromagnetic design, the multipacting simulation, and the thermal and stress analysis of the input coupler in detail.

Speaker: Zachary Liptak (Hiroshima University)

16:00 Design of FFA magnet for the laser-hybrid accelerator for radiobiological applications (LhARA)

LhARA, which stands for “Laser-hybrid Accelerator for
Radiobiological Applications”, is a novel and flexible facil-
ity dedicated to research in radiobiology. A proton beam
of energy up to 15 MeV can be produced by a laser driven
source, the beam then enters a Fixed Field Alternating (FFA)
gradient accelerator for acceleration to produce a variable ex-
traction energy between 15-127 MeV. To avoid uncontrolled
beam loss, the operational tune was picked carefully to avoid
resonances. The magnetic field must be adjusted to ensure
that the tune stays at the same working point for different
energy ranges. The FFA ring uses combined-function spiral
magnets, which create a radial magnetic gradient through
distributed conductors wrapped around the pole, each car-
rying a different current. A three-dimensional study was
carried out in OPERA 3D and the parameters of the magnet
were optimized. The results showed that resonances up to
fourth order were avoided for the entire range of acceleration
for different operational energies entire range of acceleration and different operational energies.

Speaker: Ta-Jen Kuo (Imperial College London)

16:00 Design of high frequency pulse power supply for electron gun

The grid control power supply of the electron gun of the free electron laser (FEL) is a high frequency pulse power supply (HF-PPS), which has a special time structure. The macro pulse repetition frequency of the HF-PPS designed in this paper is 10 Hz, and the micro pulse repetition frequency is 476 MHz.

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

16:00 Design of normal conducting quadrupoles for the spin rotator section in the EIC electron storage ring

The interaction region IR6 in the Electron Storage Ring of the planned Electron Ion Collider facility at Brookhaven National Laboratory includes a section to rotate the electron spin into or out of the longitudinal direction. This section consists of superconducting solenoids, and normal conducting dipoles and quadrupoles. The geometry and field gradient requirements of the quadrupoles pose a challenge in their design with regards to yoke saturation and thereby field quality. Electromagnetic design of one such quadrupole is the focus of discussion in this article. The design process involves optimization of the pole tip, yoke and conductor size using two and three-dimensional finite element method tools.

Speaker: Boris Podobedov (Brookhaven National Laboratory)

16:00 Design of prototype magnets for FETS-FFA

Fixed Field Alternating gradient accelerators (FFA) hold
promise for pulsed high intensity applications. No such
FFA has been constructed to date; therefore a prototype -
the Front End Test Stand-FFA (FETS-FFA) has been pro-
posed to explore the feasibility of using FFA technology for
the next generation spallation neutron source, ISIS-II. A key
component of this prototype is its main magnets, which must
meet several critical requirements: maintaining zero chro-
maticity during acceleration, offering tune point flexibility,
and providing a large dynamic aperture. The selected lattice
incorporates a doublet spiral magnet design for more flexi-
ble operations in the tune space. The magnetic field profile
is generated by distributed conductors wound over the pole
face; a 3D analysis using OPERA software was conducted to
evaluate the settings necessary to produce the desired field.
The cell tune variation was found to be within ±0.0015 hor-
izontally and ±0.002 vertically, for four different working
tune points.

Speaker: Ta-Jen Kuo (Imperial College London)

16:00 Development of a 13 kV SiC-MOSFET-based pulsed power supply for evaluating metallic materials under high electric fields

To perform high electric field experiments for evaluating the vacuum breakdown characteristics of accelerator materials, we have developed a high-voltage pulsed power supply capable of providing a 10 kV peak voltage, 1 µs pulse width, and 1 kHz repetition rate. This system is designed to reliably apply intense fields to metallic electrodes with load capacitances up to 650 pF. To ensure operational reliability and prevent potential equipment damage, it incorporates an interlock system that halts operation when load short-circuits or external interlock signals are detected. By employing a 13 kV SiC-MOSFET developed under the Tsukuba Power Electronics Constellation (TPEC), we reduced the number of components and improved overall reliability. This report presents the technical features and performance of the power supply, demonstrating that it meets the operational specifications necessary for evaluating candidate materials under high electric field conditions.

Speaker: Hiroaki Kamezaki (Pulsed Power Japan Laboratory Ltd.)

16:00 Development of a compact high voltage pulse power supply of MARX-type for muon linac klystron

We have been developing a compact pulse power supply with output pulse waveform specifications of 75kV/40A/50us/25Hz. This power supply is used to drive klystron for muon linac, which requires high stability and reliability. Next-generation power semiconductor SiC-MOSFETs with excellent characteristics of ultra-high breakdown voltage and low loss at 13kV, which were realized through the technological development of wide bandgap semiconductor devices, are used. Combining this SiC-MOSFET with the MARX circuit will realize a more compact pulse power supply with lower loss than conventional ones. In addition, it can be applied to portable accelerators in the future. In this presentation, the circuit design of the MARX power supply will be reported.

Speaker: Tomohiro Takayanagi (Japan Atomic Energy Agency)

16:00 Development of a modular corrector magnet power supply with N+1 redundancy for TPS facilities

This study presents a multi-module parallel current output system based on the correction magnet power supplies (CMPS) of the TPS storage ring. An N+1 re-dundant control interface card was designed to enable high-current, bipolar modular parallel output. The system integrates external DCCTs and current feed-back signals from the internal module. After PI com-pensation, these feedback signals are compared with the reference current to compute correction values distributed to each CMPS for closed-loop current con-trol. Each CMPS module provides an output of ±48 V/±10 A, and up to eight modules can be connected in parallel for a maximum output of ±80 A. Experimental results demonstrate long-term output current stability within 0.6 mA (or 7.5 ppm), with current noise spectra primarily below 500 µA. The system also supports N+1 redundancy and bipolar current output, offering a stable and flexible solution for magnet power control.

Speaker: Bao-Sheng Wang (National Synchrotron Radiation Research Center)

16:00 Development of a variable power divider for the ILC power distribution system

The R&D of the radio frequency (RF) power distribution system (PDS) for the International Linear Collider is ongoing. The PDS is designed to drive 39 superconducting RF (SRF) cavities by a 10 MW multibeam klystron. The key feature of the PDS is the usage of power dividers and phase shifters, which allow driving all cavities below their respective operational limits over the whole flattop. This is necessary to maximize the beam energy. Following the design of the variable power divider (VPD) developed at SLAC, we intend to combine power dividing and phase shifting capabilities in a single device. The VPD consists of two folded magic tees (FMTs), four small WR650 waveguides, and two U-bends. The U-bends serve as variable phase shifters. The FMTs have been designed, fabricated, and tested. A prototype for the checking the working mechanism of U-bend phase shifter was produced. Preparations for its high-power testing are currently underway.

Speaker: Prakash Joshi (The Graduate University for Advanced Studies, SOKENDAI)

16:00 Development of compact ultra-high power pulsed power supply

Currently, pulsed power supply systems with output power of several GW, output voltage of several hundred kV, and pulse width of 100 ns are difficult to miniaturize and portability is a limitation for industrial applications. We are developing a pulsed power supply with an output power of 4 GW, an output voltage of 200 kV, and a pulse width of 100 ns, which is 1/20th the mass of conventional products, in order to solve this limitation. In this presentation, we will give an overview of the system design and the current status of the development.

Speaker: Yukiko Hirose (Pulsed Power Japan Laboratory Ltd.)

16:00 Development of moving long coil magnetic measurement system based on HALF magnets

Hefei Advanced Light Facility (HALF) consists of two main components: the injector and the storage ring, the core of the facility includes nearly one thousand magnets, of which there are more than one hundred conventional dipole magnets and longitudinal gradient bend magnets.The longitudinal integral field and its uniformity of these dipole magnets are typically measured by the Hall probe measurement system, which takes a long time to measure, and the measurement accuracy of the uniformity repeatability of the integral field can only reach 0.01%. The accuracy of the integral field uniformity of the long coil magnetic measurement system can reach less than 0.01%, and the measurement accuracy of the uniformity repeatability of the integral field can reach less than 0.005%. Therefore, to efficiently and accurately measure the uniformity of the integral field, there is a necessity to develop the moving long coil magnetic measurement system. This paper develops a moving long coil magnetic measurement system based on the technical requirements for the measurement of the integral field of dipole magnets in the HALF project.

Speaker: Weihao Zhu (University of Science and Technology of China)

16:00 Development of ultra high power compact X-band pulse compressor

We have developed a new SLED-type RF pulse compressor for powering ultra-high gradient X-band photoinjectors with pulse lengths shorter than 10 ns. Klystrons capable of generating these short pulses at multi-MW levels are non-existent. However, RF pulse compression is an alternative technique used to increase klystron output peak power at the cost of pulse length. Over the years, we have developed numerous pulse compression systems, including super-compact SLEDs for X-band transverse deflectors at SLAC’s LCLS and LCLS-II. Our new compact pulse compressor uses spherical cavities with axially-symmetric TE modes which have no electric field on the cavity surface. This allows our new SLED to potentially achieve higher peak RF power compared to the LCLS-II SLEDs. We present the design of this SLED composed of two spherical cavities and a waveguide hybrid with TE01 circular waveguide ports. During high power test this SLED produced peak RF power up to 317 MW.

Speaker: Ankur Dhar (SLAC National Accelerator Laboratory)

16:00 Development status of a NbTi conduction-cooled superconducting quadrupole magnet combined with dipole correctors for the ILC main linac

In the International Linear Collider (ILC) main linac, superconducting quadrupole (SCQ) magnets combined with dipole correctors, together with superconducting radio frequency (SRF) cavities, will be used to transport and accelerate electron and positron beams to the collision point. The SRF cavity accelerates the beam up to 125 GeV per side, the SCQ focuses the beam, and the dipole collectors steer the beam and transport it along with the geoid.
A 5-year plan to manufacture one ILC-type cryomodule began at KEK in 2023 with international collaboration. A prototype SCQ is being manufactured currently. It consists of 4 sets of race-track coils and each set has three coils for quadrupole, vertical dipole, and horizontal dipole. An excitation test will be performed at cryogenic temperature with a newly fabricated stand-alone test cryostat by March 2026. In the poster, the status of SCQ fabrication and the stand-alone test cryostat will be reported.

Speaker: Tomohiro Yamada (High Energy Accelerator Research Organization)

16:00 Efficient nonlinear simulations of the fast corrector magnets for PETRA IV

Fast orbit feedback systems are an important component in fourth-generation synchrotron radiation sources such as PETRA IV at DESY in Hamburg, Germany. These control systems are designed to stabilize the particle orbit, i.e., to correct deviations from the design orbit due to various disturbances. To that end, such a system employs fast orbit corrector magnets, which must be powered at frequencies up to the kilohertz range. This leads to significant eddy current effects that must be predicted via finite element simulations. Therefore, extensive simulation studies have already been conducted.
These simulations did not, however, consider the magnetization curve’s nonlinearity since doing so requires prohibitive computational effort when using commercial software. Hence, we have constructed a dedicated method, based on a combination of the harmonic balance finite element method and homogenization schemes, to enable nonlinear simulations. This contribution outlines the general idea and application of our method to the corrector magnets of PETRA IV and presents the most important findings regarding the impact of the nonlinear magnetization curve on the magnet’s performance.

Speaker: Dominik Moll (Technical University of Darmstadt)

16:00 ESS RF power station (400 kW @ 352 MHz) for spokes: issues identified due to soak testing and operational insights

The first section of the ESS superconducting linac is the Spoke Linac, which raises the beam energy from 90 MeV to 216 MeV. This is achieved by 26 superconducting spoke cavities, housed in 13 cryomodules. These cavities are powered by Spoke RF Power Stations (RFPS), each delivering a maximum power output of 400 kW at 352 MHz. This power is generated by combining the outputs of two tetrode TH595A-based amplifiers using a hybrid combiner.
The RFPS units are supplied by Elettra as part of Italy's in-kind contribution to the ESS. To date, 27 RFPS units have been delivered to ESS, with 26 installed and commissioned in the ESS gallery. The RFPS units have been utilized to test and qualify various systems. The interfaces for the Personal Protection System (PSS) and the Machine Protection System (MPS), both critical for beam operation, have also been successfully validated. Additionally, the RFPS units were employed in the warm and cold coupler conditioning of the spoke cavities. They will continue to be used for cold cavity conditioning and beam commissioning.
This paper addresses the issues identified during soak testing and the corresponding mitigations that were implemented.

Speaker: Rutambhara Yogi (European Spallation Source)

16:00 ESS superconducting linac cold technical commissioning

The European Spallation Source (ESS) superconducting linear accelerator (linac) represents a key component in delivering high-intensity proton beams for cutting-edge neutron science research. This paper details the first cold technical commissioning of the superconducting linac in 2MW configuration, focusing on the performance validation of cryomodules, superconducting radio-frequency (SRF) cavities and associated systems.

Speaker: Nuno Elias (European Spallation Source)

16:00 Faint magnetic field shield using the Meissner effect

Magnetic fields play an important role in many physics studies, and many measurement items in physics experiments require control of micro magnetic fields. Although superconducting accelerating cavities can generate high electric fields at low power, the material niobium is a type-II superconductor, and trapping the ambient magnetic flux during the superconducting transition increases the operational losses. For this reason, micro magnetic shielding is important, and strengthening micro magnetic shielding is essential when aiming for further power saving. Therefore, we have begun to study the shielding effect of micro magnetic fields based on the Meissner effect of superconductors, which are perfectly antimagnetic. We have selected AMR (Anisotropic-Magneto-Resistive) type 3-axis sensors, drive five 3-axis sensors under cryogenic temperature, and bring their signals to the room temperature side with nine cables, including the power supply, by multiplexing. The signals were calibrated with the output of the FluxGate under cryogenic conditions. Preliminary results show that the amount of flux rejection is generally monotonically increasing with temperature gradient.

Speaker: Yoshihisa Iwashita (Osaka University)

16:00 Field measurements of a short period helical superconducting undulator

Superconducting undulators (SCUs) may be capable of generating stronger magnetic fields at shorter periods than can be achieved using permanent magnet undulators. Therefore, the range of x-ray wavelengths that an XFEL facility can generate for users could be expanded by exploiting SCU technology.
Prototyping work is ongoing at STFC to build a helical superconducting undulator (HSCU) with 13 mm period and 5 mm magnetic gap designed for future XFEL facilities. As part of this work, a test cryostat has been built to cool 325 mm long prototype magnets to 4 K and to measure the field profile of the HSCU using a cryogenic Hall sensor. The magnetic field measurements are necessary to confirm the peak-to-peak field quality and trajectory wander of an electron beam through the device. These quantities must be measured to understand the impact of the HSCU on the FEL radiation output. The trajectory wander can be minimised through the use of field integral corrector coils at either end of the HSCU coil.
We present here a description of the test cryostat and the results of the magnetic field measurement regime performed on the prototype HSCU coil.

Speaker: Alex Hinton (Science and Technology Facilities Council)

16:00 First magnetic field penetration results of multilayer samples and A15 materials for the use in SRF applications

Superconducting radiofrequency cavities made of bulk Nb are reaching their theoretical limits in the maximum accelerating gradient, Eacc, where Eacc is limited by the maximum magnetic field, B, that can be applied on the surface of the accelerating cavity wall. To increase Eacc, the maximum B field, Bmax, which can be applied to the surface, must also be increased. The A15 materials or multilayer structures are the potential solution to increase Bmax., Since coating and RF testing of full size RF cavities is both expensive and time consuming, one need to evaluate new ideas in superconducting thin films quickly and at low cost. A magnetic field penetration experiment has been designed and built at STFC Daresbury Laboratory to test superconducting samples (< 100 mm ). The facility produces a parallel DC magnetic field, which applied from one side of the sample to the other similar to that in an RF cavity. The facility applies an increasing magnetic field at a set temperature to determine the field of full flux penetration which can give an insight into the quality and structure of the superconducting structure.

Speaker: Liam Smith (Science and Technology Facilities Council)

16:00 HEPS Magnet power supply with magnetization and demagnetization functions

After the magnet is magnetized, due to the characteristics of the magnetization curve, there will still be residual magnetism in the magnetic field even after the magnetizing power supply is turned off. When measuring the same magnet multiple times, the residual magnetism not only affects the measurement of the magnetization curve but also impacts surrounding devices and instruments. In the magnetic measurement work prior to the installation of the magnet, it is sometimes necessary to demagnetize the already magnetized magnet. The magnetic measurement power supply described in this article can operate in both magnetization and demagnetization modes, where the magnetization mode provides a DC current with high stability for magnetization, and the demagnetization mode automatically demagnetizes the magnet.

Speaker: Xiaoling Guo (Chinese Academy of Sciences)

16:00 High repetition tests of a pulsed power supply using SiC-MOSFETs for a fast kicker system in KEK-PF

A pulsed power supply (PPS) using SiC-MOSFETs is an essential component in the camshaft-bunch system at KEK-PF *. The system requires the PPS to generate half-sine pulses with a peak current of 500 A, a pulse width of 200 ns, and a repetition rate (rep-rate) of 800 kHz. We have developed a prototype PPS consisting of a resonant circuit (RC) to generate half-sine pulses with a SiC-MOSFET switching module (SWM). The SWM, manufactured by NexFi Technology, has a rated voltage of 24 kV and a maximum rep-rate of 400 kHz. The main challenges in RC development were to reduce the charging time of the RC and power consumption during high-frequency operation. Additionally, film capacitors used in a previous prototype * required replacement because their permittivity had degraded during high-frequency operation. To overcome these challenges, we designed a RC with an energy recovery circuit, which reduced the charging time to 1 µs and power consumption by 90%. To ensure reliability, the film capacitors were replaced with vacuum capacitors. This report presents the prototype design, performance tests at a rep-rate of 400 kHz, and evaluation of long-term reliability at a rep-rate of 100 kHz.

Speaker: Satoshi Shinohara (High Energy Accelerator Research Organization)

16:00 High-power, high-repetition-rate X-band power source at X-LAB, the X-band laboratory for accelerators and beams at the University of Melbourne

The X-LAB has been commissioned at the University of Melbourne. A key project within this laboratory involves rehoming half of the CERN high-gradient X-band test stand, XBOX3, now known as Mel-BOX. This initiative aims to validate the performance of high-gradient traveling wave accelerating structures operating at a frequency of 12 GHz. Mel-BOX is employed to evaluate the performance of these accelerating structures under high-power pulsed RF conditions.
Two TD24 high-gradient structures, previously conditioned at CERN, were reconditioned at X-LAB after being shipped and stored for five years. Additional components have also been tested, including a compact pillbox-type RF window with traveling waves in ceramic, SLED-I type pulse compressors with a novel piston design, and high-power loads fabricated via 3D titanium printing and 1-meter-long stainless steel.
As with XBOX3, Mel-BOX utilizes the combined power of two high-average-power klystron units to feed two test slots at a repetition rate of up to 400 Hz. Additionally, there are plans to leverage this technology as a foundation for developing compact accelerators for medical and university applications.

Speakers: Paul Giansiracusa (The University of Melbourne), Matteo Volpi (The University of Melbourne)

16:00 Higher order mode power in superconducting cavities of SuperKEKB with high current operation

SuperKEKB is a high-current machine for high-luminosity.Eight higher order mode (HOM) damped single-cell superconducting cavities accelerated an electron beam in the main ring since KEKB.
A strong dependence of the absorbed power of the ferrite HOM dampers on
the number of bunches was observed in 2022 operation. One of the reasons for this is thought to be a build-up effect of some parts of the HOM caused by narrow bunch spacing. It was found in the last operation that this problem has an individual difference for each cavity. In particular, TM011 can propagate on the LBP side, and the frequency is quite close to an integer multiple of the RF frequency, the build-up effect is remarkable. As the accelerator is expected to reach its design current in the future, the HOM power will also increase and ferrite HOM dampers will have to cope with the increasing HOM power resulting from the build-up. This report provides an overview of the status of the superconducting cavity HOMs last
operation in 2023-2024 and a countermeasure plan for the future.

Speaker: Takafumi Okada (High Energy Accelerator Research Organization)

16:00 Highly stable pulse operation of 476 MHz solid-state amplifiers with a precision of 0.01 degrees at SACLA

We have introduced new 476MHz solid-state pulsed amplifiers to the X-ray Free Electron Laser facility, SACLA. The 476 MHz booster cavity requires high stability and reliability with a 100 kW power for 50 us pulse width. Previously, an Inductive Output Tube (IOT) was employed for this purpose. However, due to the reduced operational range caused by aging of IOT components and increasing difficulties in obtaining maintenance parts, a transition to solid-state amplifiers has been undertaken. The modular configuration of solid-state amplifiers with a combiner allows continuous operation even in the event of module failures and facilitates easy repairs. Additionally, their design eliminates the need for high voltage, as required by IOTs, which is expected to improve fault tolerance. This poster presents the operational status of the solid-state amplifiers, along with evaluation results of pulse-by-pulse stability with a precision of 0.01% for the amplitude and 0.01 degrees for the phase, respectively.

Speaker: Eito Iwai (Japan Synchrotron Radiation Research Institute)

16:00 Identifying 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. 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)

16:00 Impact of ion and neutral angular distribution on thin film deposition in HiPIMS and bipolar HiPIMS

Unipolar and bipolar High Power Impulse Magnetron Sputtering (HiPIMS) are widely used techniques for depositing superconducting thin films, utilizing various magnetron configurations such as planar and cylindrical. In this study, ion energy and flux were measured from both planar and cylindrical magnetrons under varying pressure and power conditions, using mass spectrometry and Retarding Field Energy Analyzers (RFEA). To investigate the angular dependence of these configurations, diagnostics were performed over a full 180° sweep of the sputtered material. A Langmuir probe was employed to measure the current-voltage (I-V) characteristics of the plasma. The angular dependence of the deposition rate was evaluated using a charge-selective quartz crystal microbalance and compared across the different magnetron configurations. Superconducting Nb films were then deposited at various angular positions, with substrates either grounded or biased, and analyzed via X-ray Photoelectron Spectroscopy (XPS) and Scanning Electron Microscopy (SEM). The findings of this work provide insights into optimizing deposition rates and film growth, with potential in enhancing 1.3 GHz cavity coating.

Speaker: Stephane Simon (University of Liverpool)

16:00 Insertion devices for the ultralow emittance storage ring ALBA II

The ALBA synchrotron light source is undergoing a transformative upgrade to become a state-of-the-art fourth-generation facility, known as ALBA II. This upgrade will reduce the electron beam emittance to approximately 200 pm·rad, achieving a twentyfold improvement over the current performance. A key goal of the project is to maintain the existing source points for the insertion device beamlines; in fact, most of the currently installed devices will be kept after the upgrade. Nevertheless, selected insertion devices will be replaced to fully exploit the enhanced capabilities of the upgraded electron beam. Additionally, two available straight sections will be utilized to support the development of ultra-long beamlines exceeding 250 meters, enabling advanced nano-probing and coherence-based experimental techniques. This paper outlines the strategic plans for the new insertion devices, detailing the design criteria and the constraints guiding their development.

Speaker: Jordi Marcos (ALBA Synchrotron (Spain))

16:00 Kicker magnets for fast-switching elliptical polarized undulators beamline of the TPS

The variation of polarized light is a critical characteristic of synchrotron radiation sources. To accommodate diverse user needs and enable helicity switching, a soft X-ray beamline has been designed to alternate the helicity of polarized undulator radiation. This is achieved by switching between two undulators, configured to provide right and left circularly polarized radiation, respectively.
To separate and select these two circularly polarized photon beams, six kicker magnets are installed in the straight section. This paper details the design considerations, fabrication processes, and field measurement results of these kicker magnets, emphasizing their role in achieving seamless helicity switching and supporting the beamline’s functionality for cohabitation of multiple users.

Speaker: Chin-Kang Yang (National Synchrotron Radiation Research Center)

16:00 Linear weight optimization of local magnetic field sensors for the integral field measurement in accelerator magnets

The measurement of the integral magnetic field in accelerator magnets is crucial for the precise control and operation of particle accelerators. Traditional methods often rely on a fixed distribution of magnetic field sensors or long integral coils. Nonetheless, integral coils are sometimes unavailable in the magnet bore.
This study presents an approach to enhance integral magnetic field measurements through the linear weight optimization of local magnetic field sensors. Our methodology involves strategically placing and weighing sensors within the magnet to minimize errors between the measured and actual integral magnetic fields for different powering cycles. We employ optimization algorithms to determine the optimal linear combination of sensor readings that best approximates the integral field. This process improves measurement accuracy and reduces the number of required sensors.
We validate our approach through simulation and experimental setups. The results indicate that our optimized sensor placement and weighting scheme can be effectively implemented in existing accelerator systems, offering a scalable solution for enhancing particle accelerator performance.

Speaker: Carlo Petrone (European Organization for Nuclear Research)

16:00 LIPAc RF system commissioning: busting one EMC problem at a time

Addressing electromagnetic compatibility (EMC) issues at the design stage is important. However, for a prototype like the Linear IFMIF Prototype Accelerator (LIPAc) and its RadioFrequency (RF) system providing over 2 MW of RF power, problems during the commissioning have to be expected. Random interlocks and probability of occurrence increasing with the number RF modules, the power level or the duty cycle are often evidences of EMC problems, sometimes known as RF noise. Those conditions are difficult to reproduce by the manufacturers and if no margins are considered, they need to be addressed by a dedicated team onsite*. Two solved EMC problems will illustrate the basics of the mitigation strategy: locate and stop the RF noise at the source or protect the victims from the RF noise. The first approach is applied on the air cooling: the noise from an inverter, driving a motor over tens of meters of cables, affected multiple systems sharing the same cable tray and had to be fixed at its source. The second way is applied on the tetrodes high voltage input monitor, affected by RF leaking probably from the tetrode: a source difficult to stop that called for a protection of the victim.

Speaker: Jean-Pierre Adam (Fusion For Energy)

16:00 MagCCT - magnetic field calculation and analysis code for CCT magnet

In order to develop a lightweight gantry for proton therapy, the canted–cosine–theta (CCT) superconducting magnet was considered to apply in the gantry development. The code MagCCT intended for magnetic field calculation and analysis for CCT magnet is described. The main features of the MagCCT are that it can calculate the magnetic fields of 3 different magnets: curved CCT, straight CCT and solenoid, analyzing harmonic field, and an easy-to-operate GUI interface. The usage of matrix operation ideas and parallel computing is a key issue in the MagCCT development. Comparison of magnetic field calculation results from MagCCT and those from TOSCA was presented.

Speaker: Zou Wu (Institute of Plasma Physics)

16:00 Magnetic circuit design and consideration for HTSW using 12mm HTS tape

The National Synchrotron Radiation Research Center (NSRRC) is focused on the application of 2G high-temperature superconducting tape (2G-HTS) for the insertion device in the Taiwan Photon Source (TPS) synchrotron ring. A preliminary design for a 2G-HTS wiggler (HTSW) is being developed, with considerations for sharing the SRF straight-section to make efficient use of space. The target field strength of the HTSW is 3.5 T, chosen to avoid increasing electron beam emittance. The HTSW is also designed to operate using a cryogen-free cryostat with a cryocooler to reduce liquid helium consumption. Safety margins for the current density applied to the HTS tape have been considered to prevent quenching during operation. Various parameters of the HTSW have been optimized and discussed to meet operational requirements, and a set of suitable parameters for HTSW in TPS is presented in this letter.

Speaker: Jyh-Chyuan Jan (National Synchrotron Radiation Research Center)

16:00 Magnetic design of the cSTART magnets

The KIT project cSTART (compact STorage ring for Accelerator Research and Technology) aims to store ultra-short electron bunches in a very-large-acceptance compact storage ring. The magnetic lattice of the storage ring is laid out for a variety of beam optics, including ultra-low positive and negative alpha as well as isochronous optics. These put high demands on the magnet quality and alignment. The spatial constraints for the storage ring impose further challenges on the magnet design. In this contribution, we give an overview of both the challenges and solutions for the cSTART storage ring magnet design.

Speaker: Axel Bernhard (Karlsruhe Institute of Technology)

16:00 Magnetic measurement of a decommissioned insertion device at the Canadian Light Source

The Canadian Light Source has decommissioned three insertion devices in recent years, replacing each with upgraded devices. The decommissioned devices are planar undulators that have seen approximately 15 years of operation in a 2.9 GeV storage ring, two being out-of-vacuum devices with 45 mm and 185 mm periods and one being an in-vacuum 20 mm device. In this paper we present magnetic measurements of the decommissioned 185 mm device (U185) with comparisons against the original measurements from before it was put into service.

Speaker: Cameron Baribeau (Canadian Light Source (Canada))

16:00 Magnetron-driven superconducting linacs for UNF transmutation

We describe a program to develop 805 MHz magnetron power sources to enable a cost effective one GeV Linac that is capable of CW operation at greater than 50 MW beam power. Compared to the klystrons now used at the ORNL SNS, magnetrons have about a factor of ten lower capital cost ($1/W vs $10/W) and much higher wall power to beam power efficiency (almost 90% vs 50%).
Two applications under consideration to ARPA-E are to use a spallation target driven by a high power proton Linac to produce copious neutrons to induce transmutations of all actinides in UNF for energy production or to destroy unwanted elements that have been extracted from stored UNF.

Speaker: Michael Neubauer (Muons (United States))

16:00 Measurement of magnetic field characteristics using the stretched wire system

In order to explore an efficient and accurate method for measuring the magnetic field information of accelerator magnets, this paper used the stretched wire system to measure a quadrupole magnet prototype of Hefei Advanced Light Source. In the measurement process, the integral field of the magnet at multiple points was first measured to calculate the magnetic center and multipole components of the magnet, and the influence of various measurement methods on the multipole components of the magnet was explored. Furthermore, the method of measuring magnet deflection angle using the stretched wire system and the method of correcting multipole components through magnet deflection angle were explored. The measurement results indicate that the stretched wire system has sufficient functionality and accuracy to measure the magnetic field information of the magnet.

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

16:00 Multicell parameterisation for sensitivity analysis and uncertainty quantification of elliptical accelerator cavities

Elliptical cavity geometries are typically parameterised using a canonical set of variables that define the shape of the cavity half-cells. In multicell cavity optimisation, the mid-cells are modelled with identical dimensions, while the end-cells are optimised to ensure good field flatness. However, manufacturing tolerances can introduce slight variations between individual half-cells, as cavities are produced with separate dumb-bells, which are thereafter welded together. To address these variations, a multicell parameterisation is proposed, where each half-cell is defined by its own set of variables. This parameterisation method offers a more accurate representation of real-world cavity geometries and facilitates a detailed analysis of the impact of geometric uncertainties on cavity performance. A sensitivity analysis is presented to quantify the influence of each independent geometric variable on key performance metrics, providing valuable insights for optimising both cavity design and manufacturing processes.

Speaker: Sosoho-Abasi Udongwo (University of Rostock)

16:00 Nanometer sensitive vibration measurement system R&D status for SuperKEKB final focus

SuperKEKB, a double ring circular collider with 7 GeV electron and 4 GeV positron beams, utilizes “nano-beam collision scheme” in which low emittance beams collide at large crossing angle. Positional fluctuations of the colliding beams are predicted to have a deleterious impact on luminosity; therefore, it is important to measure position oscillation of its superconducting quadrupole Final Focus (FF) magnets. KEK has developed, in collaboration with Brookhaven National Lab, a stabilized pickup-coil system to measure the magnetic field center oscillations of FF quadrupoles. This system is currently undergoing checkout and calibration at KEK using a permanent magnet quadrupole as a FF stand-in. In this paper, we will report on the measurement system status and our calibration results. This work is relevant for any high-luminosity collider that uses few-nanometer sized beams such as the proposed future ILC and FCC-ee Higgs Factories.

Speaker: Ryuichi Ueki (High Energy Accelerator Research Organization)

16:00 Operation status of superconducting RF system in SuperKEKB with high beam current

SuperKEKB continues the operation with the aim of achieving high luminosity. The beam current has already exceeded 1.3 A in the electron ring and 1.6 A in the positron ring. Eight superconducting RF (SRF) systems are operating in the electron ring. The SRF system including cavities, input couplers, HOM dampers, and so on was designed for KEKB and modified to handle the higher beam current of SuperKEKB. The SRF system is operating stably without any major problems. There are many issues that need to be resolved, such as large beam power and HOM power increasing with beam current, and various risks of failure due to aging of the system. To maintain stable SRF system operation, it is essential to establish an anomaly detection system and methods for assessing and recovering system performance. We will report on the operating status of the SRF system in the high beam current and countermeasures for the issues.

Speaker: Michiru Nishiwaki (High Energy Accelerator Research Organization)

16:00 Optimization of deposition parameters of Nb3Sn thin film on copper with and without buffer layer

In this study, superconducting Nb3Sn films were synthesised on different substrate such as sapphire, diamond turned copper and polished Nb, by DC magnetron sputtering from a single stoichiometric alloy Nb3Sn target. The structural, morphological and superconducting properties of the films were investigated. The effect of different deposition and substrate was examined. The film properties are characterized by XRD, SEM, EDX, SIMS and XPS. The DC superconducting properties of the films deposited on sapphire are characterized by a four-point probe measurement and squid magnetometer down to cryogenic temperatures. The RF surface resistance and critical temperature of films deposited on copper was measured over a temperature range of 4–23 K using 8.7 GHz choke Nb cavity. As-deposited Nb3Sn films on sapphire had a superconducting critical temperature of 18.26 K for optimum deposition condition. For the films deposited on copper and niobium has Tc of 16.5 K to 17.5 K , the surface resistance for direct 2.5 µm thick Nb3Sn, on copper was 25μΩ, which increased by two orders of magnitude when deposited on buffer layer of 4 µm thick Nb.

Speaker: Reza Valizadeh (Science and Technology Facilities Council)

16:00 Performance Analysis and Stability Enhancement Plan for the Sextupole Magnet Power Supply in Storage Ring

Since its official operation in 2016, the Taiwan Photon Source (TPS) has been dedicated to providing a stable and high-quality synchrotron radiation light source. The TPS storage ring is divided into 24 sections, each equipped with 7 sextupole power supply units, totaling 168 units. These power supplies are responsible for delivering precise and stable current to drive the sextupole magnets. This paper focuses on evaluating the long-term operational stability of the sextupole power supply system since its commissioning and proposes a targeted upgrade strategy to address potential reliability issues. To enhance overall system stability and yield, and to effectively reduce the frequency of beam trips caused by power supply faults, an upgrade plan involving the adoption of ultra-high-precision power supplies has been proposed. In addition, the removed high-precision power supplies will be repurposed as spares to improve system redundancy and fault response capability. The upgrade project is scheduled for full implementation by 2028. A pilot installation has already been completed in Cell 22, and successful electron beam storage was achieved at the end of 2024. Preliminary assessments suggest that, upon completion, the upgrade will reduce the number of beam trip events by approximately 2 to 3 times per year and decrease the total annual downtime by around 4 to 6 hours, thereby significantly improving the operational reliability of the TPS storage ring and the quality of service provided to users.

Speaker: Yong Seng Wong (National Synchrotron Radiation Research Center)

16:00 Performance on high-power test bench of RF couplers for the LIPAc’s RFQ

The Linear IFMIF Prototype Accelerator (LIPAc) in Rokkasho, Japan, designed to accelerate p+ to 4.5 MeV and D+ to 9 MeV at 62.5 mA and 125 mA in Continuous Wave (CW) mode, respectively, is under commissioning and about to enter into its final stages. A high-power test bench was developed for the testing and conditioning of the Radio-Frequency (RF) couplers of the RF Quadrupole (RFQ) cavity. The processing, requiring thermomechanical validation up to 200 kW and CW, is currently ongoing. Several tests were done, during which multipacting and thermal outgassing was observed in numerous power bands, particularly at 70 - 90 kW for the couplers, which is crucial for RFQ conditioning at nominal voltage. Subsequent tests showed that the cavity and couplers performed as expected at forward power levels close to beam operation (~ 160 kW).

Speaker: Luis Gonzalez Gallego Sanchez Camacho (Consorcio IFMIF-DONES España)

16:00 Permanent magnet version of longitudinal gradient bending magnet for Korea-4GSR Project

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. The initial design was using conventional electrical excitation, but the design is changed to use permanent magnet (Sm2Co17) to minimize energy costs. In this report, the physics design and prototyping is described including field integral, field tuning, and temperature compensation scheme.

Speaker: Beom Jun Kim (Pohang Accelerator Laboratory)

16:00 Predicting LANSCE klystron health and performance

Beam production through the LANSCE accelerator is currently disrupted due to lack of critical klystrons spares that power the Side Coupled Cavity Linear accelerator (SCCL). The situation is so dire that the facility had to compromise running beam at 100MeV for 2024 run cycle instead of its nominal 800MeV. This project aims to predict the future performance of those critical klystron units through upgrading our current testing capabilities and developing a prediction model that can warn about klystron failures before they happen. This paper will cover improving current measurement, diagnostics, and controls, developing initial klystron health and performance prediction model and automating expert dependent klystron testing. This project will increase klystron reliability for the SCCL enabling LANSCE to provide reliable 800MeV proton beam for the upcoming run cycles.

Speaker: Aditya Waghmare (Los Alamos National Laboratory)

16:00 Preliminary study of a cryogen-free cryostat for a low-temperature superconducting magnet

This report details the mechanism design and heat load budget for a cryostat that replace liquid helium and liquid nitrogen with commercially available cold heads (cryocoolers). However, to ensure the proper functioning of cryogenic superconducting magnets with the limited cooling capacity of cryocoolers, careful management of heat transfer, insulation, cooling, electrical power, and vacuum components is essential. This paper provides an in-depth analysis of the thermal loads of a prototype superconducting wiggler magnet within a three-layer cavity, suspension system, current system, and electron beam chamber, utilizing two cryocoolers.

Speaker: Hui-Huang Chen (National Synchrotron Radiation Research Center)

16:00 Preparing the commissioning of the HL-LHC superconducting magnet circuits: From the inner triplet string to the CERN accelerator complex

The High Luminosity-Large Hadron Collider (HL-LHC) project at CERN aims to increase the integrated luminosity of the Large Hadron Collider by an order of magnitude compared to the LHC original design performance. To achieve this, the existing magnets surrounding the CMS and ATLAS experiments will be replaced with next-generation, high-performance superconducting magnets featuring larger apertures and higher magnetic fields than those currently used in the LHC. These magnets will be powered using a novel superconducting link and state-of-the-art power converters. Upgraded quench detection and protection systems will protect the magnet circuits.
This work provides a comprehensive overview of the HL-LHC magnet circuits and their associated complexities. The commissioning methodology for the HL-LHC magnet circuits is outlined, detailing its validation within the HL-LHC Inner Triplet String test facility, currently under construction, prior to deployment within the CERN accelerator complex. These procedures ensure the reliability and operational readiness of the upgraded systems, paving the way for a successful magnet circuits operation in the HL-LHC era.

Speaker: Samer Yammine (European Organization for Nuclear Research)

16:00 Progress on the design of solenoids for the 6D cooling channel of a muon collider

In the current and most evolved design concept of a muon collider, there exists two long (~1 km) channels for cooling newly created muons and anti-muons. Termed the `6D cooling channels', the beam is cooled in momentum and position space using a series of alternating polarity solenoids, which create an oscillating field in the beam direction, absorbers and radio-frequency cavities. In total there are around 3000 solenoids per channel, contributing to a significant portion of the cost and engineering demands of the entire machine. The integration of the requirements of the field profile with feasible solenoid configurations is a difficult and unique problem, without analytic descriptions to readily relate these. Our approach addresses this problem in two steps: in the first we constrain the beam optics optimization studies by setting engineering limits on solenoid parameters; in the second we have developed a numerical optimization routine to find the best configuration given a desired field profile, in terms of cost and engineering complexity. The following paper reviews this approach and key features,and presents optimization results on the latest optics solution.

Speaker: Siara Fabbri (European Organization for Nuclear Research)

16:00 R&D of 2G-HTS wiggler operated in the cryogen-free system

The National Synchrotron Radiation Research Center (NSRRC) has been at the forefront of advancing synchrotron radiation technologies, including the development of advanced magnet systems. We integrated a wiggler magnet utilizing 2G High Temperature Superconductor (HTS) tape into a cryogen-free system. The wiggler, an essential component for enhancing radiation output, operates effectively within a cryogen-free environment, enabling operational stability and efficiency. The use of 2G-HTS tape significantly improves the magnet's performance, providing a high field strength while reducing thermal load and cryogenic requirements.

Speaker: Pu-Kai Wang (National Synchrotron Radiation Research Center)

16:00 Radiation damage and refurbishment of undulator in SXFEL

Irradiation-induced damage to undulators has become a critical problem in the operation of synchrotron radiation facilities and free-electron laser facilities. During the commissioning and light output phases of the Shanghai Soft X-ray Free Electron Laser facility, the performance of the radiation deteriorated. The main reason for this problem is the impact of high-energy particles on the undulator magnets, which compromised the quality of the magnetic field. This paper examines the radiation damage sustained by the undulators and their refurbishment process.

Speakers: Cheng Yu (Shanghai Synchrotron Radiation Facility), Shudong Zhou (Shanghai Advanced Research Institute)

16:00 Recent progress in the coating and application of Nb3Sn thin film SRF cavity at IMP

Systematic research work including coating process optimization of Nb3Sn thin film on single cell cavity, quality control before and after coating Nb3Sn thin film on multi-cell cavity, and the construction and operation of LHe-free Nb3Sn SRF demo electron accelerator was carried out at IMP. The evolution of Nb3Sn thin films in the whole growth cycle was tracked by experiments, and the mechanism of the oxide layer on the uniform growth of Nb3Sn thin films was clarified by theoretical calculation. Field flatness of the Multi-cell cavity during different post-treatments involving long-distance transport, handling and lifting, light BCP polishing, disassembly, reassembly and coating has been verified. The one-year operation experience of LHe-free Nb3Sn SRF demo electron accelerator will be shared. In addition, the experiment of degradation of wastewater by electron beam irradiation was carried out based on the Nb3Sn SRF electron accelerator.

Speaker: Ziqin Yang (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 RF design for a quadrupole resonator with a fundamental frequency of 325 MHz at IMP

The Quadrupole Resonator (QPR), originally developed at CERN, is a dedicated radio-frequency characterization equipment for evaluating superconducting material. It employs the calorimetric compensation technique and has a surface resistance resolution of less than 1 nOhm, operaing over a wide range of parameters, such as tem-peratures, resonant frequencies and magnetic fields. As a part of R&D work of superconducting material for SRF application in particle accelerators. A QPR with operating frequency of 325 MHz has been developing at Institute of Modern Physics (IMP), CAS. In this paper, we present the detailed electromagnetic design of the QPR, the design focuses on reducing the risk of multipacting, field emis-sion (B_pk/E_pk) and mode overlapping (delta f = f_QPR-f_dipole), enhancing the attainable peak magnetic field (B_sample/B_pk). The electromagnetic simulation results indicate that the optimized structure has good electromagnetic performance. Additionally, the coupler design compatible with four QPR modes will be introduced. The cavity will be fabricated soon.

Speaker: Yong Zhao (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 RF design for optimal high-gradient performance of a four-quadrant structure for the ASTERIX project

The ASTERIX project, funded by CSN5 and proposed at INFN-LNF, aims to demonstrate a practical, meter-long X-band RF structure for linear accelerators made of hard copper and divided into four quadrants. The prototypes will be constructed by TIG welding. In the first year of the feasibility study, we will design the RF cavities for two full structures working at single-bunch and multi-bunch operation. In this paper, structures operating at single-bunch mode for ASTERIX are numerically studied. The surface field enhancements of the quadrant-type accelerating structures are the most challenging issue to be resolved. The geometry near the gap between four quadrants is carefully optimized and obtain low surface field while maintaining high RF performance.

Speaker: Giuseppe Torrisi (Istituto Nazionale di Fisica Nucleare)

16:00 Sensitivity analysis of the 197 MHz prototype crab cavity for EIC

The Electron-Ion Collider at BNL requires several crabbing systems that will be operating at 197 MHz and 394 MHz to compensate for the loss of luminosity due to the large crossing angle of the colliding beams. Two 197 MHz crab cavity cryomodules containing two cavities each will be installed in the Hadron Storage Ring (HSR) at the IP6 interaction region. Due to its large size compared to previously developed crabbing cavities, the 197 MHz crabbing cavity system was identified as one of the critical rf systems in the EIC. Therefore, a cavity has been designed including the ancillaries, and is in the fabrication process, in-house at Jefferson Lab. This cavity will be used to verify the required performance of the first 197 MHz crabbing cavity. Detailed tolerance analysis has been carried out considering cavity operating frequency and HOMs. This paper presents the results from the study in comparison with the achieved tolerances during the fabrication of cavity components.

Speaker: Subashini De Silva (Old Dominion University)

16:00 Status of VPU development for PAL-XFEL

PAL-XFEL is planning to install second hard X-ray undulator line (HX2) to meet the high beamtime demand from the users. The photon energy range for the second hard X-ray beam line is from 2~ to 11 keV which is lower than the first hard X-ray photon energy range (2 ~ 20 keV). The required undulator parameters are 35 mm period, max Keff=3.48 at 9.00 mm gap, ~ 3.0 m magnetic length with phase error less than 5 degrees. In addition to the existing conventional undulator design, horizontal gap vertical polarized undulator (HGVPU) concept is also being considered. HGVPU is well developed by LCLS-II team and applied in LCLS-II. In this report, we summarize the VPU design for PAL-XFEL HX2, and reports progress in the prototyping.

Speaker: YoungGyu Jung (Pohang Accelerator Laboratory)

16:00 Status of elliptically polarized undulator at NSRRC

Since the completion of Taiwan Photon Source (TPS) commissioning in 2015, we have developed and constructed nine APPLE-II undulators of various designs to provide users with soft X-ray sources, particularly for circularly polarized light. To optimize the use of straight-section space, the lengths of the APPLE undulators range from 4.4 to 0.8 meters to accommodate installation constraints. Additionally, an APPLE undulator capable of tapering up to 2 mrad has been developed to meet the spectral demands of broad bandwidth. In pursuit of EPU designs suitable for operation in low-emittance accelerators, we have initiated studies on closed-gap EPUs and constructed as well as experimentally validated a novel insertion device, known as the THU, capable of delivering strong circularly polarized magnetic fields. Moreover, we are also developing a closed-gap type undulator combining electromagnets with permanent magnet structures to generate time-varying magnetic fields, enabling rapid switching of circularly polarized light.

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

16:00 Status of PIP-II HB650 cavities production

STFC is responsible for delivering 20 high-beta 650 MHz cavities for the PIP-II project, with industry partners now producing series cavities. Both pre-series cavities have set world records in performance and cleanliness, meeting the project’s stringent requirement for field emission-free operation, accelerating gradient, and Quality factor. Achieving this milestone required an industrialization of advanced processing techniques, including cold electropolishing and nitrogen doping, and a major effort to optimize cleanroom operations at the vendor’s facility.
We will present the journey from prototyping to industrial production, highlighting the technology transfer, cleanroom upgrades, and QA/QC procedures that enabled these record-breaking results. Early performance data from the first series cavities will also be shared, demonstrating progress toward full-scale production.

Speaker: Anna Shabalina (Science and Technology Facilities Council)

16:00 Status of the RF system design for the SC240 cyclotron

The superconducting cyclotron SC240 is used to accelerate proton beams to 240 MeV for proton therapy. The SC240 is an isochronous 4 sectors compact cyclotron with a central magnetic field of 2.5 T. Particles acceleration is performed under the second harmonic mode of the radio-frequency (RF) system, consisting of two independent cavities located in the cyclotron valleys. Block on the chimney is designed to avoid interference between two cavities. The isolation (S21) is less than -30dB. In cavities, two types of tuners applied to compensate for frequency offset are tuning loop and trimmer plate. The tuning frequency range of tuning loop is more than 1MHz, that can be used to adjust the frequency offset caused by machining error and installation error during cold test, rather than caused by thermal deformation when feeding high power into cavities, While the trimmer plate is just used in the opposite way. Efficiency of acceleration voltage in center region caused by different ground position of ion source is presented in the paper. Design and optimization of inductive coupler are described in details. Besides, the current operating status of the RF system will also be discussed.

Speaker: Gen Chen (Institute of Plasma Physics)

16:00 Stripline kicker design for FCC-ee booster injection and damping ring

The FCC-ee booster injection kicker, will be injecting 4 particles bunches per single kick. The bunch separation in the booster ring is 25 ns and therefore requiring a faster kicker rise and fall time to not perturb injected or already circulating bunches. The wakefield impedance of the stripline is also important to not perturb the stored beam as well as it is necessary to ensure a good integrated fields and field homogeneity for kicking the bunches. The major challenge is to provide a precise impedance matching along the entire path of the electric pulse from the generator to the stripline termination. Transmission line cables, connectors and feedthroughs may already distort the pulse. 3D model of the stripline magnet including the high voltage connectors and simulation model of cables and generator was designed. It is shown that the results of the stripline magnet simulations meets the requirements, but the design of the entire system will need to be supplemented by research into active compensation for cable pulse distortion. The results are discussed in terms of validity due to assumed component parameters and ideas for benchmarking on a laboratory prototype are outlined.

Speaker: Konstantinos Papastergiou (European Organization for Nuclear Research)

16:00 Study of a fast kicker magnet for beam scanning in VHEE therapy

Over the past two decades, very high-energy electron (VHEE) beams ranging from 50 to 250 MeV have been explored as a potential technology for treating deep-seated tumors. FLASH radiation therapy (FLASH-RT) delivers ultra-high dose rates (UHDR) within a few milliseconds, suggests the possibility of enhanced cancer cell lethality while reducing damage to normal tissues. Combining VHEE with FLASH-RT shows potential in cancer treatment.
Pencil beam scanning (PBS) is an important technique in VHEE radiotherapy. However, the ultra-short treatment times required by FLASH-RT (0.1–1 second) imply that the scanning speed must be very high, necessitating linear accelerators (LINACs) with a repetition rate significantly higher than 1 kHz, which is challenging to achieve. A fast kicker magnet, consisting of a one-turn coil and a pulsed power supply, can generate a magnetic field with rapid rise and fall times. A LINAC can produce an electron beam with a variable bunch train of 0.1-1 μs. By deflecting the bunch train using a fast kicker magnet, it is possible to generate a line scan that approximates the functionality of pencil beam scanning.

Speaker: Kuang-Lung Tsai (National Synchrotron Radiation Research Center)

16:00 Superconducting β=0.19 half-wave cavity for CiADS

A 162.5 MHz, optimal beta = 0.19 pure niobium half-wave resonator (HWR) called HWR019 for the superconducting driver linac of the China initiative Accelerator-Driven subcritical System (CiADS) has been designed and analyzed at the Institute of Modern Physics, Chinese Academy of Sciences (IMP, CAS). The linac requires 24 HWR019s to accelerate protons from 6.8 MeV to 45 MeV. This paper mainly presents a design scheme of HWR019. Meanwhile, electromagnetic field optimization, and mechanical structure design are carried out, to predict the behavior of the cavity under practical operating process. At present, this superconducting cavity has been fabricated a prototype and awaits further testing.

Speaker: Mr Zehua Liang (Institute of Modern Physics, University of Chinese Academy of Sciences)

16:00 Test coil-unit fabrication of Nb3Sn superconducting multipole wiggler for next generation light source in KEK-PF

Recently, KEK PF has started developing a superconducting multipole wiggler (SC-MPW) for an application in next-generation light source ring. The SC-MPW is expected to be a key insertion device for the light utilization of a wide wavelength region by aiming at high-brightness and high-energy X-ray production while keeping the stored beam energy as low as 2.5 GeV. In addition, the short period length of multipole wiggler not only lowers the light spread and increases the effective photon flux, but also reduces the beam orbit amplitude, which leads to suppressing the emittance growth in a low emittance ring. In our application, the magnetic field more than 2.5 T is required on the central beam orbit even in a short period length less than 80 mm with a wide gap more than 30 mm that secures the beam orbit region. As we need to investigate the candidate of Nb3Sn wires and to study the coil-fabrication techniques which meet a use as multipole wiggler, PF has completed the first prototype-coil unit consisting of three poles and successfully conducted excitation tests at the low current. The detailed fabrication of test-coil unit and the prospects for high-current testing will be reported.

Speaker: Chikaori Mitsuda (High Energy Accelerator Research Organization)

16:00 Testing and characterization of surface treatment techniques for enhancing the HV performance of kickers

Accelerator kicker magnets, which commonly use ferrite and other insulating materials, can encounter High Voltage (HV) performance limitations due to interactions with the particle beam. These interactions, can lead to electron cloud buildup and charging phenomena on exposed surfaces, negatively impacting kicker performance, particularly at high beam intensities. To mitigate these effects, surface treatment techniques are investigated to improve the HV kicker performance under such conditions.
A dedicated set-up is under development to perform HV testing of treated surfaces in both ambient and in vacuum conditions, closely simulating operational conditions. This paper presents insights into the effects of these surface treatments on material properties, supporting strategies to enhance HV kicker reliability at higher beam intensities.

Speaker: Konstantinos Papastergiou (European Organization for Nuclear Research)

16:00 The Canted Cosine Theta HTS sextupole demonstrator of FCC-ee

A single-aperture two-layer Canted-Cosine-Theta (CCT) sextupole magnet using as conductor high-temperature superconducting (HTS) ReBCO tape has been developed for the short straight sections (SSS) of the FCC-ee study. Manufacturing details, including paraffin wax impregnation and cryogenic temperature measurements, are presented. This demonstrator represents the first CCT magnet constructed from HTS tape.

Speaker: Michael Koratzinos (European Organization for Nuclear Research)

16:00 The cavity combiner development for TPS SSPA tower at NSRRC

NSRRC builds four home-made solid state power amplifier towers to provide 300 kW for one superconducting RF cavity at TPS. The power combining tree of one tower is two-stages structure with a complex wire connection. In order to simplify the wire connection and increase the power combining efficiency, we devote resources to develop the cavity combiner. In this study, a 21-ports cavity combiner is designed and manufactured. The RF properties, S11 and S21, of output port were simulated and measured to evaluate the combining efficiency.

Speaker: Shian Wen Chang (National Synchrotron Radiation Research Center)

16:00 The impact of insertion devices on Solaris storage ring optics

This study investigates the influence of insertion devices (IDs) on the optical properties of the Solaris electron storage ring through a combination of experimental measurements and simulations. The effects of various ID settings were analyzed using tune measurements and the Linear Optics from Closed Orbits (LOCO) method. These results were compared with simulations performed using the Python Accelerator Toolbox (pyAT). Furthermore, a Long Short-Term Memory (LSTM) neural network was developed and tested for forecasting corrector magnet currents associated with the IDs. Diagnostics included monitoring the electron beam in the storage ring and photons delivered to beamlines. Additionally, the performance of both slow and fast orbit correction systems in response to ID-induced perturbations was assessed. This work provides insights into ID impact on beam dynamics and highlights the potential of machine learning for predictive control in accelerator systems.

Speaker: Roman Panas (SOLARIS National Synchrotron Radiation Centre)

16:00 The study of the eddy current-type septum magnet for fast extraction in J-PARC MR

The eddy current type septum magnets (Eddy-septa) are used for fast extraction in J-PARC MR from 2022. Currently, the operation of the Eddy-septa is very stable. However, we have some still technical issue. One is an output pulsed current measurement by current transfers. The peak value of the output pulsed current is measured pulse by pulse and the measured value is used for a feedback system using by PXI system for long-term stability. The output current is also measured with different current transfer in same time for double checking. However, we don't have good reproducibility with the measurement result by the PXI feedback system yet. We have found the noise which are generated by the kicker magnets and extraction beam in 2023, thus, we started to investigate the detail of the process of generation and method of removal. Second is residual field along the circulating beam line in Eddy-septa. We had reported the leakage field by exciting current on the circulating beam line and the strength was very small. In summer of 2023, we found large residual field on the same line. In this presentation, we report the status of measurement of output current, and residual field.

Speaker: Tatsunobu Shibata (High Energy Accelerator Research Organization)

16:00 Thermal analysis for the fundamental power coupler of the 197 MHz crab cavity for EIC

The Electron-Ion Collider (EIC) is being designed by BNL in collaboration with Jefferson Lab. The Phase-I design includes the installation of two cryomodules of 197 MHz crabbing cavities installed at the Hadron Storage Ring (HSR) at the interaction region, IP6 that has a crossing angle of 25 mrad. Each cryomodule consists of two 197 MHz RFD type crabbing cavities. The first article cavity has been designed following the machine requirements and specifications including the fundamental power coupler (FPC), higher order mode couplers, and field probes. A detailed rf analysis has been completed to determine the worst operational case of the FPC. Next, the thermal analysis was carried out to design the warm-to-cold section of the FPC. This paper presents the detailed rf and thermal analysis of the 197 MHz first article crabbing cavity.

Speaker: Subashini De Silva (Old Dominion University)

16:00 Third order resonance correction using new Trim-S system in J-PARC MR

In the Japan Proton Accelerator Research Complex (J-PARC) Main Ring (MR), to address the issue of resonance correction for third-order resonances in both on- and off-momentum particles, an upgrade project utilizing 24 Trim-S units has been proposed based on numerical simulations. As a first step in verifying its effectiveness, four additional Trim-S (new Trim-S) power supplies, configured with a System-on-Chip (SoC) Field Programmable Gate Array (FPGA) controller, have been installed. The performance of the new system was experimentally verified by correcting the resonance using these 4 new Trim-S units. Beam loss was successfully reduced compared to that with the original Trim-S system, demonstrating the effectiveness of the new system.

Speaker: Yulian Tan (High Energy Accelerator Research Organization)

16:00 Transient finite-element simulations of fast-ramping normal-conducting magnets for a 10 TeV muon collider

Ongoing conceptual studies for a 10TeV muon collider identified rapid cycling synchrotrons as major engineering challenge. Due to the muon’s short lifetime of only 2.2µs at rest, normal-conducting bending magnets with field rise rates of well beyond 1kT/s are indispensable to support accordingly fast acceleration cycles. Energies of 100MJ will be interchanged between magnets and capacitor banks within few milliseconds. Accurate models of the magnets are thus required to optimize the overall system performance. The non-uniform temperature distribution in the magnet strongly affects material properties like the electrical conductivity of copper and must therefore be considered in the electromagnetic field problem. This contribution presents recent advancements in addressing this multi-physical problem by using problem-specific finite-element tools allowing to describe the inherently transient behavior. The ferromagnetic yoke is accurately resolved by using a novel combination of a Bergqvist hysteresis and a homogenized eddy current model. Finally, different magnet design concepts are compared in terms of material costs, magnetic energy, losses, field quality and temperature buildup.

Speaker: Dominik Moll (Technical University of Darmstadt)

16:00 Transitional solution of solid-state power amplifier at NSRRC

The Taiwan Photon Source (TPS) of the National Synchrotron Radiation Research Center (NSRRC) in Taiwan has integrated Solid-State Power Amplifiers (SSPAs) into routine operations since 2023, supporting a stored beam current of 500 mA. In response to the phasing out of Ampleon's BLF578 and the growing demand for improved energy efficiency, a new SSPA was developed based on the existing module configuration, utilizing the BLF978P as an interim solution. This approach serves as a bridge while the development of the next-generation SSPA, employing GaN transistors, is still underway. Both SSPA configurations, with and without circulators, were explored during development. This paper presents the performance of the prototypes and the implementation details.

Speaker: Chao-Hui Huang (National Synchrotron Radiation Research Center)

16:00 Upgrade of low-level RF system for J-PARC linac RFQ-TS

The radio-frequency quadrupole test stand (RFQ-TS) was prepared for conditioning the spare RFQ in the J-PARC Linac. Additionally, the RFQ-TS is used for the development of accelerator components and the acquisition of beam parameters. The digital feedback system of the Low-Level RF (LLRF) in the RFQ-TS was previously using the discontinued cPCI system, which had been in use for 20 years since its development. In order to continue improvements of the RFQ-TS and to allow for future development, the system has been upgraded to use $\mu$TCA.4-based system, which can be developed further. In this presentation, we will report the details of the upgrade, as well as the feedback and feedforward adjustments.

Speaker: Hideto Nakano (Japan Atomic Energy Agency)

16:00 Upgrade of the insertion device measurement benches and associated software at the ESRF

The European Synchrotron Radiation Facility (ESRF) has built and characterized many insertion devices and magnets over the past decades. The magnetic measurements rely on dedicated benches, based on stretched wire for integral measurements and on hall probes for local measurements. A major upgrade of these benches is being developed. It includes new features such as coordinate measurents, upgraded acquisition boards and hall probes, and a new control software based on Python, HDF5 data format and Qt. The B2E software, used for computing synchrotron radiation and for shimming undulators, was completely refactored. This paper presents the architecture of these new benches, the status of the project and the first results.

Speaker: Gaël Le Bec (European Synchrotron Radiation Facility)

16:00 Upgrade of the kicker pulser based on LC resonanr circuit

LC resonant circuit is widely used in all kinds of pulse power supply because of its simple structure and reliable performance. Among them, the scheme with thyratron as the main power device has been verified for a long time in the BEPCII injection system. With the continuous improvement of the technical requirements of all kinds of accelerators, the performance of the pulser has become critical. In order to obtain the pulse signal with higher voltage and shorter bottom width, it is necessary to upgrade the equipment. This paper aims to introduce a new type of the pulser topology to meet the needs of the injection and extraction system for BEPCII-U and HEPS.

Speaker: Guanwen Wang (Institute of High Energy Physics)

16:00 → 18:00 Wednesday Poster Session: WEPM

16:00 3Qy resonance correction at LHC injection

Compensation of the 3Qy resonance at injection energy in the LHC is of significant interest, given its potential to degrade the lifetime of high-intensity beams. In the absence of dedicated corrector circuits for the 3Qy compensation of each beam at low energy, an alternative approach is needed. Using skew-sextupoles in the four common experimental insertions it has been possible to develop a scheme to independently control the 3Qy resonance of the two LHC beams. Beam-based measurements and corrections of the 3Qy resonance at injection were performed, with beneficial impacts on lifetime and emittance growth observed.

Speaker: Ewen Maclean (European Organization for Nuclear Research)

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)

16:00 A particle-in-cell implementation of intra-beam scattering for Xsuite

Intra-Beam Scattering (IBS) remains one of the primary mechanisms of emittance blow-up and performance degradation in the Large Hadron Collider (LHC) accelerator chain. The phenomenon is particularly relevant following the recent injector upgrades to achieve the high-brightness beams required for the High Luminosity LHC (HL-LHC) era. Traditional IBS models, as those already implemented in Xsuite, rely on the assumption of Gaussian beam distributions. However, observations in the CERN complex indicate the presence of q-Gaussian beam profiles, for which these models do not accurately reproduce IBS effects. To address this limitation, a Particle-In-Cell (PIC) approach was developed that operates independently of distribution assumptions. This methodology behind the PIC approach, and benchmarks against existing models as well as experimental data from the LHC are presented in this contribution. Current limitations are also discussed.

