NAPAC25 - North American Particle Accelerator Conference 2025

10 Aug 2025, 09:00 → 15 Aug 2025, 17:00 America/Los_Angeles

SAFE Credit Union Convention Center

Roark Marsh (Lawrence Livermore National Laboratory), Tor Raubenheimer (SLAC National Accelerator Laboratory)

Welcome to the 2025 North American Particle Accelerator Conference!

We are thrilled to host NAPAC25 in the vibrant city of Sacramento, California, a place where history and innovation converge. This year, we gather at the SAFE Credit Union Convention Center, ideally situated in the heart of California's capital. Sacramento's rich heritage, coupled with its dynamic and forward-looking spirit, provides the perfect backdrop for our discussions and discoveries in particle accelerator science, technology, and engineering.

As North America's premier particle accelerator conference, NAPAC continues to offer a more intimate and focused setting compared to larger international gatherings. With around 400 participants, our conference fosters meaningful interactions, in-depth discussions, and a community atmosphere that is invaluable for advancing our field. Whether you are a seasoned researcher, an early-career professional, or a student, NAPAC25 is designed to offer something for everyone, from world-class science to specialized mini-courses.

Our venue, the SAFE Credit Union Convention Center, is not only an excellent facility for scientific exchange but is also conveniently located near many of Sacramento’s attractions. We encourage you to explore the city’s rich history, from the State Capitol to the Gold Rush-era Old Sacramento Waterfront, as well as its vibrant dining scene and cultural offerings.

We look forward to a week of insightful sessions, inspiring conversations, and valuable networking opportunities. NAPAC25 promises to be a memorable experience for all, continuing our tradition of excellence in the accelerator community.

Please join us to meet and to interact with accelerator scientists, engineers, students, decision makers, and industry experts in Sacramento!

Tor O. Raubenheimer, NAPAC’25 conference Chair,

Roark A. Marsh, Scientific Program Chair

and Local Organization Committee (Eric Prebys, UC Davis; Christine Soldahl, SLAC: Dev Soni, SLAC; Qing Ji, LBNL)

We look forward to welcoming you in Sacramento and meeting you at the conference. 

Sunday 10 August

10:00 → 10:30 Coffee

10:30 → 13:00 Sunday Tutorial

10:30 High brightness electron injectors

High-brightness electron injectors are foundational to the performance of modern particle accelerators, enabling applications from X-ray free-electron lasers to ultrafast electron diffraction and advanced accelerator concepts. This tutorial will provide an overview of the physics and design principles underlying high-brightness injectors, including photocathode radiofrequency (RF) guns, beam emittance preservation, space-charge effects, and brightness optimization strategies. We will review state-of-the-art injector technologies, diagnostic techniques, and recent advances in cathode materials and RF structures. The tutorial is aimed at graduate students, early-career researchers, and accelerator professionals seeking a deeper understanding of injector systems and their role in driving next-generation accelerator performance.

Speakers: Jared Maxson (Cornell University), Pietro Musumeci (University of California, Los Angeles)

13:00 → 14:00 Lunch

14:00 → 15:00 Poster Setup

15:00 → 18:00 Sunday Student Poster Session

15:00 2D Phase Space Tomography with SciBmad Tracking

This paper presents the application of BeamTracking.jl, a key package in the Julia based SciBmad software ecosystem for differentiable accelerator physics simulations. This study demonstrates the use of phase space tomography to reconstruct the 2D phase space distribution of a particle beam. Using the SciBmad tracking package BeamTracking.jl, the phase space distribution of the beam can be constructed from the beam’s projections after being transported through a quadrupole and a drift. This result showcases the utility of SciBmad and highlights its potential for studying and optimizing injection, transport, and beam acceleration.

Speaker: Ningdong Wang (Cornell University)

15:00 3D Theory of the Ion Channel Laser

The ion channel laser (ICL) is similar to the free electron laser (FEL) but utilizes the electric field from a blowout regime plasma wake rather than the magnetic field from an undulator to oscillate particles. Compared to the FEL, the ICL can lase with much larger energy spread beams and in much shorter distances, making it an attractive candidate for a future compact plasma accelerator driven coherent light source. We present a novel full 3D theory of the ICL accounting for numerous effects including transverse guided mode shape, diffraction, frequency and Betatron phase detuning, and nonzero spread in energy and undulator parameter. This theory is used to predict the gain, radiation mode profile, gain bandwidth, and emittance and energy spread constraints of the ion channel laser.

Speaker: Claire Hansel (University of Colorado Boulder)

15:00 A finite element study of stress reduction techniques in REBCO HTS conductor on a round cable (CORC) cable

ReBCO high-temperature superconducting (HTS) tape is critical for achieving the high magnetic fields needed in next-generation particle accelerators. Enhancing the mechanical performance of ReBCO tape increases its critical current by reducing internal stress, especially in the superconducting layer. A finite element study examined how copper layer properties affect stress in ReBCO conductor on a round core (CORC) cables. The cable was modeled as a doubly supported beam under uniform compressive stresses."cable was modeled as a doubly supported beam under uniform load to simulate bending. A staged modeling approach—from a single tape to a six-layer stack—enabled validation and efficient parameter studies. Increasing the yield strength and Young’s modulus of the copper layers reduced peak stress in the ReBCO layer. These results support development of improved tape stacks for high-field accelerator magnets

Speaker: Scott Mueller (Fermi National Accelerator Laboratory)

15:00 A Self-Supervied Transformer For RF Cavity Signal Denoising

A frequent occurrence within industrial particle accelerator systems is electromagnetic noise accumulating within RF Cavity Sensor readings, attributed to their electromagnetically dirtier operating environments and production, with less of an emphasis on their performance optimization. This phenomenon prevents signals from accurately relaying information to beam operators and specialists. Additionally, noisy signals inhibit the ability for feedback loops to meet their regulation requirements, making machine control much more difficult. Previous work has shown machine learning-based techniques as promising solutions for denoising that maintains signal quality and features. In this paper, we design, implement, and benchmark a self-supervised transformer-based machine learning algorithm that denoises In-Phase and Quadrature (I/Q) RF Cavity Signals without a need for referencing a clean ground-truth.

Speaker: Vikshar Rajesh (RadiaSoft (United States))

15:00 A W-band corrugated waveguide for high-efficiency high-gradient wakefield acceleration

Compact RF structures in the sub-terahertz regime are promising for structure wakefield acceleration due to their ability in achieving high gradients in a reduced footprint. We report on the design, fabrication, and testing of a metallic corrugated waveguide operating at 110 GHz, tailored to the 42 MeV electron beam parameters at the Argonne Wakefield Accelerator (AWA). The experiment utilized the emittance exchange (EEX) beamline at AWA for longitudinal bunch shaping in two configurations: (1) a single short drive bunch to study high decelerating gradients, and (2) a two-bunch scheme featuring a triangularly shaped drive bunch followed by a long witness bunch to probe the wakefield and achieve a high transformer ratio. We will present the experimental design and results, which show good agreement with simulation predictions.

Speaker: Brendan Leung (Northern Illinois University)

15:00 Accelerator Drift Compensation via a Modified MG-GPO Algorithm

Performance drift over long periods of operation due to changes in machines settings or the environment has been a longstanding problem for particle accelerators. Algorithms which are capable of tuning machine settings while keeping the performance within a desired threshold can be used to compensate for such drifts. We have developed a modified version of the Multi-Generation Gaussian Process Optimizer (MG-GPO) which is capable of tuning accelerator settings during user operation. The modified algorithm uses Gaussian Process regression to predict the performance of potential trial settings and removes ones with a high probability of giving too poor of a performance before selection for evaluation on the machine. The modified MG-GPO has been tested on analytic functions and applied to the SPEAR3 kicker-bump matching problem as a proof of concept. It is expected that the modified MG-GPO will be applied to maintain optimal trajectory of the beam injected into the SPEAR3 storage ring.

Speaker: Ryan Yeung (Michigan State University)

15:00 Advanced Growth and Characterization of Alkali Antimonide Photocathodes for Bright Beam Applications

The properties of the photoemitting electron sources are the most 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 letter, 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 also described in this paper.

Speaker: Tariqul Hasan (Northern Illinois University)

15:00 An electrostatic fusion collider for interstellar propulsion

In order to reach the nearest star Proxima Centauri within a century, a distance of 4.224 light-years from our solar system, the average spacecraft velocity needs to be 4.2% of the speed of light. Therefore, according to the rocket equation, the weighted average exhaust velocity needs to be over 1% of the speed of light for reasonable ratios of dry mass to fuel mass. The fusion reactor architecture presented herein consists of an electrostatic charged particle trap that brings two ion beams into collision with equal and opposite momentum. The two fusion channels under consideration for interstellar missions are p/Li7 and He3/He3, utilizing an array of low mass electrodes that minimize interactions with fusion daughters escaping from the collision point and focused to generate thrust. A prototype colliding beam accelerator has been built to determine the viability of achieving collider luminosities commensurate with the requirements of this application. A novel architecture overcomes past Coulomb scattering limitations. Reactor and propulsion system design parameters are presented in this paper along with preliminary prototype operational results with deuterium collisions.

Speaker: Ms Grace Bittlingmaier (Beam Alpha Incorporated)

15:00 Automation of sample alignment for neutron beamlines

Neutron scattering experiments are crucial for the exploration of molecular structure in compounds. The HB-2A neutron powder diffractometer at the High Flux Isotope Reactor at Oak Ridge National Laboratory conducts magnetic studies of samples by illuminating them with different energy neutron beams and recording the scattered neutrons. Proper and consistent alignment of the sample is necessary to ensure that high quality data is collected throughout an experiment. This process is currently performed manually by beamline scientists. RadiaSoft, in collaboration with the beamline scientists and engineers at ORNL, has developed a reinforcement learning-based agent capable of aligning and isolating samples. We use a Q learning structure to train the agent. The agent identifies the method to move the sample to the center of the beam and the proper amount to close the neutron camera slits. We then move the sample and close the slits using a custom Python-based EPICS IOC interfaced with the sample and slit motors. In this paper, we provide an overview of our reinforcement learning tools and show our results aligning samples like those at ORNL.

Speaker: Amelia Chen (RadiaSoft (United States))

15:00 Automation of sample identificaiton for neutron beamlines

Neutron scattering experiments are a critical tool for the investigation of molecular structure in compounds. The HB-2A neutron powder diffractometer at the High Flux Isotope Reactor at ORNL conducts magnetic studies of samples by illuminating them with different energy neutron beams and recording the scattered neutrons. Proper identification and alignment of samples during an experiment is key to ensuring high quality data is 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 software automating sample identification. We utilize a fully connected convolutional neural network configured in a U-Net architecture to identify the sample and its 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 identifying samples at ORNL.

Speaker: Amelia Chen (RadiaSoft (United States))

15:00 Bayesian Calibration of the AWA Photocathode Gun Using YAG Screen Diagnostics and OPAL Simulations

We present a data-driven characterisation of the photocathode gun at the Argonne Wakefield Accelerator (AWA) using Bayesian inference, combined with OPAL beam dynamics simulations. Our methodology employs readily available YAG screen diagnostics to perform calibration across a range of experimental conditions, including varying cathode voltages, laser profiles, and beam currents. By integrating these diagnostics with forward beam dynamics simulations from OPAL, we estimate key gun parameters, such as the gun voltage and phase from beam current and solenoid currents. Ongoing work will further refine the calibration process and explore the integration of other diagnostics to enhance the inference process. This allows for more efficient and flexible calibration of complex accelerator systems, particularly with limited readily available measurements

Speaker: Sebastian Heinekamp (Paul Scherrer Institute)

15:00 Benchmarking COMSOL and OPAL at Crocker Nuclear Lab

Accurate studies of particle behavior in accelerator chambers require precise magnetic field maps with regard to the iron geometry. We generated a realistic magnetic-field map for the 76-inch cyclotron at Crocker Nuclear Lab using COMSOL Multiphysics, then imported it into the OPAL (Object-Oriented Parallel Accelerator Library) software to model particle trajectories. It accurately simulates beam dynamics, provides reliable validation against measured data, and establishes a foundation for future cyclotron optimization and upgrades.

Speaker: SHUCHENG PAI (University of California, Davis)

15:00 Bi-Filar Coil Winding for Fast Quench Protection

The advancement of high-field magnets utilizing high-temperature superconductors (HTS) brings about complex challenges, especially in quench detection and protection. Traditional methods often fall short due to the inherently slow quench propagation in HTS materials. One promising approach to overcome this involves using a bifilar winding configuration, where two conductors are placed side by side. Under normal operation, they function in series, but during a quench event, they switch to an anti-parallel mode. This shift reduces the differential inductance of the coil to near zero, enabling rapid current oscillations through a capacitor discharge. The resulting high-frequency current flow leads to swift, uniform heating, triggering a full-coil quench within microseconds. Moreover, the strong mutual coupling between the two windings significantly reduces electrical noise in voltage measurements. In this work, we explore the viability of this concept by designing, constructing, and testing a REBCO bifilar racetrack coil in liquid nitrogen. We also present a validated simulation model that closely mirrors the coil's dynamic behavior under these conditions, aligning well with experimental observations.

Speaker: Rehan Jayathilaka (Northern Illinois University, Fermi National Accelerator Laboratory)

15:00 Co-sputter deposition of Nb₃Sn layer into SRF cavity using Nb-Sn composite target

Nb₃Sn, with its superior superconducting critical temperature (Tc ~18.3 K) and superheating field (Hsh ~400 mT), is considered a promising material for superconducting radiofrequency (SRF) cavities, offering enhanced cryogenic performance compared to bulk niobium cavities. A Nb₃Sn coating technique has been developed for Nb SRF cavities using co-sputtering of Nb-Sn composite target in a DC cylindrical magnetron sputtering system. The composite target configuration and discharge conditions for co-sputtering were optimized to deposit Nb-Sn films on flat Nb substrates, followed by annealing to form Nb₃Sn. Multiple strategies have been explored to improve the surface homogeneity of the Nb₃Sn coating, including optimizing a two-step annealing process, annealing in Sn vapor, and a light Sn recoating process. A 1.5 µm Nb-Sn co-sputtered film was deposited on the interior of a 2.6 GHz Nb SRF cavity and annealed at 600 °C for 6 h, followed by 950 °C for 1 h. Cryogenic RF testing of the annealed cavity demonstrated a Tc of 17.8 K, confirming the formation of Nb₃Sn. Then, the annealed cavity underwent a light Sn recoating treatment and attained a quality factor (Q0) of 8.5E+08 at 2.0 K.

Speaker: Md Sharifuzzaman Shakel (Old Dominion University)

15:00 Computing spin-polarization in electron storage rings by machine learning via randomized Fourier neural networks

Our work addresses the challenge of estimating spin po-
larization in high-energy electron and positron storage rings,
such as the Electron Storage Ring (ESR) of the Electron-Ion
Collider (EIC) at Brookhaven National Lab (BNL) and those
in the electron/positron Future Circular Collider (FCC-ee)
at CERN. We model the spin and orbital motion of particle
bunches using the recently introduced spin-orbit Fokker-
Planck (SOFP) equation, a linear time-evolution partial dif-
ferential equation (PDE). In this paper, we propose a novel
machine learning (ML) approach leveraging a randomized
Fourier neural network (rFNN) framework*, specifically de-
signed to solve linear PDEs. We will discuss the SOFP high-
light its relevance to spin polarization studies, and share pre-
liminary results demonstrating the network’s performance
on the Poisson problem.

Speaker: Jose Agudelo (University of New Mexico)

15:00 Data-Driven Modeling for Collider Luminosity Prediction

This work explores the application of machine learning methods to predict the luminosity of the VEPP-4M electron-positron collider. Historical data collected during operation are used to train and evaluate several machine learning models. A comparative analysis is conducted to assess the performance of different modeling approaches. The study aims to investigate whether data-driven methods can effectively capture the complex relationships between collider conditions and luminosity. The results indicate that machine learning can serve as a complementary tool for understanding and monitoring collider behavior. This approach is relevant in the context of growing interest in automation, instant diagnostics and predictive analytics in accelerator operations.

Speaker: Rasim Mamutov (Budker Institute of Nuclear Physics)

15:00 Design and cold test of a novel waveguide power splitter for distributed power coupling in short-pulse acceleration

RF breakdown is the major limitation to achieving higher accelerating gradients. Recent experimental evidence shows that this limitation can be mitigated by reducing the RF pulse length to a few nanoseconds. One key challenge in designing an accelerator operating in the short-pulse regime is achieving the required short filling time. In this work, we designed a novel waveguide power splitter to independently feed an array of accelerating cells. A prototype X-band waveguide array for a one-to-four power splitter has been developed to drive standing-wave cavities operating in the short-pulse regime. The power is designed to be equally split and fed into four cavities, with the desired phase advance per cavity. A 3D-printed prototype has been used for low-power microwave measurements ("cold" tests). The results, including measurements with a vector network analyzer and time-domain measurements, show good agreement with simulations. Ongoing work includes designing a multi-cell accelerator based on this concept for two-beam acceleration with few-nanosecond RF pulses.

Speaker: Salih Colmekci (Northern Illinois University, Argonne National Laboratory)

15:00 Design of a shipping fixture for a compact cryomodule hermetic assembly

In support of the development of a conduction-cooled 915MHz superconducting radio frequency (SRF) cryomodule, this study highlights the design of a shipping fixture for transporting the hermetic assembly 4500 km from Jefferson Lab to General Atomics in San Diego, California. The hermetic assembly consists of a 2-cell 915 MHz SRF cavity, a coaxial fundamental power coupler and warm-to-cold transition beam tubes. The two-part shipping assembly consists of an inner frame, providing direct mounting of the components, and an outer frame mounted to the ground transport vehicle. The inner frame is then connected to the outer frame by way of wire-rope isolators. Accelerometer data from ground transportation of previous projects at Jefferson Lab provides the baseline for the expected frequency and magnitude of vibrational and shock events during transit. Modal analyses were carried out in ANSYS on the inner frame assembly and critical components to identify an appropriate wire-rope isolator configuration such that peak loads are mitigated and the incurred frequencies do not correspond with the fundamental modes of the structures.

Speaker: Jacob Lewis (Old Dominion University)

15:00 DESIGN OF AN OPTICAL AMPLIFIER FOR AMPLIFIED OSC IN IOTA FACILITY AT FERMILAB

Optical stochastic cooling (OSC) is a cutting-edge beam cooling technology to reduce, control the 3 dimensional spread and the motion of particle beams. It has recently been successfully, experimentally, demonstrated in Fermilab's IOTA storage ring, marking a major step forward in beam cooling. OSC has the potential to significantly improve both the performance and flexibility as a beam cooling system. One promising way to boost OSC performance is by adding a high-gain optical amplifier. However, this amplifier must be carefully designed to meet the specific constraints of the OSC system. A major challenge lies in the limited optical delay, which is just 6 mm for the case of IOTA, set by the beam bypass, restricts us to use a short-length gain medium. This, along with IOTA’s high repetition rate and the relatively long duration of the optical pulses, limits the peak power available for the pump laser without damaging the crystal, which is crucial for achieving strong nonlinear gain. Additionally, it's essential to preserve the phase coherence of the undulator radiation during amplification, which further complicates the amplifier design. This report details a specialized amplifier setup that addresses these challenges, includes simulations of the integrated system, and summarizes the latest experimental progress and results.

Speaker: Abhishek Mondal (Fermi National Accelerator Laboratory)

15:00 Design of phase diversity Electro-Optic Sampling of THz Coherent Transition Radiation

We report progress on the design of a Phase Diversity Electro-Optic Sampling (DEOS)-based longitudinal profile measurement system. The current design uses THz coherent transition radiation (CTR) to convey the bunch’s longitudinal information. A 1550nm fiber laser available at the Argonne Wakefield Accelerator facility will be used as the probe for electro-optic sampling. Specifically, we discuss pulse synchronization and probe beam transport, the design and optimization of the probe beam stretcher, and the design of the probe beam detection system.

Speaker: Spencer Kelham (Northern Illinois University)

15:00 Design study of an RF-Kicker module for bunch cleaning at the ATLAS Positive-Ion Injector.

Positive-Ion Injector at ATLAS accelerator facility can accelerate heavy ions and has three key subsystems -- an electron cyclotron resonance (ECR) ion source, a 12-MHz multi-stage beam bunching system, and a 12-MV superconducting linac accelerator. The first stage of the bunching system is a multi-harmonic buncher that operates at 12.125 MHz and creates a bunch train with a period of 82.5 ns at ~70% bunching efficiency. The remaining unbunched beam must be removed to avoid the production of undesirable ‘satellite’ bunches, which can quench the superconducting solenoids downstream during operation. In this paper, we present the design of a resonant sine-wave RF-structure that effectively removes the bunch ‘tails’ using a vertically deflecting kick. We also discuss the effects of the RF-Kicker on the beam quality, which was estimated by TRACK3D simulations.

Speaker: Deeksha Sinha (Northern Illinois University)

15:00 Development of a Density Functional Theory Approach for Calculating Electronic Band Structure Parameters in Support of Monte Carlo Simulations of Photoemission

Monte Carlo simulations are a powerful tool for modeling photoemission from photocathodes, enabling the prediction of key parameters such as quantum efficiency, mean transverse energy, electron spin polarization, and photocathode response time. However, these simulations require material band structure parameters, which are not always available from experiments. This work aims to establish a reliable framework for calculating electronic band structure parameters using Density Functional Theory (DFT). Specifically, we apply this framework to investigate the effects of lattice strain and temperature on the electronic band structure and electron transport in GaAs. This approach will be further extended to explore band structure modifications in heavily p-doped semiconductors and to calculate electronic band structures of novel spin-polarized photocathode materials.

Speaker: Joniel Mendez (Northern Illinois University)

15:00 Developments in Lume-ACE3P Including S-Parameter Optimization for S3P

We present here the introduction of optimization to LUME-ACE3P (LUME: Lightsource Unified Modeling Environment; ACE3P: Advanced Computational Electromagnetics 3D Parallel). LUME-ACE3P is a Python wrapper that streamlines workflows for ACE3P, a suite of finite element solvers for electromagnetic fields in complex geometries. LUME-ACE3P offers parameter sweep capabilities, which was previously the only means to perform optimization with this code. In the integration of LUME-ACE3P with the optimization package Xopt, we facilitate efficient and easy to use optimization for accelerator component design. We present the LUME-ACE3P-Xopt workflow with an example problem.

Speaker: Lila Fowler (SLAC National Accelerator Laboratory)

15:00 Effects of Beam Conditions on Achieving Compact Longitudinal De-chirping Using Transverse Deflecting Cavities

It has been shown that a transverse deflecting cavity (TDC)-based de-chirper can be made by altering the drift sections in a TDC-based chirper to form negative drifts. While five appropriately configured quadrupole magnets can implement such negative drifts, this approach is limited by spatial and experimental constraints. In this study, we investigate an alternative configuration that uses three quadrupole magnets to form a negative identity transport section between the TDCs instead of a negative drift. To assess the robustness of this proposed design, a computational study has been conducted on initial beam conditions to determine the operational limitations. This includes the effects of space charge and initial transverse beam conditions, such as beam size and divergence, on the resulting transverse emittance.

Speaker: Alex DeSimone (Northern Illinois University)

15:00 Efficient phase space density construction via transfer operators

Optimizing accelerator lattices requires evaluating phase space densities through extended or repeated particle-in-cell simulations. These are computationally expensive due to the need to solve the equations of motion for large numbers of charged particles in prescribed and self-consistent fields. We introduce a method that significantly reduces the computational burden by constructing approximate invariant densities via a two-step transfer operator approach. The method gives practical approximations to phase-space level curves, capturing essential dynamics without extensive particle pushing. Prior work has shown how to find such curves via kernel-based level set learning. Our method is fast, avoids kernel tuning, and integrates with existing codes, enabling rapid assessment of figures of merit in constrained optimization algorithms such as Adjoint with a Chaser, AWC*. AWC efficiently computes gradients with respect to lattice parameters while preserving moment periodicity and accounting for self-fields and collective effects. We present results demonstrating accuracy, speed-up, and trade-offs between precision and computational cost in lattice design.

Speaker: Vincent Tembo (University of Maryland, College Park)

15:00 Electro-Optic Sampling Beam Positioning Monitor for Relativistic Electron Beams

Non-destructive diagnostics able to resolve transverse offsets and longitudinal separation of ultra-relativistic, two-bunch electron beams are necessary for a variety of applications including the ion channel laser (ICL) and other plasma wakefield (PWFA) experiments. A prototype electro-optic beam positioning monitor (EOS-BPM) utilizing two independent laser pulses traveling through a pair of EO crystals has been installed at the SLAC National Accelerator Laboratory FACET-II facility. This system is capable of order 10 fs temporal resolution and order 100 µm transverse position resolution. To achieve better transverse resolution we introduce a new design using an axicon lens to create a donut beam and a multi-crystal structure placed around the axis of propagation of the electron beam. Experimental results of the prototype EOS-BPM along with the simulated response of the new EOS-BPM design to the ultra-relativistic, two-bunch electron beam used for PWFA experiments at FACET-II will be presented.

Speaker: Elena Ros (University of Colorado Boulder)

15:00 Evolution of Realistic Beam Distributions in Space-Charge-Dominated Electron Beams

Idealized models predict beam moments and envelopes, but not the detailed beam structure within those envelopes. We explore in experiment and simulation the interplay of space charge and angular momentum with realistic beam distributions in a low-energy transport system. Our realistic phase space distributions derive from direct experimental measurements near the beam source. The platform for this work is our Long Solenoid Experiment (LSE), a beam line designed to explore flat-to-round (FTR) and round-to-flat (RTF) beam transformations where space charge is a significant factor. Our transport system employs a thermionic electron gun, a slit mask, and skew quadruples to generate and manipulate flat beams with emittance ratios up to 20:1. The LSE is equipped with a sliding view-screen, enabling detailed phase space diagnostics over multiple plasma periods. We present simulations, initialized with realistic phase space distributions and validated against experimental results, that reveal the sensitivities of transverse beam dynamics to specific initial conditions and lattice parameters.

Speaker: Shiyi Wang (University of Maryland, College Park)

15:00 Experimental longitudinal emittance manipulation using laser-based photoionization in the Fermilab Linac

A series of simulations and beam studies were conducted at Fermilab’s linear accelerator to evaluate the effectiveness of longitudinal emittance control via laser-induced photoionization. While similar laser techniques have been employed at Fermilab to enhance injection and extraction efficiency into the Booster, the work presented here focuses on extending these methods to bunch-by-bunch manipulation. This approach utilizes fine-scale correction of the H- bunches’ longitudinal spatial distribution. In theory, loosely confined particles in longitudinal phase space contribute to emittance growth during acceleration. By selectively removing these outlying particles through laser scraping (H- + γ → H + e-), this growth can be reduced. This report presents experimental results from both symmetric and asymmetric longitudinal scraping of H⁻ bunches in the Fermilab linac, which were subsequently injected into Booster, and evaluates the broader applicability of this method for future high-intensity accelerator operations.

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

15:00 External controller for the SRFK thyratron heaters

The following work will detail the development and implementation of a system which will measure the voltage and current from two points on a high-voltage switch called a thyratron and automatically manipulate two variable transformers controlling these values. Each of the extraction kickers at LANSCE (SRFK71 & SRFK81) uses a thyratron to trigger their respective pulses. The thyratrons have separate heaters for the cathode and reservoir, and each needs to maintain specific voltage and current levels for the thyratron to work properly. Currently, the method of measuring and adjusting these values requires locking out the system, opening the tank, and measuring the voltage and current of each heater, then adjusting two variable transformers by hand to reach the desired values. This controller consists of four analog-to-digital converters which will relay these measurements out of the modulator as digital signals through fiber optic transceivers. An Arduino will be programmed to interpret the digital signals and display the values on an LCD. It will also return signals to DC motors controlling the variable transformers if the values lie beyond the desired range.

Speaker: Benjamin Laurel (Los Alamos National Laboratory)

15:00 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, and data measured from beam tests. 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.

Speaker: Ryan Hensley (University of California, Davis)

15:00 Extracting symplectic maps for space charge dominated beams

Symplecticity of 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)

15:00 Fast Beam Probe Development for Longitudinal Bunch Measurements at UC Davis Crocker Nuclear Laboratory Cyclotron

The UC Davis Crocker Nuclear Laboratory (CNL) operates a 76-inch Isochronous Cyclotron dating to the 1960s. Recent experiments have revealed unexplained beam behavior, which cannot be directly measured with the current diagnostics. Direct measurements of the beam in the Cyclotron are challenging due to the harsh environment, including high radiation, strong magnetic fields, RF interference, and spatial constraints. To address this, we are developing a novel beam probe capable of resolving longitudinal bunch structure across 16 positions simultaneously. The fast beam probe consists of a segmented fast plastic scintillator array coupled via fiber optics to external Silicon Photomultipliers (SiPMs), mounted on a radially translating probe. We report on the probe's performance from in-air tests at the general-purpose beamline. The results demonstrate sub-nanosecond resolution, consistent sensitivity across channels, and clear signatures of beam dynamics, establishing the system’s viability for measurements inside the CNL Cyclotron.

Speaker: Logan Knudson (University of California, Davis)

15:00 Flat beam PWFA theory and experiment at AWA

A wakefield experiment at the Argonne Wakefield Accelerator (AWA) facility utilizes flat electron beams with highly asymmetric transverse emittances to drive plasma wakefields in the underdense regime. These beams create elliptical blowout structures, producing asymmetric transverse focusing forces. The experiment utilizes a compact 4-cm-long capillary discharge plasma source developed at UCLA. Analytic models of blowout ellipticity and matching conditions, supported by particle-in-cell simulations, guide the experiment's design. Engineering preparations including the use of windows for vacuum-gas separation, beam transport and diagnostics are discussed along with the first beam runs which involve flat beam generation and transport. The theory of flat beam plasma wakefield interaction will also be discussed

Speaker: Pratik Manwani (University of California, Los Angeles)

15:00 Halo Formation in High-Intensity Linacs: Modeling and Advanced Phase Space Diagnostics

Work at the SNS Beam Test Facility aims to characterize halo formation in the early stages of a high-power linac and to reproduce halo measurements with well-benchmarked particle-in-cell simulations. The BTF is equipped with advanced phase space diagnostics that enable detailed characterization of beam distributions at the beginning and end of a 2.5 MeV, 10 meter test beamline. Diagnostic capabilities include direct measurement of the 6D phase space distribution, as well as imaging of 2D phase space projections with 6 orders of magnitude in dynamic range. This talk will compare predictions from the PyORBIT code to measured distributions, as well as discuss the parameters and limitations of the simulation model.

Speaker: Trent Thompson (Oak Ridge National Laboratory)

15:00 Instability Threshold Measurements in the IOTA Ring at Fermilab

Nonlinear focusing elements enhance the stability of particle beams in high-energy colliders via Landau Damping, a phenomenon that acts through the tune spread these elements introduce. This experiment at Fermilab's Integrable Optics Test Accelerator (IOTA) aims to investigate the influence of nonlinear focusing elements on transverse beam stability by employing a novel method to directly measure the strength of Landau Damping. This method employs an active transverse feedback system as a controlled source of impedance to induce a coherent beam instability. The beam’s resulting growth rate and transverse feedback parameters can then be used to directly measure the stability diagram, a threshold which maps the system's stability conditions. A proof-of-principle experiment of this measurement method was first explored at the LHC, where the experiment at IOTA aims to map out the entirety of the stability diagram and to obtain the beam distribution function from the stability diagram, a procedure never done before that would enable one to obtain the beam distribution tails. Here we present the initial results of stability diagram data analysis, simulation results, and plans for further investigation.

Speaker: Mary Duncan (University of Chicago)

15:00 Integral Field Probe for Mapping of Curved Magnets

The Single Stretched Wire (SSW) method allows highly precise integral field measurements by recording voltage across a tensioned wire mounted to 2-axis linear stages at either end of the magnet aperture. However, traditional SSW probes are not well suited for curved accelerator magnets, which are essential for steering charged particles along arced trajectories in storage rings or beamlines. The tension required to eliminate sag demands a purely straight path, making them incompatible with non-linear magnet geometries. To address this limitation for curved magnets, a modified approach was developed using a segmented, 3D-printed support structure that incorporates a pre-shaped “anti-sag” curve. Under its own weight and that of the wire bundle, the structure deforms to lie flat while conforming to the curvature of the magnet in the horizontal plane. The optimal geometry of the probe was derived using an iterative process combining FEA simulations in Ansys Mechanical with testing of various carbon fiber-reinforced filaments. The printed and assembled probe was successfully used to measure the SDD-055 magnet at Fermilab, yielding promising results.

Speaker: Alexander Jakopin (Northern Illinois University)

15:00 Investigating Dirac semimetal cadmium arsenide as a potential low-MTE photocathode

We report on the quantum efficiency (QE) and mean transverse energy (MTE) of photoemitted electrons from cadmium arsenide (Cd₃As₂), a three-dimensional Dirac semimetal (3D DSM) of interest for photocathode applications due to its unique electronic band structure, characterized by a 3D linear dispersion relation at the Fermi energy. Samples were synthesized at the National Renewable Energy Laboratory (NREL) and transferred under ultra-high vacuum to Arizona State University (ASU) for measurement using a photoemission electron microscope (PEEM). The maximum QE was measured to be 3.37 × 10^-4 at 230 nm, and the minimum MTE was 55.8 meV at 250 nm. These findings represent the first reported QE and MTE measurements of Cd₃As₂ and are an important step in evaluating the viability of 3D DSMs as low-MTE photocathodes. Such photocathodes, constrained to lower MTEs by the electronic band structure, may prove effective in advancing beam brightness in next-generation instruments and techniques.

Speaker: Truman Idso (Arizona State University)

15:00 Investigation of Wakefields in Dielectric Structures with Different Cross Sections

Dielectric-lined waveguides are a promising platform for high-gradient beam-driven dielectric wakefield acceleration (DWFA). We present experimental results from a recent study at the Argonne Wakefield Accelerator (AWA), focusing on the performance of three copper-coated dielectric structures with distinct cross-sections: circular, rectangular, and square. These geometries enable a comparative evaluation of the accelerating gradients and wakefield characteristics supported by each configuration. A key feature of this experiment is the use of a "loading bunch" to suppress the wakefield, demonstrating active control of energy transfer along the beam path. To directly measure wakefield suppression, a circular structure with an angled downstream cut was used to redirect coherent Cherenkov radiation into an autocorrelator for temporal diagnostics. Accelerating gradients were measured using a single-shot longitudinal phase space diagnostic, providing insight into geometry-dependent wakefield behavior. These results support future structure optimization efforts and advance experimental techniques for wakefield control in dielectric-based acceleration.

Speaker: Calcifer Phillips (Northern Illinois University)

15:00 IOTA Experiment for Proton Pulse Compression at Extreme Space-Charge

The longitudinal compression of intense proton bunches with strong space-charge force is an essential component of a proton driver for a muon collider. We propose a proton bunch compression experiment at the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab to explore optimal radio frequency (RF) cavity and lattice configurations. IOTA is a compact fixed-energy storage ring dedicated to beam physics R&D that can circulate a 2.5-MeV proton beam with extreme space-charge. Using ImpactX and its 3D space-charge solver, simulations indicate that bunch length can be rapidly reduced by a factor of at least two, without appreciable degradation in transverse beam quality, even under strong space-charge conditions. However, longitudinal defocusing presents a large effect in short-pulsed proton beams, and the optimization of bunch compression under such conditions is discussed.

Speaker: Benjamin Simons (Northern Illinois University, Fermi National Accelerator Laboratory)

15:00 Laser-Ionized Plasma Sources for Plasma Wakefield Accelerators: Alignment Technique, Tolerance, and Applications

Plasma wakefield accelerators (PWFA) are promising candidates for next-generation colliders due to their ability to sustain extremely high acceleration gradients. Laser-ionized plasma sources offer key advantages for PWFA, including precise control over the transverse and longitudinal plasma density profiles for emittance preservation, tunable plasma column widths suited for positron acceleration, and resilience to heat deposition. A critical experimental challenge, however, is the precise alignment of the plasma source to the electron beam and maintaining that alignment over time. We report on a novel alignment technique developed at the Facility for Advanced Accelerator Experimental Tests II (FACET-II), enabling high-precision alignment of a 1-meter-long laser-ionized plasma source to a 10 GeV, 1.6 nC electron beam with a transverse accuracy better than 10 µm, limited primarily by laser pointing jitter. We present our methodology, discuss the alignment tolerances between the drive beam and the laser-ionized plasma, and explore future opportunities for using narrow plasma columns for positron acceleration.

Speaker: Valentina Lee (University of Colorado Boulder)

15:00 Lattice refinements for nonlinear integrable optics in IOTA

Nonlinear integrable optics of the type proposed by Danilov and Nagaitsev place strict constraints on the lattice parameters in the matching section outside of the nonlinear insert. In particular, the effects of energy spread in the beam have significant effects on the stability of the system. Typical chromatic compensation using sexupoles has significant perturbative effects on the dynamics and fails to address the variation in the lattice due to low order effects of the nonlinear insert. Refinements to the IOTA lattice parameters based on experience with electron beam operation are presented.

Speaker: John Wieland (Fermi National Accelerator Laboratory)

15:00 Leveraging the capabilities of LCLS-II: linking adaptable photoinjector laser shaping to tailored X-ray production

SLAC’s LCLS-II is pioneering high-repetition-rate attosecond X-ray science, enabling new opportunities to optimize X-ray generation by controlling the electron beam at its source—the photoinjector. LCLS-II employs a 20 ps Gaussian UV laser pulse to drive the photocathode, with an added narrow modulation to induce microbunching for extended modes. Recent advances in laser pulse shaping and frequency upconversion now allow for more sophisticated tailoring of the electron beam at the injector.
We present a novel approach using spectral amplitude and phase shaping of the IR laser, followed by dispersion-controlled nonlinear synthesis—relying on phase-modulated noncollinear sum-frequency generation—for UV upconversion. This enables diverse UV temporal profiles, including flattop and double/triple spikes, offering new degrees of freedom for shaping. Preliminary results from LCLS-II beam time show these modulations produce effective downstream perturbations to the electron bunch at the undulators, demonstrating feasibility for programmable bunch formation.
We are integrating this shaping into a start-to-end simulation framework,** enabling digital twin modeling of the XFEL chain—from photoinjector laser to X-ray output—laying the groundwork for fully tunable, end-to-end optimized, application-specific X-ray pulses.

Speaker: Jack Hirschman (Stanford University)

15:00 Light-Induced Enhancement of Quantum Efficiency in III-Nitride Photocathodes

" High quantum efficiency (QE) semiconductor photocathodes are essential for generating high average beam current and brightness. One class of semiconductor photocathodes considered for use in photoinjectors for unpolarized and polarized electron beams are III-nitride heterostructures. These materials can exhibit negative electron affinity at the surface, utilizing intrinsic polarization fields to engineer the band structure without the need for additional surface treatments. In this study, we investigate the effects of light exposure on the surface of III-nitride photocathodes and the resulting changes in QE and photoemission, using photoemission electron microscopy (PEEM) for characterization. We demonstrate that exposing a GaN photocathode to a 240 nm wavelength laser at 870 µW for 15 minutes increases the QE by two orders of magnitude, with a maximum QE of 2.34 × 10⁻⁴ observed. Although III-nitride photocathodes are known for their robustness, our findings indicate that laser exposure can significantly alter their QE. Our observations reveal the need for a detailed investigation of photo-induced effects on QE in III-Nitride photocathodes."

Speaker: Mansoure Moeini Rizi (Arizona State University)

15:00 Machine Learning-Enhanced Deterministic Controls in Lasers and Accelerators

Lasers and accelerators are inherently complex systems, often requiring multi-input multi-output (MIMO) control strategies with demanding requirements on precision, speed, and scalability. As these systems push toward more stringent performance goals, traditional control techniques often face limitations in responsiveness and robustness.

In this talk, I will discuss how we’ve begun incorporating machine learning (ML) into feedback control loops to address some of these challenges. When integrated thoughtfully, ML models can provide fast, data-driven predictions and decisions that enhance control performance, particularly in complex environments.

I will highlight several examples where ML has contributed to improved outcomes. At LBNL, ML-based feedback reduced the response time of complex laser combining systems by nearly an order of magnitude. On the BELLA Petawatt beamline, we performed the first experimental demonstration of ML-driven shot-to-shot laser pointing stabilization, addressing bandwidth limits in conventional control systems. We’ve also developed lightweight reinforcement learning algorithms for various control scenarios and begun implementing ML models on FPGAs for real-time MIMO control.

These efforts are still ongoing, but suggest that ML can be a valuable and practical addition to modern control systems—offering improved precision, adaptability, and speed in demanding laser and accelerator environments.

Speaker: Dan Wang (Lawrence Berkeley National Laboratory)

15:00 Matching the Beam from AGS to the EIC Hadron Storage Ring with Excellent Emittance Preservation

The Electron-Ion Collider (EIC), a next-generation accelerator facility, is being jointly developed by Brookhaven National Laboratory (BNL) and Jefferson Lab (JLab), and will be constructed at BNL. The EIC design builds upon the existing RHIC heavy-ion infrastructure, transforming the RHIC rings into the Hadron Storage Ring (HSR) with necessary modifications. To ensure optimal performance, it is critical to accurately match the beam from the injectors to the HSR in six-dimensional phase space, in addition to the match of positions and angles. Inadequate matching can lead to emittance growth, which negatively impacts the achievable luminosity of the collider. This report outlines the key constraints involved in the matching process and presents a systematic approach to achieving high-fidelity beam matching while preserving emittance quality.

Speaker: Anbang Jiang (Ward Melville High School)

15:00 Measurements of single-shot attosecond X-ray pulses at high repetition rate

Electron dynamics in molecules occur on attosecond timescales and drive fundamental processes such as photosynthesis, catalysis, and chemical bond transformations. Understanding these phenomena requires tools with both high temporal resolution and the capability to probe molecular dynamics at high repetition rates. Here, we present the first single-shot measurements of attosecond soft x-ray pulses at the superconducting LCLS-II accelerator. Using an angle-resolving electron time-of-flight spectrometer, we perform angular streaking measurements with high energy and angular resolution, enabling a complete reconstruction of the spatial and temporal profiles of the pulses. These measurements showcase the attosecond science capabilities of LCLS-II at unprecedented repetition rates and provide the foundation for controlling and shaping x-ray pulses to study ultrafast dynamics in complex systems with precision.

Speaker: Veronica Guo (Stanford University)

15:00 Minimizing dispersion through resonant extraction for BNL's NSRL

Simulations, analysis, and measurements are performed on the BNL Booster’s third integer resonance extraction to the NSRL line, which uses a constant optics slow extraction method. In this method, ring dipoles and quadrupoles are changed synchronously for a coasting beam, which aids in maintaining a fixed separatrix orientation through the spill. Simulations show that the outgoing beam has a very small dispersion, independent of the periodic dispersion value at the septum. We show using a first-order normal form approximation that transforms to the Kobayashi Hamiltonian, how the dynamics of such a spill lead to a dispersion-free outgoing beam, which is critical to the uniformity requirements of the NSRL. Finally, we measure the dispersion of the beam by varying the flattop energy of the coasting beam in the booster before engaging the spill and show that the magnitude of dispersion is reduced by over a factor of 5 from the periodic value in the ring.

Speaker: Eiad Hamwi (Cornell University)

15:00 Mu2e Resonant Extraction Regulation System Simulation in Delivery Ring

Mu2e is an upcoming experiment at Fermilab that relies on the slowly extracted 8 GeV proton beam from the Delivery Ring. The experiment imposes strong requirements on the spill uniformity. To address these requirements, the fast spill regulations system is being developed and commissioned. To inform this development and optimize the system performance we are carrying out the detailed simulations of the regulation process. The simulation includes the effect of six harmonic sextupoles that excite the third-integer resonance and three fast ramping quadrupoles that drive the horizontal tune to 29/3. The components of spill regulation system are designed to mitigate long-term drifts in the beam, ensuring stable operation over extended timescales, as well as addresses rapid variations within single spill. In this study, we review the regulation system design, simulation of the slow regulation, and the fast regulation PID regulation to curtail random variations in the extraction rate that could occur within a single spill.

Speaker: Aakaash Narayanan (Fermi National Accelerator Laboratory)

15:00 Multi-objective optimization of strong hadron cooler Energy Recovery Linac injector

The Strong Hadron Cooler (SHC) proposed for the Electron-Ion Collider (EIC) requires high-current, low-emittance electron bunches with minimal energy spread. The Energy Recovery Linac (ERL) injector plays a critical role in shaping the beam before acceleration. We present a multi-objective optimization study of the SHC ERL injector and merger using space charge tracking in Bmad and parallel genetic algorithm. The optimized configuration reduces the normalized transverse emittance by 62% and energy spread by 85% from the original configuration.

Speaker: Ningdong Wang (Cornell University)

15:00 Nested Extremum Seeking for Virtual Diagnostics and Control

Machine learning methods have been increasingly used to model complex physical processes that are difficult to address with traditional approaches, especially when these processes exhibit temporal dynamics or require real-time implementation. The linear accelerator (LINAC) at the LANSCE facility is one such system. While a high-resolution simulation tool, HPSim, exists, the complexity and high computational costs of the simulation, combined with the spatiotemporal variability of the LINAC and limited diagnostic measurements, creates challenges for real-time operation. These challenges can be mitigated by developing fast surrogate machine learning models to provide virtual diagnostics and enable control. However, the highly expressive nature of machine learning models often results in opaque representations, complicating their use in control applications. Control design and tuning are significantly simplified when the system dynamics are captured by a more interpretable, parsimonious model. This study seeks to harness the power of machine learning while applying traditional system identification techniques to develop models that are both effective for control and computationally efficient.

Speaker: Brad Ratto (Los Alamos National Laboratory)

15:00 One-to-one mapping between the electromagnetic modes of Cylindrical and Coaxial Half-wave cavities

Design of radio frequency (RF) couplers and diagnostics require a good understanding of the electromagnetic mode patterns of RF cavities. This study investigates the adiabatic transformation of transverse magnetic (TM) modes in a cylindrical cavity into transverse electromagnetic (TEM) modes of a coaxial cavity by gradually introducing an inner conductor. Using CST Studio Suite, we simulate the eigenmode evolution as the geometry transforms from a pure cylindrical to a coaxial configuration. We track the behavior of TM010 through TM014 modes to observe the continuous evolution into the corresponding TEM0 through TEM4 modes of the coaxial cavity. The process is governed by the evolution of the electric field orientation as the geometry shifts, enabling the axial TM fields to reorient into the radial electric field configuration of TEM modes. Field patterns, eigen-frequencies, and mode indentities are analyzed throughtout the transition. The results provide simulation-based evidence that TM to TEM conversion occurs without generation of newer eigenmodes, offering a valuable insight into the design of transition regions in superconducting RF (SRF) systems and provides a foundation for experimental validation.

Speaker: Fariha Ahmed (Old Dominion University, Thomas Jefferson National Accelerator Facility)

15:00 Optimizing 4D emittance measurements using the pinhole scan technique

Accurate measurement of electron beam emittance is essential for optimizing high-brightness electron sources. The Pinhole Scan Technique measures the 4D phase space and hence the emittance by measuring the beam profile after clipping the beam using a pinhole followed by a drift section and then scanning the beam over the pinhole. This technique has been implemented in low (< 200 keV) beamlines at both Cornell university and Arizona State University. However, the technique poses several practical challenges. In this work, we analyze and address key issues affecting the 4D phase space and emittance measurements using this technique. We identify and investigate sources of inaccuracies like the pinhole aspect ratio, beam divergence, position-momentum correlations in the phase space, and the point-spread-function of the detector and suggest techniques to minimize them. Our findings offer a pathway to more accurate 4D phase space characterization in advanced electron beam systems.

Speaker: Peter Owusu (Arizona State University)

15:00 Passive plasma lens experiments at FACET-II

The beam-driven, passive plasma lens can provide axisymmetric focusing with strengths orders of magnitude greater than conventional quadrupole magnets, while remaining ultra-compact. These characteristics make it attractive for beam matching into a plasma wakefield accelerator and for controlling beam divergence downstream of plasma stages. Optimal performance can be achieved in the underdense regime, resulting in a linear focusing force and emittance preservation of the focused beam. We report progress on experimental results from SLAC’s FACET-II facility, where we utilized a fs Ti:Sapphire laser pulse to ionize hydrogen gas from a supersonic gas jet to focus several hundred pCs of charge of a 10 GeV electron beam.

Speaker: Mr Shutang Meng (University of Colorado Boulder)

15:00 Phase space reconstruction of beams affected by coherent synchrotron radiation

Coherent synchrotron radiation (CSR) is a limiting effect in linear accelerators with dispersive elements due to its contribution to projected transverse emittance growth. This effect becomes a limitation for highly compressed beams. Even though CSR-induced projected emittance growth has been widely studied, conventional measurement techniques are not detailed enough to resolve the multi-dimensional structure of the beam, namely the different translations and rotations of transverse phase space slices throughout the longitudinal coordinate. In this work, we use a state-of-the-art method to reconstruct the phase space of a beam affected by CSR at the Argonne Wakefield Accelerator Facility. This detailed, efficient and multi-dimensional phase space reconstruction method enables better understanding of the CSR effects in a double dogleg where shielding is limited.

Speaker: Juan Pablo Gonzalez-Aguilera (University of Chicago)

15:00 Phase Space Tomography at FACET-II

We present recent development of transverse phase space tomographic reconstruction techniques at FACET-II. We present implementation of such techniques in the FACET-II injector, and utilize it to characterize the two-bunch from photocathode configurations. We demonstrate the characterization of two-bunch phase space misalignment and its potential control and application in PWFA experiments. We also characterize the effect of transverse space-charge force by varying two-bunch charge ratio. We also present single-shot and multi-shot tomographic reconstruction of electron spectroscopy image for PWFA-accelerated beam characterization.

Speaker: Yiheng Ye (SLAC National Accelerator Laboratory)

15:00 Physics Model to Study Resonant Compton Scattering

Over the past several decades, the elastic interaction between photons and electrons known as Compton scattering, has been the foundational mechanism for generating high-energy photon beams, particularly in the gamma-ray regime. Resonant interactions between photons and atomic systems offer significantly enhanced resonant cross-sections, often several orders of magnitude greater than what is achievable through conventional Compton scattering of electron and photon beams. The Gamma Factory initiative at CERN aims to exploit this enhancement by employing ultra-relativistic, partially stripped ion beams to generate high-intensity gamma-ray beams. In this work, we first examine the energy-matching requirements for resonance. We then present a semi-classical model based on a damped-driven oscillator to describe resonant Compton scattering. This model provides physical insight into the resonant cross-section and the limitations imposed by beam-beam interactions. We also propose a framework for simulating the scattering process.

Speaker: William Delooze (Duke University)

15:00 Picometer-scale emittance and space charge effects in nanostructured photocathodes.

Generation of ultralow-emittance electron beams with high brightness is critical for several applications such as ultrafast electron diffraction, microscopy, and advanced accelerator techniques. By leveraging the differences in work function and electronic structure between different materials, we enabled spatially localized photoemission, resulting in picometer-scale emittance from a flat photocathode. We also investigated space charge effects by measuring how the emission spot size, as measured in a photoemission electron microscope, changes with the number of electrons emitted per laser pulse. When more than one electron is emitted simultaneously, Coulomb repulsion causes a substantial broadening of the observed source size, enabling us to investigate the limitations imposed by vacuum space charge forces during pulsed photoemission. Our results highlight the potential of nanoscale photoemitters as high-brightness electron sources and offer new insights into electron correlations that emerge after ultrafast photoemission.

Speaker: Anagha Ullattuparambil (Arizona State University)

15:00 Plasma Waves in Accelerators

This work presents new insights into the formation and propagation of solitons in the University of Maryland Electron Ring (UMER), using a combination of theory, Particle-In-Cell (PIC) simulation, and experimental validation. Soliton dynamics in the electron beam are modeled via the Korteweg–de Vries (KdV) equation, capturing the balance between nonlinearity and dispersion inherent in space-charge-dominated beams confined within a conducting beam pipe.
We report the first-ever characterization of dark (negative) solitons in an accelerator, emerging from negative perturbations in a regime of negative dispersion. We also report observing oscillatory wave structures from the KdV equation for the first time in an accelerator, arising from negative beam perturbations in a positive dispersion regime. These results provide a unique platform for both exploring beam manipulation using soliton-based mechanisms, and for exploring fundamental nonlinear wave dynamics relevant to other complex environments such as space plasmas.

Speaker: Hannah McCright (University of Maryland, College Park)

15:00 Preliminary computational study on minimizing longitudinal emittance in photoinjector

Recently, we proposed a novel photoinjector that incorporates an emittance exchange (EEX) beamline. Previous studies demonstrated promising 4D emittance performance of an EEX-based injector, but the beam’s longitudinal emittance at the linac exit still limits the final transverse emittance downstream of the EEX stage. We performed a comprehensive scan of injector parameters—including gun phase, laser spot size and pulse length, and solenoid strengths—to (1) estimate the minimum achievable longitudinal emittance, (2) identify sources of emittance growth, and (3) explore mitigation strategies. Here, we present the status of this study. Simulations were carried out using General Particle Tracer (GPT) including space-charge effects.

Speaker: MinKyu Seo (Korea University Sejong Campus)

15:00 Preliminary study of Auto-differentiation algorithm in Beam Dynamics with Stochastic process

Modern particle accelerator optimization requires sophisticated computational methods to address the inherently stochastic nature of beam dynamics. This research develops a framework applying AD to SDEs that specifically addresses beam dynamics challenges in particle accelerators, focusing on accurately modeling and optimizing beam behavior in regimes dominated by stochastic processes. By incorporating key physical phenomena such as synchrotron radiation, wakefield effects, and quantum excitation, the framework aims to provide auto differentiation on the figure of merit of the phase space evolution and beam dynamics. The methodology will enable effective optimization method in a dynamic system with stochastic process.