Speaker: Felix Soubelet (European Organization for Nuclear Research)

16:00 Advances in machine learning inference of dynamic aperture evaluation for the LHC

Dynamic aperture (DA) is a crucial metric for understanding nonlinear beam dynamics and particle stability in circular accelerators like the Large Hadron Collider (LHC) and its future High-Luminosity LHC (HL-LHC) upgrade. Traditional methods for DA evaluation are computationally intensive, requiring extensive tracking of large particle ensembles over many turns. Recent advances in machine learning (ML) have shown that models, particularly architectures like Bidirectional Encoder Representations from Transformers (BERT), can significantly accelerate DA predictions while achieving accuracies comparable to traditional simulations. Enhanced uncertainty quantification techniques further improve model reliability, providing a foundation for robust active learning frameworks. This work presents the latest progress in DA inference, focusing on architectural advances, data preparation, and optimised training techniques. Applied to LHC tracking data, these improvements highlight the importance of high-quality data generation and customised training strategies for enhancing model performance and uncertainty management, paving the way for future HL-LHC studies.

Speaker: Carlo Emilio Montanari (University of Manchester)

16:00 Alignment tolerance studies for the cSTART storage ring

The KIT cSTART project (compact STorage ring for Accelerator Research and Technology) aims to demonstrate the injection and storage of a high intensity ultra-short electron bunch in a large acceptance storage ring using the FLUTE linac and a laser plasma accelerator (LPA) as injectors. Amongst the unique features of the cSTART project is the wide dynamic range of machine and beam parameters to be employed, i.e. bunch charge, bunch length, beam energy, etc. The comparably low energy beam (40-90 MeV) will be injected on-axis and will be stored for about 100 ms without reaching equilibrium due to the absence of significant radiation damping. In order to ensure stable operation of the storage ring, we need to specify tolerable magnetic lattice misalignments and understand the impact on the beam dynamics to be able to implement adequate correction schemes.
In this paper, we report on first studies and simulation results on the effects of magnet misalignment, roll angles, and field errors on the dynamic aperture and momentum acceptance of the cSTART storage ring and propose a suitable correction strategy.

Speaker: Patrick Schreiber (Karlsruhe Institute of Technology)

16:00 Analysis of losses and emittance growth in the 2024 LHC run and correlation with Dynamic Aperture

This paper presents observations collected during the LHC operation with proton beams in 2024. In particular, a systematic analysis of the beam and machine parameters along the run reveals that the emittance evolution at the LHC injection plateau and during collisions cannot be fully explained by Intra-Beam scattering, synchrotron radiation and electron cloud effects, thus indicating that some beam dynamics effects are missing in the models. During the collapse of the separation bumps, a significant drop in beam lifetime is observed due to the reduction of Dynamic Aperture as the separation reduces and the machine enters into a beam-beam dominated regime. The correlation of beam lifetime in operation and Dynamic Aperture in simulations is demonstrated. Furthermore, a strong correlation is identified between this lifetime reduction and the population of non-Gaussian tails in the transverse beam profiles. The paper also includes the observation of high-frequency power supply ripple in the beam spectrum.

Speaker: Sofia Kostoglou (European Organization for Nuclear Research)

16:00 Analysis of resonance lines and working points of the HALF storage ring lattice

The Hefei Advanced Light Facility (HALF) storage ring employs a hybrid six-bend achromat lattice with long and short straight sections. In this paper, main resonance lines of on- and off-momentum dynamic apertures (DAs) of the HALF lattice are analyzed by using frequency map analysis and considering $\beta$-beat. The combined effect of a fifth-order structural resonance and a half-integer non-structural resonance can induce notable particle loss in off-momentum DAs over a certain range of negative energy deviations. However, it has a limited impact on local momentum aperture even with relatively large $\beta$-beat. Using the analysis of resonance driving term fluctuations, the HALF lattice with a new working point is studied, which exhibits a significantly improved 6D DA in the direction of beam injection.

Speaker: Masahito Hosaka (University of Science and Technology of China)

16:00 Analytic theory of the skew wake effect

In the present study we provide a simple model and a physics insight into the recently discovered Skew Wakefield Effect*. We show that the effect posses certain complexity as along with the rotation of the principle axis of the quadrupole wake there exist an overall increase in the wake transverse wake amplitude.

Speaker: Stanislav Baturin (ITMO University)

16:00 Beam coupling impedance wireless measurements and application to HL-LHC accelerator components

A novel wireless method for beam coupling impedance measurements is currently under development, with preliminary measurements on beam pipes serving as proof of concept for its validity. This innovative approach overcomes the limitations of existing methods by not only evaluating impedance with high accuracy but also enabling the characterization of an unknown Device Under Test (DUT) as it will be installed in the accelerator. This capability is crucial for constructing accurate impedance models of accelerators and may help resolve or reduce discrepancies between modelled and measured impedance contributions. While analytical computations or simulations can provide accurate predictions of the beam coupling impedance for simple beam pipes with well-defined material properties, they often fail to account for real-world imperfections, such as surface roughness. Potential applications of this method are the characterization of High-Luminosity LHC collimators and other beam vacuum components planned for future installation. By providing detailed insights into their impedance contribution, this method could play a pivotal role in achieving a highly accurate HL-LHC impedance model.

Speaker: Chiara Antuono (European Organization for Nuclear Research)

16:00 Beam dynamics studies and optimization for a compact Cband LINAC for FLASH radiotherapy

Developing medical accelerators for clinical use presents significant challenges, particularly for FLASH radiotherapy, where specific beam parameters are essential to activate the FLASH effect. At Sapienza University, a new electron FLASH LINAC is being developed, designed to deliver FLASH electrons and adaptable for very high-energy electron (VHEE) applications. This work focuses on overcoming the inherent challenges of FLASH radiotherapy: achieving high energy gain in RF structures while transporting high-current electron beams within a compact, cost-effective accelerator. These goals are often at odds, as the high peak currents required for the FLASH effect introduce beam loading, reducing energy gain. Through extensive simulations and optimizations, the accelerator design has been refined, with key improvements in the power supply, RF cavities, and source configuration. This study marks a crucial step toward the realization of compact, scalable, and efficient accelerators for advanced radiotherapy, offering innovative solutions for future medical treatments.

Speaker: Stefano Farina (Sapienza University of Rome)

16:00 Beam impedance investigation of the elliptical interconnecting vacuum modules of the LHC and prospect for HL-LHC

In view of ensuring the successful completion of the third operational run of the Large Hadron Collider (LHC) and preparing for the High-Luminosity LHC era, a systematic assessment of the risk of failure of all the vacuum interconnection modules installed in the accelerator is being carried out. This was prompted by a significant pressure rise in 2023, localized near an interconnection module (212 mm inner diameter) caused by a localized impedance-induced heating on the tension spring. This led to degradation and loss of electrical contact of the Radiofrequency (RF) sliding fingers. The studies include the evaluation of the various modules currently present in the LHC, alongside the description of a mitigation strategy. In this paper, we focus on the study of elliptical vacuum modules both from the point of view of electromagnetic simulations and of experimental validation. We report also on the general strategy where the most critical vacuum modules with sliding contact RF fingers, featuring tension springs, will be replaced with upgraded designs to avoid issues and therefore ensure improved reliability under future operational conditions with higher bunch intensities.

Speaker: Chiara Antuono (European Organization for Nuclear Research)

16:00 Beam instability suppression during debunching process through slippage factor tuning in the J-PARC Main Ring

The J-PARC Main Ring achieves a high extraction efficiency of 99.5% during 30 GeV slow extraction at the current beam power of 80 kW. However, at beam powers above 30 kW, we observed ring-wide beam losses due to transverse beam instability associated with vacuum pressure rises and electron cloud effects, which are believed to be triggered by longitudinal microwave structures. To achieve stable operation at 80 kW, we implemented phase offset injection into RF buckets and two-step RF voltage reduction during debunching. For planned higher-power operations, we propose tuning the slippage factor to suppress the microwave structures during debunching. The Main Ring features a unique imaginary transition gamma lattice, and we discovered that the slippage factor can be adjusted using appropriate combinations of four quadrupole families in the arc sections while maintaining the operating tune and achromatic conditions in the long straight sections. Such slippage manipulation would be impossible in a ring with a conventional FODO lattice. The slippage factor can be ramped from its nominal value to a suppressing value during acceleration.

Speaker: Ryotaro Muto (High Energy Accelerator Research Organization)

16:00 Beam loss simulations for space charge mitigation in J-PARC MR

The main ring synchrotron (MR) of the Japan Proton Accelerator Research Complex (J-PARC) provides high power proton beams to neutrino and hadron experiments. Since we are planning to increase the beam intensity from current $2.3 \times 10^{14}~$protons per pulse (ppp) to $3.3 \times 10^{14}~$ppp, we need to reduce the beam loss. In the J-PARC MR, the space charge is one of the main causes of beam loss. As a first step, we developed a new beam optics suppressing the space-charge-induced resonance which is the primary cause of the beam loss. In this paper, we report details of the beam loss mechanism in J-PARC MR by comparing the tune scan results of the present and new beam optics.

Speaker: Takaaki Yasui (High Energy Accelerator Research Organization)

16:00 Beam optics model and characterization for CERN's low-energy ISOLDE transfer lines

The PUMA (antiProton Unstable Matter Annihilation) experiment at CERN aims to explore the interaction of antimatter with exotic isotopes, utilizing the unique capabilities of CERN’s ISOLDE facility and Antiproton Decelerator. This contribution presents recent advancements in the beam transfer lines optics studies relevant to the success of the experiment, and to ISOLDE’s operation in general. A detailed beamline model has been developed using MAD-X and XSUITE, including the consideration of apertures and alignment errors. Quadrupole scans and kick response measurements have been employed to build and benchmark the model. In addition, tomographic reconstruction was tested, aiming to obtain a detailed characterisation of the beam's transverse phase space. A distinctive feature of ISOLDE’s beamlines is the use of electrostatic, rather than magnetic, quadrupoles. To address this, an electrostatic quadrupole model was developed and benchmarked using CST. These promising results validate the optics model, demonstrating its potential to improve beam delivery across the Low-Energy ISOLDE facility and contributing towards the PUMA experiment's operational readiness.

16:00 Beam optics simulations of achromatic section of Delhi Light Source

The Delhi Light Source is an upcoming user facility for coherent THz radiation and electron beam. Electron beam of energy upto 8 MeV generated from a RF photo-cathode gun will be used for coherent THz generation from a planer undulator. The beam after passing through the undulator field will be separated from the THz and THz line by a $60^{o}$ achromatic section and delivered to electron experimental area. Simulation studies has been performed to achieve achromatic condition and acceptable beam size at the electron experimental area for the case of electron transmission through non-trivial undulator field. However for the case of open gap undulator (no THz generation), the study shows that the same design gives a limited control on the overall beam size at the electron experimental area. To overcome this the extended quadrupole correction (EQC) coils of the undulator can be used as a suitable focussing element to achieve required beam size control in addition to the achromatic condition. The paper presents the simulation studies of the achromatic section for both with and without(open gap) undulator field.

Speaker: Joydeep Karmakar (Guru Ghasidas Vishwavidyalaya)

16:00 Beam-based beam-beam benchmarking and correction

Optics studies in the LHC are generally performed on low-intensity, non-colliding beams. Understanding the optics perturbation from beam-beam effects however, is of significant interest. This was particularly true for the LHC in 2024, where the 3Qy resonance driven by the long-range beam-beam (LRBB) contributed to breaking of the collimator hierarchy, limiting beta* reach and luminosity. By performing optics measurements on a low-intensity bunch in collision with a nominal train, it has been possible for the first time to directly measure the optics perturbation from LRBB in the LHC. Benchmarking of the beta-beat and resonance driving terms against simulation shows good agreement. Based on these models, it was possible to find corrections for the LRBB driven 3Qy resonance using the skew-sextupole correctors present in the LHC.

Speaker: Ewen Maclean (European Organization for Nuclear Research)

16:00 Beam-based characterization of longitudinal coupled-bunch instabilities at SIRIUS storage ring

SIRIUS is the 4th generation synchrotron light source of the Brazilian Synchrotron Light Laboratory (LNLS). In mid 2024 the storage ring had a major upgrade on the rf system, with the replacement of the PETRA 7-Cell rf cavity by two superconducting (SC) CESR-B cavities. It was antecipated that after the upgrade the longitudinal coupled-bunch instabilities (LCBIs), previously driven by the higher-order-modes (HOMs) of the PETRA 7-Cell cavity, would not longer occur. However, different LCBIs were observed at currents as low as 90mA. In this work, we report on the experimental methods and results to characterize these LCBIs through beam-based measurements using the bunch-by-bunch feedback system. We also present simulations to evaluate the expected impact of the harmonic cavity planned for the next operational phase.

Speaker: Otávio Silveira (Brazilian Synchrotron Light Laboratory)

16:00 Benchmarking of LHC beam intensity dependent transverse tune corrections at injection energy

Observations of betatron tune evolution during LHC beam injection have revealed a significant tune error, strongly correlated with beam intensity. This finding highlights limitations in the existing feedforward corrections based on Laslett coefficients. A dedicated machine development study was conducted to refine intensity-dependent tune corrections. Utilizing high-precision, per-bunch tune measurements facilitated by the LHC transverse feedback system, the study characterized tune shifts under varying intensities and beam conditions. The results uncovered pronounced discrepancies between horizontal and vertical planes, which deviate from predictions made by the current correction model. These insights provide a critical foundation for improving the accuracy of intensity-dependent tune adjustments, impacting operational stability and efficiency, in particular when considering future operation of the high-luminosity LHC.

Speaker: Joanna Wanczyk (European Organization for Nuclear Research)

16:00 BESSY III intra-beam scattering and touschek lifetime calculations

The 4th generation synchrotron light source, BESSY III, is expected to enable high-impact applications for users in life science, material science, energy and catalysis materials, and more. Currently in its Conceptual Design Report (CDR) phase, the feasibility of BESSY III's ambitious parameter range necessitates a thorough assessment of "collective effects". These phenomena can either compromise beam stability or degrade beam quality, potentially hindering the expected performance. In this work, we present recent estimations of the Intra Beam Scattering (IBS) and Touschek lifetime for the BESSY III lattice. The IBS leads to an increase in longitudinal and transverse emittances, it is described through the IBS growth rates and equilibrium emittances. Both quantities were computed with the ibsEmittance module from elegant and a newly implemented module in Xsuite. The Touschek effect induces beam losses along the storage ring resulting in a shorter beam lifetime. Its effect was computed using pyAT. Finally, the impact of different emittance coupling factors is studied to mitigate both effects, laying the first stone for future studies with higher-harmonic cavities.

Speaker: Sébastien Joly (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 BESSY III orbit correction scheme layout and performance

Currently in its Conceptual Design Phase (CDR), the 4th generation light source BESSY III aims to become a world-leading soft X-ray source, enabling numerous applications in metrology, life sciences, energy and catalysis materials, and many more. Its performance relies on ultra-low transverse emittances, achieved through the use of strong focusing magnetic elements that are sensitive to magnetic and alignment errors. If left uncorrected, these errors give rise to a distortion of the closed orbit, beta beating, linear coupling, and a stronger impact of resonances thus impairing the storage ring performance. In this work, we address how to devise an initial BESSY III orbit correction scheme. Two criteria were considered to find the optimal locations of Beam Position Monitor (BPM) and dipolar Corrector Magnet (CM). Different orbit correction scheme candidates are presented and their advantages and disadvantages are discussed. All calculations were performed in parallel with the Matlab toolkit Simulated Commissioning (SC) and its Python counterpart (pySC).

Speaker: Sébastien Joly (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 Broadband characterization of the CERN-SPS driving and detuning impedance

The CERN-SPS transverse impedance model plays an important role in predicting beam stability and guiding machine operation. This work advances the benchmarking of the SPS vertical impedance model through experimental investigations of mode-zero instability growth rates and intensity-dependent tune shifts as a function of chromaticity. Building on insights from previous measurement campaigns, this study aims to address persistent discrepancies in the high-frequency domain associated with the real driving component of the effective impedance. The 2024 campaign incorporates growth rate measurements at varied transverse tunes to eliminate potential resonance crossing effects that could artificially enhance the high-frequency mismatch. The imaginary component of the transverse impedance is likewise explored by correlating intensity-dependent tune shifts with chromaticity variations. By combining all measurements and beam dynamics simulation results, the driving and detuning impedance model of key elements will be refined, offering improved predictive capabilities for the current SPS transverse impedance model.

Speaker: Elena de la Fuente (European Organization for Nuclear Research)

16:00 Bunch lengthening of the SSMB storage ring

Study of bunch lengthening effect in SSMB storage ring using STABLE program.

Speaker: Weihong Huang (Tsinghua University)

16:00 Can we obtain relativistic vortex electrons using linacs?

Relativistic vortex electrons carrying orbital angular momentum (OAM) may provide a novel tool for applications in atomic, nuclear, and particle physics. A straightforward approach to produce such particles involves generating vortex electrons using conventional methods, such as fork-like holograms or magnetic monopoles, followed by their acceleration in a linac. While the azimuthal symmetry of the linac's electric and magnetic fields preserves the electron's OAM, the potential transfer of OAM to emitted photons raises a fundamental question: Can vortex electrons be effectively accelerated in linacs, or do they lose their OAM in the process?
To address this question, we construct localized wave-packet vortex solutions to the Klein-Gordon equation in the presence of longitudinal electric and magnetic fields. The probability of photon emission by these states is calculated in the first order of perturbation theory. We estimate the rate of OAM loss and the characteristic acceleration length over which the electron's vorticity is lost, using parameters relevant to typical linac setups.

Speaker: Georgii Sizykh (ITMO University)

16:00 Cavity loops Influence on the single-bunch Instability thresholds of the CERN PS Booster

The CERN Proton Synchrotron Booster (PSB) delivers a wide variety of high-intensity and high-brightness proton beams to several destinations, including operations at the Large Hadron Collider (LHC) and various fixed-target experiments. Following the Long Shutdown 2 (LS2) upgrades, discrepancies between beam measurements and macro-particle simulations were observed, highlighting the need for a deeper understanding of the longitudinal impedance and related effects in the PSB. To address this, longitudinal single-bunch instability studies have been conducted to evaluate the impedance model through the intensity and energy thresholds across different radio-frequency configurations. This contribution presents experimental results that explore instability mechanisms and the effect of the beam loading compensation feedback system. These results are used to benchmark a new cavity loop simulation, which enables more detailed studies of the accelerator impedance.

Speaker: Mariangela Marchi (Sapienza University of Rome)

16:00 Characterization of beam optics considering fringe fields of quadrupole magnets in a LIPAc 5 MeV beamline

The 5 MeV beamline of Phase B+ which is an intermediate commissioning stage of the Linear IFMIF Prototype Accelerator (LIPAc) consists of an MEBT, an MEBT Extension Line (MEL) where the SRF will be installed, a HEBT, and a beam dump. It has 17 quadrupole magnets, and some quads have small aperture-to-length ratios and are also densely installed in the MEBT and HEBT sections. In the early stages of Phase B+, we optimized the beam optics with the conventional hard-edge model for all the quads. However, we observed unwanted particle losses and discrepancies in the rms beam sizes between measurements and simulations due to significant fringe fields and magnetic interference. After considering the field maps and the magnetic interference of the quads in the beam optics, we could obtain the matching beam and reduce the particle losses. In this paper, we characterize the beam optics by comparing the transfer matrices with and without the fringe fields and the interferences using a conventional hard-edge model and a more accurate hard-edge model equivalent to the field maps.

Speaker: Jibong Hyun (National Institutes for Quantum Science and Technology)

16:00 Computational analysis of shielding on the coherent synchrotron radiation generated by a 3D bunch

The analysis and mitigation of collective beam effects, such as coherent synchrotron radiation (CSR), is a significant challenge in the generation of high-brightness beams. To this end, considerable effort has been invested in the development of simulation tools to accurately characterize the CSR generated by a bunch following a curved trajectory. In particular, with codes like LW3D and CoSyR, it is possible to model the CSR wake due to an evolving 3D bunch distribution in free space with minimal approximation. Recently, we have developed a simulation tool that self-consistently characterizes CSR through direct computation of the Liénard–Wiechert fields while accounting for the presence of shielding walls. In this work, we use this method to study the CSR shielding effect on a complex bunch moving through both a single dipole and a bunch compressor, with particular emphasis on the boundaries of validity of 1D theory in predicting the phase space evolution. This work is part of a broad effort to investigate the impact of shielding both theoretically and through a series of planned experiments at the Argonne Wakefield Accelerator (AWA).

Speaker: Xueying Lu (Northern Illinois University)

16:00 Current status of beam dynamics study for RAON high energy linear accelerator (SCL2)

In 2023 the beam commissioning of low energy superconducting linear accelerator (SCL3) of a heavy ion accelerator, RAON have been finished in Daejeon, Korea by Institute for Rare Isotope Science (IRIS) in Institute of Basic Science (IBS). The purpose of this accelerator is the generation of rare isotope by ISOL (Isotope Separation On-Line) and its acceleration for the nuclear physics experiment. Also, the accelerator operation for first user service using SCL3 section has been performed in 2024. Nowadays a project to develop and construct the high energy superconducting linear accelerator are being ongoing. This section is planned to use two kinds of superconducting cavities. They are all single-spoke-resonator type cavities while the optimum beam betas($\beta_{opt}$=0.32 and 0.51) are different. Due to the diversity of planned ions and isotopes, the research related with lattice design and beam dynamics optimization is one of the important for this project. In this presentation summary of linear accelerator lattice design and beam dynamics simulation results will be described.

Speaker: Hyojae Jang (Institute for Basic Science)

16:00 Data driven methods to recognize patterns in EIC weak-strong simulation

Beam-Beam simulations are currently being studied in preparation for future EIC experiments to study beam-beam effects and, in turn, maximize luminosity. Weak-strong methods are studied for single-particle dynamics during collision. 1 million macro-particles for 1 million turns are typically tracked, corresponding to only 10 seconds in the EIC. The goal of this study is to predict beam properties over the scale of hours. A potential solution focuses on using data-driven methods such as machine learning methods to analyze and extend the insights of the beam properties such as long-term nonlinear effects. This would aid in long-term predictions where results would be more efficiently acquired than a typical tracking simulation. Some limitations such as inaccurate predictions and spatial complexity are also discussed. These methods can then be applied to strong-strong simulations in the future studies.

Speaker: William Fung (Facility for Rare Isotope Beams)

16:00 Demonstrating beam splitting through stable islands formed by the third-order resonance at the CERN Super Proton Synchrotron

In recent years, several new beam manipulation techniques have been proposed that exploit the crossing of nonlinear resonances and the use of stable islands of the transverse phase space. One such manipulation is a novel approach to slow extraction, which combines particle trapping in stable islands with the use of bent crystals to reduce losses on the extraction septum. As a first step towards testing this approach, measurements were performed at the CERN Super Proton Synchrotron (SPS) to demonstrate beam splitting using stable islands of the third-order resonance generated and controlled by sextupole and octupole magnets. The phase-space topology was reconstructed by displacing the beam and observing the turn-by-turn evolution of the signal of the beam position monitors. The beam splitting was achieved by varying both the machine tune and the radial steering of the beam. The measurement results were found to be in excellent agreement with the tracking simulations.

Speaker: Dora Veres (European Organization for Nuclear Research)

16:00 Design of beam phase space distribution to realize precise three-dimensional beam injection at J-PARC muon g-2/EDM experiment

In the J-PARC muon g-2/EDM experiment, a three-dimensional beam injection scheme will be adopted to inject a 300 MeV/c muon beam into a compact storage orbit. In this scheme, a low-emittance muon beam with X-Y coupling is injected from the edge of a solenoidal magnet and guided to a compact beam storage region where the magnetic field is precisely tunned for a muon g-2 measurement with a good systematic uncertainty.
The method to design the injected beam phase space distribution was previously unclear, as muons pass through an area with a largely position-dependent, non-linear, and time-dependent magnetic field created by the solenoidal fringe field and kicker field during the injection process.
This presentation introduces a new design method. By utilizing a linear approximation of beam transportation, an acceptance is defined for the injected beam distribution. This acceptance is represented as a three-dimensional hyperplane, allowing for a search of an optimal beam distribution by comparing it to beam phase space distribution candidates.
The presentation reports the procedure and results of this method, as well as its limitations due to the assumed linear approximation.

Speaker: Shinji Ogawa (High Energy Accelerator Research Organization)

16:00 Design progress of the booster synchrotron for Siam Photon Source II

The Siam Photon Source II (SPS-II) represents Thailand’s second synchrotron light source, designed to enhance the region’s scientific capabilities by providing high-energy, high-intensity synchrotron light for both academic and industrial research. The SPS-II will be situated in the Eastern Economic Corridor of Innovation (EECi) in Rayong Province. The SPS-II accelerator complex comprises three main parts: a linear accelerator (linac), a 3 GeV booster synchrotron, and a 3 GeV electron storage ring. The booster synchrotron is specifically designed to ramp beam energy to 3 GeV with a repetition rate of 2 Hz. This paper provides the latest update on the design of the booster synchrotron and related ramping studies. The study investigates the impact of magnetic field errors, multipole field imperfections, and alignment tolerances on beam parameters, with particular emphasis on the energy ramping process to ensure efficient and stable accelerator operation.

Speaker: Siriwan Jummunt (Synchrotron Light Research Institute)

16:00 Direct interpretation of coherent synchrotron radiation modeling from the Lienard-Wiechert equation with shielding

Coherent Synchrotron Radiation (CSR) plays a critical role in beam dynamics, significantly influencing beam shape and energy characteristics in particle accelerators. This study investigates the CSR effect through a comprehensive numerical approach, starting from the fundamental Lienard-Wiechert equation and utilizing an explicit, non-approximated methodology to explore beam energy dynamics. This paper focuses on simulating CSR effects in conjunction with the shielding effect from parallel plates, which are crucial in mitigating potential beam energy loss. By benchmarking results against Saldin's established work *, the study examines wakefield characteristics, particularly the high-peak behavior at small particle separations.

Speaker: Chia-Heng Huang (National Central Univeristy)

16:00 Dynamic aperture models for a time-varying high luminosity LHC lattice

The evaluation of dynamic aperture (DA) under time-dependent variations of lattice parameters is essential for understanding the long-term stability of particle motion in the Large Hadron Collider (LHC) and enhancing the future performance of the High-Luminosity LHC (HL-LHC). In this work, we develop DA models that address the complexities introduced by time-varying effects, with a focus on the operational challenges posed by luminosity levelling. Building on established DA scaling laws, we aim at capturing the impact of evolving machine conditions during levelling. An initial simulation study is presented that compares the effects on DA of different levelling schemes that are expected to be routinely used during the HL-LHC operation, providing key insight into extending current DA models to accommodate time-dependent perturbations.

Speaker: Carlo Emilio Montanari (University of Manchester)

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: Jianhao Xu (University of Science and Technology of China)

16:00 Effects of new SIRIUS IVUs on electron beam dynamics

Recently, two SIRIUS hard X-ray beamlines, EMA and PAINEIRA, were upgraded by replacing their previous insertion devices (IDs) with SIRIUS’s first in-vacuum undulators (IVUs). These new IDs have a period of 18.5 mm and can achieve a peak magnetic field of 1.24 T at a minimum gap of 4.3 mm. This paper reports on the effects of these new light sources on the electron beam, including static and dynamic orbit distortions, impacts on optics, injection efficiency, and changes in the storage ring’s equilibrium parameters.

Speaker: Gabriel Ascenção (Brazilian Synchrotron Light Laboratory)

16:00 Effects of tracking errors on the SOLEIL II booster

For the upgrade of SOLEIL II a new booster with reduced transverse and longitudinal beam sizes is required. The new booster follows a 16 BA Higher-Order Achromat lattice with a reduced emittance to about 5 nm rad at 2.75 GeV. At the end of the ramp an emittance exchange is foreseen to allow for more flexibility in the injection parameters into the storage ring. In order for a good efficiency of the emittance exchange, the coupling of the lattice has to be well controlled. This is achieved with a LOCO routine for coupling using 10 skew quadrupoles, but the so-called random tracking errors from the ramping magnet power supplies introduce noise in the response matrix measurement.Furthermore, an online measurement setup for the beam sizes using visible light and a slit mirror needs a careful beam position evaluation, which may be affected by tracking errors. For both these items, this contribution outlines the efforts and results achieved.

Speaker: Patrick Schreiber (Synchrotron soleil)

16:00 Electromagnetic modeling of cryogenic vacuum chambers using a hybrid neural network-boundary integral equation approach

Recently, artificial intelligence and machine learning are actively discussed in the particle accelerator community. The physics-informed neural network (PINN) method, which is a powerful approach for solving differential equations with deep neural networks (DNN), has been successfully applied to the calculation of electromagnetic fields and beam coupling impedances in particle accelerators. In this work, a hybrid PINN method combined with the boundary integral equation (BIE) method is developed to calculate the fields and impedances in accelerator vacuum chambers at cryogenic temperature. The surface impedance boundary condition for the anomalous skin effect is included to model the electromagnetic characteristics of chamber wall surfaces. Transfer learning can accelerate training processes for DNN parameters in a wide frequency band. The hybrid PINN-BIE approach is verified through applications to various chamber cross sections.

Speaker: Kazuhiro Fujita (Saitama Institute of Technology)

16:00 Energy ramping simulation for TPS booster ring

The Taiwan Photon Source (TPS) booster ring accelerates electron beams from the linear accelerator (lin-ac) output energy of 150 MeV to 3 GeV for storage ring injection. In the event of partial RF station failure in the linac, the available beam energy may be reduced to 100 MeV. Preliminary machine tests have demonstrated multi-turn beam circulation in DC mode and successful acceleration from 127.5 MeV to 3GeV. Beam dynamics simulations using elegant evaluate the effects of dipole field errors, magnet multipole and alignment errors, chamber aperture constraints. Additionally, space charge effects at 100 MeV, due to the low relativistic factor, could lead to incoherent tune shifts, and potential beam loss. This study investigates the feasibility of operating the TPS booster at 100 MeV injection and ramping to 3 GeV with a focus on beam dynamics considerations

Speaker: Mr Mau-Sen Chiu (National Synchrotron Radiation Research Center)

16:00 Estimation of the microwave instability at ALBA

In a collaborative work between ALBA and KEK the computation of the microwave instability threshold of the current ALBA ring was initiated. This analysis involves solving the dispersion relation equation and conducting simulations using a Vlasov-Fokker-Planck (VFP) solver. The longitudinal wake fields of geometric origin of all vacuum elements were computed with GdfidL using a bunch whose length is at least 5x smaller than the bunch length given by usual 3MV RF-voltage applied at ALBA. The resistive wall contribution was computed at first as longitudinal impedance by IW2D** to be converted in a second step into wake fields via Fourier transform. The CSR contribution will also be considered. The impact of the 3 types of wakes on the microwave instability will be studied. The microwave instability single bunch threshold will be computed combining the 3 contributions. This work also serves as a preparation of the future evaluation of the microwave instability of the ALBA upgrade, which is expected for 2030.

Speaker: Thomas Günzel (ALBA Synchrotron (Spain))

16:00 Evaluation and validation of PyOrbit cavity models for online simulations at ESS

In a linear accelerator (linac), having a reliable model of the accelerating cavity is critical, as it is the primary element influencing particle dynamics. At the European Spallation Source (ESS), the TraceWin software is used for linac design, implementing thin-gap and multi-cell models, with both linearized matrix-based and field-map solvers. However, these models cannot be used online, as TraceWin is not integrated with the ESS control system, EPICS. To enable online simulations, PyOrbit—a code developed in collaboration with the Spallation Neutron Source (SNS)—is being considered. This paper evaluates and compares the six cavity models available in PyOrbit—Simplified Matrix Model, Base RF Gap Model, Transit Time Factors RF Gap Model, Three Point TTF Model, Direct Tracking through 3D RF Gap Field Model, and OpenXAL RF Gap Model—against the TraceWin cavity models to validate their suitability for ESS requirements.

Speaker: Emanuele Laface (European Spallation Source)

16:00 Experimental validation of parallel quadrupole beam-based alignment at KARA

The Karlsruhe Research Accelerator (KARA), a synchrotron light source and test facility, at the Karlsruhe Institute of Technology (KIT), offers excellent conditions for testing different Beam-Based Alignment (BBA) approaches. Classical BBA approaches estimate the offset between the magnet and the closest BPM for one magnet at a time, and the required time for the BBA scales linearly with the number of magnets. Therefore, this approach is unsuitable for large storage rings like the Future electron-positron Circular Collider (FCC-ee). The time required is reduced using parallel BBA, where the magnet offset for several magnets is determined simultaneously. In this contribution, we compare new methods of parallel and individual BBA for quadrupoles at KARA. The measurement results are complemented with simulations using Xsuite and optics measurements.

Speaker: Patrick Schreiber (Karlsruhe Institute of Technology)

16:00 Exploring the nonlinear dynamics performance for Hefei Advanced Light Facility from the linear optics

Hefei Advanced Light Facility (HALF) is a 2.2 GeV diffraction-limited storage ring designed with a modified hybrid six-bend achromat (H6BA) lattice. The present baseline lattice has a relatively large dynamic aperture and a reasonable Touschek lifetime. But it is better to further improve the nonlinear dynamics performance when considering the effect from errors and insertion devices. For a HMBA lattice, there are generally very few optimization knobs when linear optics fixed. So, in this paper, the optimization potential of nonlinear dynamics will be explored for HALF in the linear optics optimization. And several lattice solutions with larger dynamic apertures or momentum apertures will be obtained.

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

16:00 Formulas of coherent synchrotron radiation induced microbunching instability in an arbitrary dogleg lattice

The microbunching instability (MBI) has long been a persistent issue in high-brightness electron beam transport. The dogleg structure, a dispersive configuration composed of two quadrupole magnets and dipole magnets, has drawn attention in recent studies. It has been pointed out that the Landau damping effect can be enhanced to effectively suppress the microbunching instability by adjusting the strength of two quadrupole magnets preceding the dogleg structure. In this work, we derive an analytical formula for the CSR-induced microbunching gain in a dogleg lattice based on the iterative approach. The formulas have been benchmarked against semi-analytical Vlasov calculations. The analytical formulas obtained in this paper can be used to explore the influence of the strength of the quadrupole magnets in front of the dogleg lattice on the final microbunching instability, and also to verify the effectiveness of suppressing MBI in the dispersive region where the dogleg is located.

Speaker: Bingxi Liu (Huazhong University of Science and Technology)

16:00 Hamiltonian preserving nonlinear optics

We present a method of constructing a nonlinear accelerator lattice that has at least one approximate integral of motion that is given upfront. The integral under consideration is a Hamiltonian in normalized (canonical) coordinates that is preserved by a lattice with a given accuracy. A connection between the integrator of a Hamiltonian in normalized coordinates and a real lens arrangement is established through the well know symplectic integration schemes. Based on the introduced concept when accelerator is considered as an analog computer, we to produce several nonlinear lattices and illustrate the method via the simulations. We demonstrate that the method is robust and can tolerate considerable deviations from the ideal configuration.

Speaker: Stanislav Baturin (ITMO University)

16:00 High Luminosity LHC optics: Machine development results

As the High Luminosity LHC (HL-LHC) era approaches, precise control of the accelerator becomes increasingly critical. Machine studies are essential to address the forthcoming challenges and develop correction strategies based on experimental measurements. Although the upgraded inner triplets are not yet available, key features of the HL-LHC optics can still be investigated. This includes exploring the high Achromatic Telescopic Squeeze (ATS) factors in the neighboring arcs of the high-luminosity interaction regions, particularly under flat optics configurations. A beta blow-up is also implemented in the long straight section containing most of the beam instrumentation to improve their sensitivity at top energy. This paper presents experimental measurements, evaluates arc phase errors, and discusses the implementation of local corrections. Sextupole bumps in the arcs were employed to mitigate these errors, demonstrating their effectiveness in optimizing machine performance.

Speaker: Yannis Angelis (Aristotle University of Thessaloniki)

16:00 Impact of linear imperfections in the high luminosity LHC separation dipole magnets

Magnetic field measurements have been performed after fabrication of new separation dipoles for the low beta-star insertion regions of the High Luminosity LHC project*. In this paper, the effect of the linear imperfections of these magnets on coupling, beam size and beta-beating are evaluated using MAD-X simulations. The results indicate that the impact of normal-oriented quadrupole errors are small and easily correctable, while for skew-oriented quadrupole imperfections corrections require a significant fraction of the arc skew quadrupoles strength. Subsequent simulation studies were therefore performed to devise potential mitigation strategies, the results of which are also reported here.

Speaker: Joschua Dilly (European Organization for Nuclear Research)

16:00 Impact of non-linearities on collimation losses at the CERN Large Hadron Collider

Since the start of the third operational run of the CERN Large Hadron Collider (LHC) in 2022, multiple observations have highlighted the significant influence of non-linearities within the accelerator on the collimation loss patterns of circulating beams. Understanding this phenomenon is particularly relevant for qualifying and validating collimation performance for machine operation at high intensity. In this study, we explore the capability of advanced numerical simulations to reproduce the observed loss patterns, incorporating a detailed representation of various nonlinearities. These include strong octupole fields and high chromaticity. An in-depth analysis comparing the simulation results to experimental measurements was conducted. These findings provide valuable insights into the interplay between machine non-linearities and beam losses.

Speaker: Frederik Van der Veken (European Organization for Nuclear Research)

16:00 Impact of the cSTART impedance on beam dynamics

The combination of a compact storage ring and a laser-plasma accelerator (LPA) can serve as the basis for future compact light sources. One challenge is the large momentum spread (about 2%) of the electron beams delivered by the LPA. To overcome this challenge, a very large acceptance compact storage ring (VLA-cSR) was designed as part of the compact STorage ring for Accelerator Research and Technology (cSTART) project, which will be realized at the Karlsruhe Institute of Technology (KIT, Germany). Initially, the Ferninfrarot Linac- Und Test-Experiment (FLUTE), a versatile source of ultra-short bunches, will serve as an injector for the VLA-cSR to benchmark and emulate LPA-like beams. In a second stage, a laser-plasma accelerator will be used as an injector. The large-momentum spread bunches in non-equilibrium and with charges from 1 pC to 1 nC and lengths from few fs to few ps pose challenges for the beam dynamics simulations. An understanding of the ultra-short bunch dynamics also requires an impedance model up to high frequencies. Here, we present first results on the impact of the machine impedance to the beam dynamics.

Speaker: Dr Markus Schwarz (Karlsruhe Institute of Technology)

16:00 Impact of the geometric impedance of collimators on beam stability in FCC-ee

Beam stability in the FCC-ee collider is strongly influenced by transverse and longitudinal beam coupling impedance. Developing a flexible and comprehensive impedance model is crucial for accurately evaluating and mitigating instabilities as machine parameters evolve. This study investigates the effect of the FCC-ee collimation system, identifying it as a dominant source of total machine impedance. Both resistive and geometric contributions are analyzed, with geometric effects found to play a critical role in shaping the overall impedance landscape. Accurately modeling collimators’ geometric impedance is essential for beam stability assessment. Such modeling enables global impedance considerations, accounting for the interplay between different accelerator elements and guiding the definition of critical design parameters.

Speaker: Dora Gibellieri (European Organization for Nuclear Research)

16:00 Impact of the inner triplet polarity on the optics commissioning of the LHC in 2024 and 2025

To mitigate the risk of radiation damage induced failure while operating the LHC beyond its initial integrated luminosity target, changes to the triplet polarity and crossing angles have been applied in the two main experimental interaction regions of the LHC. This allows for a more distributed radiation deposition in the insertion region magnets, which should allow their survival until they are replaced as part of the High Luminosity LHC upgrade from 2026-2030. These changes in the optics during 2024 and 2025 came with important challenges regarding machine commissioning and optics correction. In this paper, we discuss our experience of linear optics correction for the various triplet polarity configurations and review the implications for nonlinear optics corrections.

Speaker: Joschua Dilly (European Organization for Nuclear Research)

16:00 Impedance benchmarking of resistive wall and tapered transitions for the PF-HLS

The PF Hybrid Light Source (PF-HLS) has been proposed in the High Energy Accelerator Research Organization (KEK), capable of utilizing both high-quality beams from a superconducting linac and beams from a low-emittance storage ring. The coupling impedance will cause beam instability, which must be carefully handled. It is essential to benchmark impedance models using analytical methods and different simulation codes. This paper focuses on the impedance benchmarking of resistive wall and tapered transitions in PF-HLS. The regular round chamber (radius of 12 mm), insertion device (ID) chamber (half-height of 4 mm), and the corresponding tapered transitions are studied. Simulation codes, including ImpedanceWake2D (IW2D), CST, and Azimuthal Beam Cavity Interaction (ABCI), are used. For resistive wall calculations, some analytical formulae describing the round chamber impedance and the Yokoya form factors of the ID chamber are applied. For tapered transitions, some formulae calculating the impedance at low-frequency regions (inductive regime) are chosen to compare with results from CST. In high-frequency regions, the impedance result comparison between CST and ABCI is carried out.

Speaker: Dr Baoyuan Bian (High Energy Accelerator Research Organization)

16:00 Impedance optimization for the HALF storage ring

Over the past year, we have conducted comprehensive impedance optimization calculations for the vacuum components designed for the Hefei Advanced Light Facility (HALF) storage ring. Our calculations indicate that specific components, which have a cavity-like or tapered structure, possibly exhibit a relatively strong trapped-mode impedance in the longitudinal or transverse directions. In order to suppress these trapped modes, we have proposed structural optimization recommendations, which were ultimately adopted for HALF. In this paper, we will present a detailed account of these suggestions and the impedance outcomes before and after the optimization.

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

16:00 Improving the beam extraction efficiency from SPS to the North Area at CERN using octupole phase space folding technique

The High Intensity ECN3 (HI-ECN3) project aims to increase the number of protons per pulse delivered to a new experimental facility in CERN’s North Area up to $\sim 4 \cdot 10^{19}$ per year. Such an upgrade requires the reduction of the beam loss at SPS electrostatic septum (ZS) by at least a factor of four, since the activation of this device is the main factor constraining transition to the higher beam intensity. In this work we demonstrate one of the possible solutions to this problem that relies on octupole assisted folding of the beam in phase space. Implementation of this technique allowed to significantly reduce the losses at the ZS whilst transferring the beam through the LSS2 line, which connects the SPS and the transfer lines in the North Area, without deteriorating the transmission.

Speaker: Pablo Andreas Arrutia Sota (European Organization for Nuclear Research)

16:00 Introducing an open-source 3D time-domain electromagnetic wakefield solver for beam-coupling impedance simulations

The determination of electromagnetic wakefields and their impact on accelerator performance is a longstanding challenge in accelerator physics. These wakefields, induced by the interaction between a charged particle beam and the surrounding vacuum chamber structures, significantly affect beam stability and power dissipation. Accurate characterization of these effects via beam-coupling impedance is crucial for predicting and mitigating performance limitations. While analytical methods are sufficient for simple geometries, realistic accelerator components require full-wave, three-dimensional numerical solutions of Maxwell's equations. In alignment with CERN's Open Science initiative, this contribution introduces an open-source 3D electromagnetic time-domain solver specifically designed for computing wake potentials and impedances in arbitrary geometries. The solver’s numerical implementation, optimized for CUDA-enabled GPUs, is presented and validated through benchmarks against established commercial codes. By fostering a collaborative framework, this solver aspires to address emerging challenges in accelerator design.

Speaker: Elena de la Fuente (European Organization for Nuclear Research)

16:00 Investigating ion beam loss mechanisms at the SPS flat bottom

The long injection segment (flat bottom) of the cycle in the Super Proton Synchrotron (SPS) used for filling the Large Hadron Collider (LHC) with Pb ion beams, exhibits strong beam losses and transverse emittance growth. During the 2024 run, large improvements of the beam transmission could be made such that record intensities could be delivered to the LHC. In particular, these improvements were enabled by operational measures such as working point optimization and a numerical compensation scheme for the 50 Hz ripple from the main quadrupole power converters. This paper provides a summary of these improvements, and presents recent advancements in particle tracking simulations of the SPS flat bottom, including effects such as intra-beam scattering and space charge in the presence of tune modulation induced by power converter noise. These simulations are compared with transverse and longitudinal beam measurements. The relative importance of each effect and their estimated impact on the future ion programmes at CERN are discussed.

Speaker: Felix Soubelet (European Organization for Nuclear Research)

16:00 Investigation of the microwave instability at MAX IV laboratory in combination with intra-beam scattering

With the increasingly challenging parameters in 4th generation synchrotron light sources, collective effects causing instabilities are putting even stronger limitations on the area of stable operation. The microwave instability (MWI) is a longitudinal single-bunch instability driven by the geometric and the resistive-wall impedances. While the instability typically does not result in a beam loss, the resulting turbulent dynamics are accompanied by an increased energy spread and therefore deteriorate the light source performance. The threshold current depends on different beam parameters and can, without mitigation, for recently upgraded or currently under design light sources, be as low as or lower than the intended design current per bunch. At the same time, the instability threshold is also influenced by other collective effects such as the intra-beam scattering (IBS). The influence of the IBS on the microwave instability has been studied for the 3 GeV storage ring at the MAX IV laboratory. The presented experimental results show the expected influence on the MWI threshold by the coupling strength due to the resulting changes in the IBS.

Speaker: Miriam Brosi (MAX IV Laboratory)

16:00 Layout optimization and comparison of a Carbon-ion gantry based on different mechanical structures

Carbon ion therapy is one of the most effective radiotherapy methods for cancer treatment, offering superior dose conformality compared to conventional radiation therapies. The combination of carbon ion treatment with a gantry further enhances treatment effectiveness and safety. When designing a gantry, the magnet aperture must consider both the beam envelope and the beam position errors all along the gantry beamline. These errors may arise from magnetic field errors, imperfect magnet alignment, construction inaccuracies and mechanical design choices. A well-matched optics guarantees a low beam envelope; however, this does not always correspond to an optimization of the space occupied by the beam after introducing error sources and related corrections. Thus, a novel methodology that integrates optics and mechanical studies has been developed. By combining mechanical deformation analyses and optics correction optimization algorithms, this study provides a comprehensive solution for the HITRIplus carbon ion gantry design. A detailed analysis of the impact of two different design options for the supporting system of the SC magnets is provided.

Speaker: Simone Savazzi (National Center for Oncological Hadrontherapy)

16:00 LHC beam-beam wire compensator impedance contribution

The mitigation of long-range beam-beam interactions remains a critical challenge for maximizing the luminosity performance of the Large Hadron Collider (LHC). Previous experimental studies have demonstrated that long-range beam-beam wire compensation can effectively counteract long range beam-beam interactions, leading to enhanced beam lifetime and increased integrated luminosity. A direct-current (DC) wire compensator has been successfully prototyped and thermo-mechanically validated at reduced scale. This investigation provides a characterization of the beam-coupling impedance contributions of the proposed compensator device, quantifying both beam-induced heating and implications for beam stability. Critical aspects of the design have been identified and impedance reduction strategies have been applied, taking into consideration constraints due to compatibility requirements with existing LHC systems during the High-Luminosity LHC (HL-LHC) phase. The study shows that, while further optimizations may be pursued, no fundamental impedance-related showstoppers have been identified for the implementation of wire compensation.

Speaker: Leonardo Sito (University of Naples Federico II)

16:00 Luminosity modeling of the LHC operation and performance projections for HL-LHC

The LHC luminosity model is a powerful tool for studying the evolution of beam and machine parameters during the LHC operation. The model includes important effects that are present in LHC operation such as Intra-Beam Scattering, synchrotron radiation and burn-off. By comparing model predictions with experimental data, the presence of additional emittance blow-up and intensity loss mechanisms can be identified and then further studied. Using this model for comparing different configurations such as optics, filling schemes and beam types, allows identifying the best strategy to be adopted in operation to maximize integrated luminosity. In this contribution, we show the benchmarking of this model with data from the presently ongoing LHC Run 3, and its application to predicting the integrated luminosity for its future High-Luminosity LHC upgrade.

Speaker: Sofia Kostoglou (European Organization for Nuclear Research)

16:00 Metamaterial absorbers for beam-coupling impedance mitigation

Charged particle bunches traversing cavity-like discontinuities in the beam pipe at relativistic velocities excite electromagnetic resonant modes that can detrimentally affect the dynamics of trailing bunches. This beam-cavity interaction, characterized in the frequency domain through the concept of beam-coupling impedance, poses significant challenges for beam stability and performance in high-energy particle accelerators. While conventional mitigation strategies encompass higher-order mode (HOM) couplers and lossy ferrite insertions, novel approaches leveraging metamaterial properties offer promising alternatives for selective mode damping. This investigation explores advanced metamaterial-based structures designed to specifically target and attenuate higher-order modes, thereby selectively reducing the beam-coupling impedance resonances.

Speaker: Leonardo Sito (University of Naples Federico II)

16:00 New results of nonlinear quasi-integrable lattice studies

Nonlinear integrable optics is a promising design approach for suppressing fast collective instabilities. To study it experimentally, a new storage ring, the Integrable Optics Test Accelerator (IOTA), was built at Fermilab. IOTA has recently completed its fourth electron run, achieving the design 150 MeV energy and optimal beam parameters. This report presents the results for the quasi-integrable Henon-Heiles octupole system. We obtained tune spread and dynamic aperture in agreement with tracking simulations and robust to other nonlinear perturbations. Extensive analysis is given of recovered single-particle phase space dynamics, showing improved invariant jitter consistent with intended effective Hamiltonian. We conclude by outlining plans towards proton studies and a direct demonstration of reduced beam losses in the intense space charge regime.

Speaker: Nikita Kuklev (Argonne National Laboratory)

16:00 Nonstationary dynamics of vortex electron beam in magnetic lens

The Landau states of electrons with orbital angular momentum in magnetic fields are important in the quantum theories of synchrotron radiation at storage rings and in many other areas. In realistic scenarios, electrons are often born inside the field or injected from a field-free region, requiring nonstationary quantum states to account for boundary or initial conditions. This study presents nonstationary Laguerre–Gaussian (NSLG) states in a longitudinal magnetic field, characterizing vortex electrons after their transfer from vacuum to the field. Comparisons with Landau states show that the r.m.s. radius of the electron packet in the NSLG state oscillates in time around a significantly larger value than that of the Landau state. This quantum effect of oscillations is due to boundary conditions and can potentially be observed in various problems, particularly when using magnetic lenses of linear accelerators and electron microscopes. Analogies are drawn between a quantum wave packet and a classical beam of many particles in phase space, including the calculation of mean emittance of the NSLG state as a measure of its quantum nature.

Speaker: Ilia Pavlov (ITMO University)

16:00 Numerical modeling of the CERN PS booster cavity feedback loops

The Radio-Frequency (RF) system of the CERN Proton Synchrotron Booster (PSB) features Finemet-loaded cavities that cover a wide range of frequencies. This system generates a significant broad-band longitudinal impedance, which must be mitigated to maintain beam stability, particularly at higher beam intensities. To counteract the induced voltage, a direct RF feedback is employed over the entire operational frequency range. It is complemented by a multi-harmonic feedback that applies narrow-band signal processing to reduce the cavity impedance at integer multiples of the revolution frequency. Recent measurements have revealed that these long-delay cavity loops implemented in the Low-Level RF (LLRF) system have a substantial effect on beam dynamics. To validate the impedance model in the closed-loop regime, a detailed model of their behaviour is necessary. This contribution outlines the development process of the numerical model for the PSB cavity feedback loops for particle tracking simulations, which is based on dedicated measurements used to characterise the feedback performance. Comparisons between simulations and measurements are carried-out to assess the validity of the modeling.

Speaker: Mariangela Marchi (Sapienza University of Rome)

16:00 Observation of transverse resonance island buckets at the ESRF EBS

The presence of third order horizontal resonance island buckets at the ESRF EBS has been observed in simulations and in the machine. The islands appear at a few mm distance from the core with a specific horizontal tune and octupole setting. When the electrons are kicked with an injection kicker, a fraction of the beam can be captured in the island. The procedures to send the beam into the island and to measure the capture rate and the lifetime of the beam in the island are described. The dependency of the presence of stable islands with different horizontal and vertical tunes and different octupole settings are shown.

Speaker: Nicola Carmignani (European Synchrotron Radiation Facility)

16:00 On the optimization of the non-linear lattice of BESSY III

Helmholtz-Zentrum Berlin plans to construct a fourth-
generation greenfield synchrotron light source in the early
2030s to replace BESSY II, a 1.7 GeV machine that has been
running since 1998. The optimization of the linear lattice
already considers non-linear aspects, such as minimizing
the necessary sextupole strength and, for the minimal case
of two families of sextupoles, phase cancellation to reduce the resonant driving terms. In preparation for the final optimization of 8 sextupole families and the single octupole, different approaches are compared: multi-objective genetic optimization, for a lattice with given error sets and orbit
correction on the one hand, and the minimization of the
resonant driving terms and the detuning terms on the other
hand. Here, analytic formulas are used, so after a single
evaluation of the Twiss parameters, the driving terms can
be determined for different combinations of sextupole and
octupole values. The results will determine the strategy for
optimizing the lattice’s non-linear behavior, i.e., dynamic
aperture and momentum acceptance, taking the efficiency
of the optimization into account.

Speaker: Bettina Kuske (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 Online optimization of beam lifetime by Bayesian Optimization in TPS

The beam lifetime in synchrotron light sources is critically influenced by nonlinear beam dynamics, particularly in low-emittance storage rings where the Touschek effect dominates. At the Taiwan Photon Source (TPS), a third-generation 3 GeV storage ring, optimization of harmonic sextupole magnet strengths has been conducted using Bayesian Optimization (BO) techniques to minimize beam loss monitor (BLM) readings and thereby enhance beam lifetime. This study demonstrates an integrated approach to nonlinear optics tuning using machine learning, with constraints on chromaticity correction. The experimental implementation involves tuning harmonic sextupole families. Results indicate significant improvements in lifetime while maintaining machine stability, demonstrating the potential of data-driven control in modern accelerator operations, establishing this technique as a powerful tool for synchrotron light source operation. This paper details the implementation, experimental validation, and performance analysis of BO in optimizing beam lifetime at TPS.

Speaker: Mr Mau-Sen Chiu (National Synchrotron Radiation Research Center)

16:00 Optics function determination using luminosity data

Determining the betatronic waist shift and the $\beta^*$ at the interaction points through K-modulation in the Large Hadron Collider presents considerable challenges. This paper introduces a novel method for the measurement of these quantities, based on luminosity measurements and the van der Meer technique for reconstructing transverse bunch profiles.
The strategy involves colliding multiple bunches with distinct emittances, performing emittance scans, and subsequently shifting the collision point along the longitudinal plane via RF cogging. This shows promising potential to reduce uncertainties in the optics parameters at the interaction point and to obtain measurements of the absolute beam emittance. The first measurement using this technique was carried out at the Large Hadron Collider, with the analysis and findings discussed in detail.

Speaker: Joanna Wanczyk (European Organization for Nuclear Research)

16:00 Optics optimization and commissioning simulations for Elettra 2.0

Optimization of dynamic aperture is a challenging aspect of low emittance storage ring lattice design. A large dynamic aperture is favourable for efficient injection and long beam lifetime. Several methods like simple scanning of sextupoles and octupoles strength and genetic optimization with different configurations have been successfully combined to enlarge the dynamic aperture of Elettra 2.0 and ensure high efficiency injection. Using the optimized machine we then study its commissioning via simulations including and discussing the various stages from injection to the first turn, to accumulation.

Speaker: Stefano Krecic (Elettra-Sincrotrone Trieste S.C.p.A.)

16:00 Optimising multi-turn extraction at CERN using transverse feedback

Initial experimental investigations of transverse beam splitting, carried out at the CERN Proton Synchrotron, have demonstrated that transverse feedback is highly effective in controlling the characteristics of the transversally split beam. The feedback notably improves the intensity distribution among the beamlets and the emittance of the core, which is the portion of the beam remaining near its centre after the resonance-crossing process. The transverse feedback is set in resonance with the horizontal betatron tune while the tune crosses the fourth-order resonance, creating a double-resonance condition. A simple Hamiltonian model has been employed to explore the underlying double-resonance mechanism. This paper thoroughly examines detailed numerical simulations based on a realistic lattice model alongside beam measurements, to identify optimisation strategies for the use of transverse feedback in controlling the properties of split beams.

Speaker: Oleksandr Naumenko (European Organization for Nuclear Research)

16:00 Optimization of SHINE for attosecond pulse generation

High-power attosecond X-ray pulses play a critical role in many areas of research like ultrafast nonlinear spectroscopy, structural and electronic damage-free X-ray measurements. For free-electron laser facilities, the self-chirping operation mode has been demonstrated as an effective method for generating terawatt-level X-ray attosecond pulses. To compress the bunches under this mode, the transport line should provide a positive R56. We report on the optimization of the LTU1 beamline in the switchyard section of SHINE, which achieves independent variable of both R56 and dispersion. This development provides crucial support for future attosecond pulse operation at SHINE.

Speaker: Bingyang Yan (Shanghai Institute of Applied Physics)

16:00 Optimizing beam-beam beta-beating for luminosity enhancement at the LHC

The optimization of LHC operation is focused on achieving the highest possible integrated luminosity to maximize experimental data collection. Given the limitations of current detector systems, maintaining a constant level of integrated luminosity has become more critical than achieving a high peak luminosity. Techniques such as beta-leveling and separation levelling have already been implemented to adjust luminosity and enhance operational efficiency. This study describes how the beam-beam beta-beating effects propagating between the multiple experimental interaction points can serve as an additional mechanism to further increase the total integrated luminosity. The operational solutions and impact on performance will be shown for both the current LHC and its future High Luminosity upgrade.

Speaker: Joanna Wanczyk (European Organization for Nuclear Research)

16:00 Orbit error correction schemes for the Helium Light Ion Compact Synchrotron HeLICS

The Helium Light Ion Compact Synchrotron (HeLICS) is an innovative synchrotron design for cancer treatment currently under development in the context of the Next Ion Medical Machine Study (NIMMS) at CERN. As part of the lattice design, the beam size around the HeLICS circumference is evaluated and the optics functions optimized in order to meet the aperture requirements imposed by the magnet design. Furthermore, the impact of orbit errors arising from magnet misalignments is addressed, taking into account the required margins and tolerances. Correction strategies are proposed to compensate these alignment errors and provide sufficient orbit correction.

Speaker: Vincenzo Sansipersico (European Organization for Nuclear Research, Riga Technical University)

16:00 Parametric optics for FUDU lattices with strongly focusing undulators

In low-energy FEL beamlines, like SXFEL-SBP at the Shanghai Synchrotron Radiation Facility and FLASH1 and FLASH2 at DESY, SASE undulators with perfectly reasonable strength may dynamically affect the optics of the Focusing-Undulator-Defocusing-Undulator (FUDU) cells, pre-matched for a given fixed set of undulator parameters, so violently that a dynamical re-adjustment of the FUDU quadrupoles becomes mandatory.
Here we refine and generalize a result reported at the FEL conference 2024. Our almost-analytical result allows implementation in the control system, and is valid for fairly general symplectic coupling-free perturbing matrices. In an approximative sense it includes undulators changing along the beamline and even missing undulators in given cells.

Speaker: Mathias Vogt (Deutsches Elektronen-Synchrotron DESY)

16:00 Photon masks designed for the HALF storage ring

The Hefei Advanced Light Facility (HALF) storage ring employs more than 200 photon masks to shield thermally sensitive vacuum components from synchrotron radiation. The impedance introduced by these masks is highly dependent on their intrusion depth. This paper presents a straightforward method for assessing the requisite intrusion depth and the shielded photon power for individual masks. Furthermore, we demonstrate the mask design and impedance results for the HALF storage ring.

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

16:00 Preliminary electromagnetic design of a high-temperature superconducting superbend for the Hefei Advanced Light Facility

The National Synchrotron Radiation Laboratory is constructing a 2.2 GeV diffraction-limited storage ring, the Hefei Advanced Light Facility (HALF), using the modified hybrid 6BA lattice, which consists of a total of 20 cells. The synchrotron radiation primarily covers the vacuum ultraviolet (VUV) to soft X-ray bands. To extend the photon energy into the hard X-ray range, two 0.9 T normal-conducting bending magnets are to be replaced with 6 T superconducting magnets. This upgrade demands a magnet that achieves high magnetic field strength while seamlessly integrating with the storage ring's compact geometry and operational constraints. The C-shaped yoke design allows the magnet to be easily inserted and removed from its position in the storage ring vacuum chamber. The coil is planned to be wound with ReBCO tape due to its higher current-carrying capacity and critical temperature. This paper discusses the design requirements of the superbend and presents two electromagnetic design schemes.

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

16:00 Preliminary study on the collective effect in a high-current and low-energy storage ring

High-current and low-energy storage ring is an essential part of accelerator for industrial application. However, high intensity poses great challenge to beam stability through collective effects, which can be exacerbated at low energy. In this paper, we present a preliminary study on various collective effects in an application-oriented storage ring. The classical theory is reviewed, and numerical analysis is performed on Touschek scattering, intra-beam scattering, resistive-wall, beam-ion and so on. In addition, Particle tracking is carried out using elegant, mbrack2, etc. Lastly, techniques to improve the current threshold are also discussed.

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

16:00 Progress on the 5BA lattice studies for ALBA-II

ALBA-II is progressing in the definition of an upgrade lattice that meets the requirements of the beamlines and perform well in terms of dynamics aperture and lifetime. The last changes were focused on further decreasing both the emittance (200 pm*rad) and the beta functions at the straight sections (around 2 m) for the improvement of the beamlines performances. The efforts to guarantee a good performance of such a lattice have been focused on the improvement of a horizontal dynamic aperture larger than 6 mm (needed for off-axis injection) and of a lifetime around 10 hours. Octupole magnets next to each sextupole have been introduced to correct the large tune shift with amplitude that is limiting the dynamic aperture. Simulations of the lattice commissioning and robustness with magnet, alignment and instrumentation errors are being carried out. The efficiency of the off-axis injection process including both lattice and pulsed elements errors is also under evaluation.

Speaker: Francis Perez (ALBA Synchrotron (Spain))

16:00 Resistive wall impedance calculations and effects of NEG coated insertion device vacuum pipes for the PF-HLS ring

I show analytical expressions of the longitudinal and transverse impedances of a two-layered circular pipe and their practical expressions at high frequencies derived by using asymptotic expansions of the Bessel functions. These expressions are applied to resistive-wall impedance calculations of NEG-coated insertion-device(ID) pipes for the PF-HLS ring*, which is proposed as a 2.5/5.0 GeV energy switchable ring and can simultaneously provide synchrotron light pulses emitted by electron bunches stored in the ring and by extremely short electron bunches (50 fs in length) injected from the superconducting linac. Both real and imaginary parts of the impedances rise up in high frequency regions depending on the NEG coating thickness. The heating powers of the ID pipes are calculated from the real parts of the longitudinal impedances for the stored electron beam and for the short electron bunches injected from the superconducting linac. The kick factors and the coherent betatron tune shifts due to the ID pipes are calculated from the imaginary parts of the transverse impedances for the stored electron beam. These dependences on the NEG-coating thickness are shown in this presentation.

Speaker: Norio Nakamura (High Energy Accelerator Research Organization)

16:00 Resonance Driving Terms characterization at VEPP-2000 collider

The VEPP-2000 collider is a compact machine, which uses the round-beam concept to achieve high luminosity. Its compact size (24 m in circumference) limits the free space between the magnetic elements. Only 4 BPMs are installed in the ring with large phase advance between them (~2 pi). The key to improve its luminosity is to reduce the power of resonances. The implementing of the RDT measurement technique with our limitations is discussed. The presented experimental data gives basic information on the location of the considered magnetic perturbation causing the RDT.

Speaker: Danil Chistiakov (Russian Academy of Sciences)

16:00 Review of linear and nonlinear optics measurements in the CERN LHC

The LHC is approaching the end of its third operational run, with machine protection and performance having demanded an excellent control of the single-particle dynamics. Additionally, the requirement to rapidly commission multiple diverse sets of optics configurations within each year and from year-to-year, placed clear demands on the measurement and correction methods employed. Tight tolerances on the linear optics have been consistently achieved, with the drive to ever-more pushed optics for the High Luminosity LHC era continuing to introduce new challenges. Routine control of linear coupling has been an operational necessity, while significant progress has also been made extending the understanding and control of the optics into the nonlinear regime. This paper presents the key methods used, the results obtained, and discusses the challenges to control of the beam-optics in the LHC.

Speaker: Ewen Maclean (European Organization for Nuclear Research)

16:00 Simulation-based optimization of the injection of ultrashort non-Gaussian electron beams into a storage ring

The compact STorage ring for Accelerator Research and Technology (cSTART) project at the Karlsruhe Institute of Technology (KIT, Germany) aims to explore non-equilibrium electron beam dynamics and injection of laser-plasma accelerator (LPA) bunches. The Very Large Acceptance compact Storage Ring (VLA-cSR) is also filled by a second injector that delivers ultra-short bunches from the Ferninfrarot Linac- Und Test-Experiment (FLUTE). Injection from FLUTE into the VLA-cSR is achieved via a complex 3D injection line featuring tilted deflections, negative dispersion, and extreme compression to femtosecond bunch lengths.
From this transport, the bunch develops pronounced non-Gaussian tails; nevertheless, near the injection point, it is crucial to ensure matching to both the dynamic aperture and the periodic solutions of the storage ring dynamics. The 25 quadrupole magnets of the injection line make conventional optimization methods impractical. This contribution discusses the development of the magnet optics to meet these extreme requirements. The optimization task was divided into two parts: longitudinal compression was addressed using a surrogate model, while transverse matching is currently being pursued with Bayesian optimization.

Speaker: Jens Schaefer (Karlsruhe Institute of Technology)

16:00 Space charge in the GALACTIC Vlasov solver

The GALACTIC Vlasov solver can be used to study the impedance-induced transverse coherent instabilities, considering any longitudinal distribution function, describing the beam with transverse coherent oscillation modes in the frequency domain and ending up with an eigenvalue system to solve. In this paper, the effect of the transverse coherent direct space charge is added, considering a linear RF force and three distribution functions in the longitudinal plane: Water-Bag (or uniform), Air-Bag (or Dirac delta) and Gaussian. These three cases are then compared to the Air-Bag bunch in a Square potential well (ABS) model, which has been often used in the past.

Speaker: Elias Métral (European Organization for Nuclear Research)

16:00 Status of the CERN optics measurement and correction analysis tools

With a change in the LHC machine optics foreseen for 2025 and the possible reduction of beta-star, optics commissioning will become even more of a challenge for the CERN Optics Measurement and Correction (OMC) team. In particular, the increased sensitivity of the optics to non-linear imperfections, requiring a plethora of accurate measurements, is expected to be a time consuming task. In preparation, continuous effort has been undertaken to develop new correction strategies and convert them into ready-to-use algorithms, allowing the automation of repetitive tasks while keeping the python-base software tools up-to-date. In this paper the status of these tools is summarized with highlights and improvements underlined. These tools are now widely used beyond the LHC in the entire CERN accelerator complex, as well as in Super-KEKB and for Future Circular Collider studies, and could be of great interest to correct and improve the optics in other machines.

Speaker: Joschua Dilly (European Organization for Nuclear Research)

16:00 Studies on the large residual horizontal orbit in the SIRIUS booster

SIRIUS, the Brazilian 4th-generation synchrotron light source, operates in top-up mode at a current of 200 mA. Despite previous optimizations, the storage ring injection system still requires improvements in efficiency, to attend the tight demands in terms of repeatability and charge per pulse. In this context, this work investigates the large residual horizontal orbit distortion in the booster, that cannot be corrected with the current orbit correction system. A method to mitigate the problem, based on displacing focusing quadrupoles horizontally will be analyzed. Additionally, a hypothesis to explain the origin of the distortion, based on dipole error correlations introduced by the magnet sorting algorithm, will be investigated.

Speaker: Otávio Silveira (Brazilian Synchrotron Light Laboratory)

16:00 Study of an anomalous beam profile in the Compact ERL’s injector at KEK

The cERL injector objective is to produce and deliver a high-quality electron beam to the recirculation loop. However, a recent observation of an anomalous "triangle beam" profile just after the first solenoid presents significant challenges. This distorted beam profile can lead to inaccurate parameter measurements, reduced focusing and collimation efficiency, and increased sensitivity to injector errors.
This study investigates potential causes, including hexapole field components, misalignment, nonlinearity of air-core steering, and beam kick at cathode. Machine learning techniques are employed to analyze experimental data and simulation results to identify the primary factors. Based on these findings, potential solutions to mitigate the "triangle beam" issue and optimize injector performance are proposed.

Speaker: Olga Tanaka (High Energy Accelerator Research Organization)

16:00 SuperKEKB transport beam line in-depth characterization of multi bunch high energy electron and positron beams

After the great success of KEKB asymmetric-energy collider achieving the world highest luminosity, the ambitious upgrade SuperKEKB collider aims to take the positron-electron colliders to the next level by achieving 40 times higher luminosities. However, this represents a huge challenge, requiring of a highly precise way to control the beams to suppress emittance growth and to assure their correct injection. In order to be able to do it, first, the beams should be well characterized and understood after their passage through the LINAC. In this work, the characterization of the currently obtained beams at Super-KEKB is shown for both, the 7 GeV electron beam and the 4 GeV energy positron beam in the 1-bunch and 2-bunch configurations, from the LINAC to the entrance of the Main Ring.

Speaker: Dr Driss Oumbarek Espinos (High Energy Accelerator Research Organization)

16:00 Symmetric double-double bend lattice for a potential EUV diffraction limited upgrade of the HLS

NSRL recently proposed a future plan to further upgrade the HLS to an EUV diffraction-limited storage ring, named HLS-III. In this paper, a symmetric double-double bend lattice with long and mid-straight sections is studied as a highly promising design for the HLS-III storage ring. The design achieves an ultra-low natural emittance of 2.82 nm·rad at 800 MeV, while maintaining the current eight straight sections but with significantly reduced beta functions in these straights. By minimizing the fluctuation of resonance driving terms, the nonlinear dynamics optimization yields a large horizontal dynamic aperture of about 40 mm. Additionally, error and intra-beam scattering effects are evaluated.

Speaker: Masahito Hosaka (University of Science and Technology of China)

16:00 The stability diagram for longitudinal coupled instabilities of the ALBA upgrade

The design of the ALBA upgrade forsees the use of an active harmonic cavity system for bunch lengthening. The resulting RF-potential will be a combination of a harmonic and a quartic potential. The corresponding stability diagram will be computed and compared to the stability diagram based on a pure quartic RF-potential. It will be checked if an already existing HOM in the DAMPY cavities and a parasitic mode found in the bellows can be damped with this mechanism.
Since the radiation damping of the ALBA upgrade is rather weak the Landau damping is an asset for the stability of the upgrade.

Speaker: Thomas Günzel (ALBA Synchrotron (Spain))

16:00 Towards Improving luminosity using optics tuning and data-driven methods

The results of Run 24 experiments at Relativistic Heavy Ion Collider (RHIC) for improving luminosity using optics tuning are presented in this study. In the first experiment, MADx matching was used to output magnet strengths corresponding to specific s star movements around Interaction Region 8 (IR8). The corresponding Zero Degree Calorimeter (ZDC) signal was measured in place of luminosity, and Bayesian Optimization aids search of optimal movements. It was found that values retrieved from matching were inaccurate, resulting in negative feedback loops. The second experiment focused on calculating accurate s star movements. The matching method was replaced with a linear sensitivity matrix, directly relating optics to power supply, and its null space was used to fit constraints such as hysteresis effects. At the experiment, beam losses were observed at collimators around boundary of IR8, which were fixed for the third experiment. Dynamic mode decomposition was also introduced to improve quality of turn-by-turn (TBT) data as well as accuracy and consistency of optics measurements at IR8. These improvements will be tested in the experiment of next RHIC run for luminosity optimization.

Speaker: William Fung (Facility for Rare Isotope Beams)

16:00 Towards operational optics measurements with AC Dipole excitations in the CERN SPS

In the CERN Super Proton Synchrotron (SPS), a new AC dipole excitation functionality has been implemented with the aid of the Beam-Based Feedback and Diagnostic Systems. This feature facilitates precise and systematic optics measurements, presenting a robust alternative to the conventional single-kick excitation method. Comparative studies of AC dipole and single-kick excitations have been performed, employing linear and nonlinear optics measurements. Experimental results highlight the reliability and accuracy of the AC dipole implementation, underscoring its potential for integration in standard SPS operations for routine optics measurements.

Speaker: Michi Hostettler (European Organization for Nuclear Research)

16:00 Trajectory design for passing through solenoid magnet fringe field and method for adjusting its strongly X-Y coupled phase space for three-dimensional spiral beam injection

A three-dimensional spiral beam injection scheme has been developed to realize very precise measurement of the muon spin precession frequency in the level of sub-ppm. A 300MeV/c muon beam is injected into a precisely adjusted storage magnet of sub-ppm uniformity by applying medical MRI magnet technologies for J-PARC muon g-2/EDM experiment. A strongly X-Y coupled beam is required to deliver beam into the storage volume via strong radial fringe field volume of solenoid magnet followed by beam injection channel through iron yoke. A dedicated design work of reference trajectory and beam phase space has been made in this injection section. In this presentation, we show evaluated the tolerance for the accuracy of the reference trajectory and the orbital position dependence of the required X-Y coupling parameters and discuss the required accuracy of the transport line placed upstream of the beam-line which includes eight rotating quadrupoles on the 10m of beam transport line*. Additionally, a pair of dedicated magnets called active shield steering magnet will be set at the entrance and the exit of the beam channel to perform orbital correction of the reference trajectory.

Speaker: Hiromi Iinuma (Ibaraki University)

16:00 Transverse coherent direct space charge: comparison between several approaches

The proton driver of a future Muon Collider complex is designed to deliver a multi-GeV, short and high-intensity proton bunch to a target in order to maximize the muon yield. In the International Muon Collider Collaboration (IMCC), two high power H- Linac configurations are studied: a 2 MW with a beam energy of 5 GeV, and a 4 MW with a beam energy of 10 GeV. The Linac is followed by an accumulator ring and a compressor ring. With a single bunch intensity of 5.0e14 protons within a transverse emittance of ~15 mm mrad, strong space-charge effects can be expected in these rings.
In this framework, different simulation codes used to estimate the transverse coherent space-charge mode frequency shifts in synchrotrons have been compared: BimBim, based on the Circulant Matrix Model (CMM); the Effective impedance method for space-charge; GALACTIC based on the Vlasov equation; the boxcar model for space-charge only; and the ABS model which assumes an Air-Bag bunch distribution in a Square well.

Speaker: Elias Métral (European Organization for Nuclear Research)

16:00 Transverse mode-coupling instability with Landau cavities at the MAX IV laboratory 1.5 GeV ring

Collective effects can have a strong influence on the beam stability and performance in synchrotron light sources. Landau cavities or RF harmonic cavities are a tool that is employed at 4th generation storage ring light sources to reduce the impact of or even prevent instabilities arising from collective effects. The positive effect of Landau cavities is based on the lengthening of the electron bunches and an increase in synchrotron tune spread. Recent theoretical calculations by M. Venturini (2018) predict however, that at zero chromaticity, the threshold current of the transverse mode-coupling instability (TMCI) was reduced in the presence of Landau cavities.
This contribution presents measurements conducted at the MAX IV 1.5 GeV storage ring, where, to test the prediction, the TMCI threshold was measured with and without bunch-lengthening using passive Landau cavities. The effect at non-zero chromaticity was also investigated.

Speaker: Miriam Brosi (MAX IV Laboratory)

16:00 Updated single-bunch instability threshold measurements in Diamond

This work presents the results of single-bunch-instability measurements in the Diamond storage ring. A streak camera was used to measure the bunch lengthening with current, whilst transverse multi-bunch feedback (TMBF) was utilised to quantify the charge-dependent betatron tune shifts and the head-tail instability thresholds. The results show that increasing chromaticity can be used to mitigate head-tail instabilities which can allow to accumulate higher charge in a single bunch. Using TMBF to suppress single-bunch instabilities is discussed.

Speaker: Ian Martin (Diamond Light Source)

16:00 Xnlbd: A new Python package for the analysis of non-linear beam dynamics phenomena

Nonlinear effects in particle accelerators have historically been treated as harmful influences that necessitate various mitigation schemes. Therefore, the simulation tools available are largely focused on identifying and correcting resonances. However, recent advances proved that nonlinear beam dynamics enables new techniques for manipulating particle beams and can characterise diffusion and chaos in particle accelerators. The simulation tools currently available for these purposes are difficult to integrate across different frameworks. This paper presents Xnlbd, a new Python package extending the Xsuite simulation framework, which aims to provide a unified set of tools for analysing nonlinear beam dynamics phenomena. It allows the visualisation of highly nonlinear phase spaces, the efficient finding of both stable and unstable fixed points and separatrices, the calculation of resonance driving terms and normal forms, and the computation of dynamic indicators for the detection of chaotic motion.

Speaker: Dora Veres (European Organization for Nuclear Research)

16:00 → 18:00 Wednesday Poster Session: WEPS

16:00 A new method for the RFQ inter-vane voltage diagnostic

Radio frequency quadrupole (RFQ) is one of the first cavities in a protons or ions accelerator. It aims to focus, bunch, and accelerate the beam, using a high-intensity electric field concentrated between rods or vanes. At CEA, similarly to other labs, a method to evaluate the inter-vane voltage and to tune the cavity (usually with 4 vanes) has been developed, based on the bead pull measurement. It consists of inserting a small bead in the back of each of the 4 quadrants. The induced magnetic field perturbation aims to evaluate the electric field close to the beam axis. This method requires the insertion of a bead along the cavity, whose length can be about several meters. In this paper, we propose to study the possibility of measuring and tuning the cavity using the insertion of slug tuners which would demonstrate the feasibility of obtaining this diagnostic, without opening the cavity.

Speaker: Pierrick Hamel (Commissariat à l'Energie Atomique)

16:00 Achieving diverse beam modes with modelling and optimisation for the versatile SRF photoelectron gun at SEALab

The SEALab facility in Berlin is home to an R\&D superconducting radio-frequency (SRF)photoinjector setup and beamline. Designed to support multiple varied applications - ranging from Energy Recovery Linac (ERL) to Ultrafast Electron Diffraction (UED) and Electron-Beam Water Treatment (EBWT) - SEALab requires flexible, high-precision tuning to support these diverse beam modes. These applications span over three orders of magnitude in bunch charge, emittance, and current, alongside sub-picosecond pulse lengths. This makes injector setup and tuning a significant challenge. With the world's first beam achieved at SEALab from a Na-K-Sb cathode in our SRF gun, a suite of beam dynamics models has been developed to support understanding of the beam behaviours in the gun, where no observations are possible, and operation of the commissioning process. This is comprised of a first-order analytical model, particle-in-cell (PIC) ASTRA simulations, and a machine-learning surrogate model trained for current commissioning operation ranges. These models are coupled with a Multi-Objective Bayesian Optimisation (MOBO) algorithm to enable rapid tuning across multiple beam modes. This combination of surrogate modelling and optimisation algorithm reduces optimisation timescales from hundreds of hours to minutes, allowing near-real-time tuning for the accelerator. This work presents the modelling framework, its validation, and its application to SEALab's many-mode optimisation challenges.

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

16:00 Advancing beam dynamics for high current cyclotrons

This study explores beam dynamics in the development of high intensity cyclotrons, focusing on the challenges posed by space charge effects at high beam intensities. Space charge forces, which become significant in high-current operations, can lead to emittance growth, beam loss, and instability, compromising cyclotron performance. Advanced modeling techniques are employed to analyze and mitigate these effects, ensuring stable beam transport and acceleration throughout the cyclotron. By optimizing field configurations and beam trajectories, the study achieves improved beam quality and reduced particle losses. These findings contribute to the development of cyclotrons capable of delivering high-intensity beams for applications such as BNCT.

Speaker: Chong Shik Park (Korea University Sejong Campus)

16:00 An electron beam manipulated by circularly polarized Laguerre-Gaussian modes

Manipulation of an electron beam by Laguerre-Gaussian (LG) modes is investigated using finite-difference time-domain particle-in-cell (FDTD-PIC) simulations. The azimuthal velocity profiles of macro-particles exhibit a 3-D spiral pattern with the number of strands equal to a sum of the state number of spin angular momentum and the orbital angular momentum of LG modes. These spiral patterns move along with the electron beam like a helical traveling wave. The electrons also exhibit both an orbit revolution and a small rotation motion. The former is very similar to the gyromotion of electrons under an external magnetic field. The small rotation motion has the same frequency as that of the LG mode while the orbit revolution frequency or gyrofrequency is far lower. This gyrofrequency can be manipulated by the frequency, electric field strength, and beam waist size of the LG mode. Furthermore, a larger-current electron beam can be confined within the LG mode by increasing the electric field strength. It is demonstrated that the manipulation of an electron beam can be realized by using circularly polarized LG modes. The fundamental mechanism and simulation results will be presented.

Speaker: M.C. Lin (Hanyang University)

16:00 An updated HL-LHC halo population model based on recent experimental measurements

The transverse beam halo population in the Large Hadron Collider (LHC) has been found to carry a significant fraction of the total stored beam energy, potentially reaching several percent. With the anticipated increase in beam brightness for the High Luminosity LHC (HL-LHC), this poses an increasing risk to machine safety, particularly during abrupt orbit shifts or critical component failures. A comprehensive understanding and an accurate modelling of the transverse beam halo are crucial for simulations of beam losses around the ring as a consequence of such failure scenarios in the HL-LHC era. Various models, including Gaussian, double-Gaussian, and q-Gaussian distributions, have been used to describe the LHC beam halos for fitting the measured distributions. This paper provides an in-depth analysis of halo modelling based on collimator scraping measurements from the LHC operational Run 2 and Run 3, and evaluates the accuracy and representativeness of these different distribution models.

Speaker: Pascal Hermes (European Organization for Nuclear Research)

16:00 Analysis of coupled-bunch instabilities in Diamond-II

The low-frequency components of the impedance drive coupled-bunch instabilities in electron synchrotrons. In the Diamond-II storage ring, the geometric component of the impedance of some vacuum vessels is comparable in strength to the resistive-wall impedance. This study compares the growth rates of all coupled-bunch modes obtained through simulations and analytical calculations. Self-consistent simulations, incorporating the harmonic cavity along with short-range wakefields and higher-order cavity modes, show that the beam can be stabilised with and without multi-bunch feedback by adjusting the chromaticity.

Speaker: Ian Martin (Diamond Light Source)

16:00 Analysis of higher order modes of QWR cavity for in-situ plasma processing

SRF cavities deteriorate in efficiency over time and need for inexpensive cleaning methods that are effective is apparent. Plasma Processing is one such cleaning method that can be implemented in-situ, reducing the processing time taken drastically. In this work we present our analysis of the higher order modes of the 72 MHz QWR at ATLAS, ANL for use in igniting plasma for cavity processing.

16:00 Application of the nonlinear material solver in the ACE3P electromagnetic code suite

SLAC has been developing the parallel finite element electromagnetics simulation suite ACE3P (Advanced Computational Electromagnetics 3D Parallel) for accelerator modeling using high performance computing (HPC) platforms. In this work we present the current status of the development of the nonlinear EM solver, in ACE3P which includes nonlinear material with application to quantum nonlinear photonics. This utilizes parallel and scalable architecture to perform simulations on multiscale optical and quantum systems. We show examples of harmonic generation, and parametric interaction essential for THz generation. Also we show examples of using this code to design novel THz nonlinear deflecting structures used for developing a sub0femotosecon timing diagnostics for UED beamlines.

Speaker: Mohamed Othman (SLAC National Accelerator Laboratory)

16:00 Atomic layer deposited ZnMgO multilayered coatings for TEEY and electrical conductivity optimization

Total electron emission yield (TEEY), defined as the number of electrons emitted per incident electron of a given energy, is potentially the source of two major problems: electrostatic discharges (ESD) in vacuum and multipacting effect. To mitigate these risks, a possible solution could be to coat the surfaces prone to ESD or multipacting originate with a thin film with tunable TEEY and electrical conductivity. In order to be able to control both properties independently, a possible solution is to develop a thin film heterostructure based on the mixing of a low TEEY, electrical conductor material with a high TEEY, dielectric material in order, for instance, to obtain a low TEEY, dielectric coating that will prevent both Multipacting and a decrease of surface losses quality factor. We choose the Atomic Layer Deposition (ALD) method to achieve that goal and we will present results obtained with coatings made of multiple layers of ZnO and MgO to verify that this solution is relevant. Electrical conductivity and TEEY measurements carried out on these multimaterial multilayered coatings have shown that both properties vary according to their composition and their structure.

Speaker: Mathieu Lafarie (The French Aerospace lab)

16:00 AtomicAndPhysicalConstants.jl – a package for managing physical constants atomic and subatomic data in Julia

AtomicAndPhysicalConstants.jl is a Julia package designed to provide atomic and physical constants including the speed of light, subatomic particle properties, atomic isotope properties, etc. Values are obtained from CODATA (Committee on Data of the International Science Council), NIST (National Institute of Standards and Technology), and PDG (Particle Data Group) datasets for physical constants, atomic and subatomic particles for scientific computations, particularly in fields such as particle and accelerator physics. Key features include a macro for users to access and customize units for constants, dynamic updates to integrate the latest scientific data, and compatibility with Julia's Unitful.jl library for convenient unit manipulation. These capabilities make the package ideal for applications requiring rigorous physical accuracy and reproducibility.

Speaker: Lixing Li (Cornell University)

16:00 Beam Dynamic study of the accelerating cavity of the dual energy NSTRI-eLinac

The side-coupled standing wave accelerator tubes have a wide range of applications in linear electron accelerators due to their relatively high acceleration gradient and relatively low sensitivity to manufacturing errors. In the NSTRI-eLinac project, a dual energy electron linear accelerator is defined for cargo applications. In this accelerator, a side-coupled standing wave tube accelerates electrons to energies of 4 and 6 MeV. This tube operates at a frequency of 2998.5 MHz in the π/2 mode, fed by a magnetron with a maximum power of 2.6 MW. The most important issue in designing the accelerating tube is the interaction between the electron beam and the RF electromagnetic field to deliver the electron bunch at the desired energy with maximum efficiency and suitable output beam quality. Beam dynamics studies are essential for determining the specifications of the output beam. In this paper, the output beam characteristics for the NSTRI accelerating tube have been investigated using the STRA code. The results estimate the output beam characteristics in energies of 4 and 6 MeV at the end of the constructed tube.

Speaker: maryam hashemnejhad (K.N.Toosi University of Technology)

16:00 Beam loss simulations with space charge and octupoles for the SIS100 magnet quality assessment

The components of the SIS100 synchrotron (FAIR facility) are presently under installation in the accelerator tunnel. The superconducting dipole magnets have been produced and the magnet field errors up to 7th order have been measured for all magnets. The superconducting quadrupole magnets are under production, the field error data for a part of the magnets is available. As a part of the magnet quality assessment, the particle tracking simulations are used to study the beam losses during the 1 sec beam accumulation at the injection energy. The tune settings for the slow extraction operation are considered. Direct space-charge effects and the Landau damping octupole magnets, which dominate the incoherent tune distribution, are included. In order to reduce the computational load and to increase the parameter resolution, a machine learning based optimizer is used in the accelerator and beam parameter studies.

Speaker: Vladimir Kornilov (GSI Helmholtz Centre for Heavy Ion Research)

16:00 Beam-beam simulation with lattice and related researches of STCF

To achieve the design luminosity of $1 \times 10^{35}\ \text{cm}^{-2}\text{s}^{-1}$, the Super Tau-Charm Facility (STCF) adopts an extremely low $\beta_y^*$ and a crab waist (CW) collision design. The extremely small vertical beam size at the interaction point and low vertical emittance required to achieve a beam-beam parameter of around 0.1 make the CW colliders highly susceptible to beam instabilities arising from beam-beam interactions. Some of these instabilities need to be carefully assessed and optimized through strong-strong beam-beam simulations. The nonlinearity from lattice will further increase the need to circumvent these instabilities.In this paper, we investigate the luminosity stability of the STCF design parameters using strong-strong simulations with lattice. We also explore the influence of the CW scheme and various beam parameters on luminosity. These findings offer valuable insight to guide lattice design and optimize global parameters for STCF.

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

16:00 Benchmark study of transverse instability driven by the resistive wall impedance in the PF-HLS 2.5 GeV storage ring

Effect of the transverse instability driven by the resistive wall impedance in the PF-HLS (Photon Factory Hybrid Light Source) 2.5GeV storage ring are investigated and compared with three methods: an analytical method with azimuthal modes, a Vlasov solver DELPHI and beam tracking code MBTRACK2**.
The PF-HLS is proposed as the successor machine to the PF-2.5GeV ring and the PF Advanced Ring at KEK. Its concept is a 2.5/5.0GeV energy switchable high-brightness storage ring with a circumference of 750m. A feature of this ring is the adoption of isochronous cells over a large part of the ring, which allow electrons having a bunch length shorter than one nano-second to pass through without significant bunch lengthening. However, in return for this feature, the momentum compaction factor becomes small, which is estimated to 3.24x10-5. In this case, the coherent beam motion may be sensitive to the ring chromaticity.
As the results, it's suggested that the higher-order modes of the coherent beam motion determine the stability of the beam. In the paper, the chromaticity dependence of the instability growth rate for each method is compared and reported in detail.

Speaker: Norio Nakamura (High Energy Accelerator Research Organization)

16:00 Benchmarking Intrabeam Scattering with RF-Track

Intra-beam scattering (IBS) has recently gained significant interest in the community of free electron lasers (FELs), as it is believed to produce an increment in the sliced energy spread (SES), which is detrimental to FEL performance. To control and contain this phenomenon, it is important to include IBS in the design phase of an FEL through appropriate numerical simulation. Most existing codes that simulate IBS were developed for long-term tracking in circular lattices, assuming Gaussian bunches. Unfortunately, this assumption doesn’t capture the rapid bunch evolution of electron bunches in photoinjectors. To address this limitation, the tracking code RF-Track has recently been updated to include IBS, using a novel hybrid-kinetic Monte Carlo method.
This paper presents benchmarks performed to verify the implementation. The predicted SES increment in the beam due to IBS using RF-Track has been compared against a kinetic approach used in a different tracking code and, secondly, against a semi-analytical model. The results showed a good agreement, setting RF-Track as a tool to understand and control the SES growth in photoinjectors and, in particular, in FEL.

Speaker: Paula Desire Valdor (European Organization for Nuclear Research)

16:00 Bunch length regulation in the LHC during controlled emittance blow-up

Controlled longitudinal emittance blow-up is indispensable for the operation of the Large Hadron Collider (LHC) to counteract single-bunch loss of Landau damping during the acceleration ramp. The blow-up is performed by injecting RF phase noise in a narrow frequency band into the beam phase loop, with bunch-length feedback regulating the noise amplitude. In 2024, the variation of the bunch length due to imperfect regulation caused unacceptable beam-induced heating of certain accelerator components. In this contribution, we present the results of extensive simulation scans that have been used to optimize the feedback parameters. We show how this optimization, along with a reduction of the feedback delay on the controls side, has been implemented in the LHC and significantly improved the bunch length evolution during acceleration. Finally, we discuss the results of a measurement scan performed during an operational period of five weeks to fine-tune the blow-up feedback settings.

Speaker: Niki Gallou (European Organization for Nuclear Research)

16:00 Characterizing proton beam properties for cell irradiation study using GEANT4 simulation

The purpose of this research is to characterize proton beam properties - beam energy, energy spread, beam size, and transverse emittance - to establish the initial setup for simulation in planning cancer cell culture experiments at the Cyclotron Medical Accelerator at King Chulalongkorn Memorial Hospital in Bangkok, Thailand. The characterization was performed using GEANT4 Monte Carlo (MC) simulations. Proton energies of 70 MeV, 100 MeV, 150 MeV, and 220 MeV were selected, and the 80%-20% distal fall-off of the depth profile was utilized to determine the energy spread. The simulated results were then verified against experimental data and compared with the Treatment Planning System (TPS). The details of the validating procedure, as well as results on the optimized energy spread, beam size, and emittance, and the irradiated setup for cell irradiation, will be discussed in this contribution.

Speaker: Kritsada Kittimanapun (Synchrotron Light Research Institute)

16:00 Coherent synchrotron radiation instability in steady-state microbunching ring

We study the coherent synchrotron radiation instability in a novel synchrotron light source concept, steady-state microbunching storage ring.

Speaker: Zhuoyuan Liu (Tsinghua University)

16:00 Design and implementation of ridge waveguides for dual-mode microwave structure

The growing interest in dual-mode microwave structures has led to a surge in research efforts. A critical challenge in their application is the efficient transfer of microwave power with various frequencies. One approach to this issue involves the utilization of intricate waveguide components, such as a dual-mode electron gun that operates at both the fundamental and second harmonic frequencies. This gun is constructed by integrating a directional coupler with a mode launcher, which allows the S-band and C-band power to be transferred into a single waveguide, directing them to a dual-mode electron gun. An alternative method employs ridge waveguide technology to selectively transmit or block specific frequencies. The technology has been successfully integrated into dual-mode deflecting structure. This paper presents a C-band bandpass filter has been engineered to achieve a power reflection level of less than -30 dB at 5712 MHz and a power transmission level of less than -40 dB at 11424 MHz.

16:00 Design and simulation of high-power RF window for NSTRI e-Linac Project

The RF window has to withstand several megawatts of RF power without experiencing any physical deformity to maintain the pressure difference between vacuum and isolate gas sides. It must also have suitable and acceptable RF performance with minimum reflection and insertion loss. The design of an RF window depends on the window materials' dielectric characteristics, such as dielectric constant, permeability, and permittivity. The dielectric permittivity and permeability of window material affect the transmission of RF power.
This paper presents the design and simulation of an RF window that works at a frequency of 2.998 MHz and performs thermal analyses to determine its structural stability. This RF window must withstand an average power of 3 kW. This window will used for NSTRI dual energy e-Linac Project.

Speaker: Sara Zarei (Nuclear Science and Technology Research Institute)

16:00 Design of a high-power X-band load with circular waveguide TE01 mode input

RF loads are critical components in any high-power rf system. There are two types of commonly used rf loads in multi-megawatt systems: water loads and dry loads. Water loads have a ceramic window separating vacuum from the water. Use of water loads in large scale rf systems is risky because of the possibility of water leaking into vacuum. At SLAC multi-megawatt dry loads were developed and used in S-band and X-Band applications. For example, a compact X-band load based on a tapered WR90 and circularly polarized TE11 mode has been in use for decades. To increase high power performance of a load beyond the state-of-the art, we designed an 11.424 GHz load fed by the TE01 circular waveguide mode. The load is of disk-loaded-waveguide type, built out of a set of cells. The cells are made of magnetic stainless-steel with bulk conductivity is 160000 S/m. The passband of the load is about 180 MHz. The load utilizes axially symmetric TE mode which has minimal surface electric fields. We show the design of the load and results of X-band resonant measurements of the load’s cells. The measurements allow us to determine conductivity of the 430 stainless steels after multiple brazing cycles.

Speaker: Mohamed Othman (SLAC National Accelerator Laboratory)

16:00 Design of High Gradient, Fast Response, Broadband RF System for HIAF

The high broadband field-gradient RF system based on direct oil-cooling magnetic alloy cavity for High Intensity Heavy-ion Accelerator Facility (HIAF) Bost Ring (BRing) has been successfully reached and developed in Oct. 2022. The RF system consists of a three gaps cavity which loaded by 24 domestic nanocrystalline soft magnetic alloy (MA) ring cores, a RF power amplifier with an output power of 500 kW and digital LLRF. The acceleration voltage reached 66kV (gradient > 30kV/m) with a frequency swing from 290kHz to 2.1MHz, amplitude stability |△A/A|≤1% and phase stability |△φ|≤ 1°.
In 2011, we collaborated with Chinese companies to begin the R&D of ultra-thin amorphous metal ribbon and magnetic ring core manufacturing process, in the meanwhile also established a MA core test platform. After ten years’ effort, 780(OD)×350(ID)×35 (TH) mm MA core with broadband characteristics in the frequency range of 0.1MHz to 20MHz has been successfully developed using domestic 14μm ribbon in 2021. The key performance μQf and Q at 0.3MHz are 6.5GHz and 0.9, respectively.
In addtion, in order to further improve the acceleration gradient, we are still working hard to enhance the performance of MA core.

Speaker: Peng Jin (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Design of non-linear kicker for Siam Photon Source II

A non-linear kicker (NLK) is designed for the beam injection into the storage ring of Siam Photon Source II. The required deflection angle is 4 mrad, the effective length is 400 mm and the peak field is 100 mT at the horizontal position of 9 mm from the magnet center. The design is based on 8-wire configuration where the conductor position is symmetric along the xz and yz planes. The vertical size of ceramics chamber is determined by the vertical beam stay-clear at the magnet position, available space for magnet installation and feasibility of conductive coating process. Magnetic field calculation of the NLK is performed in Radia and Opera-3D. The octupole-like magnetic field with the field-free region at the magnet center minimizes perturbation on the stored beam. Nevertheless, position error of the conductors leads to excess dipole and quadrupole field components at the magnet center. Magnetic field distortion is also caused by Eddy current induced in the conductive coating in transient analysis. In this work, magnetic design and magnetic field calculation of the NLK is presented.

Speaker: Prapaiwan Sunwong (Synchrotron Light Research Institute)

16:00 Design, manufacturing and validation of fast-ramping alpha magnet for interleaving operation at ANL APS

RadiaBeam has designed and manufactured a fast-ramping alpha magnet (FRAM) that is developed for interleaved operation at the Advanced Photon Source (APS) at Argonne National Laboratory. This interleaving operation requires the alpha magnet to stably complete a 5 s long cycle with a 100 ms ramp-up, 1s nominal field output and a 100 ms ramp-down. A laminated yoke is used to minimize eddy currents, ensure fast field response times and reduce core-loss during operation. The magnet has been measured by a Hall probe at Radiabeam and at Argonne, demonstrating 2.75 T/m maximum field gradi-ent within a 10 cm x 14 cm good field region in both DC and pulse modes.

Speaker: Yung-Chuan Chen (RadiaBeam Technologies (United States))

16:00 Development and application of high-performance MA core

From 2010, the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS) carried out the relevant testing and research work on the RF Cavity loaded magnetic alloy materials firstly, and explored the development process of high-performance magnetic alloy (MA) cores with domestic manufacturers and research institutes jointly. Through the long-term exploration from small (diameter≤100mm), medium (diameter≤460mm) to large (diameter ≤ 1000mm) high-performance MA cores, breakthroughs have been made in many key processes, such as MA ribbon shearing, insulation silica coating, horizontal winding, atmosphere annealing and epoxy resin proof coating etc. Finally, liquid-cooled MA cores with high performances and large sizes were developed successfully. Its performance parameter value of μ'pQf is more than 30% higher than that of the same type of optimal MA cores, reported publicly in the world. Moreover, it reached the international advanced levels and realized the localization replacements. Meanwhile, the Institute of modern physics built a high-performance MA core production line with independent intellectual properties together with domestic enterprises. This realized the batch productions in high-performance MA cores. At present, the high-performance MA cores from this production lines were successfully applied in many projects

Speaker: Peng Jin (Institute of Modern Physics, Chinese Academy of Sciences)

16:00 Development of an online adjustable waveguide coupler for CSNS- Ⅱ debuncher cavity

The China Spallation Neutron Source Upgrade Project (CSNS-Ⅱ) will use two debuncher cavities to supplement the beam energy at the end of the linear accelerator. The PI mode structure operating at room temperature is chosen, and each debuncher cavity is equipped with an online adjustable waveguide coupler. The main body of the coupler is the WR1500 waveguide, and a hole on the narrow wall of the waveguide is opened to achieve the coupling between the cavity and the waveguide. Meanwhile, every coupler contains a removable waveguide window. In this paper, we will detail describe the electromagnetic, cooling and mechanical design of the coupler. Finally, the coupler is high-power conditioned to 1 MW with a duty factor of 2.25%, and the coupler factor of it can be online adjusted between 0.6˜3 without arc event.

Speaker: MengXu Fan (Institute of High Energy Physics)

16:00 Development of C-band compact accelerating structure made of longitudinally-split two halves

Our 6 MeV medical C-band accelerating structure is assembled 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 nunber of components, there are challenges in manufacturing efficiency. On the other hand, the longitudinally-split method divides the structure along a plane passing through the beam axis, independent of the number of cells, which significantly reduces the number of components. Based on the longitudinally-split X-band accelerating structure developed in the CLIC project, we have been working on the development of a compact, high-gradient, high-shunt impedance, longitudinally-split SC-type C-band accelerating structure. In this presentation, we will report the progress of our work, including manufacturing, RF testing, frequency tuning, and beam testing in the actual operating conditions.

Speaker: MASASHI KIMURA (Mitsubishi Heavy Industries Machinery Systems, Ltd.)

16:00 Development of high-power RF components for an X-band transverse deflector system at SACLA

We have been developing an X-band transverse deflector system (XB-TDS) with sub-fs time resolution, which will be installed after the undulator sections at SACLA. A sub-fs XFEL pulse is desirable for user experiments such as the measurements of structural disordering in an XFEL interaction with a matter, as the degree of damage depends on the pulse duration. The demand for a shorter and shorter XFEL pulse is increasing. The SACLA’s XFEL pulse duration is 6 fs at FWHM. In order to achieve a shorter XFEL pulse duration and to satisfy users’ needs, a diagnostic system of the longitudinal bunch distribution is essential. We adopt an X-band frequency to efficiently deflect an 8 GeV electron beam. We feed 20 MW to the pulse compressor, and the peak power is increased to around 100 MW, which is divided into four cavities, generating HEM11 horizontal mode. We utilize a dipole magnet before the beam dump to measure the energy-time distribution.The current status is to manufacture high-power RF components such as deflector cavity, pulse compressor, and dummy load. In this presentation, we will show the design, manufacturing method, and commissioning status of these components.

Speaker: Kenji Yasutome (RIKEN SPring-8 Center)

16:00 Development of stretched wire system for magnetic field measurement of magnets for Siam Photon Source II

A stretched wire measurement system was developed for magnetic field measurement of magnet prototype for Siam Photon Source II. It is used for magnetic field integral measurement for characterization of multipole field errors, magnet centering and fiducialization of multipole magnets. The wire trajectory across magnet aperture can be either linear or circular. The maximum wire movement is ±100 mm in both horizontal and vertical directions with the positioning accuracy of ±2 µm. The system is built on a 3.2-m granite support which allows the maximum magnet length of 2.2 m and magnet weight of 2,500 kg to be measured. Effects of wire tension, scan region, pause time between measurements, wire movement speed, number of repeated measurements and number of data points have been studied. With the optimized measurement parameters, the repeatability of 3E-4 or better can be achieved for the normalized multipole components measured using the circular scan.

Speaker: Prapaiwan Sunwong (Synchrotron Light Research Institute)

16:00 Development of test bench for 324 MHz superconducting cavity power couplers

The power coupler is one of the most important components for superconducting cavities. Different from the normal conducting cavity, the superconducting cavity has to keep an ultra-high cleanliness environment for operation. As the vacuum barrier, power couplers are welded by many different materials and maybe the gas source since they are installed to the cavities after vertical test, therefore, they should be high power conditioned before operation. Generally speaking, test bench equipment with two power couplers is often designed to improve the high conditioning efficiency. In this paper, different types of test benches are compared according to simulation and the cylindrical quarter-wavelength cavity is chosen. Besides, the detailed electromagnetic and mechanical design of the test bench is presented; to verify machining accuracy, two test pieces are also designed to measure the transmission of the test bench. Finally, limited by the output power of klystron, the test bench with a pair of couplers is high power conditioned to a standing power level of 500 kW with a repetition rate of 25 Hz and a pulse width of 1.2 ms.

Speaker: MengXu Fan (Institute of High Energy Physics)

16:00 Dynamic simulation of collective physics in SSMB storage ring

We simulated the dynamic problems in the SSMB storage ring, such as TMCI, through the dynamic simulation software elegant and discovered its instability threshold current intensity.

Speaker: Mr Jiazhen Tang (Tsinghua University)

16:00 Dynamics studies for advanced-compact and high repetition rate C-band injector for PWFA

C-band technology holds the potential to generate a high-energy, high-brightness electron beam by elevating the peak field of both the cathode and cavity within the machine. This proposed injector offers a promising avenue for achieving kHz operation. The conceptualization of this injector draws inspiration from the EuPRAXIA@SPARC_LAB S-band injector, wherein the gun is replaced with a 2.6-cell C-band RF gun. The entire beamline is proportionally scaled, reducing lengths by a factor of 2 while doubling electric and magnetic fields. Operating with brief RF pulses, the 2.6-cell C-band RF gun mitigates breakdown rates and power dissipation. By capitalizing on higher peak fields and applying established scaling laws to reduce laser spot size and duration, it becomes feasible to minimize both cathode and space charge emittance. A Ka-band HHC after the RF gun stabilizes the beam by pre-correcting its longitudinal phase space, flattening the charge distribution, and optimizing parameters at the photoinjector exit. The design of a C-band injector is within the framework of the EuPRAXIA@SPARC_LAB design study, aiming to produce high-quality beams for PWFA applications.

Speaker: Gilles Jacopo Silvi (Istituto Nazionale di Fisica Nucleare)

16:00 Effects of chromaticity and space charge on coupled bunch instability in CSNS/RCS

Coupled bunch instability was observed during beam commissioning of CSNS/RCS. The instability was successfully suppressed by installing sextupoles to control chromaticity. The instability exhibits characteristics influenced by the strength of space charge. We conducted a theoretical study on the effects of chromaticity and space charge on coupled bunch instability and compared results with simulation and measurements. This work provides valuable insights for beam control in the second phase of CSNS.

Speaker: Li Rao (Institute of High Energy Physics)

16:00 Effects of dark current in high brightness RF photoguns

The behavior of high gradient rf cavity is improved via the reduction of RF breakdown rates by operating at cryogenic and temperatures. These studies are largely empirical but they present a new paradigm in the future of high gradient capital operation. Peak electric fields >200 MV/m are sustainable at S and C band frequencies. These fields while sustainable produce more dark current than is ideal for high brightness beam production. We present investigation into the dark current limits on high brightness beam performance, especially in the case of an RF photogun where beam dynamics is most sensitive. We also present mechanism for reducing the effects of dark current on bright low charge electron beams produced in high gradient photoguns. Specific interest is spent considering reentrant nosecone geometric for high shunt impedance cavities.

Speaker: Gerard Lawler (University of California, Los Angeles)

16:00 Electron cloud mitigation techniques for the FCC-ee

The Future Circular Collider (FCC)-ee is a planned electron-positron collider under development. The future collider would be built in an about 91 km ring-shaped underground tunnel located beneath the French departments of Haute-Savoie and Ain, and the Swiss canton of Geneva. The FCC-ee may face challenges from electron cloud (e-cloud). The strongest effects are foreseen for the Z configuration, due to the highest number of bunches, which corresponds to the smallest bunch spacing, which is a key parameter for the e-cloud formation process. A high electron density in the beam pipe could limit the accelerator’s achievable performance through various mechanisms, such as transverse instabilities, transverse emittance growth, particle losses, vacuum degradation and additional heat loads on the inner surface of the vacuum chambers. In the design phase, the objective is to suppress the e-cloud effects in the FCC-ee. Therefore, effective e-cloud mitigation techniques, to avoid the e-cloud avalanche multiplication and its deleterious effects, are discussed in the paper.

Speaker: Dr Luca Sabato (École Polytechnique Fédérale de Lausanne)

16:00 Enhanced G4beamline advanced GUI for accelerator modeling

Graphical user interfaces (GUIs) are sought to support particle accelerator and beamline modeling for both conventional and advanced accelerator concepts. Downloaded over 1500 times in the last 22 years, G4beamline (available gratis from Muons, Inc.) has been used for diverse applications in science and industry, representing over 50M$ of economic activity. Its strengths include ease of use compared to its underlying CERN Geant4 package, flexibility in modeling beamline elements (as well as other systems such as particle detectors), and use of the well tested Geant4 libraries to track particles in electromagnetic fields and in matter: of particular importance in simulating muon cooling and muon colliders. Its current GUI interface is however rudimentary. A more comprehensive and modern GUI would enhance the program’s utility and user appeal, attracting a wider community of users in accelerator science and related fields. Another valuable feature would be “hooks” in the GUI interface for additional commonly used simulation programs such as MCNP and MAD-X, easing comparisons among alternative accelerator modeling tools by providing a common geometry description and output format.

Speaker: Daniel Kaplan (Illinois Institute of Technology)

16:00 Error tolerances for a 4 GeV fourth-generation synchrotron light source

Recently, many new light source projects have been developed based on the Multi-Bend Achromat (MBA) magnet lattice. In general, the dynamic aperture and transverse emittance of synchrotron light sources are sensitive to errors in magnet fields, alignment, and momentum. A realistic estimation of error tolerances is crucial for the successful construction of a fourth-generation synchrotron light source. In this paper, we present a realistic estimation of the error tolerances for a 4 GeV, 800-meter-long fourth-generation synchrotron light source, based on numerous simulations performed using the ELEGANT code in conjunction with an MCP server and an Agentic AI.

Speakers: Changbum Kim (Pohang Accelerator Laboratory), Yujong Kim (Korea Atomic Energy Research Institute)

16:00 Estimation of coupled-bunch instability induced by high-order modes of bell-shaped cavity in high current operation at SPring-8-II

At the large synchrotron radiation facility SPring-8, the upgrade project “SPring-8-II” is underway to increase the radiation brightness by 100 times. In SPring-8-II, the beam energy will be reduced from 8 GeV to 6 GeV and the beam current will increase from 100 mA to 200 mA. The bell-shaped 509 MHz cavities will remain in place at SPring-8-II, with the number of cavities reduced from 32 to 16. Currently, the longitudinal coupled-bunch instability (CBI) is not observed. However, the CBI may occur due to high-order modes (HOMs) in some cavities because of the parameter changing at SPring-8-II. We estimated the threshold shunt impedance and Q-value for the CBI by using Ansys HFSS. Especially, TM011 mode at 900 MHz has a large impedance and the threshold impedance is 0.8 MΩ, which corresponds to QL~12,000 when R/Q=65Ω. On the other hand, we measured the actual QL-value of the cavities using single-bunch beam. The spectra and its Q-values of the HOM induced by the beam were measured. The results show that most cavities are below the threshold, but some cavities are over threshold. If the HOM causes instability, we plan to adjust two tuner plungers to shift them off the peak.

Speaker: Takato Tomai (Japan Synchrotron Radiation Research Institute)

16:00 Estimation of the required current on the anode power supply for high power operation in the J-PARC Main Ring

The J-PARC Main Ring (MR) RF system has been undergoing upgrades in preparation for the Hyper-Kamiokande (Hyper-K) neutrino experiment, which is scheduled to begin receiving a 1.3 MW proton beam in 2028. The beam will be accelerated from 3 GeV to 30 GeV within the MR over a reduced cycle time of 0.58 seconds, down from the current 0.65 seconds. Additionally, the number of protons will be increased from $2.3 \times 10^{14}$ to $3.1 \times 10^{14}$to support high power operation. To accommodate these enhancements, additional RF cavities equipped with 600 kW vacuum tubes will be installed, and the anode current will be increased accordingly. Maintaining a constant RF voltage under these conditions requires more anode current to supply the necessary voltage and to compensate for beam loading effects. This paper presents an estimation of the anode current required for high-power beam operation.

Speaker: Kiyomi Seiya (High Energy Accelerator Research Organization)

16:00 Experimental investigation of longitudinal scraping of H- bunches via photo-detachment

Longitudinal emittance growth is a significant challenge in RF linacs, especially for poorly bunched beams. This stems from particles occupying outer synchrotron oscillation orbits in the LBET, causing unwanted bunch-bunch interactions and degraded beam quality. To address this, we proposed using temporally spaced laser pulses to selectively photo-detach electrons from the longitudinal head and tail regions of H- ion bunches. This approach aims to reduce particle density in extreme orbits, enhancing beam uniformity and limiting emittance growth. Our experiments employed Fermilab's 'LaserNotcher' system at the font end of the linac, delivering 1.6 MW peak power with sub-nanosecond precision. By neutralizing the first and last half-nanosecond of several H- bunches, we measured their propagation injection into the booster. Measurements of pulse width, average height, and temporal spacing over booster cycles were compared between the scraped and unscraped bunches. Statistical analysis evaluated the results’ significance, highlighting the feasibility of laser-based scraping for future linac designs to achieve higher beam energies with improved emittance control.

Speaker: Parker Landon (Boston University)

16:00 Extracting symplectic maps for space-charge dominated beams

Symplecticity of the transfer maps is important for reliable evaluation of space-charge dominated beams in accelerators. Unfortunately, most simulation codes that include collective effects, such as space charge, do not use canonical phase-space variables and therefore are not symplectic in the presence of electromagnetic fields. In this paper, we present a numerical method to extract symplectic transfer maps using particle tracking simulation code IMPACT-T for space-charge dominated beams. We demonstrate this method by obtaining symplectic transfer maps in the photo-injector (113 MHz SRF gun) section of the Coherent electron Cooling (CeC) Proof of Principle (POP) experiment.

Speaker: Nikhil Bachhawat (Stony Brook University)

16:00 Fast and efficient modeling of structure-based wakefield accelerators

Structure-based wakefield accelerators (SWFA) have been identified as a candidate technology for future applications ranging from free electron lasers to colliders. However, achieving the desired beam energy and quality requires meter-scale structures with tight tolerances, placing constraints on structure and beam characteristics to minimize emittance growth and combat transverse instabilities. High fidelity and self-consistent simulations over these lengths necessitate enormous computational resources, making parametric studies of novel structures or instability-mitigation schemes unfeasible with standard practices. We present a technique for decomposing high dimensional wakefield systems into a set of lower dimensional components, capable of accurately reconstructing the structure response in a fraction of the time. We discuss the approach and implementation of this technique using Green’s Functions for common structure geometries. We demonstrate the potential for significant reduction in computation times and memory footprint using such representations. Finally, we discuss the application of machine learning in generating these representations for novel structure geometries.

Speaker: Nathan Cook (RadiaSoft (United States))

16:00 Filling pattern with non-uniform bunch spacing to mitigate e-cloud for the FCC-ee

The Future Circular Collider (FCC) study is developing designs for higher performance particle colliders that could follow on from the Large Hadron Collider once it reaches the end of its high-luminosity phase. In particular, the FCC-ee is a proposed electron-positron collider that may face challenges from the electron cloud (e-cloud). Specifically, the Z configuration foresees the highest number of bunches. Consequently, this configuration could suffer more form the deleterious effects of the e-cloud, such as transverse instabilities, transverse emittance growth, particle losses, vacuum degradation and additional heat loads on the inner surface of the vacuum chambers. The e-cloud effects have been observed in several circular accelerators all over the world and it is much more commonly in those operated with positively charged particles. Presently, it is among the major performance limitations for high energy collider. Therefore, the study of e-cloud mitigation techniques is crucial during the accelerator's design stage to suppress the e-cloud avalanche multiplication. This paper analyses the use of non-uniform bunch spacing patterns as a potential e-cloud mitigation strategy.

Speaker: Dr Luca Sabato (École Polytechnique Fédérale de Lausanne)

16:00 First proton crabbing at the LHC via head-on beam-beam interaction

The first experimental observation of a 10 $\mu$m crabbing orbit at 1~$\sigma_z$ induced by head-on collisions with a non-zero crossing angle ($\theta_c$) in a high-energy proton beam at the LHC is presented. This challenging measurement required both the design of a dedicated experiment and a careful calibration and optimization of the beam instrumentation to produce and detect such a subtle effect. By varying the crossing angle from positive to negative values the reversibility of the effect and its dependence on the crossing angle were also demonstrated. Lattice simulations were performed to corroborate the experimental results, showing excellent agreement with the measured crabbing amplitudes. This experiment highlights the potential of the existing wideband beam-position monitors to diagnose crabbing effects, which will be crucial in the HL-LHC upgrade.

Speaker: Andrea Fornara (University of Manchester)

16:00 Full simulation model of crystal-based extraction from an accelerator using BDSim and Geant4 G4ChannelingFastSimModel

Oriented bent crystal planes can deflect charged particles as strongly as a magnetic field exceeding 100 T. As a result, beam extraction from an accelerator using oriented crystals offers significant opportunities for diverse applications, ranging from beam tests for particle detector R&D to high-energy fixed-target experiments. However, designing these applications requires a universal simulation tool that accurately describes the physics of crystals, beam dynamics in an accelerator, and particle interactions with materials.
We present a new simulation model realized using the BDSIM * , built on the Geant4 toolkit ** , to simulate particle transport in accelerators and their interactions with materials. The model includes a bent crystal as a new BDSIM accelerator component, leveraging the latest Geant4 features, G4ChannelingFastSimModel *** and G4BaierKatkov, to incorporate channeling physics and radiation losses, respectively.
This model was applied to simulate the crystal-based extraction of 6 GeV electrons from the DESY II Booster Synchrotron ****. We present the calculated parameters of the extracted beam and discuss the feasibility of a proof-of-principle experiment.

Speaker: Edgar Cristopher Cortés García (European Organization for Nuclear Research)

16:00 GPU accelerated longitudinal phase space tomography

Longitudinal tomography is widely used in the CERN synchrotrons as an essential beam diagnostics tool. In recent years, more complex applications of phase space tomography, such as voltage calibration and multi-bunch tomography, have been explored. For these applications, large numbers of reconstructions are required, and computation time has a significant impact on usability. The current implementation is Python based, with the numerically intensive components written in C++. To further increase performance, a GPU-accelerated version has been developed using CuPy and CUDA. The most computationally demanding parts of the algorithm can now be run on the GPU, whilst maintaining the Python interface for maximum flexibility. Performance benchmarks showed speedups up to a factor of 35 in the scope of the entire application and even higher values when only considering the computationally intensive parts. This contribution discusses the implementation of GPU tomography as well as the additional performance improvements it enables.

Speaker: Simon Albright (European Organization for Nuclear Research)

16:00 GPU-Accelerated Study of Longitudinal Single-Bunch Instability in Electron Storage Rings

Longitudinal single-bunch instability caused by high-frequency impedance poses a major challenge for achieving optimal performance in fourth-generation synchrotron light sources and future electron-positron colliders. Accurate simulations of this instability are critical but computationally intensive, requiring millions of macro-particles and dense slicing to resolve bunch density distributions. To address this, we present a GPU-accelerated tracking code that enables efficient longitudinal single-bunch instability simulations. Designed for high-performance GPUs on desktop computers, our approach provides an accessible, cost-effective alternative to computing clusters.

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

16:00 High efficiency L-band IOT design and high power testing

Recent efforts at SLAC aim at developing high-power accelerators powered by compact, high-efficiency rf sources such as klystrons and Inductive output tubes (IOT). In particular, a high-efficiency IOT is an electron-beam-driven RF source employed in the UHF band that offers high efficiency at variable output power levels. In this talk, we show the progress of developing a 1.3 GHz HEIOT in terms of design, and manufacturing.

Speaker: Mohamed Othman (SLAC National Accelerator Laboratory)

16:00 High power testing of 500MHz room temperature high-frequency cavity

The high-frequency cavity system of the Wuhan Advanced Light Source (WALS) utilizes a normal temperature single-cell cavity with heavily damped higher-order modes. The operating frequency of this cavity is 499.654 MHz. Power from a solid-state power source module passes through a circulator and then is fed into the main cavity via a waveguide. The coupler is designed to be compatible with both circular waveguides and coaxial waveguides, and the coupling coefficient can be continuously adjusted within the range of 1 to 3. This paper reports that in November 2024, the 500 MHz normal temperature high-frequency cavity of WALS has successfully completed a 50 kW high-power test, effectively validating the performance of the high-frequency cavity and the stability of the high-frequency system.

Speaker: Jianhao Tan (Shanghai Advanced Research Institute)

16:00 Impedance estimation and instability analysis for Korea-4GSR storage ring

Korea-4GSR is a future light source in Korea with a circumference of 800 m, an energy of 4 GeV, and a maximum current of 400 mA. Due to the small aperture of the vacuum chamber (12H x 9V octagonal) and the large number of normal-conducting cavities and beam position monitors (BPMs), impedance-induced instabilities are expected to pose challenges at 400 mA operation. In this study, we estimated the storage ring impedance of Korea-4GSR and investigated both single-bunch and multi-bunch instabilities to determine optimal operational conditions, including the analysis of fill patterns

Speaker: Jimin Seok (Pohang Accelerator Laboratory)

16:00 Impedance reduction of the beam wire scanners for the CERN LHC

The beam wire scanners are instruments for precise transverse beam profile measurements by detecting the secondary particles generated from the interaction of the beam with a moving carbon wire. Following a completely new design of this device for the Large Hadron Collider (LHC), a detailed impedance calculation has been performed already in the design phase. This contribution presents the beam coupling impedance optimization and reduction strategy of the beam wire scanners for the High-Luminosity (HL) upgrade of the LHC. Prior to the construction of the prototype, extensive three-dimensional electromagnetic simulations of the proposed mechanical designs were performed to detect potential resonances and their sources. The mechanical model was improved to minimize the beam coupling impedance by geometrical modifications and coatings. We also present the beam-induced RF power loss calculation of the instrument.

Speaker: Jake Flowerdew (European Organization for Nuclear Research)

16:00 In-situ XPS study of low-temperature baking of SRF niobium cavities

We investigated the effects of low-temperature baking, a standard treatment for superconducting radiofrequency (SRF) cavities, on niobium samples using synchrotron X-ray photoelectron spectroscopy. The study examined the chemical state of the niobium surface after chemical treatment with a buffered etching solution, which leaves a native oxide layer, fluorine impurities, and surface hydrocarbons. In-situ analysis was conducted during baking at 120°C for 48 hours in ultra-high vacuum. No significant changes in the core levels were observed; however, subtle variations were detected in the Nb 3d and C 1s spectra. Specifically, the most intense C 1s peak shifted to lower binding energies, indicating the formation of new chemical bonds. Additionally, partial transformation of Nb⁵⁺ to Nb⁴⁺ was observed, with no detectable oxygen depletion within the depth probed by XPS. The potential influence of X-ray exposure on the chemical state of these elements is also discussed.

Speaker: Alena Prudnikava (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 INFN LASA in-kind contribution to PIP-II

This paper reports the status and recent progress of INFN LASA’s in-kind contribution to the PIP-II project at Fermilab, with updates on key activities and major procurements. Production efforts for the 38 INFN LASA-designed, 5-cell cavities (β=0.61) for the LB650 section of the linac are underway and two pre-series prototypes are being realized as a first step to validate the manufacturing and treatment sequence. Concurrently, preliminary testing on existing prototypes is progressing to gain a deeper understanding of the surface preparation and qualification procedures, including cross-validation at different infrastructures. Series LB650 cavities will be industrially produced and surface-treated to achieve the stringent performance targets, qualified via vertical cold tests at DESY AMTF, and delivered installation-ready for string assembly.

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

16:00 Interaction of intrabeam scattering, longitudinal wakefield, and a passive harmonic RF cavity in SOLEIL II

Synchrotron light sources worldwide are transforming into next-generation facilities with ultralow transverse emittances at the diffraction limits. With these parameters, intrabeam scattering (IBS) becomes significant and can spoil the light quality by increasing emittance. A harmonic cavity can be installed to mitigate this effect by increasing the bunch length. Another way to reduce the impact of IBS is to operate with the full transverse coupling. This contribution considers the IBS effect on SOLEIL II performance with an up-to-date impedance model, passive harmonic cavity, different insertion device gap configurations (open, close), and full transverse coupling for all foreseen operation modes. The combined effect of IBS and microwave instability (MWI) on the energy spread is reported. It is demonstrated that the contribution of IBS to energy spread increase is as important as that of MWI.

Speaker: Sami Habet (Synchrotron soleil)

16:00 Intrabeam scattering in SRF "SKIF" storage ring

SKIF (Russian acronym for Siberian Circular Photon Source) – is a new fourth generation synchrotron light source under construction in Novosibirsk, Russian Federation.
One of the most important characteristics of the synchrotron radiation source SRF "SKIF", which in turn determines its brightness, is the ultra-low emittance of the electron beam, which depends on the operating regime and parameters of the storage ring: the intensity of the electron beam, the insertion devices parameters, the coupling coefficient of linear betatron oscillations, the elongation of the bunches, etc. Intrabeam scattering (IBS) is a collective effect that causes bunch volume inflation and brightness decrease for high intensity beams.
Described in this work are the results of study of IBS impact on beam emittance, energy spread, Touschek lifetime and geometrical brightness for different operating regimes of the SRF “SKIF” storage ring.

Speaker: Mr Mikhail Skamarokha (Budker Institute of Nuclear Physics, Synchrotron Radiation Facility — Siberian Circular Photon Source «SKIF» Boreskov Institute of Catalysis)

16:00 Investigating electron cloud formation in FCC-ee nested magnet designs

The Future Circular Collider is an ambitious international proposal for a next-generation particle accelerator complex, building upon the successes of CERN’s Large Hadron Collider. Specifically, the FCC-ee is a future circular lepton collider. The baseline design for the FCC-ee features four modes of operation, with beam energies ranging from 45.6 GeV to 182.5 GeV. Electron cloud (e-cloud) could be a concern for the FCC-ee due to the high number of bunches foreseen for the Z configuration, which results in small bunch spacing. The bunch spacing is a key parameter for the e-cloud formation process, as very small bunch spacing could lead to the avalanche multiplication and its deleterious effects. Moreover, electron trajectories are strongly influenced by externally applied magnetic fields, which could trap electrons and alter their survival time inside the vacuum chamber. The concept of nested magnets, which involves overlapping dipole fields with quadrupolar and/or sextupolar gradients, is under investigation. This approach aims to increase the dipole filling factor and reduce the synchrotron radiation. In this paper, the nested magnets are studied from the e-cloud point of view.

Speaker: Dr Luca Sabato (École Polytechnique Fédérale de Lausanne)

16:00 Investigating the Impact of alternative LHC optics on accelerator backgrounds at FASER using BDSIM

Alternative configurations around the ATLAS experiment are investigated aiming to reduce muon rates at forward physics experiments such as FASER and SND@LHC. The Geant4 toolkit BDSIM is used to propagate muons through a model of a section of the LHC and the TI12 tunnel, where the FASER experiment is located. We compare the muon rates in BDSIM with FASER data collected during dedicated tests in the LHC. Results show a significant worsening of the background with the non-nominal polarity configuration of the triplet quadrupoles, used in 2024. The horizontal crossing angle further increased the background, however a partial mitigation of approximately 10% was found using a set of orbit corrector magnets. Additionally, nominal triplet polarity was favorable for both vertical and horizontal crossing angles. This work served as benchmark of simulations that will be used to validate future configurations.