Speaker: Christian Ratcliff (Facility for Rare Isotope Beams)

15:00 Preliminary study of space charge and beam-beam interplay in a collider ring

Hadron Collider Rings offer unprecedented opportunities to address fundamental scientific questions in particle and nuclear physics. To achieve these ambitious goals, the colliders must deliver exceptionally high levels of luminosity, hence require high intensity hadron beam in the ring, which leads to high beam-beam parameter, as well as comparable space charge effects.
This study focuses on nonlinear effects that impact the beam dynamics within the hadron accelerator ring, including weak-strong beam-beam interactions and their interplay with space charge effects. Accurately predicting these non-linearities, particularly resonances arising during multi-turn acceleration, is critical for long beam lifetime and optimal
accelerator performance. This work presents an initial attempt to develop an optimized approach that integrates space charge effects across the entire ring length while incorporating localized beam-beam interactions at specific interaction points.

Speaker: Helena Alamprese (Michigan State University)

15:00 Rapidly pulsed synchrotron acceleration chain for a Fermilab sited muon collider

We present preliminary lattices for a rapid cycling synchrotron (RCS) chain based on a bottom up design for a 10 TeV parton center-of-momentum (pCM) muon collider sited at Fermilab. The smallest RCS rings in this lattice are 6.28 km in circumference and the largest RCS ring fitting fully within the Fermilab site is 15.5 km. To reach 5 TeV per beam, a single tunnel containing up to two rings is allowed to exceed the 15.5 km limit. Each ring is either a conventional RCS or a hybrid RCS. A conventional RCS relies on only iron dominated, ramped field magnets while a hybrid RCS relies on a combination of interleaved ramped field and superconducting fixed field magnets to achieve higher average magnetic fields while maintaining the high ramp rates achievable with iron dominated magnets. A pair of 6.28 km RCS rings and a 15.5 km RCS ring accelerate beams from 63 GeV to 1.54 TeV. Three scenarios for acceleration from 1.54 TeV to 5 TeV using an off-site tunnel are presented.

Speaker: Kyle Capobianco-Hogan (Stony Brook University)

15:00 Recent Progresses Regarding Enclosed RF Cavities for Future Muon Collider Cooling Channel

The muon collider (MuC) holds strong potential for reaching the 10 TeV energy frontier but introduces several technical challenges. Ionization cooling is essential to reduce beam emittance and achieve required luminosities. As muons lose energy in absorbers, normal-conducting RF cavities restore it. However, strong magnetic fields—needed for beam focusing—increase the risk of RF cavity breakdowns. Thin beam windows are used to reduce breakdown probability and improve shunt impedance. In this paper, we present some recent studies on these cavities, including: 1) evaluating emittance growth due to particle scattering in the beam windows made of Be and Al by GEANT4, 2) calculating the beam loading effect in the presence of the beam windows with CST wakeifeld solver and Particle-In-Cell solver, 3) deriving the breakdown thresholds for different cavity materials in strong B fields based on a thermal-mechanical model.

Speaker: Dillon Merenich (Northern Illinois University)

15:00 RF breakdown and dark current studies in short-pulse acceleration

Recent experimental studies at the Argonne Wakefield Accelerator (AWA) have shown that operating RF cavities with short pulses, only a few nanoseconds in duration, can raise the accelerating gradient to nearly 400 MV/m in a series of X-band structure tests. These results motivate further investigation into the breakdown physics underlying the short-pulse acceleration regime.
In this work, we present analytical models and numerical simulations of dark current dynamics in X-band cavities driven by short RF pulses. These studies explore key phenomena associated with RF breakdown across various time scales, including field emission, secondary electron emission, and plasma formation, with particular focus on their dependence on RF pulse length.
Building on these insights, we describe the design and experimental plan for a single-cell X-band RF cavity operating at 11.7 GHz, optimized for high-gradient operation with 6~ns long RF pulses and integrated with RF breakdown diagnostics.
This work aims to deepen the understanding of RF breakdown physics in the short-pulse regime and support the development of compact linear accelerators for future applications.

Speaker: Gaurab Rijal (Northern Illinois University)

15:00 Simulations of CSR and LSC induced microbunching in the presence of a laser heater

We present a study of microbunching amplification in linear accelerators, focusing on the combined effects of coherent synchrotron radiation (CSR) and longitudinal space charge (LSC). We also investigate the role of a laser heater, which is designed to suppress microbunching by decreasing the relative correlated energy spread early in the beamline. Simulations are performed for the FACET linac (SLAC), enabling direct comparison with existing theoretical predictions for CSR-induced microbunching in the presence of a laser heater. In addition to this comparison, we analyze microbunching amplification due to CSR and LSC both individually and jointly, highlighting their interplay. This work lays the foundation for upcoming experimental studies at FACET aimed at validating both theoretical models and numerical simulations.

Speaker: Sergei Kladov (University of Chicago)

15:00 Simulations of IBS through electric field fluctuations

We present a study of intra-beam scattering (IBS) that is important for high-brightness electron beams, including a recent theory incorporating enhanced temporal correlations of electric field fluctuations. These correlations primarily arise from the periodic betatron motion of particles within the beam that is not accounted for in conventional theories. To enable direct verification of the theoretical calculations, we perform simulations with particle distributions preserved over time, ensuring conditions compatible with theoretical assumptions.
We focus our study on the energy spread increase in high-brightness electron injectors. Energy spread growth is extracted from simulations in two ways: through the theoretical connection with field correlations, and directly from accumulated energy changes of individual particles. Comparisons are performed across multiple beam distributions and dynamics, from linear motion in an infinite uniform plasma to betatron oscillations in a Gaussian bunch.

Speaker: Sergei Kladov (University of Chicago)

15:00 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 progress towards characterization of the pulses in the time domain using hard x-ray angular streaking and a hard x-ray split and delay device.

Speaker: River Robles (Stanford University)

15:00 Single-shot longitudinal phase-space measurement of thermionic gun beam at the Advanced Photon Source linac

Advancements in particle accelerator technology hinge on our ability to precisely measure and understand the behavior of high-brightness beams. Following the installation of the new photo-cathode gun (PCG) laser at the front-end of the Advanced Photon Source (APS) linac, commissioning studies are needed to understand and bring the new PCG beam up to operational standard. In the present work, we present initial measurements characterizing the longitudinal phase-space of the thermionic-cathode gun (TCG) electron beam using a transverse deflecting cavity (TCav) located at the end of the APS linac. Downstream of the TCav, which deflects the beam vertically, lies the B1 horizontal bending magnet and three Chromium Oxide screens placed at three different locations where the beam is intercepted and imaged. Measurements of the TCG beam longitudinal phase-space are discussed and compared to previous measurements of the PCG beam longitudinal phase-space.

Speaker: Timothy Suzuki (Michigan State University, Argonne National Laboratory)

15:00 Sputter coating of Nb₃Sn into SRF cavity using stoichiometric target

Nb₃Sn has emerged as a leading alternative material due to its higher superconducting critical temperature (Tc) and superheating field (Hsh), promising a viable solution to the intrinsic performance limit currently faced by Nb superconducting radiofrequency (SRF) cavities. We sputter-coated Nb₃Sn inside Nb SRF cavity using a stoichiometric Nb₃Sn tube target in a DC cylindrical magnetron sputter coater. The target was fabricated by growing an estimated >20 μm thick Nb₃Sn layer on a Nb tube via Sn vapor diffusion using Jefferson Lab’s coating system. Approximately 150 nm thick Nb-Sn films were sputter-deposited onto flat Nb samples at positions representing the beam tubes and equator of a 2.6 GHz Nb cavity. Post-deposition annealing at 950 °C for 3 h resulted in the formation of Nb₃Sn. Microstructural analysis of the annealed films was carried out to investigate the morphology and structure of the Nb₃Sn films. Later, a 2.6  GHz Nb SRF cavity was coated with a ~1.2 μm thick sputtered Nb-Sn film using a stoichiometric Nb₃Sn target, followed by annealing. Cryogenic RF testing of the annealed cavity demonstrated a Tc of 17.8 K, indicating the formation of Nb₃Sn. After a light Sn recoating treatment, the cavity achieved a quality factor (Q0) of 6.7E+08 at lower field at 2.0 K.

Speaker: Md Sharifuzzaman Shakel (Old Dominion University)

15:00 Start-to-end simulations of nanometer-emittance beam transport through an emittance exchange beamline

We present start-to-end simulation study of the transport of a few pico-Coulomb, nanometer-emittance beam through an emittance exchange (EEX) beamline. EEX with nanometer-emittance beams has potential to enable research opportunities utilizing tunable and high quality attosecond bunches and nanometer-scale longitudinal bunch trains. To account future possibility of experimental demonstrations, the simulation implemented existing EEX beamline at Argonne Wakefield Accelerator (AWA) facility. Simulation was conducted using General Particle Tracer (GPT) code.

Speaker: Buse Naz Temizel Ozdemir (Northern Illinois University)

15:00 Study of uncorrelated resonance crossing in a controlled environment

This paper deals with estimating spin depolarization in planned very high energy electron-positron storage rings like the FCC-ee. The paper covers three aspects of the work: 1) the putative so-called uncorrelated resonance crossing due to noise in the spin-rotation phase advance caused by photon emission in synchrotron radiation. This is expected to suppress the depolarization caused by synchrotron sideband resonances, 2) a study of the performance of our code on multiple high performance systems, and 3) the novel exploitation of a high order Magnus expansion applied to spin transport. The study uses Monte-Carlo spin-orbit tracking for a simple model of spin motion, the so-called single resonance model, augmented by the effects of radiation. The results presented here represent the first steps of a planned detailed large-scale exploration.

Speaker: Jack Kelley (Virginia Tech, Los Alamos National Laboratory)

15:00 Surrogate Model for Third-integer Resonance Extraction at the Fermilab Delivery Ring

We present an ongoing work in which a surrogate model is being developed to reproduce the response dynamics of the third-integer resonant extraction process in the Delivery Ring (DR) at Fermilab. This is in pursuit of smoothly extracting circulating beam to the Mu2e Experiment’s production target, whereby the goal is to extract a uniform slice of the circulating 1e12 protons in the DR over 25,000 turns (43 ms). The DR contains 3 harmonic sextupoles that excite a third-integer resonance and three fast, tune-ramping quadrupole magnets that drive the horizontal tune towards the 29/3 resonance. In our initial work, the surrogate model trains on a semi-analytical simulation provided in the same format as live data. Using Reinforcement Learning (and other potential ML methods), the trained surrogate acts as the “environment” in which a simple ML control agent could learn to dynamically adjust the quadrupole ramp at 430 break points within the 43 microsecond spill window. The controller will be hosted on a dedicated Arria 10 FPGA. In this work, we report the accuracy and fidelity of the surrogate model in comparison to the response dynamics of the physics simulator.

Speaker: Aakaash Narayanan (Fermi National Accelerator Laboratory)

15:00 The implementation of adaptive step size Runge Kutta integrator in Zgoubi

The Zgoubi simulation code for beam and spin dynamics employs a numerical method based on Taylor series to integrate the Lorentz and Thomas-BMT equations, optimizing computational efficiency while ensuring high accuracy and robust preservation of motion invariants. In this work, we developed and implemented an adaptive step-size Runge-Kutta (RK) integrator into Zgoubi to tackle growing computational demands in accelerator physics simulations. This new integrator complements Zgoubi's default solver, offering users the flexibility to choose between integration methods based on specific simulation requirements. We demonstrated that the adaptive step-size RK integrator achieves the necessary accuracy and performance for integrating the Lorentz and Thomas-BMT equations effectively.
A key advantage of Zgoubi lies in its wide optical elements library, featuring over 60 accelerator components and variants, which the new adaptive step-size RK integrator can seamlessly utilize. Developed and rigorously tested over decades across numerous projects, this library provides a high degree of confidence in the code’s reliability. The same advantage holds about ancillary computations such as synchrotron radiation, space charge, decay in flight, etc. The implementation of the adaptive step-size RK integrator supports Zgoubi’s adaptability, enabling simulations of complex beam and spin dynamics with a trusted and well-established computational framework.

Speaker: Bhawin Dhital (Brookhaven National Laboratory)

15:00 The Pulsed Ion Reflex Klystron: A New Accelerator for High Efficiency Voltage Conversion

Beam Alpha developed a kilowatt-scale fusion microreactor that directly converts nuclear energy to electrical energy without intermediate heat steps. This device has an output of 1.6 million volts DC. A converter is needed to transform this potential energy into useful electrical power. To achieve this the "Pulsed Ion Reflex Klystron" has been developed. The PIRK aims to achieve high conversion efficiencies by directing negatively charged ions through a re-entrant resonant cavity hundreds of times to gradually transfer energy from the moving particles to said cavity. Ions will be released into a 6-meter linear accelerator with roughly 1000 precisely spaced electrodes forming a quasi-parabolic potential. This potential is symmetric about the midpoint of the tube causing ions to oscillate with a frequency of approximately 1 MHz independent of energy. Perturbations to this parabolic potential are designed to provide radial electrostatic beam focusing. An algorithm is devised to produce optimal voltage curves to maximize both longitudinal bunching and radial confinement, and these curves are examined against practically realizable potentials. Energy is coupled out of the resonant cavity using a loop antenna connected to a silicon carbide rectifying diode. This converts the RF in the cavity to a 400V intermediate DC bus that can easily be inverted to wall power.

Speaker: David Mengel (Beam Alpha Incorporated)

15:00 Third Integer Resonant Extraction Transit Time Simulation Studies

In this work, we present the investigation of transit time of particles in the non-linear third-integer resonant extraction process. Transit time is defined as the number of turns a particle takes to get extracted once it is in the unstable region in the phase space, i.e., outside the triangular separatrix in case of third-integer resonance. The study of transit time is important because transit time directly contributes to the beam response time during resonant extraction and thus knowing it apriori would be practically useful in designing of the extraction system. In this work, we shall investigate the analytical derivation of the transit time of particles (to the first order Kobayashi Hamiltonian) in different parts of the phase space distribution and compare against the analytical results. We also compare the simulation result of the transit time of particles (with higher statistics) for the static as well as dynamic extraction conditions cases, particularly in the context of resonant extraction parameters for Mu2e experiment at Fermilab.

Speaker: Aakaash Narayanan (Fermi National Accelerator Laboratory)

15:00 THz Detection and Investigation of Vacuum-Compatible Optical Components

Detecting terahertz (THz) radiation in ultra-high vacuum (UHV) environments presents notable challenges due to the limited availability of commercially compatible components. In preparation for upcoming THz measurements at the Argonne Wakefield Accelerator (AWA) facility, we investigated two critical aspects: (1) the THz transmission characteristics of fused silica windows, and (2) the suitability of commercial off-axis parabolic mirrors (OAPs) for use in UHV conditions. While fused silica is widely used in optical systems, its performance in the THz regime is rarely documented. We present transmission measurements and assess its viability for THz diagnostics. Additionally, we address the incompatibility of anodized, off-the-shelf OAPs with UHV by developing and testing both mechanical and chemical de-anodization techniques. These methods aim to maintain surface integrity and optical quality. This work provides practical guidelines and compatibility benchmarks for implementing THz diagnostics in UHV environments and serves as a reference for future experiments at AWA and other accelerator facilities.

Speaker: Calcifer Phillips (Northern Illinois University)

15:00 Towards Real-Time Calibration of CBPMs Using Synchronous RF Injection

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)

15:00 Transverse beam dynamics studies in the FRIB accelerating cryomodules

The accelerating segments in the Facility for Rare Isotope Beams (FRIB) linac contain superconducting RF cavities accelerating the beam and superconducting solenoids providing transverse focusing. We have studied the transverse emittance growth in the post-stripper linear accelerating segment of the FRIB linac. To understand the cause of the emittance growth we employ a macroparticle tracking code to simulate 3D beam dynamics in this segment of the linac. The model is being developed and validated by beam measurements. The measurements are focused on the response of the transverse beam position along the segment after the beam is kicked by dipole steering magnets at the entrance to this segment. The results of the studies with various beam species and energies will be presented.

Speaker: Alec Gonzalez (Facility for Rare Isotope Beams)

15:00 Tunable Terawatt Attosecond Soft‑X‑Ray Pulse Pair from a Plasma Wakefield Driven Free Electron Laser

Attosecond X-ray pulses are a pioneering tools for real-time observation of ultrafast electronic dynamics in atoms and molecules, opening up revolutionary advances in chemistry, materials science, and condensed-matter physics. Existing attosecond sources are, however, constrained by low photon energy and flux, which limits their experimental applications. we present here start-to-end simulations of soft-X-ray FEL, taking advantage of attosecond electron beam generated from PWFA to provide terawatt-level peak power in pulses of merely tens of attoseconds duration. High-brightness electrons produced in PWFA are longitudinally compressed in a magnetic arc and then injected into an undulator. By tuning the undulator taper, two isolated spikes of radiation—each tens of attosecond duration and terawatt peak power are generated for inherent pump–probe application with tunable delays. Such an ultraintense, ultrashort source offers a direct route to table-top X-ray light sources and facilitates attosecond-resolution experiments with unprecedented intensity and time resolution.

Speaker: Xuan Zhang (Stony Brook University)

15:00 Ultrafast Switching Utilizing an IVA Topology for Chopper Applications

Recent trends in power electronics indicate increas-ing demand for fast response switching networks with sub nanosecond switching speed at a variety of volt-ages. Gate driving networks meet the desired switch-ing speeds using COTS (Commercial Off-The Shelf) parts. This work describes an IVA (Inductive Voltage Adder) system capable of switching in the single digits of ns with a projected voltage output of 2 kV, using a gate driving topology to drive GaN (Gallium Nitride) HEMTs (High Electron Mobility Transistor). These rapid switching systems are proposed to be used in the LAMP (LANSCE Accelerator Modernization Project) chopper to effectively produce clean beam to select target stations, producing the needed output.

Speaker: Kyle Hansz (Los Alamos National Laboratory)

15:00 Unlocking SRF Performance: How Nitrogen and Oxygen Shape Cavity Performance

Nitrogen and oxygen-based surface treatments have revolutionized the performance of superconducting radiofrequency (SRF) cavities, enabling them to reach higher gradients and lower losses. However, the exact mechanisms by which these treatments improve cavity performance remain largely unknown. This work provides new insights into the role of nitrogen and oxygen in SRF cavity performance by using time-of-flight secondary ion mass spectrometry (TOF-SIMS) to precisely quantify the concentrations and depth profiles of these impurities within niobium cutouts. We correlate these impurity profiles with detailed cavity performance measurements, including surface resistance and quality factor, and compare our findings with predictions from BCS theory. The results demonstrate that while both nitrogen and oxygen enhance performance, ten times more oxygen is required to achieve the same reduction in BCS resistance as interstitial nitrogen. We present a potential model in which the observed variation arises from nitrogen's greater effectiveness in trapping hydrogen, thus reducing the formation of niobium hydrides and enhancing superconducting gap.

Speaker: Hannah Hu (University of Chicago)

15:00 Visualization Tools for EGUN Simulations

DC electron guns are essential sources of moderate-energy electron beams for both particle accelerators and klystrons. EGUN is one of the simulation software that is employed to design such DC guns. EGUN produces detailed data of electron rays trajectories for a given gun geometry, cathode temperature, bias-voltage, and beam current - whether space-charge limited or not. We use Mathematica and Python for advanced mathematical processing and visualization of the EGUN data visualization. For example, we generate phase-space plots at various longitudinal cross-sections and show the evolution of phase-space parameters along the beam axis. The visualization we generate is much richer than the simple trajectory plots generated by EPLOT software that accompanies EGUN. In this research work, we show the example of a practical Klystron gun and the results of our post-processing software.

Speaker: Katie Casey (University of Southern California, SLAC National Accelerator Laboratory)

18:30 → 20:30 Welcome Reception

Monday 11 August

08:00 → 08:45 Coffee

08:45 → 09:00 Opening

08:45 NAPAC 2025 Opening

Speaker: Tor Raubenheimer (SLAC National Accelerator Laboratory)

09:00 → 10:30 Monday Plenary

09:00 Electron-Ion Collider

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)

09:30 APS upgrade: Commissioning the world’s first light source based on swap-out injection

The Advanced Photon Source (APS) has recently completed a major upgrade, replacing its 25-year-old storage ring with a cutting-edge hybrid seven-bend achromat lattice enhanced by six additional reverse bends. The new design achieves a natural emittance of 42 pm-rad, enabling the production of X-rays up to 500 times brighter than those generated by the original APS. A key innovation of the upgrade is the implementation of a swap-out injection scheme, which replaces entire depleted bunches instead of performing traditional top-up injection. This approach enables on-axis injection to accommodate for the reduced dynamic aperture resulting from strong focusing. This paper outlines the commissioning process, shares initial operating experience with swap-out injection, and presents performance data for new systems such as the bunch-lengthening cavity.

Speaker: Vadim Sajaev (Argonne National Laboratory)

10:00 High Power Attosecond X-ray Pulses at LCLS-II

The LCLS-II upgrade has expanded the capabilities of the Linac Coherent Light Source (LCLS), extending the deliverable photon energy range and increasing the repetition rate from 120 Hz to a maximum of 1 MHz. Here we report the development of attosecond X-ray science capabilities at the LCLS-II, including the commissioning of beam shaping methods for attosecond pulse generation, and the demonstration, characterization, and delivery of advanced attosecond XFEL modes at high repetition rates. We used the photocathode modulation method$*$ at LCLS-II to generate single-spike pulses with up to 10s uJ pulse energy. These attosecond pulses are characterized at the TMO instrument with the angular streaking technique$**$. Furthermore, we demonstrated advanced modes such as spectrotemporally shaped attosecond pulses$***$ and pump/probe attosecond pulse pairs. These capabilities have been delivered at a repetition rate of up to 33 kHz, enabling the next generation of ultrafast experiments at XFELs.

Speaker: Paris Franz (Stanford University)

10:30 → 11:00 Coffee

11:00 → 12:30 Colliders and other Particle and Nuclear Physics Accelerators (Invited)

11:00 The future circular collider in Europe

The proposed Future Circular Collider (FCC) integrated programme consists of two stages: An electron–positron collider serving as a highest-luminosity Higgs-boson, electroweak and top-quark factory, followed by a proton–proton collider with a collision energy around 100 TeV. In 2021, 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 Feasibility Study was completed on 31 March 2025. The subsequent European Strategy Symposium has singled out the FCC as the by-far preferred future collider option for CERN. I will present a few study highlights, the status, and the next steps.

Speaker: Frank Zimmermann (European Organization for Nuclear Research)

11:30 Recent experience with high-luminosity operation of SuperKEKB

SuperKEKB is a positron-electron collider with a nano-beam scheme. The nano-beam scheme allows the extremely low beta function at the interaction point (IP) compared to the bunch length, namely ordinary colliders. The beta function at the IP is less than 1 mm which is the smallest value among the previous colliders. Recent results on beam-beam interactions, beam injection under the influence of beam-beam interactions, and a performance of the crab-waist scheme that improves the luminosity performance are discussed. Sudden beam loss (SBL), which cannot be explained by usual beam dynamics, and the nonlinear collimator as a key device to reduce both beam background and impedance are also crucial issues. We present the recent machine operation and performance of SuperKEKB which predicts the future high energy and luminosity colliders.

Speaker: Yukiyoshi Ohnishi (High Energy Accelerator Research Organization)

12:00 Recent Developments for a High-Energy Linear Collider

As part of the European Strategy in Particle Physics Update (ESPPU) the particle physics community is evaluating the options for the next flagship project at CERN. Immense interest in exploring the physics of the Higgs sector and the potential for discovering new physics at high energy is at the core of our motivation for pursuing the next particle collider. The Linear Collider Vision collaboration is exploring how this physics can be pursued with a linear collider facility (LCF) at CERN. A LCF with polarized electron and positron beams, reaching energies of up to about 1 tera electron volt (TeV), would offer a rich program to explore the Higgs boson, the top quark and perform search for new physics in a way that is highly complementary to HL-LHC. Technology upgrades could push this energy reach even higher. In this talk we will present recent developments in linear colliders and technical challenges of implementing a linear collider at CERN. An overview of the Linear Collider Vision and LCF @ CERN inputs to the ESPPU will be presented.

Speaker: Emilio Nanni (SLAC National Accelerator Laboratory)

11:00 → 12:30 Photon Sources and Electron Accelerators (Invited)

11:00 Operation of the APS-U injectors with high single bunch charge

The APS-Upgrade uses swap-out injection, which means the injectors must supply a full charge bunch (up to 16 nC) to replace a depleted one in the storage ring.  The APS injector chain consists of a linac, particle accumulator ring (PAR), and booster synchrotron. These machines were kept in place for the APS-U, with several key upgrades to support high charge operation.  Major upgrades include a new timing system, improved diagnostics, and a new amplifier for bunch compression in the PAR. So far, the injectors have supported up to 140 mA storage ring current in the high charge (48 bunch) mode. This talk will summarize the work needed to achieve high injector charge, and report on operational experience so far.

Speaker: Joseph Calvey (Argonne National Laboratory)

11:30 Advances in beam physics and technology for ultrafast electron diffraction

Ultrafast electron diffraction (UED) is a rapidly advancing field, with a surge of scientific outcomes and significant progress in the development of high-brightness electron beams tailored for improved resolution and signal-to-noise ratios. In this talk, we will present recent developments in beam physics and technology aimed at producing beams with lower emittance, shorter bunch lengths, tighter timing synchronization, and better stability for UED, as well as for broader applications that demand high-brightness, precisely controlled beams.

Speaker: Renkai Li (Tsinghua University)

12:00 Commissioning of the HEPS

The High Energy Photon Source (HEPS) is the first 4th generation light source and the first high-energy storage ring light source in China, with a beam energy of 6 GeV, a circumference of 1360 m and a natural emittance of a few tens of picometers. As a green-field light source, the HEPS construction started in 2019 and is scheduled to be completed in 2025. Now civil construction, component fabrication and tunnel installation, and beam commissioning of the HEPS has been basically finished. In this report, the accelerator and especially the storage ring commissioning results, and main physics issues faced and corresponding measures during the beam commissioning will be presented.

Speaker: Ping He (Institute of High Energy Physics)

12:30 → 14:00 Lunch

14:00 → 15:30 Hadron Accelerators (Invited)

14:00 The Fermilab Accelerator Complex in the multi-MW era

The Fermilab Accelerator Complex is currently home to the world's most powerful neutrino beam, driven by a 1 MW 120 GeV proton beam. The forthcoming PIPII upgrade will further enhance this capability, although additional enhancements are necessary to meet the integrated beam requirements of the DUNE project. The past performance will be summarized and the Accelerator Complex Evolution (ACE) plan will be outlined, which involves various strategies for achieving multi-MW beams. In particular, the ACE-MIRT component, which involves upgrading the Main Injector and targetry will be discussed in detail.

Speaker: Robert Ainsworth (Fermi National Accelerator Laboratory)

14:30 Beam Based Alignment in the CeC Experiment

During the coherent electron cooling (CeC) experiment at RHIC, we have encountered various challenges to align the electron beam both in the low energy beam transfer line (LEBT) and in the cooling section. For example, the electrons exit the SRF gun with an orbital angle of tens of milli-radian, which is likely caused by the misalignment of the cavity inside the cryostat as well as the tilted cathode. The significant orbital angle leads to transversely asymmetric beam in the LEBT section with deteriorated emittance. In run 23 and run 24, we have demonstrated that such orbital angle at the exit of the gun can be minimized by adjusting the position of the laser spot at the cathode. Another challenge is to align the orbit of the cooling electron beam with the circulating ion beam in the cooling section. Over the past few years, we have developed a procedure to ensure the transverse alignment to the precision of 0.1mm. The proper alignment of the two beams has been confirmed by significant growth of the ion beam’s longitudinal emittance due to its interaction with the electron beam as well as increased signal from the recombination monitor. In this paper, we will present the techniques developed for beam alignment with experimental results obtained in the CeC experiment.

Speaker: Gang Wang (Brookhaven National Laboratory)

15:00 A test stand for LAMP, the LANSCE accelerator modernization project

The Los Alamos Neutron Science Center (LANSCE) has been in service for over 50 years. The LANSCE accelerator is exhibiting an increasing rate of end-of-life issues, particularly in the “front end” region – from the ion sources to the end of the 100-MeV drift tube linac (DTL). The LANSCE Accelerator Modernization Project (LAMP), recently been approved for CD-0, will replace the existing LANSCE front end with new ion sources followed by an RFQ and new DTL, with co-acceleration of H- and H+ through the RFQ and DTL. This talk outlines the scope of the LAMP project with a focus on the efforts of building and commissioning the RFQ Test Stand which will demonstrate simultaneous dual beam species through an RFQ.

Speaker: Remington Thornton (Los Alamos National Laboratory)

14:00 → 15:30 Novel Particle Sources, Acceleration Techniques, and their Applications (Invited)

14:00 Exploration of ultra-high dose rate radiobiology with laser-driven protons at BELLA

Laser-driven (LD) proton sources are of interest for various applications due to their ability to produce short proton bunches with high charge and low emittance. These sources can be used in biological studies investigating improvements to radiation cancer therapy. Recently, the differential sparing effect on normal tissues versus tumors using the delivery of high radiation doses >10 Gy at extremely high dose rates (DR), called FLASH effect, has received increasing attention. However, the molecular and cellular mechanisms underlying the sparing effect are not yet fully understood. To explore these mechanisms, we have implemented a beamline at the BELLA PW that delivers LD proton bunches at ultra-high instantaneous DR (UHIDR) up to $10^8$ Gy/s. This allowed us to investigate in vivo the acute skin damage and late radiation-induced fibrosis in mouse ears after UHIDR with 10 MeV LD protons and prescribed doses of several 10 Gy. We observe sparing of healthy mouse ear tissue after irradiations with LD proton bunches at UHIDR compared to irradiations with 300 kV x-rays at clinical dose rates and similar total dose. Recent improvements to the LD proton source, delivery beamline, and diagnostic suite have also enabled first peptide sample irradiations to explore the sparing effect on the molecular level. This talk will provide a summary of radiobiology research activities at the BELLA PW.

Speaker: Lieselotte Obst-Huebl (Lawrence Berkeley National Laboratory)

14:30 Bright bunch generation in a short pulse high gradient RF gun operating in the transient regime

Normal-conducting accelerating structures capable of supporting GV/m-scale electric fields offer a promising pathway to compact accelerators. Similarly, achieving such high fields in photocathode guns is critical for the generation of bright electron bunches. Our group has demonstrated the generation of ~0.4 GV/m electric fields on a photocathode surface in an X-band (11.7 GHz) photoemission gun (Xgun) powered by short RF pulses (~9 ns). In this work, we investigate the RF characteristics and beam dynamics evolution in the transient field regime. Accurately accounting for the transient nature of the RF field is essential for optimizing the beam dynamics and ensuring the production of high-quality electron bunches.

Speaker: Gongxiaohui Chen (Argonne National Laboratory)

15:00 Testing Photocathodes in Extreme Conditions

Photocathodes are the electron sources of choice for accelerator applications that rely on bright and ultrashort electron bunches, including next-generation light sources and electron microscopes. These applications benefit significantly from photocathodes with low mean transverse energy (MTE), which directly contributes to higher beam brightness and better transverse coherence. However, the need for high charge densities, combined with the disordered structure of many photocathode materials, surface roughness, and spatial work function variations, limits the achievable MTE from conventional photocathodes to several hundred meV, which is nearly two orders of magnitude above the theoretical minimum. Additionally, most commonly used photocathodes degrade under high electric fields or intense laser fluences, posing challenges for reliable operation in advanced accelerator environments. Robust photocathodes capable of sustaining these extreme conditions while delivering bright electron beams with significantly reduced MTE are thus critical for enabling next-generation accelerator performance. In this talk, we will highlight recent advances in photocathode development and testing under extreme conditions, including high fields and cryogenic temperatures, conducted by the Center for Bright Beams (CBB, https://cbb.cornell.edu) and beyond toward brighter, more resilient electron sources.

Speaker: Oksana Chubenko (Northern Illinois University)

15:30 → 16:00 Coffee

16:00 → 18:00 Monday Poster Session

16:00 A new Python middle layer framework: Particle Accelerator MIddle LAyer (PAMILA)

MATLAB Middle Layer (MML) for accelerator control has been used by many facilities worldwide over the years. With the rise of Python's popularity, particularly for leveraging its advanced artificial intelligence and machine learning libraries, an international collaboration is underway to develop a similar software framework in Python. As part of this effort, we propose a new Python middle layer package, which is built on top of the pint unit-conversion package, and capable of handling any type of device-dependent unit conversion (including multiple-input multiple-output) for magnets and other equipment. This package is also compatible with a suite of modern experimental orchestration and data management tools widely used by beamlines at many light sources (i.e., bluesky, ophyd, and tiled), and provides a more modular approach for implementing high-level applications, facilitating re-use, while exposing comprehensive, yet manageable, options to end users.

Speaker: Yoshiteru Hidaka (Brookhaven National Laboratory, National Synchrotron Light Source II)

16:00 A reactive ferroelectric tuner for microphonics compensation

Jefferson Lab (JLab) is actively pursuing an extensive research program focused on developing advanced Nb₃Sn superconducting technology for particle accel-eration. Due to the brittle nature of Nb₃Sn coatings, a Ferroelectric Tuner (FRT) currently represents the most viable approach for microphonics compensation in these next-generation cavities. We suggest a novel, fast-responding FRT integrated directly into the main coupler, eliminating the need for an additional RF port. Leveraging a unique RF design based on a magic-T configuration, this advanced FRT will enable micro-phonics compensation in the ±30 Hz range without undesirable changes to the external quality factor.

Speaker: Dr Sergey Kuzikov (Thomas Jefferson National Accelerator Facility)

16:00 A self-supervised transformer for RF cavity signal denoising

A frequent occurrence within industrial particle accelerator systems is electromagnetic noise accumulating within RF Cavity Sensor readings, attributed to their electromagnetically dirtier operating environments and production, with less of an emphasis on their performance optimization. This phenomenon prevents signals from accurately relaying information to beam operators and specialists. Additionally, noisy signals inhibit the ability for feedback loops to meet their regulation requirements, making machine control much more difficult. Previous work has shown machine learning-based techniques as promising solutions for denoising that maintains signal quality and features. In this paper, we design, implement, and benchmark a self-supervised transformer-based machine learning algorithm that denoises In-Phase and Quadrature (I/Q) RF Cavity Signals without a need for referencing a clean ground-truth.

Speaker: Vikshar Rajesh (RadiaSoft (United States))

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

Performance drift over long periods of operation due to changes in machines settings or the environment has been a longstanding problem for particle accelerators. Algorithms which are capable of tuning machine settings while keeping the performance within a desired threshold can be used to compensate for such drifts. We have developed a modified version of the Multi-Generation Gaussian Process Optimizer (MG-GPO) which is capable of tuning accelerator settings during user operation. The modified algorithm uses Gaussian Process regression to predict the performance of potential trial settings and removes ones with a high probability of giving too poor of a performance before selection for evaluation on the machine. The modified MG-GPO has been tested on analytic functions and applied to the SPEAR3 kicker-bump matching problem as a proof of concept. It is expected that the modified MG-GPO will be applied to maintain optimal trajectory of the beam injected into the SPEAR3 storage ring.

Speaker: Ryan Yeung (Michigan State University)

16:00 Advancing accelerator virtual beam diagnostics through Latent Evolution Modeling: An integrated solution to forward, inverse, tuning, and UQ problems

Virtual beam diagnostics relies on computationally intensive beam dynamics simulations where high-dimensional charged particle beams evolve through the accelerator. We propose Latent Evolution Model (LEM), a hybrid machine learning framework with an autoencoder that projects high-dimensional phase spaces into lower-dimensional representations, coupled with transformers to learn temporal dynamics in the latent space. This approach provides a common foundational framework addressing multiple interconnected challenges in beam diagnostics. For forward modeling, a Conditional Variational Autoencoder (CVAE) encodes 15 unique projections of the 6D phase space into a latent representation, while a transformer predicts downstream latent states from upstream inputs. For inverse problems, we address two distinct challenges: (a) predicting upstream phase spaces from downstream observations by utilizing the pretrained CVAE with transformers trained on reversed temporal sequences, and (b) estimating RF settings from the latent space of the trained LEM using a dedicated dense neural network that maps latent representations to RF parameters. For tuning problems, we leverage the trained LEM and RF estimator within a Bayesian optimization framework to determine optimal RF settings that minimize beam loss. This paper summarizes our recent efforts and demonstrates how this unified approach effectively addresses these traditionally separate challenges.

Speaker: Mahindra Rautela (Los Alamos National Laboratory)

16:00 AI-ready control infrastructure for cyclotron systems using GPU-accelerated Python GUIs and LabVIEW over ZeroMQ

We present a modular, AI-ready control and monitoring infrastructure developed for the 76-inch isochronous cyclotron at the Crocker Nuclear Laboratory, University of California, Davis. The system combines a GPU-accelerated Python GUI engine on a high-performance Linux workstation with a LabVIEW-based supervisory platform for real-time control and data acquisition.
Communication between platforms is handled via ZeroMQ, enabling low-latency, asynchronous data exchange. Benchmark results show end-to-end response times below 10 ms with minimal jitter, supporting real-time visualization and interactive feedback.
Designed to separate deterministic control from high-level logic and user interaction, this architecture offers robust performance, scalability, and extensibility. It lays the groundwork for future integration of AI-based optimization, autonomous control, and predictive diagnostics in cyclotron operations.

Speaker: Claudio Lopez Osses (University of California, Davis)

16:00 Analog signal multiplexing system for the IOTA Proton Injector

The Fermilab Accelerator Science and Technology (FAST) Facility at FNAL is a dedicated research and development center focused on advancing particle accelerator technologies for future applications worldwide. Currently, a key objective of FAST Operations is to commission the 2.5 MeV IOTA Proton Injector (IPI) and enable proton injection into the IOTA storage ring. The low and medium-energy sections of the IPI include four frame-style dipole trims and two multi-function correctors with independently controlled coils, requiring readout of 32 analog channels for current and voltage monitoring in total. To reduce cost and optimize rack space within the PLC-based control system, a 32-to-4 analog signal multiplexing system was designed and implemented. This system enables real-time readback of excitation parameters from all magnetic correctors. This paper presents the design, construction, implementation, and performance of the multiplexing system.

Speaker: Daniel MacLean (Fermi National Accelerator Laboratory)

16:00 Anomaly detection of slow-moving variables at LANSCE for improved beam quality

Modern accelerator facilities operate with a large number of variables, many of which can influence beam quality. While most of these variables are constrained within predefined boundary conditions, slow fluctuations over extended periods—from tens of minutes to a full day—can still significantly degrade beam performance. Due to their gradual nature and the difficulty in distinguishing meaningful trends from background noise, such variables often go unnoticed and remain unoptimized by operators for days.
This study investigates the use of machine learning algorithms to identify and analyze these slow-moving variables. By applying advanced time-series analysis and feature importance ranking, the proposed approach reveals hidden correlations between slow variable drifts and a key beam quality metric: the ring loss at the Los Alamos Neutron Science Center (LANSCE). The results demonstrate the potential of machine learning to detect subtle anomalies and offer actionable insights to mitigate persistent beam quality issues that can disrupt operations for weeks at a time.

Speaker: En-Chuan Huang (Los Alamos National Laboratory)

16:00 Application of Bayesian optimization to BtA injection at BNL

Drifting optimal settings and changing working conditions force accelerator operators to keep re-tuning control systems. At BNL, the RHIC injector complex accelerates many different ion species by varying a multitude of control knobs. In this report, we investigate the use of Bayesian optimization (BO) of the Booster-to-AGS (BtA) transfer line to maximize the beam brightness in the AGS. The most suitable magnets were chosen by an investigation of the betatron phase advance to facilitate an efficient BO process, using up to 4 steering magnets and up to 3 quadrupoles. To quantify the beam intensity, we used an integrated current transformer, while the beam emittance was estimated via an Ionization Profile Monitor (IPM). It was demonstrated that the chosen magnets effectively recovered a high intensity beam from a poorly tuned configuration, using an Xopt implementation of BO, without increasing the beam profile. A new electron-collecting IPM is being configured with better systematics and lower noise compared to the current ion-collecting IPM, which can further improve this process.

Speaker: Eiad Hamwi (Cornell University)

16:00 AtomicAndPhysicalConstants.jl – A fast Julia package to access particle properties and fundamental constants

To support constants lookup for the SciBmad project, we introduced AtomicAndPhysicalConstants.jl, a Julia package that provides physical constants, subatomic particle properties, and atomic isotope data. It aggregates datasets from NIST (CODATA) and the Particle Data Group, offering a unified interface. The package supports configurable unit systems and data types, and integrates with the Julia package Unitful.jl. The package emphasizes speed and ease of use, making it well-suited for high-performance simulations and physics-driven modeling.

16:00 Automated RF phase adjustment for beam stabilization in the Fermilab Linac

The Fermilab Linac delivers 400 MeV H- beam. Variations in environmental factors and Ion Source output result in day-to-day longitudinal phase drift leading to increased beam loss. Traditionally, phase drift is corrected by manual RF cavity phase adjustments, a process that is labor-intensive and suboptimal. This work explores machine learning-based automation of drift correction using data-driven modeling of the Linac behavior. After extensive experimentation with single-layer, multi-layer, and convolutional neural networks (CNN+NN), we now adopt a prototype-based classification approach to identify optimal correction strategies. The model leverages a reduced 34-dimensional feature set comprising 7 RF cavity settings and 27 Beam Position Monitor (BPM) phase readings. To model the beam longitudinal response, we construct a 7×27 response matrix by varying the 7 cavity phases. Due to the limited set real-world data, synthetic data generation from the response matrix is also being explored to enhance model training. This enables the simulation of diverse drift scenarios and improves the generalizability of learned corrections. Finally, in addition to the prototypical loss framework, we incorporate a surrogate energy-consistent loss that penalizes inconsistencies between predicted phase corrections and changes in beam energy—estimated from the 27 BPM readings—alongside a temporal smoothness constraint that discourages abrupt prediction shifts across sequential readings.

Speaker: Ralitsa Sharankova (Fermi National Accelerator Laboratory)

16:00 Automation of sample alignment for neutron beamlines

Neutron scattering experiments are crucial for the exploration of molecular structure in compounds. The HB-2A neutron powder diffractometer at the High Flux Isotope Reactor at Oak Ridge National Laboratory conducts magnetic studies of samples by illuminating them with different energy neutron beams and recording the scattered neutrons. Proper and consistent alignment of the sample is necessary to ensure that high quality data is collected throughout an experiment. This process is currently performed manually by beamline scientists. RadiaSoft, in collaboration with the beamline scientists and engineers at ORNL, has developed a reinforcement learning-based agent capable of aligning and isolating samples. We use a Q learning structure to train the agent. The agent identifies the method to move the sample to the center of the beam and the proper amount to close the neutron camera slits. We then move the sample and close the slits using a custom Python-based EPICS IOC interfaced with the sample and slit motors. In this paper, we provide an overview of our reinforcement learning tools and show our results aligning samples like those at ORNL.

Speaker: Amelia Chen (RadiaSoft (United States))

16:00 Automation of sample identification for neutron beamlines

Neutron scattering experiments are a critical tool for the investigation of molecular structure in compounds. The HB-2A neutron powder diffractometer at the High Flux Isotope Reactor at ORNL conducts magnetic studies of samples by illuminating them with different energy neutron beams and recording the scattered neutrons. Proper identification and alignment of samples during an experiment is key to ensuring high quality data is 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 software automating sample identification. We utilize a fully connected convolutional neural network configured in a U-Net architecture to identify the sample and its 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 identifying samples at ORNL.

Speaker: Amelia Chen (RadiaSoft (United States))

16:00 Bayesian Calibration of the AWA Photocathode Gun Using YAG Screen Diagnostics and OPAL Simulations

We present a data-driven characterisation of the photocathode gun at the Argonne Wakefield Accelerator (AWA) using Bayesian inference, combined with OPAL beam dynamics simulations. Our methodology employs readily available YAG screen diagnostics to perform calibration across a range of experimental conditions, including varying cathode voltages, laser profiles, and beam currents. By integrating these diagnostics with forward beam dynamics simulations from OPAL, we estimate key gun parameters, such as the gun voltage and phase from beam current and solenoid currents. Ongoing work will further refine the calibration process and explore the integration of other diagnostics to enhance the inference process. This allows for more efficient and flexible calibration of complex accelerator systems, particularly with limited readily available measurements

Speaker: Sebastian Heinekamp (Paul Scherrer Institute)

16:00 Beam scattering through foil

This paper describes the foil structure used at the beam extraction point in the NASA Space Radiation Laboratory (NSRL) beamline. The stripping foil removes electrons from incoming ions, rendering them partially or fully stripped. Foils of various materials and thicknesses are employed, enabling ion species at different energies to pass through. As charged particles traverse a foil, the outgoing particles exhibit a Gaussian-like angular distribution. This distribution is subsequently transformed into a uniform profile by a set of octupole magnets, essential for various beam experiments at the NSRL target.
We utilize the Bmad and SRIM computer codes to calculate the energy loss through the foils for different ion species, energies, and charge states. After preparing ion beam species in the Booster, we determine the energy loss by measuring the horizontal beam profile at the multi-wire MW063 location in the NSRL beamline. Finally, we present a summary of energy loss calculations obtained through Bmad, SRIM, and experimental data.

Speaker: Bhawin Dhital (Brookhaven National Laboratory)

16:00 Benchmarking the use of BPM quadrupole moments to measure emittance

For the PIP-II program, transverse emittance in the Fermilab Booster must remain well controlled at higher bunch intensities. 4-plate beam position monitors (BPMs) have a small but measurable quadrupole moment, making it possible to infer transverse emittance. By compositing many BPMs together, it becomes possible to improve the quality of the quadrupole signal. The Fermilab Booster BPM system has been used to measure these quadrupole moments in the past year and derive emittances from them. Recent benchmarks show that the derived BPM emittances show similar emittance evolution and value to IPM and Multiwire data. This approach can both supplement and complement existing non-intercepting emittance monitors in accelerators.

Speaker: Michael Balcewicz (Fermi National Accelerator Laboratory)

16:00 Bunch duration measurements in the APS-U booster

We present the results of time-based, bunch length measurements in the Advanced Photon Source Upgrade booster synchrotron using the bunch duration monitor (BDM) optical diagnostic. The BDM diagnostic is based on the detection of visible-wavelength synchrotron radiation. The detector is a metal-semiconductor-metal device followed by 42 dB of wide-band amplifier gain. Bunch duration is determined by de-convolving the raw output signal with the circuit’s impulse response function. The BDM allows measurement of bunch duration over virtually the entire booster ramp. De-focusing in the optical path was necessary to overcome thermal steering from the in-tunnel mirror. Also, the effects of detector saturation must be considered to ensure a linear response. Presently, the booster increases bunch energy from 425 MeV to 6 GeV. Booster charge varies from 5 nC to 13 nC depending on storage ring operating modes. BDM data reveal that the bunch undergoes large longitudinal oscillations shortly after injection into the booster. The longitudinal oscillations are compared with elegant simulations. These oscillations are a source of injection loss especially at higher charge.

Speaker: Joseph Calvey (Argonne National Laboratory)

16:00 Calculating beam extinction in a pulsed proton beam 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”. Utilizing a new μTCA-based FPGA data acquisition system, we recorded live particle data from scattered particles incident on an array of quartz Cherenkov radiators and photomultiplier tubes to measure the extinction in the inter-pulse gaps in the pulsed proton beam. Minuscule errors in the derived signal period can make a measurement of the extinction impossible, so after taking a Fourier transform, further optimizations on the period were done based on the assumption that the signal period is stable over the full time of the beam spill while it is being resonantly extracted. After these optimizations, the beam extinction was shown to be on the level of $10^3$.

Speaker: Ryan Hensley (University of California, Davis)

16:00 Compact 3D electro-optic sampling beam position monitor

RadiaBeam and University of Colorado Boulder have developed a 3D beam position monitor based on the well-established electro-optic sampling (EOS) technique, enabling non-interceptive, ultrafast position monitoring of high-intensity femtosecond beams. Based on the initial prototype of the 2D EOS-BPM, using 1 pair of crystals, installed at SLAC FACET-II, this 3D design has undergone several iterations. A fully functional prototype was manufactured and bench tested using Off-Axis Parabolic (OAP) mirrors to focus the laser on 2 sets of 2 crystals. However, due to the difficulty of working with OAPs and the offset of the crystal pairs, a new EOS-BPM was developed using an axicon lens to shape the laser into an annulus at the crystal plane. This dramatically simplifies the setup, reduces its footprint, and provides full 3D information from a single laser beam. Once installed, the EOS-BPM can yield the full 3D centroid positioning of two bunches in a wakefield accelerator, or the tilt of a beam used to power a light source. Under ideal conditions, simulation-based estimates show temporal and transverse resolution for the beam centroids of a two-bunch wakefield accelerator beam of order 50 fs and 1 μm, respectively.

Speaker: Tara Hodgetts (RadiaBeam Technologies (United States))

16:00 Design of a BPM pick-up for the EIC electron storage ring

A new beam position monitor (BPM) pick-up, compatible to operate reliably with the high current electron beams foreseen in the 5 - 18 GeV Electron Storage Ring (ESR) of the Electron-Ion Collider (EIC) project, is presented. We discuss a few design options for this button-style BPM pick-up with a focus on output signal levels, position characteristic, and wakefield effects. Regarding the octagonal cross-section geometry of the ESR vacuum chamber, the BPM pick-up analysis relies on numerical methods, here performed using the CST Studio software.

Speaker: Medani Sangroula (Brookhaven National Laboratory)

16:00 Design of phase diversity Electro-Optic Sampling of THz coherent transition radiation

We report progress on the design of a Phase Diversity Electro-Optic Sampling (DEOS)-based longitudinal profile measurement system. The current design uses THz coherent transition radiation (CTR) to convey the bunch’s longitudinal information. A 1550nm fiber laser available at the Argonne Wakefield Accelerator facility will be used as the probe for electro-optic sampling. Specifically, we discuss pulse synchronization and probe beam transport, the design and optimization of the probe beam stretcher, and the design of the probe beam detection system.

Speaker: Spencer Kelham (Northern Illinois University)

16:00 Design, characterization, and validation of a pulsed RF burst source for in-situ cavity beam position monitor calibration

Beam Position Monitors are critical instruments in accelerator facilities, providing precise beam orbit measurements with tens of nanometers resolutions, essential for the operation of current linac-based FELs and future linear colliders. In this report, we introduce the development and successful testing of a pulsed RF burst source specifically designed for BPM calibration. The source was characterized and installed at the ATF2 facility in KEK, Japan. The system injects tailored RF pulses into the BPM cavity via one of the two output ports. With the capability to adjust frequency and pulse width, to emulate beam pulses, the system demonstrated nearly complete cancellation of beam-generated signals when the injected RF pulse overlapped with the beam pulse. This source has the potential for in-situ BPM calibration, mitigation of static signal contributions caused by cavity misalignments and capacity for wakefield compensation. Dedicated hardware development for further refinement of the source is underway at Royal Holloway, University of London, using two TI LMX2820 high-frequency synthesizers triggered by a shared external source to achieve precise phase synchronization between distinct frequencies at defined delays. Preliminary measurements indicate a phase jitter of about 1.2 degrees, currently limited by the trigger signal’s slow rising edge (tens of ns), while system requirements demand sub-nanosecond (hundreds of ps) precision for robust, high-frequency phase locking.

Speaker: Konstantin Kruchinin (SLAC National Accelerator Laboratory)

16:00 Detectors and beam monitors based on wide bandgap semiconductors at cryogenic temperatures

Wide-bandgap semiconductors, such as single-crystal diamond and sapphire, can be used to measure the flux of passing particles through a particle-induced conductivity effect. We recently demonstrated a diamond-based, electrodeless electron beam halo monitor. This monitor utilized a thin diamond blade placed within an open, high-quality microwave resonator. The blade partially intercepted the beam and changes in the RF properties of the resonator were used to infer beam parameters. To enhance the sensitivity of our semiconductor sensors, we propose two new techniques: (1) biasing the semiconductor sensor to support avalanche multiplication of free carriers, and (2) operating at cryogenic temperatures to reduce intrinsic semiconductor losses and increase the mobility of induced carriers. These techniques are applicable not only to particle beam diagnostics but also to the detection of various types of ionizing radiation.

Speaker: Dr Sergey Kuzikov (Thomas Jefferson National Accelerator Facility)

16:00 Development and applications of differentiable coherent optical transition radiation simulations

Optical transition radiation (OTR) beam profile monitors are widely used to measure the transverse profiles of low-charge electron bunches at advanced linear accelerator facilities such as LCLS-II and FACET-II. However, in scenarios involving strong longitudinal compression or microbunching-induced current spikes, the incoherent OTR signal—proportional to the transverse beam density—is often dominated by coherent OTR (COTR). The resulting COTR patterns exhibit complex dependencies on the full spatiotemporal structure of the beam, rendering conventional profile interpretation ineffective. In this work, we present a novel, backwards-differentiable simulation framework for COTR emission, enabling gradient-based inference of beam characteristics directly from COTR images. We further integrate this framework with the generative phase space reconstruction (GPSR) method to recover high-fidelity 4D transverse phase space distributions of strongly compressed beams. Simulation results demonstrate the ability of this approach to accurately reconstruct detailed beam structure from COTR-based diagnostics, offering a new path toward high-resolution characterization of ultrashort electron bunches.

Speaker: Ryan Roussel (SLAC National Accelerator Laboratory)

16:00 Development of an upgraded fast orbit feedback system for NSLS-IIU

As light source facilities evolve, upgrading fast orbit feedback systems is essential for improving beam stability. NSLS-II is planning an upgrade to NSLS-IIU, which introduces stricter stability requirements for advanced experiments. To address this, we developed a next-generation fast orbit feedback prototype system to enhance noise suppression and extend control bandwidth beyond 1 kHz. A system-wide evaluation was conducted, covering beam position monitors, cell controllers, power supply controllers, power supplies, and vacuum chamber effects. Latency and bandwidth bottlenecks were identified in the cell and power supply controllers. A new cell controller was designed to increase the sampling rate from 10 kHz to 31.5 kHz and reduce system latency to under 70 µs. The transfer function and gain measurements of a single-input-single-output system show a 10-dB improvement in noise suppression and an extension of bandwidth into the kHz range. We present the development and performance results of the upgraded system, offering a path toward higher beam stability at NSLS-IIU.