Speaker: Alex Keyken (Royal Holloway University of London)

16:00 Ion effects on the space charge limited emission for particle-in-cell simulations

Space charge limited (SCL) emission is of fundamental importance to vacuum electronic devices, where the self-field of emitted charges limits the maximum current density being emitted from a cathode surface. Traditional modeling of SCL emission using the Child-Langmuir law primarily focuses on electron dynamics, neglecting the role of ions, which can significantly influence emission dynamics. In this work, we extend a previously developed simple SCL algorithm for implementing the Child-Langmuir law at the surface grid in particle-in-cell (PIC) simulations to study ion effects. The presence of ions introduces new dynamics, affecting the steady-state current, the evolution of surface electric fields, and the transient behavior of SCL emission. Using the 1-D electrostatic PIC code, XPDP1, developed by the Plasma Theory and Simulation Group (PTSG), we investigate these ion-induced modifications and test the influence of ions on the SCL emission algorithm. The extended algorithm ensures an accurate computation of the surface electric field via Gauss’s law to resolve the space charge contribution from both ion motion and electron emission, and the findings will be discussed in detail.

Speaker: Kaviya Aranganadin (Hanyang University)

16:00 Longitudinal beam coupling impedance of unshielded pumping manifolds at the CERN PS

The High-Luminosity LHC (HL-LHC) project aims at increasing beam intensity, hence posing tight constraints on its injector chain. A critical issue in the Proton Synchrotron (PS) is the contribution of numerous pumping manifolds to the longitudinal beam coupling impedance at high frequencies. It causes microwave instabilities that particularly affect ion beams and limit the longitudinal density of proton bunches close to transition energy. This contribution characterizes the impedance of these vacuum components through detailed electromagnetic simulations, examining configurations with and without a pick-up head inserted in the manifold. The effect of damping resistors on the impedance behavior is also investigated. Mitigation strategies, including shielding to prevent beam coupling with the manifold's volume, are evaluated for their effectiveness using electromagnetic simulations, offering solutions for improved beam performance.

Speaker: Jake Flowerdew (European Organization for Nuclear Research)

16:00 Longitudinal microwave instability in the J-PARC Main Ring

Longitudinal microwave instability has been observed in the J-PARC Main Ring. The longitudinal microwave instability was observed during the debunching process for the slow extraction. This led to electron cloud formation, which can cause transverse beam instability and beam losses. Longitudinal microwave instability was also observed during the latter part of the acceleration for the fast extraction operation, even though no loss or transverse instability related to the longitudinal microwave instability was observed. To investigate the source of the longitudinal microwave instability, spectral analysis was used on the waveform recorded by a high-speed oscilloscope. The spectral analysis suggests the RF cavity and its structure as a possible source of the longitudinal microwave instability. A beam longitudinal dynamics simulation with measured longitudinal impedance of the RF cavity was performed, and its result is compared with the measurement for various beam intensities. In this paper, we present the result of the simulation and measurement of the longitudinal microwave instabilities for various beam intensities.

Speaker: Yasuyuki Sugiyama (High Energy Accelerator Research Organization)

16:00 Machine learning-based symplectic model for space-charge effect simulation

Symplectic simulation of space-charge effects is important for high-intensity particle accelerators. In this work, we propose to use a generative model to efficiently simulate space-charge effects in JuTrack, a Julia-based particle tracking code. The one-step symplectic transverse transfer map of the particles is obtained by differentiating the predicted space-charge Hamiltonian. This model effectively preserves the phase-space structure and reduces non-physical effects in long-term simulations by ensuring symplecticity in the calculation.

Speaker: Jinyu Wan (Facility for Rare Isotope Beams)

16:00 Magnetic properties of niobium processed with high- and low-temperature nitrogen baking for SRF applications

We systematically investigated the effects of various thermal treatments on the superconducting properties of niobium. In this study, niobium is utilized for fabricating nine-cell 1.3 GHz cavities used in particle accelerator facilities. Cylindrical niobium samples underwent the same chemical and thermal treatments applied to superconducting radiofrequency (SRF) cavities, including buffered chemical polishing (BCP), low-temperature baking (LTB), N-doping, and N-infusion. Magnetization curves and complex magnetic susceptibility were measured across a broad temperature range (2–9 K) and in dc magnetic fields up to 1 T. Bulk superconductivity parameters such as the critical temperature (Tc), thermodynamic critical field (Bc), and upper critical field (Bc2) were determined for samples subjected to different treatments. Notably, the Bc2 field exhibited significant variation depending on the treatment, reaching its highest value for N-doped niobium. Additionally, evidence of surface superconductivity at fields exceeding Bc2 was observed in all thermally treated samples, with the critical surface field surpassing the Ginzburg-Landau field in all cases.

Speaker: Alena Prudnikava (Helmholtz-Zentrum Berlin für Materialien und Energie)

16:00 Measurement of coherent synchrotron frequencies under conditions close to the Robinson limit at the Aichi Synchrotron Radiation Center

Past measurements* of coherent synchrotron frequencies at the Photon Factory storage ring revealed that the behavior of measured coherent frequencies could not be well explained with standard 4th-order characteristic equation under conditions close to the Robinson limit. To investigate whether similar phenomenon occurs in other storage rings, we measured the coherent synchrotron frequencies at a 1.2-GeV electron storage ring of Aichi Synchrotron Radiation Center as a function of the cavity voltage and the beam current. At beam currents higher than about 200 mA, we observed double peaks, one with a frequency higher than the incoherent synchrotron frequency and one with a lower frequency, that can correspond to two independent solutions of the 4th-order characteristic equation. Our preliminary analysis indicated that the frequencies of lower-frequency peak did not agree well with those predicted by the characteristic equation. We also observed that under a condition very close to the Robinson limit, the beam exhibited strong longitudinal coherent self-excited oscillation without beam dump. We present these measurement results and updated analysis.

Speaker: Shogo Sakanaka (High Energy Accelerator Research Organization)

16:00 Microbunching gain evaluation of bunch compressor designs

Many accelerators have to take microbunching gain into consideration during both design and operation; this typically involves beam parameters where space charge is negligible. However, there are some accelerator designs which involve bunch compression of low energy beams with very low slice energy spread - conditions which may be prone to both microbunching considerations as well as space charge. In this paper, we examine the impacts of space charge on the microbunching gain of bunch compressor chicanes of various designs.

Speaker: Kirsten Deitrick (Thomas Jefferson National Accelerator Facility)

16:00 Microwave instability driven by terahertz-scale resistive-wall impedance in Diamond-II

Vacuum vessels of the Diamond-II storage ring feature non-evaporable getter (NEG) coating which cause a resonator-like peak in the longitudinal impedance. This work demonstrates how different parameters of NEG can increase momentum-spread growth. It is shown that the spread of the coating-layer thickness amongst vacuum vessels results in significantly reduced momentum-spread growth. Insertion devices featuring rectangular geometry and NEG coating can cause a multi-peak structure of the longitudinal impedance which can drive additional momentum-spread growth.

Speaker: Ian Martin (Diamond Light Source)

16:00 Multi-objective optimization of ring cyclotron RF cavity using neural network ensembles with uncertainty quantification

This study presents a multi-objective optimization scheme for ring cyclotron RF cavities, leveraging a neural network ensemble surrogate model. The cavity geometry is parameterized using Non-Uniform Rational B-Splines (NURBS), with control points and weights as design parameters. To reduce the computational cost of direct eigenmode simulations, an ensemble of neural networks trained using Ansys HFSS results is used to approximate performance metrics efficiently. The surrogate model also quantifies uncertainty, enabling Monte Carlo error propagation to account for potential manufacturing deviations. A multi-objective genetic algorithm (MOGA) explores the design space, using the surrogate model for efficient evaluations. The neural network ensemble are periodically retrained through HFSS simulations, iteratively improving the accuracy of surrogate model. This approach gives a robust and reliable RF cavity design optimization scheme.

Speaker: Ahsani Hafizhu Shali (Osaka University)

16:00 Ongoing vertical testing and high-pressure rinsing simulations of single-spoke resonator cavities

Vertical tests of single-spoke resonator type 1 (SSR1) superconducting cavities were conducted in conjunction with high-pressure rinsing (HPR) simulations to assess and improve cavity performance. The quality factor (Q) was evaluated as a function of the accelerating field (Eacc), Lorentz force detuning (LFD), and pressure sensitivity. In the HPR simulations, water droplet dynamics emitted from a 0.5 mm diameter nozzle operating at 100 bar were analyzed as a function of travel distance. The simulations provided detailed estimates of the velocity and impact force of the water jet, which are critical for optimizing cavity surface cleaning.

Speaker: Heetae Kim (Institute for Basic Science)

16:00 Performance of HOM dampers in the 100 MHz RF cavities in the MAX IV 3 GeV ring

Throughout 2023 and 2024, higher-order mode (HOM) dampers were designed, manufactured and installed on the 100 MHz RF cavities in the 3 GeV ring at MAX IV Laboratory. Cavity HOMs have been the main driving source of longitudinal coupled-bunch modes (LCBM) in the ring. This contribution presents the impact of the HOM dampers via measurements performed on the cavities at different operating temperatures. Measurements were made of the transmission between two probe antennas, the fields excited in the cavities by a single bunch stored in the ring and the damping rates of the LCBMs extracted using the drive-damp technique with a multibunch stored beam.

Speaker: Henrique Duarte (MAX IV Laboratory)

16:00 Performance of the diode stack with resistors to suppress beam instability at the J-PARC RCS

The main source of beam instability in the J-PARC 3-GeV RCS is the impedance of the eight installed kickers. This arises because one end of each kicker magnet is shorted while the other end is left open during beam acceleration. The shorted-end configuration provides the benefit of power savings during beam extraction from the RCS. However, it also excites beam instability. To retain the energy-saving benefit while suppressing beam instability, we developed a diode stack with resistors and inserted it at the open ends of four kickers. This configuration effectively suppresses beam instability for smaller-emittance beams, which are delivered to the MR at J-PARC.

Speaker: Kota Okabe (Japan Proton Accelerator Research Complex)

16:00 Photoinjector beam halo formation due to a secondary picosecond time-delayed laser pulse

Beam halo formation is a significant challenge for high-intensity accelerators, as it can lead to performance degradation and radiation safety risks. This study investigates the formation and mitigation of beam halos caused by a picosecond time-delayed laser pulse, which generates a secondary electron bunch in the same RF bucket as the main bunch. The energy difference between the two bunches creates a defocusing effect, leading to the halo generation. Experimental validation of RF-Track simulations was conducted at the AWAKE Run 2c test injector (ARTI). The research outlines methods for identifying, analyzing, and mitigating laser-driven beam halo formation, contributing to more effective control of beam halos in accelerator operations.

Speaker: Vlad Musat (European Organization for Nuclear Research)

16:00 Plasma processing of ESS elliptical cavities

Plasma treatment has proven effective in recovering and reducing field emission in the affected superconducting radiofrequency (SRF) cavities. A joint effort is underway between CEA, ESS and INFN to apply this technique to the treatment of elliptical cavities in the ESS linac. This paper presents the work done so far, which aims at both the development of the plasma process for cavities in the cryomodule and the treatment of cavities in the vertical test configuration. The peculiarity of ESS cavities compared with typical cavities at 1.3 GHz is the absence of couplers for higher orders.

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

16:00 Predicting losses in the SPS using longitudinal tomography during bunch shortening in the PS

The efficient transfer of protons from the Proton Synchrotron (PS) to the Super Proton Synchrotron (SPS) is crucial for beams in the Large Hadron Collider (LHC). A particular challenge at the intensities required for the High-Luminosity LHC is the handover from a 40 MHz to a 200 MHz RF system. This requires a non-adiabatic bunch shortening in the PS triggered by a fast RF voltage jump. However, nonlinearity of the synchrotron frequency distribution causes tails to emerge during rotation, resulting in uncaptured beam in the SPS. The uncaptured particles lost at the start of acceleration in the SPS, and the additional flat bottom losses, can currently only be evaluated with the beam intensity and loss monitors. In this work, detailed studies of the bunch rotation in the PS were carried out both in simulations and in measurements. A tomography-based tool was developed to predict uncaptured losses in the SPS from bunch profile measurements in the PS during bunch shortening. This tool enables detailed monitoring of the PS-to-SPS transfer of LHC-type beams by identifying potential losses due to uncaptured beam, before injection into the SPS.

Speaker: Jake Flowerdew (European Organization for Nuclear Research)

16:00 Preliminary results on the electron cloud build-up in the booster of the FCC-ee

The presence of the electron cloud inside the chamber of high energy accelerators with positively charged circulating beams has been reported and studied by several facilities. Those studies intend to describe and predict which scenarios may present a mayor risk to operating the machine.
The electron cloud build-up inside the vacuum chambers might generate critical effects that diminish the performance of the machine and beam quality. Due to these reasons, it is important to review the possible scenarios to operate at injection and extraction of the beam inside the booster proposed for the FCC-ee. This work reports preliminary studies on electron cloud evolution inside the booster, considering some variations in strategic design parameters, such as the bunch spacing, and secondary emission yield. We compare the simulated electron distribution across the two stages of the beam.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

16:00 Preliminary study of higher-order mode based scheme for bunch length compression in SRF Electron guns

Higher-Order Modes (HOMs) in superconducting radiofrequency (SRF) cavities are traditionally considered detrimental to efficient operation. They are often associated with beam instabilities and are actively damped. However, these “harmful” HOMs, if used strategically, can be transformed into a tool for providing extra control over the beam, which can introduce new opportunities that are not easily achievable by conventional SRF cavity-based systems. Particularly, we have investigated the feasibility of boosting ballistic bunch compression using HOMs in SRF gun.  The proposed idea will be presented with preliminary simulation results. The 185 MHz SRF gun cavity used for the simulation study was modelled using the ACE3P software suite and further modelling of the compression scheme was performed using the GPT code.

16:00 Progress & developments of beam delivery simulation (BDSIM)

BDSIM (Beam Delivery Simulation) is a Monte Carlo particle tracking tool for accelerator beamline modelling. It integrates particle transport with detailed geometry and physics using Geant4 for precise modelling of particle-matter interactions in 3D models of particle accelerators. Primarily for energy deposition studies and beam loss simulations, BDSIM allows a high degree of control and customisation, and is ideal for understanding and enhancing the performance of beamline designs. BDSIM has numerous modelling applications, including high-energy physics facilities, particle detection experiments, synchrotron light sources, medical accelerators, and novel acceleration experiments.
Here, we present recent developments of BDSIM. This includes improved custom inverse-Compton scattering processes for laserwire and polarimeter simulations and extending the process to model polarization & electron spin; improved acceleration including transverse focussing in RF elements with implementation of 3D transverse magnetic and electric modes; custom elements for modelling muon cooling channels; and updates to interfacing with Xsuite via improved code couplings and BDSIM distribution methods.

Speaker: Stewart Boogert (Cockcroft Institute)

16:00 Progress on experimental efforts to investigate CSR shielding effects

A collaboration is underway to investigate the impact of CSR and shielding on the beam of various shapes as it passes through a chicane. Experimental efforts are being made at the Argonne Wakefield Accelerator (AWA) facility. Currently, the facility is equipped with two identical doglegs with reversing quadrupoles that allow doglegs to function as a chicane, and manually adjustable shielding gaps in dipole magnet chambers. A 6.4-ps-long flattop laser pulse is generated using alpha-BBO crystals, and linac phase is adjusted to either preserve the bunch length or slightly compress it through the chicane. While the expected beam behavior was observed during the initial experiment, the current chicane’s exceptionally large R56 (=0.45 m) rendered it sensitive to modulations from the alpha-BBO configuration. We have confirmed a new beam-based tuning procedure for BBO crystals at the AWA facility and its effect on modulations. We present the summary of experimental efforts to date and outline future plans.

Speaker: Alex DeSimone (Northern Illinois University)

16:00 Python FLUKA beam line, a python library to create FLUKA simulations of accelerators

FLUKA simulations of beamlines are important for un- derstanding numerous different aspects of accelerators, in- cluding beam losses, particle backgrounds, activation and shielding. Creating a beam-line simulation using FLUKA is a time consuming and potentially error prone process. This paper describes a set of python tools called pyflubl (Python FLUKA beam-line) which can create a FLUKA simulation using input from MAD-X, MAD8, Transport or BDSIM. pyflubl is based on multiple stable and advanced python packages created to make BDSIM (Geant4) beamline simu- lations as simple as possible, these are pymadx (an interface to MAD-X output), pymad8 (an interface to MAD8 out- put), pybdsim (interface to BDSIM) and most importantly pyg4ometry (a geometry engine for Monte Carlo geometry creation). The magnetic fields required for FLUKA are im- plemented in C++ via BDSIM, thus keeping fields consistent between Geant4 and FLUKA beamline simulations. This paper describes pyflubl design and implementation and ex- ample results for an idealised electron beam-line. Particular attention is given to geometry, fields and scoring.

Speaker: Stewart Boogert (Cockcroft Institute)

16:00 Quadrupole pumping for bunch shortening in the Proton Synchrotron and Super Proton Synchrotron at CERN

Quadrupole pumping is a longitudinal manipulation technique for bunch shortening, which works by modulating the RF voltage at twice the synchrotron frequency to excite bunch length oscillations. These controlled oscillations rotate the bunch in longitudinal phase space, with extraction set for when the bunch is shortest. Higher RF harmonics can also be used to linearise the synchrotron frequency distribution, reducing the formation of tails. Recently, quadrupole pumping has been proposed as a method for achieving ultra short bunches for proton-driven plasma wakefield accelerators such as the AWAKE experiment. In this contribution, we assess the performance of quadrupole pumping for the first time in the Proton Synchrotron (PS) and Super Proton Synchrotron (SPS) at CERN. Using simulations and beam measurements, we compare the effectiveness of this technique (without linearisation) against other bunch-shortening methods, including the unstable phase jump and the non-adiabatic voltage jump.

Speaker: Jake Flowerdew (European Organization for Nuclear Research)

16:00 R&D on SRF cavities at INFN-LASA

As part of its ongoing and future contributions to high-Q/high-G activities in major international projects such as PIP-II, ILC Technology Network, and the European Strategy for Particle Physics, INFN-LASA is upgrading its experimental facility for vertical cold tests of superconducting cavities. This upgrade will enable cavity performance characterization in a low residual magnetic field environment and with dedicated diagnostics for understanding possible performance limitation. In parallel, state-of-the-art surface treatments aimed at achieving high-Q and high-G performance are being developed and applied to single and multicell cavities at different frequencies. This paper presents the current status of the facility, its key features, an overview of cavities currently in production, and the experimental results obtained to date.

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

16:00 Reconstructing wake functions using Haissinski distributions from multiple bunch charges

Accurate knowledge of wake functions is crucial in accelerator physics, serving as the cornerstone for understanding intra-bunch interactions and for controlling or mitigating instabilities that limit accelerator performance. Haissinski distributions, which describe the steady-state longitudinal bunch density, are intrinsically determined by the wake function experienced by the bunch. While these distributions are typically computed from a given wake function, we investigate the inverse problem: extracting the wake function directly from measured Haissinski distributions.
In this theoretical work, we introduce a novel method to reconstruct wake functions by utilizing Haissinski distributions obtained at multiple bunch charges. By combining these profiles into an overdetermined system, we address challenges posed by the inverse problem, which is sensitive to noise and discretization errors. Here, our preliminary results suggest that the use of regularization techniques may help achieve more stable reconstructions of the wake function.

Speaker: Felipe Donoso (Karlsruhe Institute of Technology)

16:00 Report on Opera-3D hands-on session in the 7th International School on Beam Dynamics and Accelerator Technology (ISBA24)

The 7th International School on Beam Dynamics and Accelerator Technology (ISBA24) held in Chiangmai University during November 1-9, 2024, encompasses seven days opportunities where the foundation of accelerator physics is applied during hands-on sessions with simulation software including ASTRA, ELEGANT, Opera-3D and CST Studio Suite. Opera-3D, a finite element-based Maxwell’s equations solver, is known for its powerful low frequency simulation capabilities and is appropriate for magnet design. Instructed by two lecturers from Synchrotron Light Research Institute, 15 students from China, Japan, India and Thailand were trained on the Opera-3D software fundamentals in the application of magnet design for particle accelerator. The students showcase their knowledge in the group assignments including the design of H-shape dipole, C-shape dipole and combined horizontal and vertical corrector with success. Thanks to the generous support of the ISBA24 sponsors and Sigma Solutions Co., Ltd., who provided the software licenses during the school. This article reports on the completion of the ISBA24 Opera-3D hands-on session provided to graduate students and young researchers from the Asian region.

Speaker: Prapaiwan Sunwong (Synchrotron Light Research Institute)

16:00 Report on the hands-on training with the ELEGANT code at ISBA24

The 7th International School on Beam dynamics and Accelerator technology (ISBA24) took place over nine days, from November 1 to 9, 2024 at Chiang Mai University in Thailand. The school, part of the KEK-IINAS-NX series, was jointly hosted by Chiang Mai University and the Synchrotron Light Research Institute (SLRI). Out of 115 applicants who had submitted resumes and recommendation letters, 64 students from nine countries (Thailand, China, Japan, Indonesia, Korea, Taiwan, India, Germany, and Turkey) were selected to participate the school. During the ISBA24 school period, we opened four hands-on trainings with ASTRA, ELEGANT, CST, and OPERA codes to deepen students’ understanding of accelerator theory and improve their skills in accelerator design. All students chose one of the hands-on trainings according to their interests. In the ELEGANT hands-on training, approximately 20 students learned to use the ELEGANT code to design the various 4th generation synchrotron light sources with the Multi-Bend Achromat (MBA) magnet lattices. In this paper, we report details on the ELEGANT hands-on training conducted during ISBA24.

Speaker: Yujong Kim (Korea Atomic Energy Research Institute)

16:00 RF design of an integrated X-band mode-launcher for an open-structure TW LINAC

In this paper, we present the RF design of a mode-launcher integrated with an open-type, multi-cell 12 GHz 4-sector structure. The electromagnetic design is carried out using the 3D full-wave electromagnetic solver CST-Microwave Studio. To ensure compactness, a key focus of the integration process is the minimization of the distance between the coupler cell and the accelerating open structure. We evaluate the feasibility of two solutions: two conventional couplers, and another configuration with two mode-launchers employed at both the input and output ends of the accelerating structure. A comparison is performed to assess the performance of the proposed design

Speaker: Giuseppe Torrisi (Istituto Nazionale di Fisica Nucleare)

16:00 RF window ghost mode analysis

The RF window acts as a barrier between the vacuum and air, gas, or water while allowing RF power to pass through with minimal loss. Resonant modes (called "ghost modes") can occur within the ceramic disk of a window. The frequencies of these modes depend on the material and size of the ceramic. Ceramic disk dimensions must be carefully optimized to minimize reflections and avoid ghost mode resonances within the operating bandwidth. In this paper we present the design of an input window used in an X-band klystron. The dimensions of the window and ceramic disk are optimized to minimize insertion and reflection losses while preventing ghost mode resonances in the operating bandwidth. In addition to this, we ensure that the maximum electric field at the window surface is kept low to reduce the probability of RF breakdowns. Analytical analysis, numerical simulations and experimental measurements of the ghost modes of ceramic disks were carried out. The measured ghost mode frequency was used to evaluate the ceramic dielectric constant. In this article we present simulated and measured results.

Speaker: Ankur Dhar (SLAC National Accelerator Laboratory)

16:00 Simulation of electron beam transport through the coherent electron cooling amplification section using real number of electrons

Coherent electron cooling plays an important role in the Electron Ion Collider (EIC) by providing a fast cooling rate at collision energy to counter the emittance growth driven by intrabeam scattering effects. In this paper, we report on the high-fidelity simulation of the electron beam transport through the amplification section of the cooling channel. We will show the amplification of the initial modulation in the electron beam from the protons and present the study of collective effects such as the space-charge and CSR effects on the process of modulation amplification.

Speaker: Ji Qiang (Lawrence Berkeley National Laboratory)

16:00 Simulation of three-dimensional magnetic confinement of a Coulomb crystal in a ring

A novel storage ring is proposed in which the bunch maintains a fixed orientation relative to the outside world (does not rotate with the ring as usual). In this geometry, magnetic focussing can confine all three dimensions of the bunch without RF. The application of this ring to ultra-low emittance Coulomb crystals is investigated, where the focussing force balances the space charge to give zero phase advance and the crystal structure can be preserved for tens of milliseconds. The dynamics is highly coupled and dominated by weak focussing. Some different instabilities are observed, one of which appears to be suppressed by adding nonlinear components to the ring field.

Speaker: Stephen Brooks (Brookhaven National Laboratory)

16:00 Simulation study on attosecond bunch generation using reversed chicane at Argonne Wakefield Accelerator (AWA)

Capability for generating an attosecond bunch can provide interesting opportunities to wakefield accelerator research. We have been studying requirements and challenges in beam dynamics to produce an attosecond bunch using an existing beamline at Argonne Wakefield Accelerator (AWA) facility. One unavoidable limitation of this study is that conventional C-typed chicane is not available. Thus, a modified version of a chicane-like compressor, called a reversed chicane, is designed and running at the AWA facility. AWA’s injector and beamline were simulated using ASTRA and ELEGANT respectively. The study provided guidance toward the attosecond bunch generation. We present the simulation results and propose the modified design and operation conditions to generate the attosecond bunch at AWA facility.

Speaker: Spencer Kelham (Northern Illinois University)

16:00 Simulation study on power loss in the coupling cavity damper of the accelerating π/2 mode for the SuperKEKB ARES cavity

In the SuperKEKB electron-positron collider, the coupled-bunch instability caused by the accelerating mode of RF cavities becomes severe in high beam current. To suppress it, the ARES cavities have been used. The accelerating cavity is coupled with an energy storage cavity via a coupling cavity between them. While the beam is accelerated by the π/2 mode, the parasitic 0 and π modes are damped by a coaxial damper at the coupling cavity without damping the π/2 mode. However, as the beam current becomes higher, some of the accelerating field of the π/2 mode is absorbed by the damper. This is because the π/2-mode field is deformed when two frequency tuners in the accelerating and storage cavities are moved for the optimum tuning condition. This effect increases power load of the damper, which can be an issue at higher beam current. Our high-power test showed that the power loss was higher than a prediction of the equivalent circuit model. Thus, using the CST MW Studio, we simulated the power loss and studied the relation between the power loss and the detuning frequency. We compare the simulation and high-power test results and discuss the possibility of new frequency tuning schemes.

Speaker: Takaaki Yamaguchi (High Energy Accelerator Research Organization)

16:00 Simultaneous electron beam acceleration and compression with a radiofrequency cavity in ultrafast electron diffraction experiments

In ultrafast electron diffraction experiments, the scattering cross-section, q-range, and space-charge effects are critically influenced by the electron beam energy, which is constrained by the high-voltage breakdown. By integrating a 100 kV DC electron gun with a 3 GHz radiofrequency cavity powered with a 400 W amplifier, we demonstrate a net energy gain of up to 31 keV. Here we present simulation and experimental results highlighting the simultaneous compression and accelerating capabilities using a radiofrequency cavity, demonstrating that significant energy gains are attainable without compromising femtosecond scale time resolution.

Speaker: Linus Bölte (TU Dortmund University)

16:00 Specification, design, and production schedule of cryomodule for SRF 5-year plan at KEK

A five-year project (MEXT advanced Accelerator element Technology Development (MEXT-ATD)) funded by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) began at KEK in FY2023. The goal is to manufacture and construct a cryomodule (CM) that satisfies the ILC (International Linear Collider Project) specifications and conduct cooling tests. The 3D model of the cryomodule will be based on the Type-4 CM adopted in the Technical Design Report (TDR) published in 2013, moreover will also reflect the latest technology and experience obtained from the construction and operation of the European XFEL in Europe and LCLS-II in the United States since the TDR. In addition, in anticipation of future prospects, it has been decided that the design and production of every cavity and CM will be based on the refrigeration regulations of the High Pressure Gas Safety (HPGS) Act in Japan. This is first for the iCASA SRF group in KEK. In this presentation, the basic specifications and design of the cryomodule as well as the overall manufacturing schedule and recent progress will be reported in detailed.

Speaker: Yasuchika Yamamoto (High Energy Accelerator Research Organization)

16:00 Studies of resonances limiting the high-brightness LHC beams in the SPS

Space charge effects in combination with betatron resonances limit the performance of high-brightness LHC beams in the CERN Super Proton Synchrotron (SPS). Here we report on experimental studies performed with single-bunch proton beams, monitoring transverse emittance evolution and particle losses while performing tune scans across the horizontal and vertical planes. Two significant resonances were identified: a coupled resonance leading to emittance growth in the horizontal plane and a corresponding emittance decrease in the vertical plane, and another coupled resonance directly associated with particle losses. The resonances identified in these studies could explain the limitations of the beam brightness encountered with the multi-bunch LHC-type beams in the SPS, thus providing valuable insights for the optimization of the high-intensity beams performance.

Speaker: Sofia Kostoglou (European Organization for Nuclear Research)

16:00 Study for limiting factors in transverse wiggler-based arbitrary correlation generation

Recently proposed transverse wiggler is an intriguing tool for imparting designed correlations in phase space. While several simulations have demonstrated its feasibility, the method using the transverse wiggler has several concerns need to be addressed. Beam evolution along the wiggler can introduce errors in the designed correlation. Wiggler fields have strong vertical position dependence, which can introduce unwanted horizontal and vertical couplings. The transverse wiggler generates both horizontal and vertical sinusoidal fields, which can significantly degrade the beam quality. Additionally, its applicability to heavy particles remains uncertain. We will present results from a preliminary study aimed at addressing these concerns.

Speaker: Alex DeSimone (Northern Illinois University)

16:00 Study of operation above half-integer random resonance in the J-PARC RCS

In the 3-GeV Rapid Cycling Synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC), the beam power ramp-up aiming to surpass the design of 1 MW enhances the space charge effect. It pushes the beam toward the structure resonance. To mitigate the beam loss, the operating point is required to be apart from the structure resonance as the beam power ramp-up. However, large beam loss was observed when the operating point was set near the half-integer resonance. Thus, the maximum beam power of the RCS is currently limited so that the beam does not overlap the structure resonance or half-integer random resonance. To address this issue and achieve the beam power ramp-up, we experimentally studied the half-integer resonance compensation using trim quadrupole magnets. In addition, detailed numerical simulations were performed to develop a better understanding. The experimental and numerical results of the operation above half-integer random resonance are presented.

Speaker: Kota Okabe (Japan Atomic Energy Agency)

16:00 Thresholds of longitudinal multi-bunch instabilities in double harmonic RF systems

Multi-bunch instabilities, often driven by narrowband impedance sources such as higher-order modes, present significant intensity limitations in synchrotrons. One approach to mitigate these instabilities is applying a double harmonic radio frequency (RF) system, which can increase the intensity threshold by enlarging the synchrotron frequency spread. In this study, intensity thresholds are calculated for different RF parameters using stability diagrams derived from the Lebedev equation. We analysed configurations and beam characteristics relevant to the synchrotrons at CERN, particularly focusing on the Super Proton Synchrotron (SPS). The semi-analytical results were then compared to macroparticle simulations and measurements. The findings reveal an unexpected beam stabilisation even if a non-monotonic amplitude dependency of the synchrotron frequency is present. Further, techniques for deducing the driving impedance parameters are discussed.

Speaker: Ruben Heine (Technische Universität Berlin)

16:00 Touschek effect in Super Charm Tau factory

Super Charm Tau factory is a proposed electron-positron double ring collider with crab waist collision scheme operating in wide beam energy range from 1.5 GeV to 3.5 GeV with peak luminosity of 10^35 cm^(-2) s^(-1). The polarized electron source and three Siberian Snakes provide 80% longitudinally polarized electron beam at 2 GeV. Superconducting wigglers decrease damping times, effects of intra-beam scattering and increase Touschek beam lifetime, particularly at low energy.
This work presents studies of the Touschek effect in SCTF, as well as the results of a simulation of Touschek scattering, MOGA optimization of local momentum acceptance, and an investigation into the dependence of the dynamic aperture and the Touschek lifetime on the average orbit error.

Speaker: Mr Mikhail Skamarokha (Budker Institute of Nuclear Physics, Synchrotron Radiation Facility — Siberian Circular Photon Source «SKIF» Boreskov Institute of Catalysis)

16:00 Touschek lifetime and periodic beam loading effect in the storage ring of SRF "SKIF"

The collective effects observed in storage rings with high-intensity beams are numerous and diverse. One such effect is that of periodic beam loading of accelerating RF cavities. This effect is contingent upon the impedance of the fundamental mode of the RF cavities and the mode of filling pattern. In a multitude of configurations, the periodic beam loading effect in storage rings leads to a change in the Touschek lifetime along the beam. This work is dedicated to the calculation of this effect in the storage ring of SRF "SKIF", a novel fourth-generation synchrotron radiation source currently under construction in Novosibirsk. Analytical calculations of this effect have been carried out for the main filling mode of the storage ring. It has been demonstrated that bunches in this regime can exhibit significantly disparate Touschek lifetimes. Furthermore, it has been shown that the effect is negligible when the RF acceptance is equal to the energy acceptance of the storage ring.

Speaker: Mikhail Baistrukov (Budker Institute of Nuclear Physics)

16:00 Understanding superconducting cavities through the least action principle

Superconducting cavities are indispensable elements in modern particle accelerators, utilizing the ultra-low sur-face resistance of superconductors to achieve exceptionally high quality factors. In this work, we apply the least action principle to derive an equivalent RLC circuit model, offering a unified theoretical framework to describe the electromagnetic behavior of superconducting cavities. Beyond the classical model, we examine the underlying heat dissipation mechanisms and identify quantized physical quantities that influence cavity performance. Particular attention is given to the quantum aspects of the quality factor, including its manifestation in decay time measurements. By bridging classical electrodynamics and quantum dissipation, this study provides a deeper under-standing of the fundamental principles governing super-conducting cavity dynamics.

Speaker: Heetae Kim (Institute for Basic Science)

16:00 Update on multi-objective genetic optimizations of the photoinjector for CARIE

We present updated simulation results on the maximum brightness achievable by a 1.6-cell cold copper C-band photoinjector, designed for testing and commissioning as part of the Cathodes and RF in Extremes project at Los Alamos National Laboratory. Previous simulations highlighted the high brightness attainable with a 250 pC bunch charge, attributed to the high accelerating gradients and the benefits of a radially symmetrized photoinjector design. However, these earlier simulations relied on idealized temporal beam profiles, overlooked the temporal evolution of the gradients, and did not account for the influence of cathode plug geometry on the gradients—factors that significantly affect the maximum achievable brightness. In this work, we report the results of Multi-Objective Genetic Optimizations that incorporate more realistic temporal beam profiles and gradients, accounting for both the cathode plug geometry and the effects of time-dependent gradient evolution.

Speaker: Evgenya Simakov (Los Alamos National Laboratory)

16:00 Updates to the differentiable accelerator simulation code Cheetah

The design and operation of modern accelerators demand advanced simulation tools capable of addressing complex challenges. Differentiable simulations are particularly valuable, as they enable gradient-based optimization techniques that significantly reduce computational costs and efficiently tackle high-dimensional problems. The PyTorch-based simulation code Cheetah was developed to combine high-speed, differentiable simulations with seamless integration into machine learning workflows. In this work, we present recent updates to Cheetah, developed collaboratively by DESY, KIT, SLAC, and LBNL, which extend its capabilities and enhance its performance. Key advancements include support for vectorized execution, enabling simultaneous simulations across large parameter spaces; the addition of space charge modeling and higher-order transfer maps for more accurate beam dynamics; and expanded support for multiple particle species and additional accelerator components, broadening its applicability to other systems. By enabling faster, more precise, and scalable simulations, Cheetah is poised to become a valuable tool for meeting the growing demands of the accelerator physics community.

Speaker: Andrea Santamaria Garcia (Karlsruhe Institute of Technology)

16:00 Wakefield and HOMs preliminary characterization of the four-quadrant multi-cell RF accelerating structure for the ASTERIX project

The goal of the ASTERIX project, proposed at INFN-LNF and funded by the CSN5, is the first-time demonstration of a practical, meter-long X-band RF structure for real linear accelerators made of hard copper and four quadrants. Our joining technique will be the TIG welding for the prototype. During the feasibility study, in the first year, we will proceed to the RF cavity design of two full structures (~ 1m long and ~100 cells), one with optimized geometry for single-bunch and the other one for multi-bunch operation. We will perform the RF design optimization, including thermo-mechanical analysis, of the multi-cell TW cavity and the RF mode-launcher (which will be integrated with the cavity in the most compact way possible) for both structures’ geometries. In this paper, we show the preliminary characterization of the higher-order modes (HOMs) and wake-fields, which are detrimental for the particle beam with high-quality parameters typically accelerated in such structures, in the case of single-bunch operation. The electromagnetic designs will be performed by using the 3D numerical codes Ansys-HFSS and CST-Microwave Studio.

Speaker: Giuseppe Torrisi (Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud)

16:00 Wakefield effects on dynamic aperture during RCS bunch merges

In order to achieve the necessary bunch charge, the Rapid Cycling Synchrotron utilizes bunch merging. The altered longitudinal motion during merges has the potential to reduce dynamic aperture and cause emittance growth. Tools for analyzing the effects of merging have been developed for the AGS using Bmad and a simplified tracking code in Julia. These tools are applied to the merges of the RCS, altered to include the important effects of wakefields. In this paper, dynamic aperture and emittance growth for current RCS merge parameters and their effective operational limits are analyzed.

Speaker: Jonathan Unger (Cornell University (CLASSE))

Thursday 5 June

09:00 → 09:30 THXD:Novel Particle Sources and Acceleration Techniques (Invited)

Convener: Enrica Chiadroni (Sapienza University of Rome)

09:00 Guiding of charged particle beams in curved plasma-discharge capillaries

A new approach that demonstrates the guiding of relativistic electron beams over curved paths by means of a plasma-discharge capillary is presented. The magnetic field produced by the discharge current is used to deflect and focus the beam along a curved capillary, showing that the guiding can be made dispersion-less, i.e. not affected by chromatic dispersion. This proof-of-principle experiment extends the use of plasma-based devices that revolutionised the field of particle accelerators enabling the generation of GeV beams in few centimeters. Compared to state-of-the-art technology based on conventional bending magnets and quadrupole lenses, these results provide a compact and affordable solution for the development of next-generation table-top facilities.

Speaker: Riccardo Pompili (Istituto Nazionale di Fisica Nucleare)

09:00 → 09:30 THXN:Beam Dynamics and EM Fields (Invited)

Convener: Mamad Eshraqi (European Spallation Source)

09:00 Review of beam based correction and optimisation for accelerators

Improving the performances of modern circular particle accelerators requires a tight and solid control of its linear optics. Decades of developments provided invaluable tools towards this end. This talk will review the historical milestones and the most recents novelties in this field.

Speaker: Xiaobiao Huang (SLAC National Accelerator Laboratory)

09:30 → 10:30 THAD:Novel Particle Sources and Acceleration Techniques (Contributed)

Convener: Enrica Chiadroni (Sapienza University of Rome)

09:30 Progress on experimental demonstration of high-power generation from 0.4 THz corrugated structure

A collaboration is underway to develop and demonstrate GW-level power generation in the sub-THz frequency range. Two key components--wakefield structure and electron bunch train--were prepared for the demonstration. A 5-cm long corrugated structure was fabricated using two thin metallic plates with through-holes of different inner diameters. The plates were fabricated by lithography and bonded by high-pressure, high-temperature boding process. The fabricated structure, whose fundamental mode frequency is 0.4 THz, was powered by an electron bunch train with 16 bunches (1 nC per bunch). Efforts are ongoing to achieve results comparable to simulations, targeting a peak power of 3 GW and a maximum deceleration field of 700 MV/m within the bunch. We present the most recent experimental results.

Speaker: MinKyu Seo (Korea University Sejong Campus)

09:50 A method for measuring energy gain with variable plasma length at AWAKE

The Advanced Wakefield (AWAKE) experiment is a proof-of-principle accelerator facility at CERN (Geneva, Switzerland). Proton bunches from the CERN Super Proton Synchrotron are used to drive wakefields in 10 metres of laser-ionised rubidium plasma, over which externally injected 19 MeV electrons are accelerated. Run 1 of AWAKE successfully demonstrated the self-modulation of the long proton bunch, and the acceleration of electrons to 2 GeV. Upgrades to the rubidium vapour source during Run 2 have enabled the use of a plasma density step, and variation of the plasma length through the insertion of foils along the source to dump the laser pulse. When placed suitably within the development of self-modulation, the density step is expected to preserve the wakefield amplitude, and therefore accelerating gradient, over longer distances than with uniform plasma. This work presents the first measurements of electron acceleration with a density step, studied as a function of the plasma length.

Speaker: Fern Pannell (University College London)

10:10 Development of cold atom electron source in KEK

A ultra-low emittance electron source utilizing laser-cooled neutral gas as the photo-ionization source has been developed in several laboratories in the accelerator community. We have started the development aiming for using the electron source for the injector of a THz accelerator which has a small aperture and requires a high quality beam.
We have developed the electron source system, i.e. the laser system for laser-cooling, the vacuum chamber equipped with the acceleration electrodes and necessary viewing ports for laser access, the ionization laser system, and the diagnostic system for the electron beam.
We will show the present status of the work and discuss the future prospect.

Speaker: Yosuke Honda (High Energy Accelerator Research Organization)

09:30 → 10:30 THAN:Beam Dynamics and EM Fields (Contributed)

Convener: Mamad Eshraqi (European Spallation Source)

09:30 Assessing the origin of the LHC beam halo

Measurements of the transverse beam-halo population at large amplitudes in the Large Hadron Collider (LHC) provide crucial insights into the stored beam energy near the LHC collimators. These particles do not contribute significantly to the luminosity but their loss could impose limitations on accelerator performance through sudden loss spikes or even collimator damage in case of fast beam failures. A thorough understanding of the beam halo formation, along with the physical mechanisms driving its behaviour and evolution throughout the final stage of the LHC injection chain and during the acceleration cycle, is essential to define appropriate mitigation strategies to ensure reliable operation in view of High Luminosity LHC beam parameters. In this study, we explore potential origins of the transverse beam halo by examining experimentally multiple contributing factors to halo formation, including electron cloud effects, beam injection dynamics from the Super Proton Synchrotron (SPS), and the energy ramping process within the LHC.

Speaker: Pascal Hermes (European Organization for Nuclear Research)

09:50 Coherent stability and dynamic aperture with strong space charge for the FAIR SIS100 synchrotron

Employing octupole magnets for Landau damping of transverse single-bunch instabilities in synchrotrons often restricts the dynamic aperture due to the excitation of betatron resonances. The situation complicates in the presence of strong direct space charge fields. A notable case is the 1-second accumulation plateau of the heavy-ion synchrotron SIS100 at the Facility of Antiproton and Ion Research (FAIR), which is designed to operate at beam intensities near the space charge limit. This study presents numerical simulations that establish the proposed stabilisation scheme, incorporating self-consistent space charge effects, beam coupling impedance and full lattice tracking. The analysis combines requirements for Landau damping of the resistive-wall instability and tolerable octupole current in relation to dynamic aperture. The results demonstrate effective control of collective effects for the most demanding beam production scheme with ${}^{238}$U${}^{28+}$ beams.

Speaker: Adrian Oeftiger (University of Oxford, John Adams Institute for Accelerator Science)

10:10 Dynamic dipole kick due to a rippling sextupole

Eddy currents induced by rippling magnets in axially asymmetric vacuum chambers are known to generate magnetic multipoles of higher orders, with a dynamic sextupole driven by a time-varying dipole being a common example. However, the inverse phenomenon—lower-order multipoles created by an oscillating higher-order multipole magnet, though consistent with Maxwell’s equations—has not been explored to our knowledge. In this paper, we present an analytical derivation of the kick for the driving magnetic multipole of any order and the vacuum chamber of arbitrary shape. We then validate our findings using FEM simulations. Finally, we demonstrate the relevance of this effect to the Electron Storage Ring (ESR) of the Electron-Ion Collider. The ESR has very stringent orbit stability requirements at the interaction point, which demand rigorous evaluation of all potential dipolar kick contributions. Our findings reveal that the dipolar kicks generated by rippling sextupoles are sufficiently strong to require the ESR sextupole power supply ripple specification to be tightened from an otherwise sufficient 100 parts per million (ppm) rms to 20 ppm.

Speaker: Boris Podobedov (Brookhaven National Laboratory)

10:30 → 11:00 Coffee Break

11:00 → 11:30 THYD:Beam Instrumentation and Controls, Feedback and Operational Aspects (Invited)

Convener: Eric Prebys (University of California, Davis)

11:00 Reinforcement learning in particle accelerators

Reinforcement learning (RL) is a unique learning paradigm inspired by the behaviour of animals and humans to learn to solve tasks autonomously. Learning occurs through interactions with an environment, exploring, and evaluating strategies under various conditions. RL excels in complex environments, can handle delayed consequences, and is able to learn solely from experience without access to an explicit model of the system. This makes RL particularly promising for particle accelerators, where the dynamic conditions of particle beams and accelerator systems require continuous adaptation, and modelling is challenging. Although RL applications are emerging in accelerator physics and showing promising results, their widespread introduction faces critical challenges. Among the main obstacles are the effective formulation of control problems, training, and the deployment of solutions in real systems. This paper provides an overview of the potential of RL in accelerator applications, highlighting current challenges and future research directions.

Speaker: Dr Andrea Santamaria Garcia (University of Liverpool)

11:00 → 11:30 THYN:Hadron Accelerators (Invited)

Convener: Prapong Klysubun (Synchrotron Light Research Institute)

11:00 Deceleration of ion beams - Related challenges and opportunities

The GSI facilities of CRYRING and HiTRAP are used for decelerating ion beams to low energies. This deceleration phase is preceded by the generation and acceleration of those ions. CRYRING and HiTRAP operate at the junction between accelerator science and atomic physics. The scientfic motivation, the operation principle, the state of the art and future outlooks are presented.

Speaker: Frank Herfurth (GSI Helmholtz Centre for Heavy Ion Research)

11:30 → 12:10 THBD:Beam Instrumentation and Controls, Feedback and Operational Aspects (Contributed)

11:30 Development of an RFSoC-based low-level RF controller for an electron linac

We are developing a low-level RF (LLRF) controller based on RF System on Chip (RFSoC) for an electron linac. The AMD Zynq RFSoC was employed for this controller, which has a large-scale high-speed FPGA together with high-speed ADCs and DACs (8 channels each). The RFSoC also has an application CPU for Linux and a real-time CPU for time-critical tasks, capable of a 1 kHz repetition rate. A general-purpose pizza-box module with an RFSoC was designed and manufactured, and firmware for LLRF control was developed. This LLRF module will be first utilized for an X-band (11.424 GHz) transverse deflector system* for SACLA. A pulsed X-band RF signal is generated by upconverting a 476 MHz IF signal from the DAC and RF signals from the X-band high-power components are converted to 476 MHz IF signals and digitized by ADCs. The IF signal is converted to a baseband IQ signal and the phase and amplitude are obtained. Since the latency of ADC, DAC, and FPGA is as short as several 100 ns, the intra-pulse feedback control is anticipated to stabilize the phase and amplitude of the acceleration RF field. This presentation will give the design and basic performance of the LLRF controller.

Speaker: Hirokazu Maesaka (RIKEN SPring-8 Center)

11:50 Development of non-invasive beam diagnostics by quantum optics-based detection

We report our latest progress developing diagnostics using quantum optics-based detection method for determining the spatial properties and current of electron beams. As electrons pass through a dilute vapor of rubidium atoms, their electric and magnetic field perturb quantum states of Rb atoms and change their optical properties. By measuring the polarization rotation due to electron current, we can recreate a 2D projection of the electrons’ magnetic field and determine the electron beam position, size and total current. Our experiment using a 10 ~ 20 keV/110 uA electron beam shows this approach is insensitive to electron energy.
Alternatively, using quantum superpositions including highly excited Rydberg states of Rb atoms, we can also measure electric field generated by a travelling electron beam. We reconstructed a 2D profile of a 20 keV/150 uA electron beam and measured its current.
These complimentary methods can be particularly useful for real time non-invasive spatial and current characterization of high energy and high current charged particle beams used in various particle accelerators and nuclear physics research.

Speaker: Shukui Zhang (Thomas Jefferson National Accelerator Facility)

11:30 → 12:10 THBN:Hadron Accelerators (Contributed)

Convener: Prapong Klysubun (Synchrotron Light Research Institute)

11:30 Commissioning 1.7 MW, 1.3 GeV beam for the proton power upgrade at SNS

With a total project cost of $272 million the recently completed Proton Power Upgrade at the Spallation Neutron Source increased accelerator capability from 1.4 to 2.8 MW, and the first target station from 1.4 to 2.0 MW. 700 kW of beam power will eventually be sent to the Second Target Station. PPU installed 7 high-beta cryomodules, and HPRF to increase the H- linac energy from 1.0 to 1.3 GeV, three new magnets in the accumulator ring to transport 1.3 GeV beam, upgraded utilities throughout the facility, and a new 2.0 MW target design, as well as additional equipment. Installed over several years during semi-annual maintenance outages, equipment was commissioned as it became available. A final PPU-driven 9-month outage began in August 2023 to install the balance of the equipment, and build a tunnel stub that will eventually be extended for the Second Target Station. Following this long outage, SNS was operated at 1.3 GeV for the first time. This presentation will describe the beam commissioning activities following the long outage, and subsequent run, during which the SNS was operated at 1.7 MW on target at 1.3 GeV for 2062 hrs.

Speaker: Nicholas Evans (Oak Ridge National Laboratory)

11:50 FAIR commissioning - Towards first science

The international Facility for Antiproton and Ion Research (FAIR) is under construction at the GSI Helmholtz Centre in Darmstadt. The first project stage includes the superconducting 100 Tm heavy-ion synchrotron SIS100, the Super Fragment Separator, and associated beam transport lines. Part of GSI’s existing accelerator chain, comprising UNILAC and SIS18, will serve as injector. Installation work in the FAIR accelerator tunnels and supply buildings has been ongoing since early 2024. As progress continues, special attention is now on the start of commissioning, beginning in 2025 with the cryogenic plant. Commissioning of the transport line will follow at the end of 2025, and beam commissioning is scheduled for the second half of 2027. This paper outlines the current status of the project, commissioning strategy and timeline.

Speaker: Stephan Reimann (GSI Helmholtz Centre for Heavy Ion Research, Facility for Antiproton and Ion Research)

12:10 → 13:30 Lunch

13:30 → 15:00 THWD Award Session

Convener: In Soo Ko (Pohang Accelerator Laboratory)

13:30 Memorable Research and Development

Xie Jialin Prize
The ACFA Xie Jialin Prize for exceptional work in the accelerator field has been given to Hitoshi Tanaka, deputy director of RIKEN SPring-8 Center, for his many contributions to linear and circular accelerator-based photon sources. Examples of his works include: girder-based magnet alignment suppressing COD sensitivity against magnet mis-alignment; achievement of the transparent top-up operation at SPring-8; accelerator system design of the world first compact XFEL, SACLA; green upgrade concept of SPring-8 combining high beam performance with energy saving; and his leading role in design, commissioning and performance upgrade of accelerators at the SPring-8 campus.

Speaker: Hitoshi Tanaka (RIKEN SPring-8 Center)

13:50 Advanced ECR ion source development for the production of intense highly charged heavy ion beams and the applications

Nishikawa Tetsuji Prize
Nishikawa Tetsuji Prize for his significant contribution to high performance high charge state ECR ion source development, especially in the domain of the next generation ECR ion source development, superconducting ECR ion source high performance operation and key technologies development.

Speaker: Liangting Sun (Institute of Modern Physics, Chinese Academy of Sciences)

14:10 Plasmas and accelerators: lessons learned

Hogil Kim Prize
Riccardo Pompili got his PhD in Physics in 2013 at the University of Rome “Tor Vergata” with a thesis related to the development of an Electro-Optical Sampling diagnostics conceived for beamdriven plasma wakefield accelerators. For his PhD thesis he was awarded in 2014 by the “Young Scientist Prize” of the Italian Synchrotron Light Society. Currently he is the scientific coordinator of the SPARC_LAB accelerator activities and leader of Plasma Working Area for the EuPRAXIA@SPARC_LAB project. During his scientific career he got broad experience in accelerators and plasma physics witnessed by several pioneering works published as corresponding author.

Speaker: Riccardo Pompili (Istituto Nazionale di Fisica Nucleare)

14:30 Novel Fixed Field Accelerator Approaches for Hadron Therapy: Extraction, Transport, and Delivery

Mark Oliphant Prize
Adam’s work focuses on the application of Fixed Field Accelerator technologies to hadron therapy, investigating novel techniques for beam extraction, transport, and delivery. He completed the initial design study for a large energy acceptance beamline technology demonstrator as part of the ‘TURBO’ project at Melbourne University, looking at both beam optics and magnet design methodologies. This beamline can simultaneously transport beams with a momentum spread >±40%, which has the potential to make treatments more efficient and effective. He is now a research fellow at The University of Melbourne, where he continues to work on TURBO as well as other projects.

Speaker: Adam Steinberg (The University of Melbourne, Manchester University)

14:50 Best Student Poster Award

15:00 → 15:30 THED Entertainment Session

Convener: Jui-Che Huang (National Synchrotron Radiation Research Center)

15:00 Why Did My Ancestors Leave Taiwan?

15:30 → 17:30 Thursday Poster Session: THPB

Thursday Poster Session

15:30 A helium-cooled target design for the SPS Beam Dump Facility (BDF) at CERN

CERN’s upcoming SPS Beam Dump Facility (BDF) will host a production target designed to manage challenging thermal and mechanical conditions while providing the physics output required by the Search for Hidden Particles (SHiP) experiment. It must fully absorb 400 GeV/c protons and dissipate up to 305 kW. The baseline design consists of water-cooled tantalum-alloy clad TZM and tungsten (W) blocks. Challenges for the maintenance and reliability of the baseline design led to the development of alternative concepts. The leading design—a helium-cooled W target—optimizes thermal management and structural integrity while simplifying the manufacturing and improving its physics performance for the SHiP experiment. The experimental validation of this concept will be via testing multiple prototypes in an existing slow beam extraction test bench at CERN’s North Area.
In parallel, extensive R&D is being pursued on: properties of pure W products including hot-rolled plates; manufacturing of seamless blocks; W-W diffusion bonding techniques.
This contribution includes an overview of the helium-cooled target design and a summary of the ongoing material characterization, prototyping and beam-tests.

Speaker: Alvaro Romero Francia (European Organization for Nuclear Research)

15:30 A novel approach to qualify the straightness of electrostatic septa for the SPS slow extraction

The quality of slow extraction from the SPS (Super Proton
Synchrotron) to the North Area is critically influenced by
the straightness tolerance of the electrostatic septum. Past
observations have identified a degradation of the anode body
straightness, resulting in an increased beam loss during ex-
traction. A new metrology bench including optical sensors
has been developed to cope with the tolerance requirements
while also allowing process automation. Two distinct mea-
surement procedures are currently employed: one for the
anode noses and another for the individual wire metrology. A
control system was developed to automate the metrology and
analysis process, allowing operator and time-independent
measurements and increasing process accuracy. The find-
ings from these investigations provide accurate information
in case corrective machining of the anode body is required.
The metrology method and the described nose scan approach
will further reduce beam loss during the slow extraction pro-
cess.

Speaker: Laurent Ducimetière (European Organization for Nuclear Research)

15:30 A radiation-resistant distributed temperature sensor for CERN’s accelerators

Optical Fibre Sensors (OFS) possess unique features, such as high sensitivity, versatility, and the ability to operate in harsh radiation environments. Distributed OFS are notable for enabling real-time monitoring over large-scale facilities, making them ideal for applications in particle accelerators. Their distributed measurement capabilities provide comprehensive monitoring while offering a cost-effective alternative to conventional pointwise technologies. As part of the Innovation work package of CERN’s Personnel Safety System Consolidation program, an experimental study was conducted to characterize the performance of a radiation-hard Distributed Temperature Sensor (DTS) to complement CERN’s safety systems, addressing cryogenic leaks and fire risks. Several fire tests were performed to assess the sensor's accuracy and temporal response under emergency-like conditions. A phenomenological model was derived from these tests to predict the system's behaviour in real-world scenarios. The obtained results are key to the first deployment and operation of a dedicated DTS demonstrator in a part of the LHC in 2025.

Speaker: DIEGO DI FRANCESCA (European Organization for Nuclear Research)

15:30 A vibrating wire system for multipole magnets alignment in TPS

An auto-scanning vibrating wire system for magnets centering alignment was developed at NSRRC. It is prepared for the replacement of magnets on the girder of TPS storage ring in case of malfunction and also as a pre-study topic of the TPS upgrade. With this system, both quadrupole and sextupole magnets were tested in the laboratory. This paper presents the system configuration and testing results.

Speaker: Tse-Chuan Tseng (National Synchrotron Radiation Research Center)

15:30 Accelerator test facility upgrades to enable further advancements in the science and technology of accelerators

The Accelerator Test Facility* (ATF) is the DoE Office of Science User Facility aimed to provide users with a high brightness electron beam, near-infrared (NIR), and long-wave infrared (LWIR) laser beams. The unique capabilities at the ATF include the possibility to combine the electron beam with synchronized high-power laser beams.
It is planned to upgrade the facility to have enhanced capabilities. They will include: an increased electron beam energy from the present 65-70 MeV to 110-120 MeV; a reduced by a factor of about 10 phase jitter; and an improved - to femtoseconds’ scale - time synchronization between the electron beam and the laser beams. To accomplish these tasks, the ATF will design and deploy a new High Level RF System, a new Low Level RF System, and a new Time Distribution System. In addition, the ATF will change the Power Plant for the quadrupole and correction magnets to increase operations’ reliability. It is expected that the planning stage will be completed in about 3 years, and the actual hardware deployment will be finished after that in the next 2 years. Different upgrade options are being investigated now and are described in the presented article.

Speaker: Mikhail Polyanskiy (Brookhaven National Laboratory)

15:30 An evaluation of collimation settings for the High Luminosity LHC baseline

In the context of the High Luminosity Large Hadron Collider (HL-LHC) project, two configurations of collimator settings are being considered. A set of relaxed settings were conceived to address potential limitations due to the impedance contribution of the collimation system with the initially foreseen settings, and to increase the
primary betatron cut in case of over-populated beam tails. A significant simulation campaign has been conducted, utilising Xsuite-FLUKA coupling for the first time, to estimate the cleaning performance for each of these settings with the latest optics and layout scenarios. In addition, experiments in the current LHC have been carried out to experimentally study the cleaning performance with HL-LHC settings and to
validate the simulated predictions. This paper presents and examines the results of these studies, aiming to determine which collimation settings are more suitable for implementation.

Speaker: Bjorn Lindstrom (European Organization for Nuclear Research)

15:30 Antechamber type vacuum chamber coated with non-evaporable getter films

To coat the inner surface of antechamber type vacuum chamber for Hefei Advanced Light Facility (HALF) with nonevaporable getter material (NEG), 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.

Speakers: Wenli Zhang (University of Science and Technology of China), Dr Baoyuan Bian (High Energy Accelerator Research Organization)

15:30 Architecture reconstruction and optimization of front-end interlock system in TPS

The Front-End Interlock System in the Taiwan Photon Source (TPS) has been upgraded to address deployment complexity and maintainability issues observed during early operations. To improve dependability and fault handling, the system integrates a redundant dual-CPU PLC and incorporates a real-time operating system (RTOS) to optimize status and signal publishing processes. While preserving compatibility with the legacy system, the new design streamlines the architecture, improves diagnostic efficiency, and expedites deployment for future upgrades.

15:30 CFD thermal studies of the air inside the storage ring tunnel of the ALBA synchrotron light source for the 3rd and 4th generation designs

The ALBA Synchrotron is currently designing its new version to become a 4th generation particle accelerator. In this new scenario, ALBA would produce a brighter and more coherent photon beam. As a result, ALBA would provide capabilities hitherto inaccessible in terms of resolution, detection levels and understanding of chemical and electromagnetic properties.
In this context, the thermal and geometric conditions inside the tunnel will be modified, specifically the Storage Ring. The Booster Ring, Transfer Lines, Air Conditioning System and the tunnel itself will not be modified.
The prediction of the thermal behaviour of the air inside the tunnel for the 4th generation is essential, considering the influence of the stability of the air temperature on the stability of the electron beam orbit. The present work assesses Computational Fluid Dynamics (CFD) studies of the air inside both the current and the 4th generation ALBA tunnel. Comparative studies of the temperature distribution in the air are performed and proposals for the optimization of the air conditioning system are presented. The studies are based on the FLUENT software of ANSYS WORKBENCH.

Speaker: Dr Marcos Quispe (ALBA Synchrotron (Spain))

15:30 Compiling a life cycle inventory of a large accelerator facility: The ISIS-II neutron and muon source life cycle assessment

The ISIS-II Neutron and Muon Source, the proposed successor to the ISIS Neutron and Muon Source at the Rutherford Appleton Laboratory, UK, presents a unique opportunity to integrate environmental sustainability practises from its inception. A Life Cycle Assessment (LCA) was performed during the early feasibility and design stage to evaluate the potential environmental impacts across construction, operation, and decommissioning phases, and to identify opportunities for impact reduction.
With many accelerator components, elements and systems still in early optioneering stages, numerous assumptions were required to model the facility. This work explores these assumptions and the use of a simplified LCA framework, focusing on bulk material selection, future operational resource management, and strategies for managing non-radioactive and radioactive materials at decommissioning. Updated results of the LCA and identified strategies to minimize and mitigate negative environmental impacts are presented, emphasizing the role of LCAs in embedding sustainability into decision-making for large-scale scientific facilities.

Speaker: Dr Hannah Wakeling (John Adams Institute)

15:30 Comprehensive power consumption profiling of KARA for sustainable operations

The negative impacts of global warming and continuously rising energy costs emphasize a need for sustainable and cost-effective operation also for accelerator facilities. This necessitates optimization of accelerator operation, which then requires a comprehensive profiling of accelerator facilities for power consumption patterns to break down the consumption trends of the whole facility. At KIT, as part of the Horizon Europe project Research Facility 2.0, a comprehensive analysis of the Karlsruhe Research Accelerator (KARA) was carried out using the past 1 year of power consumption profiles for all accelerator components. This contribution provides an analysis to identify the overall power consumption profiles of KARA’s main systems, such as the storage ring, cooling plants, and beam-lines. It also explores correlations with factors like weather and temporal variation in consumption patterns on a quarterly, monthly, weekly, and daily basis. The results highlight peak power consumers and consumption periods, as well as the influence of seasonal behavior, accelerator operation modes, and weather patterns.

Speaker: Mahshid Mohammad Zadeh (Karlsruhe Institute of Technology)

15:30 Conceptual design and optimization of a liquid lead circuit as beamstrahlung absorber for the CERN’s FCC

Beamstrahlung radiation represents a new challenge at CERN's lepton Future Circular Collider (FCC-ee), specifically for electron-positron collisions. At each interaction point, its unprecedented beam intensities give rise to two photon beams with a power of several hundred kW each. Liquid lead, known for its high density and Z and relatively low melting point, is proposed as a beam dump material to safely dispose of this power. Achieving the necessary effective interaction thickness of 10 to 20 cm presents challenges in optimizing both mass flow rates and the geometric configuration of the lead. This study employs the Monte Carlo code FLUKA to simulate energy deposition and thermal simulations to investigate multiphase flow dynamics within an open-channel configuration. Various slope designs for a free-flowing liquid lead stream within an argon-filled vessel are explored to prevent oxidation. By optimizing the slope and shape of the lead flow, this work seeks to enhance energy absorption and thermal management, improving the effectiveness of liquid lead in high-power beam dump applications.