Speaker: Sukho Kongtawong (National Synchrotron Light Source II, Synchrotron Light Research Institute)

16:00 Development of diamond-based halo monitor diagnostics for an electron accelerator

High-resolution diagnostic instruments for measuring particle beam profile and charge are essential for characterizing the improved performance of charged particle accelerators. Beam diagnostics based on synthetic single crystal diamond (SCD) exhibit superior radiation-hardness, chemical stability, fast saturated drift speed, and unparalleled thermal conductivity. At Los Alamos National Laboratory (LANL), the SCD sensor and the high-speed signal acquisition system have been developed for measuring intensity of individual bunches. At the Argonne Wakefield Accelerator, a 63 MeV electron beam with diameter of 5 mm and charge below 10 pC used to measure the beam halo at a radial distance of 12 mm from the beam center. This presentation will report on the detailed SCD design and electronics, halo monitoring at various charges, bunches, and distances, and plans for future testing at LANL.

Speaker: Dongsung Kim (Los Alamos National Laboratory)

16:00 Digital camera performance in a high-radiation accelerator test beam facility

Digital cameras are critical diagnostics at test beam facilities. At FACET-II, there are over 100 digital cameras in operation. The 10 GeV electron beams cause high levels of radiation, which makes profile monitors susceptible to two types of failures: single-event upsets (SEU) and permanent death. The Camera Watchdog software was deployed to monitor and automatically power cycle cameras in the case of an SEU. The Camera Watchdog also updates the total number of reboots executed for each camera. Additionally, digital radiation monitors (RADFETs) have been installed at the locations of 10 cameras. We report on the findings from the study and discuss how they can be used to mitigate radiation damage to digital cameras.

Speaker: Sharon Perez (SLAC National Accelerator Laboratory)

16:00 Early Prediction of System Failures at Los Alamos Nuclear Science Center (LANSCE)

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, which the existing warning system does not. 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)

16:00 Efficient 6-dimensional phase space measurements and applications to autonomous monitoring at LCLS-II

Increasing the performance and capabilities of free electron lasers, such as LCLS-II, hinges on our ability to precisely control and measure the 6-dimensional phase space distribution of the beam. However, conventional tomographic techniques necessitate a substantial number of measurements and computational resources to characterize a single beam distribution, using many hours of valuable beam time. Novel diagnostic techniques are needed to significantly reduce the number of measurements required to reconstruct detailed, 6-dimensional beam features to enable feedback for precision beam shaping for accelerators and characterize unknown physical phenomena. In this work, we present a novel approach to analyzing experimental measurements using differentiable beam dynamics simulations and generative representations of 6-dimensional phase space distributions. We discuss developments in combining this work with advanced accelerator control algorithms and parasitic beam measurements to autonomously monitor the 6-dimensional phase space distribution of the beam at LCLS-II during accelerator operations.

Speaker: Ryan Roussel (SLAC National Accelerator Laboratory)

16:00 Experimental longitudinal emittance manipulation using laser-based photoionization in the Fermilab Linac

A series of simulations and beam studies were conducted at Fermilab’s linear accelerator to evaluate the effectiveness of longitudinal emittance control via laser-induced photoionization. While similar laser techniques have been employed at Fermilab to enhance injection and extraction efficiency into the Booster, the work presented here focuses on extending these methods to bunch-by-bunch manipulation. This approach utilizes fine-scale correction of the H- bunches’ longitudinal spatial distribution. In theory, loosely confined particles in longitudinal phase space contribute to emittance growth during acceleration. By selectively removing these outlying particles through laser scraping (H- + γ → H + e-), this growth can be reduced. This report presents experimental results from both symmetric and asymmetric longitudinal scraping of H⁻ bunches in the Fermilab linac, which were subsequently injected into Booster, and evaluates the broader applicability of this method for future high-intensity accelerator operations.

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

16:00 Fabrication Progress of an RF Beam Sweeper for Purifying Rare Isotope Beams

The RF beam sweeper at ATLAS facility plays a key role in the production of radioactive ion beams by enabling time-of-flight-based separation, thereby improving the purity of in-flight rare isotope beams. The current sweeper operates 6 MHz and achieves a maximum deflecting voltage of 55 kV. However, the enhanced beam capabilities introduced by the Argonne In-flight Ion separator (RAISOR) require a more versatile and higher-performance sweeper. To meet these needs, we are developing an upgraded RF sweeper capable of operating at 6 MHz and 12 MHz, with an improved deflecting voltage of 150 kV. The system employs a resonant circuit architecture incorporating electrode plates, an adjustable coil, and a mechanical sliding switch to facilitate frequency adjustment. In this talk, we will present design considerations and fabrication progress of the new RF sweeper, aimed at supporting next-generation rare isotope beam experiments.

Speaker: Aurora Cecilia Araujo Martinez (RadiaBeam Technologies (United States))

16:00 Facility-scale differentiable virtual accelerator at Fermilab

As the design complexity of modern accelerators grows, there is more interest in using advanced simulations and algorithms that have fast execution time or yield additional insights. One notable example are the gradients of physical observables with respect to design parameters, which are broadly useful in optimization and uncertainty analysis. The IOTA/FAST facility has been working on implementing and experimentally validating an end-to-end virtual accelerator test stand that is both fast and gradient-aware, allowing for rapid prototyping of new software and experiments with minimal beam time costs. We describe the selection and benchmarking of both physics and ML codes for linac and ring simulation, including obtaining parameter gradients with autodiff. We will also show the development of generic interfaces between surrogate and physics-based sections, and how the control interface is exposed as either a deterministic discrete event simulator or a fully asynchronous EPICS/ACNET soft IOC. We will also discuss challenges in model calibration and uncertainty quantification, as well as future plans to extend modelling to other Fermilab accelerators like PIP-II and Booster.

Speaker: Nikita Kuklev (Fermi National Accelerator Laboratory)

16:00 Fast adaptive neural control of resonant extraction at Fermilab

We present the development of a machine learning (ML) regulation system for third-order resonant beam extraction in the Mu2e experiment at Fermilab. Classical and ML-based controllers have been optimized using semi-analytic simulations and evaluated in terms of regulation performance and training efficiency. We compare several controller architectures and discuss the integration of neural control into an adaptive framework. In addition, we report progress on implementing low-latency, edge-based inference to enable deployment in hardware-constrained environments. This work demonstrates the feasibility and potential advantages of ML-based control for regulating complex, non-stationary systems, with applications extending beyond resonant extraction.

Speaker: Andrew Whitbeck (Fermi National Accelerator Laboratory)

16:00 Fast beam probe development for longitudinal bunch measurements at UC Davis Crocker Nuclear Laboratory Cyclotron

The UC Davis Crocker Nuclear Laboratory (CNL) operates a 76-inch Isochronous Cyclotron dating to the 1960s. Recent experiments have revealed unexplained beam behavior, which cannot be directly measured with the current diagnostics. Direct measurements of the beam in the Cyclotron are challenging due to the harsh environment, including high radiation, strong magnetic fields, RF interference, and spatial constraints. To address this, we are developing a novel beam probe capable of resolving longitudinal bunch structure across 16 positions simultaneously. The fast beam probe consists of a segmented fast plastic scintillator array coupled via fiber optics to external Silicon Photomultipliers (SiPMs), mounted on a radially translating probe. We report on the probe's performance from in-air tests at the general-purpose beamline. The results demonstrate sub-nanosecond resolution, consistent sensitivity across channels, and clear signatures of beam dynamics, establishing the system’s viability for measurements inside the CNL Cyclotron.

Speaker: Logan Knudson (University of California, Davis)

16:00 Field mapping and alignment procedure for new photoinjector solenoid magnets at the Argonne Wakefield Accelerator

The Argonne Wakefield Accelerator test facility will be upgrading the RF photoinjector with a new symmetrized RF photogun (named G4) in order to increase beam brightness and stability. In conjunction with G4, three new solenoid coils have been commissioned to replace the previous solenoids, with new considerations to preserve field symmetry and combat higher order modes within the coil that could reduce beam quality. We report here on the recent field mapping efforts on the solenoid, as well as discuss how these measurements can be used to aid alignment of the coils during the installation of the new G4 RF photogun.

Speaker: Alexander Ody (Argonne National Laboratory)

16:00 First results of the sXmap cavity field emission detection system from inside a cryomodule

Field emission (FE) has been one of the limiting factors in achieving high gradients in superconducting RF cavities. While the causes for FE are mostly known (contaminants on the inner cavity surface, dust, gases adsorbed…), identifying the exact location of field emitters has been a challenge. A detection system developed by Kyoto University has been developed to address this task, the sXmap system. This diagnostic device is made of inexpensive sensor strips that wrap around the iris of a multi cell SRF cavity that sense x-rays generated by FE. In this paper we will present the results obtained from a naked 6 cell SRF cavity in a vertical test configuration, and – for the first time – the results obtained from applying the sensor strips to an SRF cavity already installed inside a cryomodule in our test cave at ORNL – SNS.

Speaker: Paolo Pizzol (Oak Ridge National Laboratory)

16:00 FPGA implementation of a digital signal component separator and a disturbance compensator for the LANSCE 805 MHz solid-state high power RF amplifier

Because of aging, and product discontinuity, LANSCE is investigating the replacement of high power RF amplifiers. A promising candidate is the GaN solid-state power amplifier (SSPA). For a high drain voltage, the drain power dissipation of SSPA is increased as the operating efficiency becomes low. The outphasing technique provides high efficiency operation of the SSPA. The outphasing amplifier converts one Amplitude Modulation-Phase Modulation(AM-PM) signal to two PM only signals by the signal component separator(SCS), and these PM only signals are amplified by amplifiers linearly. The combination of the amplified PM only signals yields the linear amplification of the AM-PM input signal.
In this paper, a digital SCS (DSCS) in In-phase/Quadrature(I/Q) coordinate is proposed. The DSCS is implemented on the Field Programmable Gate Array(FPGA) based LANSCE digital low level RF (DLLRF) control system. In addition, a digital disturbance observer based compensator is implemented to detect and suppress the amplitude and phase disturbances existing on the RF forward paths. The performances of the DSCS and the disturbance compensator are verified on a low power testbench.

Speaker: Sungil Kwon (Los Alamos National Laboratory)

16:00 FPGA-based spill regulation system for the Muon Delivery Ring at Fermilab

The Muon to Electron Experiment (Mu2e) requires a uniform beam profile from the Muon Delivery Ring to meet their experimental needs. A specialized Spill Regulation System (SRS) has been developed to help achieve consistent spill uniformity. The system is based on a custom-designed carrier board featuring an Arria 10 SoC, capable of executing real-time feedback control. The FPGA processes beam pulses of approximately 200 ns every 1.695 microsecond, allowing for continuous monitoring of the extracted spill intensity through fast bunch integration. The system directly controls three quadrupole magnets, which work in conjunction with sextupole magnets to achieve third-order resonant extraction. Furthermore, the board interfaces with Fermilab’s Accelerator Control Network (ACNET), enabling operators to modify spill regulation settings in real-time via the control network while providing diagnostic waveforms. These waveforms help operators monitor the process and fine-tune the feedback mechanisms. This paper presents an overview of the board's architecture and its initial progress toward regulating beam extraction. This initial version of the regulation system aims to evaluate baseline performance to inform future system improvements.

Speaker: Jose Berlioz (Fermi National Accelerator Laboratory)

16:00 GTPSA.jl: A SciBmad interface to the generalised truncated power series algebra library

A full-featured interface package to the Generalised Truncated Power Series Algebra (GTPSA) library in MAD-NG has been implemented in the Julia programming language. GTPSA performs fast Taylor-mode automatic differentiation (AD) of functions to arbitrary orders in the specified variables and parameters. In particular, GTPSA excels at computing derivatives to high orders (>1) and high numbers of variables/parameters, making it an extremely powerful tool for use in optimization and in computing parametric Taylor maps. This Julia interface offers another simple way of using the GTPSA library, and will be used extensively in the SciBmad accelerator physics software ecosystem. The interface can also be easily called from Python, via the juliacall package. In this paper, we showcase features implemented in the interface package including performance enhancements, and present an example of integrating a GTPSA map using polymorphic integrators already implemented in Julia.

Speaker: Oleksii Beznosov (Los Alamos National Laboratory)

16:00 HED-Melt: A coupled framework for modeling high-energy-density conditions in accelerators

The high-brightness beams used by modern light sources and accelerators present a new challenge for machince protection. These beams, through impacts with beam intercepting components such as collimators, may generate high-energy-density (HED) conditions capable of causing significant damage to machine components. One significant issue in studying these dynamics is that lack of simulation tools which capture all of the physics present. Particle tracking and particle-matter interaction codes are widely used in accelerator design but the is not significant interfacing between the two and few codes are available to simulate the melting and vaporization seen in some beam strikes. HED-Melt (High Energy Density Modeling of ELectron beam impacts Toolkit) is a framework of coupling three physics codes, elegant, fluka, and flash to model the effects of HED conditions in various accelerators components. The toolkit automatically interfaces between the three codes to run a full-physics simulation of HED conditions for a user-defined machine lattice.

Speaker: Austin Dick (Argonne National Laboratory)

16:00 High-Throughput, Low-Latency X-ray Characterization for Attosecond XFEL Diagnostics: A Heterogeneous Approach

SLAC’s LCLS-II delivers attosecond X-ray pulses at high repetition rates, targeting 1 MHz. Meeting this challenge requires hardware-optimized, low-latency pipelines for real-time, single-shot diagnostics. We present a heterogeneous data processing approach for the Multi-Resolution Cookiebox (MRCO) detector—an array of 16 electron time-of-flight spectrometers with tunable flight lenses and dedicated amplifiers for time, angle- and energy-resolved spectroscopy.* MRCO full data pipeline integrates analog-digital co-design with FPGA-accelerated algorithms** and edge-deployed machine learning to perform denoising, spectral feature extraction, and temporal reconstruction of the X-ray pulses from LCLS-II.*** FPGA-optimized peak finding algorithms** enable online feature extraction while component neural networks—including long short-term memory models and ResNets—are trained on synthetic data to recover attosecond temporal substructure of the X-ray pulses.*** By co-optimizing algorithm design with traditional and emerging hardware (e.g., Groq inference cards, FPGAs), we achieve high-throughput, low-latency inference suitable for shot tagging and feedback. These efforts represent a state-of-the-art step toward closing the gap to MHz operation and highlight the growing need for deeper algorithm–hardware co-design in attosecond XFEL science.

Speaker: Jack Hirschman (Stanford University)

16:00 Impedance modeling of in-vacuum undulator with Gaussian process

The impedance of in-vacuum undulators (IVUs) significantly affect the broadband impedance and, consequently, the beam dynamics in storage rings. During the IVU design phase, numerous iterative discussions between physicists and engineers are required, often involving extensive simulations of the complete 3D geometry, a few meters long, using limited computational resources. In this paper, we propose training a Gaussian process model with limited simulation data to emulate the physical model. We compare the predictions of the trained model to the simulation data and explore its application in optimizing the IVU design.

Speaker: Minghao Song (Brookhaven National Laboratory)

16:00 Implementation of a 1550-nm laser system for beam characterization at the Argonne Wakefield Accelerator

Accurately recording an electron bunch’s longitudinal profile is an important diagnostic for wakefield accelerators employing shaped bunches to increase transformer ratios.  Electro-optic sampling of terahertz radiation from the bunch is an attractive approach due to its non-destructive nature. In preparation for future characterization experiments, the Argonne Wakefield Accelerator test facility has recently installed a 1550 nm laser system, including the necessary support systems to synchronize with the photoinjector laser system at 81.25 MHz. We report here on the initial installation and synchronization demonstrations.

Speaker: Alexander Ody (Argonne National Laboratory)

16:00 Implementation of a temperature and density monitoring diagnostic for the LANSCE negative ion source

We report on adding a muti-wavelength emission and absorption diagnostic to the Los Alamos Neutron Science Center (LANSCE) H− ion source, a filament/arc driven, multi-cusp, surface conversion system. In this work we are better quantifying our runtime and source recycle processes. The LANSCE source is used in repeated four-week run cycles during the annual six-month run period. Here, we test the hypothesis that real-time monitoring of the plasma temperature and cesium density will provide feedback information to increase run cycle time, optimize H− current, and monitor the source’s health. We have installed system with fiber transport for monitoring the Hα Balmer line absorption strength of excited state hydrogen at 656 nm and the D2 absorption line of cesium at 852 nm. Our measurement and fiber transport to/from the active source provides a nonintrusive method for extracting data from the source’s 750 kV high voltage environment. Collection of TLDS absorption and emission lines from excited states are incorporated into the data collection scheme with a series of narrow-band dichroic mirrors. Our design of a sweeping TLDS allows for collection of emission and absorption data within the same sub-millisecond plasma arc pulse, and the combination of these measurements allows us to monitor the generating hydrogen plasma temperature and cesium density during ion source conditioning and operations.

Speaker: Charles Rohde (Los Alamos National Laboratory)

16:00 Improve beam brightness with bayesian optimization at the AGS booster injection at BNL

Alternating Gradient Synchrotron (AGS) and its Booster serve as part of the injector compound for RHIC and the future EIC at Brookhaven National Laboratory. Injection and early acceleration processes set maximum beam brightness for the collider rings. Such processes have many control parameters and are traditionally optimized empirically by operators. In an effort to streamline the injection processes with machine learning
(ML) techniques, we develop and test a Bayesian Optimization (BO) algorithm to automatically tune the Linac to Booster (LtB) transfer line magnets to maximize beam brightness after injection into the Booster. We present experimental results that demonstrate BO can be applied to optimize Booster injection efficiency.

Speaker: Weijian Lin (Brookhaven National Laboratory)

16:00 Instrumentation for a prototype fusion propulsion system

A prototype colliding beam accelerator has been fabricated for the study of a fusion-based propulsion concept for interplanetary exploration. The purpose of this prototype is to demonstrate collider luminosities commensurate with the requirements of this application. While fusion fuels such as p/Li7 and He3/He3 would generate the required thrust characteristics, this prototype currently employs deuterium. Because neutrons are produced via DD fusion with a peak cross section of 0.1 barns, even modest initial luminosities yield event rates suitable for real-time measurements and lifetime monitoring. The proposed luminosity monitor is based on neutron moderation and absorption and subsequent gamma-ray detection. Sodium chloride serves as the moderator, with most neutrons absorbed by chlorine-35 nuclei having a thermal neutron absorption cross section of 43.6 barns. The collider is a linear device employing electrostatic axial confinement and radial focusing. A combination of destructive and nondestructive sensors are employed to monitor various beam parameters such as intensity, energy spectrum, transverse tunes and halo density distribution.

Speaker: Grace Bittlingmaier (Beam Alpha Incorporated)

16:00 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))

16:00 Integrating simulation and machine learning for Proton Storage Ring beam analysis

The Proton Storage Ring (PSR) at the Los Alamos Neutron Science Center (LANSCE) accumulates a 625-μs-long beam and compresses it into a 290-ns-long (base-to-base) short pulse for delivery to the Lujan Center. Due to its high-intensity operation, the PSR also functions as a highly-sensitive mass spectrometer for the entire accelerator complex. Changes in PSR beam losses are more responsive to linac drifts than any other diagnostic system, making continuous monitoring and characterization of the PSR critical to overall performance.
Currently, PSR operation is primarily guided by beam loss signals, while key physics parameters—such as the betatron tune, closed orbit, and injection offsets—are typically measured only once per day. Furthermore, Beam Position Monitors (BPMs) can only provide meaningful data a single 290-ns-long injection, requiring dedicated machine time and resulting in operational downtime.
However, recent upgrades to both the data acquisition and chopper systems now enable continuous measurements during standard operation. In this work, we employ a Convolutional Neural Network (CNN) trained on simulated data to infer critical beam parameters in real-time. This approach will be tested and implemented during the 2025 run cycle to enable online monitoring and improved control of PSR beam dynamics.

Speaker: Christopher Leon (Los Alamos National Laboratory)

16:00 Investigation of IPM profile changes with variations in the applied electric field

Variations in the applied electric field in the Ionization Profile Monitor (IPM) affects the time of flight for the ionized particles (primarily electrons) which could affect the measured transverse beam profile. In addition, the applied electric field may affect the space charge of the ionized electrons inside the IPM. In this paper, we present an experimental beam study of RHIC IPM profiles, examining the effect of varying applied electric fields. Such a beam study will be helpful to enhance the design of the future IPMs for the Electron-Ion Collider. We analyzed horizontal and vertical profiles of gold and proton beams, comparing measured data with simulations along with the procedure we used for measurement. Potential causes for discrepancies between measured and simulated results are also discussed.

Speaker: Medani Sangroula (Brookhaven National Laboratory)

16:00 Lifetime extension of legacy CEBAF LLRF hardware

A significant portion of the Low-Level Radio Frequency (LLRF) hardware in Jefferson Lab’s CEBAF is from the original construction of the facility using 1980’s CAMAC technology. Of the fifty-three zones in CEBAF, thirty-six of them are legacy hardware. The age of the legacy system has led to difficulties in maintaining the hardware due to parts going obsolete without suitable drop in replacements. Continued operation of the legacy system is required as the installation of LLRF 3.0 systems is costly and cannot be completed in a short period of time with the available resources. The most pressing failure in the legacy system was a failing buffer card, which is responsible for communication between the EPICs network and individual RF control modules. A new buffer card was designed as a transparent, drop in, replacement so that upgrades are simply a matter of swapping the existing legacy hardware. This buffer card upgrades a single point failure component and promises to extend the operable lifetime of CEBAF’s legacy systems.

Speaker: Michael Geesaman (Thomas Jefferson National Accelerator Facility)

16:00 Low-charge, high-resolution beamline preparation for the nanopatterned microbunching experiment at Argonne Wakefield Accelerator

The emittance exchange (EEX) beamline at the Argonne Wakefield Accelerator (AWA) is designed to transfer properties of an electron beam phase space between the transverse and longitudinal planes. Recently, it has been proposed this beamline could be used to convert a microscale transverse modulation created by a TEM grid into a microbunch train in the longitudinal plane. Such a technique would be useful for obtaining nano-scale microbunching that does not rely on the sensitive process of FEL gain. This new approach has been proposed to enable development of a compact free-electron laser at Arizona State, greatly reducing size and cost compared with existing short wavelength FELs. To perform an exploratory demonstration of this concept at AWA, this experiment requires low normalized emittance (~50 nmrad), low charge (~1pC) electron bunches, and transverse diagnostics with high-resolution (1-3 microns) and high-light-collection to resolve the modulation on the electron beam. This report will give a progress update on preparing the necessary beams and diagnostics at AWA for an emittance exchange experiment that would produce 100s of nm scale microbunches.

Speaker: Rachel Margraf-O'Neal (Argonne National Laboratory)

16:00 Machine learning assisted Bayesian calibration of accelerator digital twin from orbit response data

Digital twins of particle accelerators are used to plan and control operations and design data collection campaigns. However, a digital twin relies on parameters that are hard to measure directly, e.g., magnet alignments, power supply transfer functions, magnet nonlinearities, and stray fields. These parameters can be constrained by beam position and profile measurements. We use Bayesian statistical inference to estimate
the parameters, and their uncertainties, probabilistically by calibrating the Bmad digital twin to beam measurements. The inference is computationally accelerated using a machine learning emulator of the physical accelerator digital twin trained to a perturbed-parameter ensemble of Bmad simulations. The result is a joint posterior distribution over parameters (control currents, individual magnet transfer function coefficients, and beam monitor errors) which is propagated to uncertainties in predicted beam positions and profiles, which we validate against beam responses measured at the AGS booster at Brookhaven National Laboratory.

Speaker: Weijian Lin (Brookhaven National Laboratory)

16:00 Machine learning at the Spallation Neutron Source accelerator and target

We describe the ongoing efforts to apply Machine Learning techniques to improve the performance of our accelerator and target. Specially, we are looking to minimize halo beam losses in the absence of a proper physics model, automatically detect and log anomalies in the target support systems such as cooling, and detect and prevent errant beam pulses in the linac. We also describe the infrastructure we use to acquire and stream data to the GPU cluster for training, our code development cycle, and edge computing for model inference. To minimize halo beam losses, we use a Reinforcement Learning technique tested on a virtual accelerator. The target anomaly detection is trained on archived data using incomplete physics models and is made part of the existing target reporting system. The errant beam prevention analyzes beam current and beam phase waveforms as well as accelerator configuration data to predict errant pulses. We also develop continual learning to adapt to changes in the accelerator.

Speaker: Dr Willem Blokland (Oak Ridge National Laboratory)

16:00 Machine Learning-Based Reduced-Order Encoding of 6D Particle Phase Space for Accelerators

State-of-the-art simulation of accelerator facilities such as Linac Coherent Light Source (LCLS) involves modeling charged particle dynamics in six-dimensional (6D) phase space under the influence of nonlinear collective effects, including space charge and coherent synchrotron radiation (CSR). Accurately capturing these effects typically requires simulating hundreds of thousands of macroparticles, resulting in significant computational cost in both time and memory. This becomes a bottleneck for downstream tasks such as uncertainty quantification (UQ), model calibration, optimization, and control, which require multiple simulations. These challenges motivate the development of low-dimensional, lightweight surrogate models for accelerators, capable of enabling rapid predictions. However, the high dimensionality of the 6D phase space poses a major obstacle. In this work, we present a machine-learning-based approach for reduced-order encoding of high-dimensional particle phase-space data using autoencoders. In our approach, we learn low-dimensional latent representations that preserve the geometric and physical structure of the original beam distribution, enabling effective compression while retaining essential features. We evaluate this approach on datasets generated using the Bmad particle tracking library, demonstrating its potential as a foundation for fast surrogate modeling, differentiable simulations, and accelerator optimization workflows.

Speaker: Indranil Nayak (SLAC National Accelerator Laboratory)

16:00 Machine learning-driven computations of 3D Coherent Synchrotron Radiation

Calculating the effects of Coherent Synchrotron Radiation (CSR) is one of the most computationally expensive tasks in accelerator physics. Here, we use convolutional neural networks (CNN's), along with a latent conditional diffusion (LCD) model, trained on physics-based simulations to speed up calculations. Specifically, we produce the 3D CSR wakefields generated by electron bunches in circular orbit in the steady-state condition. Two datasets are used for training and testing the models: wakefields generated by three-dimensional Gaussian electron distributions and wakefields from a sum of up to 25 three-dimensional Gaussian distributions. The CNN's are able to accurately produce the 3D wakefields $\sim$250-1000 times faster than the numerical calculations, while the LCD has a gain of a factor of $\sim$34. We also test the extrapolation and out-of-distribution generalization ability of the models. They generalize well on distributions with larger spreads than what they were trained on, but struggle with smaller spreads.

Speaker: Christopher Leon (Los Alamos National Laboratory)

16:00 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)

16:00 Micro-fabricated photoconductive sampling devices for electron beam field measurements

Achieving high-precision, in situ measurements of electric fields is a critical challenge in ultrafast science and accelerator diagnostics. We are developing an approach using photoconductive sampling with micro-fabricated devices to map electron beam fields with unprecedented spatiotemporal resolution. This technique enables the first direct 3D vector field measurements of electron beams, offering valuable insights into collective effects such as coherent synchrotron radiation and other phenomena impacting beam quality. These low-cost, highly flexible devices present a pathway to enhancing our understanding of beam dynamics and reducing transient effects that degrade beam quality. The devices will be initially tested on the ultrafast x-ray beamline at LCLS, and could be adapted as a diagnostic tool across other SLAC user facilities. Beyond diagnostics, this approach will also help in advancing studies of ultrafast charge transport and unlocking new science in attosecond solid-state physics.

Speaker: Veronica Guo (Stanford University)

16:00 Mitigating IDVC thermal deformation with mechanical constraint for reliable ID minimum gap operation

Premature activation of the insertion device (ID) minimum-gap limit switches was observed during beamline commissioning at the Advanced Photon Source Upgrade (APSU). This issue was traced to vertical deformation of the insertion device vacuum chamber (IDVC) due to temperature differences with its strongback. Direct measurements of temperature and vertical displacement of IDVC in a selected sector of the APS storage ring confirmed this effect, and simulations successfully reproduced the thermal deformation mechanism. To address the issue, we developed a simple mechanical constraint to limit the vertical displacement, rather than actively compensating for the temperature difference through enhanced heat transfer. This paper reports the investigations, proposed mechanical solution, simulation, and measurement validation after its installation. Post-installation tests successfully demonstrated its effectiveness, allowing the IDs to reach the minimum gap without triggering the limit switch.

Speaker: Wei Li (Argonne National Laboratory)

16:00 Modeling of a high-current injector for beam optimization

End-to-end simulations of intense relativistic electron beams generated by linear induction accelerators (LIA) often involve two-step processes whereby the beam creation is simulated using particle-in-cell (PIC) methods before a handoff to less computationally-expensive methods, e.g. beam envelope solvers, to determine sufficiently robust beam tunes. Because of this hand-off, fields that affect the PIC simulation of the A-K gap region are usually untouched during the tuning process. To allow for magnetic guide field optimization including magnets close to the A-K gap, a machine learning model of an LIA injector system is under development to allow for rapid end-to-end simulations of the electron beam for use in beam optimization problems, e.g. automated magnetic transport field tuning.

Speaker: Evan Scott (Nevada National Security Site)

16:00 Modernizing wire scan diagnostics for reproducible, real-time beam measurements through a modular Python middle layer integrated with EPICS

As part of a broader effort to modernize beam diagnostics at SLAC, we are developing a new middle-layer application to support wire scan measurements using Python. This tool is designed to replace aging MATLAB GUIs with a streamlined framework that interfaces directly with EPICS and Beam Synchronous Acquisition systems. The middle layer manages the complete wire scan workflow while emphasizing modularity, reproducibility, and integration with existing controls infrastructure. This talk will cover the system architecture, practical implementation details, and lessons learned in deploying a diagnostic tool suited to the high-throughput, real-time needs of accelerator operations.

Speaker: Tyler Kabana (SLAC National Accelerator Laboratory)

16:00 Nested Extremum Seeking for Virtual Diagnostics and Control

Machine learning methods have been increasingly used to model complex physical processes that are difficult to address with traditional approaches, especially when these processes exhibit temporal dynamics or require real-time implementation. The linear accelerator (LINAC) at the LANSCE facility is one such system. While a high-resolution simulation tool, HPSim, exists, the complexity and high computational costs of the simulation, combined with the spatiotemporal variability of the LINAC and limited diagnostic measurements, creates challenges for real-time operation. These challenges can be mitigated by developing fast surrogate machine learning models to provide virtual diagnostics and enable control. However, the highly expressive nature of machine learning models often results in opaque representations, complicating their use in control applications. Control design and tuning are significantly simplified when the system dynamics are captured by a more interpretable, parsimonious model. This study seeks to harness the power of machine learning while applying traditional system identification techniques to develop models that are both effective for control and computationally efficient.

Speaker: Brad Ratto (Los Alamos National Laboratory)

16:00 New ACE3P capabilities and code integration of ACE3P with Geant4 and Lume

The Advanced Computational Electromagnetic 3D Parallel simulation suite (ACE3P), developed by SLAC National Accelerator Laboratory, is a state-of-the-art multi-physics toolkit designed for virtual prototyping of accelerator and RF components. Leveraging over two decades of development, ACE3P integrates advanced physics modeling, including thermal and structural modeling, capabilities with scalable numerical algorithms to deliver cutting-edge simulations. The suite, comprised of seven application modules, utilizes high-order curved finite element methods to achieve high accuracy while enabling fast simulations for large-scale problems.
Two recent advancements include the integration with Geant4, for radiation studies and positron source generation, and the development of LUME-ACE3P, built on the Python framework of the LUME project*, which streamlines parameter sweeps and optimization tasks. Furthermore, recent code optimizations have increased the performance of ACE3P for large-scale computations on modern supercomputers. We present a real accelerator project study with ACE3P to demonstrate its scalability and efficiency conducted on NERSC supercomputers.

Speaker: David Bizzozero (SLAC National Accelerator Laboratory)

16:00 Online accelerator modeling with two controls systems at FACET-II

FACET-II is a unique experimental facility housed in 1 km of the original Stanford Linear Accelerator tunnel. Multiple generations of hardware are still in use, as are two generations of software controls. A majority of subsystems (RF, magnets, timing, etc.) have their controls split across both ecosystems. Three software layers, including a newly-developed online modeling infrastructure, bridge this gap to form a unified high-level abstraction of the accelerator used for data analysis and as a foundation to develop control-room physics applications. We discuss the implementation of this infrastructure and some downstream programs.

Speaker: Zack Buschmann (SLAC National Accelerator Laboratory)

16:00 Online multi-objective Bayesian optimization of injection efficiency and beam lifetime with skew quadrupoles at NSLS-II

At NSLS-II, the vertical emittance of electron beam is typically blown up to ~30 pm with a coupling wave to increase beam lifetime during user operation. As more and more insertion devices are added to the storage ring, injection efficiency to the ring drops noticeably in certain machine states, apparently due to degraded dynamic apertures. To help alleviate this issue, we have recently performed online multi-objective Bayesian optimization to increase injection efficiency while maintaining beam lifetime, by adjusting the strengths of 15 skew quadrupoles in non-dispersive sections. We report the results of this optimization effort.

Speaker: Yoshiteru Hidaka (Brookhaven National Laboratory)

16:00 Online optimizations of NSLS-II Linac and Linac-to-Booster beam lines using machine learning methods

The NSLS-II is a cutting-edge 3 GeV storage ring light source around the world. The electron beam is initially accelerated in a linear accelerator to an energy of 170 MeV and subsequently accelerated in a booster synchrotron to a beam energy of 3 GeV. Therefore, the performance of the Linac and the Linac-to-Booster beam lines is imperative for beam injection to the booster. Online optimization is an effective solution to improve accelerator performance when there is degradation. This paper presents the results of online optimization employing a machine learning method.

Speaker: Minghao Song (Brookhaven National Laboratory)

16:00 Oscillation Data Analysis during the LCLS-II Commissioning at SLAC

Analyzing the betatron oscillation of a beam is mainly used to find focusing errors in the lattice, like quadrupole errors. The generated trajectory differences can be compared with the design lattice or the current machine lattice where some magnets have been changed for different purposes or accidentally. Each method has different advantages and disadvantages like finding a quadrupole which got turned off by mistake won't be discovered with the current lattice method, while matching quadrupoles errors (which get tuned away from design) are harder to identify with the design lattice comparison. Besides lattice errors BPM (Beam Position Monitor) problems can be found too. Interpreting the data can have many pitfalls, some will be explained.

Speaker: Franz-Josef Decker (SLAC National Accelerator Laboratory)

16:00 Performance optimization of the IOTA duoplasmatron proton source

We present results from online optimization studies of a duoplasmatron ion source designed to produce 50 keV protons for acceleration to 2.5 MeV and subsequent injection into the Integrable Optics Test Accelerator (IOTA) at Fermilab. Using a Bayesian exploration technique, we developed multi-parameter models of the source’s proton current and employed these models to optimize its performance. Depending on the spectrometer configuration used to isolate the proton beam and the chosen optimization objective, we identified three candidate operating points, achieving normalized 50 % emittances between 0.57 μm and 1.3 μm and a maximum proton current of 14.5 ± 0.6 mA.

Speaker: Michael Wallbank (Fermi National Accelerator Laboratory)

16:00 Phase space reconstruction of beams affected by coherent synchrotron radiation

Coherent synchrotron radiation (CSR) is a limiting effect in linear accelerators with dispersive elements due to its contribution to projected transverse emittance growth. This effect becomes a limitation for highly compressed beams. Even though CSR-induced projected emittance growth has been widely studied, conventional measurement techniques are not detailed enough to resolve the multi-dimensional structure of the beam, namely the different translations and rotations of transverse phase space slices throughout the longitudinal coordinate. In this work, we use a state-of-the-art method to reconstruct the phase space of a beam affected by CSR at the Argonne Wakefield Accelerator Facility. This detailed, efficient and multi-dimensional phase space reconstruction method enables better understanding of the CSR effects in a double dogleg where shielding is limited.

Speaker: Juan Pablo Gonzalez-Aguilera (University of Chicago)

16:00 Physics considerations for a harp system design at the Second Target Station of the Spallation Neutron Source

A harp system is being developed for monitoring proton beam profile direct upstream of the proton beam window at the Second Target Station of the Spallation Neutron Source, Oak Ridge National Laboratory. It consists of two sensor planes which have arrays of thin conducting wires aligned vertically and horizontally, respectively. It monitors beam profiles in two transverse directions to the beam axis by measuring the net-charge depositions in the sensor wires, which are caused by ejection of secondary electrons and delta rays driven by electromagnetic interactions with high-energy protons. The net charge deposition in a sensing wire linearly correlates with the number of incident protons on it. This correlation is perturbed when the wire interacts with secondary electrons and delta rays originating from beam-matter interactions in neighboring wires, PBW and residual gases. In this paper, we analyze the physical phenomena that affects the measurement uncertainties of the harp using particle transport simulations.

Speaker: Yong Joong Lee (Oak Ridge National Laboratory)

16:00 Physics-coupled 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 (Fermi National Accelerator Laboratory)

16:00 Preliminary study of auto-differentiation algorithm in beam dynamics with stochastic process

Modern particle accelerator optimization requires sophisticated computational methods to address the inherently stochastic nature of beam dynamics. This research develops a framework applying AD to SDEs that specifically addresses beam dynamics challenges in particle accelerators, focusing on accurately modeling and optimizing beam behavior in regimes dominated by stochastic processes. By incorporating key physical phenomena such as synchrotron radiation, wakefield effects, and quantum excitation, the framework aims to provide auto differentiation on the figure of merit of the phase space evolution and beam dynamics. The methodology will enable effective optimization method in a dynamic system with stochastic process.

Speaker: Christian Ratcliff (Facility for Rare Isotope Beams)

16:00 Progress report on the upcoming drive beam photoinjector upgrades at the Argonne Wakefield Accelerator

The Argonne Wakefield Accelerator test facility is dedicated to research on advanced acceleration, beam manipulation, and beam production. With a focus primarily in the development and testing of high-gradient wakefield-accelerator structures, the drive beamline RF photoinjector is capable of delivering high charge (100s of nC) 65 MeV electron bunch trains. We present the planned upgrades to the drive photoinjector aimed at increasing both beam brightness and stability, and report on the current progress for the first phase of the upgrade and upcoming RF gun installation.

Speaker: Alexander Ody (Argonne National Laboratory)

16:00 Proposal to measure bunch lengths using a pulse dilation photomultiplier tube

Electron bunches in storage rings are typically short (~100 ps) and separated by long periods of time (>2 ns). A pulse dilation photomultiplier tube offers a new way of measuring high bandwidth optical pulses using low bandwidth oscilloscopes. Experiments performed by others have demonstrated a temporal resolution of 12 ps, meeting requirements for electron bunches expected for the Advanced Photon Source Upgrade. Compared to electrooptical streak cameras, we think that this may be a preferred technique for measuring the longitudinal profile of bunches in electron storage rings.

Speaker: Kent Wootton (Argonne National Laboratory)

16:00 Proposal to streak optical pulses using a solid state optical deflector

Streak cameras are flexible cameras used to measure the temporal profile of optical pulses. Streak cameras have been employed to measure the longitudinal beam profile on accelerators around the world. In the present work, we highlight a potential alternative to a new streak camera. We consider particularly linear (Pockels) and quadratic (Kerr) electro-optical nonlinearity solid-state streaking systems. Of the possible solid state systems, we motivate the potential advantages of a Potassium Tantalum Niobate KTa1-xNbxO3 crystal as a photon beam deflector to measure the longitudinal profiles of electron beams in accelerators.

Speaker: Kent Wootton (Argonne National Laboratory)

16:00 Recent Beam Test Results of RadiaBeam’s Multi-Dimensional Bunch Shape Monitor at SNS facility

Accurate measurement of longitudinal beam parameters is critical for optimizing high-intensity linear accelerators, yet remains difficult for non-relativistic proton and ion beams. The Bunch Shape Monitor (BSM) is a diagnostic device designed to measure the longitudinal profile of charged particle beams. It operates by inserting a thin wire into the beam path, which emits secondary electrons upon interaction with the main beam. These electrons retain the temporal charge distribution information of the primary beam, which is then converted into a spatial distribution using an RF deflector. Existing BSM models suffer from low electron collection efficiency and are limited to one-dimensional measurements of the longitudinal phase coordinate. To address these limitations, RadiaBeam has developed a next-generation BSM prototype featuring a refined focusing field between the target wire and entrance slit to increase secondary electron collection efficiency, an improved RF deflector for greater temporal resolution and linearity, and an upgraded movable mechanism to enable both longitudinal and transverse profile measurements. In this talk, we will present recent beam test results performed at the Spallation Neutron Source (SNS), highlighting improvements to the BSM based on insights from initial experimental data. Additionally, we will discuss further modifications to the BSM needed for compatibility with other facilities, such as PIP-II at Fermilab.

Speaker: Aurora Cecilia Araujo Martinez (RadiaBeam Technologies (United States))

16:00 Resolution enhancement of double-differential spectrometer images

By pairing the effects of a transverse deflecting cavity and dipole magnet, a beam's longitudinal phase space (LPS) can be imaged on a screen. However, the emittance of the beam, chromatic focusing, and other effects are convolved into the resulting screen image, functionally blurring it, reducing the fidelity of the LPS measurement. Here, we explore the use of both conventional, space-variant deconvolution as well as machine-learning approaches to better resolve the LPS.

Speaker: Nathan Majernik (SLAC National Accelerator Laboratory)

16:00 Resonant cavity for quadrupole moment measurements of heavy ion beams

Non-invasive and fast beam emittance measurement is highly demanded for accelerated multi-charge-states heavy ion beams. The driver linac of the Facility for Rare Isotope Beams is the first accelerator intended to accelerate multiple charge states of stripped heavy ion beams and deliver up to 400 kW to the isotope production target. Emittance measurements of, for example, five charge states of uranium beam using conventional wire profile monitors take more than an hour in one location and add up to a few hours throughout the linac. This work presents design studies for a resonant cavity monitor capable of instantaneous measurement of the quadrupole moment of the beam distribution. Coupling with the beam and signal acquisition system, the separation between monopole, dipole, and quadrupole modes of the cavity are discussed.

Speaker: Alexander Plastun (Facility for Rare Isotope Beams)

16:00 RF characterization of a cryogenic X-band cavity beam position monitor for superconducting undulator applications at SLAC

Superconducting undulators (SCUs) have gained significant interest due to their advantages over permanent magnet undulators, including the ability to achieve higher magnetic fields and shorter periods, leading to enhanced photon energy gain. As part of the SCU project at SLAC, an X-band cavity beam position monitor (BPM) has been designed and fabricated. This BPM plays a crucial role in the SCU assembly ensuring precise beam alignment with sub-micron resolution. The BPM incorporates two rectangular cavities for X- and Y-position measurements and a cylindrical reference cavity, all housed within a single copper block. Each cavity is separated by approximately 30 mm, which eliminates crosstalk between channels. The design of each cavity includes a single WR-75 waveguide port with a ceramic window as vacuum-air interface for out-coupling the EM field from the cavity to the external circuit. Additionally, each cavity is equipped with a tuner pin for resonant frequency adjustments. In this work, we report on the RF characterization of the BPM cavities conducted at both room and cryogenic temperatures. A consistent resonant frequency shift of approximately 37 MHz was observed when cooling the cavities from room temperature to 40 K, which is the nominal operating temperature within the undulator cryomodule. These measurements validate the predictions made during the BPM design phase through simulations. We also discuss future plans and possible applications beyond the SCU project.

Speaker: Konstantin Kruchinin (SLAC National Accelerator Laboratory)

16:00 Rotor-based multileaf collimator for beam shaping

Multileaf collimators (MLC) are versatile tools for beam shaping, both transversely or, when used in conjunction with an emittance exchange (EEX) beamline, longitudinally. The requirement for ultra-high vacuum compatibility introduces significant constraints on the design of a MLC. Here, we present a novel design for a MLC based on stacks of rotors with angularly dependent radii. The use of tabs and slots allow dozens of these rotors to be positioned using a single vacuum feedthrough, dramatically reducing complexity over independently positioned leaves. We discuss other design elements and also the considerations arising from having a volumetric rather than planar beam mask.

Speaker: Nathan Majernik (SLAC National Accelerator Laboratory)

16:00 SEM grid testing at NLCTA in BeamNetUS program

We report on the performance of a secondary electron monitor (SEM) grid for determining the transverse profile of an MeV range electron beam tested at SLAC National Accelerator Laboratory’s NLCTA facility. When inserted into the path of the electron beam, secondary electron emission results in a measurable current on the wires that make up the grid. We present measurements using this technique to reconstruct the beam profile. The SEM grid was designed and built by a team of Harvey Mudd College (HMC) undergraduate students and tested at SLAC’s NLCTA facility in collaboration with NCLTA staff as part of the BeamNetUS program. This SEM grid, developed for real-time measurements of an MeV scale electron beam, could have applications in industry and medicine.

Speaker: Nebiyu Samuel (Harvey Mudd College)

16:00 Status of longitudinal bunch-by-bunch feedback system at the upgraded Advanced Photon Source

The upgraded Advanced Photon Source (APS) is using twelve Radio Frequency (RF) cavities from the original APS RF system to compensate for beam energy loss. Undamped higher order modes (HOMs) from these cavities pose a risk of instability under the new APS conditions. Dimtel iGp12 processor-based bunch-by-bunch Longitudinal Feedback (LFB) system is developed to address longitudinal coupled-bunch instabilities caused by HOMs. These instabilities are exacerbated by the reduced synchrotron frequency and faster growth rates in presence of bunch lengthening system. The mitigation strategy involves initially reducing growth rates through precise cavity temperature tuning, followed by employing the LFB system to effectively manage residual growth rates. Resonance cavity temperatures of the HOMs have been characterized under APS conditions, providing a reference for tuning in the upgraded APS operation. The LFB system is designed to operate in both phase and energy sensing modes. This paper presents the feedback configuration, initial commissioning results with phase and energy sensing modes, and the feedback setup for operations.

Speaker: Pavana Kallakuri (Argonne National Laboratory)

16:00 Surrogate model for third-integer resonance extraction at the Fermilab Delivery Ring

We present an ongoing work in which a surrogate model is being developed to reproduce the response dynamics of the third-integer resonant extraction process in the Delivery Ring (DR) at Fermilab. This is in pursuit of smoothly extracting circulating beam to the Mu2e Experiment’s production target, whereby the goal is to extract a uniform slice of the circulating 1e12 protons in the DR over 25,000 turns (43 ms). The DR contains 3 harmonic sextupoles that excite a third-integer resonance and three fast, tune-ramping quadrupole magnets that drive the horizontal tune towards the 29/3 resonance. In our initial work, the surrogate model trains on a semi-analytical simulation provided in the same format as live data. Using Reinforcement Learning (and other potential ML methods), the trained surrogate acts as the “environment” in which a simple ML control agent could learn to dynamically adjust the quadrupole ramp at 430 break points within the 43 microsecond spill window. The controller will be hosted on a dedicated Arria 10 FPGA. In this work, we report the accuracy and fidelity of the surrogate model in comparison to the response dynamics of the physics simulator.

Speaker: Aakaash Narayanan (Fermi National Accelerator Laboratory)

16:00 Synchrotron frequency measurements using bunch by Bunch longitudinal feedback system in a storage-ring with higher harmonic cavity

The upgraded Advanced Photon Source (APS) features a 1408 MHz superconducting Bunch Lengthening System (BLS) to improve beam lifetime and emittance. The main RF system is significantly affected by ambient 60 Hz-harmonics noise, complicating the measurement of synchrotron frequency under varying higher harmonic cavity conditions. To address this, using Dimtel iGp12 processor-based longitudinal feedback system we developed two methods to measure synchrotron frequency effectively. Our approach involves driving multi-bunch beam modes by considering a span for synchrotron frequency sideband and analyzing mode amplitude changes across the sweep frequency range. The "slow" method scans fixed drive frequencies within a range, recording the beam response at each frequency. The “fast” approach drives the beam with a broadband chirp signal and analyzes the resulting single mode spectrum data. Both methods are tested during beam studies. Synchrotron frequency changes are measured in two setups: First, adjusting BLS voltage manually while keeping beam current constant. Second, BLS voltage varying as a function of decaying beam current. This paper presents, details of the measurement procedure and results from the beam-based machine studies.

Speaker: Pavana Kallakuri (Argonne National Laboratory)

16:00 The beamline steering software for the APS Upgrade (APS-U) Accelerator Storage Ring

A new beamline steering software system is being developed for the Advanced Photon Source Upgrade (APS-U) accelerator storage ring. This system comprises three main components: The main steering server, which performs the actual beamline steering; The beamline steering server, which monitors users' steering requests and forwards them to the main steering server; And an operational steering application. The underlying steering functionality is managed by the Data Acquisition (DAQ) PV Group module. This module includes utilities for controlling and monitoring multiple scalar Channel Access (CA) Process Variables (PVs), combining their values into a single PV data object that is served on a specified PVA channel. Users can interact with the PV group either via PVA or through a set of control CA PVs hosted directly by the PV group controller. The new steering software is compatible with any kind of global orbit correction, running independently. It offers significant enhancements over the previous system, including parallelization capabilities and improved efficiency.

Speaker: Hairong Shang (Argonne National Laboratory)

16:00 The control and monitoring system for the APS-U front-end XBPM

The Advanced Photon Source Upgrade (APS-U) project aims to enhance the performance and capabilities of the APS, delivering brighter and more coherent x-ray beams to support cutting-edge scientific research. A critical component of this upgrade is the front-end X-ray Beam Position Monitor (XBPM) system, which plays a vital role in ensuring beam stability and precision. This paper presents the design and implementation of the control and monitoring system for the APS-U front-end XBPM. The system integrates advanced hardware and software solutions to achieve real-time monitoring of x-ray beam position. Key features include high-resolution data acquisition, robust signal processing algorithms, and seamless integration with the APS-U control architecture. The system utilizes the Experimental Physics and Industrial Control System (EPICS) input/output controllers (IOCs) to interface with front-end instruments. By leveraging EPICS IOCs, the system achieves high reliability and flexibility.

Speaker: Shifu Xu (Argonne National Laboratory)

16:00 Tool Chain for Simulations of Bi-Filar Coil Winding for Fast Quench Protection

The advancement of high-field magnets utilizing high-temperature superconductors (HTS) brings about complex challenges, especially in quench detection and protection. Traditional methods often fall short due to the inherently slow quench propagation in HTS materials. One promising approach to overcome this involves using a bifilar winding configuration, where two conductors are placed side by side. Under normal operation, they function in series, but during a quench event, they switch to an anti-parallel mode. This shift reduces the differential inductance of the coil to near zero, enabling rapid current oscillations through a capacitor discharge. The resulting high-frequency current flow leads to swift, uniform heating, triggering a full-coil quench within microseconds. Moreover, the strong mutual coupling between the two windings significantly reduces electrical noise in voltage measurements. In this work, we explore the viability of this concept by designing, constructing, and testing a REBCO bifilar racetrack coil in liquid nitrogen. We also present a validated simulation model that closely mirrors the coil's dynamic behavior under these conditions, aligning well with experimental observations.

Speaker: Rehan Jayathilaka (Northern Illinois University, Fermi National Accelerator Laboratory)

16:00 Towards accurate beam sigma matrix determination in a transport line using differentiable simulation

Precise characterization of the beam distribution is essential for matching the incoming beam and optimizing injection into storage rings. We present a method to efficiently reconstruct the full 5×5 beam sigma matrix (excluding the time coordinates) at the booster-to-storage-ring (BTS) transport line at the Advanced Photon Source Upgrade (APS-U). Earlier works demonstrated that the beam sigma matrix can be accurately reconstructed using linear transport matrices under the assumption of negligible chromatic effects. However, the presence of chromaticity introduced significant non-linearities and leads to discrepancies from the linear approaches.
In this work, we demonstrate a novel approach leveraging Cheetah, a differentiable beam dynamics simulation framework, to enable direct gradient-based optimization of the beam matrix. Initial results shows efficient and accurate reconstruction under both linear and second-order tracking models, providing improved robustness in simulation studies. This method offers a scalable, interpretable, and computationally efficient alternative to black-box methods for beam matrix reconstruction in transport lines in presence of complex effects.

Speaker: Chenran Xu (Argonne National Laboratory)

16:00 Towards real-time calibration of CBPMs using synchronous RF injection

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)

16:00 Transverse phase space tomography at FACET-II

We present recent development of transverse phase space tomographic reconstruction techniques at FACET-II. We present implementation of such techniques in the FACET-II injector, and utilize it to characterize the two-bunch from photocathode configurations. We demonstrate the characterization of two-bunch phase space misalignment and its potential control and application in PWFA experiments. We also characterize the effect of transverse space-charge force by varying two-bunch charge ratio. We also present single-shot and multi-shot tomographic reconstruction of electron spectroscopy image for PWFA-accelerated beam characterization.

Speaker: Yiheng Ye (SLAC National Accelerator Laboratory)

16:00 Two-stage constrained Bayesian optimization for particle accelerator tuning

Particle accelerators are highly complex, non-linear systems that require rapid tuning during operation to meet requirements on beam qualities for applications in different scientific disciplines. Multi-objective Bayesian Optimization (MOBO) has been recently demonstrated at SLAC MeV-UED facility for speeding up online electron beam tunings and obtaining Pareto Fronts giving trade-offs between key beam properties of interest. One challenge in algorithm- based tuning is the alignments of beam through the collimators, screens and timing diagnostics under different system working points. This usually requires trial-and-error based hand tunings and strongly limits the data taking efficiency. Here, we utilize two-stage constrained Bayesian optimizations (CBE-MOBO) for beam tunings at MeV-UED. Instead of directly optimizing objectives of interest, beam property constraints are first modeled in the tuning-measurement joint domain using constrained Bayesian exploration. Based on the information learned, MOBO is then used to efficiently search the parameter space and resulted in dramatically improved valid data efficiency. Our results show potential of CBE-MOBO for autonomous tunings of particle accelerators.

Speaker: Fuhao Ji (SLAC National Accelerator Laboratory)

16:00 Ultra-fast switching utilizing an IVA topology for chopper applications

Recent trends in power electronics indicate increasing demand for fast response switching networks with sub nanosecond switching speed at a variety of volt-ages. Gate driving networks meet the desired switching speeds using COTS (Commercial Off-The Shelf) parts. This work describes an IVA (Inductive Voltage Adder) system capable of switching in the single digits of ns with a projected voltage output of 2 kV, using a gate driving topology to drive GaN (Gallium Nitride) HEMTs (High Electron Mobility Transistor). These rapid switching systems are proposed to be used in the LAMP (LANSCE Accelerator Modernization Project) chopper to effectively produce clean beam to select target stations, producing the needed output.