Speaker: Silvio Candido (European Organization for Nuclear Research)

15:30 Conceptual design of the vacuum system of cSTART

The Karlsruhe Institute of Technology (KIT) operates research accelerator facilities for the development of new technologies for future compact light sources at the Institute for Beam Physics and Technology (IPBT). Within the cSTART project (compact STorage ring for Accelerator Research and Technology), a Very Large Acceptance compact Storage Ring will be realized to combine a compact storage ring and a laser-plasma accelerator. The new design, based on 45° bending magnets, is suitable to store a wide momentum spread beam. Good vacuum conditions are essential for the successful operation of such an accelerator system. In our case, a final pressure of <1E-8 mbar is required. For cSTART, special care was taken to find a compact (43 m circumference), space- and cost-saving, yet efficient vacuum system design that fulfils this requirement. This article presents the vacuum concept that will be used at cSTART. This includes the selection of vacuum components, the design of the vacuum chamber and vacuum simulations.

Speaker: Michael Nasse (Karlsruhe Institute of Technology)

15:30 Copper vacuum chamber of HALF storage ring coated with NEG

The premise of the stable operation of charged particles in the accelerator storage ring is a stable and clean vacuum environment, and the level reached by the vacuum system is directly related to beam intensity, beam quality and beam lifetime. Therefore, the design of vacuum system is an indispensable part of accelerator engineering. HALF is a fourth generation advanced synchrotron radiation light source in low energy region. The beam emittance in the storage ring reaches the diffraction limit. At present, the circumference of the storage ring as the main body of HALF is 480m and is set to 20 cycles. According to the characteristics of the fourth generation light source storage ring, such as small vacuum chamber space, large calorific value, small flow conductivity of the storage ring and limited effective pumping speed of the vacuum pump, the alloy copper with high strength, good thermal conductivity and non-magnetic should be selected as the main material of the ring vacuum chamber. At the same time, the exhaust of intermittent sputtering ion pump can not meet the requirement of vacuum, so the inner surface of copper vacuum chamber of storage ring must be coated with NEG film.

Speaker: Xinming Song (University of Science and Technology of China)

15:30 Current status of permanent magnet radiation resiliency studies at CEBAF

One possible future for Jefferson Lab’s Continuous Electron Beam Accelerator Facility (CEBAF) lies in upgrading its maximum nominal energy using Fixed-Field Alternating-gradient (FFA) technology for its recirculating arcs. The current proposal aims to use permanent magnets to supply the fixed fields. One concern among reviewers is the degradation of these permanent magnets during operation due to the radiation environment in which they will be present. This work, funded by a Laboratory Directed R&D grant, aims to measure the magnet degradation in the CEBAF tunnel enclosure, and extrapolate to the energies expected from the upgrade. We present the latest results of this study, as well as plans moving forward.

Speaker: Stewart Boogert (Cockcroft Institute)

15:30 Data fusion based on the symmetric dual-path laser uncertainty weighting method

The construction of fourth-generation accelerators, represented by free-electron lasers and diffraction-limited storage rings, is increasingly popular, which sets higher standards for the installation precision of insertion devices. Large-scale insertion devices are installed using two laser trackers, but a rigorous system has not been established. To enhance installation accuracy, we propose a symmetric uncertainty weighting fusion method. This method integrates the data from two laser trackers with uncertainty weighting through symmetric coordinate transformation, thereby establishing a dual-route laser system. According to actual measurement and simulation results, it has been proven that this method can effectively improve the precision of coordinate system recovery, reduce deviations from theoretical values, and thereby enhance installation precision.

Speaker: Ting Ding (University of Science and Technology of China)

15:30 Design and construction of a permanent magnet quadrupole at NSRRC

Increasingly, synchrotron facilities are being developed as green accelerators focused on energy efficiency and low-emittance rings to achieve high brilliance. The emittance size of the electron beam is closely related to the number of bending magnets used. To economically upgrade and optimize the current synchrotron facility, it is crucial to minimize revisions to the existing infrastructure. As a result, more lattice magnets should be installed within the previously constrained achromat space to maximize the available area for the straight section. Consequently, permanent magnet technology offers significant advantages due to its compactness, lack of power consumption, and elimination of the need for cooling circuits with deionized water. This study presents the design of a hybrid-type permanent magnet quadrupole, which consists of permanent magnets and soft magnetic materials, similar to the hybrid configuration of insertion devices. The model, with a bore radius of 11.5 mm, achieves a magnetic field gradient exceeding 90 T/m. Additionally, the practical engineering process used to realize this design is described. Finally, the magnetic field performance is characterized.

Speaker: Cheng-Hsing Chang (National Synchrotron Radiation Research Center)

15:30 Design and first prototype results of PETRA-IV permanent magnet dipole-quadrupoles

Permanent magnet-based dipoles will be an essential part of the future PETRA-IV light source at DESY. The bending magnets are combined-function DQ-magnets, which provide moderate focusing with a B/G ratio of about 0.03m. Each DQ consists of several C-shaped modules, one of the three types additionally having a stepwise longitudinal gradient. Several prototype modules have recently been manufactured. The paper describes the magnet design, compares manufacturing peculiarities, and discusses first magnetic measurement results.

Speaker: Markus Tischer (Deutsches Elektronen-Synchrotron DESY)

15:30 Design and structural analysis of a bending chamber for EPU applications in the SPS-II storage ring

Designing a vacuum chamber for the Elliptically Polarized Undulator (EPU) in the SPS-II storage ring presents challenges due to a constrained bore aperture, minimal clearance between magnet poles, and requirements for synchrotron radiation delivery. This study focuses on a vacuum chamber design that accommodates the large opening angle necessary for EPU operation. A complex transition cross-section was developed to achieve the required beam aperture while maintaining compatibility with the magnet structure. The limited clearance of 0.5 mm between the chamber and magnets necessitates precision machining and fabrication. Structural reinforcements were added to the thin sections of the chamber to ensure mechanical stability, and a specialized welding approach was implemented to minimize deformation. The chamber is fixed to supports designed to control thermal deformation during operation. Finite element analysis (FEA) evaluates the chamber’s structural performance, including stress, safety factors, and deformation, confirming the design meets the operational requirements for EPU applications in the SPS-II storage ring.

Speaker: Thanapong Phimsen (Synchrotron Light Research Institute)

15:30 Design of stainless steel vacuum chambers for the HALF storage ring

The Hefei Advanced Light Facility (HALF) is positioned as an internationally advanced fourth-generation synchrotron radiation light source in the low-energy range, based on a diffraction-limited storage ring. The stainless steel vacuum chamber is a key component of HALF, with 316LN stainless steel chosen as the primary material. Its mechanical strength, corrosion resistance, low outgassing rate, and excellent process adaptability make it the ideal material for HALF.
The vacuum chamber operates in an environment subject to vibrations and radiation, necessitating high welding process requirements to prevent weld cracks and leaks. The vacuum leak rate is controlled within 2×10-11mbar.l/s. The vacuum chamber is designed to withstand baking temperatures above 250°C. After machining, the magnetic permeability of the chamber is kept at 𝜇≤1.01.For certain stainless steel vacuum chambers, the inner surface of the beam channel is coated with oxygen-free copper (TU0). This reduces the outgassing rate from the inner wall, lowers the photon-stimulated desorption coefficient, and ensures a uniform and low vacuum pressure distribution.

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

15:30 Design of the ANTHEM RFQ mechanical supports

The ANTHEM (Advanced Technologies for Human-centered Medicine) research project will establish a Research and Clinical Center in Caserta, Italy, for the study and application of Boron Neutron Capture Therapy (BNCT). The INFN (LNL, Pavia, Napoli, Torino) has in charge the design and construction of the epithermal neutron source, that will assure a flux of $10^9\ n/(s\ cm^2)$ with characteristics suited for deep tumors treatment. The Radio-Frequency Quadrupole (RFQ), designed by INFN, produces $30\ mA$ of protons at $5\ MeV$ and is composed of 3 super modules, each of which at $600\ kg$ in weight and $2.5\ m$ in length. The supports perform the iso-statical alignment during the modules assembly, coupling and alignment, and are also used to align the RFQ respect to the Nominal Beam Line, using a Laser Tracker to monitor the position with a tolerance of $0.1\ mm$. This paper details the chosen kinematic configuration, the supports design, the calculation and simulations for design validation, the procedures for regulation and alignment and the achieved results.

Speaker: Carlo Mingioni (Istituto Nazionale di Fisica Nucleare)

15:30 Design overview of the medium energy beam transport line for the ANTHEM project

The ANTHEM (Advanced Technologies for Human-centered Medicine) research project will establish a Research and Clinical Center in Caserta, Italy, for the study and application of Boron Neutron Capture Therapy (BNCT). The Radio-Frequency Quadrupole (RFQ), designed by INFN, produces proton beam of 30 mA at 5 MeV, impinging on a beryllium target. A 12 m long Medium Energy Beam Transport (MEBT) line, located after the RFQ, is responsible for transporting the beam to the target for optimal neutron production. This paper gives an overview of the design of MEBT line and details its main characteristics about beam dynamics, vacuum system and its mechanical layout.

Speaker: Edoardo Nicoletti (Istituto Nazionale di Fisica Nucleare)

15:30 Design study of distributed pumping system using NEG strips for HALF

The design study of a distributed pumping system using NEG (Non-Evaporable Getter) strips for the slender beam pipes of the Hefei Advanced Light Facility (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 chamber, which can be inserted into NEG strip and matched with magnet system, is designed. The activation temperature of NEG strip and the ultimate vacuum after activation are tested, and the results are in good agreement with those obtained from the simulation.

Speakers: Wenli Zhang (University of Science and Technology of China), Dr Baoyuan Bian (High Energy Accelerator Research Organization)

15:30 Design, fabrication, and characterization of 3D-printed photonic crystals for THz filtering applications in particle accelerator

The advancement of broadband terahertz (THz) sources has become increasingly important for various scientific and technological applications, including those in particle accelerators. To enable tunable and flexible THz source development, components capable of selective THz spectrum filtering are essential. In this work, we investigate the use of 3D-printed photonic crystal structures, specifically woodpile designs, for THz filtering applications. Using high-precision digital light processing (DLP) 3D printing, we successfully fabricate woodpile photonic crystals with high accuracy. The fabricated structures demonstrate effective spectral filtering capabilities within the THz range, offering promising potential for applications in advanced accelerator technology and related fields.

Speaker: Juna Wernsmann (Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL))

15:30 Development and laboratory validation of a precise alignment setup for electron beam-based THz radiation generation at European XFEL

We present the development and laboratory testing of a precise alignment setup for the STERN experimental area at the European XFEL, aimed at exploring beam-based THz radiation generation methods using Cherenkov waveguides. The setup employs an alignment laser to simulate the electron beam trajectory, enabling the accurate positioning of critical components, such as a copper block housing dielectric waveguides. The alignment process involves scintillator screens placed before and after the vacuum chamber to measure the electron beam trajectory, with the alignment laser subsequently adjusted to replicate this path. The experimental validation focused on the reproducibility of alignment under simulated operational conditions, testing the positioning and movement of mirrors, and ensuring the stability of the alignment system for the critical components.

Speaker: Juna Wernsmann (Deutsches Elektronen Synchrotron (DESY) and Center for Free Electron Science (CFEL))

15:30 Development of a break out box system for the 1.5GHz SRF harmonic cavity at NSRRC

This paper presents the design and implementation of a long-term operational monitoring and control module, planned for deployment after 2026 at the base of a 1.5 GHz superconducting passive harmonic cavity (SRF HC) in the TPS storage ring. The proposed system, known as the Break Out Box (BOB), consolidates multifunctional measurement and control capabilities into a compact, modular platform. Its primary objective is to optimize the signal interface of superconducting RF cavities, thereby improving system reliability, responsiveness, and maintainability.

Speaker: Fu-Tsai Chung (National Synchrotron Radiation Research Center)

15:30 Development of a new type adjustable strength permanent magnet quadrupole

An integrated concept is presented to design a permanent quadrupole magnet (PQM) using tunning modules simultaneously for varying magnetic field gradient. It is anticipated that this design will be utilized for Hefei Advanced Light Facility (HALF) in the future. This design leverages symmetry to achieve both a broad range of magnetic field gradient tunning and a narrow range of precise magnetic field gradient tunning, and produce desired high-quality quadrupole magnetic fields. The PQM primarily achieve magnetic field gradient tunning by modifying the size and position of the tunning modules. The tunning of a wide spectrum of magnetic field gradient is mainly achieved by altering the excitation direction of permanent quadrupole magnets within the tunning module. The precise manipulation of small-scale magnetic field gradient is mainly achieved by manipulating the tunning-tube to modify the excitation effect exerted by the tunning module on the central magnetic field. In light of the aforementioned principles, we propose a design for a quadrupole magnet with a magnetic field gradient approximating 70T/m and magnetic gradient tunning range attain 40% in an aperture radius of 14mm.

Speaker: Shaoxiang Dong (University of Science and Technology of China)

15:30 Development of a rotating-coil measurement system for Korea-4GSR magnets

The multipurpose synchrotron radiation accelerator (4GSR), currently under development at the pohang accelerator laboratory (PAL), offers exceptional performance with 100 times higher brilliance and an ultralow emittance of 58 pm·rad compared to third-generation synchrotron light sources. The storage ring includes 344 quadrupoles, 168 sextupoles, and 56 octupoles, most of which are designed with small half-apertures ranging from 15 to 20 mm. This paper presents the development of a rotating coil system designed to precisely measure the magnetic fields of these multipole magnets. The system employs PCB coils with a width of 12 mm as sensors, with a total coil length of 550 mm to accommodate the effective length (354 mm) of the longest quadrupole (Q51) in 4GSR. To enhance signal strength, the PCB coil was constructed with 8 layers and 64 turns. The measured signals are processed using an 18-bit high-precision integrator. The driving system consists of a step motor and an encoder with a resolution of 10,000 pulses/rev. To minimize noise in the measurement signals, a mercury slip ring with a contact resistance of less than 1 mΩ was employed.

Speaker: yoongeol Choi (Pohang University of Science and Technology)

15:30 Development of a segmented capillary for inner plasma density control and high repetition rate plasma generation in Wakefield acceleration experiments

Among the advanced approaches in Laser Wakefield Acceleration (LWFA), the use of tapered plasma density and extended acceleration lengths—demonstrated through gas jet experiments—has proven effective for generating high-energy beams. However, gas jet sources often fail to ensure stable beam quality and high repetition rates, limiting their applicability. Addressing these limitations within capillary sources could provide a more robust solution.

We propose a segmented capillary source to overcome the limitations of traditional designs. Modularized by function, this design achieves tapered plasma density through CFD-based structural optimization and enables high repetition-rate operation via a differential pumping module. Experimental results validate its effectiveness, highlighting its potential for advanced plasma acceleration applications.

Speaker: Junyeong Jeong (Ulsan National Institute of Science and Technology)

15:30 Development of an in-vacuum field measurement system for the non-linear injection kicker of the TPS storage ring

The TPS storage ring utilizes a standard four-kicker bump off-axis injection system, which is known to cause disturbances to the stored beam during injections. To address this issue, an in-vacuum non-linear kicker has been developed. This kicker features zero Bx and By fields at its center and an off-axis By, providing a potential solution to facilitate top-off injection while minimizing oscillations of the stored beam.
To evaluate and optimize its performance, an in-vacuum field measurement system is required to characterize the magnetic field distributions at various applied currents. This paper presents the mechanical design, fabrication process, and initial field measurement results of the in-vacuum field measurement system.

Speaker: Chih-Sheng Yang (National Synchrotron Radiation Research Center)

15:30 Development of residual gas analyzer measurement system capable of operating in the 10 Torr vacuum range

Residual Gas Analyzers (RGA) are widely used to mon-itor gas composition in vacuum systems. However, they are typically limited to high-vacuum environments and cannot be used directly in processes that operate at higher pressures. To solve this problem, we developed a modular and easy-to-build differential pumping system that allows an RGA to monitor vacuum environments up to 10 Torr. In this study, we present the design of this system. Thanks to its modular design, the system can be easily extended to operate at higher working pressures by adding more modules.

Speaker: Chen-Wan Hsu (National Synchrotron Radiation Research Center)

15:30 Development of robust beam window by additive manufacturing

Construction of the COMET experimental facility is underway to explore the muon-electron conversion process at the J-PARC Hadron facility. An 8 GeV proton beam supplied from the main ring irradiates a target in a superconducting capture solenoid magnet, and the produced pions and muons are transported to the experimental area. In the beam line, the muon transport solenoids are composed of superconducting magnets cooled by liquid Helium (LHe). The beam windows should be robust enough to withstand against rapid and high pressure increase in emergency of LHe quenching until rupture disks break. Simultaneously, the density of the beam window material must be low, and the thickness must be as thin as possible, while minimizing the beam energy loss for high transmission efficiency. Therefore, we have been developing a beam window built by additive manufacturing. We have successfully developed a beam window made of Ti-6Al-4V with a diameter of 269 mm, a thickness of 0.5 mm, and a proof pressure of 30 atm, and have now started development of a beam window made of AlSi10Mg.
In this presentation, we will report on the development status of the beam window by additive manufacturing.

Speaker: Shunsuke Makimura (Japan Proton Accelerator Research Complex, High Energy Accelerator Research Organization)

15:30 Enhancing bulk niobium quality: addressing surface pits and delamination in cavity manufacturing

This poster presents an overview of the efforts to resolve niobium quality issues, specifically surface pits and delamination, encountered during cavity manufacturing for the PIP-II project. Initial surface quality problems led to a temporary suspension of production. Additionally, delamination was later discovered in both formed and unformed sheets, raising concerns about the material's integrity across multiple projects. This poster will detail the challenges faced, the investigative process, and the solutions implemented to restore and enhance the quality of niobium used in cavity manufacturing.

Speaker: Anna Shabalina (Science and Technology Facilities Council)

15:30 Equivalent circuit analysis of waveguide filter

Shanghai Synchrotron Radiation Facility/Shanghai Soft X-ray FEL Facility has developed an advanced transverse deflecting structure TTDS (two-mode transverse deflecting structure), using two different rf power sources to deflect beam in any angle. Bandpass filter is a key component in the TTDS, designed to pass low-frequency signals while blocking high-frequency ones. This study uses an equivalent circuit approach to analyze the RF performance of the bandpass filter. By calculating the required S-parameters, an equivalent circuit model is derived to guide the structure and dimension design. The equivalent circuit analysis not only provides valuable insights for the design and optimization of the bandpass filter in TTDS but also offers a useful reference for the design of other waveguide filters in accelerators.

Speaker: Hanyu Gong (Shanghai Institute of Applied Physics)

15:30 Evaluation of 3D-printed plastics for ultra-high vacuum applications: outgassing and residual gas analysis

The demand for cost- and time-effective and customizable components for High Vacuum (HV) and Ultra-High Vacuum (UHV) has prompted exploration into the application of 3D-printing technology. This study investigates the viability of utilizing 3D-printed plastics in UHV by evaluating their outgassing. An extensive evaluation of 3D-printing materials was carried out, highlighting the best polymer candidates using two of the most common 3D-printing techniques, Fused Deposition Modelling and Stereolithography. Further investigations were conducted to assess the performance of select 3D-printed plastics under UHV, focusing on their low outgassing and resistance to baking temperatures. Furthermore, residual gas analysis was used to evaluate the materials compatibility with NEG coating and possible presence of other contaminants. The findings suggest that certain 3D-printed plastics exhibit promising characteristics for use in HV and UHV, with notable examples including cyclic olefin copolymer and PEEK along with Rigid 10K and Tullomer™. A comparison between machined and 3D-printed parts showed that challenges such as porosity and surface roughness are not to be a cause of great concern.

Speaker: Artur Domingues (MAX IV Laboratory)

15:30 Experimental studies of thermal contact conductance between copper, stainless steel and aluminum samples using a setup developed at ALBA Synchrotron Light Source

Accurate knowledge of the Thermal Contact Conductance (TCC) between surfaces is of great importance for the design of components in particle accelerators, such as mirrors, monochromators, filters, detectors, among others. The TCC depends on many variables such as surface finish, type of material, pressure between samples, temperature and interface materials. The TCC can be found in specialized literature, but it is not always possible to find this information for all applications. This forces the design engineer to assume conservative or optimistic values that can result in over or under sized designs. In this context, an experimental setup has been developed in the Engineering Division of ALBA to evaluate thermal contacts under ambient and cryogenics conditions, in vacuum and for different pressure ranges between samples. This work presents the latest experimental results obtained for sample combinations of Copper, Stainless Steel and Aluminium materials.

Speaker: Dr Marcos Quispe (ALBA Synchrotron (Spain))

15:30 Field measurement of permanent dipole magnet in transport line for TPS

A homemade permanent dipole magnet with Sm2Co17 is planed to replace the original electromagnet in the TPS transfer line. The prototype of 150 mm length is assembled and measured. This paper will discuss the difference between field measurement and simulation.

Speaker: Yun-Liang Chu (National Synchrotron Radiation Research Center)

15:30 Hybrid semitransparent beamstops for small-angle x-ray scattering instruments

We report a novel concept of hybrid semitransparent beamstops for small-angle xray scattering instruments, removing the need for a separate photodiode to monitor the transmitted x-ray intensity. The combination of a semitransparent aluminum core and a highly absorbing steel cover ensures minimal parasitic x-ray scattering from the beamstop itself. The modular design readily enables modification of the beamstop for different x-ray energies and fluxes.

Speaker: Jackson Luis Da Silva (MAX IV Laboratory)

15:30 Improvement of PLS-II Photon Absorbers

In synchrotron accelerators, managing the intense photon flux generated by bending magnets is very important for maintaining the accelerator's performance. The emitted synchrotron radiation, characterized by its high intensity and broad spectrum, imposes significant thermal and structural demands on accelerator components. Photon absorbers are essential to effectively block excess photons, ensuring stable operation and extending the lifespan of the vacuum components.
In this poster, I would like to introduce the new shape and analysis results to improve the performance of the vertical-type photon absorbers operating in PLS-II.

Speaker: Sangbong Lee (Pohang Accelerator Laboratory)

15:30 Industrial manufacturing of nonlinear field permanent magnets for a constant tune medical FFA

The FLASH hadron therapy accelerator proposed by Trbojevic requires permanent magnets with nonlinear fields to allow rapid cycling from 10 to 250MeV while keeping the ring tune constant. A test beamline consisting of four cells from this ring is being built at BNL to be tested at the NSRL proton facility. The magnets consist of 24 neodymium-iron-boron (NdFeB) wedges magnetised in different directions and arranged in a complex pattern to produce the desired nonlinear field profile across the oval aperture for the beam movement. Manufacturing of the two distinct types of magnets was bid for by three US companies of which one was selected. This paper details the field quality achieved across the series of magnets, with discussion of the next stage of field shimming or fine-tuning methods required to use them in an accelerator ring.

Speaker: Stephen Brooks (Brookhaven National Laboratory)

15:30 Integration of the HL-LHC machine and its services within the existing LHC tunnel: Challenges and proposed approaches for the integration of a large-scale project

The High Luminosity Large Hadron Collider (HL-LHC) project is a major upgrade of the LHC presently operating at CERN, designed to enhance the performance reach in terms of integrated luminosity collected during its operational era by another order of magnitude. It involves the replacement of the entire machine and services over more than 200 meters on each side of the high luminosity experiments of ATLAS and CMS, and other modifications across the entire LHC complex. In this context, the HL-LHC Integration team is responsible for the optimization and validation of the new machine layout to ensure an efficient installation, ease of maintenance, and effective system operation.
The paper focuses on the challenges of this integration task, in particular for gathering the information and the models to produce accurate 3D assemblies of the overall project, and identify and manage conflict resolution between different teams. This includes the coordination of several equipment groups and related design offices, adapting to spatial constraints of the existing infrastructure, managing equipment at various stages of their design, and dealing with interfaces between existing and new infrastructure.
The team employs a combination of 3D design tools and agile management strategies, such as interactive progress-tracking tools (Kanban Board), scrum, sprints and feedback loops. The integration relies on a complete 3D model from which the new reference Layout drawings and database are derived when design milestones are achieved. Integration releases through robust documentation approval and archiving systems constitute the installation baseline.

Speaker: Francesca Paola Nicoletti (European Organization for Nuclear Research)

15:30 Investigation of outgassing properties of CuZr and CuCrZr vacuum pipe

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 requirements of the HALF, the vacuum chamber structural 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 material properties and manufacturing process. In this paper, thermal outgassing performance of CuZr and CuCrZr alloy pipes under temperature rise was investigated for the design and calculation of HALF vacuum systems.

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

15:30 Investigation of properties of CuZr alloy for vacuum chamber structural materials

CuZr alloy is considered for the structural material of the vacuum chamber of the Hefei Advanced Light Facility (HALF) storage ring. We tested the outgassing rate of CuZr material. The outgassing rate of CuZr alloy can reach 4.93×10^-11 Pa·L/s·cm² after baking at 180°C for 48h, which is more than one order of magnitude lower than that of SS. These results indicate that CuZr alloy is easier to degas by baking at lower temperatures and is a material with very low outgassing rates. At the same time, it is a highly competitive structural material for future accelerator vacuum chamber based on its good electrical conductivity, high strength and hardness.

Speaker: Dr Baoyuan Bian (High Energy Accelerator Research Organization)

15:30 Key problems in the development of Lambertson magnet for HEPS booster

Three Lambertson magnets are utilized in the injection and extraction of the High Energy Photon Source (HEPS) booster. These magnets incorporate an embedded spliced core structure, integrating structural components made from FeCoV alloy (1J22) with a core composed of DT4 material. The 1J22 components are longitudinally segmented according to the core's length, with each segment processed and annealed independently before being spliced together. The regions prone to leakage magnetic fields are primarily shielded by the 1J22. Furthermore, the septum plate of the low-energy injection Lambertson magnet has a thickness of 3.75 mm, while the septum plates of the two high-energy Lambertson magnets are each 3.25 mm thick. Additionally, the uniformity of the integral main magnetic field is maintained within ±0.05%, and the integral of the leakage field is under 0.1% of the integral of the main magnetic field. The performance of the magnets all meet the specified physical requirements. In this paper, a lot of key problems in the development of magnet such as magnetic field distribution, manufacture of 1J22 components, are introduced and thoroughly discussed.

Speaker: Guanjian Wu (Chinese Academy of Sciences)

15:30 Large-area atomic layer deposition of titanium nitride for RF windows

High-power particle accelerators, like the Spallation Neutron Source, require reliable radio-frequency waveguide windows to transmit power while maintaining a vacuum. These windows face performance challenges due to multipacting, an electron cascade disrupting vacuum integrity. Thin TiN coatings can suppress this by reducing secondary electron emission, but traditional methods struggle to uniformly coat complex ceramic surfaces.
We developed an atomic layer deposition (ALD) process to create conformal TiN films (<10 nm) at low temperatures (130°C), achieving smooth, conductive coatings with a secondary electron yield below 2.0. Collaborating with Microwave Techniques LLC and Oak Ridge National Laboratory, we designed RF windows with replaceable TiN-coated ceramic disks to improve performance and reduce downtime.
In our next phase, we will scale up manufacturing and develop a modular ALD tool for in-situ coating of waveguide and SRF cavity metallic surfaces, crucial for next-generation accelerators operating at higher power. These innovations enhance efficiency, reliability, and design flexibility, advancing accelerator technology and fostering high-tech sector growth.

Speaker: Harish Bhandari (Radiation Monitoring Devices (United States))

15:30 Laser powder bed fusion for x-band RF cavities: A preliminary study

With increasing operational frequency ($f_R$), the size, weight, and power consumption of linear accelerators (Linacs) decrease, which is why e.g. X-band LinVarious studies show that additive manufacturing (AM) has the potential to significantly reduce the cost of radio frequency cavities (cavities) while increasing performance. With increasing resonance frequency, the size, weight, and power consumption of linear accelerators (Linacs) decrease, which is why, e.g. X-Band Linacs are attractive for industry, medicine, and science. This work investigates, for the first time, whether laser powder bed fusion (PBF-LB/M) offers the geometric accuracy necessary for X-Band cavity manufacturing. Eight 9.29 GHz side-coupled test cavities, each comprising three single cells, were fabricated from CuCr1Zr. One of the cavities was post-processed using plasma electrolytic polishing to increase the quality factor. The manufactured cavities were evaluated using a Vector Network Analyze and an optical 3D profiler.

Speaker: Michael Mayerhofer (Universität der Bundeswehr München)

15:30 Lifecycles and workflows for 3D integration studies at CERN

The implementation of a new product data management (PDM) and product lifecycle management (PLM) system at CERN has significantly improved lifecycles and workflows for 3D integration studies, thanks to the advanced features and tools of the platform. This new PDM/PLM system has provided an opportunity to reassess and optimize user methodologies, focusing on better organization of 3D CAD data, improved collaboration with mechanical and services design offices, and more effective validation processes. Additionally, enhanced traceability throughout workflows is expected to boost overall process quality. This paper examines the challenges encountered during the transition as well as the benefits of the new PDM/PLM, highlighting its contribution to increased efficiency and quality.

Speaker: Daniel del Alamo (European Organization for Nuclear Research)

15:30 Magnetohydrodynamic effects in liquid lead target concept for Muon Colliders

The use of liquid lead as a target material in particle accelerators is of significant interest due to its high density, high thermal power absorption capacity, and resistance to radiation damage. This makes it particularly well-suited for the high-intensity proton beams being studied for CERN’s Muon Collider proposal, with powers ranging up to 4 MW. To minimize shock propagation and manage the intense thermal and mechanical stresses induced by the high-power proton beam, a free-falling liquid lead curtain is explored as a promising concept. However, the target region requires strong magnetic fields, around 20 T, to re-focus the secondary particles generated at the target, introducing complex magnetohydrodynamic (MHD) effects in the liquid metal flow. These effects, particularly caused by Lorentz forces and MHD losses, present challenges to achieving stable and efficient high-power target systems. This work presents multiphase MHD simulations that reveal flow instabilities and highlight potential concerns within the free-falling curtain concept. The findings provide critical insights into the feasibility of liquid lead targets for high-intensity beams.

Speaker: Silvio Candido (European Organization for Nuclear Research)

15:30 Material properies of 3D-printed copper for rf-cavities

This study investigates the material properties of 3D-printed copper for use in radio frequency (RF) cavities, with a focus on its suitability for high-performance accelerator applications. Key aspects include an analysis of the corrosion and erosion resistance of the printed copper, as well as its electrical and thermal conductivity. Results demonstrate the potential of additive manufacturing for producing RF components while addressing challenges related to material performance under operational conditions. The findings contribute to the development of advanced manufacturing techniques for efficient and durable RF cavity fabrication.

Speaker: Klaus Kümpel (Goethe University Frankfurt)

15:30 Mechanical design and challenges of the FCCee arc radiation shielding

The FCC-ee faces challenges in managing radiation from primary synchrotron photons, which can damage machine components and tunnel equipment due to cumulative exposure. Effective shielding is crucial to reduce equipment failure, prevent performance degradation, and limit reliance on costly radiation-hard materials.

The proposed solution involves enclosing photon stoppers with shielding inserts and plates. With 2580 dipoles, each containing 10 photon stoppers, the machine requires shielding for 25800 stoppers. A preliminary lead-based design shows promise in dose reduction, but optimization is needed to control costs, meet integration constraints, and ensure manufacturing feasibility. Current estimates suggest each stopper will require 400 kg of shielding, totaling 10320 tons of lead. Optimization focuses on refining the shielding’s shape, size, and materials, while simplifying fabrication and installation to improve scalability. Goals include detailed cost estimates, spatial assessments, and a design addressing thermal management, mechanical integrity, and structural support, ensuring significant reduction of ionizing dose. This work is vital for proving the FCC’s feasibility.

Speaker: Alvaro Romero Francia (European Organization for Nuclear Research)

15:30 Mechanical displacement of the prototype chamber for the Korea-4GSR

The Korea-4GSR storage ring vacuum chamber is composed of materials such as aluminum and stainless steel. Among these, the aluminum extruded chamber for Pill getter insertion undergoes in-situ bake-out and getter activation in the storage ring tunnel at a temperature of 180°C for over 24 hours. The gap between the electromagnet and the vacuum chamber is as narrow as 1–2 mm, which could lead to physical interference between the magnet and the chamber due to thermal expansion caused by the bake-out process. Therefore, the displacement of the aluminum vacuum chamber due to temperature increase has been calculated and measured based on the position and type of supports. This presentation aims to discuss the optimization of the bellows and support designs for the aluminum vacuum chamber.

Speaker: Jaehoon Kim (Pohang Accelerator Laboratory)

15:30 MEDSI 2025: Celebrating 25 years of innovation in synchrotron engineering

The 13th International Conference on Mechanical Engineering Design of Synchrotron Radiation Equipment and Instrumentation (MEDSI 2025) marks the 25th anniversary since the first MEDSI workshop in 2000. This biennial meeting, hosted by MAX IV Laboratory in Lund, Sweden, from September 15–19, 2025, is expected to welcome over 300 delegates and more than 30 industrial exhibitors. MEDSI is the leading forum for advancing engineering in synchrotron and free-electron laser (XFEL) facilities, featuring sessions on precision mechanics, photon delivery, simulation, and core technology developments. MEDSI 2025 will also introduce a special session on neutron source instrumentation, emphasizing collaboration with the European Spallation Source (ESS). The event includes invited and contributed talks, poster sessions, and an industrial exhibition, with all contributions published in the JACoW Proceedings. For more information, visit www.medsi2025.com.

Speaker: Staffan Benedictsson (MAX IV Laboratory)

15:30 Network system upgrade and information security management system implementation at NSRRC

With the advancement of science and technology, people are more dependent on the Internet and digital technology. We continue to improve our network system to increase speed and security of information transmission at NSRRC. We had established various levels of Information Security System (ISMS) documents and conducted many tasks and obtained the certification of ISO-27001.

Speaker: Jui-Chi Chang (National Synchrotron Radiation Research Center)

15:30 New analysis tools for LHC aperture measurements

Aperture measurements at the Large Hadron Collider (LHC) are routine procedures conducted during the early stages of beam commissioning, prior to the injection of high-intensity beams. This is to ensure that the aperture, defining the clearance for the circulating beams, is protected by the LHC collimation system. Local aperture measurements are performed to probe the available aperture at specific locations. Such measurements are carried out by applying a local orbit bump in the area of interest. The bump amplitude is increased until the beam touches the aperture, visible through signals in the local Beam Loss Monitors. This contribution introduces a refined approach to analyse local aperture measurements by incorporating measured beam position monitor (BPM) signals to enhance the precision of the analysis. Using the Xsuite package, the orbit bump is simulated and rematched to the measured BPM signal to enhance the analysis and quantify the uncertainties with respect to the theoretical beam orbit. Using past measurement data, we compare the results obtained using the established and revised methodologies and conclude on derived measurement uncertainties.

Speaker: Roderik Bruce (European Organization for Nuclear Research)

15:30 Non-destructive & destructive testing on accelerator’s components and materials at the European Spallation Source

The European Spallation Source - ESS, has achieved its major construction in Lund, Sweden and is currently continuing in parallel the commissioning of its first systems. ESS aims to install and commission the most powerful proton LINear ACcelerator (LINAC) designed for neutron production and a 5MW Target system for the production of pulsed neutrons from spallation. In support of this ambitious goal, the Mechanical Measurements Lab (MML) at ESS provides an array of investigative solutions such as Resonant Ultrasound Spectroscopy (RUS), Transient Grating Spectroscopy (TGS), Modal Analysis, Structural Health Monitoring (SHM), Strain and Stress Analysis and Destructive Testing, guaranteeing full support to all the groups that have the mandate to install all the different components of the machine. The scope of this contribution is to describe the current status of the undergoing studies, together with the applied methodology and the definition of the testing apparatuses.

Speaker: Andrea Bignami (European Spallation Source)

15:30 Novel photoinjector laser providing advanced pulse shaping for FLASH and EuXFEL

We recently commissioned the Next GenerAtion Photocathode Laser system (NEPAL) in Hamburg’s XFEL facilities (FLASH and EuXFEL) and at DESY’s Photoinjector Test Facility (PITZ). The system delivers deep UV pulse trains up to 1 ms long at repetition rates as high as 4.5 MHz, with temporal and spatial shaping capabilities and individual amplitude control for bunch charge manipulation. The shaping features enable the generation of exceptionally low emittance electron beams, essential for extending the EuXFEL X-ray photon energy beyond 25 keV and for future high duty cycle upgrades. Temporal shaping is achieved through a high-resolution spatial light modulator in the near-infrared driver laser, allowing precise spectral amplitude and phase control of UV pulses. We will present advanced control schemes that pre-compensate for laser nonlinearities and initial experimental results at EuXFEL. We generated UV flat-top pulse profiles with durations ranging from 10ps to 20ps and successfully transferred them onto the electron beam. This achievement represents a significant step toward emittance optimization at EuXFEL and will expand the facility's operational energy range in the near future.

Speaker: Denis Ilia (Deutsches Elektronen-Synchrotron DESY)

15:30 Numerical simulation of a modified air conditioning system of the experimental hall at TPS

Taiwan Photon Source (TPS) has been committed to serve users for eight years. In the first and second phases of TPS beamline project, there were 16 beamlines had been in operation. The third phase project had been launched in 2021. Facing the more persons and equip-ment in the experimental hall as well as power saving issue, we applied the computational fluid dynamic (CFD) scheme to simulate the air conditioning system to obtain better cooling efficiency. We modelled one twelfth of the TPS experimental hall and two beamlines.

Speaker: Jui-Chi Chang (National Synchrotron Radiation Research Center)

15:30 Overview of IFMIF-DONES lithium target system design

At the core of IFMIF-DONES is placed the Target System. It generates a high-speed liquid lithium jet (15 m/s, 300°C) acting as the target for a 40 MeV, 125 mA deuterium-based linear accelerator, with the primary aim of qualifying fusion-related materials. The design of the Target System has evolved during the last few years addressing key challenges. Managing the 5 MW of power deposited continuously in the target requires a reliable lithium loop supplying liquid lithium in well-defined conditions. The extreme operational conditions, exposed to high irradiation levels (~25 dpa/year), demand also careful selection of materials and regular replacement strategies for critical components, supported by dedicated Remote Handling systems. Current efforts focus on optimizing the design to meet the requirements for its upcoming construction phase. This includes advanced features to facilitate assembly, installation, and long-term operability. Additionally, attention is being paid to the integration of diagnostics. This contribution highlights the recent R&D and engineering solutions aimed at advancing the Target System toward successful construction, commissioning and subsequent operation.

Speaker: Jorge Maestre (Consorcio IFMIF-DONES España)

15:30 Performance evaluation of additively manufactured pure copper radio frequency quadrupole by low-power RF and high-field gradient tests

This paper presents studies on advanced accelerator technologies conducted under the I.FAST (Innovation Fostering in Accelerator Science and Technology) EU project, focusing on additive manufacturing (AM) advancements. AM, particularly powder bed fusion, is giving unique production capabilities for accelerator components. As a proof-of-principle, a full-size pure copper Radio Frequency Quadrupole (RFQ) was successfully manufactured earlier. Low-power RF tests and bead-pull measurements performed on this prototype confirmed the precise electromagnetic field distribution, validating design accuracy and repeatability. Furthermore, high-field gradient tests conducted in the CERN's DC pulsed measurement system showed that AM copper electrodes spaced of 94 µm can achieve gradients up to 42 MV/m. These promising results highlight the transformative potential of additive manufacturing in producing high-frequency accelerator components, advancing both precision and reliability.

Speaker: Prof. Toms Torims (European Organization for Nuclear Research)

15:30 Permanent magnet-based dipole-quadrupole magnet for SPring-8-II

In recent years, permanent magnet (PM) based multi-pole magnets have become an increasing concern as a replacement for conventional electro-magnets for light sources. The PMs are possible to save both energy and costs for operating and construction the facilities due to the absence of a power supply and cooling system. They have other advantages such as less space without magnetic coils and fewer failures than the conventional electro-magnets. PMs have specific issues, such as the adjustability of the magnetic field, demagnetization, and temperature dependence. Solutions to these issues were already confirmed with dipole structures for SPring-8-II, a major upgrade project of SPring-8 to the fourth generation. We have extended the knowledge and schemes to a dipole-quadrupole combined-function magnet (DQM) that comes in a quadrupole structure. The DQM is readily splittable into an upper and lower half for installation of a vacuum chamber. The reproducibility of the field gradient with half-splitting was less than 0.1%, which is within the required value. We report on the design and trial-manufacture of the PM based DQM.

Speaker: Shin-ichi Matsubara (Japan Synchrotron Radiation Research Institute)

15:30 PM magnet development status for BESSYII+

Permanent-Magnet (PM) magnets combine up to zero power consumption with highly stable magnet operation without ripple and cooling vibration effects for more energy-efficient and stable accelerator operation.
As part of the upgrade program BESSYII+, we will install the B2PT dipole triplet as the first PM-based accelerator magnet. It concludes the BESSYII transfer line, transporting the electron beam from the booster to the storage ring and bends the beam into the injection septum of the BESSYII storage ring.
The new B2PT is planned with three PM hybrid dipole units of 300 mm length each to substitute the present power-hungry 1-m long electromagnet. The triplet produces a stable magnetic field that can be trimmed during operation by electro-correctors in the outer magnets. The permanent magnetic field reduces injection noise into the storage ring and shrinks the total power consumption by almost 30 kW.
This paper reviews simulated beam bending optimization of the B2PT PM triplet and its assembly process opening up to PM magnet development also required for the preparation of the future 4th-gen low-emittance source BESSYIII.

Speaker: Ilia Asparuhov (Helmholtz-Zentrum Berlin für Materialien und Energie)

15:30 Preliminary design of the magnet girder for the HALF storage ring

Hefei Advanced Light Facility (HALF) was the fourth generation diffraction limited storage ring light source under pre-research in National Synchrotron Radiation Laboratory (NSRL) of China. Beam position stability was strictly required with the ultra-low beam emittance. The beam position stability of storage ring was affected by many factors. And the changes of magnetic field center position and magnetic field shape were the main factors. Because the magnets were installed on the mechanical support, therefore the alignment adjustment accuracy of magnet installation and the stability requirements of long-term magnetic field put forward new challenges to the design of magnet girder.
Based on the requirements of magnet support adjustment accuracy and stability, this paper designed the magnet girder and introduced the development progress of the girder. The adjustment performance test of magnet girder showed that the accuracy was better than 10 μm，the resolution was 1 μ m，and the first natural frequency in magnets scondition was 60Hz.

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

15:30 Pumping properties of Pd/Ti non-evaporable getter film

Non-evaporable getter (NEG) films are ideal for maintaining ultra-high vacuum (UHV) conditions in particle accelerators, owing to their uniform pumping speeds and negligible outgassing characteristics. However, the requirement for thermal activation limits the applicability of NEG films. Prolonged exposure to atmospheric conditions and repeated activation cycles lead to a gradual increase in their activation temperature. This poses significant challenges for accelerator maintenance. The Pd/Ti composite film, created by depositing a palladium (Pd) layer onto a titanium (Ti) film, enhances oxidation resistance and reduces activation temperatures. In this study, a double-layer Pd/Ti film was deposited onto oxygen-free copper (OFC) samples, and a specialized device for measuring its pumping speed was designed and constructed. Additionally, the microstructures, cross-sectional elemental distributions, surface elemental compositions, and pumping properties of the films were tested and analyzed.

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

15:30 Quality and performance measurement of glued Samarium-Cobalt magnet blocks

The Samarium-Cobalt (Sm₂Co₁₇) permanent magnet block is a promising material for accelerator applications due to its high radiation resistance, low temperature coefficient, high coercive force, and rust resistance. However, Sm₂Co₁₇ is costly and easily to brittleness. To reduce production costs, a glued Sm₂Co₁₇ block has been developed as a substitute for large blocks, which helps to lower equipment expenses for Sm₂Co₁₇ production. The National Synchrotron Radiation Research Center (NSRRC) has developed and implemented glued Sm₂Co₁₇ blocks in soft-iron pole magnets. This report discusses various applications of glued Sm₂Co₁₇ blocks and evaluates their quality.

Speaker: Chi-Chuan Tsai (National Synchrotron Radiation Research Center)

15:30 Recent progress at the Low Energy Accelerator Development Facility

The Low Energy Accelerator Development Facility * is located at the site of the Brookhaven National Laboratory (Upton, NY, USA) and is aimed to run a program specially targeting new collaborations for user-driven research. The facility has two fully radiation-shielded bunkers (153 and 77 sq. m) to where a range of electrical, cooling and RF capabilities are presently being introduced. The facility runs also the Ultrafast Electron Diffraction (UED) Facility.
The first shielded bunker will support the deployment of a demonstrator for the Electron Cyclotron Resonance Accelerator ** (eCRA). The deployment is expected to start in April of 2025. At the UED Facility beamline updates are now going into place for a NASA Jet Propulsion Laboratory *** electron irradiator beamline for Single Event Effects (SEE) testing; the capability for UED/UEM testing will be expanded; and the deployment of a new stable solid-state modulator and klystron is in progress.
The presented article provides further details.

Speaker: Mikhail Polyanskiy (Brookhaven National Laboratory)

15:30 Research of resonant kicker for CEPC RF region beam separating system

In the CEPC TDR, the RF beam separating system adopts an electro-magnetic separator scheme. The adverse issues of DC HV as high as hundred kV and beam impedance of the electrostatic separator are inevitable, so an alternative solution using kicker magnets and septum magnets was proposed. Compared with static-electrical separator, kicker magnet is stronger and contributes lower beam impedance. According to specific physical parameters, the integral field strength of the kicker magnet is 0.1624 T·m, the magnetic field strength is 203 Gs, the effective length of the magnet is 8 m, the half-width of beam stay clear is 10.1×3.8 mm (H×V), and the half-width of good field region is 9.6×3.6 mm (H×V). Based on this, the resonant kicker research was conducted.

Speaker: Guanjian Wu (Chinese Academy of Sciences)

15:30 Sputtering characteristics of a compact NEG-coating device and performance evaluation of the TiZrV thin films

Non-evaporable Getter (NEG) coating is a breakthrough technology wherein the inner walls of a vacuum chamber are coated with a material that functions as a vacuum pump. This technology is expected to gain widespread adoption across various fields in the future. However, the current coating method, originally developed for long beam ducts, is not adaptable to a wide range of vacuum chamber designs. Therefore, we have developed a compact NEG coating device that can be adapted to chambers of various geometries. The primary advantage of this device is its ability to coat complex-shaped chambers, which was difficult with conventional methods. Additionally, by reducing the uncoated surfaces as much as possible, it significantly improves pumping performance in terms of pumping speed and reducing Photon Stimulated Desorption (PSD) yields. We explore the optimal sputtering conditions for depositing high-performance NEG thin films with the device, and have performance evaluations of the NEG films, with observing the morphologies, measuring the pumping speed and PSD yields.

Speaker: Ruau Watanabe (The Graduate University for Advanced Studies, SOKENDAI)

15:30 Status of the low-Z SPS slow extraction electrostatic septum development

The impact of high-flux protons on beam loss during slow extraction from the SPS to the North Area has been discussed, and improvements have been proposed focusing on reducing activation, lifetime reduction, and anode body distortion. The conducted studies shall demonstrate the feasibility of replacing the stainless-steel tank, flanges, and anode body with low-Z materials. A reduced-length prototype was fabricated to demonstrate mechanical, electrical, and vacuum performance. The paper presents the vacuum vessel development from the reduced-length prototype to the full-length setup, including numerical analysis.
Prototype qualification tests, including vacuum performance, leak-tightness, high-voltage feedthrough performance, and deformation during evacuation, will be discussed to confirm that the tank remains within predicted non-linear buckling limits.

Speaker: Laurent Ducimetière (European Organization for Nuclear Research)

15:30 Study of a girder system for the Korea-4th Generation Synchrotron Radiation (4GSR) accelerator

The Korea 4th-Generation Synchrotron Radiation (4GSR) accelerator requires exceptionally high mechanical stability to ensure reliable beam operation with an extremely small beam size. To achieve this, a robust grid-er system is essential for supporting accelerator components such as magnets, vacuum chambers, and beam position monitors (BPMs). The girder system must suppress vibrations originating from the ground to prevent disturbances in the electron beam trajectory, while also maintaining sufficient mechanical rigidity to support heavy components like electromagnets. In the Korea 4GSR project, the girder system is required to maintain a misalignment tolerance within ±100 μm and limit vibration amplitudes to less than 10% of the beam size to ensure beam stability. However, with a storage ring circumference of approximately 800 meters, meeting these specifications poses significant challenges. This study presents the development of a girder system using finite element analysis (FEA) methods to achieve both mechanical stiffness and adjustability, thereby ensuring the required beam stability.

Speaker: Gwang Wook Hong (Pohang Accelerator Laboratory)

15:30 Study on the feasibility of incorporating ozonized water into the ultra-high vacuum chemical cleaning process for aluminum vacuum chambers

The feasibility of incorporating ozonized water into the ultra-high vacuum (UHV) chemical cleaning process for aluminum vacuum chambers was investigated. The experiments were conducted using custom-designed wet bench equipment under various temperature and time conditions. Auger analysis was used to evaluate the removal of organic contaminants, and TEM analysis measured changes in oxide layer thickness. Subsequently, similar experiments were conducted on a prototype 4GSR vacuum chamber, and vacuum quality was assessed through outgassing rate measurements and RGA analysis. Based on these results, we quantitatively and qualitatively determined the optimal reaction time, temperature, and process sequence for ozonized water treatment in UHV chemical cleaning. This method is expected to more effectively remove initial chemical impurities and physical contaminants from the surface or interior of aluminum materials under specific conditions. Consequently, it may help reduce photon-stimulated desorption rates, contributing to a shorter conditioning time in the 4GSR project and ultimately enabling the achievement of higher vacuum levels.

Speaker: Jin Gyu Kim (Pohang Accelerator Laboratory)

15:30 Surface characterization of vacuum chambers with synchrotron radiation exposure at a beamline

Exposure of synchrotron radiation on the vacuum chambers induces high yield of photoelectrons and the consequent increase of pressure from stimulated gas desorption. Characterization of the surface quality of vacuum chambers, either after chemical cleaning or with thin film coating, by synchrotron radiation exposure at a beamline is powerful and sensitive. In this study, analysis of photo-desorption and photoelectron yield for various vacuum chambers, metallic tubes with or without NEG-coatings, at the BL19B-beamline of Taiwan Light Source (TLS) with critical photon energy of 2.14 keV will be described and compared.

Speaker: Gao-Yu Hsiung (National Synchrotron Radiation Research Center)

15:30 Survey and alignment of the MESA accelerator

The Mainz Energy recovery Superconduction Accelerator (MESA) will be a recirculating electron linear accelerator, capable of delivering beam energies up to 155 MeV and 150 µA in external beam mode or 105 MeV and 10 mA in energy recovery mode. The building consists of a tunnel for the electron guns, spin preparation, and normal conducting pre-accelerator up to 5 MeV and 10 mA. The main accelerator is setup in the neighboring four underground experimental halls.
The process of a survey of the building structures, establishing a network of reference points and a common coordinate system is presented. Furthermore the different methods, for example a classic approach with theodolites aligned on the accelerator axis for alignment in the tunnel, but also the use of a total station and a modern laser tracker for building survey and alignment of the main accelerator components will be discussed. Finally, an overview of achieved uncertainties and systematic errors will be given.

Speaker: Juergen Diefenbach (Institut für Kernphysik)

15:30 The vacuum system design of the RF cavity section in the booster of the Iranian Light Source Facility

The Iranian Light Source Facility (ILSF) Booster, which is currently in the design phase, has a circumference of 504 meters and accelerates electron bunches from 150 MeV to 3 GeV. The RF cavity section of the Booster is a key area, where maintaining ultra-high vacuum (UHV) conditions is essential to ensure stable beam acceleration and minimize beam-gas interactions. This work presents the integrated layout of the vacuum system for the RF cavity section of the Iranian Light Source Facility Booster. The conceptual design of the RF cavity section for the ILSF Booster, developed to meet these requirements, consists of three 100 MHz main cavities. The pressure profile has been calculated using Monte Carlo simulations, and the results fall within the accepted operational limits of the machine. These results suggest that three diode ion pumps, each with a pumping speed of 300 l/s, will be required to attain the desired pressure in the ultra-high vacuum regime.

Speaker: Saeedeh afhami (Iranian Light Source Facility)

15:30 The vacuum system design of the RF cavity section in the storage ring of the Iranian Light Source Facility

The Iranian Light Source Facility (ILSF) is a 3 GeV synchrotron light source designed to serve as a cutting-edge tool for scientific research, providing high-brightness X-rays for a wide range of applications. In the booster ring, particles are accelerated to a final energy of 3 GeV and then stored in a storage ring with a maximum beam current of 400 mA.
The RF cavity is a fundamental component of synchrotron light sources, playing a critical role in ensuring optimal machine performance. Optimizing the operational characteristics of the RF cavity significantly enhances the quality of the emitted radiation. The conceptual design of the RF cavity system of storage ring for ILSF to meet these requirements consisting of three 100 MHz main cavities plus two 300 MHz for bunch lengthening. A Monte Carlo simulation was conducted using Molflow and Synrad to calculate the pressure profile along the RF cavity straight of the ILSF. The results indicate that three diode ion pumps, each with a pumping speed of 300 l/s for 100 MHz, and two diode ion pumps, each with a pumping speed of 75 l/s for 300 MHz, will be necessary to achieve the desired pressure in the ultra-high vacuum regime.

Speaker: Saeedeh afhami (Iranian Light Source Facility)

15:30 The wire alignment method in a magnetic field measurement system

In the magnetic field measurement system, a single-core CuZr wire is used in both the stretched-wire (SW) and pulsed wire measurement (PWM) systems. Before measuring the magnetic field of the undulators, the CuZr wire must be aligned with the center of the undulator mechanism. The SW system is then employed to locate the magnetic field center of the undulator. The traditional method involves using a theodolite and level to align the CuZr wire with the center of the undulator mechanism. However, for cryogenic permanent magnet undulators (CPMUs), superconducting magnets, or any magnets installed in a vacuum chamber, aligning the CuZr wire with the center of the mechanism using traditional methods presents challenges. In this paper, we propose a method that utilizes the wire's contact with the magnet to observe changes in resistance for positioning purposes, thereby overcoming the limitations of center alignment in chamber-surrounded undulator mechanisms.

Speaker: Hsiung Chen (National Synchrotron Radiation Research Center)

15:30 Thermal-structural analysis of the Korea-4GSR vacuum chambers

The Korea-4GSR is a fourth-generation synchrotron radiation accelerator with an energy of 4 GeV, a beam current of 400 mA, and a circumference of 800 m. To satisfy the performance requirements of the storage ring, the gap between the electromagnets and the vacuum chamber is designed to be extremely narrow, from 1.5 mm to 2 mmA portion of the synchrotron radiation generated in the storage ring is delivered to the beamlines, with most absorbed within the storage ring using various types of photon absorbers installed throughout the system, while some photons are directly absorbed by the vacuum chamber. To prevent interference caused by thermal deformation of the vacuum chamber during this process, stress, deformation, and temperature distributions due to synchrotron radiation were analyzed using Ansys.
This study proposes optimization strategies to ensure the mechanical stability of the vacuum chamber under synchrotron radiation exposure.

Speaker: Hosun Choi (Pohang Accelerator Laboratory)

15:30 Transient Grating Spectroscopy for accelerator applications at the European Spallation Source

The European Spallation Source ESS is a multi-nation, interdisciplinary research facility based on the world’s most powerful neutron source that will operate with high standards of availability and reliability minimizing downtime periods. In order to meet these goals, critical component’s performance and aging need to be constantly monitored and assessed. Transient Grating Spectroscopy (TGS), a laser-based tecnique developed for the study of nuclear materials, has been established at ESS as an investigating tool for comparing values of thermal diffusivity before and after irradiation in particle accelerators’s materials. The implementation of this non-destructive method offers a powerful instrument for assessing the characteristics of the materials during the design phase of current and future components and, with further development in terms of resizing and deployability, also opens up the possibility for its application in the online monitoring of the machine.

Speaker: Andrea Bignami (European Spallation Source)

15:30 Upgrading the IMPACT application for enhanced risk declaration and approval processes at CERN

The declaration and approval of activities related to CERN's accelerator complex are critical for ensuring safety and compliance. For the past 12 years, the Intervention Management Planning And Coordination Tool (IMPACT) has been the primary system facilitating these processes, enabling approvals by domain and location experts. However, evolving requirements and advancements in technology have necessitated a significant upgrade.

This paper introduces the new system, which represents a migration from the legacy IMPACT application. It preserves historical data while offering key improvements in usability, especially for mobile platforms. The updated system simplifies user interactions with clearer workflows and interfaces, reducing complexity for those declaring or approving activities.

The development process prioritized a user-centric approach, incorporating iterative testing with stakeholders to ensure the system meets the operational needs of CERN's diverse activities. This paper outlines the technical architecture of the new system, strategies for data migration, and mechanisms designed to improve safety communication. This initiative aligns IMPACT with the integrated engineering platform developed by the Engineering department and contributes to CERN’s overarching goal of advancing safety standards through robust digital solutions.

Speaker: Giovanni Chierico (European Organization for Nuclear Research)

15:30 Utility design of the 3 GeV electron storage ring for Siam Photon Source II

The Siam Photon Source II (SPS-II) is a new synchrotron light source currently under development in Thailand. Its 3 GeV electron storage ring features a lattice composed of 14 Double Triple Bend Achromat (DTBA) cells, with a total circumference of 327.6 meters. To ensure beam stability and operational reliability, a comprehensive suite of utility systems is required. The design incorporates critical infrastructure, including the electrical power system, deionized (DI) water system, air conditioning system, and compressed air system. These utilities provide essential support to both accelerator and beamline subsystems, such as magnets and power supplies, RF cavities and power supplies, vacuum chambers, insertion devices, front-end components, and experimental beamlines. This paper focuses on design considerations for the stability of the electrical power systems and the temperature regulation of the DI water and air conditioning systems. The electrical power demands and cooling loads are estimated based on the specific operational requirements of each accelerator subsystem.

Speaker: Supachai Prawanta (Synchrotron Light Research Institute)

15:30 Utilization of renewable energies for sustainable accelerator operation at KIT

The Karlsruhe Institute of Technology operates the accelerator test facility Karlsruhe Research Accelerator, which also provides synchrotron radiation at 2.5 GeV. Roughly one third of the wall-plug power is used for cooling. Optimizing the infrastructure for cooling has a huge impact on the overall sustainability. To reduce the environmental impact a thermal well system was installed. It reduces the base heat load by eliminating one of three 500 kW cooling units. This paper describes the challenges, such as iron-manganese rich groundwater, and their solution for our 1 MW passive cooling system. The average energy consumption of 28 kW for the thermal well infrastructure is compensated by a new 540 kWp solar power plant. This paper elaborates on the commissioning of the wells and shows the first results of this overall sustainable cooling concept.

Speaker: Julian Gethmann (Karlsruhe Institute of Technology)

15:30 Vacuum performance analysis of low-temperature activated getter pump with different sintering conditions

The pumping speed of pill-type getter pumps for low-temperature activation, fabricated under different sintering conditions, were measured at various temperatures. To reduce uncertainty, the pumping speed measurements were performed on more than 70 getter pumps. This measurement method has limitations: it measures the pumping speed only on one side of the getter and may overestimate the speed due to the influence of getter powder. Therefore, the pumping speed of a single pill-type getter pump was measured and compared in accordance with ASTM F798-97.

Speaker: Sehyun Kim (Pohang Accelerator Laboratory)

15:30 Vacuum system of MAX4U – an upgrade of MAX IV 3 GeV storage ring

MAX 4U is an upgrade project of the MAX IV 3 GeV storage ring, to be realized by the early 2030’s in Lund, Sweden. The goal of the upgrade is to reduce the horizontal electron beam emittance to below 100 pm.rad. A new magnet lattice will be used, thus the vacuum system will have to be adapted to follow the new beam orbit of MAX 4U.

Several lattices imposing the most severe changes to the beam orbit were studied. One proposal for the MAX 4U vacuum system is to re-use and adapt under vacuum the shape of the MAX IV 3 GeV ring vacuum chambers (coated with non-evaporable getter (NEG) thin film) by bending-to fit to the new magnet lattice. In such scenario, the vacuum system will not be vented, thus the NEG coating will not have to be re-activated. Such approach is very cost-effective and reduces the installation and commissioning time to the minimum. This scenario is presented here, together with the performed simulations, validation studies and tests.

Speaker: Mr Marek Grabski (MAX IV Laboratory)

17:10 Power quality measurement and analysis for grid-connected rooftop photovoltaic systems at NSRRC

NSRRC started its solar energy systems installation project in 2016 and began construction in early 2017. Solar modules have been gradually planned and installed on the rooftops of office, laboratory, and Utility buildings. The total installed capacity has now accumulated nearly 1.2MWp, and the total electricity generated to date has reached 10.8GWh, with a total carbon reduction of 5.7kt. This article will analyze and discuss various monitoring data (including voltage/current imbalance rate, harmonic distortion, active power, power factor, etc.) measured during the operation of the solar energy generation system in parallel with the power grid.

Speaker: Yung-Feng Chiu (National Synchrotron Radiation Research Center)

15:30 → 17:30 Thursday Poster Session: THPM

Thursday Poster Session

15:30 A Bayesian multi-objective framework for optimizing an electron injector linac

This study introduces a multi-objective Bayesian optimization framework to enhance the performance of electron linear accelerators in Fourth Generation Synchrotron Radiation facilities. By focusing on minimizing horizontal and vertical emittances and energy spread at the linac exit, the approach targets improved beam quality essential for advanced synchrotron applications. Traditional methods face challenges balancing these competing objectives due to system complexity and nonlinearity. Bayesian optimization addresses this by combining probabilistic modeling and sequential sampling to efficiently navigate the high-dimensional parameter space, balancing exploration and exploitation while iteratively refining predictions. Results demonstrate the framework's ability to reduce emittances and energy spread effectively and efficiently. This scalable, adaptive method offers a robust optimization strategy for improving performance across accelerator systems in multi-objectives

Speaker: Chong Shik Park (Korea University Sejong Campus)

15:30 A full digital beam position and phase measurement signal processing algorithm based on FPGA designed for linear accelerator

A new digital beam position and phase measurement (BPM) system was designed for the ion-Linac (iLinac) accelerator in the High Intensity heavy ion Accelerator Facility (HIAF). The fundamental and the second harmonic signals are retrieved from the BPM electrodes to simultaneously calculate their respective beam positions and phases. All data acquisition and digital signal processing algorithm routines are performed in a field programmable gate array (FPGA). The position and phase information are obtained by using the in-phase and quadrature (IQ) demodulation method. A practical and straightforward method is used to generate the second harmonic reference signal for processing the second harmonics beam signal. The reconfigurable filters are integrated into the FPGA to allow the measurement of short beam pulse length. The laboratory test results show the achieved phase resolution is better than 0.2$^{\circ}$ and 0.03$^{\circ}$ when the input signal is -60 dBm and -45 dBm respectively. A position resolution better than 30 $\mu$m was achieved for an input power level of approximately -60 dBm, and it can reach 7 $\mu$m with the input power higher than -45 dBm. The entire execution time of the algorithm is accomplished within 3.4 $\mu$s, which provides a sufficient reaction time for the fast beam interlock signal to the machine protection system (MPS). The performance of this newly designed prototype BPM electronics was evaluated with the online proton beam.