Speaker: Kyle Hansz (Los Alamos National Laboratory)

16:00 Upgrade to fixed and translating scintillation-based loss detector system in the Fermilab Drift Tube Linac

The closed-off structure of the Fermilab Drift Tube Linac precludes a robust array of instrumentation from directly monitoring the H- beam that is accelerated from 750 keV to 116 MeV. To improve beam tuning and operational assessment of Drift Tube Linac performance, scintillator-based loss monitors were previously installed along the exterior of the first two accelerating cavities to assess low energy beam losses. Here we present a recent upgrade to the loss monitor system, including significant improvements in analog signal processing to address baseline-interfering noise; digitization of the signals to enable regular operational use and tuning; and a new remote operation upgrade of the translating loss monitor with precise positioning of the loss monitor along its nine-foot track. Data from the fixed and translating detectors collected under varying beam conditions validate the utility of the upgrade.

Speaker: Erin Chen (Fermi National Accelerator Laboratory)

16:00 Virtual Critical Coupling Technique for Elimination of Power Reflections in RF Cavities

Effective control of power reflections in high-power RF systems is essential for maintaining energy efficiency and protecting system components. Virtual Critical Coupling (VCC) is a novel approach that allows to eliminate reflections by temporally shaping a complex frequency excitation signal in a resonator to ensure that it fully traps all impinging energy. The absorbed energy is stored in the resonator without being dissipated, and it can be released at will. Unlike traditional coupling techniques, this method does not require mechanical modifications. In this talk, we will present VCC experimental results achieved in an S-band standing wave linear accelerator using a custom low-level RF system and a 5 MW klystron. These findings demonstrate a scalable method for improving the efficiency and stability of high-power resonant systems with potential applications in accelerator technology.

Speaker: Aurora Cecilia Araujo Martinez (RadiaBeam Technologies (United States))

16:00 X-ray inspection for non-invasive real-time beam detection

Conventional methods for measuring lower-energy particle beams (<several MeV), such as Faraday cups, moving wire scanners, and scintillators, are invasive and become impractical for higher-energy beams that exceed material tolerances. Current techniques for detecting beam drift often rely on spill radiation monitoring or beam position devices with off-axis electrodes, which can produce unwanted secondary particles. This study investigates a non-invasive X-ray inspection technique for beam characterization. Through simulations, we examine optimal X-ray energies, detector-beam configurations, scattering mechanisms, and profile reconstruction methods. The results demonstrate the feasibility of real-time beam monitoring without interfering with the primary beam path, offering significant benefits for high-energy physics experiments where maintaining beam integrity is essential.

Speaker: Prabir Roy (Lawrence Livermore National Laboratory)

19:00 → 21:00 Chair's Reception (by Invitation)

Tuesday 12 August

08:00 → 09:00 Coffee

09:00 → 10:30 Tuesday Tutorial

09:00 Generative Deep Learning for Particle Accelerators

Generative deep learning has emerged as a transformational technology for a wide range of tasks including tools such as Stable Diffusion, IMAGEN, DALL-E, and Midjourney for image generation from user-defined captions, AlphaFold for prediction of 3D protein structures directly from amino acid sequences, and large language models such as GPT and Claude which can carry on conversations, summarize documents, and write custom computer code. For particle accelerators, such generative models have amazing potential for various tasks including surrogate models, virtual beam diagnostics, automated adaptive beam tuning and optimization for autonomous accelerator control, and accelerator design. This talk gives an overview of state-of-the art generative AI techniques including transformers, which are the backbone of large language models and are state-of-the-art for learning distant dependencies in long sequences of data, variational autoencoders, and diffusion-based generative models which are the state-of-the-art for creating high resolution representations of complex objects. The tutorial will also discuss how feedback and hard physics constraints can be built into these generative frameworks to make robust tools for complex time-varying dynamic systems. The tutorial will also present examples of how these models are being utilized in science in general and specifically for a wide range of accelerator applications such as generative models for virtual 6D phase space diagnostics.

Speaker: Alexander Scheinker (Los Alamos National Laboratory)

09:00 → 10:30 Photon Sources and Electron Accelerators

09:00 A new multi-pulse kiloampere electron linac for dynamic x-radiography

The Advanced Sources and Detectors (ASD) Scorpius project is a collaboration between Los Alamos National Laboratory, Lawrence Livermore National Laboratory, Sandia National Laboratories, and the Nevada National Security Sites to develop and build a multi-pulse kiloampere-class 22 MeV electron accelerator for dynamic x-radiography for national security. The project has begun fabrication and assembly and is scheduled to become operational in 2028. Notably, ASD Scorpius uses a solid-state pulsed power system to deliver an extremely flexible range of electron – and thus x-ray – pulses. Also, the location of the accelerator in a pre-existing mine deep underground in Nevada imposes significant design constraints. This presentation will describe the design, current status, and plans for ASD Scorpius.

Speaker: Saeed Assadi (Lawrence Livermore National Laboratory, Lawrence Livermore National Security)

09:30 X-ray Cavity Based XFELS

Cavity-based X-ray free-electron lasers present a promising path toward fully coherent, high-brightness X-ray sources with enhanced stability and spectral purity. By using Bragg-reflecting crystal cavities to recirculate and amplify an X-ray seed pulse over multiple passes, CBXFELs offer the potential for orders-of-magnitude improvements in coherence and brightness compared to single-pass FELs. This talk will present an overview of the CBXFEL concept and the proof-of-principle experiment currently under development at SLAC. Recent progress will be presented, along with ongoing efforts in beam–X-ray overlap diagnostics and cavity alignment. The talk will also address the key technical challenges ahead for CBXFELs and briefly explore alternative cavity-based XFEL designs as promising paths forward.

Speaker: Mario Balcazar (SLAC National Accelerator Laboratory)

10:00 Demonstration of a reliable, high gain laser plasma accelerator driven free electron laser at BELLA

Laser plasma accelerators (LPAs) have emerged as a viable alternative to traditional accelerators for various applications, thanks to their capability to generate high-brightness beams and much higher accelerating gradients. This enables more compact designs for future light sources, such as free electron lasers (FELs). FEL technology leveraging LPA sources is progressing swiftly, with several key milestones achieved in recent years. However, significant work remains to be done to move from proof-of-concept experiments to the dependable operation of LPA-driven FELs. Recent initiatives at the BELLA center's Hundred Terawatt Undulator beamline, which includes an electron beam transport section leading to a 4-meter-long, strong focusing undulator, have successfully demonstrated the consistent operation of a high-gain FEL in the SASE regime. SASE gain is detectable on 90% of shots with measured SASE gain in excess of 1000.

Speaker: Samuel Barber (Lawrence Berkeley National Laboratory)

10:30 → 11:00 Coffee

11:00 → 11:30 Hadron Accelerators (Invited)

11:00 Laser Assisted Charge Exchange injection at the Spallation Neutron Source

Laser Assisted Charge Exchange (LACE) technology is being developed to replace foil-based charge exchange injection in high power H- accelerators. The possibility of replacing the foil with field-stripping will greatly reduce injection losses, and therefore is a promising technology for future high-intensity multi-megawatt power H- beams. The technique of LACE has been demonstrated but not in a configuration that allows injection of beam into a ring. This talk will present recent progress on design of a demonstrator at SNS that will allow injection into the SNS ring. The committee also hopes that this talk will review previous experimental results from LACE feasibility studies.

Speaker: Fanglei Lin (Oak Ridge National Laboratory)

11:00 → 11:30 Novel Particle Sources, Acceleration Techniques, and their Applications (Invited)

11:00 Design of Plasma-Based Colliders

This presentation covers the design of plasma and wakefield-based particle colliders. It will briefly review the development of wakefield collider concepts over the past decades and then focus on the HALHF Higgs Factory and 10 TeV pCM Wakefield Collider design studies, discuss commonalities between these efforts and highlight their unique aspects.

Speaker: Jens Osterhoff (Lawrence Berkeley National Laboratory)

11:30 → 12:30 Hadron Accelerators (Contributed)

11:30 SNS Second Target Station proton accelerator shielding design and accident scenario evaluation

Design of the Second Target Station (STS) for Oak Ridge National Laboratory’s (ORNL) world-class Spallation Neutron Source (SNS) Facility is underway. The STS will provide an optimized high-brightness cold neutron source for up to 18 new beamlines, both expanding and complimenting the current neutron science capabilities at ORNL. The Ring to Second Target beam Transport (RTST) will deliver a 700kW beam of 1.3GeV protons at 15Hz to a rotating target composed of individual water-cooled tungsten wedge segments. Spanning roughly 220m, the RTST will consist of 56 quadrupole focusing magnets and 15 dipole bending magnets. Installation and maintenance of large beamline components will be facilitated via a truck access tunnel. While the proton accelerator is in operation, the truck access tunnel entrance is shielded by an arrangement of stacked steel shielding blocks. This shielding design must account for both normal operating conditions as well as design-basis accident scenarios. Provided in this work is an analysis of the accelerator truck access tunnel shielding design for a worst-case full beam loss accident scenario.

Speaker: Wouter de Wet (Oak Ridge National Laboratory)

11:50 Dramatically reducing beam losses at BNL 200 MeV H- linac

The Brookhaven National Laboratory (BNL) 200 MeV drift tube linac (DTL) delivers H- beam at 6.67 Hz and 200 MeV to both the polarized proton program at the Relativistic Heavy Ion Collider (RHIC) and the Brookhaven Linac Isotope Production (BLIP) facility. Through a series of upgrades, particularly in the last two decades, the linac's performance has significantly improved. Reconfigurations of the low-energy and medium-energy beam transport systems have been key contributors to this progress. Key improvement include:
A 50% increase in transmission for high-peak-current isotope production, a 50% reduction in transverse emittance and A dramatic three-order-of-magnitude reduction in beam loss.
These upgrades and has significantly enhanced the overall performance and efficiency of the BNL 200 MeV linac.

Speaker: Deepak Raparia (Brookhaven National Laboratory)

12:10 Simulation modeling of first-turn losses for the LANSCE Proton Storage Ring (PSR)

The LANSCE proton storage ring (PSR) accumulates 795 MeV protons into a short, 290 ns pulse over 625 μs, or about 1745 turns. One of the primary limitations for maximum proton pulse intensity is beam loss between the H$^-$ stripper foil and the first dipole magnet downstream of the foil. One of the major beam losses in this region, referred to as “first-turn losses,” are due to incomplete stripping of the injected H$^-$ beam into H$^+$ during the injection process. First-turn losses not only result in a lower extracted proton pulse intensity but can also result in longer maintenance periods following beam runs due to the activation of PSR components, which require “cooling down” prior to any hands-on maintenance. In this work, a detailed particle-tracking model of the PSR injection system was created using the simulation package General Particle Tracer (GPT) using three C++ custom elements created to simulate foil scattering, foil stripping, and Lorentz stripping. The model was used to study the effect of different stripper foil parameters and different injection offsets on first-turn losses and emittance growth. The simulation model will be described, and the simulation results will be presented at the conference.

Speaker: Joshua Yoskowitz (Los Alamos National Laboratory)

11:30 → 12:30 Novel Particle Sources, Acceleration Techniques, and their Applications (Contributed)

11:30 Flat beam PWFA theory and experiment at AWA

A wakefield experiment at the Argonne Wakefield Accelerator (AWA) facility utilizes flat electron beams with highly asymmetric transverse emittances to drive plasma wakefields in the underdense regime. These beams create elliptical blowout structures, producing asymmetric transverse focusing forces. The experiment utilizes a compact 4-cm-long capillary discharge plasma source developed at UCLA. Analytic models of blowout ellipticity and matching conditions, supported by particle-in-cell simulations, guide the experiment's design. Engineering preparations including the use of windows for vacuum-gas separation, beam transport and diagnostics are discussed along with the first beam runs which involve flat beam generation and transport. The theory of flat beam plasma wakefield interaction will also be discussed

Speaker: Pratik Manwani (University of California, Los Angeles)

11:50 Advanced THz Deflectors for Attosecond MeV-UED Timing

Timestamping electron pulses is a promising strategy for improving the overall temporal resolution of the MeV UED beamline. Timestamping can be achieved with a time-varying deflection of the beam: the deflection angle records the time of arrival of the pulse, from which it is possible to accurately read back the pump-probe delay shot-by-shot. This proposal targets the demonstration of ultrastrong deflection from an optimized, precision machined copper horn structure excited by a tilted pulse front THz source. The tapered horn structure provides an extremely high deflecting field.
We show results of a recent experiment aims to go beyond earlier successful proof-of-concept results by determining optimal design parameters for UED. One important parameter is the diameter of the exit aperture in the horn (through which the electron beam must pass before being collected on the detector). The choice of aperture diameter involves a trade-off between (a) field enhancement from a small aperture diameter, delivering a larger kick for a given THz pulse energy, and (b) higher electron beam transmission from a larger aperture, providing better statistics for measuring the beam centroid and finer substructure.

Speaker: Mohamed Othman (SLAC National Accelerator Laboratory)

12:10 Picometer-scale emittance and space charge effects in nanostructured photocathodes

Generation of ultralow-emittance electron beams with high brightness is critical for several applications such as ultrafast electron diffraction, microscopy, and advanced accelerator techniques. By leveraging the differences in work function and electronic structure between different materials, we enabled spatially localized photoemission, resulting in picometer-scale emittance from a flat photocathode. We also investigated space charge effects by measuring how the emission spot size, as measured in a photoemission electron microscope, changes with the number of electrons emitted per laser pulse. When more than one electron is emitted simultaneously, Coulomb repulsion causes a substantial broadening of the observed source size, enabling us to investigate the limitations imposed by vacuum space charge forces during pulsed photoemission. Our results highlight the potential of nanoscale photoemitters as high-brightness electron sources and offer new insights into electron correlations that emerge after ultrafast photoemission.

Speaker: Anagha Ullattuparambil (Arizona State University)

12:30 → 14:00 Lunch

14:00 → 14:30 Accelerator Technology and Sustainability (Invited)

14:00 High-Power Targetry R&D road map for HEP

Designing a reliable target is already a challenge for MW-class facilities today and has led several major accelerator facilities to operate at lower power due to target concerns. With present plans to increase beam power for next-generation accelerator facilities in the next decade, timely R&D in support of robust high-power targets is critical to secure the full physics benefits of ambitious accelerator power upgrades. The next generation of high-power targets and beam-intercepting devices (beam dumps, absorbers, collimators…) will have more complex geometries, novel materials, and new concepts that allow for use of improved high-heat-flux cooling methods. Advanced numerical simulations need to be developed to support design of reliable high-power beam targets. In parallel, development of radiation-hardened beam instrumentation is needed. Irradiation methods for high-power targets must be further developed, and new irradiation facilities are needed since only a few facilities worldwide offer beams suitable for target testing. A comprehensive R&D program must be implemented to address the many complex challenges faced by multi-MW beam intercepting devices.

Speaker: Sudeshna Ganguly (Fermi National Accelerator Laboratory)

14:00 → 14:30 Beam Instrumentation, Controls, AI/ML, and Operational Aspects (Invited)

14:00 High-dimensional maximum-entropy phase space tomography

Inferring 4D or 6D phase space distributions from 1D or 2D measurements is a challenging inverse problem encountered in particle accelerators. Entropy maximization (ME) is an established method to incorporate prior information in under-constrained problems but is typically infeasible in high-dimensional spaces. In this talk, I discuss two approaches to high-dimensional ME. The first approach extends the Generative Phase Space Reconstruction (GPSR) algorithm, utilizing a class of generative models called normalizing flows which provide stochastic differentiable entropy estimates. The second approach modifies the classic MENT algorithm, using the method of Lagrange multipliers and Markov Chain Monte Carlo (MCMC) sampling to solve the constrained optimization. After reviewing the theory behind these approaches, I describe numerical tests of their convergence and accuracy, followed by applications to experimental data. I conclude by mentioning possible routes to uncertainty quantification within the ME framework.

Speaker: Austin Hoover (Oak Ridge National Laboratory)

14:30 → 15:30 Accelerator Technology and Sustainability (Contributed)

14:30 Traveling Wave excitation results in SRF Cavity With a Feedback Waveguide at 2K.

Conventional SRF cavities are used in standing wave regime and are limited by surface fields to ~50 MV/m. In order to overcome this limit, Superconducting Traveling Wave (SCTW) cavity was proposed as it allows to achieve ~1.5 times higher accelerating gradient operating at lower phase advance per cell, thus improving transit time factor. However, power recirculation through a feedback waveguide is required to maintain cavity efficiency. Funded by the U.S. Department of Energy's SBIR program, Euclid Techalbs, in collaboration with Fermilab, demonstrated in the past the surface processing capability of a single-cell prototype with a feedback waveguide. Subsequently, a 3-cell prototype was designed and fabricated to demonstrate a traveling wave regime in SRF cavity with a feedback waveguide at cryogenic temperatures and the highest gradients. Previously, we have demonstrated the feasibility of traveling wave excitation and control at 2K in the cavity with highly loaded QL=1e6, which is typical for high current machines. Here we present our recent results of traveling wave control with a more challenging smaller bandwidth.

Speaker: Chunguang Jing (Euclid Techlabs (United States))

14:50 Tuning-Free High-Gradient RF Structures: From SwissFEL to FCC-ee – A Scalable Technology for Future Accelerators

At the Paul Scherrer Institute (PSI), a novel, industrially scalable, and tuning-free manufacturing process for normal-conducting high-gradient C-band accelerating structures has been developed and successfully implemented for the Swiss Free-Electron Laser (SwissFEL). This approach, which eliminates RF post-production tuning, achieves excellent field flatness and phase accuracy through ultra-precision machining and brazing techniques. Over 100 accelerating structures were produced and installed without tuning, operating reliably with breakdown rates below 1e-9 bpp/m. Following SwissFEL’s commissioning and successful operation, PSI extended this process to other frequency bands, including S-band and X-band, for applications in collaborations with CERN, ELETTRA, and DESY. These efforts include the construction of X-band accelerating structures for CLIC, high-gradient S-band structures for the FERMI FEL upgrade, and the development of ultra-precise transverse deflecting structures (TDS) with variable polarization for advanced beam diagnostics. Building on this expertise, PSI is now leading a multi-institutional effort to develop the lepton injector for the FCC-ee, with plans for mass production of over 400 tuning-free RF structures. This contribution presents the evolution, deployment, and future prospects of tuning-free RF structure technology, underscoring its pivotal role in the next generation of accelerator infrastructures.

Speaker: Paolo Craievich (Paul Scherrer Institute)

15:10 Operation and R&D of liquid lithium charge stripper at FRIB

Charge stripping is an essential technique for the efficient acceleration of heavy ions. The Facility for Rare Isotope Beams (FRIB) utilizes the Liquid Lithium Charge Stripper (LLCS) to produce the world’s most powerful heavy ion beams, so far demonstrated up to 20 kW with 200 MeV/u energy. In the FRIB driver linac, electrons are stripped by a thin film jet of liquid lithium flowing at 50 m/s. The LLCS has been in operation with FRIB’s linac since 2022 and will support the future ramp-up of the beam power to 400 kW. Our operation experiences have revealed that the performance of the LLCS will be further improved by increasing the film thickness twice and enhancing the uniformity and stability of the film. In this presentation, we report on the operational experiences with the current LLCS and various R&D activities for its future upgrade.

Speaker: Ryoto Iwai (Facility for Rare Isotope Beams)

14:30 → 15:30 Beam Instrumentation, Controls, AI/ML, and Operational Aspects (Contributed)

14:30 Experience Integrating Online Modeling / Adaptive Digital Twin Infrastructure and ML-based Tuning for Accelerator Control at SLAC

SLAC and collaborators are developing infrastructure and algorithms for deploying online physics models and combining them with machine learning (ML) models and ML-based feedback from its running accelerators. These models predict details of the beam phase space distribution, include nonlinear collective effects, and leverage high performance computing and ML-based acceleration of simulations to enable execution in reasonable times for control room use. By enabling accelerator system models to be adapted over time and increasing the speed of model execution, these system models can provide useful information for both human-driven and automated tuning. System models such as these are sometimes called "digital twins", which are distinguished from offline models by the bi-directional flow of information with the real system. We have also been leveraging these system models to speed up accelerator tuning, by providing initial guesses of settings (i.e. "warm starts") and physics information to speed up ML-based tuning. For example, we have used these models to provide priors for Bayesian optimization and training platforms for reinforcement learning. Here, we give and overview of these developments (both research and infrastructure), our deployment experience, and applications at LCLS, LCLS-II, and FACET-II, with a focus on emittance tuning, FEL pulse intensity tuning, and phase space shaping. We also discuss ongoing collaborations with LBNL, JLAB, FNAL, and BNL in this space.

Speaker: Auralee Edelen (SLAC National Accelerator Laboratory)

14:50 Electro-optic sampling beam positioning monitor for relativistic electron beams

Non-destructive diagnostics able to resolve transverse offsets and longitudinal separation of ultra-relativistic, two-bunch electron beams are necessary for a variety of applications including the ion channel laser (ICL) and other plasma wakefield (PWFA) experiments. A prototype electro-optic beam positioning monitor (EOS-BPM) utilizing two independent laser pulses traveling through a pair of EO crystals has been installed at the SLAC National Accelerator Laboratory FACET-II facility. This system is capable of order 10 fs temporal resolution and order 100 µm transverse position resolution. To achieve better transverse resolution we introduce a new design using an axicon lens to create a donut beam and a multi-crystal structure placed around the axis of propagation of the electron beam. Experimental results of the prototype EOS-BPM along with the simulated response of the new EOS-BPM design to the ultra-relativistic, two-bunch electron beam used for PWFA experiments at FACET-II will be presented.

Speaker: Elena Ros (University of Colorado Boulder)

15:10 SRF cavity instability detection with machine learning at CEBAF

During the operation of the Continuous Electron Beam Accelerator Facility (CEBAF), one or more unstable superconducting radio-frequency (SRF) cavities often cause beam loss trips while the unstable cavities themselves do not necessarily trip off. The present RF controls for the legacy cavities report at only 1 Hz, which is too slow to detectfast transient instabilities during these trip events. These challenges make the identification of an unstable cavity out of the hundreds installed at CEBAF a difficult and time-consuming task. To tackle these issues, a fast data acquisition system (DAQ) for the legacy SRF cavities has been developed, which records the sample at 5 kHz. An unsupervised learning framework has been developed to identify anomalous SRF cavity behavior. We will discuss the present status of the DAQ system and our framework, along with recent successes in detecting anomalous cavity behavior. Overall, our method offers a practical solution for identifying unstable SRF cavities, contributing to increased beam availability and machine reliability.

Speaker: Dennis Turner (Thomas Jefferson National Accelerator Facility)

15:30 → 16:00 Coffee

16:00 → 16:30 Exhibitor Presentations: Parallel #1

16:00 BeamNetUS (Navid Vafaei-Najafabadi)
16:05 Stangenes (Chris Yeckel)
16:10 RadiaSoft (David Bruhwiler)
16:15 JEMA (Claude Troesch)
16:20 BEXT (Dennis Pieri)
16:25 BRANDTECH Scientific (Peter Beck)

16:00 → 17:30 GARD RF Program coordination

16:00 → 18:00 Tuesday Poster Session

16:00 2D phase space tomography with SciBmad tracking

This paper presents the application of BeamTracking.jl, a key package in the Julia based SciBmad software ecosystem for differentiable accelerator physics simulations. This study demonstrates the use of phase space tomography to reconstruct the 2D phase space distribution of a particle beam. Using the SciBmad tracking package BeamTracking.jl, the phase space distribution of the beam can be constructed from the beam’s projections after being transported through a quadrupole and a drift. This result showcases the utility of SciBmad and highlights its potential for studying and optimizing injection, transport, and beam acceleration.

Speaker: Xinyi Yang (Cornell University (CLASSE))

16:00 A beam chopping scheme concept for the new LAMP MEBT

As part of the LANSCE Accelerator Modernization Project (LAMP), the two existing 750-keV Cockcroft Waltons are planned to be replaced by a single radio-frequency quadrupole (RFQ). The new LAMP front-end needs to deliver beams with similar timing patterns to what is currently delivered to the multiple target stations. To accomplish this, the 3-MeV Medium Energy Beam Transport (MEBT) is designed with two choppers that help produce beam timing patterns required by the experimental user facilities. The new RFQ will introduce satellite bunches around the single high-intensity bunch that is required by the users. These satellite bunches need to be removed in the MEBT. This contribution describes the design of LAMP MEBT with a beam chopping scheme and presents simulation results.

Speaker: Dr Salvador Sosa Guitron (Los Alamos National Laboratory)

16:00 A community effort toward a Particle Accelerator Lattice Standard (PALS)

A major obstacle to collaboration on accelerator projects has been the sharing of lattice description files among modeling codes. To address this problem, a standardized lattice description called the Particle Accelerator Lattice Standard (PALS) is being developed. PALS development is a community-wide international effort involving accelerator physicists from multiple institutions. Along with the standard, interface packages written in commonly used languages will be developed.

The importance for developing PALS is due to the increase in scale and complexity of new machines bringing an ever greater need for global collaboration, as well as interfacing with the data-driven activities using artificial intelligence and machine learning.

The proposed Particle Accelerator Lattice Standard aims to promote: (i) portability between applications, (ii) a unified open-access description for scientific data (publishing and archiving), (iii) a unified description for post-processing, visualization and analysis. We will present an introduction to the effort, an overview of the standard, examples of applications, and discuss plans and future involvements from the community.

Speaker: Chad Mitchell (Lawrence Berkeley National Laboratory)

16:00 A GPU-parallelized Weak-Strong Beam-Beam Simulation Code in Julia Programming Language

As the scale of the EIC project continues to grow, beam-beam simulations incorporating increasingly realistic models are becoming essential. Consequently, a high-performance and extensible simulation code is indispensable. In this contribution, we report on our progress in developing a GPU-parallelized weak-strong beam-beam tracking code in the Julia programming language.

Speaker: Yi-Kai Kan (Brookhaven National Laboratory)

16:00 A higher momentum aperture lattice proposed for the sPHENIX background problem

During the 2024 Au+Au 100 GeV physics run, the sPHENIX MVTX detector experienced background issues originating from the Yellow beam, leading to frequent auto-recoveries during streaming mode operation. One hypothesis attributes the background to the loss of off-momentum particles. An evaluation of the momentum apertures in both RHIC rings revealed that the Yellow ring had a worse momentum acceptance compared to the Blue ring. To address this, a new lattice design with a reduced W-function was proposed. This report presents the momentum aperture comparison between the two rings, the proposed new lattice design considering additional constraints, and the resulting momentum and dynamic apertures.

Speaker: Yun Luo (Brookhaven National Laboratory)

16:00 A multi-harmonic cavity system for bunch lengthening for the NSLS-II upgrade

We discuss a bunch lengthening scheme based on the combination of Higher Harmonic Cavities (HHCs) of different order, aimed to provide a higher bunch lengthening factor then HHC systems of the same order. The stability and performance of the HHCs scheme is studied numerically with parameters of the NSLS-II upgrade.

Speaker: Gabriele Bassi (Brookhaven National Laboratory)

16:00 A Self-Consistent Simulation Study of Halo Formation in the PIP-II Linac Driven by Nonlinear Space Charge and RF Field Effects

We present a study of halo formation mechanisms in the high-power PIP-II SRF linac, combining analytical modeling with self-consistent 3D Particle-In-Cell (PIC) simulations. Focusing on the low-energy front-end and transitions between SRF cavity families, we use PIC simulations with realistic 3D field maps to analyze the evolution of the beam distribution. Our results demonstrate that nonlinear space-charge forces, particularly in the presence of initial beam mismatch and non-axisymmetric RF field components, are the dominant drivers of halo development. We show that the halo structure predicted by our simulations deviates significantly from the predictions of simplified particle-core models. Our analytical work, supported by the simulations, identifies the complex resonant interactions responsible for transporting particles to large amplitudes, which are not captured by standard treatments. These findings are crucial for accurately defining the machine aperture and informing the beam loss budget for the machine protection system and devising techniques to avoid beam loss during commissioning and operation.

Speaker: Abhishek Pathak (Fermi National Accelerator Laboratory)

16:00 Accelerator physics requirements and challenges of RF based electron cooler for EIC injection energy

Cooling of hadrons in Electron Ion Collider (EIC) at the injection energy is critical to achieving EIC design parameters. A 13 MeV electron cooler fit for the task is presently under design.
This cooler will use RF-accelerated electron bunches and will provide strong cooling of the hadrons having energy of 24 GeV/nucleon. The paper describes optimization of the cooling performance, taking into account space charge, IBS and other effects, and provides physics requirements for the cooler.

Speaker: Alexei Fedotov (Brookhaven National Laboratory)

16:00 An extended Froissart-Stora formula for changing crossing speed

When the closed-orbit spin tune is ramped linearly through an isolated spin-orbit resonance, the asymptotic polarization loss is well-approximated by the Froissart-Stora formula. However, it is often observed in accelerator simulations that the crossing speed, defined as the slope of the amplitude-dependent spin tune with respect to the machine azimuth, changes at the moment of resonance crossing. For example, the behavior of the amplitude-dependent spin tune in the vicinity of a higher-order spin-orbit resonance can often be reasonably approximated by such a piecewise-linear function. In this paper, we derive an extension to the Froissart-Stora formula which describes the asymptotic polarization loss in the case of changing crossing speed. We then demonstrate that this formula provides a good estimate of the polarization lost when crossing a higher-order spin-orbit resonance in both a toy model and simulations of RHIC.

Speaker: Eiad Hamwi (Cornell University)

16:00 Analysis of the elliptic integrable non-linear system in IOTA using tracking of a single electron

Integrable nonlinear lattices that can be realized in practical accelerators are of great interest, as they offer the potential to support high-intensity beams via Landau damping of collective instabilities. One such system, based on an elliptic potential, has been extensively studied at the IOTA storage ring at Fermilab. The analysis of strongly nonlinear dynamics with multi-particle bunches is challenging due to the rapid decoherence of kicked beams. IOTA has the capability to track single electrons using linear multi-anode photomultiplier tubes for simultaneously measuring transverse coordinates and arrival times of synchrotron-radiation pulses. This technology enables the full reconstruction of turn-by-turn positions and momenta in all three planes for a single particle. Using this apparatus, we measured the dependence of small-amplitude tunes on the strength of the nonlinear magnet, as well as tunes dependence on oscillations amplitudes.

Speaker: Aleksandr Romanov (Fermi National Accelerator Laboratory)

16:00 Aspects of stroboscopic averaging for the invariant spin field

A new method is formulated for calculating the invariant spin field (ISF) at a phase space point by leveraging the property that spins which are distributed along the ISF achieve maximum time-averaged polarization. To quantify this, we construct the time-average of spin rotation matrices beginning at a certain phase space point. It is recognized that the ISF vector at that point achieves the matrix-norm, meaning that the ISF corresponds to the first right-singular vector of that matrix. We show the relation of this method with traditional stroboscopic averaging, such that these methods are two sides of the same coin. This approach offers a new perspective in invariant spin field calculations.

Speaker: Eiad Hamwi (Cornell University)

16:00 Beam halo formation with different cathode distributions

Beam halo refers to the low-density distribution of particles extending beyond the beam core, and its generation and mitigation are important topics in particle accelerator design. Effective mitigation of beam halo is essential for the cooler design based on Energy Recovery Linac (ERL), which must deliver an electron beam with average beam current of 100 mA and a charge 1 nC per bunch. In the ERL injector and booster linacs, space charge effects are stronger due to relatively low beam energy (6 MeV). Additionally, the longer bunch length of approximately 100 ps in this regime vs the RF period of 5.08 ns makes the formation of beam halos more likely. Therefore, effective collimation of beam halo is critical to maintaining the required beam parameters. To design an effective collimation scheme, several halo distributions were generated at the cathode and used to study halo formation within the injector-merger. This paper presents different halo distributions and halo formation, providing insights on halo collimation strategy.

Speaker: Isurumali Neththikumara (Thomas Jefferson National Accelerator Facility)

16:00 Beam tilt characterization using passive streaking structures

Passive wakefield devices such as corrugated structures have demontrated great potential for longitudinal phase space control and diagnostics in FEL. In this paper, we will discuss the application of corrugated structures in beam tilt characterization. We show that a tilted beam experience asymmetric kicks when passing through corrugated metal jaws and the asymmetry of streaked profiles are related to the degree of tilt. Practical implementation of beam tilt correction will be discussed.

Speaker: Tianzhe Xu (SLAC National Accelerator Laboratory)

16:00 Beam-based measurement of LCLS-II injector solenoid misalignments

Solenoid focusing is commonly used in accelerators for electron-beam containment and to compensate for space-charge induced emittance growth at low beam energies. However, misalignment between the solenoid field and the beam trajectory can result in degraded emittance compensation due to orbit kicks, dispersive effects, and non-linearities in the magnetic field profile. This paper presents a technique for beam-based measurement of solenoid misalignments, using expressions derived from a hard-edged solenoid linear transfer matrix with known beam parameters. The results of measurements conducted at the LCLS-II injector are presented as a validation of this method, along with simulation studies that estimate the impact of solenoid misalignments on emittance growth.

Speaker: Ahmed Osman (SLAC National Accelerator Laboratory)

16:00 Beam-Beam Fields with Full Six-Dimensional Coupling: Theory and Computational Methods

This work presents a generalized theoretical framework for calculating beam-beam fields induced by a Gaussian beam with full six-dimensional coupling. We also develop computational techniques for evaluating these fields. A case study based on the Electron-Ion Collider (EIC) electron storage ring illustrates the practical application of the framework. Our results suggest that the standard slice model for the beam-beam kick may significantly underestimate the longitudinal field. The proposed theory may provide a foundation for developing improved simulation models and guiding future design studies.

Speaker: Yi-Kai Kan (Brookhaven National Laboratory)

16:00 Beam-beam limitation toward 10^34 cm^−2 s^−1 luminosity for Electron-Ion Collider

Achieving the design luminosity of in the Electron-Ion Collider (EIC) requires a deep understanding of beam-beam interaction limits in a weak-strong collision regime with flat hadron beams. This contribution presents recent studies of synchro-betatron resonances --- particularly the coupling resonance $2\nu_x-2\nu_y+p\nu_z=0$ --- that can induce emittance transfer between the horizontal and vertical planes and limit luminosity performance. We identify the hourglass effect, caused by the proton bunch length being comparable to the vertical beta functions of both beams at the interaction point (IP), as the dominant source driving this resonance. We further investigate how physical noise, such as intra-beam scattering and fluctuations in the electron orbit and beam size, couples with the beam-beam interaction to amplify emittance growth and reduce luminosity. Mitigation strategies are also discussed. These studies provide important guidance for future EIC operation and inform strategies for potential upgrades.

Speaker: Derong Xu (Brookhaven National Laboratory)

16:00 BeamNetUS Pilot Year Report: Enabling access to beam test facilities

BeamNetUS is a network of facilities united in a common mission to advance accelerator research and applications of accelerator technology through improving awareness and access to these unique facilities. For its pilot campaign, the network includes facilities at Argonne National Laboratory, Brookhaven National Laboratory, Fermi National Accelerator Laboratory, Lawrence Berkeley National Laboratory, SLAC National Accelerator Laboratory, and Thomas Jefferson National Accelerator Facility. These facilities provide complementary capabilities enabling research in plasma physics, beam physics, material science, radiofrequency sources and structures, nuclear physics and electron beam irradiation. In 2025, BeamNetUS awarded time at the facilities through a competitive review process with a remit towards creating new, productive engagements. User awards were given to universities, industry and other laboratories. At NAPAC25 in a satellite meeting, we reflect on the BeamNetUS experience in its pilot year and plans for the future.

Speaker: Emma Snively (SLAC National Accelerator Laboratory)

16:00 Capture efficiency optimization in a compact distributed drive linac

The continuing development of radio-frequency (RF) amplifier technology has paved the way for RF electron accelerators in which each cavity is independently powered, allowing the amplitude and phases to be individually tunable. In this work we study the potential benefits provided by this flexibility in maximizing the capture efficiency in a ≈2 MeV compact accelerator suitable for a wide variety of industrial and medical applications, as well as traditional roles in research and education. Simulations demonstrate capture efficiencies > 90%, far surpassing typical capture efficiencies which are on the 50% scale.

Speaker: Michael Kaemingk (Los Alamos National Laboratory)

16:00 Commissioning of a fusion collider for interstellar propulsion

A prototype colliding beam accelerator has been fabricated for the study of a fusion-based propulsion concept for interplanetary exploration. The purpose of this prototype is to demonstrate collider luminosities commensurate with the requirements of this application. Direct emission of fusion daughters generates the exhaust velocities required for spacecraft speeds in excess of 1% of the speed of light. Past attempts at nuclear fusion energy production with colliding beams have been limited by Coulomb scattering, a deficiency overcome in this collider architecture. Instead of using fusion fuels such as p/Li7 and He3/He3 capable of generating the required thrust characteristics, this prototype employs deuterons. DD fusion produces neutrons that provide a convenient luminosity detection channel. The commissioning campaign described in this paper operates the collider at a peak beam kinetic energy of 60 keV at the interaction point. Axial confinement and radial focusing are achieved electrostatically. Measured data and subsequent analysis in regard to longitudinal and transverse beam dynamics and beam lifetime are presented.

Speaker: Gerald Jackson (Hbar Technologies, LLC)

16:00 Conceptual design of the Electron-Ion Collider (EIC) Electron Storage Ring (ESR) beam abort systems

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 Construction of approximate invariants for non-integrable Hamiltonian systems

We present a method to construct high-order polynomial approximate invariants (AI) for non-integrable Hamiltonian dynamical systems, and apply it to a modern ring-based particle accelerator. Taking advantage of a special property of one-turn transformation maps in the form of a square matrix, AIs can be constructed order-by-order iteratively. Evaluating AI with simulation data, we observe that AI's fluctuation is actually a measure of chaos. Through minimizing the fluctuations, the stable region of long-term motions, i.e., the dynamic aperture of the accelerator, could be enlarged.

Speaker: Yongjun Li (Brookhaven National Laboratory)

16:00 CST simulation and RF power for an equivalent SCL cavity at LANSCE

Superconducting LINAC (SCL) technology has been a mature option for several years. The SCL option has been studied in the past. This option has the potential to improve beam availability to the LANSCE facility users by allowing the RF system to partially migrate to a modern RF power solution such as the Spallation Neutron Source (SNS) or the European Spallation Source (ESS) klystron modulators. Due to the higher RF efficiency of the SC cavity, the use of recent advances in Solid-State Power Amplifiers (SSPA) becomes a possibility as an adequate substitute for the RF power plant. Another important aspect of the SCL option is that the partial removal of the Coupled Cavity LINAC (CCL) at β=0.78 and implementing high-gradient SC cavities provides a technically sound solution to reach beam energy of more than 1 GeV within the already existing beam tunnel, making this available for the users at LANSCE. In addition, the current capability of 800 MeV beam can be maintained by choosing a dynamic mode of operation where only the needed SC RF structures are operated. This would allow continued use of the Proton Storage Ring (PSR) without requiring an upgrade, while providing the >1 GeV option for other users on demand.

Speaker: Jesus Valladares (Los Alamos National Laboratory)

16:00 Current status of the electron transport line from RCS to ESR: RTE line

The electron injection system of the U.S. Electron-Ion Collider (EIC) is located outside of the RHIC tunnel. Electrons beams accelerated by the Rapid Cycling Synchrotron (RCS) must be transported to the Electron Storage Ring (ESR), which resides within the RHIC tunnel. To accomplish this, a dedicated beam transport line, referred to as RTE (RCS-to-ESR) line is being designed. The proposed conceptual design comprises three main sections; RCS extraction, a vertical bend and dispersion suppression region, and ESR injection matching. The extraction section uses pulsed kickers and septum magnets to achieve a total deflection angle of 3 degrees. To align the injection section with ESR, the beamline must provide a vertical elevation of 1.68 m, and an array of FODO cells is used to suppress the vertical dispersion. The total length of the RTE line is approximately 133 m, and this paper presents the current design status and considerations for this transport line.

Speaker: Isurumali Neththikumara (Thomas Jefferson National Accelerator Facility)

16:00 Density functional theory approach for calculating electronic band structure parameters for monte carlo simulations of photoemission

Monte Carlo simulations are a powerful tool for modeling photoemission from photocathodes, enabling the prediction of key parameters such as quantum efficiency, mean transverse energy, electron spin polarization, and photocathode response time. However, these simulations require material band structure parameters, which are not always available from experiments. This work aims to establish a reliable framework for calculating electronic band structure parameters using Density Functional Theory (DFT). Specifically, we apply this framework to investigate the effects of lattice strain and temperature on the electronic band structure and electron transport in GaAs. This approach will be further extended to explore band structure modifications in heavily p-doped semiconductors and to calculate electronic band structures of novel spin-polarized photocathode materials.

Speaker: Joniel Mendez (Northern Illinois University)

16:00 Derivation of the conditions under which Boussard's criterion for the microwave instability may apply

The microwave instability is typically driven by perturbations whose characteristic wavelength is much shorter than the bunch. In this case, Boussard argued that the microwave instability threshold can be found using the predictions of an infinite (coasting) beam, with the average current replaced by the peak current*. We revisit this problem, and theoretically show that if the variation of the synchrotron tune with energy can be neglected then Boussard's hypothesis holds provided 1) the longitudinal ring impedance is dominated by frequencies much shorter that the inverse bunch length; 2) the single-particle wakefield is much shorter than the bunch length, or, equivalently, the impedance is slowly varying over frequencies longer than the inverse bunch length; 3) the resulting instability has a sudden onset with growth rate of the order of the synchrotron frequency. The first two conditions imply that perturbations are localized within distances much less than the bunch length, while the last condition means that the instability experiences significant growth before the particles can make one synchrotron oscillation. While these conditions may be ``obvious'' in retrospect, we believe that the last two have not been clearly stated or widely appreciated.

Speaker: Ryan Lindberg (Argonne National Laboratory)

16:00 Design of flat-to-round (Vortex) beam adapter with strong space charge

We describe the design of a symmetrical skew-quadrupole triplet and associated four-quadrupole matching section for a flat-to-vortex beam transformation in a low-energy, high current electron experiment at the University of Maryland. We review the basic principles involved, from the Courant-Snyder parameters, beam (sigma) matrix, conservation of canonical angular momentum and emittances, to the evolution of the beam envelopes, with emphasis on practical aspects of the design. The initial optimization involves the use of a standard sigma matrix code that includes direct space charge effects. Refinement of the calculations are made possible by a set of moment equations that can use rotated quadrupoles and an expanded set of parameters for optimization. Additional particle-in-cell (PIC) computer simulations and preliminary results from experiments are presented in an accompanying paper.

Speaker: Brian Beaudoin (University of Maryland, College Park)

16:00 Design update on the transition beamline for the CEBAF Energy Upgrade

For Jefferson Lab’s 22GeV upgrade, two new permanent-magnet Fixed-Field Alternating Gradient (FFA) arcs will be integrated to serve the accelerator’s six highest-energy recirculation passes. Connecting these FFA arcs to the existing linear accelerator (linac) requires a carefully engineered transition section. The current design has two parts where the first part adiabatically matches the beam dispersion and orbit trajectories, while the second part aligns the Twiss parameters (alpha and beta functions) with those at the linac entrance. Given the tight spatial constraints and multiple matching requirements, a genetic algorithm is being explored to optimize the beam optics matching. This paper presents the current progress in developing and optimizing this transition.

Speaker: Bamunuvita Gamage (Thomas Jefferson National Accelerator Facility)

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: Ningdong Wang (Cornell University)

16:00 Dynamic aperture studies at the Fermilab recycler ring

As part of the Proton Improvement Plan II (PIP-II), Fermilab aims to increase beam intensity delivered to neutrino experiments. In this context, higher intensity injection into the Recycler Ring enhances space charge effects, pushing operations closer to third-order resonances. These resonances reduce the Dynamic Aperture (DA), leading to increased beam loss. This study presents simulations of DA as a function of tune in the Recycler Ring, incorporating chaos indicators such as the Reversibility Error Method (REM) and Frequency Map Analysis (FMA). The effectiveness of existing resonance mitigation strategies is evaluated by quantifying their ability to delay DA degradation. Additionally, the study examines how space charge detuning and DA limitations dictate viable operational tune points for the Recycler Ring.

Speaker: Cristhian Gonzalez-Ortiz (Fermi National Accelerator Laboratory)

16:00 Efficient phase space density construction via transfer operators

Optimizing accelerator lattices requires evaluating phase space densities through extended or repeated particle-in-cell simulations. These are computationally expensive due to the need to solve the equations of motion for large numbers of charged particles in prescribed and self-consistent fields. We introduce a method that significantly reduces the computational burden by constructing approximate invariant densities via a two-step transfer operator approach. The method gives practical approximations to phase-space level curves, capturing essential dynamics without extensive particle pushing. Prior work has shown how to find such curves via kernel-based level set learning. Our method is fast, avoids kernel tuning, and integrates with existing codes, enabling rapid assessment of figures of merit in constrained optimization algorithms such as Adjoint with a Chaser, AWC*. AWC efficiently computes gradients with respect to lattice parameters while preserving moment periodicity and accounting for self-fields and collective effects. We present results demonstrating accuracy, speed-up, and trade-offs between precision and computational cost in lattice design.

Speaker: Vincent Tembo (University of Maryland, College Park)

16:00 Electro-mechanical oscillations and instabilities in PIP-II SSR2 and LB650 cavities.

Instabilities in room temperature accelerator RF cavities due to interaction between electromagnetic RF field and mechanical vibrational modes of the cavity has been observed in 1960s [1,2]. In superconducting RF (SRF) cavities these types of instabilities may be even stronger because of larger beam loading factor (Q_L), large cavity field, and stronger effects of cavity de-tuning due to ponderomotive forces (so-called Lorentz force de-tuning, LFD). In this paper we present observation of electro-mechanical oscillations (EMO) and instabilities in PIP-II SSR2 and LB650 cavities. Analytical and computational models of EMO are discussed, and stability criteria are defined.

Speaker: Alexander Sukhanov (Fermi National Accelerator Laboratory)

16:00 Electromagnetic space-charge fields in a cylindrical cavity with a small aperture: analytical and numerical analysis

We present an analytical and numerical study of the electromagnetic space-charge fields generated by a relativistic charged particle beam propagating inside a cylindrical conducting cavity with a small aperture at one end. The system models a practical RF photoinjector geometry where the beam originates from a flat cathode and accelerates longitudinally through the cavity. By employing a Green’s function method and the small-hole approximation, we derive closed-form expressions for the scalar and vector potentials and their associated electric and magnetic fields. The analytical solution accounts for both unperturbed cavity modes and perturbative effects due to radiation leakage through the aperture, modeled via a magnetic dipole moment. We further validate our results using a vectorized and parallelized numerical integration scheme in normalized coordinates. The resulting field profiles reveal the spatial structure and temporal evolution of the longitudinal and radial fields, showing excellent agreement with expected physical behavior. These results are crucial for understanding beam–field interactions in high-brightness electron sources and have implications for the design of high-gradient and high-power RF accelerators and vacuum electronic devices.

Speaker: Chong Shik Park (Korea University Sejong Campus)

16:00 Electron beam current spike formation for short pulse generation with two lasers

Formation of current spike in electron bunch has direct implication for attosecond pulse generation in XFEL. In this paper, we present start-to-end simulation for tunable, short current spike generation in the LCLS copper linac using photocathode laser shaping. Our approach uses two stacked laser pulses—a long and a short pulse—to imprint a small modulation in the electron bunch as it is created in the injector. This initial modulation is then amplified as the bunch travels through the downstream bunch compressors, ultimately forming a sharp current spike. We also discuss how different shapes of the initial laser pulses influence the final current profile and the efficiency of spike generation.

Speaker: Tianzhe Xu (SLAC National Accelerator Laboratory)

16:00 Emittance mismatching of electron injection for the Electron Storage Ring of the Electron-Ion Collider

The Electron-Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized high-energy electron beams with polarized proton and ion beams, achieving luminosities of up to 1 × 10^34 cm^−2 s^−1 in the center-of-mass energy range of 20-140 GeV. The EIC consists of two storage rings: the Hadron Storage Ring (HSR) and the Electron Storage Ring (ESR). Given the short polarization lifetime of the electrons, a swap-out injection scheme is adopted for the ESR injection. In this article, we estimate the injection mismatch tolerances for the electron swap-out injection from the Rapid Cycling Synchrotron to the ESR. In these studies, strong-strong beam-beam simulations are performed. The tolerances for injection emittance mismatch in the ESR are presented in this article.

Speaker: Yun Luo (Brookhaven National Laboratory)

16:00 Enhancing Reciprocal Space Resolution in MeV Ultrafast Electron Diffraction with Permanent Magnet Lenses

Ultrafast electron diffraction (UED) probes structural dynamics on femtosecond timescales and angstrom spatial scales. Artificial crystals are a novel experimental target for UED beams. Typically composed of lattice-mismatched atomic layers, the repeating atomic patterns in artificial crystals can have periods several nanometers in length, which produces intricate satellite features in the electron diffraction pattern. Resolving fascinating satellite diffraction peaks in a compact UED beamline requires high angular magnification. In this work, we describe the implementation of post-sample angular magnification using a pair of compact permanent magnet solenoid lenses. Configured as an objective-eyepiece pair, these lenses achieve a camera length of 50 meters, i.e., the lens system is equivalent to extending the beamline drift length by a factor 15. We demonstrate the advantages of this scheme with data that resolves satellite diffraction peaks in a heterostructure sample.

Speaker: Cameron Duncan (Cornell University (CLASSE))

16:00 Estimation of the wakefield resonant frequency using different simulation tools

Reliable and fast wakefield calculations are important for beam dynamics and THz generation in accelerators. We compare approaches and limitations with different available simulation tools and compare results. As an example, we analyze a cylindrical corrugated waveguide with narrower and wider radii of 5 and 6 mm, and aperture width and periodicity of 1 and 2 mm using ABCI by KEK and ANSYS HFSS simulation software. First, ABCI was used to determine the resonant frequency of the cylindrical corrugated waveguide with different lengths. The corresponding results were taken as a reference to examine the simulation method in the ANSYS HFSS environment. The eigenmode solver of ANSYS HFSS was used to determine different resonant frequencies. This was followed by examining a cylindrical corrugated waveguide that was implemented having a length of 17 mm for different conductor settings. The corresponding waveguide was fed by a plane wave having a resonant frequency that satisfies the intersection of the light line and dispersion curve of the corresponding mode. The analysis showed that the maximum loss factor was achieved at 39.20 and 40.07 GHz using ANSYS HFSS simulation data for different conductors, whereas ABCI resulted in 38.50 GHz. The talk will present the results gathered by different simulation setups implemented in ANSYS HFSS.

Speaker: Muhammed Unutmaz (SLAC National Accelerator Laboratory)

16:00 Evolution of Realistic Beam Distributions in Space-Charge-Dominated Electron Beams

Idealized models predict beam moments and envelopes, but not the detailed beam structure within those envelopes. We explore in experiment and simulation the interplay of space charge and angular momentum with realistic beam distributions in a low-energy transport system. Our realistic phase space distributions derive from direct experimental measurements near the beam source. The platform for this work is our Long Solenoid Experiment (LSE), a beam line designed to explore flat-to-round (FTR) and round-to-flat (RTF) beam transformations where space charge is a significant factor. Our transport system employs a thermionic electron gun, a slit mask, and skew quadruples to generate and manipulate flat beams with emittance ratios up to 20:1. The LSE is equipped with a sliding view-screen, enabling detailed phase space diagnostics over multiple plasma periods. We present simulations, initialized with realistic phase space distributions and validated against experimental results, that reveal the sensitivities of transverse beam dynamics to specific initial conditions and lattice parameters.

Speaker: Shiyi Wang (University of Maryland, College Park)

16:00 Explicit symplectic representations of nonlinear dipole fringe field maps

The representation of beam transport through magnetic dipole fringe fields using effective "thin" maps has a long history. More recent work has extended the second-order Taylor model of Brown by providing Lie generators for symplectic maps that capture effects at higher order, expressed in terms of field integrals. These maps can be cumbersome to evaluate in an explicit symplectic form appropriate for particle tracking codes, and existing approaches often require additional approximations. We show how such maps can be recovered in a simple, explicit form as rational symplectic functions using a mixed-variable generating function approach.

Speaker: Chad Mitchell (Lawrence Berkeley National Laboratory)

16:00 Exploring space charge mitigation with eigenpainting at the SNS

The Spallation Neutron Source uses charge exchange injection of 1.3 GeV, H- ions to accumulate roughly 2x10E protons per pulse in the accumulator ring. This is achieved using a flexible painting system capable of controlling all four transverse coordinates of injected beam over the 1ms injection cycle. Recently we demonstrated injection of an ~800 MeV beam into a single non-planar mode in the SNS ring, which we call eigenpainting. This poster will outline future plans for exploring the space charge dynamics of beams prepared by eigenpainting in the SNS ring, including comparison of hollow, gaussian, and uniformly painted beams.

Speaker: Nicholas Evans (Oak Ridge National Laboratory)

16:00 Extracting symplectic maps for space charge dominated beams

Symplecticity of 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 Extreme focusing of high-energy beams using near-field coherent transition radiation

The emission of transition radiation as a relativistic beam passes through a metallic foil usually has negligible impact on the high-energy beam itself. However, if the beam has very high current, such as those from the FACET-II facility, the near-field of the transition radiation can provide a strong focusing force on the beam which can be enhanced by passing through multiple closely spaced foils. This extreme focusing of high-energy beams opens a new physics frontier with unprecedented beam densities, potentially approaching that of a solid. The E-332 experiment at SLAC National Accelerator Laboratory has reached a first critical milestone with the experimental demonstration of this focusing effect from the collective interaction between a high-energy beam and a multifoil target. This result and future plans will be presented at the conference.

Speaker: Douglas Storey (SLAC National Accelerator Laboratory)

16:00 Fast differentiable simulations via dynamic multi-framework compilation

There is growing interest in differentiable simulations that have fast execution time and yield additional gradient information of physical observables with respect to design parameters. Existing differentiable codes have focused on picking a specific codebase and then reimplementing standard simulation algorithms - matrix and symplectic drift-kick tracking. This approach can be limiting due to various performance/compilation/ease of use tradeoffs of the chosen framework, especially for specialized GPU/TPU/other accelerator devices. We present a new library for differentiable simulations, JACC, that combines several numerical differentiation methods (Jax, PyTorch, NVIDIA Warp, finite differences) with an intelligent beamline generator that hardcodes fixed parameters into tracking kernels. This enables easy JIT traceability and kernel fusion, improving performance as compared to generic elements. Common Xsuite elements are implemented, and results carefully benchmarked. Furthermore, we provide templates for elements based on physics-informed neural networks and Gaussian processes, supporting arbitrary (reduced-fidelity and very fast) models. Examples of optics design and differentiable space charge tracking are discussed, demonstrating usefulness for injector design. We discuss implementation challenges and how to keep up with a rapidly changing ML ecosystem.

Speaker: Nikita Kuklev (Fermi National Accelerator Laboratory)

16:00 Fast spin tracking using a Magnus expansion

Spin motion in particle accelerators obeys the Thomas-Bargmann-Michel-Telegdi (T-BMT) equation. Due to the structure of the T-BMT equation, the spin-transfer quaternion of a magnet is generally a nonlinear function of the entrance coordinates even if the phase-space motion is linear. This nonlinear function can be written as a Dyson expansion, for example as employed in the program SPRINT, which normalized the first-order expansion of the spin-transfer quaternion. Alternatively, this nonlinear function can be written as a Magnus expansion. This paper points out that in cases where the phase-space coordinates change little, as is generally the case for accelerator elements, the Magnus expansion is a much more appropriate method to describe the nonlinear spin motion because this expansion terminates after the first term when the phase-space coordinates are constant. We will demonstrate, with several examples, that an approximation based on the Magnus expansion leads to very good agreement with time-consuming numerical integration, and to significantly better agreement than obtained with historical codes like SPRINT.

Speaker: Eiad Hamwi (Cornell University (CLASSE))

16:00 First observations of dispersive shock waves from the KdV equation in an electron beam

We present the first experimental observation of dispersive shock waves (DSWs) in an electron beam. Using the University of Maryland Electron Ring (UMER), a 10 keV electron beam was perturbed with a localized beam velocity dip. The resulting current profiles evolve into oscillatory structures consistent with dispersive shock behavior governed by the Korteweg–de Vries (KdV) equation. These results are predicted by particle-in-cell simulations using the WARP code. The observed dynamics open new avenues for studying nonlinear longitudinal phenomena in intense beam systems.

Speaker: Hannah McCright (University of Maryland, College Park)

16:00 Generation of low-emittance bunches with selective collimation at the Argonne Wakefield Accelerator

The Argonne Wakefield Accelerator (AWA) facility’s drive-beam linear accelerator can generate electron bunches at a wide range of charge - from 100 pC to 100 nC. This gives us a unique opportunity to study selective transverse collimation as a method to increase beam brightness using various initial bunch charges. This paper presents numerical modeling of the scheme. Simulations were performed to explore the impact of a collimating aperture on emittance, scraping the outermost electrons and retaining only the inner core of the beam with the goal of maximizing the beam brightness for a 100-pC electron beam. An optimization of various beamline parameters, including the initial bunch charge, was done to produce possible operating points that generate the lowest emittance. These simulations inform an experimental campaign that is also discussed in this work.

Speaker: Emily Frame (Northern Illinois University)

16:00 High DC injection voltage photocathode e-beam sources

Laser switched photocathode sources are typically used to produce trains of polarized electron bunches for high performance accelerators. This paper consid-ers two high brightness, high charge-per-bunch, e-beam injector approaches that utilize laser gated cath-odes followed by DC beam acceleration sections com-prised of 1-3 grading electrodes. The use of grading electrodes provides reliable high voltage standoff between the plates themselves and ground. In the rectilinear beam source case in particular, we found that the uniformity of the emitted current density can have a major effect on final beam emittance and brightness.

Speaker: Brian Beaudoin (University of Maryland, College Park)

16:00 Impact of electron beam size ripple on proton emittance growth for EIC

The Electron-Ion Collider (EIC) employs a flat hadron beam to achieve high luminosity, with the proton beam's vertical emittance being an order of magnitude smaller than its horizontal one. The smaller vertical emittance is sensitive to external noise. This study examines electron beam size ripple, a narrow-band noise centered around $60~\mathrm{Hz}$ in the US. Through beam-beam interaction, the electron size ripple contributes to vertical emittance growth. Mitigation strategies are discussed to preserve the flat beam aspect ratio.

Speaker: Derong Xu (Brookhaven National Laboratory)

16:00 Impedance and wakefield studies of the EIC RCS 591 MHz five-cell cavity

The Electron-Ion Collider (EIC) is a next-generation accelerator complex designed to enable high-luminosity collisions between highly polarized electrons and light ions (e.g., He-3). A central component of its Electron Injection System (EIS) is the Rapid Cycling Synchrotron (RCS), which accelerates a single 28 nC electron bunch from 750 MeV to 5, 10, or 18 GeV using an array of 591 MHz five-cell superconducting RF (SRF) cavities—eight at the current design stage. To ensure stable acceleration of high-charge bunches, we conducted detailed impedance and wakefield studies of the SRF cavity structure using both frequency- and time-domain methods. Wakefield solvers (ECHO3D, ECHO1D, CST), eigenmode analysis, and multi-particle tracking with ELEGANT were employed to evaluate longitudinal and transverse impedance effects and to determine instability thresholds. These studies provide critical input for the cavity design and operating parameters required to preserve beam quality and stability in the RCS.

Speaker: Isurumali Neththikumara (Thomas Jefferson National Accelerator Facility)

16:00 Implementation of adjoint sensitivity analysis in WARP

The design of accelerator lattices involves evaluating and optimizing Figures of Merit (FoMs) that characterize a beam’s properties. These properties—hence the FoMs—depend on the many parameters that describe a lattice, including the strengths, locations, and possible misalignments of focusing elements. Often what is required is the gradient of the FoM with respect to each of the parameters. For systems that require numerical simulation, a naïve computation of a gradient requires one simulation for the “base case”, plus one additional simulation for each parameter of interest—a daunting effort in the case of computationally demanding simulations with many parameters. Adjoint techniques allow one to extract gradient information from one base-case simulation plus an additional one or two carefully prepared simulations.* We demonstrate these techniques using the accelerator simulation code WARP, and we present our proof-of-concept results using several different FoMs as the basis for adjoint analyses of a simple beamline with multiple parameters.

Speaker: Dan Abell (RadiaSoft (United States))

16:00 Instability threshold measurements in the IOTA ring at Fermilab

Nonlinear focusing elements enhance the stability of particle beams in high-energy colliders via Landau Damping, a phenomenon that acts through the tune spread these elements introduce. This experiment at Fermilab's Integrable Optics Test Accelerator (IOTA) aims to investigate the influence of nonlinear focusing elements on transverse beam stability by employing a novel method to directly measure the strength of Landau Damping. This method employs an active transverse feedback system as a controlled source of impedance to induce a coherent beam instability. The beam’s resulting growth rate and transverse feedback parameters can then be used to directly measure the stability diagram, a threshold which maps the system's stability conditions. A proof-of-principle experiment of this measurement method was first explored at the LHC, where the experiment at IOTA aims to map out the entirety of the stability diagram and to obtain the beam distribution function from the stability diagram, a procedure never done before that would enable one to obtain the beam distribution tails. Here we present the initial results of stability diagram data analysis, simulation results, and plans for further investigation.

Speaker: Mary Duncan (University of Chicago)

16:00 Interactions between the circulating beam and the injection foil at the Proton Storage Ring of LANSCE

At the Los Alamos Neutron Science Center (LANSCE), the injection system of the Proton Storage Ring (PSR) utilizes charge exchange via a stripping foil to convert H⁻ ions into H⁺. While beam losses caused by partially stripped neutral hydrogen atoms are a primary concern, interactions between the circulating beam and the injection foil also play a significant role in overall beam loss. Each stored proton interacts with the foil 30 times on average. As a result, large-angle scattering is a dominant cause of beam losses in beam dynamics simulations.
To mitigate these effects, a set of bump magnets is employed to gradually move the closed orbit away from the foil during the accumulation process. In this work, we first compare various foil scattering algorithms used in ring simulations against results from Monte Carlo (MC) codes. We then quantify the impacts of different bumping schemes, assess uncertainties related to injection offsets, generate interaction 2d-distribution on the foil for heat load simulations, and evaluate the effects of different injected beam distributions.

Speakers: En-Chuan Huang (Los Alamos National Laboratory), Joshua Yoskowitz (Los Alamos National Laboratory)

16:00 IOTA experiment for proton pulse compression at extreme space-charge

The longitudinal compression of intense proton bunches with strong space-charge force is an essential component of a proton driver for a muon collider. We propose a proton bunch compression experiment at the Integrable Optics Test Accelerator (IOTA) storage ring at Fermilab to explore optimal radio frequency (RF) cavity and lattice configurations. IOTA is a compact fixed-energy storage ring dedicated to beam physics R&D that can circulate a 2.5-MeV proton beam with extreme space-charge. Using ImpactX and its 3D space-charge solver, simulations indicate that bunch length can be rapidly reduced by a factor of at least two, without appreciable degradation in transverse beam quality, even under strong space-charge conditions. However, longitudinal defocusing presents a large effect in short-pulsed proton beams, and the optimization of bunch compression under such conditions is discussed.

Speaker: Benjamin Simons (Northern Illinois University, Fermi National Accelerator Laboratory)

16:00 JuTrack, a Julia-based auto-differentiable accelerator simulation code for advanced dynamics, scientific machine learning and optimization

JuTrack is a high-performance accelerator modeling and particle tracking package developed in the Julia programming language. With compiler-level automatic differentiation (AD), JuTrack enables fast and precise derivative computations for arbitrary differentiable simulation functions. It supports efficient modeling of complex collective effects such as space-charge forces, wakefields, and beam-beam interactions. Beyond conventional tracking simulations, JuTrack also incorporates a machine learning–based module for self-field modeling and convenience interface that brings data-driven and physics-driven model together. In this paper, we demonstrate the capability and performance of JuTrack through a broad set of beam dynamics applications and optimization across various accelerator types, including a synchrotron light source, a heavy-ion linear accelerator, and the colliders. Built on Julia’s high-performance architecture and user-friendly syntax, JuTrack provides a powerful tool for beam dynamics studies and accelerator design optimization.

Speaker: Jinyu Wan (Facility for Rare Isotope Beams, Michigan State University)

16:00 LANSCE beam transport model enhancement and validation

At the Los Alamos Neutron Science Center (LANSCE), accurate beam transport modeling is essential to understand the nature of beam instabilities and losses. The model analysis enables significant improvement in beam transport tuning. It is the key element in ensuring the beam envelope remains constrained and that the bunch structure is preserved as it traverses the distance from the 800-MeV Linac to the target stations downstream. Historically, all the high-energy beamlines (HEBT) have been simulated using the TRANSPORT code. We are developing enhanced beamline models in modern accelerator physics codes such as MAD-X or Elegant, which enable more detailed particle tracking and include some space-charge effects. These models may help us better understand the beam parameters during transport to the targets. In this report, we present our simulation models and, where applicable, compare them with experimental beam diagnostics data.

Speaker: Clara-Marie Alvinerie (Los Alamos National Laboratory)

16:00 Laser Control of Electron Beams for Future Colliders

We explore the possibility of using lasers to control the bunch intensity of electron and positron beams in high-energy colliders through Compton backscattering. We also investigate the use of hollow-core lasers for electron and positron beam collimation. This technology would allow for much higher beam intensities at colliders without the risk of damage to a physical collimation system.

Speaker: Spencer Gessner (SLAC National Accelerator Laboratory)

16:00 Lattice design for Low Energy Cooling in EIC HSR-IR2

Insertion Region at two o'clock (IR2) of the Relativistic Heavy Ion Collider will be modified to provide effective cooling for the Electron-Ion Collider (EIC). This paper summarizes the update of the HSR-IR2 lattice design to meet the evolving requirements of the EIC. The geometry has been redesigned to satisfy the yellow-to-yellow configuration. The injection optics is optimized to satisfy the Low Energy Cooling requirements and physical aperture.

Speaker: Derong Xu (Brookhaven National Laboratory)

16:00 Lattice design of a pulsed synchrotron chain for a muon collider sited at Fermilab

We present preliminary lattices for a rapid cycling synchrotron (RCS) chain based on a bottom up design for a 10 TeV parton center-of-momentum (pCM) muon collider sited at Fermilab. The smallest RCS rings in this lattice are 6.28 km in circumference and the largest RCS ring fitting fully within the Fermilab site is 15.5 km. To reach 5 TeV per beam, a single tunnel containing up to two rings is allowed to exceed the 15.5 km limit. Each ring is either a conventional RCS or a hybrid RCS. A conventional RCS relies on only iron dominated, ramped field magnets while a hybrid RCS relies on a combination of interleaved ramped field and superconducting fixed field magnets to achieve higher average magnetic fields while maintaining the high ramp rates achievable with iron dominated magnets. A pair of 6.28 km RCS rings and a 15.5 km RCS ring accelerate beams from 63 GeV to 1.54 TeV. Three scenarios for acceleration from 1.54 TeV to 5 TeV using an off-site tunnel are presented.

Speaker: Kyle Capobianco-Hogan (Stony Brook University)

16:00 Lattice refinements for nonlinear integrable optics in IOTA

Nonlinear integrable optics of the type proposed by Danilov and Nagaitsev place strict constraints on the lattice parameters in the matching section outside of the nonlinear insert. In particular, the effects of energy spread in the beam have significant effects on the stability of the system. Typical chromatic compensation using sextupoles has significant perturbative effects on the dynamics but is operationally necessary to suppress fast losses. Fast decoherence of kicked beam measurements limits the available signal for studies. Refinements to the IOTA lattice parameters based on this experience with electron beam operation are presented.

Speaker: John Wieland (Fermi National Accelerator Laboratory)

16:00 Linac to BAR/RCS transfer line design for EIC electron injection system

A transfer line has been designed for the Electron-Ion Collider (EIC) to transport electron bunches from the linac to the Rapid Cycling Synchrotron (RCS). In its initial operational stage, the line accommodates 1 nC electron bunches directly from the linac. To support a future upgrade involving a Beam Accumulator Ring (BAR), which will stack individual bunches to form high-charge 28 nC bunches, the design incorporates two switching dipoles enabling injection into and extraction from the BAR. Additionally, a beam dump has been included for operational flexibility and safety. The final segment of the line interfaces with the RCS through a modified Penner bend, preserving beam quality while satisfying geometric constraints. This layout ensures compatibility with both current and future operational modes of the EIC injection system.

Speaker: Bamunuvita Gamage (Thomas Jefferson National Accelerator Facility)

16:00 Matching the beam from AGS to the EIC Hadron Storage Ring with excellent emittance preservation

The Electron-Ion Collider (EIC), a next-generation accelerator facility, is being jointly developed by Brookhaven National Laboratory (BNL) and Jefferson Lab (JLab), and will be constructed at BNL. The EIC design builds upon the existing RHIC heavy-ion infrastructure, transforming the RHIC rings into the Hadron Storage Ring (HSR) with necessary modifications. To ensure optimal performance, it is critical to accurately match the beam from the injectors to the HSR in six-dimensional phase space, in addition to the match of positions and angles. Inadequate matching can lead to emittance growth, which negatively impacts the achievable luminosity of the collider. This report outlines the key constraints involved in the matching process and presents a systematic approach to achieving high-fidelity beam matching while preserving emittance quality.

Speaker: Anbang Jiang (Ward Melville High School)

16:00 Measurements and simulations of intrabeam scattering effects at NSLS-II

In this study, we present the latest measurements of intrabeam scattering (IBS) effects at NSLS-II and compare them with particle tracking simulations using ELEGANT. The growth of horizontal and vertical emittances, as well as bunch length and energy spread, is observed as a function of single-bunch current. Simulations, including IBS and longitudinal wakefields modeled using a broadband impedance model, are used to explain these experimental observations. The same approach is applied to the low-emittance NSLS-II upgrade, where IBS significantly impacts the machine performance.

Speaker: Aamna Khan (Brookhaven National Laboratory)

16:00 Measurements of the beam longitudinal properties in the Fermilab Linac

The Fermilab Linac delivers 400$\,$MeV, 25$\,$mA H$^-$ beam to a rapid cycling synchrotron called the Booster. Parameters of the Linac beam affect Booster performance and therefore quantifying them is important. The longitudinal bunch parameters are reconstructed using a Bunch Shape Monitor (BSM) installed in the middle of the Linac. For that, the bunch length is measured as a function of the phase of an upstream cavity and fitted to simulations. The cavity gradient and its phase with respect to the beam are recovered from readings of Beam Position Monitors. Since the cavity provides a significant transverse defocusing, the BSM measurements are correlated with transverse beam size measurements by a wire scanner. Simulations connect these three types of measurements, allowing to deduce the longitudinal emittance and Courant-Snyder parameters.

Speaker: Ralitsa Sharankova (Fermi National Accelerator Laboratory)

16:00 Minimizing dispersion through resonant extraction for BNL's NSRL

Simulations, analysis, and measurements are performed on the BNL Booster’s third integer resonance extraction to the NSRL line, which uses a constant optics slow extraction method. In this method, ring dipoles and quadrupoles are changed synchronously for a coasting beam, which aids in maintaining a fixed separatrix orientation through the spill. Simulations show that the outgoing beam has a very small dispersion, independent of the periodic dispersion value at the septum. We show using a first-order normal form approximation that transforms to the Kobayashi Hamiltonian, how the dynamics of such a spill lead to a dispersion-free outgoing beam, which is critical to the uniformity requirements of the NSRL. Finally, we measure the dispersion of the beam by varying the flattop energy of the coasting beam in the booster before engaging the spill and show that the magnitude of dispersion is reduced by over a factor of 5 from the periodic value in the ring.

Speaker: Eiad Hamwi (Cornell University)

16:00 Mitigation of coherent synchrotron radiation by bunch profile optimization and shielding

The mitigation of the effects of coherent synchrotron radiation (CSR) is a key challenge in generating high brightness beams. Shielding by parallel plates installed in the dipole magnet vacuum chambers shows promise, both in simulation and experiment at small shielding gap separations. In this work, we consider a beam traversing a chicane with larger cm-scale separations on each dipole, necessitating the combined use of longitudinal profile shaping and shielding to reduce emittance growth. We model the radiated CSR using a 3D integrated Green's function technique that accounts for the complete 6D phase space of the bunch along with image charges to model shielding. This method is used in conjunction with a genetic algorithm to optimize the longitudinal current profile. Our results indicate current profiles that differ to results derived without shielding* and allow for effective mitigation of emittance growth at cm-scale gaps. We will present details of the simulation and optimization method along with future plans, including ongoing experiments at the Argonne Wakefield Accelerator as part of a collaboration that seeks to investigate the effects of CSR on beams.

Speaker: Omkar Ramachandran (Northern Illinois University, Argonne National Laboratory)

16:00 Mu2e resonant extraction regulation system simulation in delivery ring

Mu2e is an upcoming experiment at Fermilab that relies on the slowly extracted 8 GeV proton beam from the Delivery Ring. The experiment imposes strong requirements on the spill uniformity. To address these requirements, the fast spill regulations system is being developed and commissioned. To inform this development and optimize the system performance we are carrying out the detailed simulations of the regulation process. The simulation includes the effect of six harmonic sextupoles that excite the third-integer resonance and three fast ramping quadrupoles that drive the horizontal tune to 29/3. The components of spill regulation system are designed to mitigate long-term drifts in the beam, ensuring stable operation over extended timescales, as well as addresses rapid variations within single spill. In this study, we review the regulation system design, simulation of the slow regulation, and the fast regulation PID regulation to curtail random variations in the extraction rate that could occur within a single spill.

Speaker: Aakaash Narayanan (Fermi National Accelerator Laboratory)

16:00 Multi-objective optimization of Strong Hadron Cooler Energy Recovery Linac injector

The Strong Hadron Cooler (SHC) proposed for the Electron-Ion Collider (EIC) requires high-current, low-emittance electron bunches with minimal energy spread. The Energy Recovery Linac (ERL) injector plays a critical role in shaping the beam before acceleration. We present a multi-objective optimization study of the SHC ERL injector and merger using space charge tracking in Bmad and parallel genetic algorithm. The optimized configuration reduces the normalized transverse emittance by 62% and energy spread by 85% from the original configuration.

Speaker: Ningdong Wang (Cornell University)

16:00 Multiple interaction points in Ghost collisions

The Ghost Collider makes use of unique “ghost” bunches, which are electrically neutral combinations of electrons and positrons within the same RF bucket, eliminates the beam-beam effects typically present at the interaction point (IP) in conventional colliders. This allows for the novel possibility of placing multiple interaction regions in series, achieving additive luminosity without introducing significant disruption. However, to get higher luminosity, the beta functions at the IP reaches millimeter scale, which in turn adds significant chromatic contribution to the collider. Correcting these chromatic effects is essential to maintain beam stability and ensure high luminosity during collider operation. By carefully adjusting the phase advance between two IRs that are placed in series, it becomes possible to cancel chromaticity globally, enabling stable collider operation while preserving high luminosity. In this paper we discuss the design of such IR/IRs to be used in a ghost collider.

Speaker: Bamunuvita Gamage (Thomas Jefferson National Accelerator Facility)

16:00 New measurement techniques for gear-changing research using DESIREE

In this work we cover some of the newer techniques developed to measure the effects of a gear changing system maintained in DESIREE at Stockholm University. Gear-changing is a collider synchronization method where two rings with different harmonic numbers in them maintain collisions through different velocities, pathlengths or a combination of the two. This system has been demonstrated using the low energy ion collider DESIREE at Stockholm university. We have not only continued our previous methods of studying the beam using a repeating pattern technique where one bucket in each ring is intentionally left empty, but we now also use recently installed pickups outside of the merger region to study the beams separately while they collide.

Speaker: Edith Nissen (Thomas Jefferson National Accelerator Facility)

16:00 Odin klystron modulator for high power applications

Stangenes Industries is developing a novel klystron driver capable of peak modulator powers of 160MW and average powers of 320kW to drive a variety of high-powered electron-sources. The all-solid-state modulator consists of Marx-generators driving parallel primaries of a pulse transformer achieving output voltages of over 500kV. Over 3000 hours of internal lifetime testing on the primary pulsing components have proven the ruggedness of the design.

Pulse flat-tops of 0.1%/us are achievable with real-time klystron feedback, coupled with an optimization algorithm that automatically adjusts pulse parameters. Pulse RMS stabilities of less than 100ppm are necessary in many applications and require careful tuning of the charging elements.

For over 50 years Stangenes Industries has designed a built high quality electromagnetic components allowing for great advancements in science and industry. Stangenes is the logical choice for electron source drivers for pulsed electron guns, magnetrons, gyrotrons, and klystrons. All products manufactured by Stangenes Industries are made in the United States.

Speaker: Christopher Yeckel (Stangenes Industries)

16:00 Online regularization of Poincare map of storage rings with Shannon Entropy

A measurable chaos indicator is used as the online optimization objective in tuning a complicated nonlinear system - the National Synchrotron Light Source-II (NSLS-II) storage ring. Through analyzing the Shannon entropy in measured Poincar$\acute{e}$ maps, not only can the commonly used nonlinear characterizations be extracted, but more importantly, the chaos can be quantified, and then used for an online regularization of these maps. The method itself is general and applicable to other tunable nonlinear systems as well.

Speaker: Yongjun Li (Brookhaven National Laboratory)

16:00 Optical properties of wigglers with high field-to-energy ratio

One of the options to bring electron cooling to high energies is to employ an electron storage ring, which utilizes damping wigglers to counteract emittance growth of electron bunches used to cool hadrons. An example of such a cooler is the Ring Electron Cooler (REC) that can find potential future applications in Electron Ion Collider. The REC is designed to operate at 150 MeV and requires wigglers with peak field of 2.4 T. This unique combination a strong field wiggler operated at a relatively low energy results in unusual optical properties. In this paper we derive analytic formulas for focusing and chromaticity of different wiggler options and compare analytic and beam tracking results. While our analysis was used to optimize chromaticity in the REC, the derived formulas have a general applicability to wigglers with a high field-to-energy ratio.

Speaker: Sergei Seletskiy (Brookhaven National Laboratory)

16:00 Optics reconstruction in the SCL section of the FNAL Linac

The Side-Coupled Linac (SCL) section of the FNAL linac accelerates the beam from 116 MeV to 401.5 MeV, operating at 22-24 mA beam current. Transverse focusing is performed by 32 quadrupoles, and the beam orbit is guided by 19 dipole correctors and measured by 29 BPMs. The bunch length is measured in a single location by a Bunch Shape Monitor (BSM). This paper presents a three-step reconstruction of the machine optics. First, the transverse and longitudinal Twiss parameters at the start of the SCL section are determined using quadrupole scans and BSM measurements at different settings of an upstream cavity. Second, the quadrupole calibrations are adjusted based on differential-trajectory measurements. Finally, the beam is propagated along the SCL linac using the code TraceWin. A comparison between TraceWin simulations and the beam envelope measured by the 12 wire scanners of the SCL linac was performed. Transverse and longitudinal beam parameters at the entrance and exit of the SCL section will be reported.

Speaker: Abhishek Pathak (Fermi National Accelerator Laboratory)

16:00 Optimizing 4D emittance measurements using the pinhole scan technique

Accurate measurement of electron beam emittance is essential for optimizing high-brightness electron sources. The Pinhole Scan Technique measures the 4D phase space and hence the emittance by measuring the beam profile after clipping the beam using a pinhole followed by a drift section and then scanning the beam over the pinhole. This technique has been implemented in low (< 200 keV) beamlines at both Cornell university and Arizona State University. However, the technique poses several practical challenges. In this work, we analyze and address key issues affecting the 4D phase space and emittance measurements using this technique. We identify and investigate sources of inaccuracies like the pinhole aspect ratio, beam divergence, position-momentum correlations in the phase space, and the point-spread-function of the detector and suggest techniques to minimize them. Our findings offer a pathway to more accurate 4D phase space characterization in advanced electron beam systems.

Speaker: Peter Owusu (Arizona State University)

16:00 Overview of FCC-ee beam-beam studies

Achieving the ambitious luminosity target at the proposed Future Circular Collider e+e- (FCC-ee), collisions with high intensity and small beam size are required, limiting the choice of design parameters. As a result, the beam dynamics at the FCC-ee will be dominated by beam-beam effects at collisions, and the interplay of these with various other beam dynamical effects in the machine, such as impedances, electron cloud and lattice nonlinearities. The study of the resulting complex dynamics requires the usage of sophisticated and efficient numerical tools. This contribution aims to give an overview on FCC-ee beam-beam studies, highlighting key results, tool developments and challenges.

Speaker: Peter Kicsiny (European Organization for Nuclear Research)

16:00 Passive higher-harmonic RF cavity simulations for bunch lengthening in the NSLSII-U

In this study, we present a comparative analysis of passive higher-harmonic cavity (HHC) simulations with beam loading compensation using the particle tracking codes ELEGANT and SPACE. By cross-verifying results from both codes, we assess their accuracy in modeling beam dynamics under passive HHC operation for different filling patterns. Our findings demonstrate consistent outcomes between ELEGANT and SPACE, validating their effectiveness in simulating passive HHC systems with beam loading compensation. This work provides valuable insights for optimizing beam stability and performance in storage rings with HHCs.

Speaker: Aamna Khan (Brookhaven National Laboratory)

16:00 Phase variation for snake matching in the EIC's HSR

The Hadron Storage Ring of the Electron-Ion Collider will feature 6 Siberian snakes placed at the start of each arc to coherently cancel spin precession from diametrically opposite arcs in the ring. To avoid spin-orbital resonances, the alternating sum of the rotation axes of all snakes is 90 degrees, ensuring the closed-orbit spin tune is ½ and sufficiently far away from betatron tunes and integer tunes. This choice does not account for amplitude-dependent spin tune (ADST) shift, which introduces high-order spin orbit resonances in the vicinity of strong first-order resonances. By varying betatron phase advances across each of the 6 arcs, we minimize the strength of first-order spin-orbit resonances as well as ADST shift. In the case of uncooled helium-3, we find it is necessary to minimally vary the vertical orbital tune as well but are able to completely avoid depolarization throughout the ramp with time-dependent phase advances.

Speaker: Eiad Hamwi (Cornell University)

16:00 Power loss induced by welding beads in the HSR beam screen of the Electron-Ion Collider

GdfidL has been used to calculate the resistive wall heating in the vacuum components of the Electron-Ion Collider (EIC). In this paper, we present the simulation results for the beam-induced resistive wake potentials in various vacuum components of the EIC, including the beam screen and the hadron polarimeter in the hadron storage ring (HSR). The resistive wall losses are calculated from the wake potential computed in the finite-difference 3D electromagnetic code GdfidL and compared to the results obtained from the time-domain solver of another 3D electromagnetic code CST.

Speaker: Gang Wang (Brookhaven National Laboratory)

16:00 Preliminary experimental analysis of CSR shielding effects in a chicane compressor

We present preliminary analysis results from a recent experiment investigating CSR shielding effects on a beam propagating through a chicane compressor. The experiment was conducted at the Argonne Wakefield Accelerator (AWA) facility. Two identical doglegs with reversing quadrupoles—flip the beam—allow the beamline to function as a chicane. Shielding gaps of 1, 2 , and 3 cm were tested using manually adjustable plates inside the dipole magnet chambers. The longitudinal phase space was measured both upstream and downstream of the chicane. To compare CSR-dominated propagation with ignorable CSR case, a wide slit was also applied to cut the beam charge.

Speaker: Gwanghui Ha (Northern Illinois University)

16:00 Preliminary study of space charge and beam-beam interplay in a collider ring

Hadron Collider Rings offer unprecedented opportunities to address fundamental scientific questions in particle and nuclear physics. To achieve these ambitious goals, the colliders must deliver exceptionally high levels of luminosity, hence require high intensity hadron beam in the ring, which leads to high beam-beam parameter, as well as comparable space charge effects.
This study focuses on nonlinear effects that impact the beam dynamics within the hadron accelerator ring, including weak-strong beam-beam interactions and their interplay with space charge effects. Accurately predicting these non-linearities, particularly resonances arising during multi-turn acceleration, is critical for long beam lifetime and optimal
accelerator performance. This work presents an initial attempt to develop an optimized approach that integrates space charge effects across the entire ring length while incorporating localized beam-beam interactions at specific interaction points.

Speaker: Helena Alamprese (Michigan State University)

16:00 Progress toward dual-pulse operation at the Proton Storage Ring of LANSCE

Significant progress has been made in both hardware development and simulation capability to shorten the proton bunch width delivered to the Lujan Center at LANSCE via the Proton Storage Ring (PSR). We have successfully demonstrated operation of the PSR RF buncher at 5.6 MHz, doubled from the standard running condition, to accumulate the shorter beam pulse. A quick switch between two modes is under consideration. To extract the beam properly, a prototype kicker test stand has been established, and the measurement of the pulse width, rise time, and charging time will be demonstrated. On the simulation front, beam dynamics models have been refined using both ELEGANT and pyORBIT codes to optimize dual-pulse stacking scenarios. We have performed detailed studies of longitudinal phase space evolution, space charge mitigation, and bunch separation fidelity, which guide ongoing design efforts and beamline integration. These advancements will be the foundation for future development of shorter pulses for the Lujan Center.

Speakers: En-Chuan Huang (Los Alamos National Laboratory), Mr Heny Patel (Los Alamos National Laboratory)

16:00 Realistic simulation of the 76-inch cyclotron: COMSOL magnetic-field export integrated with an opal particle-tracking model

Accurate studies of particle behavior in accelerator chambers require precise magnetic field maps with regard to the iron geometry. We generated a realistic magnetic-field map for the 76-inch cyclotron at Crocker Nuclear Lab using COMSOL Multiphysics, then imported it into the OPAL (Object-Oriented Parallel Accelerator Library) software to model particle trajectories. It accurately simulates beam dynamics, provides reliable validation against measured data, and establishes a foundation for future cyclotron optimization and upgrades.

Speaker: SHUCHENG PAI (University of California, Davis)

16:00 Recent progresses regarding enclosed RF cavities for future muon collider cooling channel

The muon collider (MuC) holds strong potential for reaching the 10 TeV energy frontier but introduces several technical challenges. Ionization cooling is essential to reduce beam emittance and achieve required luminosities. As muons lose energy in absorbers, normal-conducting RF cavities restore it. However, strong magnetic fields—needed for beam focusing—increase the risk of RF cavity breakdowns. Thin beam windows are used to reduce breakdown probability and improve shunt impedance. In this paper, we present some recent studies on these cavities, including: 1) evaluating emittance growth due to particle scattering in the beam windows made of Be and Al by GEANT4, 2) calculating the beam loading effect in the presence of the beam windows with CST wakeifeld solver and Particle-In-Cell solver, 3) deriving the breakdown thresholds for different cavity materials in strong B fields based on a thermal-mechanical model.

Speaker: Dillon Merenich (Northern Illinois University)

16:00 Selection of Ion Sources for Modernization of the LANSCE Front End

We discuss selection of ion sources for the LANSCE Accelerator Modernization Project (LAMP). LANSCE currently operates both an H+ and H− ion source, providing beams to five independent user facilities. The H+ source is a duoplasmatron that provides protons for the Isotope Production Facility (IPF). The H- source is a surface-converter ion source configured with two tungsten hot filaments that provides beam to the other four LANSCE user facilities. To meet beam delivery requirements, the LAMP conceptual design has one H+ ion source and two H− ion sources. The upgraded sources in the LAMP conceptual design are two SNS (Spallation Neutron Source) style RF H− ion sources and an upgraded duoplasmatron for the H+ source.

Speaker: Leanne Duffy (Los Alamos National Laboratory)

16:00 Simulation Study of Particle Loss in Synchrotron Phase Space Injection for ESR Using Weak-Strong Beam-Beam Simulation with Nonlinear Lattice

In this study, we use tracking simulations to investigate synchrotron phase-space injection for electron accumulation in the electron storage ring of the Electron-Ion Collider. Our simulation model incorporates both beam-beam interactions and lattice nonlinearities. Specifically, we examine how particle loss depends on various parameters. Our results demonstrate the feasibility of synchrotron phase-space injection for the electron storage ring and provide insights to guide parameter selection in the design of the injection line.

Speaker: Yi-Kai Kan (Brookhaven National Laboratory)

16:00 Simulations of CSR and LSC induced microbunching in the presence of a laser heater

We present a study of microbunching instability in the FACET-II linac, in which the amplification and damping mechanisms are analyzed separately. Our simulations investigate the gain induced by Longitudinal Space Charge (LSC) and, critically, the damping caused by nonlinear terms in the beam transport transfer map. We show theoretically and through simulation that these nonlinear effects can produce damping several orders of magnitude stronger than predicted by linear theory.

Experimental evidence validates these findings. A quadrupole scan performed in the FACET-II dogleg reveals that an interaction between coherent betatron oscillations and transfer map nonlinearities shifts the point of minimal damping away from the expected linear condition of $R_{51}=0$. The strong agreement between our simulations and the experimental data demonstrate that a thorough understanding of nonlinear dynamics is essential for high-brightness beam transport.

Speaker: Sergei Kladov (University of Chicago)

16:00 Single-bunch instabilities driven by space charge during low-energy cooling at injection in the EIC Hadron storage ring

This paper presents a simulation-based study of single-bunch dynamics at the injection energy of 23.8 GeV for protons in the EIC hadron storage ring, focusing on the impact of space-charge–driven instabilities. The analysis demonstrates that at this energy, the proton bunch experiences significant transverse space-charge forces, which can reduce the stability margin in the presence of the geometric and resistive wall impedance. Various collective effects were considered, with particular attention to the nonlinear nature of the transverse space charge. To stabilize the beam, high chromaticity and octupoles were introduced and their effects analyzed using the ELEGANT code. The results provide a quantitative assessment of the stability thresholds and offer guidance for the machine design and operational strategy at injection.

Speaker: Alexei Blednykh (Brookhaven National Laboratory)

16:00 Space charge studies on strong hadron cooler energy recovery linac

An Energy Recovery Linac (ERL) based cooler, using Coherent electron Cooling (CeC) is being designed for cooling hadron beams of the Electron-Ion Collider (EIC). The ERL design utilizes highcurrent, high-brightness electron beams with low emittance and a uniform longitudinal distribution for efficient hadron cooling. This is designed to operate in two modes to accommodate cooling requirements for hadron bunches at 100 GeV and 275 GeV, each with an average current of 100 mA and 1 nC bunch charge. With these parameters, the space charge effects become significant in this ERL design due to the low beam energy and high beam current. In this paper, we discuss strategies for including space charge effects in the optics design and implementation of an interface for space charge dominated and non-dominated regions of this ERL lattice.

Speaker: Isurumali Neththikumara (Thomas Jefferson National Accelerator Facility)

16:00 Start-to-end simulation study for transverse wiggler-based manipulation experiment

We present a simulation study to support the planning of experimental demonstrations of transverse wiggler-based correlation control. While previous simulations confirmed the feasibility of this approach, they did not incorporate realistic field maps of the transverse wigglers. In addition, the impact of various jitter and error sources—key concerns for experimental implementation—has not been analyzed. In this study, wiggler fields are generated through magnetostatic simulations and incorporated into start-to-end particle tracking simulations. The phase space responses to different jitter and error sources are also evaluated.

Speaker: Gwanghui Ha (Northern Illinois University)

16:00 Start-to-end simulations of nanometer-emittance beam transport through an emittance exchange beamline

We present start-to-end simulation study of the transport of a few pico-Coulomb, nanometer-emittance beam through an emittance exchange (EEX) beamline. EEX with nanometer-emittance beams has potential to enable research opportunities utilizing tunable and high quality attosecond bunches and nanometer-scale longitudinal bunch trains. To account future possibility of experimental demonstrations, the simulation implemented existing EEX beamline at Argonne Wakefield Accelerator (AWA) facility. Simulation was conducted using General Particle Tracer (GPT) code.

Speaker: Buse Naz Temizel Ozdemir (Northern Illinois University)

16:00 Start-to-end simulations of the LAMP accelerator front-end

The LANSCE Accelerator Modernization Project (LAMP) plans to replace the two existing 750-keV Cockcroft Waltons by a single radio-frequency quadrupole (RFQ), and to install a new 100-MeV drift-tube linac (DTL). LAMP will simultaneously produce H+ and H- beams with different timing patterns to serve multiple experimental facilities. A low energy beam transport (LEBT) is designed to transport H+ and H- beams from the ion sources into the 201.25 MHz RFQ, where the beams are accelerated to 3 MeV. A medium energy beam transport (MEBT) is designed to transport the beam from the RFQ to the DTL. The DTL accelerates both beams to 100 MeV. The LEBT and MEBT designs include beam choppers and rf systems that imprint the multiple timing patterns required by experiments. Here we describe a concept of the LAMP front-end and present particle simulation results for multiple beams relevant to the facility.

Speaker: Dr Salvador Sosa Guitron (Los Alamos National Laboratory)

16:00 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 the beam through the pair of LINACs. These FFA arcs will be composed of permanent magnets, with small Panofsky-style multipole correctors. Horizontal splitters are needed to control the beam parameters through these FFA arcs. 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: Ryan Bodenstein (Thomas Jefferson National Accelerator Facility)

16:00 The 10 TeV Wakefield Collider Design Study

We provide updates on the community-driven Design Study for a 10 TeV pCM Wakefield Accelerator Collider. The Design Study is motivated by the 2023 P5 Report calling for the “delivery of an end-to-end design concept, including cost scales, with self-consistent parameters throughout" targeting the energy frontier. The Design Study leverages recent experimental and theoretical progress from a global R&D program with the goal of delivering a unified, 10 TeV Wakefield Collider concept. Wakefield accelerators provide ultra-high accelerating gradients which enables an upgrade path to extend the physics reach of a Higgs factory linear collider beyond the electroweak scale. We describe the organization of the Design Study including timeline and deliverables, and progress made in 2025.

Speaker: Jens Osterhoff (Lawrence Berkeley National Laboratory)

16:00 The implementation of adaptive step size Runge Kutta integrator in Zgoubi

The Zgoubi simulation code for beam and spin dynamics employs a numerical method based on Taylor series to integrate the Lorentz and Thomas-BMT equations, optimizing computational efficiency while ensuring high accuracy and robust preservation of motion invariants. In this work, we developed and implemented an adaptive step-size Runge-Kutta (RK) integrator into Zgoubi to tackle growing computational demands in accelerator physics simulations. This new integrator complements Zgoubi's default solver, offering users the flexibility to choose between integration methods based on specific simulation requirements. We demonstrated that the adaptive step-size RK integrator achieves the necessary accuracy and performance for integrating the Lorentz and Thomas-BMT equations effectively.
A key advantage of Zgoubi lies in its wide optical elements library, featuring over 60 accelerator components and variants, which the new adaptive step-size RK integrator can seamlessly utilize. Developed and rigorously tested over decades across numerous projects, this library provides a high degree of confidence in the code’s reliability. The same advantage holds about ancillary computations such as synchrotron radiation, space charge, decay in flight, etc. The implementation of the adaptive step-size RK integrator supports Zgoubi’s adaptability, enabling simulations of complex beam and spin dynamics with a trusted and well-established computational framework.

Speaker: Bhawin Dhital (Brookhaven National Laboratory)

16:00 Third integer resonant extraction transit time simulation studies

In this work, we present the investigation of transit time of particles in the non-linear third-integer resonant extraction process. Transit time is defined as the number of turns a particle takes to get extracted once it is in the unstable region in the phase space, i.e., outside the triangular separatrix in case of third-integer resonance. The study of transit time is important because transit time directly contributes to the beam response time during resonant extraction and thus knowing it apriori would be practically useful in designing of the extraction system. In this work, we shall investigate the analytical derivation of the transit time of particles (to the first order Kobayashi Hamiltonian) in different parts of the phase space distribution and compare against the analytical results. We also compare the simulation result of the transit time of particles (with higher statistics) for the static as well as dynamic extraction conditions cases, particularly in the context of resonant extraction parameters for Mu2e experiment at Fermilab.

Speaker: Aakaash Narayanan (Fermi National Accelerator Laboratory)

16:00 Timing of ultrafast electron and laser pulses with narrowband THz interferometry for ultrafast electron diffraction

Ultimately, accurate time of arrival determination of laser pump and electron beam probe will determine the temporal resolution of the SLAC MeV-Ultrafast Electron Diffraction* (MeV-UED) instrument, and therefore methods to achieve this at femto-second scales is an ultrafast science enabler. Interferometry of THz based e-beam and pump laser THz signals is a natural path towards this goal. As a first step, a detection scheme will be developed in a lab using laser pulses. The second step involves extracting the electron beam signal from a 100 GHz accelerating structure. Subsequently, both pump and electron beam signals are combined, filtered, amplified, and a temporal analysis can be performed. This proposal is for experimental detection and characterization of such signals, which arises from electron beam wakefield excitation of electromagnetic fields in a 100/200 GHz accelerating structure combined with a pump derived signal.

Speaker: Stephen Weathersby (SLAC National Accelerator Laboratory)

16:00 Tolerances of RF phase and voltage noises with beam-beam interaction in the Electron-Ion Collider

The Electron-Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized high-energy electron beams with polarized proton and ion beams, achieving luminosities of up to 1 × 10^34 cm^−2 s^−1 in the center-of-mass energy range of 20–140 GeV. We have studied the impacts of various machine noises on beam emittance growth in the presence of beam-beam interactions. These noises include power supply current ripples, crab cavity phase and voltage noise, and intrabeam scattering. In this article, we present our recent simulation studies on the effects of phase and voltage noise from the storage RF cavities in both storage rings of the EIC: the electron storage ring (ESR) and the hadron storage ring (HSR). The goal of this study is to determine the tolerances for RF phase and voltage noises in the EIC storage rings and to provide important input for the EIC RF engineering design.

Speaker: Yun Luo (Brookhaven National Laboratory)

16:00 Towards differentiable beam dynamics modeling in BLAST/ImpactX

Differentiable simulations are in demand in accelerator physics, demonstrating order-of-magnitude improvements for complex tasks such as many-parameter optimization for accelerator working points and reconstruction of hard-to-measure quantities. At its core, a differentiable simulation does not only solve a forward problem, but additionally provides gradients of output parameters (e.g. beam parameters) with respect to input parameters (e.g. beamline or source parameters).
How to effectively program large dynamic simulations differentiably is still an open question, but there is general consensus that a “single-source” approach aided by automatic differentiation (AD) is desirable. Addressing this, there are a) emerging domain-specific languages in machine learning that are intrinsically differentiable, and b) highly-performing & scalable, general-purpose languages like ISO C++ of existing codes. The challenge of approach a) is syntax specialization, which can limit ease of implementation & performance for physics algorithms, while b) requires additional work for AD.
Performance is important for modeling high-order beam dynamics and collective effects in accelerators. We compare the fast, modern codes ImpactX (C++/Python) and Cheetah (PyTorch) using traditional, gradient-free modeling. We then show progress in introducing single-source differentiability in ImpactX using modern compiler techniques, producing performant executables for gradient-based and gradient-free modeling.

Speaker: Axel Huebl (Lawrence Berkeley National Laboratory)

16:00 Transverse beam dynamics studies in the FRIB accelerating cryomodules

The accelerating segments in the Facility for Rare Isotope Beams (FRIB) linac contain superconducting RF cavities accelerating the beam and superconducting solenoids providing transverse focusing. We have studied the transverse emittance growth in the post-stripper linear accelerating segment of the FRIB linac. To understand the cause of the emittance growth we employ a macroparticle tracking code to simulate 3D beam dynamics in this segment of the linac. The model is being developed and validated by beam measurements. The measurements are focused on the response of the transverse beam position along the segment after the beam is kicked by dipole steering magnets at the entrance to this segment. The results of the studies with various beam species and energies will be presented.

Speaker: Alec Gonzalez (Facility for Rare Isotope Beams)

16:00 Update of the EIC HSR injection system design

The Electron-Ion Collider (EIC), to be constructed based off the existing RHIC facility, will collide electrons with multiple species of hadrons. The Hadron Storage Ring (HSR), based largely on the Yellow RHIC ring, will accommodate three times the number of bunches compared to RHIC. A completely new HSR injection system will be developed to meet these requirements. This report presents the design of the HSR injection system, including the warm transfer lines, the septum design, the injection lattice optimized to reduce the required kicker strength, and the design and testing of the injection stripline kicker.

Speaker: Chuyu Liu (Brookhaven National Laboratory)

16:00 Vertical emittance growth from IBS diffusion via beam-beam coupling in the EIC

We investigate vertical emittance growth in the Electron-Ion Collider (EIC) arising from intrabeam scattering (IBS) diffusion through beam-beam interactions. Using weak-strong simulations, we demonstrate that when horizontal noise is introduced, vertical emittance increases even in the absence of direct vertical diffusion. This behavior is attributed to resonance streaming around the synchro-betatron resonance $2\nu_x-2\nu_y+p\nu_z=0$, which enables unidirectional emittance transfer from the horizontal to the vertical plane. We further show that horizontal cooling alone cannot suppress the vertical growth, confirming that dedicated vertical cooling is essential for preserving the flat beam profile in high-luminosity EIC operation.

Speaker: Derong Xu (Brookhaven National Laboratory)

18:00 → 19:15 EIC & FCC Discussion Parallel #2 - https://indico.global/event/15398/overview

Agenda at: https://indico.global/event/15398/overview

19:30 → 21:30 Early-Mid Career Networking Session (Plenary Room)

Food and drink provided; Goal: Connect EC attendees with other ECs and Senior members of the field to learn about job opportunities and prospects.

Early-Mid Career Networking Panel: 30-45 minutes (7:45PM - 8:30PM)
Topics for the panel: Educate EC attendees about career paths in accelerator physics; Demands on the US accelerator workforce; Education/training/planning for workforce; Advocacy beyond HEP; Opportunities in industry; Opportunities in lab operations; Opportunities in lab R&D.

Wednesday 13 August

08:00 → 09:00 Coffee

09:00 → 10:30 Wednesday Tutorial

09:00 Harnessing Nonlinearity in Beam Optics

This tutorial will revise key topics in nonlinear accelerator dynamics, including detuning, integrability and quasi-integrability, chaos detection, symmetries, and approximate invariants. We will examine the complexities of dynamic aperture in modern accelerator design, with a focus on the delicate balance between long-term stability and resonance overlap. This part will address the practical challenges of defining and evaluating the regions of phase space accessible to particles, and the impact these considerations have on machine performance.

Building on this foundation, we will highlight recent theoretical advances in integrable and quasi-integrable optics, outlining potential strategies for designing alternative beam lattices that sustain stable, structured nonlinear motion and help reduce particle losses.

In the final section, we will discuss the introduction of nonlinear Courant–Snyder invariants and demonstrate their practical application in operating accelerators, drawing on examples from the Fermilab complex.

Through this comprehensive tutorial, participants will gain a deeper understanding of both fundamental principles and modern techniques for managing nonlinearity in accelerator systems, better equipping them to tackle the dynamic challenges of today’s high-performance machines.

Speaker: Timofey Zolkin (Independent Researcher)

09:00 → 09:30 Accelerator Technology and Sustainability (Invited)

09:00 Accelerator workforce development

Accelerator science has been hugely influential on research, contributing to physics Nobel Prize-winning research every three years. The DOE Office of Science invests in accelerator science to sustain America’s excellence and constructs and operates large-scale scientific user facilities to be vital tools of discovery.

Developing the next breakthroughs in accelerator science, and designing, building, and operating user facilities, requires a large, highly skilled workforce of accelerator scientists, engineers, and technical (AS&E) staff. Some portions of the AS&E workforce are best planned with a long-term, national perspective in mind.

A roundtable meeting was called with participants comprising 9 DOE National Laboratories and the Office of Science Nuclear Physics User Facility FRIB. An approximate census of the current accelerator workforce at those institutions was assembled along with an approximate workforce projection with a 10-year horizon. Critical and endangered skillsets were identified and best practices for workforce development were shared.

In recognition of the wider ecosystem, plans were discussed to expand the roundtable participants to universities and critical members of the accelerator industry in the next year.

Speaker: Fulvia Pilat (Oak Ridge National Laboratory)

09:30 → 10:30 Accelerator Technology and Sustainability (Contributed)

09:30 Focusing of Relativistic Electron Beams With Permanent Magnetic Solenoids

Achieving strong focusing of MeV electron beams is a critical requirement for advanced beam applications such as compact laboratory X-ray sources, dielectric laser accelerators, and ultrafast electron diffraction (UED). To address these and similar relativistic electron focusing requirements, a compact radially magnetized permanent magnetic solenoid (PMS) has been designed, fabricated, and tested. The solenoid provides a compact and inexpensive solution for delivering high axial magnetic fields (1 Tesla) to focus MeV electron beams. Field characterization of the solenoid demonstrates excellent agreement with analytical models, validating the PMS design. The electron beam test employs a high-brightness photoinjector to study the focusing properties of the PMS. The results show a significant reduction in beam size with small spherical aberrations. Using the measured results, two application cases are evaluated: angular magnification in UED setups and strong focusing for Compton scattering or other microfocus uses.

Speaker: Tianzhe Xu (SLAC National Accelerator Laboratory)

09:50 Status of permanent magnet radiation resiliency studies at CEBAF

An ongoing investigation for the future of 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, using permanent magnets for the FFA arcs. A common concern among the community 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 permanent 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: Ryan Bodenstein (Thomas Jefferson National Accelerator Facility)

10:10 PMQ radiation resistance testing at NSLS-II

A new lattice for the NSLS-II upgrade is likely to use high strength (> 100 T/m) permanent magnet quadrupoles (PMQs). An ID beam exiting through these quadrupoles will place highly intense x-rays very close (~ 1mm) to the permanent-magnet material. In these tests the PMQs will be placed in the IFE (Instrumentation Front End) front end to assess any degradation of their field strengths and field quality due to long term exposure to an ID beam. The IFE beamline was recently commissioned at NSLS-II and is dedicated to testing the mechanical properties of accelerator materials and components. The description of the source and experimental setup will be given.

Speaker: Thomas Roff (National Synchrotron Light Source II)

10:30 → 11:00 Coffee

11:00 → 12:30 Applications of Accelerators, Technology Transfer, Industrial Relations, and Outreach (Invited)

11:00 A plan to revitalize the domestic superconducting radio-frequency industry

Superconducting radio-frequency (SRF) cavities are essential building blocks of modern particle accelerators for scientific research, and they offer unique capabilities that could be transformative for commercial applications. Growth of the domestic SRF industry in North America has faced several challenges over the past decades, as most of the international demand for cavities was supplied by European vendors. This contribution provides a brief review of the domestic industrial vendor space, an outlook of the global demand for SRF cavities and an outline of the challenges leading to this supply chain deficiency. One of the main challenges towards establishing a robust domestic SRF industry has been the large uncertainty in the demand. Meanwhile, research and development activities to raise technical readiness of SRF accelerators for industrial use have continued and several potential markets are emerging that may offer a consistent and growing demand for SRF cavities. Finally, reasons and means of establishing and sustaining competitive domestic suppliers are described.

Speaker: Gianluigi Ciovati (Thomas Jefferson National Accelerator Facility)

11:30 Accelerator-based medical isotope production: An overview of emerging trends and novel initiatives

Recent advances in drug development and radionuclide research have notably expanded the role of nuclear medicine in treating cancer over the past decade. Throughout such research and development efforts, the list of drug moieties and cancer types under investigation is paralleled by a similarly expansive list of radionuclides. This is because the suitability of a radionuclide for a therapeutic radiopharmaceutical application will depend on many factors including, but not limited to, the decay mode (e.g. α- vs β-emitter), the particle emission range, the matching of its half-life to the pharmacokinetics of the drug, and the co-emission of gamma rays of appropriate energy for imaging. Moreover, the successful adoption into clinical practice hinges on sustained, reliable, and cost-effective access to these radionuclides – a task which is not trivial. To this end, this presentation provides an overview of emerging trends in radionuclides (noting ²²⁵Ac, ²¹¹At, ¹⁷⁷Lu, and ⁶⁷Cu as examples), alongside novel initiatives for accelerator-based production strategies.