Speaker: Fafu Ni (Institute of Modern Physics, Chinese Academy of Sciences)

15:30 A non-destructive weak beam current measurement electronics for HIRFL

Non-destructive measurement of low-intensity charged particle beams poses significant challenges in beam diagnostics. At the Heavy Ion Accelerator Facility in Lanzhou (HIRFL), beams with currents below 1 μA are frequently used in experiments, which fall below the detection threshold of standard beam current transformers. To address this, a low-intensity monitoring system was developed, utilizing a sensitive capacitive pick-up (PU) and low-noise electronics. This system measures beam currents by digitally analyzing PU signal amplitudes using a homodyne detection scheme. Laboratory tests showed an amplitude nonlinearity of <0.5% within the operational range of 1 nA–45 μA and an amplitude resolution of 0.94 nA. Currently, four such systems are installed at HIRFL for monitoring low beam currents below 1 μA. Following absolute calibration with a Faraday cup, the system achieves accurate beam intensity measurements with a resolution of approximately 1 nA.

Speaker: Yuan Wei (Institute of Modern Physics, Chinese Academy of Sciences)

15:30 Application of large language models for the extraction of information from particle accelerator technical documentation

The large set of technical documentation of legacy accelerator systems, coupled with the retirement of experienced personnel, underscores the urgent need for efficient methods to preserve and transfer specialized knowledge. This paper explores the application of large language models (LLMs), to automate and enhance the extraction of information from particle accelerator technical documents. By exploiting LLMs, we aim to address the challenges of knowledge retention, enabling the retrieval of domain expertise embedded in legacy documentation.
We present initial results of adapting LLMs to this specialized domain. Our evaluation demonstrates the effectiveness of LLMs in extracting, summarizing, and organizing knowledge, significantly reducing the risk of losing valuable insights as personnel retire. Furthermore, we discuss the limitations of current LLMs, such as interpretability and handling of rare domain-specific terms, and propose strategies for improvement. This work highlights the potential of LLMs to play a pivotal role in preserving institutional knowledge and ensuring continuity in highly specialized fields.

Speaker: Dr Mariusz Sapinski (Paul Scherrer Institute)

15:30 Applications of waveform digitizers at the TPS and TLS control systems

The retrieved waveform data include pulse magnet power supply waveforms, fast current transformer waveforms, wall current monitor waveform, RF power waveforms, beam signals, and more. These waveforms are crucial for diagnosing subsystem abnormalities and for long-term observation during routine beam operations. Various types of digitizers, capable of remotely accessing waveforms, have been deployed in the TPS and TLS control systems. To enhance data acquisition capabilities and stability, the waveform digitizers have replaced outdated oscilloscopes that were damaged due to prolonged use. Each type of waveform digitizer is equipped with specific sampling rates and data lengths based on the signal properties and intended applications. High-sampling-rate (10 GSPS) digitizers are applied to capture detailed beam-related signals, while universal-sampling-rate (125/500 MSPS) digitizers are employed to record long-term signal variations in a single acquisition. This paper describes the applications of these digitizers and the development of integrated graphical user interfaces for the TPS and TLS control systems.

Speaker: Jin-Kun Liao (National Synchrotron Radiation Research Center)

15:30 Augmented Reality for Accelerator Operations: A Virtual Control Room Proof of Concept

Particle accelerator control rooms rely on fixed workstations with multiple monitors and on-site personnel, limiting operational flexibility. When experts connect remotely—whether for troubleshooting, monitoring, or collaboration—current setups often lack sufficient screen space, forcing users to toggle between interfaces and reducing situational awareness. Recent advancements in augmented reality headsets enable spatially aware virtual control rooms, allowing users to arrange and interact with multiple control panels in 3D space, improving efficiency and collaboration. In this work, we present our vision for a Virtual Control Room, addressing key user experience challenges, outlining the technical infrastructure, and demonstrating first prototype results from the Advanced Light Source.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

15:30 Beam Energy Forecasting using Machine Learning at the CLEAR accelerator

In particle accelerators, accurate and stable beam parameters are crucial for experimental success. Traditional methods for measuring parameters like beam energy often rely on invasive techniques that disrupt experiments. This paper presents a novel, non-invasive machine learning-based approach to predict beam energy using parasitic measurements, enabling real-time estimation without interference.
The method employs a predictive model optimized for one-step-ahead forecasting and uses time-series data decomposition to handle complex beam energy dynamics. Recursive prediction strategies allow the model to anticipate future variations autonomously. Preliminary results from experiments at the CLEAR accelerator demonstrate the model’s ability to capture both slow trends and rapid energy shifts, adapting to diverse experimental needs.
These findings showcase the potential of machine learning to measure beam energy, offering a real-time, non-destructive alternative to conventional methods. This approach promises significant advancements in accelerator-based applications, especially where destructive techniques are impractical.

Speaker: Antonio Gilardi (University of Naples Federico II)

15:30 Beam orbit tuning via reinforcement learning at FELiChEM

The online optimization and debugging of particle accelerator devices have always been a challenging task. Traditional manual debugging is time-consuming and labor-intensive, and there is a phenomenon of slow drift in the machine's operating state after debugging, requiring experts to repeatedly debug. With the improvement of computing power, machine learning has developed rapidly in recent years, making it possible to train more complex models. Deep reinforcement learning models, as intelligent agents, have the ability to interact with the actual environment and learn the best strategies. By interacting with the FEL environment through deep reinforcement learning models, automatic debugging of FEL can be achieved

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

15:30 Benchmarking of new approach for analyzing transverse beam emittance measurement

A recent analysis of emittance measurements highlighted the limited reliability of tools for precise method evaluation and error calculations. In this paper, a new analysis method is presented with its associated errors calculations. It is evaluated using realistic beam simulations and compared to the linear regression method commonly referenced in the literature. This new analysis method is shown to be easier to implement and provides results with a good confidence interval.

Speaker: Sophie Morard (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

15:30 Cavity beam position monitor signal matching by injection pulse

Cavity beam position monitors (CBPMs) are very high-precision devices that, in recent years, have progressed from experimental equipment to standard linac diagnostics in many prominent facilities, most notably free electron lasers. However, the high sensitivity of these devices comes at the cost of a limited measurement range, even with high dynamic range electronics. Furthermore, CBPMs need to be calibrated in situ, ideally by introducing a known beam offset, which is often impractical in large installations. This paper reports on a method to match CBPM beam signals by injecting synchronized and tightly controlled bursts of radio frequency (RF) oscillations into the sensor cavity and reading back their superposition. The method allows compensation for static beam offsets (with beam) and calibrates CBPMs electronically (no beam required), thus removing some of the operational hurdles. We discuss the first demonstration of this method at the Accelerator Test Facility 2 (ATF2).

Speaker: Mark McCallum (John Adams Institute)

15:30 Characterization of an IRRAD beam profile monitor at the CERN T8 beamline and possible improvements via cross-analysis with multiwire proportional chamber

A new Beam Profile Monitor (BPM) system has been recently developed at the IRRAD Proton Facility to monitor the high-intensity 24 GeV/c proton beam from the CERN Proton Synchrotron accelerator. Thanks to the use of a new sensor manufacturing technology based on the microfabrication of metal nano-layers and updated readout electronics based on a Charge-Sensitive Amplifier with integrated 20-bit ADC and ARM controller, this system features minimal particle interaction, improved radiation hardness and higher sensitivity than earlier solutions.
The growing users’ demand for precise irradiation of modern electronics, requiring ever more detailed beam information, is driving the introduction of future IRRAD upgrades, by leveraging on the presence of additional detector, a Multiwire Proportional Chamber, a detailed comparison-based analysis was performed to better characterize the IRRAD BPM system. It allowed us to introduce improvements in beam monitoring via advanced software and data processing. These results are crucial for future improvements at IRRAD by formulating requirements for the profile monitoring of new types of beams in IRRAD, e.g. heavy-ion and low-intensity proton beams.

Speaker: Jaroslaw Szumega (European Organization for Nuclear Research)

15:30 Characterization of four-dimensional phase space for space charge-dominated beams using novel beam diagnostic techniques and generative phase space reconstruction at the KOMAC beam test stand

Transverse phase space (x, x’, y, y’) measurement is crucial in beam physics to optimize the beam parameters. Typically, the phase space information of space charge-dominated beams can be characterized using well-established methods such as pepper-pot and movable slit-based scans. In addition, recent studies show that calibration of transfer matrix with considering space charge forces provides quantitative agreement in a solenoid scan-based emittance measurement. In this study, we characterize the space charge-dominated, 1 MeV/n proton beam at the Beam Test Stand (BTS) of Korea Multipurpose Accelerator Complex (KOMAC) using various beam diagnostic instruments such as pepper-pot, virtual pepper-pot, and multi slits. Furthermore, we investigate the usage of generative phase space reconstruction, based on neural networks and differentiable simulations, in the context of space-charge calibrated matrix computations and self-consistent beam propagation. We also discuss the comparison of the phase spaces obtained by conventional diagnostics, confirming the effectiveness of the reconstruction algorithm and advanced diagnostic methods for analyzing space charge-dominated beams.

Speaker: Moses Chung (Pohang University of Science and Technology)

15:30 Data-Driven Modeling for the Magnetic Field Prediction in Particle-Accelerator Magnets Based on Measured Electrical Parameters

The precise modelling of magnetic fields in particle accelerator magnets is essential for optimizing their performance and ensuring the accurate control of particle beams. Traditional modelling approaches require extensive multi-physics simulations and electrical and magnetic measurements. In this study, we explore using data-driven artificial intelligence models to predict the magnetic field based on the magnet's voltage and excitation current. We conducted a case study to validate this approach using dipole and quadrupole magnets from the Super Proton Synchrotron (SPS) at CERN. The results demonstrate that AI-based models can achieve accuracy comparable to traditional measurement methods. Additionally, the flexibility of AI models allows for continuous learning as new data becomes available, further enhancing the dynamic control capabilities of particle accelerators. Future work will focus on refining the models, expanding their applicability to different types of magnets, and exploring their integration into accelerator control systems for real-time field adjustments and optimization.

Speaker: Carlo Petrone (European Organization for Nuclear Research)

15:30 Demonstrating a Fisher Information based methodology for optimizing BPM placements in AS2

The next generation Australian Synchrotron project (AS2), is a proposed 4th generation light source, aims to deliver ultra-low emittance $\sim$100 pm-radians and highly coherent, bright light. Constraints on emittance place tight demands on beam optics correction techniques like linear optics of closed orbit (LOCO) and consequently constraints on accurate estimation of the beam centroid along the orbit.

In this work, we propose a Fisher Information Matrix (FIM) -based method for optimizing BPM placement. To achieve this, we use the fully differentiable accelerator code Cheetah, which integrates accelerator modelling with automatic differentiation to enable fast simulations and efficient computation of partial derivatives - including the FIM from the second derivative. Using this we derive optimal BPM placements that minimize variance in estimation of the beam centroid parameters for a segment of the AS2 system.

Speaker: Fareeha Almas (The University of Queensland)

15:30 Design and development of a beam scraper system for Siam Photon Source II

This paper presents the development of a beam scraper system for the 3 GeV storage ring of Siam Photon Source II (SPS-II). Beam scrapers are essential for removing halo particles, protecting accelerator components, and managing aperture limitations. The scraper blade material is carefully chosen for its superior thermal conductivity and mechanical strength. The design prioritizes considering wakefield impedance to minimize beam disturbances, incorporates detailed thermal simulations to ensure operational stability, and optimizes the mechanical structure for easy installation and long-term durability. This design approach significantly enhances the performance and reliability of the SPS-II beam scraper system.

Speaker: Siriwan Jummunt (Synchrotron Light Research Institute)

15:30 Design considerations of the bunch-by-bunch transverse feedback system for the CSNS RCS

The CSNS RCS (Rapid Cycling Synchrotron) is a proton accelerator designed to achieve a target beam energy of 1.6 GeV, with a typical operating intensity of 140 kW, which is expected to increase to 500 kW after the CSNS II upgrade. However, a significant current instability has been observed during the 100 kW beam operation. To mitigate this instability, techniques such as operational tuning and chrominance modulation were previously used to make the 100-kilowatt beam operate stably. In order to face the subsequent stronger instability, a bunch-by-bunch transverse feedback system is developed to mitigate the coherent lateral oscillations caused by instability and injection errors. The system consists of a beam position monitor, strip-line kicker, power amplifier, and signal processing electronics.

Speaker: Weiwen Chen (Institute of High Energy Physics)

15:30 Design of a multi-layer ionization chamber

In this paper, a multi-layer ionization chamber is designed for the measurement of 250MeV proton beam profile. The chamber is equipped with 128 X and Y channels, allowing for high-resolution profiling of the proton beam across both transverse axes. Each channel is capable of detecting ionization events, providing precise dose measurements and spatial distribution information. The design incorporates advanced materials and configurations to ensure optimal energy response and accuracy at the specified proton energy. The proposed chamber aims to enhance the accuracy of proton therapy dose verification and monitoring, enabling better patient treatment planning and quality assurance in proton beam therapy.

Speaker: Ali Najafiyan (Shahid Beheshti University)

15:30 Design of a novel high-precision beam diagnostic beamline

A novel high-precision beam diagnostic system has been designed for slice emittance and energy spread measurements. The 20-meter diagnostic platform integrates eight quadrupoles, a deflecting cavity, and an energy spectrometer, achieving 100fs temporal resolution in both operational modes through the same beamline layout. The emittance measurement mode provides 50-fold horizontal magnification, while the energy spread measurement mode reaches 1.71 keV theoretical energy resolution through optimized dispersion and screen rotation. Comprehensive error analysis confirms measurement precision of 3.05%±0.69% for relative emittance changes and 4.82±1.35 keV for energy spread variations, demonstrating the effectiveness of this flexible design for high-precision beam diagnostics.

Speaker: Ao Liu (ShanghaiTech University)

15:30 Detecting anomalies in non-static environments: continual learning applied to CERN's kicker magnet

The CERN accelerator complex relies critically on fast injection and extraction processes to transfer particle beams between accelerators via fast pulsed magnets, or kickers. Ensuring high availability is paramount, as the reliability of these systems directly impacts the large number of experiments conducted at CERN. In this paper, we propose to explore Continual Learning (CL) methods, specifically using Variational Autoencoders (VAEs), to develop an anomaly detection system for the fast kicker magnets. By continuously learning from evolving data while retaining prior knowledge, these models will be capable of detecting anomalies without the need for repeated retraining. This approach is particularly relevant for ensuring the reliability and stability of kicker magnets, where early anomaly detection is critical for preventing performance degradation.

Speaker: Francisco Huhn (European Organization for Nuclear Research)

15:30 Development of a beam profile monitor based on the YAG:Ce scintillator for a multipurpose beam diagnostic system

In this paper, a multipurpose beam diagnostic system based on a YAG:Ce scintillator is presented. This system was developed in order to measure beam profile, transverse parameters, momentum spectrum, and current of the electrostatic accelerator. The concerning issues in the beam profile monitor design such as image resolution and scintillator temperature distribution have been discussed. In order to estimate the resolution of the scintillator screen, the collision of ideal proton and electron beam with YAG:Ce scintillating screen was simulated using the Geant4 Monte Carlo code. Increasing scintillation temperature will decrease the scintillation optical yield and result in a change in beam profile, so COMSOL software was used to simulate the scintillation temperature distribution under different beam powers. The design procedure, including the handling of heat transfer and charging accumulation issues, as well as estimation and improvement of image resolution, has been investigated. After designing the beam profile monitor based on YAG:Ce,The equipment was provided and manufactured and the beam profile was measured using this diagnostic tool.

Speaker: Ali Najafiyan (Shahid Beheshti University)

15:30 Development of a DAQ system for a High Resolution cavity BPM for the future linear collider

A cavity beam position monitor (cBPM) developed by
CEA Saclay was installed at the end of the Accelerator Test
Facility (ATF) linac to evaluate the combined performance
of the monitor and its associated signal processing system.
The setup incorporates a down-conversion architecture inspired
by Royal Holloway, University of London (RHUL),
and employs a digital down-conversion (DDC) algorithm
to extract beam position. This configuration enables highsensitivity
measurements of the transverse beam position.
Preliminary results confirm successful signal acquisition
and a clear position-dependent response, validating the integrated
performance of the cBPM, analogue electronics,
and digital processing chain. The results underscore the
necessity of reliable local oscillator (LO) phase-locking to
ensure precise position determination.

Speaker: Laura Pedraza (Instituto de Física Corpuscular)

15:30 Development of a new clock phase shifter for phase measurement at the TPS

The Taiwan Photon Source (TPS) is a 3 GeV synchrotron radiation facility located at NSRRC. Superconducting RF cavities have been installed in the booster and storage rings to ramp and refill electron beam energy. In order to measure the bunch phase of each bunch relative to the RF clock of the accelerator, a bunch phase detector (BPD) system was constructed to support measurement experiments. This detector uses the I/Q demodulator approach to calculate the beam phase. The system supplies a reference clock to the ADC at the RF frequency, along with a signal at three times the RF frequency, to enable calculation of the phase difference between the beam and the reference signal. The system includes a single-board computer (SBC) which is integrated with the control system to implement the remote phase adjustment function to make the operation more convenient. The BPD has been installed in the TPS and can provide measurement data. This paper describes the efforts in implementing this system.

Speaker: Jin-Kun Liao (National Synchrotron Radiation Research Center)

15:30 Direct diode detection tune measurement in the BESSY II booster

The Direct Diode Detection (3D) method for transverse tune measurement, which was developed at CERN, has been implemented in numerous hadron machines and has recently been tested in electron machines. This method can provide orders of magnitude greater sensitivity to betatron oscillations than conventional beam position measurement approaches, which is particularly useful in fast-ramping synchrotrons such as the Booster of the BESSY~II light source. Typical systems used for tune measurement in an electron storage ring, which rely on the beam being in a relatively steady state, are not well-suited for fast-ramping machines; in order to measure the tune throughout the full acceleration ramp using conventional beam position approaches in the BESSY~II Booster, it is necessary to use large external excitation which disturbs injection into the storage ring. Here we describe tune measurement in the BESSY~II Booster using diode detectors, which allows for tune measurements during the full acceleration ramp with little to no external excitation and therefore no disturbance to user operation.

Speaker: Meghan McAteer (Helmholtz-Zentrum Berlin für Materialien und Energie)

15:30 Disentangling sudden beam loss events and fast beam abort system with the RFSoC-BPM at SuperKEKB

In the SuperKEKB/Belle-II experiment, various new physics searches are conducted by colliding 4 GeV positrons and 7 GeV electrons. Future plans aim to significantly increase luminosity, targeting an integrated luminosity 100 times higher than current levels. However, the realization of this goal is challenged by the phenomenon of "Sudden Beam Loss" (SBL), characterized by the abrupt disappearance of the beam within tens of microseconds. As presented at IPAC'24, we developed the RFSoC-BOR (Bunch Oscillation Recorder) system, based on the AMD/Xilinx RF System on Chip (RFSoC). This system enables bunch-by-bunch beam position monitoring and detailed SBL data acquisition. Using the RFSoC-BOR, we analyzed SBL events, identified key contributing factors, and gained insight into strategies for mitigation. Our findings have advanced the understanding of SBL, bringing SuperKEKB closer to higher luminosity operation. Additionally, we are extending the functionality of the RFSoC-BOR to develop a fast beam abort system that improves accelerator component protection. This presentation will cover the role of the RFSoC-BOR in SBL analysis, key insights, and progress on the fast beam abort system.

Speaker: Riku Nomaru (The University of Tokyo)

15:30 Edge-ML and targeted data processing for high-rate, attosecond XFEL diagnostics

SLAC’s upgraded Linac Coherent Light Source (LCLS-II) promises transformative 1 MHz attosecond X-ray pulse generation. To meet the demands of high-rate attosecond characterization across multiple operational modes at LCLS-II, we showcase the data processing chain for the Multi-Resolution COokiebox (MRCO) detector--a circular array of 16 multichannel plate time-of-flight spectrometers optimized through independently controlled electron flight lenses and dedicated amplifiers for precise electron signal capture. MRCO’s data processing chain integrates analog and digital co-design with targeted edge-machine learning (ML) approaches. Traditional FPGA-friendly algorithms, such as the convolution-based and discrete cosine transform-based peak-finding methods, enable real-time spectral feature extraction. Additionally, ML techniques enable denoising, sub-spike identification, and temporal profile reconstruction, advancing single-shot diagnostics and attosecond resolution. This work lays the foundation for online diagnostics, shot rejection, and feedback to XFEL controls, with implications for time-resolved studies such as X-ray pump X-ray probe experiments.

Speaker: Jack Hirschman (Stanford University)

15:30 Efficient accelerator operation with artificial intelligence based optimization methods

Tuning injectors is a challenging task for the operation of accelerator facilities and synchrotron light sources, particularly during the commissioning phase. Efficient tuning of the transfer line is essential for ensuring optimal beam transport and injection efficiency. This process is further complicated by challenges such as beam misalignment in quadrupole magnets, which can degrade beam quality and disrupt operations. Traditional tuning methods are often time-consuming and insufficient for addressing the complexities of high-dimensional parameter spaces. In this work, we explore the use of advanced AI methods, including Bayesian optimization, to automate and improve the tuning process. Initial results, demonstrated on the transfer line of KARA (Karlsruhe Research Accelerator) at KIT (Karlsruhe Institute of Technology), show promising improvements in beam alignment and transport efficiency, representing first steps toward more efficient and reliable accelerator operation. This study is part of the RF2.0 project, funded by the Horizon Europe program of the European Commission, which focuses on advancing energy-efficient solutions for particle accelerators.

Speaker: Evangelos Matzoukas (Karlsruhe Institute of Technology)

15:30 Efficient data-driven model predictive control for online accelerator tuning

Reinforcement learning (RL) is a promising approach for the online control of complex, real-world systems, with recent success demonstrated in applications such as particle accelerator control. However, model-free RL algorithms often suffer from sample inefficiency, making training infeasible without access to high-fidelity simulations or extensive measurement data. This limitation poses a significant challenge for efficient real-world deployment. In this work, we explore data-driven model-predictive control (MPC) as a solution. Specifically, we employ Gaussian processes (GPs) to model the unknown transition functions in the real-world system, enabling safe exploration in the training process. We apply the GP-MPC framework to the transverse beam tuning task at the ARES accelerator, demonstrating its potential for efficient online training. This study showcases the feasibility of data-driven control strategies for accelerator applications, paving the way for more efficient and effective solutions in real-world scenarios.

Speaker: Dr Andrea Santamaria Garcia (University of Liverpool)

15:30 Enhancing ALS injector performance through data analysis

This study presents a data-driven methodology aimed at enhancing the performance and reliability of the injector at ALS. We show a data acquisition system for capturing and analyzing the parameters affecting the injection process to find patterns and improve reliability. We analyze the recorded injection parameters to find key correlations and patterns within the multidimensional parameter space, gaining insights into injector dynamics and potential areas for optimizing the injection process. Furthermore, we present first steps towards a parametric digital twin of the ALS injector based on the recorded data to enable more precise predictions of injector behavior, facilitate rapid troubleshooting, and support the development of advanced control strategies.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

15:30 Extended phase space tomography for EOSD simulation considering crystal geometry effects

This theoretical study presents an advanced method for longitudinal phase space tomography in electron storage rings, focusing on reconstructing phase space densities from electro-optical spectral decoding (EOSD) measurements that incorporate crystal geometry effects. The EOSD crystal geometry significantly impacts the measurement signal due to signal integration along its length and interference from wake fields and Cherenkov diffraction radiation (ChDR). These effects add challenges to reconstructing the original phase space density from experimental data.
To address these challenges, we integrate two theoretical frameworks. First, we employ the Vlasov-Fokker-Planck equation to model the turn-by-turn evolution of the charge density distribution. Second, CST simulations of the bunch profile characterize the electric field inside the crystal, enabling a tailored simulation for the EOSD system at the Karlsruhe Research Accelerator (KARA). By combining these approaches, we propose a refined tomography method that more accurately reconstructs the longitudinal phase space from sensor data, effectively capturing the interplay between bunch dynamics and the EOSD system configuration.

Speaker: Felipe Donoso (Karlsruhe Institute of Technology)

15:30 Extinction Monitoring of Pulsed Proton Beams Using FPGA-Based Peak Detection

The Mu2e experiment at Fermilab imposes stringent requirements on the elimination of out-of-time beam in its pulsed proton beam - a requirement known as "extinction". We present a method to measure the out-of-time particle rates to calculate the level of extinction in the inter-pulse gaps. The proposed method utilizes an array of quartz Cherenkov radiators and photomultiplier tubes to detect particles scattered from a vacuum chamber in the M4 transfer beamline at Fermilab.

The measurement will employ a new μTCA-based FPGA system for data acquisition and signal processing, utilizing real-time peak detection algorithms to count scattered beam particles. By integrating data over many transfers, the time profile of the out-of-time beam will be resolved to fractional levels relative to that of the in-time beam. These results are compared with G4beamline simulations to validate models of beam transport, dynamics, and extinction, providing critical input for optimizing beam delivery to Mu2e.

Speaker: Ryan Hensley (University of California, Davis)

15:30 Fast cyclotron beam probe at UC Davis Crocker Nuclear Laboratory

The UC Davis Crocker Nuclear Laboratory houses a 72-inch multi-species Isochronous Cyclotron built in the 1960’s. For many years, previously unexplained beam dynamics have been indirectly observed at the cyclotron by both internal and external experimenters. Investigating these effects within the cyclotron, at the bunch level, has proven particularly challenging due to the cyclotron's harsh environment of strong magnetic fields, high radiation levels, intense RF interference, and limited space. To address these challenges, a compact segmented beam probe was developed, utilizing a scintillator array target coupled to a SiPM array positioned outside the cyclotron via fiber optic cables. This novel beam probe has enabled precise, high-speed measurements of individual beam bunches, providing data to theoretical models and deepening the understanding of beam dynamics allowing for more precise operation of the cyclotron. These advancements are driving efforts to optimize cyclotron performance for diverse applications, including isotope production, ocular melanoma therapy, and a variety of experimental research.

Speaker: Logan Knudson (Crocker Nuclear Lab)

15:30 First high-power RF tests of cavities for BESSY II with a new mTCA-based LLRF system

The 3rd-generation synchrotron light source BESSY II is undergoing a series of modernization measures to maintain its leadership role until BESSY III starts its operation, planned for in 2035. The modernization of the LLRF control systems is one of these measures in the so-called BESSY-II+ project. Prior to the deployment of the new mTCA-based digital systems to control the fundamental frequency cavities at the booster and storage ring, a test stand was set up provide the opportunity for extensive offline testing and debugging. The test stand is consists of a HOM-damped 500-MHz cavity, a 80-kW Solid State Amplifier (SSA), a mTCA crate and all the ancillary systems required for high-power RF cavity operation. In this paper we discuss the results of the high power tests in continuous-wave operation, as required for the BESSY II storage ring, and in ramped mode, as required for the BESSY II booster during beam injection.

Speaker: Andrei Maalberg (Helmholtz-Zentrum Berlin für Materialien und Energie)

15:30 FPGA board based cost-effective, robust and flexible online waveform monitors development, test and implementation at KEK Accelerator Test Facility

KEK ATF is the Accelerator Test Facility devoted to develop an advanced beam instrumentation technologies for ILC (International Linear Collider) project. There are seven main subsystems at the facility: RF-Gun laser, Linac, Beam Transport (BT), Damping Ring (DR), Extraction Line (EXT), Final Focus (FF) and Interaction Point Beam Size Monitor (IP BSM). In order to monitor laser pulse output power, bunch charge transmission between accelerator sections and background at Final Focus, the online waveform monitors based on the RedPitaya STEMlab 125-14 and SIGNALlab 250-12 FPGA boards were programmed, tested implemented at KEK ATF. This study demonstrates results of the bunch charge transmission, laser pulse output power and background level monitoring using the FPGA board based waveform digitizers. Also, the FPGA boards System-on-Chip programming and control software implementation details, as well as a pulse shaping technique, will be explained in this report.

Speaker: Prof. Konstantin Popov (High Energy Accelerator Research Organization)

15:30 High accuracy measurement of the absolute energy of the MAinz MIcrotron by undulator radiation interferometry

The Mainz Microtron is an electron accelerator, which delivers electron energies up to 1.6 GeV, with a small spread of the energy σ_beam < 13 keV. Besides a small energy spread, the high quality of the beam allows producing high coherent synchrotron radiation. The light from two spatially separated and movable light sources (undulators), can be superimposed to render an interference pattern. The ideal applications are high accuracy absolute energy measurements of the relativistic electrons. Experiments at this beam line have yet been carried out at 180 MeV, 195 MeV and 210 MeV. The radiation lies in the optical range where also Fresnel Diffraction patterns occur, which features allow very precise alignment control.

Speaker: Pascal Klag (Institut für Kernphysik)

15:30 High efficiency multi-objective Bayesian algorithm for APS-U nonlinear dynamics tuning

The Advanced Photon Source (APS) facility has just completed an upgrade to become one of the world’s brightest storage-ring light sources. Machine learning (ML) methods have seen extensive use during commissioning. One important application was multi-objective tuning of dynamic aperture and lifetime, a complex high-dimensionality task intractable with classic optimization methods. In this work we will discuss novel Bayesian optimization (BO) algorithmic and implementation improvements that enabled this use case. Namely, pre-training and uncertainty-aware simulation priors, dynamic parameter space and acquisition function refinement, and an adaptive wall-time convergence criteria. We will also show results of optimization runs from 10 to 24 dimensions, benchmarking scaling and efficiency as compared to standard MOGA and MGGPO. Given the promising performance, work is proceeding on tighter BO integration into the control room.

Speaker: Nikita Kuklev (Argonne National Laboratory)

15:30 Improvement of transverse beam size measurement using synchrotron radiation at Siam Photon Source

The Siam Photon Source (SPS) has, for several decades, implemented direct imaging with synchrotron radiation for the measurement of transverse beam size. This paper describes improvements made to the transverse beam measurement system of the SPS storage ring. A synchrotron radiation interferometer system will be integrated for monitoring of beam size alongside the direct imaging system. The system's operations will be controlled and displayed through Python programming. The results from each technique will be comparatively analyzed.

Speaker: Wanisa Promdee (Synchrotron Light Research Institute)

15:30 Insertion device correction based on machine learning models at the MAX IV 3 GeV ring

Insertion Devices (ID) in particle accelerators introduce orbit distortions that must be compensated. At MAX IV, this compensation traditionally relies on feed-forward tables which are time-consuming to measure, and sensitive to changes in accelerator settings. This study explores the use of machine learning (ML) to automate the generation of feed-forward tables without requiring extensive measurements. Using archived data from ID gaps, beam position monitors (BPM), and corrector magnets, a neural network-based model was developed to replicate the current ID compensation system. Preliminary results show that the model effectively reproduces the existing compensation behavior and suggests potential for adaptive feed-forward tables that refine themselves with online data. In parallel, alternative ML approaches focused on minimizing beam position errors are being investigated. These efforts aim to improve the maintainability of ID compensation and prepare orbit control for future optical changes and new operational scenarios.

Speaker: Michael Holz (MAX IV Laboratory)

15:30 Investigation of the leakage beam from the RF chopper using the BSM

The Japan Proton Accelerator Complex (J-PARC) linac is operated with a peak current of 50 mA to deliver the 1-MW beam to the neutron target through the rapid cycling synchrotron (RCS). One of the source of the beam loss to limit the beam power is a leakage beam from an radio-frequency (RF) beam chopper at the frontend of the linac. Since the leakage beam is presented in the unintended RF bucket, it becomes the beam loss the during the acceleration in the RCS. Recently, the bunch-shape monitor (BSM) dedicated for the low-energy beam has been developed to measure longitudinal profiles after an radio-frequency quadrupole linac (RFQ)*. It is useful to investigate the leakage beam because the BSM is located at just after the chopper. Asymmetric longitudinal profiles were observed with the BSM, but the sensitivity should be improved to observe the leakage beam. Measuring the induced current from the target probe by using the BSM in the same way as the wire-scanner monitor, the leakage beam was observed in the horizontal profile measurement. Latest results are presented with discussing the classification of the leakage beam with respect to its time scale and source.

Speaker: Ryo Kitamura (Japan Proton Accelerator Research Complex)

15:30 KEK ATF linac, damping ring accelerating field and RF-gun laser system phase&amplitude stability study

KEK Accelerator Test Facility (ATF) conducts beam instrumentation R&D for International Linear Collider (ILC) project. ATF includes 1.3 GeV normal conductivity S-band Linac and Damping Ring (DR). There are 9 S-band pulsed klystrons at Linac, which supply High-Power RF to accelerate electron beam up to 1.3 GeV, 1 CW klystron at DR. The electron beam is generated by a photocathode irradiation by a laser pulse. The laser pulse generation is synchronized with the accelerating fields by the laser system oscillator Piezo feedback. These Linac, DR High-Power RF field and laser pulse arrival time jitter and/or drift define the stability of the electron beam parameters, such as average energy, energy spread (RMS), emittance, bunch charge etc. This study demonstrates KEK ATF Linac and DR High-Power RF field phase and amplitude, as well as the laser system oscillator laser pulse arrival stability measurement results. Also, FPGA board based digital Low-Level RF phase&amplitude feedback system is described in this report.

Speaker: Prof. Konstantin Popov (High Energy Accelerator Research Organization)

15:30 Longitudinal beam size measurement at the Novosibirsk FEL

The Novosibirsk Free Electron Laser (NovoFEL) is a facility that consists of three free electron laser (FEL) systems installed on different parts of the Energy Recovery Linac (ERL). These three FELs share the same acceleration system, which enables the generation of high average electron current, typically around 10 mA. Precise measurement of the electron beam parameters is essential for monitoring the performance of the accelerator and tuning its operating modes. One of the most important parameters is the length of the electron bunch, as it directly affects the efficiency of the laser radiation generation process. This paper presents the results of experiments conducted to study the behavior of the longitudinal beam size in various Novosibirsk FEL lasers. For these experiments, we used Cherenkov radiation produced by a beam of electrons passing through a thin aerogel plate. The resulting flash of radiation was captured by a streak camera, allowing us to determine the longitudinal size of the electron beam. The results of the study on the dependence of the longitudinal beam size on various accelerator parameters are presented.

Speaker: Stanislav Reva (Budker Institute of Nuclear Physics SB RAS & Novosibirsk State University)

15:30 Machine learning driven beam emittance optimization at EuXFEL

Planned upgrades of the European X-Ray Free Electron Laser (EuXFEL) target higher photon energy and a high duty-cycle operation up to CW operation, critically depending on improvements of the beam slice emittance of the electron gun. We are addressing this challenge by the application of deep learning techniques to create an inverse model that predicts optimal parameter configurations for the photoinjector, enabling targeted control and minimization of beam emittance. This methodology involves sampling synthetic training data through comprehensive beam dynamics simulations and introduces a machine
learning-based strategy for prediction of optimal gun parameters as well as temporal pulse shaping, accommodating a family of pulse distributions including flattop and Gaussian shapes. We present results from trained neural networks with various architectures and outline our research on the invertibility of the forward model by connecting our approach to the theory of inverse problems.

Speaker: Alexander Klemps (Hamburg University of Technology)

15:30 Machine learning for the anomaly detection and characterization of the 24 GeV/c proton beam at CERN IRRAD Facility

The accurate assessment of beam quality is the most important aspect in the irradiation facilities operation such as IRRAD at CERN. The Beam Profile Monitor (BPM) sensor system developed for the high-intensity proton beam at IRRAD features minimal particle interaction, improved radiation hardness and higher sensitivity and sampling rate than previous systems. It provides a wealth of high-quality BPM data not available earlier, enabling the development of data processing more advanced than before. To take advantage already today of this upgraded BPM system’s features, we propose innovative Machine Learning (ML) techniques to adapt and improve upon existing DAQ technology.
This paper details the application study of (1) autoencoder architectures to perform the automatic pattern recognition and anomaly detection of proton beam profiles, and (2) deep learning techniques to predict relevant beam parameters. We applied this approach to a new dataset (made publicly available) of BPM data taken during the recent runs of IRRAD; our preliminary results demonstrate good performance in comparison to existing methods. This work is a first step towards the "intelligent" irradiation facilities.

Speaker: Jaroslaw Szumega (European Organization for Nuclear Research)

15:30 Machine learning-based model predictive control of the FRIB SRF

A machine learning-based model predictive control (MPC) application has been developed for the RFQ control at Facility for Rare Isotope Beams (FRIB). In this work, we extend this approach to broader applications at FRIB, the superconducting radio frequency (SRF) control. A machine learning model is trained to learn the correlations between the beam loss and the SRF signals. With the model, a MPC contoller is implemented to minimize the beam loss with high efficiency.

Speaker: Jinyu Wan (Facility for Rare Isotope Beams)

15:30 Machine learning-driven longitudinal phase space reconstruction for enhanced beam tuning at LANSCE

The Los Alamos Neutron Science Center (LANSCE) relies on accurate tuning of its Drift Tube Linacs (DTLs) to maintain beam quality and operational efficiency. This work introduces a novel machine-learning-based approach to reconstruct the longitudinal phase space (LPS) at the entrance of DTL Tank 1 using two-dimensional phase scans from Tanks 1 and 2. A Deep Neural Network trained on synthetic datasets generated by GPU-accelerated simulations integrates real-time diagnostic data to infer high-resolution LPS distributions. By solving this inverse problem efficiently, the method improves beam delivery precision while reducing operator intervention. Early results indicate that this approach can enhance LANSCE’s operational capabilities, providing a robust framework for accelerator tuning and diagnostics.

Speaker: Petr Anisimov (Los Alamos National Laboratory)

15:30 Machine learning-driven phase space reconstruction for heavy ion linac beams

This study explores the application of machine learning techniques for phase space reconstruction of heavy ion linac beams, a critical aspect of understanding and optimizing beam dynamics for advanced nuclear physics experiments. Modern machine learning methods, including neural networks and differentiable simulations, are employed to reconstruct the multidimensional phase space distribution from limited and noisy measurement data. These methods excel at modeling nonlinear relationships and inferring missing information, addressing traditional challenges in high-dimensional data processing. The framework uses beam diagnostics data, such as beam profiles and time-of-flight measurements, to train predictive models capable of accurately reconstructing spatial, angular, and energy distributions. Preliminary results demonstrate significant improvements in reconstruction accuracy compared to conventional approaches, with potential for real-time implementation. This work underscores the effectiveness of machine learning for beam diagnostics and optimization, offering a pathway to enhanced performance and efficiency in heavy ion linac operations.

Speaker: Chong Shik Park (Korea University Sejong Campus)

15:30 Machine learning-enhanced infrared imaging for temperature anomaly detection in power supplies

The performance of particle accelerators is critically dependent on the reliability of their power supplies, which can number in the thousands in many facilities. In this work, we present a method for monitoring temperature anomalies in power supplies using infrared (IR) imaging. By applying various machine learning algorithms to the IR imaging data, we develop a reliable anomaly detection system that can improve the uptime of accelerator facilities. This approach enables early detection of potential issues, facilitating predictive maintenance and enhancing overall operational efficiency.

Speaker: Osama Mohsen (Argonne National Laboratory)

15:30 Magnetic field control in the MedAustron synchrotron

MedAustron, a synchrotron-based ion therapy centre in Austria, is focused on enhancing cancer treatment performance. A key improvement opportunity lies in the regulation of the main ring bending dipoles, which currently require time-consuming procedures to ensure reproducibility and reliability of the associated magnetic fields (B-Fields). Other therapy centres globally address this through a traditional B-train or similar systems to regulate on the B-Field and mitigate parasitic effects. In contrast to that, we propose a novel approach utilising a single Hall probe measurement inside a reference magnet, fused with a magnet model to provide real-time, high accuracy estimates of the integral B-Field for regulation. This technique, combined with a tailored controller, is evaluated under typical therapy cycling conditions. The system's performance is demonstrated through metrological analysis and beam property comparisons. Most importantly, the results show the possibility of significant improvements in treatment time reduction. Ultimately, the already achievable beam position accuracy, and spill structure in the treatment rooms, enable the start of commissioning in 2025.

Speaker: Thomas Margreiter (EBG MedAustron GmbH)

15:30 Measurement of slice energy spread of a high brightness electron beam using a passive dielectric-lined waveguide structure

In this study, we investigated the possibility of using a passive dielectric-lined waveguide structure on slice energy spread measurement of femtosecond electron beam. Such diagnostic setup for a 25 MeV electron beam with a duration of a few hundred femtoseconds is simulated using IMPACT-T. The DLW acts as a passive streaker by generating traverse wakefields that deflect the electron bunch. Simultaneously, a dipole magnet serves as a spectrometer, separating the slice energy distribution, which is then visualized on YAG screen. The DLW’s wakefields significantly broaden the transverse beam profile on the screen, with the beam tail experiencing a stronger transverse kick than the head. This effect results in a beam separation on the vertical axis. To analyze the wakefields, CST simulations are used to compute wake potential excited by a Guassian beam. By proper deconvolution, the corresponding transverse wake function is obtained. This wake function is combined with IMPACT-T simulations and a 6D phase space distribution to deduce the slice energy spread. The results demonstrate a promising approach for diagnostics that helps to optimize free-electron laser (FEL) drive beams.

Speaker: Chihkai Liu (National Central Univeristy)

15:30 Measurement of the radiation damping time via optical methods

The radiation damping time is a crucial parameter that depends on the overall magnetic structure of the accelerator. Accurate measurement of this damping time can provide insights into the fidelity of the accelerator model by allowing for a comparison with calculated damping time values. In this study, we present a series of measurements of radiation damping times at the VEPP-4M and VEPP-2000 collider at BINP. In order to determine the damping time, we recorded the transverse beam profile using a digital camera. The results includes study of the damping times at revolution frequencies and different energies of the beams.

Speaker: Veronika Maior (Budker Institute of Nuclear Physics SB RAS & Novosibirsk State University)

15:30 Measurement of vertical and horizontal emittance via undulator high harmonics at the APS-U

The transition from 3rd to 4th generation synchrotron light sources can primarily be characterized by a significant reduction in horizontal emittance. This enables a nearly uniform transverse X-ray beam profile and a brilliance that approaches the diffraction limit. A consequence of the upgrade to Diffraction Limited Storage Rings (DLSRs) is that the traditional emittance measurement techniques lack the resolution required to accurately measure emittances in the picometer-radian range. At the Advanced Photon Source Upgrade (APS-U), we explore the use of high harmonics of undulator radiation for precise emittance characterization. Previously at the Advanced Photon Source (APS), vertical emittance measurements, validated through SPECTRA simulations, were performed. This drove the desire to measure the horizontal emittance at the APS-U. Simulations performed in SPECTRA and Synchrotron Radiation Workshop (SRW) guide our experimental strategy for characterization. We present measurements of both the horizontal and vertical emittance at the APS-U, including variations across different bunch timing modes. We conclude by discussing the advantages of this approach over traditional methods.

Speaker: Emmanuel Aneke (Northwestern University)

15:30 MENT algorithm for transverse phase space reconstruction at SIRIUS

The injector system of SIRIUS, the brazilian 4th generation synchrotron light source, currently operates with non-ideal injection efficiencies, which may impose limits to future top-up operation modes. Within this context, diagnostic techniques to access beam quality in the injector are essential tools for optimizations. In this work, the MENT algorithm was implemented for the reconstruction of two-dimensional probability densities, aiming to determine the electron density in the transverse phase space at the end of the LINAC. The implemented method has been validated through simulations of several distributions, demonstrating its reliability, and applied to analyze preliminary experimental results.

Speaker: Otávio Silveira (Brazilian Synchrotron Light Laboratory)

15:30 Model-based optimisation for automated multi-turn extraction tuning at the CERN Proton Synchrotron

Multi-Turn Extraction (MTE) is a resonance-based technique employed in the CERN Proton Synchrotron (PS) to split the beam in horizontal phase space before extraction to the Super Proton Synchrotron (SPS). The splitting efficiency is evaluated based on the uniformity of intensities across the beamlets, requiring fine-tuning of multiple parameters. In this paper, we investigate the influence of key parameters on MTE efficiency to improve the understanding of their impact on the process. Using a Gaussian Process model and various visualization techniques, we assess the sensitivity of the MTE efficiency to horizontal tune, transverse feedback gain, excitation frequency, beam intensity and magnetic hysteresis. Results from experiments and simulations indicate a complex, non-convex relationship between MTE performance and the parameters listed above. Additionally, external factors such as thermal fluctuations may contribute to performance variability. Our findings highlight the need for a model-based controller to counteract parameter drift, thereby ensuring consistent MTE beam quality during operation. We propose a solution supported by experimental results.

Speaker: Oleksandr Naumenko (European Organization for Nuclear Research)

15:30 MTE measurements at the ASU cryogenically cooled DC electron gun

The ASU cryogenically cooled DC electron gun represents a state-of-the-art platform for testing novel photocathodes at room and cryogenic temperatures. The key electron beam diagnostic tool of this setup is the four-dimensional (4D) phase space reconstruction using the pinhole scan technique. In this work, we use the 4D phase space measurement to extract the Mean Transverse Energy (MTE) obtained from cathodes in this gun. We also establish the limits and accuracy of the 4D phase space and emission area measurements and estimate their effects on the MTE extracted. The results, validated through simulations and complementary measurements establish the use of the 4D phase space measurement technique to obtain the MTE. Using this approach, we measure the MTE from alkali antimonide photocathodes at varying temperature and electric field conditions. This study provides a robust foundation for future experiments with the ASU electron gun and beamline, paving the way for advanced photocathode characterization under cryogenic conditions.

Speaker: Peter Owusu (Arizona State University)

15:30 Multimethod signal processing for comprehensive tune coupling characterization at Canadian Light Source

This study compares Fast Fourier Transform (FFT), Power Spectral Density (PSD), and Wavelet Analysis for detecting tune coupling at the Canadian Light Source (CLS). Data were analyzed for low coupling, 1.4%, and 2.5% high coupling regimes, focusing on frequency identification and amplitude stability in X and Y directions. FFT revealed ~15% amplitude fluctuations, complicating tune identification. PSD provided better stability, with only 4% amplitude variations. Both methods were computationally efficient, with FFT taking, 0.0103 seconds and PSD, 0.0108 seconds per calculation. Wavelet analysis preserved temporal-frequency relationships, revealing delays between X and Y frequencies of 2.38 to 4.77 microseconds in the 1.4% regime and peak periods around 18 microseconds. In high coupling, X frequencies preceded Y frequencies, with dominant frequencies showing higher amplitudes than perturbed ones. These findings demonstrate PSD's stability for tune measurements and Wavelet Analysis's ability to capture temporal dynamics, providing insights to enhance beam stability in accelerator systems.

Speaker: Prof. Mark Boland (University of Saskatchewan)

15:30 Neural networks approach for controlling a waveform pattern of the paint bump power supply at J-PARC RCS

Four horizontal paint bump magnets and two vertical paint bump magnets are used for the painting injection to produce a high intensity beam at J-PARC RCS. These paint bump power supplies are composed of the IGBT chopper units, and so the requirement waveforms can be controlled with high precision less than 1%. By using software that automatically creates input voltage (IV) patterns according to the characteristics of the power supply and direct manual adjustment of IV patterns, the current deviation of the painting pattern (PP) is less than ±0.2%.The adjustment of one PP needs about one hour and several days to adjust a total of 90 patterns with six paint bump magnets. Therefore, a reduction in adjustment time is required. In addition, to mitigate the beam loss caused by beam orbit control to a minimum level, we would like to realize a more precise current deviation. To adjust for these PP, we performed neural networks (NN) approach. By learning the IV patterns and output current patterns as training data, the highly accurate IV patterns were confirmed.The presentation reports on the preliminary training results using NN.

Speaker: Moe Sugita (Japan Proton Accelerator Research Complex)

15:30 Online analysis of proton and lead ion LHC schottky spectra

The Schottky signals encode various beam and machine parameters, such as betatron tune, chromaticity, momentum deviation and transverse emittance. In this contribution we present the architecture and the performance of the system estimating these parameters in real-time, providing the only non-invasive measurement of chromaticity at the Large Hadron Collider. The obtained results are assessed based on chromaticity drift predictions and the measurements from the independent instruments. The remaining challenges are discussed with the outlook for further development given.

Speaker: Kacper Lasocha (European Organization for Nuclear Research)

15:30 Operational results of data-driven automated intensity optimization at CERN’s LEIR

At CERN’s Low Energy Ion Ring (LEIR), high beam intensities are achieved through phase space painting with up to eight multi-turn injections from the linear accelerator Linac3. After each injection, the beam is cooled and stacked in longitudinal phase space using an electron cooler. During beam operation, key parameters such as RF cavity phases in the linac, the LEIR electron cooler gun voltage, and various magnetic field strengths along the transfer line must be frequently adjusted to compensate for the injection performance degradation occurring over time. The primary cause is the aging of the stripper foil, a thin carbon plate which strips off electrons from the passing ions, altering the energy of the beam injected from the linac. Time of flight measurements in the linac and Schottky signals in the ring provide the necessary diagnostics for correcting the performance degradation and can be encoded to provide a state for an optimizer. In this paper, we compare several data-driven methods, such as Bayesian Optimization and Reinforcement Learning for designing an autonomous controller to optimize and maintain injection performance during both beam commissioning and physics runs.

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

15:30 Optimization of Siam Photon Source storage ring using Badger

Badger is optimization software created for the purpose of real-time accelerator tuning and operation. A range of optimization algorithms are available on this platform, implemented with both graphical and command-line user interfaces. This study shows the improvements in beam size, beam lifetime and related parameters at the Siam Photon Source storage ring following the application of Badger. The optimization results will be presented.

Speaker: Surakawin Suebka (Synchrotron Light Research Institute)

15:30 Optimizing collimator positions using bayesian optimization in the Fermilab MI-8 transfer line

Collimators are used to minimize losses and to remove particles that would otherwise get lost downstream and irradiate the machine. Finding the optimal jaw positions is time consuming and with the upstream beam properties changing, the collimation settings would need to be readjusted each time. Therefore, a method to optimize collimator positions and to operate them at full capacity in a short time is required for loss control downstream. A study of collimator positions was conducted and a machine learning (ML) model was developed to predict optimal collimator positions. Bayesian Optimization (BO) was used to calculate new jaw positions from the ML model. The results of BO and usage of ML for better performance of the collimation system are presented in this paper.

Speaker: Betiay Babacan (Fermi National Accelerator Laboratory)

15:30 Orthogonal dual-slit emitttancemeter for the C-band photocathode RF-gun

To enhance the performance of next-generation X-ray Free Electron Lasers (XFELs), it is crucial to produce high-quality electron beams with low emittance, particularly for attaining emittances below 0.2 mm.mrad for 100 pC bunch charges. This study introduces an emittance measurement method using an orthogonal dual-slit technique, aimed at enhancing measurement efficiency and achieving the necessary measurement accuracy for such small emittances. An emittance meter based on this method has been designed for a C-band photocathode RF gun at the CSNS campus. Finally, we present numerical simulations to optimize the primary parameters of the emittance meter, focusing on beam drift distance, combined with the motion accuracy of the stepper motor and the expected resolution of the optical observation system to ensure the accuracy of the emittance measurement.

Speaker: Weiwen Chen (Institute of High Energy Physics)

15:30 Performance assessment of profile monitors at CERN’s LHC using systematic analysis tools

In this paper, we investigate statistical and systematic tools to establish performance benchmarks for future beam profile measurement tools, using extensive data from both prototype and legacy Beam Wire Scanners and the Beam Synchrotron Radiation Telescope at the LHC. We detail direct and comparative analyses, including variability in beam size measurements, positioning accuracy, and profile shape fidelity relative to theoretical models, with particular focus on non-Gaussian tails influenced by the beam halo effect. This work establishes a foundation for systematic performance assessment applicable to both current and next-generation profile measurement tools.

Speaker: Nabil El-Kassem (European Organization for Nuclear Research)

15:30 Possibilities for performance enhancement of a compact TDS at FLUTE

A compact transverse-deflecting system (TDS) is being commissioned at the test facility FLUTE (Ferninfrarot Linac- und Test-Experiment) located at the Karlsruhe Institute of Technology (KIT). It has been proposed for diagnostics of short electron bunches. The idea of the technique is to use terahertz (THz) radiation, produced by the tilted-pulse front method using a part of the facility’s photoinjector laser, amplified by a sub-mm scale resonator for streaking of the electron bunch. Two types of resonators and their arrays have been studied: inverse split-ring and tilted slit resonator.
Since the temporal resolution of this technique depends strongly on the electric field strength in the resonator gap, it would be desirable to increase this field strength. A horn-antenna-like device placed near the resonator has been proposed and simulated for this purpose. Simulations and geometrical parameter optimization have been performed using CST MICROWAVE STUDIO and will be presented in this contribution.

Speaker: Sergei Glukhov (Technical University of Darmstadt)

15:30 Prediction of electron beam parameters through diffraction images

Achieving precise and real-time diagnostics of electron beam characteristics is critical for enhancing the performance of ultrafast electron diffraction (UED) and electron microscopy (UEM) techniques. Key parameters such as bunch size, emittance, energy spread, and spatial pointing jitter directly influence the quality and accuracy of experimental results. Traditional diagnostic methods often lack the ability to provide continuous, real-time, and non-intrusive monitoring, limiting their effectiveness. This work presents a machine learning (ML)-based approach that utilizes a small dataset of known beam parameters in combination with real-time diffraction image data recorded during experiments to predict electron beam characteristics for each run. This approach enables continuous optimization of beam stability without interfering with the experiment and facilitates real-time updates to UED parameters during data collection. As a result, it significantly improves the precision, reliability, and overall performance of UED and UEM experiments.

Speaker: Jiapeng Li (Huazhong University of Science and Technology)

15:30 Preliminary commissioning results of the LW prototype at CSNS

China Spallation Neutron Source (CSNS) accelerator complex will employ a new superconducting accelerating section to provide high beam power. To prevent contamination of the superconducting cavity surface caused by sputtering, shedding, or melting of medium materials during interceptive beam measurements, the second phase of the China Spallation Neutron Source (CSNS) superconducting linac section will adopt laser stripping technology for transverse distribution measurements of the negative hydrogen beam at nine stations. This paper describes the design of LW prototype including laser parameters, optics transmission and simulation of laser-beam interaction. And the preliminary results of the profile measurement where beam energy is 80MeV are also presented.

Speaker: Biao Zhang (Institute of High Energy Physics)

15:30 Preliminary investigation on single-pixel Schottky diode based ultra-broadband THz detectors with ps-scale temporal resolution for future BCMs

A Terahertz (THz) transition radiation monitor, as part of a Bunch compression monitor (BCM), is implemented for longitudinal bunch diagnostics at FELs such as ELBE, FLASH, or EuXFEL. Pulse energy measurements are typically carried out after each bunch compressor stage using coherent diffraction radiation (CDR) in the THz domain and pyroelectric detectors. For higher repetition rates in the MHz range, complex correction algorithms must be applied to correct signal pileup of the pyro-electric detector output, as well as limited signal-to-noise ratio, which can be overcome by using THz detectors with ultra-flat frequency response up to several THz. This work exhibits preliminary studies on developing an ultra-flat frequency response THz spectrometer. We present the developed single-pixel Schottky diode-based THz detector capable of single-shot measurements with a response time of 28.5 ps and IF bandwidth of $\sim$70 GHz. Further, the simulation result from the Schottky diode parameters is presented.

Speaker: Mr Rahul Yadav (Technical University of Darmstadt)

15:30 Progress towards longitudinal bunch profile monitor at the Argonne Wakefield Accelerator employing phase diversity electro-optic sampling

Precise measurement of an electron bunch’s longitudinal profile is critical for wakefield accelerators as shaped electron bunches can improve transformer ratios in collinear wakefield acceleration. Electro-Optic sampling of terahertz (THz) radiation from the bunch is one of the most attractive approaches to provide a view into the structure of a relativistic electron bunch due to its non-destructive nature. Recent developments in spectral encoding methods have shown that Phase Diversity Electro-Optic Sampling (DEOS) can accurately retrieve profiles from both sub-picosecond bunches and those requiring long sampling time windows near the traditional resolution limits. We report the progress on DEOS measurements using coherent transition radiation (CTR), as well as simulations of retrieved THz fields from arbitrary shaped electron bunches using various crystal and probe-laser configurations.

Speaker: Spencer Kelham (Northern Illinois University)

15:30 Recent diagnostic upgrades at the Solaris storage ring

This work summarizes the most significant diagnostic upgrades that have been implemented, as well as those currently under development, at the Solaris synchrotron facility. These include the installation, startup, and initial testing of a Bunch-by-Bunch Feedback (BBF) system that is currently being implemented at the Solaris synchrotron. Once operational, the BBF system will provide real-time corrections on a per-bunch basis, significantly enhancing beam stability. Efforts are also underway to develop a system for measuring the vertical and horizontal tunes without disturbing the electron beam. Additionally, a beam loss monitoring system is being developed and installed. Complementing these activities, numerous diagnostic scripts have been created, including those that utilize fast acquisition and turn-by-turn data from beam position monitors.

Speaker: Roman Panas (SOLARIS National Synchrotron Radiation Centre)

15:30 Results from validation experiment for three-dimensional spiral beam injection scheme

A three-dimensional spiral beam injection scheme* has been developed since 2014. This scheme is for accumulating a charged particle beam with relativistic energy in a sub-meter storage ring to realize for the J-PARC Muon g-2/EDM experiment (E34). Prior to the E34 experiment, we conducted a demonstration experiment utilizing 80 keV pulsed electron beam generated by an electron gun**. The beam passed through a transport line of three rotating quadrupoles and was accumulated in an 80gauss solenoid magnet at the center fiducial volume with a diameter of storage orbit only 24cm. Now we have successfully accomplished (1) a strongly X-Y coupled beam phase space to inject into the axisymmetric solenoid magnetic field, (2) a weak focusing magnetic field potential within the storage region at the center of the solenoid magnet, (3) a pulsed magnetic field kick to guide the beam trajectory into the storage region, and (4) beam diagnosis in the storage area. In this presentation, we will report the experimental results of successful storage in an ultra-compact ring, and improvements for the actual storage ring for E34 based on this knowledge gained from 10 years of demonstration experiments.

Speaker: Hiromi Iinuma (Ibaraki University)

15:30 Selecting 1D projections for 2D tomography reconstruction

Previous works on reconstructing the 4D phase space using tomography require optimal selection of projection views to achieve accurate reconstruction. In 2D reconstruction, the process is straightforward, as an object can be evenly sampled by dividing the angles evenly. However, extending this concept from 2D to 4D is not intuitive. This work demonstrates that quaternions can be used to more effectively describe views in 4D and introduces the Fibonacci Flower algorithm and repulsive force algorithm to evenly space views in 4D space in order to achieve higher reconstruction accuracy.

Speaker: Anthony Tran (Facility for Rare Isotope Beams)

15:30 Stand-alone operation of the dual-core cryogenic current comparator for FAIR

The Cryogenic Current Comparator (CCC) is a superconducting device for measurement of low intensity beams with magnetic fields in the range of fT. It uses a Superconducting Quantum Interference Device (SQUID) as an ultrasensitive magnetometer and an elaborated superconducting shield for its protection from external magnetic fields. The system is operated in a helium bath cryostat, which has to fulfill many requirements, such as being non-magnetic, pressure/temperature stable (mK), vibration dampening, UHV fit, bakable, compact and accessible for maintenance and repair.
First operation of a CCC as beam current monitor was achieved in the 90s at GSI. The idea has been updated for measurement of slow extracted beams and exotic ions at FAIR, and since 2014 there has been steady optimization by an international collaboration of expert institutes. Looking at noise figures and current resolution as well as practical applicability and costs, a Dual-Core CCC (DCCC) has turned out as best candidate for FAIR. In parallel to detector development the cryostat has been investigated and improved. It has recently achieved stand-alone operation, which is a main requirement for FAIR.

Speaker: Thomas Sieber (GSI Helmholtz Centre for Heavy Ion Research)

15:30 Study of Cherenkov diffraction radiation from radiator with periodic structure in THz-region

We have studied classical radiation from relativistic electrons at a facility, test accelerator as a coherent terahertz source (t-ACTS), the Research Center for Accelerator and Radioisotope Science (RARiS), Tohoku University. Cherenkov radiation is generated when a relativistic charged particle passes through a dielectric medium, while Cherenkov diffraction radiation (ChDR) is emitted when the relativistic charged particle passes near the dielectric medium. In general, the ChDR spectrum is broadband. However, when a periodic structure is used as a radiator, interference effects can monochromatize the ChDR. At t-ACTS, a proof-of-principle experiment in the THz region was conducted using a high-density polyethylene (HDPE) radiator with a periodic structure. We successfully measured ChDR from radiator with periodic structure and achieved narrowband ChDR (NbChDR) in the THz region. This paper will discuss the characteristics of NbChDR in the THz region, as observed at t-ACTS.

Speaker: Ken-ichi Nanbu (Tohoku University)

15:30 Study of laser-beam arrival time synchronization towards sub-picosecond stability level

In order to achieve laser pulse to electron beam arrival time sub-picosecond stability at the accelerator facilities, a new Low-Level Radio-Frequency system clock generators synchronization architecture is currently under investigation in collaboration between KEK (Japan) and IJClab (France). The system is based on the 10 MHz frequency generator (Stanford Research System), White Rabbit Switch, SkyWorks Si5362 clock generator and IDROGEN boards.
This report demonstrates the measurement results of the long-term and short- term synchronization between clock generators. Also, the architecture details are discussed in this report.

Speaker: Prof. Konstantin Popov (High Energy Accelerator Research Organization)

15:30 Synchronous phase measurement and study at the Taiwan Photon Source

A bunch-by-bunch synchrotron phase detector system has been implemented to investigate the synchronous phase behavior of the storage ring at the Taiwan Photon Source. This detector employs I/Q demodulation to cal-culate the beam phase on a bunch-by-bunch basis. The acquired data is integrated into the accelerator control system, visualized through a graphical user interface, and made available for further analysis. Independent component analysis (ICA) is employed to identify under-lying sources. For a trapezoid-like filling pattern, transi-ent beam loading effects are clearly observed in the flat-top region, whereas significant phase variations occur along the sloped edges of the pattern. During the beam decay period, an in-phase synchrotron phase oscillation at 7 kHz is observed, which originates from the rotation frequency of the radio-frequency transmitter. During injection, three distinct modes are identified through ICA decomposition. Among them, the amplitude of the syn-chronous oscillation mode shows a strong dependence on the injected bucket address.