Speaker: Katie Gagnon (Nusano)

12:00 Application of Accelerator Technology to Quantum Information Science

The intersection of accelerator and quantum information science (QIS) offers a unique platform to advance both fields through shared technology and infrastructure. This talk will discuss the synergies which exist between these two vastly different but complementary domains. We demonstrate how we leverage pre-existing infrastructure and knowledge to perform research and development which helps to realize dramatic improvements in both 10 km long accelerators and 10 cm large quantum processors. We will explore niobium superconducting radio-frequency (SRF) cavities, a mature technology that excels in efficiently storing electromagnetic energy, enabling ultra-long photon lifetimes critical for quantum processors and facilitating the characterization of quantum materials with parts-per-billion precision. We will also discuss how advancements in superconducting materials, cryogenic systems, and control techniques help to reduce cost and improve performance for both quantum systems and particle accelerators. Moreover, we will discuss cross-disciplinary applications such as dark-matter searches and demonstrate the convergence of these fields in addressing fundamental scientific questions.

Speaker: Daniel Bafia (Fermi National Accelerator Laboratory)

11:00 → 12:30 Beam Instrumentation, Controls, AI/ML, and Operational Aspects (Invited)

11:00 Machine learning-enhanced deterministic controls in lasers and accelerators

Modern laser and accelerator systems demand fast, precise, and scalable multi-input multi-output (MIMO) feedback control. As requirements extend into high-repetition-rate and nonlinear regimes, traditional strategies increasingly struggle to deliver the necessary speed and adaptability. This talk presents two cases where machine learning (ML) enhances deterministic feedback control. In both, ML models—trained on experimental or simulated data—provide rapid predictions to guide real-time decisions. Integrated into conventional feedback loops, they substantially improve response speed and robustness across diverse operating conditions. At Lawrence Berkeley National Laboratory, ML feedback enabled the first preemptive pointing stabilization at the BELLA Petawatt beamline, achieving a ~60% reduction in jitter and reduced response time in a coherent beam combining system by nearly an order of magnitude. These results show that ML can increase speed, stability, and adaptability without compromising determinism, opening new opportunities for intelligent control in next-generation facilities.

Speaker: Dan Wang (Lawrence Berkeley National Laboratory)

11:30 Safe extremum seeking for real-time adaptive accelerator control

This talk presents Safe Extremum Seeking (Safe ES), a robust n-dimensional adaptive control method, applied to automatic tuning and optimization tasks of accelerators while guaranteeing that the system remains within safe operating conditions. A key strength of Safe ES is its ability to handle safety measures that are analytically unknown. For instance, the algorithm can adaptively tune quadrupole magnets to achieve a desired beam profile while maintaining safety by keeping beam losses below a user-defined threshold.

The presentation provides a comprehensive technical overview of this optimization technique, highlighting its theoretical foundations and practical applications. It includes simulation studies demonstrating its effectiveness for accelerator systems, as well as results from an in-hardware demonstration conducted on the LANSCE accelerator at LANL. Also, the talk explores how Safe ES can be integrated with generative machine learning models to enable adaptive machine learning.

Speaker: Alan Williams (Los Alamos National Laboratory)

12:00 Measurements of ultralow emittance and transverse coherence at the Advanced Photon Source Upgrade storage ring

Recent electron storage ring light sources continue to push towards increasingly lower electron beam sizes. In the present work, we report on the measurements of the electron beam emittance (sub 50 pm rad) achieved at the Advanced Photon Source Upgrade (APS–U), as well as its standing among electron storage ring light sources. We include a brief status update on the beam size monitor beamline at the APS–U. We conclude with a survey of measurement techniques and recent results across multiple laboratories.

Speaker: Kent Wootton (Argonne National Laboratory)

12:30 → 14:00 Lunch

14:00 → 14:30 Beam Dynamics and EM Fields (Invited)

14:00 Symplectic Neural Network Surrogate Models for Applications to Beam Dynamics

Development of robust machine-learning (ML) based surrogates for particle accelerators can significantly benefit the modeling, design, optimization, monitoring and control of these systems. It is advantageous for surrogate models to incorporate fundamental physical constraints governing beam interactions and dynamics, which are essential to the operation of an accelerator.

We investigate two classes of phase space structure-preserving neural networks — SympMat for linear beam dynamics and Henon Neural Networks (HenonNets) for nonlinear beam dynamics problems. For the linear case, we introduce a simple and effective parameterization of arbitrary linear symplectic matrices. To address potential nonlinearities in the parameter space, we employ a conditional parameterization strategy. For nonlinear beam dynamics, we develop parametric HenonNets with a universal symplectic approximation theorem. We demonstrate the effectiveness of the proposed symplectic neural networks through examples involving charged particle dynamics and both linear and nonlinear beam dynamics. Our results suggest that these symplectic neural networks can serve as promising ML-based surrogate models for complex beam dynamics systems.

Speaker: Qi Tang (Georgia Institute of Technology)

14:00 → 14:30 Photon Sources and Electron Accelerators (Invited)

14:00 Design progress for the 22 GeV CEBAF energy upgrade

In this work we examine the progress made in the design of the proposed FFA upgrade to the Continuous Electron Beam Accelerator Facility (CEBAF). This proposed upgrade will double the number of passes through the two linacs by replacing the two highest energy arcs with new Fixed Field Alternating Gradient (FFA) arcs, roughly doubling the energy. These FFA arcs will use permanent magnets in a Halbach configuration to shape their fields. The design involves new optics for the linacs and remaining electromagnetic arcs, as well as new electromagnetic separators. These feed into the permanent magnet FFA arcs. We also report on ongoing studies of the dynamics of the beams, and an experiment to measure the effects of radiation on the permanent magnets.

Speaker: Edith Nissen (Thomas Jefferson National Accelerator Facility)

14:30 → 15:30 Beam Dynamics and EM Fields (Contributed)

14:30 Simulations of IBS through electric field fluctuations

We present a study of intra-beam scattering (IBS) in high-brightness electron beams, incorporating a recent theory that accounts for enhanced temporal correlations of electric field fluctuations. These correlations, absent in conventional binary-collision models, arise from the periodic betatron motion of particles within the beam. To enable direct verification of the theoretical calculations, we perform simulations in a computer code specifically written for that purpose. In the code, the particle distribution is preserved over time, ensuring conditions compatible with theoretical assumptions, and the IBS is neatly separated from the conventional Space Charge (SC) effect.

The simulations, benchmarked against an exactly solvable case of an infinite isotropic uniform plasma, show good agreement with both uncorrelated models, such as Piwinski’s, and the new correlation-based theory, across various bunch distributions and dynamical regimes. This validates the simulation approach and highlights the role of time-correlated fields in accurate IBS modeling.

Speaker: Sergei Kladov (University of Chicago)

14:50 Computing spin-polarization in electron storage rings by machine learning via randomized Fourier neural networks

Our work addresses the challenge of estimating spin po-
larization in high-energy electron and positron storage rings,
such as the Electron Storage Ring (ESR) of the Electron-Ion
Collider (EIC) at Brookhaven National Lab (BNL) and those
in the electron/positron Future Circular Collider (FCC-ee)
at CERN. We model the spin and orbital motion of particle
bunches using the recently introduced spin-orbit Fokker-
Planck (SOFP) equation, a linear time-evolution partial dif-
ferential equation (PDE). In this paper, we propose a novel
machine learning (ML) approach leveraging a randomized
Fourier neural network (rFNN) framework*, specifically de-
signed to solve linear PDEs. We will discuss the SOFP high-
light its relevance to spin polarization studies, and share pre-
liminary results demonstrating the network’s performance
on the Poisson problem.

Speaker: Jose Agudelo (University of New Mexico)

15:10 Single-bunch instabilities at the Fermilab Recycler Ring

Understanding and characterizing collective instabilities is critical for high-intensity operation at the Fermilab Recycler Ring. This work presents an application of the the Nested Head-Tail (NHT) formalism for modeling single-bunch transverse instabilities, incorporating analytical solutions to the resistive wall and theta wake impedances in the absence of space charge. Predicted growth rates and mode structures are benchmarked against PyHEADTAIL simulations and ongoing experimental measurements. The experimental program includes studies of both bare-machine instabilities and beam behavior under transverse feedback (the Waker experiment), providing a comprehensive validation of the theoretical model. These results support the interpretation of Waker data and contribute to the development of predictive tools for beam stability in future high-intensity configurations.

Speaker: Cristhian Gonzalez-Ortiz (Fermi National Accelerator Laboratory)

14:30 → 15:30 Photon Sources and Electron Accelerators (Contributed)

14:30 LCLS-II injector operational challenges and recent developments

LCLS-II has been in user operations since 2023 and has ramped the beam rate up to 33 kHz to date. The LCLS-II photoinjector has demonstrated a low-emittance (half-micron) beam operating at a high rate. During the injector operation, we have also encountered several challenges, such as e-beam splitting and large dark current from the gun. The split e-beam compromises FEL lasing, while the large gun dark current generates substantial amounts of ions, which backbombard and damage the photocathode, as well as cause beam loss downstream, frequently damaging components. Recently, these problems have been successfully addressed. On one hand, a relatively larger laser size was implemented on the photocathode, which helped suppress space charge effects, resulting in the disappearance of the split beam. On the other hand, an over-inserted photocathode, recently installed on the LCLS-II gun, has reduced the gun's dark current by a factor of 1000. The gun dark current reduction has significantly extended the photocathode's operational lifetime, eliminated the QE and FEL intensity dependence on beam rate, and substantially reduced beam loss downstream. This paper presents detailed analyses and solutions for LCLS-II photoinjector operational challenges.

Speaker: Feng Zhou (SLAC National Accelerator Laboratory)

14:50 Effects of beam conditions on achieving compact longitudinal de-chirping using transverse deflecting cavities

It has been shown that a transverse deflecting cavity (TDC)-based de-chirper can be made by altering the drift sections in a TDC-based chirper to form negative drifts. While five appropriately configured quadrupole magnets can implement such negative drifts, this approach is limited by spatial and experimental constraints. In this study, we investigate an alternative configuration that uses three quadrupole magnets to form a negative identity transport section between the TDCs instead of a negative drift. To assess the robustness of this proposed design, a computational study has been conducted on initial beam conditions to determine the operational limitations. This includes the effects of space charge and initial transverse beam conditions, such as beam size and divergence, on the resulting transverse emittance.

Speaker: Alex DeSimone (Northern Illinois University)

15:10 Multi–objective Bayesian optimization of an electron injector linac for 4th generation light sources: A comparative Study with MOG

The performance of electron injector linear accelerators (linacs) critically influences the beam brightness and stability in 4th generation light sources. In this study, we employ a multi-objective Bayesian optimization (MOBO) framework to optimize the injector linac design, targeting the simultaneous minimization of transverse emittances and energy spread at the linac exit. This data-efficient approach leverages Gaussian process regression and acquisition functions to navigate the high-dimensional design space with significantly fewer simulations than conventional methods. We compare the results of MOBO with those obtained from the well-established Multi-Objective Genetic Algorithm (MOGA), highlighting differences in convergence speed, solution diversity, and computational efficiency. Our findings demonstrate that MOBO achieves comparable or superior optimization outcomes with reduced computational cost, offering a powerful alternative for accelerator design and tuning in next-generation light source facilities.

Speaker: Chong Shik Park (Korea University Sejong Campus)

15:30 → 16:00 Coffee

15:45 → 18:20 BeamNet (Parallel #2)

16:00 → 16:30 Exhibitor Presentations: Parallel #1

16:00 MICROWAVE TECHNIQUES LLC (Brian Blackwell)
16:05 Muons, Inc. (Dan Kaplan)
16:10 PRAB & APS (Frank Zimmermann)

16:00 → 18:00 Wednesday Poster Session

16:00 A compact top-off injection with cascaded nonlinear Kickers for diffraction limited storage rings

To address the intrinsic dynamic aperture (DA) limitations of fourth-generation diffraction-limited synchrotron light source, we investigate a novel injection scheme utilizing multiple nonlinear kickers (NLKs) with optimized hardware design and phase advances in the storage ring (SR). Positioning the NLKs near the injection point reduces beam perturbation, while their on-axis zero field and gradient enable transparent injection—suppressing orbit and beam-shape oscillations during top-off operations. Particle-tracking simulations were performed using Accelerator Toolbox (AT), alongside the development of automated tools for converting magnetic field maps into AT-compatible kick maps, inserting NLKs at arbitrary lattice locations, conducting tracking, and optimizing NLK configurations. A key challenge is to shift the off-axis magnetic field peak closer to the beam orbit. Our novel NLK design achieves a peak within 5 mm of the axis—a significant improvement over the conventional greater than 7 mm range. Simulations accounting for realistic alignment and magnetic field errors indicate that a relaxed 5 mm DA and injection efficiency > 90% could be feasible for the NSLS-II upgrade lattice.

Speaker: Xi Yang (National Synchrotron Light Source II)

16:00 A finite element study of stress reduction techniques in REBCO HTS conductor on a round cable (CORC) cable

ReBCO high-temperature superconducting (HTS) tape is critical for achieving the high magnetic fields needed in next-generation particle accelerators. Enhancing the mechanical performance of ReBCO tape increases its critical current by reducing internal stress, especially in the superconducting layer. A finite element study examined how copper layer properties affect stress in ReBCO conductor on a round core (CORC) cables. The cable was modeled as a doubly supported beam under uniform compressive stresses."cable was modeled as a doubly supported beam under uniform load to simulate bending. A staged modeling approach—from a single tape to a six-layer stack—enabled validation and efficient parameter studies. Increasing the yield strength and Young’s modulus of the copper layers reduced peak stress in the ReBCO layer. These results support development of improved tape stacks for high-field accelerator magnets

Speaker: Scott Mueller (Fermi National Accelerator Laboratory)

16:00 A new route to improve the material quality of Nb3Sn SRF cavities with Zr inclusion

Superconducting radio frequency (SRF) cavities based on Nb$_3$Sn superconductor can exceed the performance of conventional Niobium SRF cavities and would open many new industrial applications for small scale accelerators. The material quality-especially the surface non-homogeneity and microstructural defects, is the crucial challenge to realize the full potential of Nb$_3$Sn SRF cavities. In this work, we present our recently developed route for effectively reducing the intrinsic defects in magnetron sputter coated Nb$_3$Sn SRF cavities and eventually improve the overall RF performance.
In our study, we introduced a small variable fraction of Zr in Nb$_3$Sn host matrix using co-sputtering process. Post-annealing, the elemental Zr forms ZrO$_2$ precipitates of average dimensions ranging from 20-100 nm. We noted that the density of the surface and bulk voids as well as their average sizes are dramatically reduced on increasing the Zr content in Nb3Sn. We also observed that increasing Zr concentration up to an optimal level can substantially improve both superconducting transition temperature and upper critical magnetic field. Additionally, increasing the Zr concentration is also noticed to prevent the oxygen diffusion and resulting to a thinner formation of primary surface oxides. These results indicate that inclusion of Zr in Nb$_3$Sn sputtered coating will be a promising method to improve the material quality and might help to reduce the overall RF power dissipation.

Speaker: Malvika Tripathi (Fermi National Accelerator Laboratory)

16:00 A simulation of the Fermilab Main Injector dual power amplifier cavities

The Fermilab Main Injector accelerating cavities have sparking issues when they are run at voltages higher than those required by the PIP-II project. This is a problem Fermilab is working on as planning begins for the next upgrade to the accelerator complex. One of the methods being used to address the issue is the development of a CST Microwave Studio simulation to accurately model the PIP-II dual power amplifier cavities and identify which part(s) of the cavity is causing sparking to develop. The model will also be used to determine if changes to the cavity geometry may allow the cavity to be used at higher voltages before sparking occurs.

Speaker: Susanna Stevenson (Fermi National Accelerator Laboratory)

16:00 A W-band corrugated waveguide for high-efficiency high-gradient wakefield acceleration

Compact RF structures in the sub-terahertz regime are promising for structure wakefield acceleration due to their ability in achieving high gradients in a reduced footprint. We report on the design, fabrication, and testing of a metallic corrugated waveguide operating at 110 GHz, tailored to the 42 MeV electron beam parameters at the Argonne Wakefield Accelerator (AWA). The experiment utilized the emittance exchange (EEX) beamline at AWA for longitudinal bunch shaping in two configurations: (1) a single short drive bunch to study high decelerating gradients, and (2) a two-bunch scheme featuring a triangularly shaped drive bunch followed by a long witness bunch to probe the wakefield and achieve a high transformer ratio. We will present the experimental design and results, which show good agreement with simulation predictions.

Speaker: Brendan Leung (Northern Illinois University)

16:00 An Integrated Approach to Understanding Electric Breakdown

Our approach to the physics of vacuum arcs, which limits many technologies, has been to model rf breakdown in vacuum in four stages (trigger, ionization, evolution and damage), then generalize the model, filling in details with data from other fields, such as accelerator design, power transmission grid limits, large tokamaks, sample failures in atom probe tomography and thin film sputter coating systems. The immediate goal is to understand surface damage and the probability of future breakdown events. We have found that thermal contraction of the cold surface and surface tension flattening can explain clusters of crack junctions giving field enhancements on the order of 200 on otherwise inactive cold surfaces. We also find a combination of surface tension and Maxwell stress during arc evolution can produce an unstable liquid surface at high electric fields that explains the time structure of the arc and many aspects of surface damage seen in breakdown data. We describe the mechanisms, existing data and experiments which should be useful for refining models and producing a self consistent, widely applicable model of gradient limits.

Speaker: Jim Norem (Argonne National Laboratory)

16:00 Analysis of vapor diffusion Nb3Sn coating at Fermilab: Minimizing impurities using TOF-SIMS

Nb$_3$Sn demonstrates steady advancements nowadays offering reduced power cost in superconducting radio-frequency cavities due to its high critical temperature, quality factor, and achieved accelerating gradient. However, theoretical estimates of its radio-frequency parameters have not been achieved due to several potentially limiting mechanisms: tin spots, patchy regions, defects, thermal impedance, and impurities. While some of these limitations have been intensively studied, impurity analysis in Nb$_3$Sn coatings have received less attention. We report an investigation of impurities in several vapor-diffused Nb$_3$Sn coated samples using time-of-flight secondary ion mass spectroscopy (TOF-SIMS) and show allowable impurity levels in view of superconducting cavity performance. Challenges and lessons learned in maintaining clean Nb$_3$Sn coatings are also discussed.

Speaker: Nikki Tagdulang (Fermi National Accelerator Laboratory)

16:00 Application of low-cost sensors and deep autoencoders for monitoring water pumps in particle accelerators

In particle accelerator facilities, cooling-water pumps play a critical role in removing substantial amounts (in megawatts) of waste heat from numerous high-power accelerator components (e.g., magnets, radio frequency structures, power supplies) and beamline components. Despite their role in daily operations, inspecting hundreds of water pumps is labor-intensive and performed only occasionally. Their unexpected failures can potentially lead to degradation of beam quality, hardware damage, and costly unplanned downtime.
This study introduces an innovative method for real-time monitoring of water pump vibrations to identify anomalies that signal potential mechanical failures. Our approach integrates (i) low-cost vibration sensors, which will consistently sample pump vibration data and transmit it to a (ii) Deep Autoencoder** model for detecting anomalies. The autoencoder model recognizes each pump's normal pump vibration patterns and identifies subtle deviations. This monitoring framework can facilitate proactive maintenance by enabling early detection of anomalies, enhancing pump reliability, lowering maintenance expenses, and minimizing costly downtimes.

Speaker: Rajat Sainju (Argonne National Laboratory)

16:00 Baking of the vacuum chamber and Activation of the inside NEG coating film in the storage ring arc zone of HEPS

Due to the spatial constraints of the small-aperture magnets in the storage ring arc zone of the High Energy Photon Source (HEPS), where the magnetic pole gap is 26 mm and the vacuum chamber outer diameter is 24 mm, it is necessary to bake the vacuum chamber within a unilateral clearance of only 1 mm for the vacuum chamber degassing and NEG-coated film activation. This work introduces the online baking and activation scheme for the vacuum chamber in the storage ring arc zone of HEPS, including the design of the vacuum chamber heating method and the baking-activation procedures. Additionally, it records the changes in vacuum pressure and the variation in partial pressures of residual gases during the baking-activation process. After the baking-activation of the entire 48 arc zones were completed, the static vacuum pressure measured at the two gauge sites of the standard arc zones were, on average, 1×10−8 Pa and 5×10−8 Pa respectively across the whole ring. Compared with the simulation results after sufficient beam dose sweeping, the measured vacuum pressure is still nearly one order of magnitude higher.

Speaker: Ping He (Institute of High Energy Physics)

16:00 Booster cavity damper redesign for PIP-II

A new Higher Order Mode (HOM) damper was designed and is undergoing testing for the Booster accelerator cavity at Fermilab. In anticipation of the PIP-II upgrade, it was discovered that the higher intensity of PIP-II may cause beam instability due to an excited mode at 106 MHz. This unfortunately corresponds with the cavity’s 2nd order harmonic mode, which will sweep from 86-105.7 MHz. The new damper is a modification of an existing damper that was designed to reduce an existing static HOM at 83 MHz, with the new design intending to cover the 2nd order HOM as well. The existing damper uses an inductive coupling loop to extract RF energy from the cavity which then goes through a filter in order to reflect the fundamental frequency back into the cavity while passing HOMs to a dump load. The new damper intends to replace the filter portion of the system with a wider band variant while also changing the topology from a coaxial cable loop filter to a componentized PCB-based design. Primary design challenges include bandwidth coverage, impedance matching of the various modes, long term thermal and mechanical stability, radiation hardness, and high voltage handling. Initial designs achieved the desired damping but were found to quickly succumb to destructive arcing due to the voltages present. More finalized designs intend to address this problem through circuit design modifications as well as the use of hardier components.

Speaker: Dustin Pieper (Fermi National Accelerator Laboratory)

16:00 Centrifugal Barrel Polishing of a 650 MHz Single-Cell Niobium SRF Cavity

This work reports the first application of centrifugal barrel polishing (CBP) to a 650 MHz single-cell niobium superconducting radio frequency cavity. The CBP was performed using a newly installed large tumbler designed to accommodate four large-sized 650 MHz multi-cell cavities. The CBP process was applied to reset the cavity’s internal rough surface prior to electropolishing (EP). The study presents results on the surface condition and SRF performance following the CBP and subsequent standard cavity surface processing.

Speaker: Vijay Chouhan (Fermi National Accelerator Laboratory)

16:00 Co-sputter deposition of Nb₃Sn layer into SRF cavity using Nb-Sn composite target

Nb₃Sn, with its superior superconducting critical temperature (Tc ~18.3 K) and superheating field (Hsh ~400 mT), is considered a promising material for superconducting radiofrequency (SRF) cavities, offering enhanced cryogenic performance compared to bulk niobium cavities. A Nb₃Sn coating technique has been developed for Nb SRF cavities using co-sputtering of Nb-Sn composite target in a DC cylindrical magnetron sputtering system. The composite target configuration and discharge conditions for co-sputtering were optimized to deposit Nb-Sn films on flat Nb substrates, followed by annealing to form Nb₃Sn. Multiple strategies have been explored to improve the surface homogeneity of the Nb₃Sn coating, including optimizing a two-step annealing process, annealing in Sn vapor, and a light Sn recoating process. A 1.5 µm Nb-Sn co-sputtered film was deposited on the interior of a 2.6 GHz Nb SRF cavity and annealed at 600 °C for 6 h, followed by 950 °C for 1 h. Cryogenic RF testing of the annealed cavity demonstrated a Tc of 17.8 K, confirming the formation of Nb₃Sn. Then, the annealed cavity underwent a light recoating treatment and attained a quality factor (Q0) of 8.5E+08 at 2.0 K.

Speaker: Md Sharifuzzaman Shakel (Old Dominion University)

16:00 Collider-quality electron bunches from an all-optical plasma photoinjector

In recent years, plasma accelerators have advanced significantly toward producing beams suitable for colliders, aiming to replace conventional MV/m RF fields with GV/m fields of nonlinear plasma waves. Realizing a plasma-based collider requires electron bunches with high charge (hundreds of pC), low normalized emittance (~100 nm), and energy spread below 1%. Minimizing energy spread during acceleration involves flattening the accelerating field, which is achievable with a trapezoidal charge distribution.
We present a plasma photoinjector concept that enables collider-quality electron bunch generation using two-color ionization injection. The spatiotemporal control over the ionizing laser creates a moving ionization front inside a nonlinear plasma wave, generating an electron bunch with a current profile that flattens the accelerating field. Particle-in-cell (PIC) simulations of the ionization stage show the formation of an electron bunch with 220 pC charge and low emittance ($\epsilon_x = 171$ nm-rad, $\epsilon_y = 76$ nm-rad). Quasistatic PIC simulations of the acceleration stage show that this bunch is efficiently accelerated to 20 GeV over 2-meters with an energy spread below 1% and emittances of $\epsilon_x = 177$ nm-rad and $\epsilon_y = 82$ nm-rad. This high-quality electron bunch meets Snowmass collider requirements and establishes the feasibility of plasma photoinjectors for future collider applications.

Speaker: Arohi Jain (Stony Brook University)

16:00 Compact electron buncher with tunable permanent magnet focusing

We present a compact electron buncher that uses a permanent magnet setup for beam focusing. The buncher modulates the input direct-current beam into 5.7-GHz bunch train. The buncher consists of two radiofrequency (RF) cavities. Immediately downstream of each RF cavity, there is an electrostatic potential depression (EPD) section. An EPD section in an electrically insulated beam pipe biased with a negative high voltage. The EPD method remarkably shortens the buncher structure by rapidly forming the bunch train. Each of the RF cavities and the EPD sections uses an individual set of rectangular permanent magnets, arranged in a circular array, which provide a solenoid-like focusing field. The polarity of the magnets is configured to form an alternating on-axis magnetic field orientation for minimizing the total weight. Coarse adjustment of the magnetic field is achieved by adding or removing permanent magnet rectangles. For fine adjustments, the rectangles are moved evenly in the radial direction. We show simulation results of the buncher performance and the tunable magnetic focusing. Initial experimental results are also reported.

Speaker: Kevin Shipman (Los Alamos National Laboratory)

16:00 Consideration of HTS rapid-cycling magnet for staged muon acceleration

The HTS conductor hysteresis dominates magnet cable power loss but is independent of the magnetic field ramping rate. This makes the HTS conductor suitable to power the rapid-cycling accelerator magnet. We present a possible application of the HTS rapid-cycling magnet as outlined in [1,2] for the staged muon acceleration including the front-end Recirculating Linear Accelerator and the followed-up Rapid Cycling Synchrotrons delivering the muon beams to the Muon Collider.
[1] H. Piekarz, S. Otten, A. Kario, H. ten Kate, “Rapid-cycling HTS magnet for muon acceleration”, US MC Inaugural Meeting, FERMILAB-POSTER-24-0219-AD, August 7-9, 2024
[2] H. Piekarz, B. Claypool, S. Hays, M. Kufer, V. Shiltsev, “Record High Ramping Rates in HTS Based Supercond. Accelerator Magnet”, MT 27, IEEE Trans. on Applied Superccond, 32 (2022) 6, 4100404

Speaker: Henryk Piekarz (Fermi National Accelerator Laboratory)

16:00 Demonstration of a sheet electron beam production from a UNCD field emitter array

Ultra nanocrystalline diamond (UNCD) is a promising material for field emitters because of its mechanical and chemical stability, high thermal conductivity, and low electrical resistivity. We proposed to demonstrate fabrication of a special shape field emitter array to produce a sheet electron beam for high frequency vacuum tubes. At Los Alamos, we established a Field Emitter Array Test Stand (FEATS) where we can apply voltages up to 40 kV to test field emitter arrays in a vacuum level of 10^-7 Torr or lower. At this test stand, we can take beam images, measure beam current and study beam divergence. We fabricated diamond cathodes in form of arrays of 1 by 81 pyramids and used them to demonstrate production of a sheet electron beam. This talk will present details of the emission tests and analyses of the produced sheet beam.

Speaker: Wonjin Choi (Los Alamos National Laboratory)

16:00 Design and cold test of a novel waveguide power splitter for distributed power coupling in short-pulse acceleration

RF breakdown is the major limitation to achieving higher accelerating gradients. Recent experimental evidence shows that this limitation can be mitigated by reducing the RF pulse length to a few nanoseconds. One key challenge in designing an accelerator operating in the short-pulse regime is achieving the required short filling time. In this work, we designed a novel waveguide power splitter to independently feed an array of accelerating cells. A prototype X-band waveguide array for a one-to-four power splitter has been developed to drive standing-wave cavities operating in the short-pulse regime. The power is designed to be equally split and fed into four cavities, with the desired phase advance per cavity. A 3D-printed prototype has been used for low-power microwave measurements ("cold" tests). The results, including measurements with a vector network analyzer and time-domain measurements, show good agreement with simulations. Ongoing work includes designing a multi-cell accelerator based on this concept for two-beam acceleration with few-nanosecond RF pulses.

Speaker: Salih Colmekci (Northern Illinois University, Argonne National Laboratory)

16:00 Design guidelines and longitudinal dynamics for plasma-based, extreme compression

High-brightness, ultra-high peak current electron beams are of great interest for a range of applications, including high-energy colliders, strong field quantum electrodynamics, and laboratory astrophysics. However, the task of compressing electron beams to attosecond pulse durations and mega-amp peak currents while maintaining beam quality continues to pose a significant challenge. We explore, with start-to-end simulations, the feasibility of using plasma-based compression to generate ultra-short, high-peak current electron beams. By taking advantage of the large longitudinal electric fields present in a plasma wakefield, we demonstrate that large chirps can be imparted onto an electron beam, allowing it to be compressed to ultrashort durations in a magnetic chicane. We investigate the viability and limitations of this technique, and establish how the compressed beam properties depend on both accelerator and plasma parameters. Using these relationships, we find the optimal beam and plasma conditions for different applications, looking towards demonstrating plasma-based compression at the FACET-II facility at SLAC National Accelerator Laboratory.

Speaker: Kelly Swanson (SLAC National Accelerator Laboratory)

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 a low-power proof-of-concept multi-stage amplifier test stand to model and implement outphasing control for the LANSCE 805 MHz solid-state high-power RF amplifier

Los Alamos Neutron Science Center (LANSCE) has a project to investigate the feasibility for a replacement radio-frequency (RF) amplifier that is not reliant on vacuum electron tubes, has a similar footprint, and equivalent RF functionality. Gallium Nitride (GaN) on Silicon Carbide (SiC) high electron mobility transistors (HEMT) will be used in combined configuration. To maintain existing operational capabilities with these GaN amplifiers, the low-level control system needs to be modified for maximum transistor lifetime. The HEMT operates in a saturated condition, with a constant amplitude drive signal to avoid the high-power dissipation of linear operation with reduced drive. This leaves the phase of the RF inputs as a control mechanism, utilizing outphasing for amplitude modulation of the multistage amplifier. The GaN amplifiers also require a bias sequencing/protection board that is being designed and tested separately. To test and verify the control system, a low power test rack using commercial wideband RF components was built. This model system includes drive control, four 10 W amplifier stages, a final combination chassis, and accelerator timing system. The information from this test rack will be used to learn how to efficiently control a multistage high-power GaN amplifier to fit the requirements of the LANSCE linear accelerator.

Speaker: Michael Brown (Los Alamos National Laboratory)

16:00 Design of a shipping fixture for a compact cryomodule hermetic assembly

In support of the development of a conduction-cooled 915MHz superconducting radio frequency (SRF) cryomodule, this study highlights the design of a shipping fixture for transporting the hermetic assembly 4500 km from Jefferson Lab to General Atomics in San Diego, California. The hermetic assembly consists of a 2-cell 915 MHz SRF cavity, a coaxial fundamental power coupler and warm-to-cold transition beam tubes. The two-part shipping assembly consists of an inner frame, providing direct mounting of the components, and an outer frame mounted to the ground transport vehicle. The inner frame is then connected to the outer frame by way of wire-rope isolators. Accelerometer data from ground transportation of previous projects at Jefferson Lab provides the baseline for the expected frequency and magnitude of vibrational and shock events during transit. Modal analyses were carried out in ANSYS on the inner frame assembly and critical components to identify an appropriate wire-rope isolator configuration such that peak loads are mitigated and the incurred frequencies do not correspond with the fundamental modes of the structures.

Speaker: Jacob Lewis (Old Dominion University)

16:00 Design of an optical amplifier for amplified OSC in IOTA facility at Fermilab

Optical stochastic cooling (OSC) is a cutting-edge beam cooling technology to reduce, control the 3 dimensional spread and the motion of particle beams. It has recently been successfully, experimentally, demonstrated in Fermilab's IOTA storage ring, marking a major step forward in beam cooling. OSC has the potential to significantly improve both the performance and flexibility as a beam cooling system. One promising way to boost OSC performance is by adding a high-gain optical amplifier. However, this amplifier must be carefully designed to meet the specific constraints of the OSC system. A major challenge lies in the limited optical delay, which is just 6 mm for the case of IOTA, set by the beam bypass, restricts us to use a short-length gain medium. This, along with IOTA’s high repetition rate and the relatively long duration of the optical pulses, limits the peak power available for the pump laser without damaging the crystal, which is crucial for achieving strong nonlinear gain. Additionally, it's essential to preserve the phase coherence of the undulator radiation during amplification, which further complicates the amplifier design. This report details a specialized amplifier setup that addresses these challenges, includes simulations of the integrated system, and summarizes the latest experimental progress and results.

Speaker: Abhishek Mondal (Fermi National Accelerator Laboratory)

16:00 Design study of an RF-Kicker module for bunch cleaning at the ATLAS Positive-Ion Injector

Positive-Ion Injector at ATLAS accelerator facility can accelerate heavy ions and has three key subsystems -- an electron cyclotron resonance (ECR) ion source, a 12-MHz multi-stage beam bunching system, and a 12-MV superconducting linac accelerator. The first stage of the bunching system is a multi-harmonic buncher that operates at 12.125 MHz and creates a bunch train with a period of 82.5 ns at ~70% bunching efficiency. The remaining unbunched beam must be removed to avoid the production of undesirable ‘satellite’ bunches, which can quench the superconducting solenoids downstream during operation. In this paper, we present the design of a resonant sine-wave RF-structure that effectively removes the bunch ‘tails’ using a vertically deflecting kick. We also discuss the effects of the RF-Kicker on the beam quality, which was estimated by TRACK3D simulations.

Speaker: Deeksha Sinha (Northern Illinois University)

16:00 Design study of novel deuteron cyclotron auto-resonance accelerator

A novel 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. Such an accelerated beam can be used to produce the intense neutron flux via breakup of deuterons on a low-Z target. It is estimated that 5-10 small dCARA-based modules could provide the same level of transmutation as one acceleration driven system (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 (Omega-P R&D, Inc., Particle Accelerator Research Foundation)

16:00 Developing a Hybrid Accelerating Structure Based on Short-Pulse Structure Wakefield Acceleration

Structure Wakefield Acceleration (SWFA) powered by -short RF pulses (~10 ns) generated by Two-Beam Acceleration (TBA) at the Argonne Wakefield Accelerator (AWA) has demonstrated effective suppression of RF breakdowns and achieved gradients exceeding 400 MV/m at X-band (11.7 GHz) frequencies. To fully exploit the benefits of this short RF pulse operation, an accelerating structure must simultaneously achieve two goals: high group velocity (Vg) to ensure rapid RF filling (need for high efficiency), and simultaneously maintain high shunt impedance (R) (need for high accelerating gradient). Conventional accelerating structures involve inherent tradeoffs between these parameters, limiting their effectiveness in the short-pulse regime. To this end, we developed a hybrid structure composed of two co-optimized sub-structures fed by one coupler at the middle: one backward wave (BW) filling and one forward wave (FW) filling sub-sections.This design not only preserves the short-pulse advantage, it also simplifies the setup (one input coupler for two structures) and enhances the beam’s energy gain by doubling the acceleration length without requiring extended RF pulse duration. In this work, we present the detailed RF design with preliminary beam dynamics simulations demonstrating efficient energy gain within a compact acceleration length.

Speaker: Gongxiaohui Chen (Argonne National Laboratory)

16:00 Development and fabrication of CW copper injector for SRF industrial cryomodules

Compact SRF industrial linacs can provide unique parameters of the beam (>1 MW and >1-10 MeV) hardly achievable by normal conducting linacs within limited space. SRF technology was prohibitively expensive until the development of conduction cooling which opened the way for compact stand alone SRF systems suitable for industrial and research applications. Limited cooling capacity puts strict requirements on the beam parameters with zero losses of the beam on the SRF cavity walls. This implies strict requirements on the beam energy to be accepted by the cryomodule and most importantly the beam bunching with zero particles in between.
We designed a CW normal conducting RF injector which consists of a gridded RF gun integrated with a first cell of a copper booster cavity to satisfy these requirements. Here we present a finalized as well as the fabrication status of the injector.

Speaker: Chunguang Jing (Euclid Techlabs (United States))

16:00 Development of combined function Dipole-Quadrupole PMQs magnets for NSLS-II upgrade

This paper focuses on the R&D performed for the development of permanent magnets-based dipoles-quadrupoles combined function magnets (PMQs) for the future NSLSII upgrade “complex bend” lattice (CB). This new lattice uses PMQs that provide both bending (dipole) and strong focusing (quadrupole) magnetic field on the electron beam. The permanent magnet (PM) technology is suitable for the high magnetic field strengths (0.5 T, 130 T/m) required for such combine function magnets. PM technology leads to a compact magnet design that is essential in realizing the complex bend lattice concept, as well as a passive magnet solution which does not require electrical power supply reducing power consumption by ~ 80% (from 1.7 MW to 0.3 MW for NSLS-II). Two PMQs magnets designs are under consideration: A hybrid design that use both PM and soft iron poles, and Halbach type that is a pure PM design. Both PMQs designs present challenges in achieving the specified magnetic field quality due to their higher sensitivity to errors (mechanical tolerances and PM properties). This paper presents cost-effective designs and prototypes results for hybrid and Halbach PMQs, addressing various technical challenges while meeting the field requirements of the complex bend lattice for the NSLS-II upgrade.

Speaker: Patrick N'gotta (Brookhaven National Laboratory)

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: Mohamed Othman (SLAC National Accelerator Laboratory)

16:00 Developments in LUME-ACE3P including S-parameter optimization for S3P

We present here the introduction of optimization to LUME-ACE3P (LUME: Lightsource Unified Modeling Environment; ACE3P: Advanced Computational Electromagnetics 3D Parallel). LUME-ACE3P is a Python wrapper that streamlines workflows for ACE3P, a suite of finite element solvers for electromagnetic fields in complex geometries. LUME-ACE3P offers parameter sweep capabilities, which was previously the only means to perform optimization with this code. In the integration of LUME-ACE3P with the optimization package Xopt, we facilitate efficient and easy to use optimization for accelerator component design. We present the LUME-ACE3P-Xopt workflow with an example problem.

Speaker: Lila Fowler (SLAC National Accelerator Laboratory)

16:00 Efficient continuous-wave normal conducting accelerator for industrial applications

A normal conducting, high power, high efficiency copper linear accelerator prototype is being developed for industrial applications. The system will be powered by low-cost high-efficiency magnetron RF sources and will use a gridded thermionic cathode electron gun. Leveraging the significant accelerator expertise at JLab and industry partners, these technologies will be combined to deliver high-power (>100 kW) electron beams with energies of 1 MeV or higher that are cost-effective to produce and operate. The design is modular such that energy and power can be increased by adding additional sections as required. The status of the design, prototype fabrication and plans for a beam demonstration at JLab are described.

Speaker: Robert Rimmer (Thomas Jefferson National Accelerator Facility)

16:00 Elimination of Training in Nb3Sn and NbTi Superconducting Magnets

By using TELENE® resin as superconducting magnet impregnation material, training and magnet retraining after a thermal cycle were nearly eliminated in Nb3Sn undulators. This allows reducing operation margins in light sources, and increasing the on-axis magnetic field, thereby expanding energy range and brightness intensity. TELENE is Co-60 gamma radiation resistant up to 7-8 MGy, and therefore already applicable to impregnate planar, helical and universal devices operating in lower radiation environments than high energy colliders. Radiation resistance further increases in TELENE when mixed with high-Cp and/or high-thermal conductivity powders. We herein show that when combined with the ductility and toughness properties of TELENE, these resins display superior training performance with respect to CTD-101K in a variety of Nb3Sn magnet models. In addition, TELENE was proven to eliminate training also in NbTi accelerator magnets. Therefore, TELENE can be used in the Magnetic Resonance Imaging (MRI) industry to solve the NbTi solenoids training problem. The transfer of technology in using TELENE resin to the MRI industry will have transformative societal impact on global health.

Speaker: Emanuela Barzi (The Ohio State University)

16:00 Experimental generation of petawatt peak power, extreme electron beams for advanced accelerator applications

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 at the FACET-II National User Facility at SLAC National Accelerator Laboratory. 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 high-field plasma wakefield acceleration to laboratory astrophysics and strong field quantum electrodynamics. We demonstrate our ability to generate and control the properties of these electron beams by means of a laser-electron beam shaping technique. 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 including optimization of advanced accelerator applications.

Speaker: Claudio Emma (SLAC National Accelerator Laboratory)

16:00 Experimental Progress of PWFA in a Laser-Ionized Plasma Source FACET-II

To compete with conventional accelerators, collider and light source applications based on plasma wakefield acceleration need to be able to handle 10s of Joules of energy transfer between the drive beam, plasma, and witness beam at repetition rates exceeding 100 Hz. Scaling up to these parameters is challenging due to the large amount of heat deposited in the plasma source. To begin approaching this regime, we developed a laser ionized plasma source using a pair of diffractive optics to produce a meter-scale Bessel focus with a tailored axial intensity profile. Using this source, we demonstrate multi-Joule energy transfer in the plasma accelerator at SLAC’s FACET-II facility with strong deceleration of the drive bunch and acceleration of a witness bunch.

Speaker: Michael Litos (University of Colorado Boulder)

16:00 External controller for the SRFK thyratron heaters

The following work will detail the development and implementation of a system which will measure the voltage and current from two points on a high-voltage switch called a thyratron and automatically manipulate two variable transformers controlling these values. Each of the extraction kickers at LANSCE (SRFK71 & SRFK81) uses a thyratron to trigger their respective pulses. The thyratrons have separate heaters for the cathode and reservoir, and each needs to maintain specific voltage and current levels for the thyratron to work properly. Currently, the method of measuring and adjusting these values requires locking out the system, opening the tank, and measuring the voltage and current of each heater, then adjusting two variable transformers by hand to reach the desired values. This controller consists of four analog-to-digital converters which will relay these measurements out of the modulator as digital signals through fiber optic transceivers. An Arduino will be programmed to interpret the digital signals and display the values on an LCD. It will also return signals to DC motors controlling the variable transformers if the values lie beyond the desired range.

Speaker: Benjamin Laurel (Los Alamos National Laboratory)

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 Final design and first use of in-situ measuring apparatus for measurement of permanent magnet resiliency in CEBAF’s radiation environment

In this work we outline the final design and initial measurement lessons for the holders and measuring apparatus of the permanent magnet resiliency experiment which is a part of the FFA@CEBAF proposed upgrade. The experiment will expose permanent magnets to the radiation environment of CEBAF. Due to safety regulations we need to measure the magnets in the tunnel without bringing them out, so we designed a mobile measuring system as well as a series of protocols to allow us to speedily measure these samples even under adverse conditions. We also designed our system to be capable of taking measurements even with component failures.

Speaker: Edith Nissen (Thomas Jefferson National Accelerator Facility)

16:00 First results from a Nb3Sn-coated 1.5-cell 650 MHz SRF cavity for cryogen-free industrial accelerators

Fermilab is advancing the development of a compact, high-power electron beam accelerator using superconducting radio frequency (SRF) technology as a non-radioactive alternative to traditional radiological sources. The current design targets continuous-wave (CW) operation at 1.6 MeV and 20 kW. To ensure suitability for industrial environments, the system is being designed for cryogen-free operation, driving the adoption of a novel Nb₃Sn-coated 1.5-cell SRF cavity operating at 650 MHz.
This contribution reports on the fabrication, surface preparation, and Nb₃Sn coating process of the cavity, as well as first results from vertical test stand (VTS) measurements performed in a liquid helium bath. These initial tests mark a key milestone toward demonstrating the viability of conduction-cooled Nb₃Sn SRF cavities for industrial-scale deployment.

Speaker: Nikki Tagdulang (Fermi National Accelerator Laboratory)

16:00 Fitness For Service Assessment of a Corroded Heat Exchanger

Fermilab’s Main Injector Accelerator has used shell & tube heat exchangers to cool various beamline components since its construction in the late 1990s. Many of the heat exchangers still around today are original to the machine. Untreated pond water has been used to exchange heat with the Low Conductivity Water. Throughout the lifetime of Fermilab’s heat exchangers, they have undergone significant material degradation in the carbon steel end channels due to corrosion. Wall thickness measurements (per API 510) of each heat exchanger were used to generate a 3D model of the corroded surfaces. In order to continue their safe and reliable operation, ASME FFS-1/API 579 (Fitness-For-Service) was implemented to address their integrity. The assessments consisted of finite element analysis techniques outlined in ASME Section VIII Div. 2 (design by analysis methods for pressure vessels), in accordance with the requirements of ASME FFS-1 Part 4: General Metal Loss, Part 5: Local Metal Loss, and Part 9: Crack Like Flaws. The assessments concluded that each heat exchanger is coined “Fit For Service”. The Fitness-For-Service standard offers a unique opportunity to facilities and institutions within the DOE National Lab complex to properly and safely assess the integrity of aging equipment necessary to conduct science and research. This poster demonstrates the assessment process and techniques used to determine the heat exchangers are fit for service.

Speaker: Alex Humenik (Fermi National Accelerator Laboratory)

16:00 Grid disturbance rejection via improved DC-Link voltage feedforward control for L-Bend power supplies in the APS upgrade

As part of the Advanced Photon Source Upgrade (APS-U), two high-power DC supplies for the L-Bend M1 and M2 magnets were installed. During the APS-U commissioning, a 1 Hz ripple was detected in the output currents of the M1/M2 and slow corrector supplies, leading to 1 Hz beam motion. This low-frequency harmonic originated from the booster ramping supply operating at 1 Hz, causing periodic grid voltage sags. This paper proposes an improved DC-Link voltage feedforward control for the M1/M2 supplies to reject grid disturbances, significantly attenuating the 1 Hz and other low-frequency ripples in the output currents. Combined with regulation circuit modification of the slow corrector power supplies, the 1 Hz harmonic was successfully eliminated from the beam motion.

Speakers: Fernando Rafael (Argonne National Laboratory), Yang Ruan (Argonne National Laboratory)

16:00 Ground vibration studies in the RHIC tunnel in view of EIC

As beam sizes get smaller at the collision point, the environment vibrations and their amplification through the accelerators supporting structures need more careful considerations. Indeed these mechanical disturbances can produce a beam orbit jitter that is detrimental to a collider operation, through loss of luminosity or increased beam-beam effects.
In preparation for EIC, measurements of the ground vibration environment in the RHIC tunnel were carried out. This paper will summarize the measurement methodology and present its main results. The expected effect on the hadron and electron beam jitter will be described and we will discuss some design consideration on the new electron ring magnet supports to mitigate this effect.

Speaker: Frederic Micolon (Brookhaven National Laboratory)

16:00 Heavy Ion implantation analysis in graphite for the FRIB charge selector

An advanced charge selector is currently under development at the Facility for Rare Isotope Beams (FRIB) to intercept unwanted charge states of stripped heavy ion beams. Rotating graphite wheels are employed to absorb beams with a power up to 5 kW and a size as small as an rms width of 0.7 mm × 1.25 mm.
The implantation of beam ions and accumulated radiation damage affect the material properties, potentially leading to its structural failure. Determining the foreign ion accumulation behavior is one critical aspect for predicting the operational lifetime of the graphite wheels. In this study, ion implantation distribution was first characterized using SRIM simulations, then coupled with Monte Carlo analysis to account for wheel geometry and rotational dynamics. The evolution of the ion concentration profiles was subsequently determined considering the diffusion effects. The analysis reveals that strategic beam positioning optimization, combined with diffusion effects, substantially reduces peak ion concentrations and implantation rates, providing essential data for graphite wheel lifetime assessment.

Speaker: Alexander Plastun (Facility for Rare Isotope Beams)

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 805 MHz solid state amplifiers using GaN on SiC HEMT for LANSCE CCL

The Los Alamos Neutron Science Center uses a coupled-cavity linac (CCL) to accelerate H- ions from 100 to 800 MeV. It is powered by forty-four 1.25 MW 805 MHz klystrons of older design. Continued supplies of identical klystrons for the linac operation beyond 2050 are uncertain. We have embarked on a feasibility study for a replacement RF amplifier without vacuum electron tubes, that fits in the space of one klystron. Commercial silicon LDMOS transistors have reduced power above 600 MHz and are limited by the maximum drain to source breakdown voltage. We selected high voltage Gallium Nitride (GaN) on Silicon Carbide (SiC) high electron mobility transistors (HEMT) to reduce the number of active devices and the complexity of power combing smaller amplifiers. They are able to operate at higher channel temperature and voltage ratings compared to silicon transistors. We have tested devices with 3.6 kW of saturated power at 100 volts, and are planning for 5 kW HEMTs for the final design. Outphasing modulation schemes allow higher efficiency and lower thermal dissipation than class AB linear amplifiers. Power supplies and combining technology are also under study for this system.

Speaker: John Lyles (Los Alamos National Laboratory)

16:00 High-Voltage Pulsed Power Generator for Beam Injection Systems

Beam injection systems in hadron colliders require kickers generating ±50 kV peak voltages into a 50 Ω impedance, with peak currents of 1000 A and sub-10 ns rise and fall times. This paper presents a novel high-voltage pulse power generator utilizing a dis-tributed pulser architecture. It combines gallium nitride (GaN) transistors in a Marx to-pology with an inductive adder, achieving nanosecond-scale switching speeds and high-power efficiency. Compared to other solutions such as based on MOSFETs or fast ioniza-tion dynistors, our development offers superior peak and average power performance, reduced system complexity, and enhanced reliability, marking a significant step forward in high-voltage pulse generation for accelerator applications.

Speaker: Evgeniy Ivanov (RadiaBeam Technologies (United States))

16:00 Improvements to the LANSCE CCL klystron evaluation

This paper describes the existing procedure for LANSCE 805 MHz klystrons testing and evaluation and realized avenues for improvement. Each of the 1.25 MW klystrons used for powering LANSCE CCL (side Coupled Cavity Linac) are tested during first installation or fol-lowing a fault in operations. Executed testing process includes high potting, pulsing, and full power RF testing. Generated testing data is used for evaluation and certifi-cation of spare units for the linac. In this paper, we hope to breakdown this expert-dependent, lengthy 1–2 month process and examine improvements which can accelerate time to evaluation. The goal of this paper is to fully cap-ture the current procedures and investigate improvements to modernize our legacy systems and processes.

Speaker: Aditya Waghmare (Los Alamos National Laboratory)

16:00 Integral Field Probe for Mapping of Curved Magnets

The Single Stretched Wire (SSW) method allows highly precise integral field measurements by recording voltage across a tensioned wire mounted to 2-axis linear stages at either end of the magnet aperture. However, traditional SSW probes are not well suited for curved accelerator magnets, which are essential for steering charged particles along arced trajectories in storage rings or beamlines. The tension required to eliminate sag demands a purely straight path, making them incompatible with non-linear magnet geometries. To address this limitation for curved magnets, a modified approach was developed using a segmented, 3D-printed support structure that incorporates a pre-shaped “anti-sag” curve. Under its own weight and that of the wire bundle, the structure deforms to lie flat while conforming to the curvature of the magnet in the horizontal plane. The optimal geometry of the probe was derived using an iterative process combining FEA simulations in Ansys Mechanical with testing of various carbon fiber-reinforced filaments. The printed and assembled probe was successfully used to measure the SDD-055 magnet at Fermilab, yielding promising results.

Speaker: Alexander Jakopin (Northern Illinois University)

16:00 Investigating Dirac semimetal cadmium arsenide as a potential low-MTE photocathode

We report on the quantum efficiency (QE) and mean transverse energy (MTE) of photoemitted electrons from cadmium arsenide (Cd₃As₂), a three-dimensional Dirac semimetal (3D DSM) of interest for photocathode applications due to its unique electronic band structure, characterized by a 3D linear dispersion relation at the Fermi energy. Samples were synthesized at the National Renewable Energy Laboratory (NREL) and transferred under ultra-high vacuum to Arizona State University (ASU) for measurement using a photoemission electron microscope (PEEM). The maximum QE was measured to be 3.37 × 10^-4 at 230 nm, and the minimum MTE was 55.8 meV at 250 nm. These findings represent the first reported QE and MTE measurements of Cd₃As₂ and are an important step in evaluating the viability of 3D DSMs as low-MTE photocathodes. Such photocathodes, constrained to lower MTEs by the electronic band structure, may prove effective in advancing beam brightness in next-generation instruments and techniques.

Speaker: Truman Idso (Arizona State University)

16:00 Investigation of transverse instability in efficient plasma-based accelerators

Plasma-based accelerators offer a promising route to compact high-energy particle sources. However, recent theoretical work* has suggested that accelerating a low-energy-spread electron beam may not be feasible at high efficiency because of the excitation of transverse beam break up (BBU) instability. This instability, which leads to a growing spatio-temporal oscillations of the beam centroid, is a consequence of a significant misalignment or loss of symmetry between the beam and the accelerating structure (ion cavity) and arises because of the coupling between the accelerating beam electrons and the plasma sheath electrons surrounding the ion cavity. The instability deteriorates the electron beam parameters (notably, the beam emittance) and hinders the usefulness of the plasma-based accelerators for some potential applications like, particle colliders. Here, using particle-in-cell simulations and analytical modelling, we evaluate the centroid evolution of a partially misaligned trailing electron bunch coupled with a plasma accelerator and provide novel solutions for its suppression. We also present preparation status of an experiment designed to characterize the transverse instability on a well-defined externally injected electron beam from a conventional linac in a CO2 pulse driven LWFA at Accelerator Test Facility (ATF) at Brookhaven National Laboratory (BNL).

Speaker: Naveen Pathak (Stony Brook University)

16:00 Jefferson Lab’s multi-purpose modular FPGA based controller board improves on project design cycle

Embedded control design often requires extensive engineering time. Development boards, while useful, provide minimal peripherals for complex projects. A modular Field Programmable Gate Array (FPGA) controller printed circuit board (PCB) was designed which reduces concept to implementation time dramatically. A low cost flash embedded FPGA was chosen for this board which helped reduce components and complexity. A detailed specification and design choices for the controller board will be presented. Initially this controller was designed for a linear DC-DC power converter for trim magnet system. It was further realized that with available ADC and DAC channels, many I/O ports and available MODBUS, serial communication protocol that this board can be used for other applications. Such as, Jefferson Lab’s low noise supply (LNS) (100 parts per million (ppm) 20A DC power supply) and a controller for three 15kW power supplies each with motorized polarity switches. These applications make this controller an "all-in-one" design for low cost quick turnaround projects.

Speaker: Maxwell Roy (Thomas Jefferson National Accelerator Facility)

16:00 LANSCE CCL klystron high potting investigation and improvements

LANSCE uses 44 805MHz klystrons to power the Coupled Cavity Linac (CCL). Modulated anode tubes such as the 1.25 MW LANSCE klystrons need high volt-age testing and processing prior to full operation. This not only verifies the klystron can hold-of HV but also allows the klystron to process out some internal imperfections prior to being pulsed by the modulator for the accelerator. The LANSCE accelerator is a relatively long pulse machine, and improper processing can lead to premature degradation in the performance of the tube. This paper describes recent improvements to the 1.25MW 805MHz klystron HV check and conditioning process through the development of a new high-potting test stand. High-potting setup and techniques that were historically used are contrasted with the new implementation. Our goal is to improve LANSCE operations by accelerating the high-potting process and reducing expert time and dependence. The new test stand will optimize legacy processes by improving diagnostics, automating control and reducing inconsistencies and process invariability due to human factors. Analysis and automation efforts for this critical process are discussed along with current benefits and future work.

Speaker: Aditya Waghmare (Los Alamos National Laboratory)

16:00 Laser-Ionized Plasma Sources for Plasma Wakefield Accelerators: Alignment Technique, Tolerance, and Applications

Plasma wakefield accelerators (PWFA) are promising candidates for next-generation colliders due to their ability to sustain extremely high acceleration gradients. Laser-ionized plasma sources offer key advantages for PWFA, including precise control over the transverse and longitudinal plasma density profiles for emittance preservation, tunable plasma column widths suited for positron acceleration, and resilience to heat deposition. A critical experimental challenge, however, is the precise alignment of the plasma source to the electron beam and maintaining that alignment over time. We report on a novel alignment technique developed at the Facility for Advanced Accelerator Experimental Tests II (FACET-II), enabling high-precision alignment of a 1-meter-long laser-ionized plasma source to a 10 GeV, 1.6 nC electron beam with a transverse accuracy better than 10 µm, limited primarily by laser pointing jitter. We present our methodology, discuss the alignment tolerances between the drive beam and the laser-ionized plasma, and explore future opportunities for using narrow plasma columns for positron acceleration.

Speaker: Valentina Lee (University of Colorado Boulder)

16:00 Latest Progress on Plasma Wakefield Acceleration at FACET-II

Plasma Wakefield Acceleration (PWFA) can provide 10’s of GeV/m acceleration gradients, providing a novel path towards efficient and compact future colliders and high brightness free electron lasers. At the Facility for Advanced Accelerator Experimental Tests II (FACET-II) at SLAC, we are undertaking experiments in PWFA using a 10 GeV electron beam configured as a drive and witness pair. We will share our progress towards the ultimate goal of doubling the energy of the 10 GeV witness bunch by PWFA, with high efficiency and while preserving beam quality. Our latest results demonstrate multi-GeV acceleration of the witness bunch, with energy gains exceeding 5 GeV and sub-percent energy spread, using a 40 cm long lithium vapor plasma source. Additionally, we have achieved near-complete charge capture of the witness bunch and are actively working to minimize emittance growth through careful control of the transverse properties of the bunches.

Speaker: Douglas Storey (SLAC National Accelerator Laboratory)

16:00 Light-induced enhancement of quantum efficiency in III-Nitride photocathodes

" High quantum efficiency (QE) semiconductor photocathodes are essential for generating high average beam current and brightness. One class of semiconductor photocathodes considered for use in photoinjectors for unpolarized and polarized electron beams are III-nitride heterostructures. These materials can exhibit negative electron affinity at the surface, utilizing intrinsic polarization fields to engineer the band structure without the need for additional surface treatments. In this study, we investigate the effects of light exposure on the surface of III-nitride photocathodes and the resulting changes in QE and photoemission, using photoemission electron microscopy (PEEM) for characterization. We demonstrate that exposing a GaN photocathode to a 240 nm wavelength laser at 870 µW for 15 minutes increases the QE by two orders of magnitude, with a maximum QE of 2.34 × 10⁻⁴ observed. Although III-nitride photocathodes are known for their robustness, our findings indicate that laser exposure can significantly alter their QE. Our observations reveal the need for a detailed investigation of photo-induced effects on QE in III-Nitride photocathodes."

Speaker: Mansoure Moeini Rizi (Arizona State University)

16:00 LLRF commissioning of the CEBAF C75 upgrades SAM 2024/25

An often-overlooked aspect of Low Level Radio Frequency (LLRF) design is commissioning of a new system. During Jlab’s Scheduled Accelerator Maintenance (SAM) in 2024, two C75 Cryomodule were installed in CEBAF with Jlab’s LLRF 3.0 system. Jlab’s team has invested effort in automating and standardizing their commissioning process. Several key components are klystron characterization, cavity characterization, and interlock verification. This poster will present the summary of LLRF preparation and commissioning efforts at Jlab.

Speaker: Jayendrika Tiskumara (Thomas Jefferson National Accelerator Facility)

16:00 Low frequency ripple current attenuation for slow corrector power supplies in the APS Upgrade

As part of the Advanced Photon Source Upgrade (APS-U), approximately one thousand bipolar power supplies were installed to power the slow corrector magnets. During the APS-U commissioning, a 1Hz harmonic was detected in the beam motion. This harmonic originates from the 480V AC grid, caused by the booster ramping power supply operating at 1 Hz. The resulting grid disturbance introduced low-frequency ripples into both the corrector magnet power supplies and the L-Bend M1/M2 supplies, leading to the observed 1 Hz beam motion. This paper proposes two methods to mitigate these ripples in the corrector supplies: setpoint compensation using repetitive control, and regulation circuit adjustments through a simple jumper reconfiguration. The second approach was adopted and applied to all slow corrector magnet power supplies. Operational data showed that the low-frequency ripples were significantly attenuated in the corrector supplies, and in combination with fine-tuning of the L-Bend M1/M2 supplies, the 1 Hz beam motion was successfully eliminated.

Speaker: Yang Ruan (Argonne National Laboratory)

16:00 Magnetic field and force calculation of the new SCU prototypes

New 0.5m long SCU prototypes were designed based on lessons learned from the previous full length (1.5 m) core experiences. The original monolithic cores have all steel poles. The new cores have plastic back poles to avoid electrical shorts of superconducting wires to cores. Magnetostatic calculation was made for one period model for each of two designs under consideration. Then, magnetostatic, and mechanical analysis was also conducted for the prototype SCUs with the lengths of 29.5 and 23.5 periods. The software used for this simulation is ANSYS Maxwell and Mechanical. Both the magnetostatic and the mechanical analyses confirm the validity of the new design.

Speaker: Yuko Shiroyanagi (Argonne National Laboratory)

16:00 Modeling of plasma channels 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 Monte-Carlo modeling and experimental investigation of photoemission from CsTe semiconductor photocathode under high fields

Beam brightness can be enhanced with high gradient operation in photocathode guns. Such high gradient guns, such as the L-band gun at the Argonne Wakefield Accelerator (AWA) facility and the C-band high gradient gun being commissioned in the CARIE project at Los Alamos National Laboratory, are also typically equipped with semiconductor photocathodes due to their high quantum efficiency. To investigate the photoemission process in semiconductor thin-film photocathode under such conditions, we developed Monte-Carlo transport and photoemission models employing electronic, phonon, dielectric and optical properties directly from Density Functional Theory (DFT) calculation, as well as the photo excitation model based on the light interference effect in thin films. This photoemission model is further employed in photocathode gun simulation and used to investigate a recent high-gradient experiment conducted at the AWA photo injector. We will discuss the effects of the high field gradient on photoemission through a comparison of the measurement and the simulated beam dynamics.

Speaker: Chengkun Huang (Los Alamos National Laboratory)

16:00 NEG coating and thermal coating spray of vacuum chamber

As the fourth-generation synchrotron radiation light source, vacuum chambers with small apertures were employed for high energy photon source (HEPS), making the performance of Non-evaporable getter (NEG) coating is very crucial for its vacuum system. After years of development, the highly stability of the NEG coating has been achieved. Massive production facilities of NEG coated vacuum chambers have been developed for HEPS in Huairou, Beijing, which based on the NEG coating prototypes. The facilities can achieve simultaneous coating of 16~20 vacuum chambers of HEPS including irregular shaped vacuum chambers. The pumping performance of the NEG coated vacuum chambers has been measured by test facilities. After heated at 200°C for 24 hours, the highest pumping speed of H2 is about 0.65 l/scm2, and the highest capacity of CO is about 1.89×10-5 mbar·L/cm2. The lifetime is more than 20 cycles of air exposure and re-activation. Multilayer thermal coating spray have been studying and preliminary test shows that the heating temperature could reach 300 ℃, and after more than 12 times reheating, the spraying layer also shows a good adhesion.
The baking is the most crucial procedure in achieving ultra-high vacuum. Due to NEG coating reactivation and degassing, to meet the ultra-high vacuum requirement of achieving a dynamic vacuum level of ~10-10 mbar. Multilayer thermal coating will be coated outside of the vacuum chamber which composited by ceramic and conductivity layer, the heating temperature could reach 300℃.

Speaker: Ping He (Institute of High Energy Physics)

16:00 New development and testing facility for HPRF SSA system at LANSCE CCL

A new high-power RF test facility was developed at the Los Alamos Neutron Science Center (LANSCE) to evaluate components of a RF Solid-State Amplifier (SSA) system operating at 805 MHz and targeted for a final output power of 1.25 MW. The system is powered by a 100 V DC supply and stabilized with a 0.1 F capacitor bank to support transient power demands, capable of storing up to 1.125 kJ of energy. The SSA utilizes Gallium Nitride (GaN) on Silicon Carbide (SiC) high electron mobility transistors (HEMTs) and employs water cooling to manage thermal loads and ensure stable operation under high duty-factor pulsed conditions. Multiple HEMT amplifier modules will be power combined to achieve the full 1.25 MW output, with the aim of enhancing reliability, modularity, and maintainability in accelerator RF infrastructure. Integrated protection procedures allow for secure shutdown of RF drive and DC power in the event of overvoltage, overcurrent, or thermal excursions. This test configuration supports ongoing evaluation of solid-state amplifier performance, thermal handling, and integration with RF passive components under realistic operational conditions.

Speaker: Javier Vega (Los Alamos National Laboratory)

16:00 NSLSII RF-shielded bellows offset testing

The NSLSII storage ring contains over 180 RF shielded bellows over its 792 m circumference. Three of these bellows are instrumented with RTD temperature sensors on the internal components to monitor and validate expected performance. The temperature data showed an increasing internal temperature trend during successive 500mA beam operation on one of these bellows. This bellows and many other installed bellows throughout the ring, are near to or over the vertical and horizontal offset tolerance. Offsets can create an RF path between the sleeve and fingers, which raised concern there was degradation of performance resulting from the offset condition. The bellows was removed and inspected with some visual signs of discoloration and loose RTD anchor points were also observed. With the prospects of moving from 400mA to more permanent 500mA operation, a test was conducted to confirm internal temperatures were safe. Two fully instrumented bellows were remotely offset under steady beam operation while observing the internal temperatures. The bellows with offset geometry was also studied with GdfdL code. The experimental results will be presented and compared to the wake-potential calculations.

Speaker: Robert Todd (Brookhaven National Laboratory)

16:00 One-to-one mapping between the electromagnetic modes of cylindrical and coaxial half-wave cavities

Design of radio frequency (RF) couplers and diagnostics require a good understanding of the electromagnetic mode patterns of RF cavities. This study investigates the adiabatic transformation of transverse magnetic (TM) modes in a cylindrical cavity into transverse electromagnetic (TEM) modes of a coaxial cavity by gradually introducing an inner conductor. Using CST Studio Suite, we simulate the eigenmode evolution as the geometry transforms from a pure cylindrical to a coaxial configuration. We track the behavior of TM010 through TM014 modes to observe the continuous evolution into the corresponding TEM0 through TEM4 modes of the coaxial cavity. The process is governed by the evolution of the electric field orientation as the geometry shifts, enabling the axial TM fields to reorient into the radial electric field configuration of TEM modes. Field patterns, eigen-frequencies, and mode indentities are analyzed throughtout the transition. The results provide simulation-based evidence that TM to TEM conversion occurs without generation of newer eigenmodes, offering a valuable insight into the design of transition regions in superconducting RF (SRF) systems and provides a foundation for experimental validation.

Speaker: Fariha Ahmed (Old Dominion University, Thomas Jefferson National Accelerator Facility)

16:00 Overview of the FACET-II facility at SLAC

FACET-II is a National User Facility offering unique capabilities for the advancement of accelerator science. Utilizing high-energy electron beams, it enables state-of-the-art research in advanced acceleration methods, ultra-high-brightness beam generation, and novel radiation sources. Here, we provide an overview of the FACET-II facility and highlight its experimental infrastructure, which is accessible to the scientific community through a competitive user program.

Speaker: Ivan Rajkovic (SLAC National Accelerator Laboratory)

16:00 Passive plasma lens experiments at FACET-II

The beam-driven, passive plasma lens can provide axisymmetric focusing with strengths orders of magnitude greater than conventional quadrupole magnets, while remaining ultra-compact. These characteristics make it attractive for beam matching into a plasma wakefield accelerator and for controlling beam divergence downstream of plasma stages. Optimal performance can be achieved in the underdense regime, resulting in a linear focusing force and emittance preservation of the focused beam. We report progress on experimental results from SLAC’s FACET-II facility, where we utilized a fs Ti:Sapphire laser pulse to ionize hydrogen gas from a supersonic gas jet to focus several hundred pCs of charge of a 10 GeV electron beam.

Speaker: Mr Shutang Meng (University of Colorado Boulder)

16:00 Performance enhancement of medium temperature baked niobium SRF cavity by surface contamination removal

Medium temperature baking (300- 350 °C) enhances the quality factor of niobium superconducting radio frequency cavities. However, surface contamination introduced during vacuum furnace baking limits the quench field and may also degrade the quality factor of the cavity. To investigate this effect, a 1.3 GHz single-cell Nb cavity underwent mid-T baking, followed by a chemical treatment to remove the surface contaminants. Post-treatment measurements revealed a significant improvement in both the quality factor and the quench field.

Speaker: Vijay Chouhan (Fermi National Accelerator Laboratory)

16:00 Plasma processing of SRF cavities at Jefferson Lab: Experiment results and simulation insight

Plasma processing of superconducting radio frequency (SRF) cavities has been an active research effort at Jefferson Lab (JLab) since 2019, aimed at enhancing cavity performance by removing hydrocarbon contaminants and reducing field emission. In this experiment, processing using argon-oxygen and helium-oxygen gas mixtures to find minimum ignition power at different cavity pressure was investigated. Ongoing simulations are contributing to a better understanding of the plasma surface interactions and the fundamental physics behind the process. These simulations, combined with experimental studies, guide the optimization of key parameters such as gas type, RF power, and pressure to ignite plasma using selected higher-order mode (HOM) frequencies. This paper presents experimental data from argon-oxygen and helium-oxygen gas mixture C75 and C100 cavity plasma ignition studies, as well as simulation results for the C100-type cavity based on the COMSOL model previously applied to the C75 cavity.

Speaker: Nabin Raut (Thomas Jefferson National Accelerator Facility)

16:00 Power coupler and tuner design for a 2 MeV Distributed-Drive Linac

A distributed-drive linac consists of individually powered and phased single- cell cavities. In this paper, we evaluate options for coupling RF power into the linac cavities, and present an initial design for a cavity frequency tuning mechanism.

Speaker: Mr Benjamin Sims (Michigan State University)

16:00 Prelimimnary introduction of the IOTA Bake System

The IOTA ring is vital to the advancement of accelerator sciences, and a large part of its attractiveness to accelerator physicists is its modularity and the versatility that this function provides. Up until this point, the FAST accelerator has provided electron beam for the studies in IOTA. With the soon to be commissioned IOTA Proton Injector in lieu, the requirement for better vacuum to support future proton studies in the ring have arrived. Our solution is the IOTA Bake System which has the goal of facilitating this requirement.

Speaker: Travante Thompson (Fermi National Accelerator Laboratory)

16:00 Preliminary computational study on minimizing longitudinal emittance in photoinjector

Recently, we proposed a novel photoinjector that incorporates an emittance exchange (EEX) beamline. Previous studies demonstrated promising 4D emittance performance of an EEX-based injector, but the beam’s longitudinal emittance at the linac exit still limits the final transverse emittance downstream of the EEX stage. We performed a comprehensive scan of injector parameters—including gun phase, laser spot size and pulse length, and solenoid strengths—to (1) estimate the minimum achievable longitudinal emittance, (2) identify sources of emittance growth, and (3) explore mitigation strategies. Here, we present the status of this study. Simulations were carried out using General Particle Tracer (GPT) including space-charge effects.

Speaker: MinKyu Seo (Korea University Sejong Campus)

16:00 Progress update on compressed ultrashort pulse injector demonstrator

Stable high gradient operation of a photoinjector is important for generating high brightness electron beams. The Argonne Wakefield Accelerator (AWA) facility recently commissioned an X-band photoinjector at \SI{400}{\mega\volt/\metre} cathode field without significant breakdown rates using nanosecond RF pulses generated from a wakefield accelerator. We propose to develop an X-band photoinjector at \SI{500}{\mega\volt/\metre} cathode field fed by ultrashort RF pulses generated by RF pulse compression technology developed at SLAC National Accelerator Laboratory, named as Compressed Ultrashort Pulse Injector Demonstrator (CUPID). The klystron based pulse compression is more stable and allows higher repetition rate. Here we provides the progress update of CUPID project, in particular on the mechanical design of the electron gun, solenoid's requirement and design constraints.

Speaker: Wei Hou Tan (SLAC National Accelerator Laboratory)

16:00 Progress of polarized ion sources at BNL

The OPPIS has undergone multiple upgrades since 2000, with the most recent completed in 2022. Improvements to the Rb and Na cells have reduced vapor dispersion in the beamline, significantly lowering consumption and improving source stability. Plasmatron modifications extended component lifetimes. These upgrades enabled reliable Run-24 operation, with a mean current of 350 μA, 300 μs pulse width, and ~80% polarization delivered at the 200 MeV linac exit.

Development is also underway for a high-intensity (2×10¹¹ ions/pulse) polarized ³He⁺⁺ source for the future EIC. The approach uses metastability-exchange optical pumping of high-purity ³He gas in a strong magnetic field, followed by ionization in EBIS. In tests with an “open” cell, 80–85% polarization has been achieved. The final gas cell configuration is now being tested with a 5 T EBIS solenoid magnet.

Speaker: Deepak Raparia (Brookhaven National Laboratory)

16:00 Progress of the Plasma Acceleration Research Platform at IHEP

Plasma acceleration is an innovative principle characterized by high acceleration gradients, which has attracted significant interest from major accelerator laboratories worldwide, because of its potential to increase accelerator energy and reduce size. One promising approach involves using existing conventional accelerators as external injectors for plasma-based accelerators, a topic of considerable interest within the research community. At IHEP, we propose utilizing the BEPCII Linac in conjunction with a new linac based on a photocathode RF gun to develop a new plasma acceleration research platform. This manuscript presents recent progress in the development of this platform.

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

16:00 Progress on commissioning of the CARIE facility at LANL

The cathodes and RF interaction at extremes (CARIE) is a project in Los Alamos National Laboratory (LANL) that aims for generating a high-brightness electron beam from a high-gradient photocathode. The commissioning of the CARIE facility started in 2022. A 50 MW C-band klystron was conditioned in 2023. A waveguide line including a high-power circulator was constructed and conditioned up to 12 MW in 2024. The facility has new control and logging systems currently being in implementation. An RF injector without a cathode plug was successfully tuned and is ready for installation. This talk will present the progress on commissioning and outlook of the project.

Speaker: Wonjin Choi (Los Alamos National Laboratory)

16:00 Progress report on two-bunch excitation of wakefield in dielectric structures

Wakefield accelerators have the potential to achieve accelerating fields in the GV/m range, offering a promising path to more compact and cost-effective acceleration compared to conventional methods. Structure-based wakefield accelerator (SWFA) technology provides a viable approach to implementing beam-driven wakefield acceleration. An experiment at the Argonne Wakefield Accelerator (AWA) will utilize dielectric-lined structures to explore multi-beam excitation of wakefields for wakefield-pulse shortening and mapping of the transverse wakefield topology. These structures were commercially sourced and require a thin metallic film deposited on their outer surface. The first part of this paper summarizes the preparation of these structures. In parallel, a two-bunch beam configuration is required to support the experimental investigation, where one bunch excites the wakefield and the second serves as a loading or probe bunch. The experimental generation and testing of this two-bunch scheme at AWA are presented in this work.

Speaker: Calcifer Phillips (Northern Illinois University)

16:00 R&D Progress of electron cyclotron resonance accelerator

Several attractive features of a novel electron Cyclotron Resonance Accelerator (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. Hence an eCRA can be highly compact and efficient to produce high power electron beams and x-ray beams. The applications of the eCRA includes the replacement of Cs-137 based dosimeter calibration system, and the replacement of Co-60 based sterilization system. The R&D progress of eCRA is reported here. A 2 MeV eCRA Demonstrator is under construction at BNL to validate the eCRA acceleration mechanism experimentally. A 5 MeV eCRA Upgrade with high beam power is in the design phase.

Speaker: Yong Jiang (Particle Accelerator Research Foundation, Omega-P R&D, Inc.)

16:00 Radiation Dose Simulations on Permanent Magnets for the CEBAF Energy Upgrade

The ongoing work related to the LDRD funded by JLab is investigating the effects of radiation on permanent magnet materials intended for use in the CEBAF energy upgrade. This effort combines experimental exposure of magnet samples to radiation rates within the accelerator with detailed simulation studies. Samples are positioned at various locations to capture a range of radiation environments, helping researchers assess how different doses influence magnetic performance over time. Simulations using BDSIM support the interpretation of measured results and extend predictions to the higher energy stages planned for CEBAF. This paper presents recent findings and outlines the progress made toward understanding the long-term behavior of these materials in high-radiation settings.

Speaker: Bamunuvita Gamage (Thomas Jefferson National Accelerator Facility)

16:00 Radio-frequency hardware considerations for a high-power solid-state amplifier

A feasibility study is developing a prototype solid state power amplifier to supplant or replace 805 MHz klystrons powering the coupled-cavity linac at the Los Alamos Neutron Science Center (LANSCE). We are considering the RF passive hardware used for such an amplifier. The power from individual transistor pallets that provide 5 kW each must be power-combined to the requisite 1.25 MW needed to replace a klystron. Various approaches are being considered for combining Additionally, the protection of the various components from reflected power is essential to avoiding damage to the pallets and all of the passive RF components such as combiners and connectors. The use of magic tees as both combiners and isolators is discussed, and circulators are another critical component for this design. Finally, as power is combined, another concern is the power handling of connectors, and the balance between performance and the practicality of the large number of connectors becomes crucial.

Speaker: Wesley Hall (Los Alamos National Laboratory)

16:00 Recent Efforts on Rebuilding LANSCE CCL Klystrons

The Los Alamos Neutron Science Center (LANSCE) uses forty-four (44) 1.25-MW 805-MHz klystrons to power its side-Coupled Cavity (CCL) linear accelerator (LINAC). In recent years, the facility has experienced a significant klystron failure rate and dwindling hot spare inventory, producing ample beam downtime and reliability risk. This paper presents a LANSCE case study on rebuilding a klystron, a first attempt to revitalize a manufacturing technology that was vibrant for decades as LANSCE. We present data collected during the klystron’s initial testing alongside pre-failure (i.e. live) performance. Our failure analysis investigates possible causes given observed irregularities in the data collected. Rebuilding efforts to address all failure modes are presented, highlighting our troubleshooting and refurbishment process, methods, and techniques. We end our discussion by presenting post-rebuild results, lessons learned, and potential future improvements.

Speakers: Aditya Waghmare (Los Alamos National Laboratory), Mr Cole Cochran (Los Alamos National Laboratory)

16:00 Recent LANSCE efforts on improving H+ duoplasmatron capabilities

LANSCE uses a duoplasmatron ion source to produce H+ ion beams for the Isotope Production Facility, which uses 100 MeV proton beams to produce a variety of therapeutic and diagnostic isotopes for research purposes and also supports a variety of other experiments for materials and nuclear physics. We have recently begun work to improve the reliability, peak current, and lifetime of the ion source, while restoring existing capabilities to build new ion sources and filaments. This poster will cover these efforts, with a particular focus on the work to re-establish and improve the filament production capability and production of higher peak current beams.

Speaker: Evan Loftin (Los Alamos National Laboratory)

16:00 RF amplifier system reconfiguration plans for new DTL and RFQ

The first 100 MeV of acceleration for protons and H- ions at the Los Alamos Neutron Science Center (LANSCE) is presently accomplished with a Cockroft-Walton generator (750 keV), followed by four Alvarez drift tube linac (DTL) cavities commissioned in 1970. The RF duty factor is 12 %, leading to significant thermal loading in the room temperature copper structures. Increasing obsolescence and structural reliability problems have created the need for replacements to these systems. The LANSCE Modernization Project (LAMP) developed a conceptual design for the Medium Energy Beam Transport (MEBT) and the Drift Tube Linac (DTL) using new accelerator components. This approach utilizes a Radio Frequency Quadrupole (RFQ) and six replacement DTL cavities. The current 201.25 MHz radio-frequency power amplifier system was replaced 10 years ago and has demonstrated high reliability with Diacrode tube lifetimes over 60,000 hours. We propose an RF amplifier topology that leverages this RF system to provide the required power for the LAMP conceptual design through innovative reconfiguration of the amplifiers.

Speakers: John Lyles (Los Alamos National Laboratory), Wesley Hall (Los Alamos National Laboratory)

16:00 RF breakdown and dark current studies in short-pulse acceleration

Recent experimental studies at the Argonne Wakefield Accelerator (AWA) have shown that operating RF cavities with short pulses, only a few nanoseconds in duration, can raise the accelerating gradient to nearly 400 MV/m in a series of X-band structure tests. These results motivate further investigation into the breakdown physics underlying the short-pulse acceleration regime.
In this work, we present analytical models and numerical simulations of dark current dynamics in X-band cavities driven by short RF pulses. These studies explore key phenomena associated with RF breakdown across various time scales, including field emission, secondary electron emission, and plasma formation, with particular focus on their dependence on RF pulse length.
Building on these insights, we describe the design and experimental plan for a single-cell X-band RF cavity operating at 11.7 GHz, optimized for high-gradient operation with 6~ns long RF pulses and integrated with RF breakdown diagnostics.
This work aims to deepen the understanding of RF breakdown physics in the short-pulse regime and support the development of compact linear accelerators for future applications.

Speaker: Gaurab Rijal (Northern Illinois University)

16:00 Science enabled by the the FACET-II low-energy laser arm

The FACET-II 10 TW laser system enables a variety of studies ranging from plasma wakefield acceleration over laboratory astrophysics to strong-field QED. While we successfully improved the performance of the high-energy laser-arm has, the much more versatile low-energy arm has yet to keep up. We report on the currently ongoing efforts to improve the performance of the low-energy laser-arm performance. The improvements are expected to enable studies, such as ultra-low emittance electron beams from plasma accelerators, plasma lenses, and novel ultrafast beam diagnostics.

Speaker: Dr Alexander Knetsch (SLAC National Accelerator Laboratory)

16:00 Simulating dielectric wakefield acceleration of positrons from a solid target converter

Positrons and electrons can be generated by impinging a relativistic electron beam onto a solid converter, sometimes referred to as a non-neutral fireball beam. Depending on the scenario, a substantial fraction of the incoming driver bunch may still have sufficient quality to drive high gradient (~GV/m) accelerating wakefields in a dielectric structure. Here we consider the design of a dielectric loaded waveguide, positron converter, and electron driver bunch structure to realize capture and GV/m dielectric wakefield acceleration of positrons at SLAC FACET-II.

Speaker: Nathan Majernik (SLAC National Accelerator Laboratory)

16:00 Sputter coating of Nb₃Sn into SRF cavity using stoichiometric target

Nb₃Sn has emerged as a leading alternative material due to its higher superconducting critical temperature (Tc) and superheating field (Hsh), promising a viable solution to the intrinsic performance limit currently faced by Nb superconducting radiofrequency (SRF) cavities. We sputter-coated Nb₃Sn inside Nb SRF cavity using a stoichiometric Nb₃Sn tube target in a DC cylindrical magnetron sputter coater. The target was fabricated by growing an estimated >20 μm thick Nb₃Sn layer on a Nb tube via Sn vapor diffusion using Jefferson Lab’s coating system. Approximately 150 nm thick Nb-Sn films were sputter-deposited onto flat Nb samples at positions representing the beam tubes and equator of a 2.6 GHz Nb cavity. Post-deposition annealing at 950 °C for 3 h resulted in the formation of Nb₃Sn. Microstructural analysis of the annealed films was carried out to investigate the morphology and structure of the Nb₃Sn films. Later, a 2.6  GHz Nb SRF cavity was coated with a ~1.2 μm thick sputtered Nb-Sn film using a stoichiometric Nb₃Sn target, followed by annealing. Cryogenic RF testing of the annealed cavity demonstrated a Tc of 17.8 K, indicating the formation of Nb₃Sn. After a light Sn recoating treatment, the cavity achieved a quality factor (Q0) of 6.7E+08 at lower field at 2.0 K.

Speaker: Md Sharifuzzaman Shakel (Old Dominion University)

16:00 Start-to-end simulations of a compact, linac-based positron source

Slow positrons are increasingly important to the study of material surfaces. For these kinds of studies, the positrons must have low emittance and relatively high brightness. Unfortunately, fast positron sources like radioactive capsules or linac driven sources have broad energy and angular spread, which make them difficult to capture and use. Moderators are materials that produce slow, mono-energetic positrons from a fast positron beam. Since their efficiencies are typically less than $10^{-3}$ slow $e^+$ per fast $e^+$, research into how to maximize efficiency is of great interest. Previous work has shown that using a linac, one can decelerate the fast positron beam in order to greatly increase moderation efficiency. We present here start-to-end simulations using G4beamline to model a 100~MeV electron beam incident upon a Tungsten target, focused by an adiabatic matching device, and decelerated by a 1.3~GHz, 5-cell pillbox cavity. We show that by decelerating the positrons after their creation we can increase the number of positrons under 500~keV by 15 times, translating to a 16.3 times improvement in moderation efficiency, and therefore leading to a brighter positron source.

Speaker: Sophie Crisp (SLAC National Accelerator Laboratory)

16:00 Status of the experimental demonstration of GW power generation from THz-TBA

We present the current status of preparations for the experimental demonstration of GW power generation from THz-TBA. The presentation will cover the status of structure fabrication, RF power extraction and absolute power measurement, and THz drive beam preparation. Currently, 0.4 THz structures are being fabricated using two improved methods over previous fabrication techniques. RF power extraction will be achieved using an on-axis elliptical horn antenna and off-axis parabolic mirrors. The RF power will be detected with a bolometer and calibrated based on the total beam energy loss measured by a spectrometer. In recent machine studies, we successfully generated a high-charge bunch train (1 nC/bunch) compatible with 0.4 THz structure.

Speaker: Gwanghui Ha (Northern Illinois University)

16:00 Study of uncorrelated resonance crossing in a controlled environment

This paper deals with estimating spin depolarization in planned very high energy electron-positron storage rings like the FCC-ee. The paper covers three aspects of the work: 1) the putative so-called uncorrelated resonance crossing due to noise in the spin-rotation phase advance caused by photon emission in synchrotron radiation. This is expected to suppress the depolarization caused by synchrotron sideband resonances, 2) a study of the performance of our code on multiple high performance systems, and 3) the novel exploitation of a high order Magnus expansion applied to spin transport. The study uses Monte-Carlo spin-orbit tracking for a simple model of spin motion, the so-called single resonance model, augmented by the effects of radiation. The results presented here represent the first steps of a planned detailed large-scale exploration.

Speaker: Jack Kelley (Virginia Tech, Los Alamos National Laboratory)

16:00 The Pulsed Ion Reflex Klystron: A new accelerator for high efficiency voltage conversion

Beam Alpha developed a kilowatt-scale fusion microreactor that directly converts nuclear energy to electrical energy without intermediate heat steps. This device has an output of 1.6 million volts DC. A converter is needed to transform this potential energy into useful electrical power. To achieve this the "Pulsed Ion Reflex Klystron" has been developed. The PIRK aims to achieve high conversion efficiencies by directing negatively charged ions through a re-entrant resonant cavity hundreds of times to gradually transfer energy from the moving particles to said cavity. Ions will be released into a 6-meter linear accelerator with roughly 1000 precisely spaced electrodes forming a quasi-parabolic potential. This potential is symmetric about the midpoint of the tube causing ions to oscillate with a frequency of approximately 1 MHz independent of energy. Perturbations to this parabolic potential are designed to provide radial electrostatic beam focusing. An algorithm is devised to produce optimal voltage curves to maximize both longitudinal bunching and radial confinement, and these curves are examined against practically realizable potentials. Energy is coupled out of the resonant cavity using a loop antenna connected to a silicon carbide rectifying diode. This converts the RF in the cavity to a 400V intermediate DC bus that can easily be inverted to wall power.

Speaker: David Mengel (Beam Alpha Incorporated)

16:00 Thermal analysis and preliminary cooldown performance of the SCU cryostat

The SCU cryostat, featuring two 1.5-meter-long Nb-Ti superconducting undulators (SCUs), is currently being built for the Advanced Photon Source Upgrade. The final design, along with the thermal and mechanical models of this cryocooler-cooled, liquid helium-based cryostat, has been completed. The cryostat has been fabricated, and preliminary cool-down tests were conducted both with and without the two 1.5-meter-long Nb-Ti SCUs. This paper presents a comparison between the measured and calculated thermal performance of the cryostat.

Speaker: Yuko Shiroyanagi (Argonne National Laboratory)

16:00 Thermal Performance of a 50 kW Minichannel Beam Dump at FRIB

The Facility for Rare Isotope Beams (FRIB) produces high-intensity, high-purity rare isotope beams through interactions between a primary beam and a graphite production target, currently operating at approximately 20 kW of primary beam power. To absorb unreacted primary beams downstream of the production target, an intermediate beam dump, called the minichannel beam dump (MCBD), was developed and implemented. The MCBD features a static structure tilted at 6°, which reduces the surface power density by a factor of 10. It is fabricated as a bimetallic assembly with a high-thermal-conductivity copper alloy absorber and aluminum alloy cooling channels (2 mm wide × 7 mm high) to mitigate oxidation and enhance heat removal. The system’s thermal performance was experimentally validated using a 17 keV electron beam, with measured surface temperatures agreeing with CFD simulations within 10%, confirming its reliability for higher-power operation. The current system is thermally limited by the temperatures at the absorber and wing surfaces. To enable operation at 50 kW, geometric optimization was performed by adjusting the surface angle across the entire structure to more effectively distribute heat on the copper absorber and reduce the thermal load on the aluminum wings. This work presents both thermal validation and simulation results demonstrating enhanced cooling performance with the optimized MCBD design for 50 kW beam operations at FRIB.

Speaker: Jeongseog Song (Facility for Rare Isotope Beams)

16:00 THz Detection and Investigation of Vacuum-Compatible Optical Components

Detecting terahertz (THz) radiation in ultra-high vacuum (UHV) environments presents notable challenges due to the limited availability of commercially compatible components. In preparation for upcoming THz measurements at the Argonne Wakefield Accelerator (AWA) facility, we investigated two critical aspects: (1) the THz transmission characteristics of fused silica windows, and (2) the suitability of commercial off-axis parabolic mirrors (OAPs) for use in UHV conditions. While fused silica is widely used in optical systems, its performance in the THz regime is rarely documented. We present transmission measurements and assess its viability for THz diagnostics. Additionally, we address the incompatibility of anodized, off-the-shelf OAPs with UHV by developing and testing both mechanical and chemical de-anodization techniques. These methods aim to maintain surface integrity and optical quality. This work provides practical guidelines and compatibility benchmarks for implementing THz diagnostics in UHV environments and serves as a reference for future experiments at AWA and other accelerator facilities.

Speaker: Calcifer Phillips (Northern Illinois University)

16:00 Transverse deflecting cavity optimization for active control of electron beam energy chirp

The Transverse Deflecting Cavity Based Chirper (TCBC) is a novel concept of imposing and removing a significant energy chirp of an ultra-relativistic electron beam. The TCBC method requires much less footprint, compared to the conventional chirping and dechirping method involving operating a linear accelerator off-crest. When the compressed bunch is very short, the dechirping has to rely on the wakefields. We present our updated design of the L-band traverse deflecting cavity (TDC) for demonstrating the TCBC concept at the Argonne Wakefield Accelerator (AWA) facility. Our TDC design update is based on the original design provided by Tsinghua University. The TDC design update focused on ensuring improved performance under more intense electromagnetic fields, reducing the peak pulsed temperature rise. The tuners of the TDC were meanwhile reworked to allow greater adjustability of the resonant frequency and of the electromagnetic field balance among the cells. We also report the tolerance study of the TDC. Two copies of the TDC with the updated design are currently under fabrication with Dymenso, LLC.

Speaker: Haoran Xu (Los Alamos National Laboratory)

16:00 UED/UEM Conduction cooled Nb3Sn SRF photogun commissioning results

SRF photoguns become a promising candidate to produce highly stable electrons for UEM/UED applications because of the ultrahigh shot-to-shot stability compared to room temperature RF photoguns. SRF technology was prohibitively expensive for industrial use until two recent advancements: Nb3Sn and conduction cooling. SRF gun can provide a CW operation capability while consuming only 2W of RF power which eliminates the need of an expensive high power RF system and saves a facility footprint.
Euclid is developing a continuous wave (CW), 1.5-cell, MeV-scale SRF conduction cooled photogun operating at 1.3 GHz. In this paper, we present commissioning results of the gun in the newly developed conduction cooled cryomodule with beamline integration.
The project is funded by DOE SBIR #DE-SC0018621

Speaker: Chunguang Jing (Euclid Techlabs (United States))

16:00 Ultra-violet laser transverse shaping with phase plates

Shaping ultraviolet (UV) laser beams is critical for optimizing photoinjector performance for applications in free-electron lasers (FELs). It has been shown that a 50% truncated Gaussian beam can achieve the lowest emittance via space charge compensation at LCLS-I. However, conventional shaping techniques to prepare this beam are limited by significant power losses or are not adapted for UV light. Here we report a high-precision transverse-shaping technique based on custom fused-silica phase plates with >99 % transmission at 253 nm. This approach enables spatial beam profile tailoring and significantly enhances beam stability at the photocathode. Using IMPACT-T simulations, we predict a 33% (from 0.67um to 0.45um) reduction in normalized emittance for a 250 pC bunch at LCLS-I. Experimental implementation at FACET-II demonstrated a 37% emittance reduction (from 5.4um to 3.4um) at 1.6 nC. These results establish phase-plate beam shaping as a high-fidelity, low-loss approach for high-brightness photoinjectors. Implementation at LCLS-II which will enable stable operation at megahertz repetition rates is underway.

Speaker: Nathan Majernik (SLAC National Accelerator Laboratory)

16:00 Understanding the RHIC triplet magnet vibrations in preparation for EIC

Throughout its operation, the RHIC triplet magnets have been subject to a mechanical vibration around 10 Hz. These mechanical vibrations were found to produce a beam orbit jitter that was detrimental to the collider luminosity. During RHIC operation, this has been effectively mitigated by the implementation of a fast feedback orbit control system. For the Electron Ion Collider (EIC) Hadron Storage Ring (HSR), the RHIC triplet package will be modified, magnets will be removed, and the cryogenic lines will be rearranged inside the cryostat. A comprehensive analysis of the RHIC triplet vibration has been undertaken to ensure that the planned triplet piping modifications would not increase the current triplet magnet vibrations and overwhelm the existing fast feedback control system. This paper aims to describe the current understanding of the root cause and kinematic of the RHIC triplet vibrations and offer mitigation options for EIC.

Speaker: Frederic Micolon (Brookhaven National Laboratory)

16:00 Upgraded photoinjector laser pulse train generator at the Argonne Wakefield Accelerator

The Argonne Wakefield Accelerator (AWA) facility operates a high-charge (100s of nC) electron beam in a bunch train, with eight electron bunches at a 769 ps spacing matching the linac operating frequency of 1.3 GHz. AWA’s electron beam is optimized for producing large wakefields in resonant structures to study structure wakefield acceleration. This is achieved by maximizing total beam charge, and by correct bunch train timing to enhance the wakefield via inter-bunch coherence. The properties of the bunch train are determined by a “multisplitter” in the photoinjector laser system, in which a series of beamsplitters splits one laser source into eight - ideally equal - pulses. However, AWA’s previous system did not split pulses evenly, with up to a 2:1 ratio between pulse energies within a train. Damaging electrical breakdown events within the electron gun, driven by high single bunch charge, occurred at lower total charge in this non-uniform set-up, limiting maximum charge. Thus, a new multisplitter using polarizing beamsplitters and half-wave plates (HWPs) was implemented. Unlike the previous fixed-ratio beam-splitter design, the new system enables tuning the splitting ratio for each beamsplitter, resulting in a more uniform pulse train. Large 2” optics and uncoated HWPs are also used to increase the laser intensity damage threshold (LIDT). This paper presents the design, characterization and lessons learned in early commissioning of AWA's upgraded laser pulse train generator.

Speaker: Rachel Margraf-O'Neal (Argonne National Laboratory)

18:30 → 20:00 WISE

Thursday 14 August

08:00 → 09:00 Coffee

09:00 → 10:30 Thursday Tutorial

09:00 RF Sources for Accelerator Applications

This tutorial will begin with a brief historical account and review of technological developments and innovations in radio frequency (RF) systems for particle accelerators. After an introduction, we will provide more in-depth review of technological developments of RF sources for particle accelerators and will provide some perspectives on the state-of-the art RF sources tailored designed for a variety of particle accelerators applications.

Speaker: Prof. Alireza Nassiri (Argonne National Laboratory)

09:00 → 09:30 Beam Instrumentation, Controls, AI/ML, and Operational Aspects (Invited)

09:00 Advanced ML methods for beam tuning at FRIB

Experiments with rare isotope beams at FRIB are highly time-constrained, making rapid setup and delivery of high-quality ion beams critical to maximizing scientific output. The Bayesian framework is particularly well-suited for this challenge, offering sample-efficient optimization, principled incorporation of prior knowledge, and uncertainty-aware inference. In particular, Bayesian Optimization (BO) has proven to be an efficient and general approach for the non-sequential, static nature of beam-tuning tasks. To further accelerate convergence, Prior-Mean-Assisted Bayesian Optimization (pmBO) was developed, enabling rapid adaptation from prior belief to real-time machine conditions with minimal computational overhead. In parallel, a virtual diagnostic for the beam’s transverse quadrupolar moment (BPM-Q) has been developed to provide non-invasive, fast measurements of beam envelope information. To optimize the reconstruction of Courant-Snyder parameters from BPM-Q data, Bayesian Active Learning (BAL), employing a differentiable beam envelope simulator as a surrogate model, has been implemented. Together, these developments illustrate the power of Bayesian methods in achieving faster, more accurate beam-tuning.

Speaker: Kilean Hwang (Facility for Rare Isotope Beams)

09:30 → 10:30 Beam Instrumentation, Controls, AI/ML, and Operational Aspects (Contributed)

09:30 AI-driven neutrino diagnostics and radiation-hard beam instrumentation for next-generation neutrino experiments

The Long Baseline Neutrino Facility (LBNF) at Fermilab will deliver a high-intensity, multi-megawatt neutrino beam to the Deep Underground Neutrino Experiment (DUNE), enabling precision tests of the three-neutrino paradigm, CP violation searches, neutrino mass ordering determination, and supernova neutrino studies. To accelerate DUNE’s physics reach and ensure robust beam operations, we propose an integrated AI-driven framework with real-time diagnostics and radiation-hardened instrumentation. At its core is a Real-Time Beam Integrity Monitor using a physics-informed Digital Twin. By reconstructing pion phase space from muon profiles and exploiting magnetic horn optic linearity, it enables spill-by-spill beam correction and flux stabilization. By using this approach, flux-related systematics could be reduced from 5% to 1%, potentially accelerating the discovery of CP violations by four to six years. Complementing this, a US–Japan R&D effort will deploy a LAPPD-based muon monitor in the NuMI beamline. ToF measurements can be acquired with picosecond precision using this radiation-hard system, enhancing sensitivity to horn chromatic effects. Simulations confirm strong response to these effects. ML models predict beam quality and horn current to sub-percent accuracy from muon data, enhancing anomaly detection and stability. This scalable, AI-enabled strategy improves beam fidelity, reduces systematics, and sets a new standard for high-power accelerator operations.

Speaker: Sudeshna Ganguly (Fermi National Accelerator Laboratory)

09:50 Fermilab Booster beam loss modelling and rebalancing using Bayesian methods

To meet PIP-II upgrade requirements, Fermilab Booster losses need to be reduced by 50\% compared to present levels. So far, simulations are not good enough to predict loss patterns. Thus, an extensive Booster tune up will be necessary to achieve required performance. In this paper we present an effort to build a data-driven loss model using Bayesian techniques, and subsequently to rebalance losses for higher trip margins. We first created several sets of spatially and temporally isolated orbit and optics knobs, and trained Gaussian process models for each beam loss monitor as well as beam current. Novel techniques of uncertainty constraints and approximate GP fitting were introduced to handle safety and timing requirements. We then performed single and multi-objective tuning using scalarized objectives comprised of critical beam loss locations. We achieved significant rebalancing of losses, increasing margins by 25%, as well as an overall improvement in transmission efficiency of 0.4%. Automated data collection is being developed so that more accurate surrogate models can be trained over time.

Speaker: Nikita Kuklev (Fermi National Accelerator Laboratory)

10:10 Ultrafast THz detection and enhanced Electro-Optical timing for longitudinal beam diagnostics at Free Electron Lasers

This work presents advancements in precision longitudinal beam diagnostics for Free Electron Lasers (FELs), integrating zero-bias Schottky-diode-based THz detectors and upgraded electro-optical bunch arrival-time monitors (EO-BAMs) for low-charge operation. The developed THz detector achieves ps-scale response times and 70 GHz intermediate-frequency bandwidth, enabling single-shot THz detection across kHz–MHz repetition rates. Characterized from DC to 5.56 THz$^{*}$, it can serve as a critical tool for bunch compression monitoring$^{**}$ and lays the groundwork for future development ultra-broadband THz spectrometers. Concurrently, a novel printed circuit board (PCB) pickup structure enhances EO-BAM performance, preliminary results gave a slew rate of 275.7 mV/ps $\pm$ 34.6 mV/ps for a peak-to-peak voltage of 4.16 V $\pm$ 0.31 V at 3.45 pC after de-embedding$^{***}$.
Optimized PCB materials and planar designs improve signal integrity, achieving a simulated jitter-charge product of 9 fs·pC$^{****}$. This upgrade enables reliable operation at 1 pC for XFELs and ultrafast diffraction facilities while enhancing timing resolution in standard modes. The PCB architecture enables unprecedented flexibility for future multi-functional diagnostics. These innovations address critical challenges in low-charge, high-repetition-rate FEL diagnostics, advancing real-time beam characterization and accelerator optimization.

Speaker: Prof. Andreas Penirschke (Technische Hochschule Mittelhessen)

10:30 → 11:00 Coffee

11:00 → 12:30 Beam Dynamics and EM Fields (Invited)

11:00 Collective effects: Challenges and solutions for the EIC Project

The Electron-Ion Collider (EIC) project at Brookhaven National Laboratory aims to deliver groundbreaking insights into the fundamental structure of matter through high-energy collisions involving electrons, ions, protons, or helium-3 nuclei. Achieving the desired luminosity and maintaining stability in this complex accelerator environment pose significant challenges, particularly concerning impedance and collective effects. One such challenge is ensuring beam stability during electron cooling at the injection energy in the Hadron Storage Ring (HSR) to effectively mitigate proton emittance growth. Potential solutions include advanced simulation techniques using the ELEGANT code and applying the Haissinski solution for the proton beam to determine single-bunch instability thresholds, both with and without a second harmonic cavity.

Speaker: Alexei Blednykh (Brookhaven National Laboratory)

11:30 Comparison of predicted and measured collective effects in a fourth generation storage ring

Predicting, measuring, and mitigating collective instabilities in storage rings is important to maximize their performance. We will describe our efforts to theoretically compute and characterize collective effects during the design process, and how these continue during early operations. We then show how these predictions compare to measured collective effects at the APS-U, both with and without the harmonic cavity to lengthen the bunch.out using the harmonic cavity to lengthen the bunch.

Speaker: Ryan Lindberg (Argonne National Laboratory)

12:00 Halo formation in high-intensity Linacs: Modeling and advanced phase space diagnostics

Work at the SNS Beam Test Facility aims to characterize halo formation in the early stages of a high-power linac and to reproduce halo measurements with well-benchmarked particle-in-cell simulations. The BTF is equipped with advanced phase space diagnostics that enable detailed characterization of beam distributions at the beginning and end of a 2.5 MeV, 10 meter test beamline. Diagnostic capabilities include direct measurement of the 6D phase space distribution, as well as imaging of 2D phase space projections with 6 orders of magnitude in dynamic range. This talk will compare predictions from the PyORBIT code to measured distributions, as well as discuss the parameters and limitations of the simulation model.

Speaker: Trent Thompson (Oak Ridge National Laboratory)

11:00 → 12:30 Accelerator Technology and Sustainability (Invited)

11:00 How nitrogen and oxygen shape SRF cavity performance

Nitrogen and oxygen-based surface treatments have revolutionized the performance of superconducting radiofrequency (SRF) cavities, enabling them to reach higher gradients and lower losses. However, the exact mechanisms by which these treatments improve cavity performance remain largely unknown. This work provides new insights into the role of nitrogen and oxygen in SRF cavity performance by using time-of-flight secondary ion mass spectrometry (TOF-SIMS) to precisely quantify the concentrations and depth profiles of these impurities within niobium cutouts. We correlate these impurity profiles with detailed cavity performance measurements, including surface resistance and quality factor, and compare our findings with predictions from BCS theory. The results demonstrate that while both nitrogen and oxygen enhance performance, ten times more oxygen is required to achieve the same reduction in BCS resistance as interstitial nitrogen. We present a potential model in which the observed variation arises from nitrogen's greater effectiveness in trapping hydrogen, thus reducing the formation of niobium hydrides and enhancing superconducting gap.

Speaker: Hannah Hu (University of Chicago)

11:30 Achieving 10 MV cryomodule with Nb3Sn cavities

Nb$_3$Sn SRF cavities have the potential to reduce operating and capital costs for SRF accelerators. A first-of-its-kind Nb$_3$Sn 2-cavity CEBAF-type cryomodule has been assembled and tested. The cryomodule contains two 5-cell cavities: one coated and qualified by the team at Jefferson Lab and the other by the team at Fermilab. The cryomodule, assembled and tested at Jefferson Lab, achieved 10 MV accelerating voltage. This talk highlights steps during this development, including  cavity preparation and qualification, mitigations to avoid cavity performance degradation during string and cryomodule assembly, and cryomodule testing.

Speaker: Grigory Eremeev (Fermi National Accelerator Laboratory)

12:00 Accelerator Technology for the Electron Ion Collider

The Electron Ion Collider design includes sophisticated accelerator technology to produce high energy, high luminosity collisions with polarized beams. This talk overviews some of the key technologies, including a suite of different SRF cavities for accelerating and crabbing, cryogenics system, as well as high field interaction region magnets. The talk will also describe several examples where engineering decisions related to cost/performance and operational flexibility optimization needed to be made on the path for maturing the EIC design.

Speaker: Katherine Wilson (Thomas Jefferson National Accelerator Facility)

12:30 → 14:00 APS/IEEE Business Meeting: Meeting rooms #1/#2

12:30 → 14:00 Lunch

14:00 → 15:30 Award Session: Award Session: Plenary room

15:30 → 16:00 Coffee

16:00 → 18:00 Thursday Poster Session

16:00 3D Theory of the Ion Channel Laser

The ion channel laser (ICL) is similar to the free electron laser (FEL) but utilizes the electric field from a blowout regime plasma wake rather than the magnetic field from an undulator to oscillate particles. Compared to the FEL, the ICL can lase with much larger energy spread beams and in much shorter distances, making it an attractive candidate for a future compact plasma accelerator driven coherent light source. We present a novel full 3D theory of the ICL accounting for numerous effects including transverse guided mode shape, diffraction, frequency and Betatron phase detuning, and nonzero spread in energy and undulator parameter. This theory is used to predict the gain, radiation mode profile, gain bandwidth, and emittance and energy spread constraints of the ion channel laser.

Speaker: Claire Hansel (University of Colorado Boulder)

16:00 A compact 2D carbon beam scanner with interleaved saddle coils

Scanning magnets are used in proton and ion beam therapy to produce a radiation dose conforming to the cancerous tumor. In most existing beam delivery systems, two separate magnets are used to scan the beam in the transverse planes. To enable more compact systems and gantries, a combined function 2D scanner magnet with a short working distance is highly desirable. Earlier designs suffer from field non-uniformity in at least one plane. A compact 2D scanner magnet has been designed to produce high-field uniformity in both planes. The scanner was designed for carbon ions and could be easily scaled down for protons and other light ions. The design is based on saddle coils where the coils of the two magnets are interleaved to balance both field properties and power losses when scanning in both planes. The simulated field performance shows ~ 0.1% field uniformity in both planes within the useful aperture of the magnet . This represents a significant improvement over the prior art of the elephant-ear scanner design. Different design options and possible implementations will be presented.