Speaker: Chih-Hsien Huang (National Synchrotron Radiation Research Center)

15:30 Terahertz streaking detection for longitudinal bunch diagnostics at FLUTE

The Karlsruhe Institute of Technology is currently exploring a compact method of longitudinal electron bunch diagnostics with femtosecond resolution that has recently been demonstrated for other parameter ranges. The experimental setup utilizes a THz-based streaking approach with resonator structures, achieving both high compactness and efficiency. In this paper, we report on the experimental observation of streaking signals with our Compact Transverse Deflecting System, which has been successfully tested using two different resonators, an Inverse Split-Ring Resonator and a Tilted-Slit-Resonator.

Speaker: Matthias Nabinger (Karlsruhe Institute of Technology)

15:30 Test of the large-diameter CNT wire for the high-intensity beam diagnostics

In particle accelerator complex, measurement of the beam profile monitor is important to mitigate the beam loss in a high-intensity beam linac. However, traditional metallic wires in wire scanner monitor (WSM) face thermal challenges with high energy deposition leads to rapid break. Since the CNT wire has a high-temperature tolerance and a small energy deposit due to the low density compared with the tungsten wire, it is selected as strong wire to measure high intensity beam. With the development of carbon nano technology, a new production process for wire scanner is introduced. Besides, this paper examines the thermal durability of carbon nanotubes (CNT), carbon fiber. And the details of the study of CNT wire scanner monitor at CSNS are also presented.

Speaker: Biao Zhang (Institute of High Energy Physics)

15:30 The efforts on beam stability improvement in TPS

This report discusses various efforts to improve beam stability at the Taiwan Photon Source. The Fast Orbit Feedback (FOFB) system is essential for maintaining beam stability in the light source. Considering the trade-off between FOFB reliability and performance, we optimize the FOFB parameters to achieve better orbit stability in the TPS. Occasional spikes in the Beam Position Monitor (BPM) readings are observed in a few BPM pick-ups and it would degrade the efficiency of the FOFB system. The probability of these spikes occurrence could be related to the different filling patterns and beam currents. A schedule for replacing these BPM buttons will be established. Additionally, the effect of various signal processing schemes on the beam is also examined.

Speaker: Pei-Chen Chiu (National Synchrotron Radiation Research Center)

15:30 The Issue with XBPM2 in the TPS Front End

Two sets of blade-type beam position monitors (XBPMs) are installed in the Taiwan Photon Source (TPS) front-end. The upstream XBPM, referred to as XBPM1, has been calibrated and can calculate the photon beam center position. The downstream XBPM, referred to as XBPM2, encountered difficulties during calibration. It was unable to obtain an effective linear range. Adjustments to the blade spacing and alternative calibration methods were explored to address this issue. These details will be discussed in the article.

Speaker: Chia-Mu Cheng (National Synchrotron Radiation Research Center)

15:30 The journey towards a specialized text embedding model for accelerator physics

We present PhysBERT and AccPhysBERT, specialized sentence-embedding models trained on 1.2 million arXiv physics papers and fine-tuned for accelerator physics, respectively. Evaluation across retrieval, clustering, and similarity tasks shows gains of up to 12\% over general-purpose models for physics corpora and 18\% for accelerator-specific tasks. Applications include semantic reviewer–paper matching, Retrieval-Augmented Generation for control-room logbooks, and rapid sub-domain adaptation. We analyze key design choices—data curation, masking objectives, and contrastive fine-tuning—and outline strategies for continual adaptation, providing a blueprint for domain-specific embeddings in the physical sciences.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

15:30 The online emittance monitor at Taiwan Photon Source

This study summarizes the X-ray pinhole camera results from two recently constructed diagnostic beamlines. We provide updated emittance and energy spread measurements for the TPS storage ring and implement online measurements for routine operational monitoring.

Speaker: Chun-Shien Huang (National Synchrotron Radiation Research Center)

15:30 Time-varying Bayesian optimisation for continual optimal injection in the CERN PS Booster

The Proton Synchrotron Booster (PSB) receives 160 MeV H- ions, which are converted to protons at injection via a charge exchange mechanism, an upgrade that allows the production of low-loss high-intensity beams (> 10^13 per ring). To mitigate losses due to space charge, horizontal phase-space painting is performed with a system of fours kickers whose pulse is customisable via time and amplitude parameters.
Recent work has shown that classical optimisation algorithms can find the optimal parameter values on both a digital twin and the real machine. However, these techniques: do not handle system-state time variations, do not continually update the parameters during operation, require non-negligible dedicated beam time and are usually not robust to observation noise.
We suggest time-varying Bayesian optimisation and show that it addresses each of the previous issues at low development and deployment cost. This work improves the operation of the PSB and contributes towards the goal of automating the operation of particle accelerators.

Speaker: Francisco Huhn (European Organization for Nuclear Research)

15:30 Top-up safety simulations for Elettra 2.0

A comprehensive program of tracking studies has been carried out to ensure that no train of injected electron bunches can traverse an open beamline during top-up operations at Elettra 2.0. The analysis explored various error scenarios, considering realistic magnetic field variations, trajectory shifts, aperture constraints, and energy deviations. This paper presents the tracking techniques employed, the scenarios investigated, and the proposed interlock systems designed to ensure safety during top-up operations.

Speaker: Stefano Krecic (Elettra-Sincrotrone Trieste S.C.p.A.)

15:30 Toward autonomous control: reinforcement learning for improving CLEAR accelerator performance

Particle accelerators like CLEAR (CERN Linear Accearator for research) are essential tools in advancing various scientific fields. Automating their operation to ensure stability and reproducibility is crucial for future large-scale projects. This paper explores the first steps toward autonomous control of the CLEAR beamline, focusing initially on beam steering and advancing to complex tasks like quadrupole alignment, vital for operational stability. Reinforcement Learning (RL) agents that adapt in real-time via beam screens measurements were trained and tested. The approach is optimized for sampling efficiency, addressing the high cost and invasiveness of data collection in accelerator environments. The method enables single-shot optimization for real operations, reducing the need for manual intervention.
Results show that a few hours of training suffice for effective single-step corrections in the latter part of the CLEAR beamline, inspiring further development by the CLEAR research team.

Speaker: Antonio Gilardi (University of Naples Federico II)

15:30 Toward low multiplicity energy controllable beams at the CLEAR facility

We report on tests to achieve low multiplicity (single electron) at the CLEAR facility with a well defined particle energy. This can be achieved by a set of three collimators around a dipole magnet. These collimators reduce the charge of the beam and they give three degrees of freedom, allowing to control the position, angle and energy of the selected particles.

Speaker: Nicolas Delerue (Université Paris-Saclay, CNRS/IN2P3, IJCLab)

15:30 Toward online learning of a cavity mechanical model for improved resonance control

The energy consumption of particle accelerators becomes an important issue nowadays. One option to address this is to employ cavities with a very high quality factor. Despite its energy saving potential, such quality factor poses a serious control problem, because the cavities become very sensitive to noise affecting their resonance frequency. A resonance controller is thus needed. There have been many attempts to design such a controller, using both model-based and model-free approaches. Yet the problem still remains an open issue. An important aspect that is apparently missing in existing solutions is a real-time adaptation to plant variations. Specifically, variations in the frequency of unwanted mechanical oscillations that perturb the cavity. In this contribution, we show the dependency of these oscillations on various operating conditions. By doing so, we motivate the adoption of a machine learning-based adaptive modeling which learns the cavity dynamics online. Such modeling is expected to improve the performance of the resonance controller by making it more robust to plant variations.

Speaker: Andrei Maalberg (Helmholtz-Zentrum Berlin für Materialien und Energie)

15:30 Trajectory steering for DC beams at the CERN SPS using reinforcement learning based on intensity measurements

The slow extracted beams at the CERN Super Proton Synchrotron (SPS) are transported over several 100 m long transfer lines to three targets in the CERN North Area Experimental Hall. The experiments need intensity fluctuations to be entirely eliminated over the roughly 5 s particle spill, requiring full debunching of the extracted beams. In this environment, secondary emission monitors (SEMs) have to replace the conventional beam position monitoring systems that rely on RF structure, with the intensity difference on split secondary emission foils used to indicate the beam position. Traditional trajectory correction algorithms however fail when the beam ends up on a single foil. This paper summarises successful first tests with reinforcement learning (RL) to learn to correct the trajectory based on foil intensity measurements. The RL agents were trained in simulation and then successfully transferred to the real accelerator environment. Results of the application of the trained RL agents for the alignment of moveable split foils in front of the targets will also be presented.

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

15:30 Uncertainty-Quantified Machine Model Construction Using Physics-Informed Gaussian Processes and Bayesian Optimization

To construct a closed orbit model for an accelerator ring with intrinsic uncertainty quantification from orbit measurements, a physics-informed Gaussian Process model is proposed based on a stochastic ensemble of MAD-X lattices. Key advantages compared to LOCO (Linear Optics from Closed Orbits) include (1.) uncertainty-enabled orbit prediction in between BPMs (beam position monitors), (2.) fitting of a parameter distribution (dipole-like field errors) which inherently models uncertainty, (3.) incorporation of measurement uncertainty from BPM noise, and (4.) an active learning approach which can be more sample efficient than measuring an orbit response matrix. A case study is presented for the GSI heavy ion synchrotron SIS18 with various simulated applications, in particular constructing an effective machine model with minimal orbit uncertainty around the ring, and orbit correction to achieve minimal deviation at a specific location such as, e.g., the septum to control beam loss during slow extraction. This physics-inspired Gaussian Process regression approach shows potential to be applied to optics correction and further applications beyond closed orbit correction.

Speaker: Adrian Oeftiger (University of Oxford, John Adams Institute for Accelerator Science)

15:30 Unified differentiable digital twin for the IOTA/FAST facility

As the design complexity of modern accelerators grows, there is more interest in using advanced simulations that have fast execution time or produce insights about accelerator state. One notable example of additional information are gradients of physical observables with respect to design parameters produced by differentiable simulations. The IOTA/FAST facility has recently begun a program to implement and experimentally validate a unified start-to-end differentiable digital twin to serve as a virtual accelerator test stand, allowing for rapid prototyping of new software and experiments with minimal beam time costs. In this contribution we will discuss our plans and progress. Specifically, we will cover the selection and benchmarking of both physics and ML codes, the development of generic interfaces between device models and surrogate or physics-based sections, and the export of the parameters through either a deterministic event loop or a fully asynchronous EPICS soft input/output controller. We will also discuss challenges in model calibration and uncertainty quantification, as well as future plans to support larger proton accelerators like PIPII and Booster.

Speaker: Nikita Kuklev (Fermi National Accelerator Laboratory)

15:30 Using machine learning techniques for BGI-based profile measurements at the CERN PS

The Beam Gas Ionization (BGI) instrument provides a non-destructive method for monitoring transverse beam profiles by detecting free electrons produced during beam-gas ionization. Utilizing a Timepix-family detector, the BGI setup at the CERN Proton Synchrotron (PS) includes two instruments dedicated to horizontal and vertical plane measurements. However, the quality of these measurements is often compromised by artifacts, such as beam losses, which degrade profile quality, make the analysis significantly more difficult and ultimately affect the instrument performance. To address these challenges, this contribution explores the application of machine learning techniques for effective background removal. Both supervised and unsupervised approaches are evaluated on data acquired from the operational systems to improve the accuracy and reliability of the reconstructed profiles.
Furthermore, the computational performance and time complexity of these methods are evaluated to ensure that the proposed solutions are compatible with the operational requirements of the BGI system.

Speaker: Manuel Gonzalez Berges (European Organization for Nuclear Research)

15:30 VHEE FLASH radiotherapy: cutting-edge research at CLEAR, the CERN Linear Electron Accelerator for Research

With the current availability of cost-effective and compact electron LINACs operating in the 100-200 MeV energy range, there has been a growing interest in using Very High Energy Electron (VHEE) radiotherapy (RT) for cancer treatment. A particularly intriguing aspect is the Ultra High Dose Rate (UHDR) or FLASH dose regime, which focuses on damaging cancerous cells while sparing healthy tissues. VHEE beams are well-suited for FLASH RT, given their deep penetration and high beam current, making them effective for treating large, deep-seated tumors.
The CLEAR (CERN Linear Electron Accelerator for Research) facility has been at the forefront of exploring VHEE and FLASH RT, conducting numerous unique experiments in collaboration with multidisciplinary user groups having experience in dosimetric, chemical, and biological studies. This paper introduces recent measurements, techniques, and methods used to observe the FLASH effect at CLEAR.

Speaker: Pierre Korysko (University of Oxford)

15:30 Vibration monitoring of water pumps for anomaly detection

In accelerators facilities, unexpected failures of water pumps can lead to overheating, unplanned downtime, and costly repairs. In this study, we present a novel approach for real-time monitoring of water pump vibrations to detect anomalies indicative of impending mechanical failures. We employ simple vibration sensors combined with machine learning algorithms to identify patterns and deviation from normal operating conditions. Implementation of this anomaly detection framework can significantly enhance the operational efficiency and uptime of accelerator facilities by reducing unplanned outages and extending the lifespan of water pump equipment.

Speaker: Osama Mohsen (Argonne National Laboratory)

15:30 Virtual temperature measurements of ferrite in in-vacuum kicker magnets

The Large Hadron Collider (LHC) Injector Upgrade project has achieved unprecedented beam brightness levels, to fulfill the High Luminosity LHC requirements. This higher intensity has introduced significant challenges for some of the Super Proton Synchrotron (SPS) kickers, specifically concerning beam-induced heating and vacuum rise due to electron cloud.
The primary concern is the integrity of the ferrite within the kicker magnets, which is critical to the system's operation and availability. Currently, temperature monitoring relies on temperature probes (PT100) installed on the magnet's frame, but these do not provide direct measurements of ferrite temperature. To address this limitation, we present a method using deep learning techniques to develop a virtual temperature sensor, enabling real-time monitoring of ferrite temperatures across the kicker module. We apply this approach to some of the SPS injection kicker family, the so-called MKP-S, and discuss the general applicability of the method to other systems.

Speaker: Francisco Huhn (European Organization for Nuclear Research)

15:30 VSlib: A C++ library for next-generation voltage source control at CERN

The ongoing upgrades to CERN power converters pose new challenges to the converter control hardware that require a next-generation embedded control computer: the Function Generator/Controller 4 (FGC4), currently in development. The hardware is based on an AMD Zynq UltraScale+ MPSoC System-on-Chip (SoC), featuring a quad-core A53 ARM-architecture CPU, with one bare-metal core dedicated to the voltage source control. To fulfil the goal of high-reliability control in this integrated environment, a C++20 library to run on bare-metal, called VSlib (Voltage Source library) has been developed. The library is a toolkit providing all the necessary building blocks for regulation algorithms, as well as communication with other bare-metal and Linux-running cores of the SoC. A dedicated GUI was created to facilitate configuration of library parameters. The main focus was placed on high performance, determinism, and reliability. The library was developed according to best industrial practices, including version control, static analysis, and automated unit testing, with tests against expert models using Hardware-in-a-Loop simulator of a power converter, and continuous deployment.

Speaker: Dominik Arominski (European Organization for Nuclear Research)

17:10 Application of Bayesian optimization for the TLS booster extraction

Bayesian optimization is a method for performing global optimization on black-box functions using Gaussian processes and an acquisition function. In accelerator parameter tuning, when the number of adjustable parameters is large, finding the global optimal parameters can be time-consuming and often relies on the operator’s experience. Bayesian optimization is well-suited for such scenarios. In this report, we take the booster extraction of the Taiwan Light Source (TLS) as an example, selecting six key adjustable parameters to optimize the extraction efficiency from the booster ring to the transport line. The preliminary test results and implementation details will be discussed in this paper.

Speaker: Zong-Kai Liu (National Synchrotron Radiation Research Center)

15:30 → 17:30 Thursday Poster Session: THPS

Thursday Poster Session

15:30 A hybrid LINAC low level RF control system for FRANZ

The FRANZ linac, consisting of a coupled RFQ-IH cavity and a subsequent CH rebuncher, requires an LLRF system with moderate performance demands. These include amplitude control to maintain a constant field in the cavity, constant phase synchronization between the accelerator and rebuncher, and plunger control to stabilize the cavities frequency at 175 MHz. Given the dead time from LLRF RF output to probe input is approximately 150 ns and the system operates in cw or 1 ms pulsed mode, a decision was made to design a system with a reaction time of 1 µs.
To ensure flexibility, the system was designed with digital control. Consequently, an analog-digital hybrid system was implemented. The RF signal processing is performed using classical analog components, while the control and readout of the analog signals are managed by a ZYNQ SoC, which combines FPGA and ARM processors.
The first proof-of-concept prototype for amplitude control, including reflection and vacuum monitoring, has been successfully operational with the RFQ since late 2023. Development of the next version, which will include phase and plunger control, is underway and is expected to undergo beam testing in 2025.

Speaker: Christopher Wagner (Goethe University Frankfurt)

15:30 A multichannel Frequency Scanning Interferometry system for large scale metrology of accelerator components

In the frame of the High-Luminosity LHC (HL-LHC) project at CERN, a series of sensor solutions based on Frequency Scanning Interferometry (FSI) has been proposed for the alignment and monitoring of accelerator components along a total length of more than 800 m. The adoption of FSI technology reduces the overall cost of alignment installations, mitigates the impact of environmental noise, and limits the space required for signal cables. A development strategy for multi-channel interferometers, covering over 500 diverse FSI sensors has been put in place.
This paper deals with the development and testing of the FSI interferometer. Initially, a prototype with 16 channels was installed and qualified. Following successful qualification tests, larger-scale implementations with 32 and 64 channels were deployed, enabling comprehensive tests with the entire spectrum of FSI sensors installed on a movable component. This process prepares for the deployment of the final 256-channel interferometer for the HL-LHC. This contribution presents details of the interferometer solution, encompassing optics, electronics, and software design, along with the results and analysis of the system tests.

Speaker: Mateusz Sosin (European Organization for Nuclear Research)

15:30 A new EPICS based frequency synthesizer and power control system for the H¯ RF Ion Source at ISIS

A Low-Level RF and Power Control system based on EPICS has been developed for the new H¯ RF Ion Source on the Pre-Injector Test Stand at ISIS Spallation Neutron and Muon source, UKRI-STFC Rutherford Appleton Laboratory. The Ion Source LLRF system provides a 2 MHz signal to a Solid-State 100 kW RF Amplifier that drives the Ion Source Plasma, the changing Plasma load requires fast Frequency agility and closed loop Power Control. This paper will detail the design and performance of the LLRF system.

Speaker: Robert Abel (Science and Technology Facilities Council)

15:30 A novel calibration method for the High Luminosity LHC wire positioning system sensors

The High Luminosity-Large Hadron Collider (HL-LHC) is an ambitious project aiming to upgrade the LHC to achieve substantially more collisions to increase its potential for new discoveries after 2030. As part of this upgrade, 220 m of new components will be installed on both sides of the interaction points of the ATLAS and CMS experiments. The upgrade includes the installation of over 300 Wire Positioning System (WPS) sensors. Each sensor must be calibrated individually on-site, requiring a fast, accurate, portable and user-friendly calibration bench. This paper introduces a new mobile calibration bench capable of performing both relative and absolute calibrations simultaneously and to determine the absolute polynomial coefficients unique to each sensor. It details the underlying mathematical framework, preliminary test results, and highlights the advantages over the previous generation of test benches. The paper also presents the return of experience gained from the first field tests.

Speaker: Mateusz Sosin (European Organization for Nuclear Research)

15:30 A versatile low level RF controller design for FRIB and extended projects

The digital LLRF controller for the Facility for Rare Isotope (FRIB) project was designed to accommodate various cavity types with six distinct frequencies ranging from 40.25 to 322 MHz. The cavities also adopt different types of tuners, e.g. stepper motor, pneumatic, water flow, etc. A common hardware platform with design choices such as direct sampling of RF, compatible footprint for RF components (e.g. filters), same form factor PCBs, spare channels (RF, analog and digital) made it a reality. The design later turned out to be very adaptive to unforeseen new requirements as the project moved on. Those include adding an interface to enable and monitor the bias tee high voltage power supply, adding a serial interface to communicate with the tuner servo controller and monitoring a cold cathode gauge for faster interlock response. Most recently FRIB LLRF controller use case is expanded to support the testing of e-gun for the SLAC LCLS-II project which runs at a different RF frequency and uses a piezo tuner. Furthermore we are exploring a solution with this versatile platform to support the upgrade of the K500 cyclotron RF control with a continuous frequency range from 10 to 27 MHz.

Speaker: Shen Zhao (Facility for Rare Isotope Beams)

15:30 Advanced optimization of microwave signal stability in the X band unit of SXFEL injector

In the SXFEL injector, the beam stability achieved superior performance, maintaining fluctuations below 0.01% after passing through four S-band accelerating units. However, the stability deteriorated to 0.02% upon exiting the X-band linearizer. To mitigate this degradation, a series of targeted enhancements were implemented, including an extensive upgrade of the low-level RF system’s front-end electronics and the integration of adaptive modulation techniques for input signal optimization. These measures effectively restored and improved the beam stability, achieving precision levels within 0.01%.

Speaker: Chengcheng Xiao (Shanghai Synchrotron Radiation Facility)

15:30 Advancements in RadiaBeam’s multi-dimensional bunch shape monitor: updated testing results and improvements

The Bunch Shape Monitor (BSM) is a versatile diagnostic device designed to measure longitudinal beam parameters, which are essential for the operation and development of high-intensity linear accelerators. However, these measurements remain challenging for proton and ion beams at non-relativistic energies. RadiaBeam has developed an enhanced BSM prototype with several key innovations to improve performance. These include a focusing field between the wire and entrance slit for improved collection efficiency, a redesigned microwave deflector for enhanced beam linearity, and a moving mechanism enabling both transverse profile and longitudinal measurements. Following the initial tests at the Spallation Neutron Source (SNS) presented last year, this work details updated testing results including characterization and optimization, and additional component improvements based on the beam tests conducted at the SNS facility.

Speaker: Aurora Cecilia Araujo Martinez (RadiaBeam Technologies (United States))

15:30 Advancements on bunch profile measurement of the operational H- beam at the SNS linac usinglaser wire

A laser-wire-based method for a direct measurement of bunch profiles of an operational H- beam has been developed at the SNS. In this talk, we report recent advancements on the bunch profile measurements using a customized picosecond pulsed laser with giga-watt peak power and a user-defined macro-pulse structure. The modified system enables fast and precise tracking of the bunch profiles over both the longitudinal and transverse dimensions of the H- beam at different energy levels. The measurement results on the 1.7-MW neutron production beam at the completion of the recent Proton Power Upgrade (PPU) project will be described.

Speaker: Yun Liu (Oak Ridge National Laboratory)

15:30 Advancing accelerator science through data-intensive research and training

The Liverpool Centre for Doctoral Training in Innovation in Data Intensive Science (LIV.INNO) has made significant progress in applying data-intensive methods to accelerator research. This contribution presents research outcomes from the center with a focus on two key projects.

The first focuses on optimizing 3D imaging for medical and industrial applications, integrating Monte Carlo simulations and advanced collimation techniques to enhance low-dose, portable X-ray systems, with implications for wider accelerator diagnostics. The second lever-ages deep learning models to reconstruct transverse beam distributions at CERN, addressing challenges in image distortion from multimode optical fibers under high-radiation conditions. The results are connected with wider progress made in machine learning and artificial intelligence for particle accelerators. Furthermore, the paper summarizes the outcomes of several key LIV.INNO events: the STFC Summer School on Data Intensive Science, the LIV.INNO 2024 Industry Showcase and the 2025 AI for Innovation Summit.

Speaker: Prof. Carsten Welsch (University of Liverpool)

15:30 An effective method for crossbar-switch interference suppression based on WPT in beam position measurements of HLS II

There are 32 electron beam position processors used for beam position measurement in the storage ring of Hefei Light Source(HLS II), the crossbar-switch(CS) of processors must be operation for RF channels compensation and long-term stability. The turn-by-turn(TBT) and fast acquisition(FA) beam position signals would suffer from the CS interference like harmonics and artifact when the CS is operation. In this paper, an effective method based on wavelet packet transform(WPT) is proposed to suppress the CS interference without distorting actual TBT and FA signal. This method starts with the wavelet packet decomposition of the contaminated TBT signal first, then wavelet coefficients are further processed, and finally the processed coefficients of whole subbands are reconstructed through filter banks to obtain the clean TBT signal. As a result, the relatively slow rate of clean and undistorted fast acquisition(FA) signal is obtained through partial reconstruction. Experiment results with real TBT signals demonstrate the effectiveness of the proposed method, and also show that the proposed method does not distort the actual TBT and FA signal while suppressing the CS interference.

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

15:30 Analysis of noise spectra color on machine learning denoising algorithms

Previous work has shown the efficacy of using machine learning for removal of noise in LLRF signals when operating in an industrial environment. Here we extend the analysis to include different noise power spectra. Specifically we analyze the impact on denoisig when correlated noise power spectra are used. Four different noise spectra are analyzed including red, pink, violet, and blue noise. We demonstrate the ability to remove the noise when trained on only white noise and compare this to results when retraining on different color spectra.

Speaker: Jonathan Edelen (RadiaSoft (United States))

15:30 Application of distributed temperature sensor for fire and cryogenic leak detection in accelerator tunnels

High-energy accelerators like CERN’s Large Hadron Collider (LHC) present hazards characterized by temperature variations such as cryogenic leak or fire. Considering that LHC tunnels are large, underground, and radioactive areas, alternatives to traditional systems are explored to improve hazard detection. CERN is investigating the feasibility of installing a large-scale temperature monitoring system in LHC tunnels using Distributed Temperature Sensor (DTS) technology. Based on optical fibre, such a system would be resistant to the LHC radioactive environment and could detect temperature anomalies associated with both fire and cryogenic leak events. This paper presents ongoing studies and a prototype of DTS equipment in the LHC tunnel installed and tested at the beginning of 2025. This publication evaluates the DTS as a safety enhancement tool for accelerator facilities. The potential improvements brought by installing a DTS in LHC tunnels will also be discussed.

Speaker: Michael Dole (European Organization for Nuclear Research)

15:30 Application of vibration wire pre-alignment technology in particle accelerator engineering construction

The role of large particle accelerators in basic research and applied research is becoming increasingly important. In recent years, which have put forward higher requirements for the accuracy and efficiency of particle accelerator alignment measurement. The vibrating wire pre-alignment system measures the magnetic center position of the magnet through the amplitude information of a beryllium copper wire excited in a magnetic field with alternating current, so as to adjust the four-pole and six-pole magnet of a magnet unit to the magnetic coaxial state based on this wire. This paper mainly describes the scheme design and system development process of the vibrating wire pre-alignment system, and conducts a series of test experiments to prove that the device is stable and reliable and meets the expected accuracy index requirements. This lays a solid technical foundation for the subsequent construction of large-scale particle accelerator projects.

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

15:30 Applications of SNMP and syslog monitoring at the TPS control system

The TPS (Taiwan Photon Source) control system is a critical component of the accelerator and beamline. Since the TPS control system is based on the EPICS framework, which communicates through a network, any failure in the control network may result in communication loss between EPICS IOCs, ultimately affecting accelerator operation. To ensure stability, it is necessary to monitor the network status of the control system. This is achieved by using SNMP and SYSLOG to monitor network con-nected devices. This report describes the system architec-ture and implementation details, focusing on how to integrate these technologies to ensure the stable opera-tion of the TPS accelerator control system.

Speaker: Lin-Pin Hsu (National Synchrotron Radiation Research Center)

15:30 Automated control and monitoring system for the Crocker Nuclear Laboratory cyclotron

The Crocker Nuclear Laboratory at UC Davis operates a 72-inch isochronous cyclotron capable of accelerating protons, deuterons, and alpha particles to variable energies up to a maximum of 67.5 MeV for protons. The cyclotron is primarily used for proton therapy, conducting radiation effects testing, and supporting academic research. We describe the upgrade of its original analog control system to a modern digital system capable of integrating AI-based control. This upgrade involves new hardware and software infrastructure to manage subsystems such as the ion beam source, isochronous magnetic field, beam extraction, and beam transport lines. The integrated monitoring and actuator systems are currently being implemented and validated, featuring real-time visualization, a database, and a web application. The new system aims to enhance operations through improved data visualization, database accessibility, and the implementation of autonomous AI-based control, incorporating techniques like artificial neural networks for anomaly detection and automated tuning for efficiency. This document details the hardware and software architecture of the PLC-LabVIEW-Python AI-based control system.

Speaker: Claudio Lopez Osses (Crocker Nuclear Lab)

15:30 Automatic online optimization at the SXFEL facility

The commissioning phase of short-wavelength FEL is often lengthy due to the optimization of thousands of control variables. These variables are frequently interdependent and have non-linear correlations with FEL performance, which makes optimization of such a complex system challenging, particularly for soft XFEL. Additionally, FEL inherently suffers from shot-to-shot intensity jitter, which necessitates online optimization in the presence of strong noise. In this study, we report the results of our experiments using an evolutionary strategy algorithm to enhance FEL intensity despite large intensity jitter.

Speaker: Nanshun Huang (Shanghai Zhangjiang Laboratory)

15:30 Automation of sample alignment for neutron beamlines

Neutron scattering experiments are a critical tool for the exploration of molecular structure in compounds. The TOPAZ single crystal diffractometer at the Spallation Neutron Source and the Powder Diffractometer at the High Flux Isotope Reactor study these samples by illuminating them with different energy neutron beams and recording the scattered neutrons. Aligning and maintaining the alignment of the sample during an experiment is key to ensuring high quality data are collected. At present this process is performed manually by beamline scientists. RadiaSoft in collaboration with the beamline scientists and engineers at ORNL has developed a machine learning based alignment software automating this process. We utilize a fully-connected convolutional neural network configured in a U-net architecture to identify the sample center of mass. We then move the sample using a custom python-based EPICS IOC interfaced with the motors. In this poster we provide an overview of our machine learning tools and show our results aligning samples at ORNL.

Speaker: Jonathan Edelen (RadiaSoft (United States))

15:30 Auxiliary tools for TPS operation

This article provides an overview of various software tools developed by operators to enhance TPS operations. The primary functionalities of these tools include real-time monitoring and notification of light source statuses, as well as data analysis. The tools covered include the TPS alarm system, LINE notification system, real-time orbit deviation display, real-time fast corrector output display, pulse magnet waveform recording and analysis, parameter value changelog, and tools for comparing power supply readings, eBPMs, ID gaps, and XBPM differences between different time points. Each of these tools will be explained in detail throughout the article.

Speaker: Tsung-Yu Lee (National Synchrotron Radiation Research Center)

15:30 Availability assurance in the future circular electron-positron collider (FCC-ee)

The Future Circular Electron-Positron Collider (FCC-ee) is CERN’s leading proposal for the next generation of energy-frontier particle accelerators. At 91 km long, it is ambitious in size, complexity and technical objectives. Availability is a main challenge. This paper presents results from a Monte Carlo simulation that extrapolates reliability and maintain-ability from systems in current working accelerators to the FCC-ee. Significant integrated luminosity shortfall appears in all energy modes due to low availability and operational efficiency. The primary contributors are highlighted, exposing several compelling R&D opportunities.

Speaker: Dr Daniel Wollmann (European Organization for Nuclear Research)

15:30 Beam instrumentation at the multi-turn linac passages of MESA

We will present the status of the beam instrumentation at MESA. To put MESA into operation various diagnostic systems are necessary. To optimize the beam the position and phase with respect to the accelerating RF needs to be optimized to be able to recirculate the beam for multi-turn operation or ERL mode respectively. On the other hand, an absolute beam current measurement is necessary. This can be achieved with a DCCT on the linac axis. The instrumentation will be installed very close to our cryo modules and needs to fulfil the excellent vacuum requirements for superconducting RF.

Speaker: Marco Dehn (Johannes Gutenberg University Mainz)

15:30 Beam profile monitor using thin gas sheets

Transverse beam profile diagnostics for high intensity beams are very challenging as material inserts are untenable. An alternative single shot beam diagnostic was studied, and developed, that consists of a thin sheet of gas. When a charged particle beam traverses the gas sheet, the neutral particles are ionized. The ionization products are then imaged on a monitor and the time of flight is recorded. Based on the specific ionization mechanism at play, the transverse beam profile of the beam can be reconstructed. An experiment at low beam energy was performed at UCLA, and demonstrated the basic concept for impact ionization. Future steps include demonstrating the concept for higher intensity beams as well as technical system modifications to improve the utility in large scale facilities.

Speaker: Gerard Andonian (University of California, Los Angeles)

15:30 Characterisation of the foreseen turn-by-turn beam position instrumentation for the cSTART storage ring

The KIT cSTART project (compact storage ring for accelerator research and technology) aims to demonstrate injection and storage of a high intensity ultra-short bunch using the FLUTE LINAC, as well as a laser-plasma accelerator (LPA).
cSTART is planned to operate with a wide range of demanding parameters, such as bunch charge, bunch length and energy spread (from the LPA), making it extremely challenging for the choice of beam diagnostics with large dynamic ranges that are capable of operating within specifications.
Moreover, turn by turn measurements are necessary in the cSTART storage ring as bunch characteristics are expected to dramatically change within a single turn.
In this paper, we will describe the planned beam diagnostics system of the cSTART storage ring focusing on the turn-by-turn signal processing and reporting on characterization tests which were performed.

Speaker: Anton Malygin (Karlsruhe Institute of Technology)

15:30 Comparison of various outgassing rate measurements for UHV systems

Outgassing rate is one of the most important criteria for vacuum acceptance of various components used in ultra-high vacuum (UHV) systems. There are numerous methods to measure the outgassing rate of UHV components. One of the most common techniques is the so called ‘pressure-rise’ method. In this method the component under test is enclosed in a system and disconnected from the pump. The outgassing rate is calculated from the pressure rise that occurs due to the outgassing of the component. Comparing this with other techniques, the pressure-rise method is more straightforward and allows easier analysis of the data. Nevertheless, the outgassing rate obtained from the pressure-rise method tends to be much lower than the actual outgassing rate. This paper presents an investigation of another approach to analysing the data obtained from the pressure-rise method. The objective of this approach is to provide a greater accuracy in the outgassing rate measurement, as well as to understand the reason behind the large error obtained using the pressure-rise method. The new approach of calculating the outgassing rate from the ‘pressure-rise’ method is then compared to other methods.

Speaker: Phe Suherman (GSI Helmholtz Centre for Heavy Ion Research)

15:30 Considerations for the transverse feedback system for the CERN FCC-ee collider ring

The FCC-ee, a 90.7 km circumference e+ and e- collider under study at CERN, will require a transverse feedback system capable of handling risetimes as fast as four turns for the lowest order coupled-bunch modes. This can be realized by a distributed system of pick-ups and kickers in more than one location of the ring. The advantages are weighed with respect to the flexibility to respond to different choices of transverse tune working points and the possibility to operate the transverse kickers as an exciter for several measurement applications including as a depolarizer for energy calibration at Z and W energies. Options for the signal processing are outlined together with the overall specifications for the system components. The choice of frequency, a multiple of 40 MHz, is determined by requirements of the baseline 25 ns bunch spacing and the desire for a power efficient kicker system favoring stripline kickers. Performance of different variants of the system are compared in simulation and evaluated for added flexibility and complexity with respect to the placement in the ring.

Speaker: Mr Leonard Thiele (University of Rostock, European Organization for Nuclear Research)

15:30 Consolidation of personnel safety systems at CERN

Personnel Safety Systems provide prevention and mitigation barriers to protect personnel, users, equipment, and the environment against the risks associated with the operation of the CERN Accelerators and Experiments, such as Radiation, Fire, Gas and Oxygen Deficiency Hazards. Due to the obsolescence or ageing of technology, evolutions of the facility and the Safety rules, it is now time to consolidate existing safety systems to prepare the CERN complex for the coming decades. A dedicated program has therefore been launched to refurbish the Fire, Gas and Oxygen Deficiency Hazard Detection Systems, and to implement a new Voice Alarm and Evacuation System in the Large Hadron Collider, among others.
The paper provides insight into the methodology used to define the appropriate safety levels required to pragmatically ensure the Safety of personnel and the environment in the facility. Lessons learned from 20 years of operation, interpretation of the legal framework, and the process of risk definition and reduction through preventive and protection measures will be discussed. The main ongoing projects and the challenges ahead of the teams in charge will also be briefly presented.

Speaker: Michael Dole (European Organization for Nuclear Research)

15:30 Cryogenic inserts in the room temperature synchrotron SIS18 at GSI

The existing room temperature heavy ion synchrotron SIS18 at GSI will be used as booster for the future SIS100 at FAIR. One of its features the the generation of high intensity heavy ion beams. In order to create such beams, medium charge states are used, which have a lower space charge limit and can be created with less stripping losses. Unfortunately, such heavy ions have very high ionization cross sections in collisions with residual gas particles, yielding in beam loss and subsequent pressure rises via ion impact stimulated gas desorption. Although an extensive upgrade plan, including NEG-coated magnet chambers and an ion-catcher system, has been realized, the required intesity goals will not yet be reached. Simulations including cryogenic surfaces around the ion catchers show, that their high sticking probability prevents from pressure built-ups during operation. A prototype ion catcher, including such cryogenic surfaces cooled by a commercial cold-head has been developed, built, and tested. It has recently been installed in SIS18 and will undergo further tests, including measurements with heavy ion beams. Findings for the operation and further cryogenic inserts are presented.

Speaker: Lars Bozyk (GSI Helmholtz Centre for Heavy Ion Research)

15:30 Daily performance variations of the LCLS-II super conducting accelerator

Starting with user delivery it was noticed that the FEL intensity performance varied by up to a factor of two during the day. Three injector RF phases for the laser, the gun, and the buncher were not stabilized with a forward and reversed reference signals like the rest of the RF feeding the Cryo-Modules, making them the prime candidates for daily phase drifts. Combining the signals in hardware, firmware and software and temperature stabilizing critical RF cables improved the situation. Additionally, how downstream beam parameters like energy, bunch length, and orbits respond to phase changes of laser, gun, and buncher were quantified, so that the observed daily changes could be attributed to the most likely combination of still uncorrected phase drifts. A feed-forward system similar to the RF of the copper linac using the local temperature was developed to compensate for the remaining changes. Longitudinal feedbacks should see minimal amounts for intervention.

Speaker: Yuantao Ding (SLAC National Accelerator Laboratory)

15:30 Damping of quadrupole oscillations with bunch-by-bunch longitudinal RF feedback for FAIR

To damp undesired longitudinal oscillations of bunched beams, the main synchrotron SIS100 of FAIR (Facility for Antiproton and Ion Research) will be equipped with a bunch-by-bunch longitudinal feedback (LFB) system. It will consist of new broadband kicker cavities and a dedicated low-level RF (LLRF) system. The LFB helps to stabilize the beam, to keep longitudinal emittance blow-up low and to minimize beam losses via damping dipole and quadrupole oscillations for up to 10 bunches individually. The topology of the LLRF signal processing is validated in closed loop with beam in the heavy-ion synchrotron SIS18 at GSI for future integration into SIS100. In a recent SIS18 machine development experiment with two bunches at flattop, quadrupole oscillations were excited for one bunch and then damped with a prototype setup of the LFB system using an existing magnetic alloy cavity as dedicated kicker cavity. This paper presents the test setup, the results of this experiment, and the proposed LLRF topology of the closed-loop LFB system. This validates a core part of the final SIS100 system.

Speaker: Dieter Lens (GSI Helmholtz Centre for Heavy Ion Research)

15:30 Design and commissioning of BRing vacuum system

The Booster Ring (BRing), which requires an average vacuum to be better than the 10-10Pa，is the key part of the High Intensity Heavy Ion Accelerator Facility. The total length of BRing is 569.0985 meters, the characteristics of long circumference, large cross-section and a large amount of gas load, pose great challenges for on-site installation and achieving the vacuum index. Therefore, optimization has been carried out from several aspects. Firstly, in order to reduce eddy current, 0.3mm thick low permeability stainless steel is required. Different from the commonly used ceramic vacuum chamber or 0.3mm thin-walled chamber with ribs, the structure of placing high-strength, low gas load inner lining skeleton at intervals inside the 0.3mm thin-walled chamber is proposed for the first time. Using 3D printing technology to process the inner lining skeleton and coating it with getter film to reduce the pressure gradient. Secondly, the kicker chambers are equipped with ferrite, which brings high gas load. So a process for reducing the outgassing rate of ferrite has been explored, which can make the outgassing rate of ferrite ≤ 1.125×10-9Pa.L.S-1.cm-2. After testing, the vacuum of the kicker chamber is better than 7×10-10Pa. Thirdly, the pressure distribution of BRing was calculated by Molflow software, and the pumping scheme has been optimized. The BRing vacuum system has been installed, and the entire ring has undergone on-site baking, with an average vacuum better than 7×10-10Pa.

Speaker: wenjun Xie (Institute of Modern Physics, Chinese Academy of Sciences)

15:30 Design and development of AR RF personnel protection and interlock system for RF Test with Access mode to RF cavities in ALS-U project at LBNL

The ALS-U project at LBNL is a major upgrade of the ALS involving a new Accumulator Ring (AR) and an upgraded Storage Ring (SR). The new AR RF System has one operational mode with beam and three test modes without beam. Another upgraded overarching Ring Personnel Protection Systems (PPS) covering both AR and SR ring enclosure areas is in place for personnel protection from ionizing radiation during beam operation and it is interfaced with AR RF PPS subsystem for status & control signals. In the RF Test with Access mode, the controlled access of authorized personnel is permitted to AR RF cavities area when it is powered below certain predetermined power limit without beam, for conducting low power RF leakage checks, tests. For that objective, an AR RF PPS power monitor & interlocks as described in this paper has been designed & developed for use in the Test with Access mode in order to ensure that potential exposure to harmful ionizing X-rays from RF cavity operating does not result in doses above the prescribed limits. The actual X ray dose rate data will also be experimentally surveyed at various RF cavity power levels. This paper presents the design features, circuits and construction of such AR RF PPS subsystem for accurately monitoring RF Cavity power and to break the interlocked chain to turn OFF the RF input drive to AR RF High Power Amplifiers (HPA) feeding RF cavities, if the RF cavity power exceeds such pre-determined power limits.

Speaker: Shree Subhasish Basak (Lawrence Berkeley National Laboratory)

15:30 Design and implementation of control system for chopper and kicker in HIAF

As important parts of the High Intensity Heavy Ion Accelerator Facility(HIAF), the Chopper and the Kicker play an indispensable role in controlling the operation mode of the beam and the protection of the machine. Accurate timing control is the key technical requirement and difficulty of this type of equipment, and it has a profound impact on the injection and extraction efficiency and beam quality of HIAF.
According to the physical requirements of HIAF, this paper studies the distributed control technology of Chopper and Kicker systems, and proposes a design scheme of a general hardware platform for timing control of fast pulse devices, which mainly uses White Rabbit high-precision timing, FPGA and optical fiber transmission technology to complete the development of hardware, software and timing system interfaces, and realizes the new design of the core control system and the independent research and development of some core technologies.

Speaker: Pengpeng Wang (Institute of Modern Physics, Chinese Academy of Sciences)

15:30 Design and status of LLRF system for PREF linac

The Proton radiation effects facility (PREF) was designed and constructed by the Institute of Modern Physics, which can provide high-quality proton beams with continuous and accurate tunable energy range, high current intensity, high duty cycle and large scanning area of 10-60MeV energy range. which consists of a proton source, RFQ linac injector, synchrotron and irradiation terminals. The RFQ works at 162.5 MHz, providing 1.2Mev proton beam for synchrotron. The RF system consists of a RFQ cavity, two 50 kW solid state amplifiers and digital low level RF control system (LLRF). The amplitude and phase stability requirements for the LLRF are 1% and ±1°separately. To meet requirements and to ensure reliability, a digital LLRF system was designed. The new digital LLRF is based on Virtex5 FPGA, fast ADCs and DACs, and CPCI bus. The progress and plans for future are presented.

Speaker: Xiaodong Han (Institute of Modern Physics, Chinese Academy of Sciences)

15:30 Design and validation of a micrometric and adaptable calibration bench for frequency scanning interferometry sensors

The High-Luminosity Large Hadron Collider (HL-LHC) project at CERN aims to enhance the LHC's performance and increase its discovery potential. As part of this upgrade, new components will be installed and must be aligned with an accuracy of 0.17 mm vertically and 0.33 mm radially (1σ) over a length of 420 m.
To achieve such requirements in harsh conditions, CERN has developed a range of new sensors using Fourier analysis-based Frequency Scanning Interferometry (FSI), capable of absolute distance measurements on multiple targets within a few micrometers’ uncertainty. More than 600 of these FSI sensors will be deployed for the project, necessitating an accurate, fast, adaptative and cost-effective calibration of these sensors. To do so, a specialized calibration bench has been developed.
This paper details the design, benchmarking, and final validation of this calibration bench, which enables rapid calibration of a wide range of FSI sensors to an accuracy below 10 μm (1σ). Additionally, it presents the first intense use of this bench in the frame of the Inner Triplet String test, a facility representing one complete section of new focusing regions of the HL-LHC upgrade project.

Speaker: Mateusz Sosin (European Organization for Nuclear Research)

15:30 Design of RF duct shielding for the SPS-II 3-GeV electron storage ring

The Siam Photon Source II (SPS-II) is a fourth-generation synchrotron light source designed to provide high-brightness, low-emittance, high-energy electron beams for advanced synchrotron applications. SPS-II is equipped with a 150-MeV linear accelerator, a 3-GeV booster synchrotron, and a 3-GeV electron storage ring, enabling the production of high-quality synchrotron radiation for a wide range of scientific research fields. The 500 MHz RF system in the storage ring serves to replenish the energy lost by electrons due to synchrotron radiation. RF cavities generate oscillating electromagnetic fields at a specific frequency, accelerating the electrons each time they pass through the cavity. The RF ducts house the waveguides and transfer RF power to the RF cavities inside the storage ring tunnel. However, penetration in the storage ring tunnel may allow radiation within the shielding tunnel to leak outside the shielding. For this reason, the design of the RF ducts must be carefully considered. The FLUKA particle transport code is used to investigate the shielding. The results indicate that the radiation dose is below the design criterion, meeting the radiation safety standards.

Speaker: Supachai Prawanta (Synchrotron Light Research Institute)

15:30 Detector protection system used in the Taiwan Photon Source 13A experimental station

At the Taiwan Photon Source 13A experimental station, the detector is prone to noise interference in a vacuum environment ranging from 750 torr to 7 mtorr, which can lead to malfunctions. Therefore, a rapid automatic power-off system has been designed to immediately shut down the detector's power when it is in an abnormal vacuum range, reducing the impact of noise on the detector and thereby extending its lifetime.

Speaker: Chia-Feng Chang (National Synchrotron Radiation Research Center)

15:30 Developing an Object Detector Using Synthetic Data from CAD Models

This work investigates the potential of using synthetic images generated from CAD models to train an object detector for identifying components of a particle accelerator. The study focuses on magnets within the new ALS Accumulator Ring at Lawrence Berkeley National Laboratory. Generating large volumes of real-world training data is often challenging in such complex systems. To address this, CAD files were converted into 3D models and used to produce diverse synthetic datasets. These datasets were augmented with a smaller set of real-world images to train a YOLOv8-based model. This approach aims to evaluate whether synthetic images can effectively support the development of object detectors in environments where real data collection is limited. The study lays the groundwork for future development of real-time recognition tools to assist accelerator operations.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

15:30 Development and testing of an autocorrelator for measuring the duration of picosecond pulses of near infrared radiation

The paper presents a design of an autocorrelator manufactured to measure the duration of infrared picosecond pulses of radiation from the 3rd laser of the Novosibirsk Free Electron Laser facility, as well as the results of testing the autocorrelator when measuring the duration of picosecond pulses in the visible range. The results and future plans for future experiments using developed autocorrelator

Speaker: Vladislav Borin (Russian Academy of Sciences)

15:30 Development of a 500 MHz direct RF sampling low-level RF system for ALBA and ALBA-II

ALBA Low-Level RF (LLRF) system has provided over a decade of reliable operation and has been adopted by other synchrotron facilities. To meet the evolving requirements of ALBA and ALBA-II, a new LLRF system has been developed. This system features FPGA and ADC/DAC MTCA boards designed by SAFRAN, enabling direct 500 MHz signal sampling without down/up-conversion. These enhancements reduce system complexity, minimize noise, and simplify maintenance. SAFRAN also supplies peripheral modules and the Tango device server generator, while ALBA implemented it and developed a new GUI. Upgraded GPIO and RF signal patch panels complement the new hardware. The legacy VHDL code has been updated to improve readability and functionality, incorporating advanced features such as octant selection and a harmonic direct feedback selection method. The latter, based on IIR filtering, isolates positive and negative revolution harmonics in the I/Q domain, feeding them back to amplifiers to effectively mitigate transient beam loading caused by the storage ring bunch train gaps. This upgraded LLRF system delivers enhanced performance and greater flexibility to address the future needs of ALBA and ALBA-II.

Speaker: Francis Perez (ALBA Synchrotron (Spain))

15:30 Development of a customised wrapper for p4p and use of this to migrate ISIS's accelerator controls from Vsystem to EPICS

The controls system for the ISIS accelerator is being migrated from using the commercial software Vsystem to EPICS which is open source. The primary protocol used for transporting process variables (PVs) across the network is pvAccess and the Python-based software p4p is used to create servers that provide access to process variables (PVA servers). A custom wrapper for p4p is being implemented to simplify and standardise way in which PVA servers work. This will allow users to easily create PVA servers for their own devices whilst allowing automatic registration with other services, for example ChannelFinder.
The main device interface used for ISIS accelerator controls is an in-house developed CPS crate and these require a Vsystem reader to initialise and read channels from each CPS crate. This functionality can be replaced using the customised p4p module to provide a service that can initialise the crate and then start a PVA server to provide the PVs for that crate. This will allow decoupling the CPS crates from Vsystem so that they can be moved into EPICS.

Speaker: Ajit Kurup (Imperial College London)

15:30 Development of a flexible digital twin framework for accelerators using design patterns

These days designing an accelerator consist of prototyping and testing adequate commissioning software. Digital twins serve as natural test benches for validating and monitoring the required physics software stack. These twins must align with the current design state of the accelerator from the project's inception to the machine's commissioning. The authors have developed a modern digital twin framework based on software design patterns. Its architecture emphasizes clean design principles with minimal coupling between components. Its setup requires only lattice and device configuration data. Thanks to its design, it seamlessly integrates into prototyping environments or control system infrastructures. In this paper, we briefly describe the design patterns underlying this architecture, highlight the flexibility and advantages of the infrastructure, and outline the steps needed to implement it for a machine currently lacking a digital twin.

Speaker: Waheedullah Sulaiman Khail (Helmholtz-Zentrum Berlin für Materialien und Energie)

15:30 Development of CT monitor to measure the stacking beam current in the FETS-FFA test ring

The FETS-FFA will be a proof-of-principle Fixed Field Alternating gradient accelerator (FFA), to demonstrate the feasibility of these machines to drive megawatt-class spallation neutron sources, such as the proposed ISIS-II. It will accelerate protons from 3 to 12 MeV, and demonstrate high-intensity operation through large space charge tune shift. Beam stacking takes advantage of the static magnetic fields and large momentum acceptance of an FFA, to overcome space-charge intensity limitations by combining beams at their highest energy. Four coasting beams are expected to be stacked over 80 ms, which demands an intensity monitor sensitive to coasting beams over this time. Conventional DC Current Transformer's (DCCT's) have proven difficult to develop for a large aperture, so a single inductive core equipped with a Negative Impedance Converter (NIC) amplifier is being developed to provide a time constant of 1 second. This paper will present a feasibility study of this Current Transformer(CT), as well as bench measurements with a large-aperture FT3M FINEMET core and prototype NIC.

Speaker: Yoshihisa Iwashita (Osaka University)

15:30 Development of low-level RF control system for Injector of Hefei Advanced Light Facility project

Hefei Advanced Light Facility (HALF) is a fourth-generation synchrotron radiation source based on diffraction limited storage ring. It comprises a 180-meter injector and a 480-meter storage ring. The injector incorporates a digital low-level radio frequency (LLRF) control system based on MTCA.4, ensuring a stable and adjustable microwave field for the acceleration structure. This article outlines the structure of the LLRF system, encompassing both hardware and software components. Within the software, we have mitigated signal drift induced by environmental temperature fluctuations by adding a reference tracking module. Building upon the existing IQ closed-loop functionality, we have successfully implemented separate amplitude and phase closed-loop functions. In high-power online testing, the IQ closed-loop demonstrated amplitude and phase stabilities of 0.0411% (RMS)/0.0638° (RMS), respectively. Furthermore, the phase stability achieved by the phase-independent closed-loop function reached 0.0646° (RMS). Currently, the LLRF system has fulfilled the design requirements of HALF.

Speaker: Baiting Du (University of Science and Technology of China)

15:30 Development of metal vacuum chamber with low eddy currents under high frequency magnetic fields

HIAF-BRing, the booster synchronous ring of the High Intensity Heavy-Ion Accelerator Facility, is rapid cycling synchrotron. It requires a vacuum pressure of 5 ×10 -10Pa and a vacuum pipeline that generates small eddy currents under high-frequency magnetic fields of 12 T/s. A new type of vacuum chamber has been successfully developed to reduce effectively the eddy current effect. It also significantly reduces the gap of the dipoles and quadrupoles, compared to the thin-walled stainless steel vacuum chamber with reinforced ribs. The chamber consists of stainless steel pipe with a thickness of 0.3mm and ceramic lining rings. Ceramic rings are gradually and intermittently arranged along the pipeline as a support frame for metal thin-walled chamber. High strength ceramics and stainless steel of the chamber can be baked safely at 300 ℃. Through experimental testing, vacuum pressure of the chamber reaches 4.2 × 10-10pa. The ceramic rings are Au-coated to effectively reduce the beam impedance and the desorption rate of ceramic materials.

Speaker: Weishun Yang (Institute of Modern Physics, Chinese Academy of Sciences)

15:30 Development of new MADOCA control system for SPring-8-II

The MADOCA control system was developed for the present SPring-8 in 1997. Nowadays we faced problems of outdated technologies of the MADOCA. In 2025, SPring-8 upgrade project "SPring-8-II" will be started. Toward to the SPring-8-II, we decided to renovate the MADOCA control system. The new control system inherits former MADOCA's concepts, which are characterized by SVOC-style messaging, database-oriented framework, and distributed control design using network system. In contrast with the inherited concepts, we renew the base technologies. Upgrades of messaging platform, data acquisition, and databases are already reported.*,** We continue to develop other components. For edge computing, we use both MicroTCA.4 and generic PC server instead of outdated VME system. By combining EtherCAT with these edge computers, we support various I/O interfaces with simple wiring. We also provide REST API as database reading method to support external system linkage. Prior to the SPring-8-II project, the new control system is introduced into NanoTerasu. In this paper, we report the latest developments and prospective of the new control system.

Speaker: Dr Takashi Sugimoto (Japan Synchrotron Radiation Research Institute)

15:30 Development progress of high-level applications for the HEPS

To meet the beam commissioning requirements of the High Energy Photon Source (HEPS), a brand-new framework called Pyapas was developed using pure Python. All high-level applications (HLAs) for the HEPS are being built upon this framework. The beam commissioning of the Linac started on March 9, 2023, and the HLAs performed excellently, helping the Linac to successfully complete the test and acceptance. By mid-2023, the development of all HLAs for the booster was successfully completed, paving the way for beam commissioning, which began in late July and concluded with in its successful acceptance in November 2023. By June 2024, the development of HLAs for storage ring was completed, followed by multiple rounds of offline testing iterations and joint tests with the hardware system. 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. This paper provides a comprehensive review of the recent progress in the development of HEPS HLAs, emphasizing milestones achieved during the booster and storage ring commissioning, and outlines the roadmap for future development.

Speaker: Xiaohan Lu (Institute of High Energy Physics)

15:30 Early prediction of system failures at Los Alamos Nuclear Science Center

Accelerators are complex systems composed of tens of thousands of individual components requiring continuous maintenance. Aging facilities such as LANSCE face an increased rate of equipment failures, resulting in costly unscheduled shutdowns for maintenance. Early identification and localization of problems along the accelerator can mitigate future failures during scheduled maintenance periods rather than emergency shutdowns. This approach will significantly enhance the facility's reliability and increase beam availability for users. We have developed a mathematical formalism to analyze all available data for a LANSCE subsystem and generate signals indicating abnormal operation. The system accounts for hidden internal correlations between various parameters. This predicted deviation from the norm is supported by historical records in log files. We report progress on developing an anomaly detection system for LANSCE by expanding predictions to all subsystems, increase LANSCE's data archiving capability by an order of magnitude, and developing algorithms to provide operators with signals indicating developing abnormalities and pinpointing problematic beamline elements.

Speaker: Nikolai Yampolsky (Los Alamos National Laboratory)

15:30 Electromagnetic compatibility and spurious triggering detection validation of the CLIQ units for superconducting magnet protection in the High-Luminosity LHC project

The Coupling-Loss-Induced-Quench (CLIQ) concept is an integral part of the quench protection system for the High-Luminosity Large Hadron Collider (HL-LHC) Inner Triplet superconducting magnets at CERN. Since the discharge of the CLIQ unit induces a change of the magnetic field in the low beta quadrupoles, a spurious trigger during operation could deflect the beam, potentially causing critical losses and posing a failure risk for the LHC. To ensure reliable and faultless operation and to prove that the units are immune to potential interferences capable of provoking an erratic trigger, several qualification tests were performed, including interference tests with actual LHC equipment and standard Electromagnetic Compatibility (EMC) tests. Furthermore, the precision of the CLIQ monitoring sensors was validated to confirm that, in the unlikely event of a spurious trigger, the particle beam could be dumped in time to prevent damage. The final CLIQ units, with enhanced redundancy, monitoring and safety measures, and robust EMC design, have been completed. This paper details the conducted EMC tests, confirming their resistance to erratic triggers and ability to timely request beam dumps.

Speaker: Dr David Carrillo (European Organization for Nuclear Research)

15:30 eLog analysis for accelerators: status and future outlook

This work demonstrates electronic logbook (eLog) systems leveraging modern AI-driven information retrieval capabilities at the accelerator facilities of Fermilab, Jefferson Lab, Lawrence Berkeley National Laboratory (LBNL), SLAC National Accelerator Laboratory. We evaluate contemporary tools and methodologies for information retrieval with Retrieval Augmented Generation (RAGs), focusing on operational insights and integration with existing accelerator control systems.

The study addresses challenges and proposes solutions for state-of-the-art eLog analysis through practical implementations, demonstrating applications and limitations.
We present a framework for enhancing accelerator facility operations through improved information accessibility and knowledge management, which could potentially lead to more efficient operations.

Speaker: Thorsten Hellert (Lawrence Berkeley National Laboratory)

15:30 Enabling arbitrary correlations in beam phase space via curve matching

Beam manipulations require precise control of phase space correlations. Gwanghui's previous work introduced a method for generating arbitrary correlations using Fourier series and cosine sums with transverse wigglers. However, accurately controlling the wigglers to match a desired correlation curve remains challenging, as it involves optimizing parameters like amplitude, phase, and period. Existing optimization methods are computationally intensive and prone to local minima.
We address these limitations with a deterministic gradient-based optimization process. Using a differentiable error function, we efficiently perform gradient backpropagation to identify optimal parameters. To minimize the number of wigglers while maintaining accuracy, we adopt a recursive strategy: starting with a single wiggler and iteratively adding one at a time, using results from prior steps as seeds. This approach accelerates optimization and reduces computational demands.
Building on this method, we design a feedback control strategy for real-time correlation generation with transverse wigglers, enabling precise, flexible beam manipulation and new possibilities in accelerator physics.

Speaker: Alex DeSimone (Northern Illinois University)

15:30 Enhancing quench detection in SRF cavities at the EuXFEL: Towards machine learning approaches and practical challenges

Detecting anomalies in superconducting cavities at the EuXFEL is essential for reliable operation. We began with a model-based anomaly detection approach focused on residual analysis. To improve fault discrimination, particularly for quench events, we augmented the detection with a machine learning-based classification. Key challenges are posed by the transition to real-time operation, requiring computational and integration adjustments. For the online application, we deployed two servers at one of the 25 stations to detect and log anomalies with a software implementation. In parallel, we pushed the development of a firmware solution that will counteract critical faults in real-time. At the current stage only the anomaly detection is in online operation, which is planned to be augmented with the online fault classification in the future. The resulting detection system delivers reports across various timescales, supporting both immediate responses and long-term maintenance.

Speaker: Nadeem Shehzad (Deutsches Elektronen-Synchrotron DESY)

15:30 Evaluation of an X-band LLRF prototype for the EuPRAXIA@SPARC_LAB LINAC

EuPRAXIA, the "European Plasma Research Accelerator with eXcellence In Applications," represents the next generation of free-electron lasers (FEL). It aims to develop a compact, cost-efficient particle accelerator using innovative wake-field accelerator technology. High-energy physics often demands higher acceleration voltages, and X-band technology offers high gradients in compact structures. The EuPRAXIA@SPARC_LAB LINAC injector, featuring an S-band RF gun, four S-band structures, and sixteen X-band structures, achieves a maximum beam energy of 1 GeV. For femtosecond-level synchronization and stability, Low-Level Radio Frequency (LLRF) systems are essential. However, commercial X-band LLRF solutions are unavailable. This project, in context of the EuPRAXIA - Doctoral Network, develops an X-band LLRF prototype tailored to meet the EuPRAXIA@SPARC_LAB LINAC's stringent requirements. After validation on a testbench, the prototype will enable industrial production and commercialization. This paper presents the Front-End, Back-End analysis, and further evaluation of the prototype.

Speaker: Phani Deep Meruga (Instrumentation Technologies (Slovenia))

15:30 Experience with the CERN LINAC4 and its performance during the first four years of operation

Since 2020 LINAC4 provides the protons for the entire CERN accelerator complex. It accelerates H- ions to a kinetic energy of 160 MeV and injects them into the Proton Synchrotron (PS) Booster using a charge exchange injection mechanism. The performance requirements have been successfully met since 2021. This paper presents the operational experience gained, together with availability and reliability statistics for LINAC4, during its first four years of operation, and details the key performance indicators for beam quality and stability. It also discusses the main issues encountered and the implemented solutions that have allowed further improvements to be made. Recent developments on the H- ion source have led to an increase of the beam current from the original 35 mA to 50 mA, opening the possibility to increase the intensity delivered to the PS Booster for the benefit of CERN's experimental programmes. Beam energy modulation in LINAC4 has also been developed to increase the PS Booster bunch intensity for which the results of beam tests are presented.

Speaker: Piotr Skowronski (European Organization for Nuclear Research)

15:30 FGC Test Manager: A framework for executing and monitoring software tests

Function Generator Controllers (FGCs) are key devices used in CERN’s converter control systems to regulate and monitor the power converters that supply current to the magnets in the accelerator complex. To ensure the reliability and enhance the quality assurance of the software that controls these devices, the FGC Test Manager has been developed. It encompasses the Python library pyfgc_test_framework, which provides an interface for test scripts to seamlessly communicate with the FGC devices; and a web tool providing an interface to run test scripts on schedule and on demand, assign tests to resources, review test results, and directly access test logs. The web tool uses Vue 3 for the frontend and FastAPI with a PostgreSQL database for the backend. Test execution is handled by the GitLab Pipeline API, which executes pipelines directly in the repository containing the tests. This paper presents the design and functionality of the FGC Test Manager and the improvements it brings to the quality assurance of CERN's converter control systems.

Speaker: Franziska von Albedyll (European Organization for Nuclear Research)

15:30 First cryogenics operational experience of the ESS cryomodules in LINAC configuration

This paper presents the first operational experience of the European Spallation Source (ESS) cryomodules in a linac configuration, with a focus on the challenges encountered during the initial integrated cooldown and subsequent stable operation. Key aspects such as thermal stability, cryogenic performance, and system integration are discussed in detail. The paper also highlights lessons learned during the operation, identifies areas for improvement, and proposes strategies for optimizing cryogenic operations in the upcoming phases of the ESS project.

Speaker: Nuno Elias (European Spallation Source)

15:30 First prototype measurements with an electro-optical bunch profile monitor for FCC-ee

The future circular electron-positron collider (FCC-ee) is designed for highest luminosity to enhance the precision of high-energy particle physics experiments, spanning energies from the Z pole to the $\text{t}\bar{\text{t}}$ threshold. As outlined in its conceptual design report, high-precision measurements of the longitudinal bunch profile are required across multiple operation modes, which presents key challenges for beam instrumentation. As part of the feasibility study, a concept for an electro-optical (EO) bunch profile monitor has been developed to address these challenges, building on the existing EO beam diagnostic at the Karlsruhe Research Accelerator (KARA) at KIT. The first EO monitor prototype for FCC-ee features a novel crystal-holder design using prisms, enabling a single-pass setup crucial for measuring the long bunches during Z operation.
This contribution presents the first measurement results of the EO monitor prototype for FCC-ee, which were obtained in the in-air test stand at the CERN Linear Electron Accelerator for Research (CLEAR).

Speaker: Micha Reissig (Karlsruhe Institute of Technology)

15:30 FPGA-based multi-precision RF waveform measurement

RF measurements are crucial for stabilizing the power source output and extracting beam data. As digital systems evolve, the analog-to-digital converter (ADC) now commonly reaches 16 bits and 100 MHz, enabling multi-channel low-level radio frequency (LLRF) systems to generate several gigabytes of data per second, overwhelming data storage and processing capabilities. This paper proposes a pre-processing method using Field Programmable Gate Arrays (FPGAs), which dynamically adjusts timing intervals based on operator requirements. For detailed waveform analysis, the LLRF can upload data over short time intervals with high precision. Conversely, for applications concerned with slow drift, long-time-range, low-precision data is transmitted. Thus, the total amount of uploaded data remains constant. A multi-order filter is applied to the raw data, with desired precision achieved at specific orders. The time precision ranges from 10 ns to 20 µs, while the time range spans from 20 µs to 40 ms.

Speaker: Yiming Xu (Shanghai Synchrotron Radiation Facility)

15:30 Fully experiment request driven beta* and separation luminosity levelling at the LHC

During the third run period (2022-2026) of the CERN Large Hadron Collider (LHC), as well as for the future High-Luminosity LHC era, luminosity levelling is key to control the event pile-up in the experiments as well as the heat load to the cryogenic system of the superconducting magnets close to the interaction points. During 2024 proton physics operation, a new luminosity levelling scheme was introduced for the high-luminosity experiments, ATLAS and CMS. Combining levelling by optical squeeze (beta) with small transverse separation changes gives the beam stability benefits of beta levelling (head-on tune spread and landau damping) while keeping the flexibility of separation levelling (independent levelling for each experiment in arbitrary steps of luminosity). This not only allowed each experiment to set their luminosity target independently, but also reduced the luminosity spread during levelling from 5%, when using just beta* levelling, to less than 3%, resulting in a more homogeneous data set.

Speaker: Michi Hostettler (European Organization for Nuclear Research)

15:30 Genetic algorithm code for real-time optimization in the STAR thomson back-scattering source

The STAR facility represents an advanced high-energy photon source located at the University of Calabria (Italy). It was conceived to generate high-energy photons through the inverse Thomson scattering process. Following a recent upgrade, the facility features an additional beamline driving the source from 65 MeV electron beam energy up to 140 MeV, leading to a maximum photon energy of 350 keV. The control system based on the EPICS framework is central to STAR's operation. Optimizing the machine's performance requires advanced methodologies capable of managing its non-linear dynamics. Artificial intelligence, particularly Genetic Algorithms, has emerged as a powerful tool for achieving real-time optimization. The software GIOTTO, a GA-based optimization framework, will be set to redefine STAR's beamline operations by dynamically tuning machine parameters to enhance radiation production and beam quality. By driving the ASTRA simulation code as a stand-in for the real machine, we are actively testing GIOTTO's capabilities in a controlled environment. The full integration of GIOTTO into STAR's control system promises to improve the machine and beam dynamics optimization processes.

Speaker: Antonietta Olivieri (Sapienza University of Rome)

15:30 High precision RF pulse shaping with direct RF sampling for future linear accelerators

In various of particle accelerator designs, amplitude and phase modulation methods are commonly applied to shape the RF pulses for implementing pulse compressors or compensating for the fluctuations introduced by the high-power RF components and beam loading effects. The phase modulations are typically implemented with additional phase shifters that requires drive or control electronics. With our recent next generation LLRF (NG-LLRF) platform developed based on the direct RF sampling technology of RF system-on-chip (RFSoC) devices, the RF pulse shaping can be realized without the analogue phase shifters, which can significantly simplify the system architecture. We performed a range of high-power experiments in C-band for evaluating the RF pulse shaping capabilities of the NG-LLRF system at different stages of the RF circuits. In this paper, the high-power characterization results with the Cool Copper Collider structure driven by RF pulses with different modulation schemes will be described. With the pulse modulation and demodulation completely implemented in digital domain, the RF pulse shaping schemes can be rapidly adapted for X-band structures just by adding analogue mixers.

Speaker: Ankur Dhar (SLAC National Accelerator Laboratory)

15:30 High-dimensional single-shot optical field compressive diagnostic

Laser field diagnostic has long been limited by dimensions of obtained information and one-shot measurement ability. The term “dimension” refers to spatiotemporal distributions, but also physical quantities completely defining a light field including amplitude, phase and polarization. Conventional diagnostic systems realize multi-shot or incomplete measurements of laser optical field, but are limited to characterize actual low-repetition, complex “structured” laser fields. A full characterization of spatiotemporal quantities of light field is essential, as the accelerated electron bunch distributions and qualities are highly dependent on the incident complex laser. A full characterization of complex structured light fields will be a potential tool for the single shot, high dimensional electron bunch diagnostic. Here we proposed the technique of high-dimensional single-shot optical field diagnostic, resolving full-dimensional information of arbitrary spatiotemporal inhomogeneous laser fields. It is believed that this novel light detection technique can not only be further compactly implemented for pre-diagnostic of electron acceleration, but also observe 3D electron bunch dynamics.

Speaker: Yaodan Hu (Huazhong University of Science and Technology)

15:30 Impact of beam background and jitter on LUXE interaction point

LUXE is an international project that aims to study Quantum Electro-Dynamics processes that occur in the strong field regime. Using the electron beam from the European XFEL, this experiment will perform electron-laser and photon-laser collisions. Beamline simulations are required to understand what beam properties and backgrounds are expected at key locations. The beam optics was design and simulated with MAD-8 and this used to create a BDSIM simulation. To perform high precision interactions it is crucial that the transverse size and position of the electron beam can be measured. The variation of the beam position over time also has impacts on an efficient collision with the laser. This study uses simulated virtual measurement, wire scanning methods, and real measurements at the XFEL to evaluate those parameters. Finally, background from both the upstream beam line and the different dumps must be estimated to ensure that the impacts on the experiment are low enough. This paper present BDSIM simulations with high statistics necessary to evaluate the background. Critical for BDSIM studies is finding optimised ways to do cross-section biasing and final state splitting in the dumps.

Speakers: Marin Deniaud (Cockcroft Institute), Stewart Boogert (Cockcroft Institute)

15:30 Impact of beam energy increase on the dose rates in and around SNS service bay

The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) is an accelerator-based neutron source facility that provides the most intense pulsed neutron beams in the world for scientific research and industrial development. The neutron production occurs when a horizontally injected proton beam strikes the liquid mercury target placed in the center of the target monolith. The mercury target has a finite lifespan due to radiation and cavitation damage, and therefore is mounted on a carriage that can be retracted for replacement into the target service bay located at the back of the target monolith. The Proton Power Upgrade Project (PPU), which will double the accelerator power capability from 1.4 to 2.8 MW and will increase the proton beam energy from 1 GeV to 1.3 GeV, is completed. To evaluate the impact of the proton energy increase on radiation safety, neutronics studies are performed to characterize the dose rates inside and outside the SNS service bay. Studies are conducted for the incoming proton beam at 1 GeV and 1.3 GeV.Analyses of the dose rates show thatvthe target service bay shielding works adequately providing dose rates below facility limits.

Speaker: Irina Popova (Oak Ridge National Laboratory)

15:30 Implementation and evaluation of bunch-by-bunch feedback systems at PLS-II for coupled-bunch instability mitigation

In synchrotron light sources, coupled-bunch instabilities driven by resonant wakefields in the vacuum chamber pose significant challenges to beam stability and quality. This study presents the implementation and evaluation of a bunch-by-bunch feedback system at the Pohang Light Source-II (PLS-II). Utilizing state-of-the-art feedback technologies, including Dimtel iGp12 baseband processors and advanced BPM hybrid networks, the system was configured to address both transverse and longitudinal instabilities. Key demonstrations include real-time grow/damp measurements, fast tune tracking, and bunch cleaning to suppress unstable modes effectively. Comparative analysis with the SPring-8 feedback system highlights performance improvements and system tuning strategies tailored to PLS-II’s operational parameters. Results from horizontal and vertical plane modal amplitudes demonstrate robust damping capabilities, maintaining beam stability even at high currents and narrow insertion device gaps. These advancements contribute to enhanced operational efficiency and higher quality photon output at PLS-II.

Speaker: Si-Won Jang (Pohang Accelerator Laboratory)

15:30 Implementation of EPU66S control system at the Taiwan Photon Source

The EPU66S, an elliptically polarized undulator with a 66 mm period, is a component of the Phase III beamline project at the Taiwan Photon Source (TPS). It was successfully installed in the TPS storage ring in January 2025. The control system for the EPU66S is developed within the EPICS framework, integrating motion controllers and EtherCAT communication. This system also includes a safety interlock mechanism, which halts motion in response to limit switches, torque limit switches, emergency stop button, and linear optical encoder feedback. To ensure smooth operational testing, all hardware and software components of the
EPU66S control system were fully integrated prior to installation. This paper presents the development process of the EPU66S control system, with a focus on the optimization of its motion control test platform.

Speaker: Zi.Qi Wu (National Synchrotron Radiation Research Center)

15:30 Integrated denoising for improved stabilization of RF cavities

Typical operational environments for industrial particle accelerators are less controlled than those of research accelerators. This leads to increased levels of noise in electronic systems, including radio frequency (RF) systems, which make control and optimization more difficult. This is compounded by the fact that industrial accelerators are mass-produced with less attention paid to performance optimization. However, growing demand for accelerator-based cancer treatments, imaging, and sterilization in medical and agricultural settings requires improved signal processing to take full advantage of available hardware and increase the margin of deployment for industrial systems. In order to improve the utility of RF accelerators for industrial applications we have developed methods for removing noise from RF signals and characterized these methods in a variety of contexts. Here we expand on this work by integrating denoising with pulse-to-pulse stabilization algorithms. In this poster we provide an overview of our noise reduction results and the performance of pulse-to-pulse feedback with integrated ML based denoising.

Speaker: Jonathan Edelen (RadiaSoft (United States))

15:30 Integrating community codes for accelerator design and optimization

Advances in fidelity and performance of accelerator modeling tools, in tandem with novel machine learning capabilities, has prompted community initiatives aiming to realize “virtual test stands” that can serve as true analogues to physical machines. Such efforts require integrated, end-to-end modeling capabilities with support for parametric optimization and benchmarking. We present the ongoing development of an integrated Sirepo application to support the holistic modeling of accelerators. Our approach leverages existing modeling workflows, such as the Light Source Unified Modeling Environment (LUME), as well as community I/O frameworks, such as openPMD, to provide a toolbox for constructing and modeling beamlines. Users can build and test simulations using different community modeling tools, as well as connect individual tools to produce end-to-end simulations. Additional workflows have been developed to support machine learning tools that facilitate optimization and the development of surrogate models. We discuss some specific beamline modeling demonstrations as well as ongoing efforts to support code-agnostic design and development.

Speaker: Nathan Cook (RadiaSoft (United States))

15:30 Intelligent motor driver monitoring and alarm system for Taiwan Photon Source

The number of motor drivers in the TPS beamline and experimental stations is quite large. Therefore, designing an intelligent monitoring and alert system to monitor the motor control system on the beamline is essential. When the system encounters any abnormal conditions, it can notify engineers to handle the situation. Additionally, it can record usage time to schedule relevant replacement work, thereby improving operational efficiency.

Speaker: Chia-Feng Chang (National Synchrotron Radiation Research Center)

15:30 Interaction point beam offset tolerances for luminosity performance at FCC-ee

To achieve physics performance at the Future Circular electron-positron Collider (FCC-ee), luminosity and beam lifetime must be maintained at close to design specifications. Alongside global feedbacks, a fast feedback system is proposed to mitigate beam offset errors at the interaction points (IP), caused by magnet vibrations or other time-varying errors. In this paper, the FCC-ee luminosity performance is simulated for beam-beam interactions including beam offsets, providing performance requirements for the fast feedback system.

Speaker: John Salvesen (European Organization for Nuclear Research)

15:30 Investigating beam-induced electron emission from thin wires in PSI proton beams

The emission of electrons induced by beam interaction with thin targets is a phenomenon used to measure various properties of particle beams. The main processes of electron emission are: secondary emission, delta electron production and thermionic emission. The last one is not desired, because the intensity of thermionic electrons is not directly related to beam density profile. A common technique to suppress thermionic emission employs bias potential on the wire, which allows for recapturing of low energy electrons. This study investigates the effectiveness of the bias voltage method for high-brightness proton beams of the HIPA accelerator. Through experiments and simulations, the study aims to better understand the emission spectra, the suppression of thermionic emission, and the effects of beam fields on electron dynamics.

Speaker: Dr Mariusz Sapinski (Paul Scherrer Institute)

15:30 LHC BLM-based beam loss pattern recognition algorithm for off-momentum losses

The Beam Loss Monitoring System (BLM) of the Large Hadron Collider (LHC) protects the accelerator against energy deposition from beam losses. One of the most critical moments regarding beam losses is the start of the beam acceleration. During this process, particles outside the bucket will not be captured in the first seconds of the start of ramp thus being lost at the machine aperture. This is expected to be the moment of minimum beam lifetime in the LHC cycle. During Run 3, losses from these off-momentum particles triggered some beam dumps. Several studies are on-going to assess a possible limitation from this loss scenario. This contribution quantifies the beam power lost at that moment and how the losses are distributed along the accelerator by the use of a dedicated BLM loss pattern recognition algorithm.

Speaker: Volodymyr Rodin (European Organization for Nuclear Research)

15:30 Longitudinal phase space measurement using a corrugated structure at the PAL-XFEL

We present the experimental results of the longitudinal phase space (LPS) measurement using a corrugated structure at Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL). The electron beam, passing the corrugated structure, generates the wakefield, which streaks the beam horizontally. The dipole magnet following the corrugated structure disperses the streaked beam vertically. By analyzing the transverse distribution observed at the screen monitor after those components, the electron beam LPS can be characterized. The LPS after the FEL process can also provide the FEL temporal profile, which is the valuable information for the accelerator optimization as well as the user experiments. In this paper, we present the preliminary experimental results for the characterization of the electron beam LPS and FEL profile.

Speaker: MyungHoon Cho (Pohang Accelerator Laboratory)

15:30 Machine learning for calibration drift forecasting in superconducting RF cavities

Superconducting radio frequency (SRF) cavities in particle accelerators rely on accurately calibrated RF signals to assess cavity bandwidth and detuning, ensuring optimal performance. In practice, however, calibration drift due to humidity and temperature fluctuations over time poses a significant challenge, potentially resulting in suboptimal operation and reduced efficiency. This study explores how environmental variables such as humidity and temperature affect this phenomenon. Relative humidity, in particular, is difficult to control and has been shown to impact calibration drift strongly. Building on these insights, we introduce machine learning-based approaches to forecast both relative humidity and calibration drift in SRF cavities. By leveraging advanced algorithms and historical data on cavity operation and performance, we develop predictive models that identify patterns and trends indicative of relative humidity and calibration drift. Two approaches are presented in this work, including a polynomial NARMAX model and an attention-based deep neural network. These models enable real-time compensation and automated recalibration, improving system stability and efficiency.

Speaker: Max Herrmann (Deutsches Elektronen-Synchrotron DESY)

15:30 Measurements for beam size blowup in sudden beam loss events and analysis of the beam loss evolution mechanism

The SuperKEKB electron-positron collider, which aims to achieve the world's highest luminosity, has suffered from "Sudden Beam Loss events (SBL)," in which several tens of percent of the beam current is lost and aborted within a few turns (20-30 µs). We have developed a new turn-by-turn beam size monitor to elucidate the cause and time evolution mechanism of the SBL events from a beam size variation point of view. The beam size monitor has two features: 1) it can measure the beam size variation over dozens of turns just before an SBL-induced beam aborts, and 2) it can measure independently in two different wavelength regions, X-ray and visible light, to ensure redundancy. In the SuperKEKB operation in 2024, we found that the vertical beam size blew up rapidly before a few turns of the abort, up to about ten times larger than the usual beam size. We also found that the size blowup started earlier than the beam position oscillation. In this presentation, we will discuss the mechanism of the beam size monitor we have developed, the analysis results of the measured beam size blowup, and finally, the possible cause and time evolution mechanism of the SBL events.

Speaker: Riku Nomaru (The University of Tokyo)

15:30 Measurements of dark current and breakdown phenomena using Faraday cups at the Xband Laboratory for Accelerators and Beams (XLAB)

Two CLIC TD24 accelerating structures, manufactured by CERN, are being tested on the high gradient 12 GHz RF test stand at XLAB. Installed at the end of 2024, these are the first devices to be tested at XLAB. Testing aims to verify that following conditioning they can be reliably operated at accelerating gradients of 100 MV/m. The conditioning process involves slowly increasing the peak RF power and pulse length input to the structure.
The peak accelerating gradient at which a structure can operate reliably is limited by electrical breakdown. As conditioning progresses the likelihood a that a breakdown will occur decreases. When a breakdown occurs significant charge is emitted by the structure. Considerable progress has been made in the development of the theory of breakdown formation and the underlying interaction mechanisms. Accurate measurements of breakdown phenomena are required to test these understandings. Faraday cups installed upstream and downstream of the structures and connected to high resolution digitisers are employed to measure the behaviour of the breakdown current emissions and dark current. The results of these measurements are presented here.

Speaker: Paul Giansiracusa (The University of Melbourne)

15:30 Measuring single-pass dispersion in the LHC

During the LHC Ion Run in 2023, the ALICE detector observed a high level of background that prevented efficient data taking. This background was caused by different ion species generated in the betatronic collimation region that were intercepted by the Tertiary collimator near ALICE Interaction Point. The mass-to-charge ratio of these generated ions causes them to follow a different trajectory to the main ion beam, similar to off momentum particles. Since this is a single-pass effect, the closed dispersion does not describe the trajectory of these ions. Instead, the single-pass or one-pass dispersion is the relevant quantity to measure. In this paper two methods for reconstructing the single-pass dispersion based on the closed orbit and optics data are described. The methods are validated through simulations and applied to real data from the LHC 2023 Ion Run.

Speaker: Ewen Maclean (European Organization for Nuclear Research)

15:30 Minimizing disturbance in ion beam profiling with PEPITES monitor

In the field of beam diagnostics for radiotherapy, accurate dose delivery relies on ultra-thin, linear and radioresistant monitors to minimize beam scattering and achieve precise profiling. The first PEPITES prototype monitor features two segmented cathodes, each paired with a high-voltage-biased anode. This latter effectively captures secondary electrons generated by the cathodes when they interact with the beam, enabling the detection of a measurable signal. The Water Equivalent Thickness (WET) of this design is approximately 10 μm*. To achieve efficient profiling of the charged particle beam when the monitor is positioned several meters upstream of the patient, we developed a thinner design. This configuration features two anodes positioned outside the beam path, reducing by half the amount of material that interacts with the beam, thereby minimizing beam disturbances. Both, the previous and the updated PEPITES monitor designs were recently tested at CNAO,Italy. Measurements were successfully conducted using a 115 MeV carbon ion beam at varying high-voltage power. These results will be presented and compared to demonstrate the enhanced efficiency of the upgraded PEPITES version.

Speaker: Alexandre Esper (Laboratoire Leprince-Ringuet)

15:30 MNDACS – Mesh networked data acquisition and control system

At our institute, we needed a scalable SCADA system for both FRANZ and smaller laboratory test setups. Given the heterogeneity of devices, the system had to be easily extendable to support custom-built hardware, self-made devices, and standard PLC systems. Additional requirements included low maintenance, minimal system demands, and compatibility with various IT environments, operating systems, and hardware architectures.
To meet these needs, we developed a ZeroMQ pub/sub pattern-based system in Java, which can function as a standalone instance or as a distributed mesh network across multiple systems. A modular device driver design simplifies the integration of devices with existing control software components. A universal XML-based driver enables device communication descriptions without the need for programming or recompilation.
To minimize system resource demands, a Swing-based GUI was incorporated. This GUI is configurable via XML files, providing user flexibility and reducing the programming effort required for standard or predefined elements.

Speaker: Christopher Wagner (Goethe University Frankfurt)

15:30 Modernization of the automated radiation monitoring system for the U400M cyclotron and the main building at FLNR

Currently, the Flerov Laboratory of Nuclear Reactions (FLNR) is modernizing its accelerator complex, focusing on the development of new facilities and the enhancement of existing ones. Notably, the U400M cyclotron has been successfully modernized. As part of the upgrade of the U400M's main systems, a project for the deep modernization of its Automated Radiation Monitoring System (ARMS) was initiated.
In addition to monitoring the radiation environment of the U400M, the ARMS oversees other radiation-related facilities in the main building at FLNR. These include the MT-25 microtron, radiochemical laboratories of the 2nd and 3rd safety classes, and the radioactive isotope storage facility.
This report presents the main types of radiation monitoring implemented by the system, the equipment used, its software features, and the interaction algorithms with the control systems of the U400M and MT-25 accelerators, as well as the U400M Interlock and Signalization System (ISS). Additionally, the current status of the project, challenges in its commissioning, and the prospects for further development of the system at FLNR are discussed.

Speaker: Pavel Komarov (Joint Institute for Nuclear Research)

15:30 Motion protection framework for TPS insertion device control

The Taiwan Photon Source (TPS) is an advanced synchrotron radiation light source that provides high-brightness light for scientific research and industrial applications. The insertion device (ID) plays a critical role in controlling the electron beam trajectory to enhance synchrotron radiation intensity. However, due to radiation and signal interference in the operational environment, the motion control system of the ID faces challenges, especially when optical encoder anomalies occur, which can affect performance and may, under certain circumstances, lead to hardware damage. Traditional motion protection relies on software soft limits and hardware limit switches, but these mechanisms may not provide comprehensive and effective protection in the event of optical encoder failures. To address this, this paper proposes a multi-layered motion protection system. In addition to incorporating traditional protections, it also introduces an abnormality prediction mechanism based on the difference in optical encoder and potentiometer data. This mechanism can trigger an abort signal to the motor controller when an anomaly is detected to stop the abnormal motion. This architecture significantly improves the operational reliability of the TPS ID, ensuring long-term safe and stable performance.

Speaker: Chih-Yu Liao (National Synchrotron Radiation Research Center)

15:30 Multichannel system for measuring the phase of acceleration and other parameters of beams in a cyclotron

Diagnostics of charged particle beams is an important area in the field of accelerator technology. Non-destructive methods of beam diagnostics are becoming increasingly popular, as they allow measurements to be taken without changing the beam parameters. This is particularly valuable when studying continuous processes, the results of which can be distorted when using traditional diagnostic methods.
Pickup electrodes are devices used for non-destructive diagnostics of charged particle beams. They are thin metal plates located along the axis of the beam motion. When a particle beam passes near a pickup electrode, it creates an electrical signal that is proportional to the beam current. This signal can be processed and analyzed using special equipment and software.
A multichannel modular system with expandability has been developed to measure particle acceleration parameters, specifically the phase distribution during movement in the accelerator chamber, coordinates relative to the median plane and other parameters. The paper presents the results of testing the system at the DC-280 cyclotron at FLNR JINR and SSC at IThemba LABS.

Speaker: Lev Pavlov (Joint Institute for Nuclear Research)

15:30 New all-digital camera setup at the Karlsruhe Research Accelerator

Until recently, the Karlsruhe Research Accelerator (KARA) located at the Karlsruhe Institute of Technology (KIT) was using analog cameras to monitor fluorescence screens. By now all cameras have been replaced by digital cameras directly connected via ethernet, making it possible to directly integrate them into our EPICS-based control system. The new control system integration also provides for a better continuous statistical analysis and comparison of camera pictures. This paper presents an overview of the new setup, including the post-processing integration making use of Python.

Speaker: Patrick Schreiber (Karlsruhe Institute of Technology)

15:30 Next generation LLRF control and monitoring system for S-band linear accelerators

The low-level RF (LLRF) systems for S-band linear accelerating structures are typically implemented with heterodyne base architectures. We have developed and characterized the next generation LLRF (NG-LLRF) based on the RF system-on-chip (RFSoC) for C-band accelerating structures and the platform delivered the pulse-to-pulse fluctuation levels considerably better than the requirement of the targeted applications. The NG-LLRF system uses the direct RF sampling technique of the RFSoC, which significantly simplified the architecture compared with the conventional LLRF. We have extended the frequency range of the NG-LLRF to S-band and experimented with different RFSoC devices and system designs to meet the more stringent requirement for S-band LLRF applications. In this paper, the characterization results of the platform with different system architectures will be summarized and the high-power test results of the NG-LLRF with the S-band accelerating structure in the Next Linear Collider Test Accelerator (NLCTA) test facility at SLAC National Accelerator Laboratory will be presented and analyzed.

Speaker: Ankur Dhar (SLAC National Accelerator Laboratory)

15:30 Non-destructive measurements of non-relativistic ion beam bunch shapes at RAON

Characterizing the longitudinal bunch profile is crucial for understanding beam dynamics and ensuring optimal accelerator performance. To address these needs, Capacitive Pick-Up type Bunch Shape Monitors (CPU-BSMs) were developed at the Institute for Rare Isotope Science (IRIS). These devices non-destructively measure the longitudinal bunch shapes of non-relativistic, nanosecond-scale ion beam bunches.

Initial feasibility tests were conducted at a 30 MeV cyclotron to verify the performance of the CPU-BSMs. Subsequently, in 2024, the CPU-BSMs were employed during Nuclear Data Production System (NPDS) beam commissioning at the Rare Isotope Accelerator complex for ON-line experiments (RAON) to characterize both the longitudinal bunch shapes and the beam energy values.

In this presentation, we will report the experimental results obtained using the CPU-BSMs during the NPDS beam commissioning at RAON.

Speaker: Donghyun Kwak (Ulsan National Institute of Science and Technology)

15:30 On-line estimation approach to fault-tolerant control of orbit stability at Siam Photon Source

A novel approach combining online unknown input estimation with reconfigurable control has been developed to enhance orbit stability in the Siam Photon Source (SPS) storage ring. These unknown inputs, representing disturbances or uncertainties in the dynamic system, provide valuable insights for achieving robust control. Disturbances such as noise, temperature changes, and modeling uncertainties affecting the control variables can be treated as fault signals, allowing the application of fault estimation and compensation techniques from Fault Diagnosis (FD) and Fault-Tolerant Control (FTC) theories. The initial implementation of this slow orbit feedback (SOFB) system has significantly reduced X-Y orbit fluctuations while maintaining robust control stability against temperature disturbances in the SPS storage ring. This presentation will cover the FD/FTC principles, hardware, software, commissioning results of the current SOFB system, and plans for future developments.

Speakers: Somjai Chunjarean (Synchrotron Light Research Institute), Thakonwat Chanwattana (Synchrotron Light Research Institute)

15:30 Operational challenges of the SuperKEKB iBump feedback system

To maintain optimal beam collision conditions and luminosity performance, SuperKEKB requires a fast orbit feedback dedicated to correcting offsets at the interaction point (IP). The 'iBump' feedback system calculates IP beam offset from Beam Position Monitor (BPM) measurements before and after collision and corrects by creating closed orbit bumps in the High Energy Ring (HER). This system has demonstrated robustness at stabilising IP offsets during operation. In this paper, we discuss operational aspects of the system and ongoing challenges, with a focus on the identification of vertical offset as the correction target of the iBump system. Dedicated studies on the current dependence of this feedback target as well as historical data are analysed.

Speaker: John Salvesen (European Organization for Nuclear Research)

15:30 Optical electron beam diagnostics at the Novosibirsk FEL

We present an overview of recent and upcoming enhancements to the optical electron beam diagnostics stations at the Novosibirsk Free Electron Laser (FEL) facility. These diagnostic stations are designed to measure key beam parameters, including beam energy spread, length and emittance, at the third FEL of Novosibirsk FEL. Currently, the stations for measuring electron beam energy spread and undulator radiation spectrum are in the commissioning phase, with initial results already obtained. The new optical diagnostics are essential for the precise tuning of the magnet system used in electron outcoupling experiments. This paper provides a comprehensive overview of the new diagnostic systems, discusses the preliminary measurement results of beam parameters, and outlines the experiments planned for the near future.

Speaker: Vladislav Borin (Russian Academy of Sciences)

15:30 Optimization of Piezo Operation for superconducting TESLA cavities at EuXFEL

Superconducting cavities with high Q-factor require precise tuning to match the RF frequency, ensuring stable electromagnetic fields and minimizing RF power consumption. At the XFEL accelerator, TESLA cavities are tuned using slow tuners (step motors) for coarse adjustments and fast tuners (piezoelectric actuators) for fine-tuning and compensating disturbances such as Lorentz Force Detuning (LFD) and microphonics.
Critical to this system, Piezo actuators require high-voltage (up to 100V) and high-current (up to 1A) driving signals for effective LFD compensation. However, they are vulnerable to overvoltage, overcurrent, and overheating*, and their protection is crucial since replacing damaged piezo in fully assembled modules is unfeasible. Additionally, piezo induced vibrations can affect the machine's stability.
Optimizing piezo excitation—by reducing voltage, current, and current slope while ensuring effective LFD compensation—improves both reliability and machine stability. This paper explores the optimization of piezo excitation at XFEL, detailing methods and results applicable to other facilities with superconducting cavities.

Speaker: Max Herrmann (Deutsches Elektronen-Synchrotron DESY)

15:30 Oxygen deficiency detection in the LHC

With the increased performance of the High Luminosity Large Hadron Collider (HL-LHC), gas leak detection in the vicinity of the superconducting magnets cooled with cryogenic helium becomes a challenge.
To ensure operational safety and reliable detection of Oxygen Deficiency Hazard (ODH) for the next decade, the entire system will be refurbished during the LHC accelerator's long shutdown, scheduled to begin in 2026. The new design of the ODH detection system includes development of a detector and flashing lights that can not only cope with electromagnetic disturbances, but also with an increased radiation exposure, all while considering the restricted access for equipment maintenance. Understanding the nature and impact of these constraints at the design stage is key to specifying the requirements of the new safety systems.
This paper describes the research and development work undertaken by CERN to analyse, test, and define oxygen deficiency detection taking into account lessons learned from the current systems and the future upgrade to the High Luminosity LHC.

Speaker: Mr Michael Dole (European Organization for Nuclear Research)

15:30 PAnTHer: An interactive map for the web and touchscreens

PAnTHer (Particle Accelerator on THreejs) is a 3D and 2D map for particle accelerators developed using web and touch technologies. The maps are connected to real-time data from accelerator controls, simulators, and an external component database.
The map is generated from a lattice file in JSON format and a bundle of JavaScript components for the 3D version, and an SVG bundle for the 2D version.
The JSON lattice file can be generated on the fly taking all necessary parameters from a simulator device server and presented instantly to the remote user among with the visualization of some simulated quantities such as position, beta, eta, mu and sigma
Available components are: magnets (bending, quadrupoles, sextupoles, correctors, etc.), pumps, valves, PLCs, racks, mirrors, walls etc. Multiple components can be embedded within a single element.
The 3D version offers various configurations, ranging from a fast mode, which runs smoothly even on devices with limited computational power, to a standard mode with enhanced graphical details, and a high resolution mode that uses components derived from mechanical department. The latter requires fairly powerful hardware to maintain optimal fluidity.

Speaker: Stefano Krecic (Elettra-Sincrotrone Trieste S.C.p.A.)

15:30 Passive Radiation Detection Using TLD in NSRRC

The NSRRC is a research facility and currently op-erates two synchrotron accelerators: the Taiwan Light Source (TLS), featuring a beam energy of 1.5 GeV and a circumference of 120 meters, and the Taiwan Photon Source (TPS), with a beam energy of 3 GeV and a cir-cumference of 518.4 meters. There are hundreds of users in 40 beamlines among TPS and TLS experi-mental floors.
The Thermo-Luminescent Dosimeter (TLD) is a compact instrument utilizing well-established detec-tion technology. To ensure radiation intensity at NSRRC workplace as close to background radiation levels as possible, we have deployed approximately 200 TLDs among these two accelerators. For each BL, three points are selected: the optical hutch near accel-erator shielding wall, the user experimental area with the highest occupancy, and the BL rear end. Additional TLDs are strategically placed around the accelerator's surroundings, including both the outer and inner sur-face of the shielding tunnel, downstream of the injec-tion section, the roof and downstream area of the RF cavities.
In this paper, we will present the detection data col-lected at NSRRC over the past several years to reflect the proficiency of our radiation protection program.

Speaker: Sy-Yu Lin (National Synchrotron Radiation Research Center)

15:30 Performances of new frequency sources for TRIUMF ISAC accelerator chains

The TRIUMF ISAC-1 and ISAC-2 accelerator chains uses multiple fixed frequencies in their RF cavities. These include 5.8933 MHz, 11.7866 MHz, 35.36 MHz, 106.08 MHz and 141.44 MHz. These need to be synchronized in phase with respect to each other’s. The new frequency sources use x2, x3 and x4 low phase noise multipliers to generate these frequencies from a single low phase noise 5.8933 MHz frequency synthesizer. Bench tests have shown that the frequency multipliers do not generate additional phase noises, except those that are theoretically produced due to frequency multiplication. With an average performance frequency source as a reference which has -85dBc/Hz at 10 Hz offset, the integrated rms phase noise of 141.44 MHz multiplied output is less than 0.5°.

Speaker: Ken Fong (TRIUMF)

15:30 Photon stimulated desorption from cryogenic surfaces of high temperature superconductor and amorphous carbon thin films

High Temperature Superconductor (HTS) and amorphous Carbon (a-C) thin films, and their combination, are being considered as possible surface coatings for the FCC-hh beam screen (BS) with the aims of reduction of the resistive wall impedance and mitigation of the electron cloud. Along with these required properties, i.e., the high electron conductivity and low secondary electron yield, the Photon Stimulated Desorption (PSD) yield is one of the most essential characteristics in the design and operation of the FCC-hh vacuum systems. For this purpose, a series of the PSD measurements is currently conducted at a dedicated beamline in the KEK Photon Factory, where similar conditions to FCC-hh in terms of the Synchrotron Radiation energies and power density are available. In order to realize a similar cryogenic condition of the BS (40-60 K), the sample container is equipped with a LN2 jacket (77 K) and installed in an insulation vacuum chamber. The conditioning behaviors of the PSD yields as a function of the photon dose are being obtained for uncoated copper and HTS, and a-C coated copper and HTS, and each sample is examined at cryogenic and room temperatures for comparative analysis.

Speaker: Yasunori Tanimoto (High Energy Accelerator Research Organization)

15:30 Pre-alignment strategy for magnet units in the Hefei Advanced Light Source storage ring

The storage ring of the Hefei Advanced Light Source includes 120 magnet units, each of which is composed of 4-8 magnets with adjustment mechanisms placed on a rigid support. In order to improve the overall efficiency and accuracy of the alignment installation, we will complete the overall pre-alignment of the magnet unit in an independent laboratory with a good environment based on the vibrating line magnetic measurement technology and FLTMMS technology, and then transport the magnet unit as an independent element to the site for alignment installation. This paper elaborates on the specific implementation process of this strategy and the technical solutions adopted to improve the accuracy, such as instrument layout optimization, damping and vibration reduction. Through accuracy estimation and actual measurement verification, the implementation of this strategy can effectively ensure that the Hefei Advanced Light Source project can efficiently achieve the pre-alignment accuracy index requirements.

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

15:30 Radiation monitoring and R2E performance in the LHC during the 2024 proton run

The integrated luminosities in each of the ATLAS and CMS experiments at the Large Hadron Collider (LHC) have reached above 120 fb-1 during the proton run of 2024, the highest annual values since the beginning of the LHC operation. The same is true for LHCb, with over 10 fb-1 of integrated luminosity reached during proton operation in 2024. Such high levels of integrated luminosity are associated with high levels of radiation around the experiment locations, including hundreds of meters of tunnel on both sides of the interaction point, where beam losses driven by the luminosity production still occur. The ability of the LHC systems to operate in the radiation environment of the machine is analyzed in this contribution. Each year, radiation effects on electronic components installed around the LHC lead to premature beam dumps, causing accelerator down-time and loss of physics production. The number of radiation-induced beam dumps of the proton run 2024 per integrated luminosity has been comparable to previous years in LHC Run 3, and improved compared to LHC Run 2. However, due to the large integrated luminosity of LHCb, a large part of the events have been observed there, and some mitigation strategies to minimize such events are discussed.

Speaker: Daniel Söderström (European Organization for Nuclear Research)

15:30 Raspberry Pi cameras for beam diagnostics at the Frankfurt Neutron Source

The application of Raspberry Pi cameras as cost-effective, versatile beam diagnostic tools is currently being explored at the Frankfurt Neutron Source (FRANZ). These compact imaging systems have been deployed to investigate proton beams at energies of 60 keV and 700 keV, including configurations where cameras are installed both externally and directly inside the accelerator’s RF resonator. Such setups provide opportunities to visualize beam profiles and related phenomena, potentially offering new insights into beam dynamics and cavity conditioning. This contribution will present the latest developments in camera integration, image acquisition, and preliminary image analysis techniques. By showcasing ongoing work and recent findings, we aim to highlight the potential of this approach for enhancing beam diagnostics in future accelerator environments.

Speaker: Dr Hendrik Hähnel (Goethe University Frankfurt)

15:30 Real-time luminosity optimization in collider experiments using reinforcement learning

This study presents the development and implementation of a reinforcement learning-based algorithm for real-time luminosity tuning in collider experiments. The algorithm is initially pretrained on historical collider data and subsequently fine-tuned online during experiments. By analyzing accelerator measurements collected over several seconds, the model adjusts the magnetic structure to stabilize luminosity under varying experimental conditions. The proposed method allows for adaptive optimization without operator involvement, improving operational efficiency and stability. Results from its application on the VEPP-4M collider are presented, showcasing the method's feasibility and offering insights for its future development and application in accelerator systems.

Speaker: Rasim Mamutov (Russian Academy of Sciences)

15:30 Reliability analysis of the new Beam Interlock System for CERN’s accelerator complex

The Beam Interlock System is a key element of machine protection in CERN’s accelerators. It provides a fast and reliable way to link the accelerator systems to the beam dumping system, which ensures the safe extraction of the beams. This paper presents the reliability study of the new Beam Interlock System, which will replace the current system and will be deployed during CERN’s Long Shutdown 3. The upgrade features many improvements while maintaining the proven architecture of the previous system. In the study, each of the system’s boards were analysed through a detailed, component-level FMECA. This approach quantifies all operational risks, as well as identifies the most critical components. The risk on the system level is estimated using a global reliability model, which establishes functional dependencies between individual boards. It accounts for system-level redundancies, inspection and maintenance strategies. The results show that the stringent reliability requirements, set in the view of possible catastrophic damages to the equipment in case of malfunction, are met with safety margins. They also highlight the importance of appropriate maintenance, testing and monitoring.

Speaker: Dr Daniel Wollmann (European Organization for Nuclear Research)

15:30 Reliability analysis of the new Universal Quench Detection System and Protection Devices Supervision Unit for the HL-LHC inner triplet magnets

The new Universal Quench Detection System (UQDS) and Protection Devices Supervision Unit (PDSU) are pivotal elements for the quench protection system of the new HL-LHC inner triplet superconducting magnets as well as for requesting a beam dump upon activation of the active quench protection systems, the novel Coupling Loss Induced Quench System (CLIQ) and the traditional quench heaters (HDSs). Given the criticality of these functionalities, a thorough reliability analysis has been carried out to ensure that the probability of critical failures meets the stringent reliability requirements under all operational conditions. To determine the failure probabilities, analytical models were developed that consider redundancies, inspection strategies and demand frequencies. The models’ failure parameters were identified by a component-based Failure Mode, Effects and Criticality Analysis (FMECA). The results of the models allow the qualification of the system design as well as insights on critical monitoring and testing requirements of the system when in operation.

Speaker: Dr Daniel Wollmann (European Organization for Nuclear Research)

15:30 Renovation of the technical gallery network at CERN

The distribution of services throughout a large scientific facility like CERN relies on a 14-km-long network of technical galleries. They provide essential utilities to CERN's office buildings and technical facilities, such as hot water, drinking water, compressed air, gas and electrical supply. This network has been gradually expanded or partially discontinued based on the Laboratory's needs. After 60 years of service, it is now time to refurbish the galleries and their associated infrastructure, to address existing issues and establish a robust foundation for the organization's future endeavors. A dedicated project has therefore been launched to enhance the maintainability, reliability, overall safety, and environmental performance of the technical infrastructure. Adapting all the networks to current and future needs following modern standards while minimizing service disruptions is also a priority. This paper provides insight into the methodology developed to re-engineer the targeted areas, the results of design studies, and lessons learned from implemented improvements. These insights may serve as a valuable example for other consolidation projects within CERN and beyond.

Speaker: Michael Dole (European Organization for Nuclear Research)

15:30 RF phase feedback at KEK e-/e+ Injector LINAC

The KEK e-/e+ LINAC delivers the beams to four storage rings with the top-up injections by switching the beam mode in 50 Hz repetition rate. The beam charge, energy, and number of bunches (one or two) are different for each ring. Therefore, the RF timing and phase are adjusted to each beam mode independently. To stabilize the RF phase drifts caused by the klystron high voltage, the cooling water and accelerating structure temperature, the RF phase feedback was introduced. The correction phase quantity is obtained by feedback calculation using non-injection mode without beam acceleration, and the value is added to set phase value in each mode. As a result, the RF phase in each beam mode has been stabilized.

Speaker: Takuya Natsui (High Energy Accelerator Research Organization)

15:30 Service-oriented EPICS and data processing method based on high-availability cluster

A novel service-based EPICS and new front-end data acquisition method based on a high-availability Kubernetes cluster built on the Proxmox VE platform are proposed in this paper to enhance the performance and stability of the data acquisition system. By deploying EPICS services on the Kubernetes cluster, a new efficient front-end data processing and acquisition method is realized. The data acquisition method utilizes distributed data sharing based on the Channel Access protocol to perform real-time processing and analysis of data. This approach offers advantages such as reducing hardware and maintenance costs, improving portability and flexibility, and enhancing data acquisition and processing efficiency. The practical application and testing have demonstrated that this method has the potential for use in large scientific facilities. In the future, its application value in other fields will be explored.

Speaker: Dr Yukun Li (Institute of High Energy Physics)

15:30 State-of-the-art cryogenics process control for the operation of the ESS superconducting linac

This paper presents the strategy for the simultaneous cryogenic operation of the ESS superconducting linac, consisting of 43 cryomodules. It details the process logic required for different operational phases and introduces a novel control system designed to manage these complexities. Key features of the system are discussed, including multiple independent automatic control sequences, a master controller for system synchronization, failure response protocols, and operator interface design. Fully deployed in December 2024, the system played a critical role in the successful cooldown of the accelerator. The paper also addresses lessons learned during this deployment and outlines potential improvements for future operations.

Speaker: Nuno Elias (European Spallation Source)

15:30 Status and event automatic notification development with mobile system at NSRRC

The National Synchrotron Radiation Research Center (NSRRC) is dedicated to enhancing the operational efficiency of its facilities and improving user experience by developing a status and event automatic notification system. This system aims to monitor equipment status in real-time and automatically notify relevant personnel in case of anomalies or significant events. It continuously monitors and inspects the operational status of synchrotron radiation facilities, ensuring all equipment operates at optimal conditions. Notifications of abnormal statuses and events will be automatically sent to relevant technical and management personnel. The benefits include increased operational efficiency, enhanced safety, and optimized resource management. These development efforts will be presented in this report.

Speaker: Chang-Hor Kuo (National Synchrotron Radiation Research Center)

15:30 Status of the control system for the injector of RAON

RAON (Rare Isotope Accelerator complex for On-line experiments), a heavy-ion linear accelerator designed to advance basic and nuclear science with rare-isotope beams, successfully completed beam commissioning and, for the first time, provided beam user service for its low-energy section using an argon beam in 2024. The successful operation of such a complex and massive accelerator system requires an integrated control system capable of real-time monitoring and control of all devices and subsystems. The RAON control system is built on the EPICS (Experimental Physics and Industrial Control System) software framework, facilitating communication with individual devices connected through PLCs or serial servers. Furthermore, each local system is equipped with interlock logic implemented using the EPICS sequencer, designed to ensure an immediate response to emergency situations. During beam delivery, operators monitor and control the entire system through OPIs (operator interfaces) built with CS-Studio in the main control room, providing comprehensive oversight and access to real-time data. This abstract presents the current status of the control system for the injector section of RAON.

Speaker: Yujung Ahn (Institute for Basic Science)

15:30 Study on a novel laser fast abort system for SuperKEKB

To ensure stable and continuous commissioning of SuperKEKB, the machine protection system (MPS) plays a crucial role in safeguarding the accelerator's hardware from damage caused by beam loss. The response time of the MPS is a critical factor in mitigating hardware damage caused by the radiation of abnormal beams. In this study, we investigate a novel laser fast abort system for the SuperKEKB accelerator to reduce the response time of the beam abort trigger. The laser, serving as the trigger signal, is transmitted through free space. Compared to the traditional method, the transmission speed is 1.5 times faster than that in optical fiber. This faster signal transmission can shorten the abort time, enabling the realization of effective MPS. The optical design for long-distance laser beam propagation and measurement of coupled laser power have been studied. Investigation will be conducted regarding the long-term stability of the laser beam inside the accelerator tunnel.

Speaker: Rui Zhang (High Energy Accelerator Research Organization)

15:30 Study on the vacuum properties of titanium alloy-lined thin-walled arc vacuum chamber

A large scientific facility, High Intensity heavy-ion Accelerator Facility (HIAF), was being built to study basic and interdisciplinary sciences. The Booster ring (BRing), as the core device of the HIAF, has a magnetic rigidity of up to 34 Tm，and the field ramping rate of the pulsed dipole magnet is up to 12 T/s. To reduce the eddy current effect and beam loss caused by the rapid ramping of the magnetic field. A 0.3 mm stainless steel thin-walled titanium alloy lined arc vacuum chamber was proposed, in which titanium alloy liners are sequentially arranged inside to improve mechanical properties. The arc vacuum chamber with a cross-section of 230 mm x 97 mm and a length of 3.4 m，to reduce the pressure gradient inside the thin-walled arc vacuum chamber，Ti-Zr-V thin films were deposited on the titanium alloy liner and 0.3 mm stainless steel thin wall, respectively, by magnetron sputtering coating technology. After activation of Ti-Zr-V thin films，the ultimate pressure can be as low as 5.0E-10 Pa, and the pressure at the middle of the thin-walled arc vacuum chamber could decreased from 1.5E-9 Pa to 6.6E-10 Pa. Furthermore, 0.3mm thin-walled titanium alloy lined arc vacuum chamber and Ti-Zr-V thin films have been successfully applied to HIAF-BRing.

Speaker: Ningfei Wei (Institute of Modern Physics, Chinese Academy of Sciences)

15:30 Substrate material studies for PCB-based electro-optical bunch arrival-time monitors for XFELs

The all-optical synchronization system used in many X-ray free-electron laser facilities (XFELs) relies on electro-optical bunch arrival-time monitors (EO-BAM) for measuring the single bunch arrival time with regards to an optical reference. An upgrade of the established EO-BAM is intended to achieve a sensitivity that enables stable operation with bunches down to charges of 1 pC, or to significantly increase the resolution in normal operation. Therefore, the pickup structure, the RF path and the electro-optical modulators are undergoing a fundamental redesign. The novel concept of the pickup structure comprises planar pickups on a printed circuit board (PCB) with integrated combination network and a bandwidth of up to 100 GHz. The theoretical jitter charge product of the preliminary concept has been estimated to be in the order of 9 fs pC and the concept was proven experimentally with a 67-GHz demonstrator at ELBE. In this contribution, we compare ceramic and glass substrates in terms of radiation hardness, sensitivity, and manufacturing capabilities. The achievable bandwidth and sensitivity are influenced by material losses and varying tolerances due to different fabrication methods.

Speaker: Mr Bernhard Scheible (Technische Hochschule Mittelhessen)

15:30 Surface resistance measurement of Pd coating films using cavity resonator method

Recently, it was found that Pd coating films exhibited ultra-low photon-stimulated desorption and low resistivity values. These advantages suggest that Pd coatings could be applied to small aperture tubes, including undulator vacuum tubes, which have a significant effect on resistive wall impedance.

In previous studies, the DC electrical resistivity of Pd films was measured using the four-probe technique. The surface resistance under high-frequency conditions relevant to accelerators remained insufficiently explored.

This study aims to address this gap by employing the “cavity resonator method” to measure the surface resistance of this film under high-frequency electromagnetic fields. By depositing Pd films onto the inner surface of a copper alloy resonator, the quality factor (Q-factor) was measured and compared to that of the uncoated copper alloy, allowing for the calculation of the practical surface resistance. These results could provide a basis for evaluating the heat generation and cooling requirements of this film in accelerator applications.

Speaker: Mu-Lee Yao (High Energy Accelerator Research Organization)

15:30 The contribution of multiple reflections to transition radiation

A uniformly moving electron passing through a slab induces electromagnetic
emission known as transition radiation. The generated rays propagate inside
the slab and undergo multiple reflections off the slab boundary. We employ the polarization current method in order to derive the reflectionless
solution for an observed radiation intensity and compare it with that of Pafomov
which accounts for multiple reflections exactly. We identify the parameters of the set up that reduce the Pafomov solution to a reflectionless scenario. Provided the ultrarelativistic electron, the proper choice of the slab thickness allows the consideration of the reflectionless solution even in the optical range. Furthermore, it is shown that in the x-ray regime the reflections only become substantial when the radiation is incident on the slab boundary at a high angle at which the intensity of the radiation is vastly reduced. Therefore for a slab shaped screen the reflections may be ignored. Nevertheless the identification of the scenarios where reflectionless solution deviates from the Pafomov, could be used to qualitatively describe transition radiation from targets of complex shape.

Speaker: Dmitrii Grosman (ITMO University)

15:30 The LLRF related superconducting elliptical cavities characterization for ESS project

The installation phase of the European Spallation Source (ESS) linear accelerator is nearly complete. As with other superconducting linacs operating in pulse mode, LLRF systems play a crucial role in controlling accelerating beam parameters.
Modern LLRF systems go beyond providing fast and reliable feedback for RF signal regulation; they also ensure precise, dynamic cavity tuning. Additionally, they enhance machine availability by monitoring various signals to identify potential issues and implementing fast and slow algorithms to optimize cavity performance within safety limits, tailored to specific accelerator conditions.
Preparation for these tasks begins during cryomodule and cavity testing, prior to tunnel installation. Key parameters such as Lorentz force detuning coefficients, piezotuner range and polarity, main mechanical cavity modes, Pi-mode frequencies, slow tuner sensitivity, and backlash must be accurately determined to enable peak LLRF performance.
This paper outlines the development, implementation, and application of software tools designed to determine these parameters for cavities tested at ESS Test Stand 2 (TS2) and those installed in the accelerator tunnel.

Speaker: Wojciech Cichalewski (Lodz University of Technology)

15:30 The observer-based estimation of photon beam position for improved beamline stability at SPS

This paper presents the development and implementation of an observer-based estimation method to determine the photon beam position for various beamlines at the Siam Photon Source (SPS). The research, executed over multiple phases, aims to address position drift issues in photon beamlines, particularly those without installed photon Beam Position Monitoring Systems (pBPMs). The method allows real-time estimation of beam positions, which are then used as inputs for the SPS’s central control system to enhance beam stability. This observer-based approach provides a cost-effective solution by eliminating the need for additional pBPMs installation in space-constrained beamlines while maintaining an error margin of less than 10% between estimated and measured positions. This innovation is essential for enhancing the operational stability of existing beamlines and offers a scalable model for similar applications in the future.

Speakers: Somjai Chunjarean (Synchrotron Light Research Institute), Thakonwat Chanwattana (Synchrotron Light Research Institute)

15:30 The PIP-II dedicated RFPI system final design

The Radio Frequency Protection Interlock (RFPI) system main responsibility is to collect predefined set of signals and to protect each RF station. In case of safety limits violations from any of this input signals the RFPI has to instantenously drop permits for the LLRF or RF amplifier (eq. Solid State Amplifier - SSA or klystron) operation.
This paper presents an overview of the final design of the RFPI system dedicated for Proton Improvement Plan II (PIP-II) at Fermilab.

Speaker: Wojciech Cichalewski (Lodz University of Technology)

15:30 Towards autonomous accelerator control at ALS: a multi-agent LLM approach

This paper demonstrates progress towards a novel approach to particle accelerator control at ALS using a decentralized multi-agent framework powered by Large Language Models (LLMs). Our distributed control system deploys specialized autonomous agents to manage critical accelerator subsystems while maintaining coordinated operation through LLM-driven communication protocols.

The system demonstrates fundamental capabilities essential for next-generation accelerator operations, given the flexible nature of agent specialization, this framework provides a robust platform for integrating and coordinating diverse control algorithms and approaches already established in accelerator operations. Our prototype shows the system's ability to autonomously diagnose and resolve basic operational issues using existing control infrastructure.

This work represents an advancement toward practical autonomous accelerator operation, establishing a scalable foundation for managing increasingly sophisticated accelerator configurations. The demonstrated success of this distributed control architecture opens new possibilities for improving operational efficiency across various accelerator facilities.

15:30 Uncertainty in Harshaw 6600 dosimeters: a study of routine dosimeter services at Nepal Academy of Science and Technology

This research investigates the uncertainty in radiation dose measurements utilizing TLD-100 Dosemeters (LiF:Mg, Ti), and a TLD Reader System of Harshaw 6600 Plus present at Nepal Academy of Science and Technology. The calibration of the Dosemeter reader facilitated precise dose determination, resulting in mean calibration and correction factors of 1.052 and 0.003, respectively. Particularly at low effective dose levels, the study underscores the inevitability of heightened uncertainties across all radiation characteristics. An evaluation of uncertainty uncovered various contributing sources, including detector sensitivity inhomogeneity, reading variability, and energy/angular dependence, with a mean uncertainty estimated at 0.25% and overall uncertainty 19.16% for K=1. Additionally, luminescence and angular dependence studies under different irradiation conditions, with angular response factors ranging from 0.90 to 1.10. Also, Klein-Nishina differential cross-section was study at different energy (60 keV, 80 keV, 100 keV and 150 keV) with scattering angle considering LiF:Mg, Ti as target and found decrease with scattering angle.

Speaker: Ram Karki (Tribhuvan University)

15:30 Upgrade of beam abort system at the SuperKEKB positron ring

We upgraded the beam abort system at the SuperKEKB positron ring to speed up the abort response and mitigate the damage caused by Sudden Beam Loss (SBL). An SBL event can result in the loss of tens of percent of the beam current within one or two turns. The huge radiation accompanying the beam loss can severely damage accelerator hardware and the detectors at the interaction point. The fast-response abort sensors based on the plastic scintillator and SiPM were installed to detect the beam loss from SBL earlier. Besides, the configuration of the abort trigger system (interlock) network was customized to shorten its response. The upgrade work was conducted in the 2022-2024 long shutdown and the 2024 summer shutdown. It was implemented in the beam operation in 2024. After this upgrade, we could throw abnormal beams more than one turn earlier. It is a significant treatment against SBL. We report the details of the upgrade and the improved performance achieved in the 2024 operation.

Speaker: Hiroshi Kaji (High Energy Accelerator Research Organization)

15:30 Upgrade of IR-FEL low-level RF control system based on beam load feedforward

Hefei Infrared Free-Electron Laser device (IR-FEL) is a user experimental device dedicated to energy chemistry research that can generate high brightness mid/far infrared lasers. It is driven by an S-band linear accelerator with a maximum electron energy of 60 MeV. The stability of the final laser output is determined by the quality of the electron beam, and optimizing the Low-Level RF (LLRF) Controlsystem can elevate the beam's ultimate quality. The IR-FEL linear accelerator boasts a beam length of 13μs, exhibiting a pronounced beam loading effect. The leading edge of the beam interacts with the RF field, absorbing energy, thereby influencing the acceleration process at the beam's tail. This interaction leads to an increase in beam emittance, impacting the final laser quality. However, by incorporating a feedforward algorithm to modulate the microwave field amplitude upon the beam's arrival, we can mitigate the beam loading effect and improve beam quality. Details regarding this upgrade, along with the experimental outcomes, will be elaborated upon in the main text.

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

15:30 Upgrade of variable frequency drive for cryogenic system at NSRRC

After nearly two decades of continuous operation, the Variable Frequency Drive (VFD) of Main Cryogenic Plant 1 (MCP1) experienced a critical failure following a routine shutdown in September 2021. Despite thorough inspection and part replacement, the root cause of the failure remained elusive. Additionally, several seemingly normal spare parts were found to be damaged. Given the discontinued production of many spare parts and the presence of two identical VFDs in operation, a decision was made to upgrade the entire MCP1 VFD. After undergoing specific customizations, the new VFD was retrofitted and commenced testing in late 2021. During the dismantling process of the original VFD, the underlying cause of the failure was uncovered: a short circuit resulting from damaged power wiring. This paper delves into the distinctions between the original and new VFDs, outlines the customized modifications, and presents the comprehensive test results of the upgraded system. Furthermore, the root cause of the failure and the extent of damage inflicted by the old VFD will be discussed.

Speaker: Hsing-Chieh Li (National Synchrotron Radiation Research Center)

18:45 → 21:00 Conference Banquet

Friday 6 June

09:00 → 09:30 FRXD:Accelerator Technology and Sustainability(Invited)

Convener: Rogelio Tomas (European Organization for Nuclear Research)

09:00 Neutron target for high-intensity operation at J-PARC MLF

Neutron target for high-intensity operation at J-PARC MLF

Speaker: Katsuhiro Haga (Japan Atomic Energy Agency)

09:30 → 10:30 FRYD: Beam Dynamics and EM Fields (Invited)

Convener: Rogelio Tomas (European Organization for Nuclear Research)

09:30 Review of impedance effects for acclerators

Beam coupling impedance (in other words, wakefield) causes collective beam instabilities, heating and degradation of components due to the electromagnetic field of the beam, and beam-induced electromagnetic interference. These effects are outlined from an experimental point of view. Examples of beam ducts and kickers are mainly from J-PARC, but examples from other institutions will also be presented. Countermeasures such as kicker modifications and transverse feedback dampers will also be presented.

Speaker: Takeshi Toyama (High Energy Accelerator Research Organization)

10:00 Review of linear and nonlinear optics measurements in the CERN LHC

The LHC is approaching the end of its third operational run, with machine protection and performance having demanded an excellent control of the single-particle dynamics. Additionally, the requirement to rapidly commission multiple diverse sets of optics configurations within each year, and from year-to-year, placed clear demands on the measurement and correction methods employed. Tight tolerances on the linear optics have been consistently achieved, with the drive to ever-more pushed optics for the High Luminosity LHC era continuing to introduce new challenges. Routine control of linear coupling has been an operational necessity, while significant progress has also been made extending the understanding and control of the optics into the nonlinear regime. This paper presents the key methods used, the results obtained, and discusses the challenges to control of the beam-optics in the LHC.

Speaker: Ewen Maclean (European Organization for Nuclear Research)

10:30 → 11:00 Coffee break

11:00 → 12:30 FRZD: Friday Plenary Invited Oral

Convener: Yoichi Sato (Japan Proton Accelerator Research Complex)

11:00 Latest achievements in femtosecond synchronization of large scale facilities

The laser-based synchronisation systems for the European XFEL and FLASH provide femtosecond-stable timing references for tens of clients along the accelerator and the experiment halls over many kilometres of optical fibre. Recently, benchmarking experiments revealed a point-to-point timing stability with sub-femtosecond rms timing jitter. At the same time geophysical effects like ocean waves and earthquakes do not only affect the performance of the system, but their impact can clearly be identified. To improve the temporal resolution in X-ray/optical pump-probe experiments, additional arrival time monitors for both the electrons and the optical laser pulses are currently being installed, allowing for a posteriori data sorting and eventually active feedbacks. Further, the optical reference oscillators and advanced synchronisation schemes are being developed, resulting in timing jitter on the sub-hundred attoseconds level.

Speaker: Dr Sebastian Schulz (Deutsches Elektronen-Synchrotron DESY)

11:30 BeamPIE – a suborbital test of an accelerator for space applications

Summary: An experiment to fly an accelerator in space recently concluded successfully. Discuss the objectives, differences from terrestrial accelerators, and results from the flight.
Accelerators have the potential to play a major role in space-based activities. These can range from investigation of the Earth’s magnetic field, to helping mitigate the effects of increased solar activity (e.g. by helping drain the Earth’s radiation belts of charged particles), to deep-space missions. There are many challenges associated with operating accelerators in a space-based environment, however, ranging from high-voltage systems, to thermal management, to spacecraft charging. The Beam-Plasma Interaction Experiment – BeamPIE – was a small electron accelerator launched on a sounding rocket in 2023, to both explore the interaction of an electron beam with the near-earth plasma environment, and to test several new approaches to accelerator design in a space environment. This talk presents an overview of the BeamPIE accelerator design, mission objectives, and results from its flight.

Speaker: Quinn Marksteiner (Los Alamos National Laboratory)

12:00 Highlights from Future Circular Collider Feasibility Study and Path to Construction

The proposed Future Circular Collider (FCC) integrated programme consists of two stages: an electron–positron collider serving as a Higgs-boson, electroweak and top-quark factory,followed by a proton–proton collider operating at a collision energy around 100 TeV. In 2021, in response to the 2020 update of the European Strategy for Particle Physics, the CERN Council initiated the FCC Feasibility Study. This study covered, inter alia, physics objectives and potential, geology, civil engineering, technical infrastructure, territorial implementation, environmental aspects, R&D needs for the accelerators and detectors, socio-economic benefits, and cost. The FCC Feasibility Study was completed on 31 March 2025. We present a few key results along with accelerator R&D goals and discuss the next steps.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

12:30 → 13:10 Closing Remark

Convener: Ming-Chyuan Lin (National Synchrotron Radiation Research Center)