Speaker: Brahim Mustapha (Argonne National Laboratory)

16:00 Advanced growth and characterization of alkali antimonide photocathodes for bright beam applications

The properties of the photoemitting electron sources are the most 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 letter, 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 also described in this paper.

Speaker: Tariqul Hasan (Northern Illinois University)

16:00 Advancing conduction-cooled 650 MHz SRF technology for industrial accelerators at Fermilab's IARC

The National Nuclear Security Administration (NNSA) funds the Illinois Accelerator Research Center (IARC) at Fermilab in developing a high-power, conduction-cooled Superconducting Radio Frequency (SRF) accelerator tailored for industrial applications requiring robust and efficient operation. A 650 MHz, 1.6 MeV, 20 kW SRF accelerator is currently under development, employing a conduction cooling approach to simplify cryogenic requirements and enhance accessibility for industrial use. The accelerator's control system is implemented on the Blinky-Lite platform, selected for its open-source architecture, secure remote access capabilities, and operational flexibility—attributes advantageous for industrial deployment and sustained operation. A dedicated beamline is designed to measure essential beam parameters and test the integrated performance of the accelerator and control systems, thereby validating their operational readiness for intended applications.

Speaker: Yichen Ji (Fermi National Accelerator Laboratory)

16:00 Advancing to 500 mA: High-Current Ramp-Up and Operational Experience at NSLS-II

Since the first light in 2014 at 50 mA, NSLS-II has steadily increased beam current, reaching 500 mA in October 2019. Along the way, various challenges were addressed, including RF power consumption, wakefield effects, and unexpected component heating. Key improvements included enhanced temperature monitoring with 600 new sensors, optimized RF spring installation, and the installation of a superconducting wiggler in 2022 to reduce vacuum heating further. As a result, vacuum temperatures now remain below 70°C at 500 mA. Extensive beam studies ensured stability for 29 beamlines, improving signal intensity, signal-to-noise ratio, and sample throughput. NSLS-II successfully operated at 500 mA in August 2023, with increasing high-current operational periods scheduled each year to enhance user experiments.

Speaker: Guimei Wang (Brookhaven National Laboratory)

16:00 An electrostatic fusion collider for interstellar propulsion

In order to reach the nearest star Proxima Centauri within a century, a distance of 4.224 light-years from our solar system, the average spacecraft velocity needs to be 4.2% of the speed of light. Therefore, according to the rocket equation, the weighted average exhaust velocity needs to be over 1% of the speed of light for reasonable ratios of dry mass to fuel mass. The fusion reactor architecture presented herein consists of an electrostatic charged particle trap that brings two ion beams into collision with equal and opposite momentum. The two fusion channels under consideration for interstellar missions are p/Li7 and He3/He3, utilizing an array of low mass electrodes that minimize interactions with fusion daughters escaping from the collision point and focused to generate thrust. A prototype colliding beam accelerator has been built to determine the viability of achieving collider luminosities commensurate with the requirements of this application. A novel architecture overcomes past Coulomb scattering limitations. Reactor and propulsion system design parameters are presented in this paper along with preliminary prototype operational results with deuterium collisions.

Speaker: Ms Grace Bittlingmaier (Beam Alpha Incorporated)

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 Automatic measurement of the stray magnetic field in the RCS locations of RHIC by using the SPOT robot

The Electron Ion Collider (EIC) will collide high energy and highly polarized hadron and electron beams with luminosities up to 10^34/cm^2/s. In the Conceptual Design Report baseline scope, the electron beams, accelerated in the Rapid Cycling Synchrotron (RCS), are vulnerable to the outside magnetic field due to its low injection energy at 400 MeV. In addition, when the Hadron Storage Ring (HSR) and Electron Storage Ring (ESR) are in operation, the leaking field from the HSR might also affect the operation of RCS, because they are close to each other. Mapping the stray magnetic field throughout the Relativistic Heavy Ion Collider (RHIC) tunnel is essential to assess its impact on potential low-energy electron beam injection. A robot dog (SPOT) is used to automate the measurement of this stray magnetic field during the RHIC (or future EIC) operation at any location continuously. This quadrupedal robotic technology can also be applied to other future applications, including radiation, temperature, pressure, and other properties measurement during EIC operation.

Speaker: Peng Xu (Brookhaven National Laboratory)

16:00 Beam bunchers for LANSCE modification project

The Los Alamos Neutron Science Center (LANSCE) accelerator complex delivers both protons and negative hydrogen ions with various beam time patterns simultaneously to multiple users. The LANSCE linac front end is still based on Cockcroft-Walton voltage generators. An upgrade of the front end to a modern, RFQ-based version – a part of the LANSCE Modernization Project (LAMP) – is now in the conceptual design stage. The LAMP will need beam bunchers both in the low-energy transport (LEBT, 100 keV) before RFQ, and in the medium-energy transport (MEBT, 3 MeV) after RFQ. We use CST modeling to develop buncher cavities for LAMP. A few RF cavity types for MEBT: re-entrant, quarter-wave, and half-wave – are considered and compared. The LEBT low-frequency buncher is different: it is based on a two-gap structure driven by an LC-circuit and used for beam velocity bunching.

Speaker: Sergey Kurennoy (Los Alamos National Laboratory)

16:00 Beam dynamics in LANSCE accelerator facility with lower energy

In operation of the LANSCE accelerator facility, occasionally it is required to provide beam at a lower beam energy than the nominal energy of 800 MeV. In this paper we examine the regime when the last sector of the LANSCE linear accelerator is off, so that the beam energy becomes 700 MeV. The purpose of our study is to evaluate beam quality and required changes in the accelerator setup. Simulations of lower energy beam dynamics were performed starting from the beginning of Coupled-Cavity Linac through Switchyard and beamlines to Proton Storage Ring (PSR), followed by the process of beam accumulation in PSR. The original design of injection beamline to the Proton Storage Ring at nominal energy of 800 MeV assumes elimination of cross-terms in beam 6D sigma-matrix at the point of injection to PSR; however, these terms are amplified when 700-MeV beam is injected. Comparison of beam dynamics with nominal and lower energy operation is presented.

Speaker: Yuri Batygin (Los Alamos National Laboratory)

16:00 Beam loss modeling and mitigation due to intra-beam stripping

Intra-Beam Stripping (IBS) is a critical beam loss mechanism in high-intensity H- linacs and presents a significant limitation to increasing beam power. This work presents a computational framework to evaluate and mitigate IBS-induced beam loss along the Spallation Neutron Source (SNS) LINAC. Our calculation is based on an analytic theory and involves evaluation of a 9D integral using the Monte-Carlo technique. We first benchmarked our calculations against simplified, analytically solvable cases. We then applied our algorithm to Gaussian bunches with a known probability density function (PDF). We next expanded our algorithm to arbitrary bunch distributions using the Neural Spline Flow (NSF) models trained on PyORBIT tracking data. In the future, we plan to validate our algorithm experimentally and apply it to design IBS mitigation strategies.

Speaker: Shivam Kakkar (University of Tennessee at Knoxville)

16:00 Beamline optics design of a new two-room treatment suite at the McLaren Proton Therapy Center

A fixed-beam, two room suite with upright chairs for patient positioning, is being installed at the McLaren Proton Therapy Center (MPTC). The MPTC is an operational, multi-room cancer treatment center. The new suite adds a third (A) and fourth (B) room by branching off upstream of the two clinically active half-gantry treatment rooms. This imposed a number of constraints on the beamlines of the new suite. The new beamline uses a Y-shaped selection dipole to switch between the suite’s room A and room B. The design was further constrained by the need to replicate the clinically active rooms’ beam characteristics at the new patient locations. This paper provides an overview of the methodology of the design studies for the new beamlines together with selected results. The work helped to establish the feasibility of installing a two-room treatment suite into a space originally designed for a gantry-based single treatment room.

Speaker: George Gillespie (G. H. Gillespie Associates (United States))

16:00 BeamNetUS at Brookhaven National Laboratory

BeamNetUS is a national network of accelerator facilities that aims to provide broader access to the unique capabilities of accelerated particle beams. Two facilities at Brookhaven National Laboratory are part of the inaugural year of BeamNetUS, the Accelerator Test Facility (ATF) and the Low Energy Accelerator Development (LEAD) facility, and are scheduled to each host one BeamNetUS user experiment.
The ATF features an RF photocathode electron LINAC, a femtosecond Ti:Sa laser, and a high-peak-power long-wave infrared (LWIR) laser. These tools can be synchronized for joint use or operated individually, facilitating the development of advanced beam manipulation and measurement techniques, accelerator and laser technologies, and the exploration of low-plasma-density regimes.
The LEAD facility provides an ultrafast electron diffraction (UED) apparatus, utilizing an RF electron gun and Ti:Sa laser to enable dynamic studies of material structures, as well as investigations involving low-energy electron beams.
In addition to these two accelerator facilities, Brookhaven National Laboratory provides administrative support for the network. Further expansion is planned for 2026, including both increased user hours at ATF and LEAD as well as the potential inclusion of several other facilities at the lab.

Speaker: Anusorn Lueangaramwong (Brookhaven National Laboratory)

16:00 Calculations of emittance measurements via inverse Compton scattering

Recent simulation work has indicated that next generation photoinjectors will be capable of delivering beams with emittances below 100 nm for bunch charges of a few hundred pico-Coulombs. Experimentally validating these results by measuring such emittances is challenging due to the high resolution required. Additionally, in some cases it is desirable for these characterization measurements to be non-destructive, and to have the capability of selecting subsets of the beam. One technique that has been considered is the use of inverse Compton scattering (ICS) spectra to measure the emittance. Here we present simulation results on the use of ICS to measure 50 nm – 500 nm emittances for a 250 pC bunch charge electron beam.

Speaker: Michael Kaemingk (Los Alamos National Laboratory)

16:00 Cesium Telluride Photocathodes: PLD assisted Epitaxial Growth

Photocathodes are fundamental to the advancement of electron accelerators and photon detectors. While ultrasmooth photocathodes produced by co-deposition processes have been developed, their beam brightness remains limited by surface and bulk disorders inherent to polycrystalline structures. Epitaxial growth offers a transformative pathway to address these challenges, enabling the production of high-brightness electron beams*. This work reports the pulsed laser deposition (PLD) assisted epitaxial growth of Cs2Te photocathodes on lattice-matched single-crystal substrates. Real-time growth monitoring via X-ray fluorescence (XRF) confirmed stoichiometric composition, while growth oscillations provided insights into the deposition process. The epitaxial nature of the films, characterized by a flat surface and high crystallinity, is validated through reflection high-energy electron diffraction (RHEED). Bulk crystallinity was further studied through X-ray diffraction (XRD) analysis. Spectral response of quantum efficiency (QE) with wavelength range 200 nm to 400 nm has been reported

Speaker: Dr Kali Prasanna Mondal (Brookhaven National Laboratory)

16:00 Commissioning of the Complex Bend Prototype Beamline

For the NSLS-II upgrade, a novel Complex Bend (CB) optics solution has been proposed to achieve near-diffraction-limited emittance. A key challenge in this design is the requirement for high-gradient quadrupoles (150 T/m) in a compact space. To demonstrate feasibility, a CB prototype was developed and tested using the NSLS-II linac beamline, scaling the beam energy to 100–200 MeV while maintaining strong focusing. The prototype utilized a 16-wedge symmetric Halbach permanent magnet design, achieving a gradient of 140 T/m within ultra-compact quadrupoles. The CB beamline was installed and commissioned in two phases, first as a strong periodic focusing element and later as a combined bending and focusing system. The beam commissioning results showed good agreement with theoretical models, confirming that the Complex Bend functions effectively as both a strong focusing and bending element by offsetting CB poles. This validates the strong focusing design of the Complex Bend for future synchrotron light source upgrades.

Speaker: Guimei Wang (Brookhaven National Laboratory)

16:00 Critical design issues of the novel multi-beam LANSCE front end

The proposed novel 100 MeV injector for the modernization of the LANSCE Accelerator Facility* is aimed to replace the existing injector based on 750-keV Cockcroft-Walton columns. The specific feature of the LANSCE accelerator is the simultaneous delivery of beams with multiple beam flavors to several targets. Acceleration of various beams in a single RFQ provides less flexibility for optimal adjustment of acceleration and focusing parameters concerning the existing LANSCE setup caused by differences in beam current, charge per bunch, and beam emittances. An important issue in the low-energy beam transport of the proposed injector is the different levels of space charge neutralization of the multi-component beam. Coupling between degrees of freedom in the presence of strong space charge forces of the beams results in unavoidable beam mismatch in the Front End and requires careful six-dimensional matching of beams with accelerator structures. The paper discusses key issues in the planned Front End and suggests ways to mitigate them.

Speaker: Yuri Batygin (Los Alamos National Laboratory)

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

Microbunched electron Cooling (MBEC), a type of Coherent electron Cooling (CeC), is a possible way to cool 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 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: Bamunuvita Gamage (Thomas Jefferson National Accelerator Facility)

16:00 Design Optimization of a Dual Energy Electron Storage Ring Cooler for Improved Cooling Performance

A dual energy electron storage ring cooler was proposed to maintain a good hadron beam quality against intra-beam scattering and all heating sources in a collider. This configuration has two energy loops. Electron beam in the low energy loop extracts heat away from the hadron beam through Coulomb interaction, while electron beam in the high energy loop loses heat through its intrinsic synchrotron radiation damping. Early studies of this concept show promising results and demonstrate its validity. This paper presented further optimization of optics design and parameters, and evaluation of improved cooling performance.

Speaker: Fanglei Lin (Oak Ridge National Laboratory)

16:00 Design Update of the ATLAS Multi-User Upgrade at Argonne

The ongoing multi-user upgrade of the superconducting ion linac, ATLAS at Argonne, will enable simultaneous acceleration and delivery of two different ion beams to different experimental areas. In the initial phase, one stable, nearly continuous wave, beam from the ECR ion source and one pulsed radioactive beam from the EBIS charge breeder of nuCARIBU will be interleaved in time via an electrostatic deflector at injection and accelerated through the first two sections of the linac. At that point, one of the beams is deflected via a pulsed switching magnet to a lower energy experimental area while the other is sent for further acceleration in the third section of the linac and delivered to a higher energy experimental area. In addition to enhancing the nuclear physics program at ATLAS, this upgrade will also increase the availability of beam time for some applications. While the construction and installation of the new pulsed injection beamline is now complete, there has been a change in the design of the extraction beamline. The original chicane designed to bypass the existing 40-deg bend has been removed, and the existing beamline was modified to incorporate the kicker and septum as the only required magnets. Details of the final design and progress made will be presented.

Speaker: Brahim Mustapha (Argonne National Laboratory)

16:00 Development of sodium potassium antimonide photocathodes for use of coherent electron cooling

The Coherent Electron Cooling (CeC) technique is a breakthrough in accelerator science, enhancing ion beam brightness in facilities like the Electron-Ion Collider (EIC). The success of CeC relies on high-performance photocathodes (PCs) for photoinjectors, where ideal PCs exhibit high QE, low emittance, long lifetimes, and minimal dark current. Alkali antimonide PCs meet these requirements. Among these, Na-K-Sb shows enhanced robustness, particularly under high-temperature conditions from high-power laser illumination, which generates high current electron beams. It also demonstrates improved vacuum stability and long-term QE consistency compared to other alkali antimonides like K2CsSb and Cs3Sb. These attributes make Na-K-Sb an effective choice for applications requiring both thermal and vacuum stability. This work presents the growth of Na-K-Sb PCs using the CeC cathode deposition system*, alongside detailed QE measurements and spatially resolved QE maps. These findings highlight the potential of Na-K-Sb PCs to advance CeC performance significantly and foster the development of high current, high-brightness electron sources for broader applications

Speaker: Dr Kali Prasanna Mondal (Brookhaven National Laboratory)

16:00 Development of superconducting adaptive gap undulator (SC-AGU)

The concept of the AGU has been proposed for some time*. However, utilizing a permanent magnet-based device complicates the design due to the necessity of independent gap control for each segment and, in the case of an in-vacuum undulator, the requirement for a flexible continuity sheet to mitigate image current heating. The adoption of SC magnets eliminates these concerns.
The SC-AGU prototype will comprise three sections of magnetic arrays with a total length of 120 cm, with the central section featuring a smaller gap than the end units. To achieve this, a UHV chamber will be designed for eventual fabrication, incorporating a non-uniform aperture that conforms to the beam envelope. Furthermore, to maintain a constant fundamental photon energy and maximize on-axis spontaneous emission, each SC section will be engineered with distinct period lengths, with the central section possessing a shorter period than the end units.
This paper presents the methodology for end-field analysis, encompassing detailed simulations to characterize the magnetic field distribution at the extremities of each magnetic array. Particular emphasis is placed on the impact of field quality at junctions and its influence on radiation properties, ensuring the optimization of on-axis spontaneous emission while preserving the electron beam’s ‘stay-clear’ area and mitigating impedance constraints imposed by the undulator magnet structure.

Speaker: Toshiya Tanabe (Brookhaven National Laboratory)

16:00 Development of the rocking curve imaging setup at BL17-2 at SSRL

We report on the implementation of the rocking curve imaging setup with a silicon (111) channel-cut crystal beam expander at Stanford Synchrotron Radiation Light source (SSRL) B17-2. B17-2 is a high-brightness, in-vacuum undulator (IVU) hard X-ray (~5 – 18 keV) beamline optimized for material scattering applications. Recently, we utilized it to perform rocking curve imaging (RCI) of diamond and silicon crystals. The expander is installed in addition to the previously existing RCI optics setup. We achieved horizontal beam magnifications of up to 1.38x at 6.951 keV and 2.25x at 9.831 keV. This work presents the updated RCI setup and experimental results to validate the performance of the Si (111) expander. Future improvements to the setup are also mentioned.

Speaker: Mario Balcazar (SLAC National Accelerator Laboratory)

16:00 Digital twin framework for PIP-II linac: AI-driven multi-scale modeling from ion source to 800 MeV

The PIP-II linac will enable >1.2 MW beam power for DUNE, requiring unprecedented operational reliability across its warm front-end (RFQ, MEBT) and five distinct SRF sections operating at 162.5/325/650 MHz. We present a comprehensive digital twin framework uniquely combining a fully differentiable fast beam transport code with neural network surrogates trained on high-fidelity PIC simulations, capturing space charge and nonlinear dynamics beyond traditional envelope codes while achieving 10⁴× speedup at <1% accuracy. End-to-end differentiability enables gradient-based optimization across 500+ parameters simultaneously—previously impossible with conventional tools—while the model incorporates static/dynamic errors and serves as a virtual commissioning platform for diverse hardware integration. The framework facilitates reinforcement learning for pulsed/CW mode transitions, predictive maintenance through anomaly detection, and autonomous tuning algorithm development with real-time execution capability. Validation against physics simulations shows excellent agreement for the front-end, with initial results demonstrating potential for 30% commissioning time reduction and proactive fault mitigation, providing a scalable blueprint for operating next-generation high-intensity accelerators.

Speaker: Abhishek Pathak (Fermi National Accelerator Laboratory)

16:00 Distributed Drive Linac Architecture for Compact Accelerators

The performance of solid-state amplifiers, across a range of metrics, has improved to the point where it is possible to construct a compact accelerator from individually phased and powered single-cell cavities. This distributed drive linear accelerator (DDL) architecture can provide significant advantages over conventional architectures in terms of power efficiency, redundancy, modularity, flexibility of operation, and fault tolerance. Compact DDL accelerators can fill increasing needs for medical and commercial applications, as well as more traditional roles in research, education and security. We have been studying how to advance this concept at Los Alamos National Laboratory, with a specific focus on a few-MeV, high-average-power concept, and overview our efforts and key results on power requirements, beam transport, and structure design.

Speaker: Leanne Duffy (Los Alamos National Laboratory)

16:00 Emulation of two-pass gain in a cavity-based XFEL via self-seeding at LCLS

This work presents an experimental study emulating a two-pass gain scenario in a cavity-based X-ray free-electron laser (CBXFEL) using a self-seeding configuration at LCLS. In this “7+7” arrangement, radiation generated by the first seven hard X-ray undulators (HXUs) is spectrally filtered by a high-resolution self-seeding crystal monochromator and used to seed a second set of seven undulators downstream. This setup mimics the regenerative amplification process expected in the CBXFEL cavity, where the seed pulse is recirculated and overlapped with a second trailing electron bunch. By systematically reducing the number of post-crystal undulators (from 13 to 5), we quantified the spectral amplification ratio by comparing the self-seeded peak signal to the SASE background. These results confirm the feasibility of seeding with the initial seven HXUs and provide a valuable benchmark for extrapolating gain in future two-bunch CBXFEL demonstration experiments.

Speaker: Mario Balcazar (SLAC National Accelerator Laboratory)

16:00 Evaluating a transition-jump system for the Fermilab Main Injector using Xsuite

We describe the development of a MADX-to-Xsuite simulation framework for the Fermilab Main Injector (MI) along with the subsequent evaluation of transition-crossing behaviors in the accelerator. In particular, we studied the introduction of quadrupole magnets into the lattice as part of a transition-jump system that will be implemented in the machine through the Second Proton Improvement Plan (PIP-II). Simulated beam losses spurred by transition-induced instabilities were assessed under several systematic effects, including MI quad errors, magnet-to-magnet variability in the jump magnets, emulated power supply errors, and timing jitter.

Speaker: Adam Schreckenberger (Fermi National Accelerator Laboratory)

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 Feasibility of proton bunch compression in an operational high-power accelerator

A muon collider would require short, intense proton bunches to generate the initial muon beam. Preliminary designs assume the proton bunches are formed by charge-exchange injection from a linear accelerator into an accumulator ring, followed by longitudinal compression in a separate ring. We aim to experimentally study this compression scheme at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL), which boasts a world-leading proton bunch intensity. The primary goal of these experiments is to benchmark simulations against turn-by-turn phase space measurements during the compression. Here, we describe the operating parameters of the SNS compared to the muon collider design, the capabilities of the current RF system, and the available beam diagnostics in the SNS accumulator ring. We also present initial simulations and experiments to judge the feasibility of the proposed research.

Speaker: Austin Hoover (Oak Ridge National Laboratory)

16:00 Feasibility studies of the stochastic cooling system in the proton storage ring EDM experiment

This study explores the feasibility of implementing stochastic cooling in the proposed proton electric dipole moment (pEDM) storage ring to be constructed at Brookhaven National Laboratory. Investigating fundamental physics phenomena, such as the electric dipole moment (EDM) of protons, demands highly precise experimental setups. In such precision experiments, intra-beam scattering (IBS) causes emittance growth, which degrades beam quality and limits the spin coherence time (SCT), a key parameter for sensitive EDM detection. The integration of a stochastic cooling system for stored polarized proton beams offers a potential solution by mitigating the effects of IBS, suppressing emittance growth, stabilizing beam dynamics, and enhancing the overall efficiency of the storage ring. This paper examines the feasibility of incorporating such a system into the proton EDM storage ring and evaluates its potential to preserve beam polarization and quality, both essential for advancing EDM experiment.

Speaker: Bhawin Dhital (Brookhaven National Laboratory)

16:00 Final design of CARIE photoinjector cavity with plug insert

At Los Alamos National Laboratory, we finalized the design of a 1.6-cell C-band RF photoinjector cavity for the Cathodes And Radiofrequency Interactions in Extremes (CARIE) project. The photoinjector cavity is intended to operate at 5.712 GHz, with an intense electric field on the photocathode up to 240 MV/m, producing 250-pC electron bunches at room temperature. The photoinjector cavity design focused on minimizing the peak electric and magnetic fields. The distributed RF coupling waveguide network design was optimized for achieving minimized vacuum pressure at the photocathode plug emitting surface. We report the RF simulation and vacuum simulation results of the photoinjector cavity. We also discuss the mechanical design considerations related to photocathode plug alignment, laser pipes, and baking out. The designed photoinjector cavity is currently under fabrication.

Speaker: Haoran Xu (Los Alamos National Laboratory)

16:00 Force-Neutral Adjustable Phase Undulators

Conventional variable-gap undulators rely on complex and bulky motion and support systems, limiting their tuning speed, precision, and overall efficiency. To address these challenges, RadiaBeam Technologies, in collaboration with Argonne National Laboratory (ANL), is advancing ANL’s Force-Neutral Adjustable Phase Undulator (FNAPU) technology by developing manufacturing capabilities and diagnostics testing capacity for efficient fabrication and reliable quality control of standalone undulator units.

FNAPUs utilize a secondary array of “off-the-shelf” permanent magnets that counterbalance the internal magnetic forces of the primary undulator array, enabling a compact, force-neutral structure. This design significantly simplifies assembly, improves alignment precision, and enhances operational safety and user accessibility. Furthermore, the compact and modular architecture of FNAPUs supports novel configurations such as X-undulators as well as enabling the integration of multiple units into undulator matrices, providing wide X-ray energy production via switchyard. These capabilities position FNAPU technology as a promising solution for next-generation light sources, including X-ray free-electron lasers (XFELs) and synchrotron radiation (SR) facilities.

Speaker: Tara Hodgetts (RadiaBeam Technologies (United States))

16:00 Four unique features of dynamical friction for magnetized and unmagnetized cooling of relativistic hadron beams

At energies relevant to electron cooling of future electron-hadron collider designs, the beam-frame interaction time in the cooler becomes short compared to the plasma period. In this regime, the interaction time cannot be taken as infinite for analytic calculations of dynamical friction, and the details of strong scattering with small impact parameter cannot be neglected. Three significant results from previous work (see Refs. $*$,$**$ and $***$) are presented. In the limit of strongly magnetized beams, dynamical friction depends on the sign of the charge. In this same limit, widely used parametric and semi-analytic formulas break down. For unmagnetized cooling, the impact parameters follow a modified Pareto distribution, such that the central limit theorem does not apply. At early times, the friction force is time-dependent in ways that can be surprising.

Speaker: David Bruhwiler (RadiaSoft (United States))

16:00 Free-Electron Laser Approaches to 6.x nm Generation for Blue-X Lithography

The shift of light source wavelength from 193 nm (Deep UV) to 13.5 nm (Extreme UV) in modern lithography tools has enabled mass production of semiconductor chips with feature sizes as small as 4 nm. To obtain smaller feature sizes, beyond EUV lithography (also known as Blue-X or EUVL Extension) at 6.x nm has been proposed.* Free-electron lasers (FEL), with output wavelength that is broadly tunable, can generate high-power 6.x-nm light. This paper compares different FEL approaches that have been experimentally demonstrated, albeit at other wavelengths, such as self-amplified spontaneous emission, regenerative amplifier FEL, harmonic lasing, etc. For this comparison, important factors under consideration are the electron beam energy and beam quality requirements, FEL efficiency, pulse energy fluctuations, spectral output, as well as suitability of the FEL output beam for use in Blue-X lithography.

Speaker: Dinh Nguyen (xLight Incorporated)

16:00 Growth and characterization of GaAs-based spin-polarized photocathodes

Spin-polarized electron sources find application in both high-energy and nuclear physics experiments. We describe in detail the design and characterization of different photocathodes based on GaAs/GaAsP superlattice structures. These structures are fabricated with a Distributed Bragg Reflector (DBR) aimed at achieving a high quantum efficiency (QE)~ 20\% in addition to a high electron spin polarization (ESP) ~85\% at the desired wavelength of 780 nm. We present the QE and ESP measurements of photoemitted electrons as a function of wavelength of incident light, along with morphological and photoluminescence measurements.

Speaker: Pallavi Saha (Brookhaven National Laboratory)

16:00 High Energy Heavy Ion Single Event Effects (HE HISEE): Planning for the future of microelectronics

One unique accelerator application is the testing of microelectronics for utilization in space. In particular, space provides two environment challenges that provide exposure to energetic heavy ions: galactic cosmic rays (GCRs) and solar particle events (SPEs). These particles cause risk by depositing charge in microelectronics potentially causing operational errors or even destructive failure.
Testing electronics with a variety of ground-based accelerators is not new. What is new is the increasing need for high-energy (> 100 Mev/n) heavy ions with ~40% of all testing predicted to require this high energy by 2030. This is primarily for two reasons:
- Mission-enabling advanced stacked microelectronics technologies such as 3D packaged devices that require higher energy to penetrate to the sensitive locations within these devices, and,
- Increase in demand to perform system-level testing using “large irradiation area” kinematics. This large area also allows for large sample sizes to be irradiated simultaneously for efficiency.
Presently, the is only one domestic accelerator that can achieve high energy heavy ions, that of Brookhaven National Laboratory’s NASA Space Radiation Laboratory. Here, we discuss the requirements needed by the test community and the domestic effort to close the gap in the number of test hours. A current government-funded study is underway to analyze options for the future.

Speaker: Dr Sandra Biedron (Element Aero)

16:00 Hollow-core anti-resonant fiber optics as a path towards practical laser-undulator based X-ray sources

This talk will outline the potential for commercially available, hollow-core, anti-resonant optical fibers to overcome many of the challenges in creating monochromatic and coherent x-ray sources with laser-electron beam interactions. The differences between inverse Compton scattering and laser undulators will be explored and the immense difficulty in creating a laser undulator outlined. A proposed innovation is to utilize modern day, commercial hollow-core fiber optics to confine the laser and potentially allow for a laser-undulator to be constructed with current state of the art lasers and electron beams. Models of this externally confined laser undulator concept will be presented and plans for upcoming experiments shown.

Speaker: Gerrit Bruhaug (Los Alamos National Laboratory)

16:00 Impact of Phase and Amplitude Instabilities on Beam Performance in the FACET-II LINAC

Maintaining RF stability in ageing accelerator infrastructure is essential for preserving beam quality and experimental integrity. At FACET-II, SLAC’s advanced test facility for high-gradient acceleration research, we investigate the cumulative effects of RF phase and amplitude jitter across legacy LINAC stations. This study quantifies how RF-induced instabilities contribute to inefficient charge delivery, beam loss, and longitudinal decoherence. Using diagnostics such as SYAG and DTOT2, we assess jitter-induced impacts on dispersion and orbit stability, and examine potential convolution into transverse beam losses. Amplitude and phase jitter are analyzed station-by-station, with correlations drawn to beam performance. We also evaluate the role of thermal fluctuations in klystrons and waveguides, and consider whether insulation degradation in SLED cavities may contribute to observed drift. We explore operational strategies to mitigate jitter effects. This work supports improved RF efficacy for better energy delivery, orbit control, and performance in energy-sensitive experiments such as PWFA.

Speaker: Marcellus Parker (SLAC National Accelerator Laboratory)

16:00 Implementation of an automated paradigm for alkali metal - metalloid photocathode growth

Alkali metal - metalloid photocathodes with positive electron affinity, such as Cs3Sb, K2CsSb, and Cs2Te, exhibit excellent quantum efficiency and reasonable emittance and lifetime. However, even when grown closed-loop, traditionally quantum efficiency alone is the feedback mechanism. Many advancements in the last decade have studied growth in situ, including with x-ray diffraction in beamlines and in molecular beam epitaxy with reflective high energy electron diffraction. However, an inexpensive, easily standardized feedback method is also desirable as a means to control stoichiometry during both single- and polycrystalline growth in commercial production. Recently stoichiometric control of cathode growth via a quantum efficiency ratio method has resulted in reliable, repeatable growths. * * We additionally report the implementation of an evolved high flux elemental cesium evaporator and our experience developing an industrial capacity for alkali metal - metalloid photocathode production. Cesium antimonide cathodes in co-deposition have consistent performance when utilizing carefully characterized fluxes in PID control loops and a slightly cesium-rich growth regime. We argue the automated paradigm for cesium antimonide paves the way for similarly simple yet robust industrial production of other alkali metal - metalloid photocathodes.

Speaker: Alexei Kanareykin (Euclid Beamlabs)

16:00 Implementation of electron–X-ray beam overlap diagnostic instrument at LCLS

We report on the commissioning results of the newly implemented Beam Overlap Diagnostic (BOD) instrument, known as Station F, at the hard X-ray line of the Linac Coherent Light Source (LCLS). As part of the CBXFEL project at SLAC, Station F is designed to facilitate alignment between the relativistic electron beam entering the undulator hall and the X-rays returning from the CBXFEL cavity via the return line. The station features two interchangeable targets: (1) a diamond screen for direct imaging of the LCLS electron beam, enabling measurement of its transverse size and position; and (2) a YAP:Ce scintillator for detecting faint returning X-rays when the diamond’s sensitivity is insufficient. Emission from either target, whether generated by electron-induced cathodoluminescence or X-ray-induced scintillation, is captured using a fast-gated optical/UV camera. We present results from recent commissioning runs, including direct electron beam imaging, beam size and position characterization in both single- and two-bunch modes, and observations of coherent radiation linked to early microbunching, with implications for the laser heater configuration.

Speaker: Mario Balcazar (SLAC National Accelerator Laboratory)

16:00 Improving sustainability of electron beam linac system

Fisica Applied Technologies, inc. (ATI) has designed and built e-beam sterilization systems, Flash-X-Ray systems, and many of the high pulsed power systems in the U.S. over the last 50 years. Our systems often use Sulfur hexafluoride (SF6 ) as an insulating gas. The global warming potential (GWP) of SF6 is approximately 23,500 times greater than carbon dioxide (CO2); because of this, there has been an increase in regulatory scrutiny and efforts to reduce SF6 emissions. Fisica has been successful in replacing SF6 with Dry Air (GWP <1) for many pulsed power applications and is investigating the use of other low-GWP gases. In this presentation, we will explore potential alternatives for transitioning our e-beam linac system from SF6 to environmentally sustainable, low-GWP gas alternatives.

Speaker: Yoko Parker (L3 Power Distribution - Applied Technologies)

16:00 IOTA experiment for proton pulse compression at extreme space-charge

A gammaT scheme may be required for the PIP-II era performance or ACE-MIRT era performance of the Booster. PIP-II era operations of the Fermilab proton complex will require the Fermilab Booster to increase beam intensity from 4.5e12 to 6.5e12 protons, while also increasing its ramp from 15 Hz to 20 Hz. These changes pose particular challenges for transition-crossing in the Booster, where longitudinal beam quality must be controlled in order to facilitate slip-stacking in the Recycler Ring later in the Main Injector cycle. Two novel gammaT jump schemes are proposed, termed “double gammaT jump” and “partial gammaT jump”, which optimize the magnitude of the gammaT jump within optics and power supply constraints.

Speaker: Jeffrey Eldred (Fermi National Accelerator Laboratory)

16:00 Isochronous induction cell storage ring

A challenge in realizing a steady-state microbunching (SSMB) light source is achieving a high average current from a stored beam with a peak current low enough to avoid collective effects that spoil the longitudinal phase space. We plan to investigate resolving this challenge by combining recent advances in isochronous transport and induction cells. The recently commissioned SLS-2 upgrade uses an anti-bend arc cell to control dispersion and reduce emittance.  We use this anti-bend design to yield an arc whose R56 can be adjustable to near-zero on a per-arc basis. This fine control of momentum compaction allows for better mitigation of effects that spoil the longitudinal phase space.  A consequence of RF technology, which most ring-based light sources use, is that high average current can only be achieved by pushing peak current, as only 1-2% of the circumference actually stores current.  High peak current drives other design considerations which result in a fast churning of the longitudinal phase space.  A ring with low peak current to avoid this churning has an average current too low to make a useful SSMB light source.  Induction cells with a reset time of ~10 ns have recently been developed for cinematographic radiography.  An induction cell could allow over 95% of the ring to store current, yielding a high average current and low peak current.  Here we outline an investigation to explore the beam dynamics and technology of such an isochronous induction cell storage ring.

Speaker: Mei Bai (SLAC National Accelerator Laboratory)

16:00 LAMP Front-End RFQ optimization for micropulse production

The LANSCE Modernization Project (LAMP) aims at upgrading the front end of the LANSCE accelerator, involving one single radio-frequency quadrupole (RFQ) at 201.25 MHz for simultaneously accelerating both proton (H+) and negative hydrogen ion (H-) beams from 100 keV to 3 MeV. To meet the diverse set of beam requirements at various user stations, the RFQ must be capable of accelerating a continuous-wave beam as well as a pulsed input beam. For example, with H- beam production, the RFQ accelerates a continuous-wave-like beam for the Lujan Center, and a pulsed beam for the Weapons Neutron Research (WNR) facility. The WNR operational mode is the highlight of the LANSCE accelerator and of the LAMP upgrade. We introduce the design optimization of the RFQ for ensuring that all associated requirements of the LAMP key performance parameters are satisfied. The optimization of the overall configuration of the low energy beam transport (LEBT) beamline for shaping the phase spaces of the WNR beam pulse at the entrance to the RFQ is also addressed.

Speaker: Haoran Xu (Los Alamos National Laboratory)

16:00 Leveraging the capabilities of LCLS-II: linking adaptable photoinjector laser shaping to tailored X-ray production

SLAC’s LCLS-II is pioneering high-repetition-rate attosecond X-ray science, enabling new opportunities to optimize X-ray generation by controlling the electron beam at its source—the photoinjector. LCLS-II employs a 20 ps Gaussian UV laser pulse to drive the photocathode, with an added narrow modulation to induce microbunching for extended modes. Recent advances in laser pulse shaping and frequency upconversion now allow for more sophisticated tailoring of the electron beam at the injector.
We present a novel approach using spectral amplitude and phase shaping of the IR laser, followed by dispersion-controlled nonlinear synthesis—relying on phase-modulated noncollinear sum-frequency generation—for UV upconversion. This enables diverse UV temporal profiles, including flattop and double/triple spikes, offering new degrees of freedom for shaping. Preliminary results from LCLS-II beam time show these modulations produce effective downstream perturbations to the electron bunch at the undulators, demonstrating feasibility for programmable bunch formation.
We are integrating this shaping into a start-to-end simulation framework,** enabling digital twin modeling of the XFEL chain—from photoinjector laser to X-ray output—laying the groundwork for fully tunable, end-to-end optimized, application-specific X-ray pulses.

Speaker: Jack Hirschman (Stanford University)

16:00 Longterm sustainment of electron beam linac systems for e-beam sterilization application

Fisica ATI has delivered turnkey e-beam linac sterilization systems for over three decades. The first installation was in 1992 under the Titan Beta. In 2000, SureBeam was established. Following its acquisition by L3 in 2005, the e-beam product line was consolidated under ATI. ATI continues to deliver high-reliability, fully integrated e-beam solutions for industrial and commercial applications as a division of Fisica. Our systems are engineered for continuous-duty (24/7), with >30 systems installed worldwide collectively logging >1million hours, with some systems in service for >20 years — demonstrating exceptional uptime and long-term durability. ATI provides comprehensive post-sales support, spare parts supply, and system upgrades. In 2024, we introduced a major enhancement: upgrading legacy 10 MeV 15/18 kW systems to 25 kW output—without altering the existing system footprint or significant changes to the major subsystems. This allows current customers to significantly boost throughput without the need for major facility modifications. The upgrade leverages the proven reliability of the existing e-beam sterilization subsystems.

Speaker: Yoko Parker (Fisica Inc. - Applied Technologies Inc.)

16:00 Low Energy Accelerator Development Facility upgrades

The Low Energy Accelerator Development (LEAD) Facility * is a part of the Accelerators Facilities Division (AFD) of the Brookhaven National Laboratory (BNL). The facility has three capabilities and runs a program specifically targeting new collaborations for user-driven research. The first and the oldest of the capabilities is the Ultrafast Diffraction (UED) Capability. The other two are radiation-shielded bunkers.
At the UED the deployment of a new stable solid-state modulator and klystron is in progress. The beamline updates are now going into place for a NASA Jet Propulsion Laboratory ** electron irradiator beamline for Single Event Effects (SEE) testing; and the capability for UED testing is being expanded.
In both bunkers (153 and 77 sq. m) a range of cooling, air, electrical, and RF capabilities are presently being introduced. The first bunker will accommodate the Electron Cyclotron Resonance *** (eCRA) Demonstrator (a project together with Omega-P, R&D). The deployment is expected to start in the last quarter of 2025. The second bunker will accommodate the superconducting radiofrequency (SRF) photo-gun **** (a project by Euclid Techlabs, LLC) to be the electron beam source for an envisioned Ultrafast Electron Microscopy (UEM) Capability.

Speaker: Anusorn Lueangaramwong (Brookhaven National Laboratory)

16:00 Measurements of single-shot attosecond X-ray pulses at high repetition rate

Electron dynamics in molecules occur on attosecond timescales and drive fundamental processes such as photosynthesis, catalysis, and chemical bond transformations. Understanding these phenomena requires tools with both high temporal resolution and the capability to probe molecular dynamics at high repetition rates. Here, we present the first single-shot measurements of attosecond soft x-ray pulses at the superconducting LCLS-II accelerator. Using an angle-resolving electron time-of-flight spectrometer, we perform angular streaking measurements with high energy and angular resolution, enabling a complete reconstruction of the spatial and temporal profiles of the pulses. These measurements showcase the attosecond science capabilities of LCLS-II at unprecedented repetition rates and provide the foundation for controlling and shaping x-ray pulses to study ultrafast dynamics in complex systems with precision.

Speaker: Veronica Guo (Stanford University)

16:00 Measuring orbit responses with oscillating trajectories in the Fermilab Linac

Recording changes in beam transverse positions and longitudinal phase reported by Beam Position Monitors (BPMs) in response to a beam deflection by an upstream dipole corrector or RF cavity phase (orbit response) is a powerful tool for analysis of accelerator optics and assisting with machine tuning. In Fermilab Linac, orbit responses were recorded by oscillating the corrector currents and cavity phases in a sinusoidal manner parasitically during regular operation, simultaneously oscillating up to 19 correctors and 7 cavities at distinct frequencies, providing faster, drift-resistant measurements through frequency-domain analysis. This report describes the technique, including error estimations and consistency checks and shows examples of the measurements.

Speaker: Alexander Shemyakin (Fermi National Accelerator Laboratory)

16:00 Mitigating transition in the Fermilab Booster using a triple phase jump

The PIP-II project currently under construction will boost neutrino production for DUNE, Fermilab's flagship long baseline neutrino oscillation experiment, by doubling the beam power delivered by the accelerator complex. To accomplish this, the total charge injected from the linac into the existing Booster RCS ring will increase from 4.5 to 6.5E12 while the machine ramp rate will be raised from 15 to 20 Hz.
The Booster accelerates beam from 800 to 8000 MeV and crosses transition at $\gamma = 5.45$ In current, pre PIP-II operations, no formal gamma-t jump system is used and the longitudinal emittance blowup is limited with an active quadrupole mode feedback system. Due to the slip-stacking process used in the dowstream Recycler Ring to accumulate and increase bunch intensity, to prevent excessive particle loss the longitudinal emittance at extraction limited is set to 0.1 eV-s (95\%). Given that collective fields scale with intensity, it is anticipated that additional measures will need to be put in place to meet this requirement. We look at the so-called triple phase-jump technique a possible candidates for transition mitigation and present some simulation results. Despite known limitations, attractive aspects of the triple jump are that the phase manipulations are incorporated within the digital LLRF system; no additional magnets or pulsed power supplies are needed and the technique is compatible with active quadrupole mode feedback.

Speaker: Jean-Francois Ostiguy (Fermi National Accelerator Laboratory)

16:00 Multi-GeV FFA beam transport test at CEBAF

Jefferson National Lab plans an upgrade project to reach 22 GeV high polarization electron beam by using Fixed Field Alternating-gradient (FFA) magnets. The utilization of the FFA magnets for 10-22 GeV beam energy range is unexampled, therefore those magnets need an experimental validation before their full installation to form an arc in the Continuous Electron Beam Accelerator Facility (CEBAF). For this reason, JLAB is also considering the design of an FFA magnet test bench, i.e. a half or full FFA cell, that would be deployed in the current CEBAF in order to serve as the highest energy demonstration for the FFA field uniformity, permanent magnet resiliency with the beam as well as enabling beam optics measurements with the 5-11 GeV range highly polarized beams which closely resembles the full energy range of the 22 GeV upgrade. In this report, we present the status of the planned beamline for the FFA beam transport test at CEBAF.

Speaker: Salim Ogur (Thomas Jefferson National Accelerator Facility)

16:00 Optimization of kicker location for pseudo single bunch operation in SPEAR3

The Pseudo Single Bunch (PSB) operation mode is being developed at Stanford Synchrotron Radiation Lightsource (SSRL) to address growing interests from time-resolved experiments. To accommodate both regular user and timing user experiments simultaneously, a fast electron kicker will be installed in one of the long straight sections at SPEAR3. This kicker will provide a large spatial separation between the main bunch trains and the camshaft bunch. The resulting x-ray spatial separation from undulator beamlines will be highly dependent on the location of the PSB kicker to be installed. We present here considerations of the PSB kicker location with beamline simulations for both low and high repetition rate modes.

Speaker: Dr Peifan Liu (SLAC National Accelerator Laboratory)

16:00 Orthogonal directions constrained gradient method for beam optics correction

An Orthogonal Directions Constrained Gradient Method (ODCGM) has been developed and experimentally used for optimization and correction of H$^-$ optical beam parameters for laser assisted charge exchange injection (LACE) experiments. LACE experiment requires precise tune up of H$^-$ beam parameters for high efficiency stripping. High precision tuning of beam parameters cannot be done in one step due to miscellaneous errors of power supplies and other factors. Then, subsequent application of the optic correction method considered here can do fine tune up of the beam. A simple experimental demonstration of ODCGM is presented.

Speaker: Timofey Gorlov (Oak Ridge National Laboratory)

16:00 Performance requirements for the LANSCE Accelerator Modernization Project

The LANSCE accelerator concurrently accelerates two beam species, H+ and H-, and delivers beam to five distinct user stations, including slow and fast neutron scattering centers, ultra-cold neutron research, proton radiography, and isotope production. The LANSCE Accelerator Modernization Project (LAMP) will replace the initial sections of LANSCE, from sources through the end of the 100-MeV drift-tube linac. The combination of multiple user stations, and the unique operation of LANSCE, present unique challenges and opportunities. In this paper, we present the performance requirements for LAMP, an overview of the project status and timeline, an overview of the conceptual design, and outlook.

Speaker: Dr John Lewellen (Los Alamos National Laboratory)

16:00 Photon stimulated desorption beamline at NSLS-II

Understanding synchrotron induced gas desorption plays an important role in predicting vacuum behavior of accelerators. Investigations of new materials and coatings require careful study of their desorption yield for potential use in upgrading NSLS-II as well as other accelerator facilities. A beamline at NSLS-II, dedicated to the study of novel and proposed vacuum materials has been constructed and commissioned to advance further research into desorption behavior. The PSD of stainless steel, OFHC copper and NEG coated copper, some of which for use in the future Electron-Ion Collider at BNL, have been measured and will be presented. These newly established desorption rates will be used as inputs to advanced modeling tools such as MolFlow+ and SynRad+ for accurate predictions of vacuum behavior and design optimization. The existing layout and future plans for the beamline will be presented.

Speaker: Robert Todd (Brookhaven National Laboratory)

16:00 Physics model to study resonant compton scattering

Over the past several decades, the elastic interaction between photons and electrons known as Compton scattering, has been the foundational mechanism for generating high-energy photon beams, particularly in the gamma-ray regime. Resonant interactions between photons and atomic systems offer significantly enhanced resonant cross-sections, often several orders of magnitude greater than what is achievable through conventional Compton scattering of electron and photon beams. The Gamma Factory initiative at CERN aims to exploit this enhancement by employing ultra-relativistic, partially stripped ion beams to generate high-intensity gamma-ray beams. In this work, we first examine the energy-matching requirements for resonance. We then present a semi-classical model based on a damped-driven oscillator to describe resonant Compton scattering. This model provides physical insight into the resonant cross-section and the limitations imposed by beam-beam interactions. We also propose a framework for simulating the scattering process.

Speaker: William Delooze (Duke University)

16:00 Radioisotope production at SNS (RIPS)

A unique opportunity exists to investigate alternative radionuclide production technologies utilizing the high-energy proton beams available at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The Second Target Station (STS) is being built to address emerging science challenges in energy, security, and transportation. The STS will complement the capabilities of the First Target Station (FTS) and High Flux Isotope Reactor (HFIR) by filling gaps in materials research that require the combined use of intense, long-wavelength (cold) neutrons, and instruments that are optimized for exploration of complex materials. The construction of the STS beamline to the target also presents an opportunity to capitalize on additional applications, such as the production of high-demand radioisotopes for medical applications.
Work began in 2024 to investigate the possibility of Radioisotope Production at SNS (RIPS) through four main goals: (1) identification of isotopes of interest through the modeling and simulation of prospective irradiation parameters and target compositions, (2) development of a target design concept that can receive high energy beam pulses from the SNS accelerator, (3) identification of enhanced isotope separation methods for SNS produced radionuclides, and (4) a design concept for an experimental/demonstration facility. An overview of the project and progress towards achieving these goals will be presented.

Speaker: Justin Griswold (Oak Ridge National Laboratory)

16:00 Radioisotope production at the Spallation Neutron Source: Design concept of experimental target station

Completion of the Proton Power Upgrade Project for the Spallation Neutron Source (SNS) accelerator at Oak Ridge National Laboratory opens an opportunity to utilize reserve beam power of more than 100 kW for applications beyond neutron production. One of these applications is the production of critical radionuclides. To demonstrate the feasibility of using the reserve beam power to produce radioisotope at SNS, a design concept of a small-scale experimental target station in the Linac Dump area has been developed. This experimental facility will provide isotope yield benchmarking data using protons in the GeV range. It will also enable additional research and development in isotope handling and radiochemical separation. The target station consists of a target module enclosed in a vessel and concrete shielding. Particle transport calculations and thermo-mechanical simulations are used to determine beam parameters, decay time, isotope yield, shielding dimensions, and target design parameters. Calculations verified that the irradiated capsule can be handled manually using hands-off tools and transported to a hot cell in a shielded container for post-irradiation characterizations.

Speaker: Yong Joong Lee (Oak Ridge National Laboratory)

16:00 Radioisotope production at the Spallation Neutron Source: Design concept of isotope production target

Upon completion of the Second Target Station (STS) Project in the mid 2030s, the Spallation Neutron Source accelerator at Oak Ridge National Laboratory will deliver a 2.7 MW proton beam to the neutron production targets. In the post-STS phase, the accelerator will have a reserve beam power capacity of at least 100 kW beyond what the two neutron production targets will receive, which could potentially be ramped up to 300 kW. In this paper, a design concept for a radioisotope production target that could utilize 250 kW of the reserve beam power capacity is presented. The target consists of thorium discs encapsulated in 316L austenitic steel shells that are cooled by water. The estimated post-irradiation activity of Ac-225 and Ra-225, critical medical radioisotopes used in targeted alpha therapy cancer treatment, is calculated at the end of bombardment after a 14 day long irradiation time. Thermal and structural analyses are performed on the basis of calculated nuclear heating data. The technical feasibility of a high-power target under a 250-kW beam load with an extremely low duty factor of $3.5\cdot 10^{-6}$ is presented from thermal, structural and fatigue lifetime perspectives.

Speaker: Yong Joong Lee (Oak Ridge National Laboratory)

16:00 Recent progress on CsTe photocathode growth at LANL

This poster will discuss the performance of CsTe photocathodes recently grown for the CARIE (Cathodes and Radiofrequency Interactions in Extremes) project at LANL. CARIE requires a low emittance, high quantum efficiency (QE) photocathode, capable of withstanding challenging vacuum conditions and high fields. CsTe is a natural fit. We will describe recent efforts to optimize the co-deposition process after our growth chamber was rebuilt from contamination. We will also show our study of QE from CsTe on different substrates.

Speaker: Haoran Xu (Los Alamos National Laboratory)

16:00 Research program at the NLCTA Test Facility

The research program at the NLCTA Test Facility at SLAC National Accelerator Laboratory includes experiments spanning a broad range of applications, from accelerator technology for HEP to applications in medicine, industry, and national security. The test areas utilize the infrastructure of the original Next Linear Collider Test Accelerator (NLCTA) including high power RF sources at X-band (11.424 GHz) and S-band (2.856 GHz) and a radiation shielded vault designed for a 1 GeV electron beam. The X-band Test Accelerator (XTA) delivers electron beam at energies from 30-70 MeV and up to 100 pC. NLCTA is participating in the new BeamNetUS network of test facilities. NLCTA facility capabilities include cryogenic testing down to 4 K with high power RF, electron beam and laser at 800 nm on XTA, and a planned test area for high magnetic fields.

Speaker: Emma Snively (SLAC National Accelerator Laboratory)

16:00 Simulation of the thermoelectric effect in a multi-metallic superconducting cavity

Superconducting radio-frequency accelerating cavities made with different material layers, such as copper, Nb or Nb₃Sn, are susceptible to thermoelectric effects due to differences in Seebeck coefficients between the metals. A temperature gradient across the surfaces can drive thermoelectric currents, which may impact the cavity performance. A layered Cu/Nb/Nb3Sn single-cell cavity was tested with cryocoolers in 2022. Three heaters were mounted on the cavity surface at different locations and three single-axis cryogenic fluxgate magnetometers were attached close to the cavity equator. A linear increase in the magnetic field was measured while increasing the heaters' power. The cavity setup was analyzed with COMSOL and the results showed a trend similar to that observed in the experiment. This contribution details the approach chosen for the simulation and some of the challenges encountered.

Speaker: Nabin Raut (Thomas Jefferson National Accelerator Facility)

16:00 Simulations of positron injector for Ce+BAF

A baseline concept for a continuous wave (CW) polarized positron injector was developed for the Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. This concept is based on the generation of CW longitudinally polarized positrons by a high-current, polarized electron beam (1 mA, 130‑370 MeV, and 90% longitudinal polarization) that passes through a rotating, water-cooled, tungsten target. The simulation results for the Ce+BAF injector at the Low Energy Recirculator Facility (LERF) are presented, including positron beam generation, capture, energy selection, and acceleration to 123 MeV. The positron yield (or positron current) and longitudinal polarization are calculated considering the longitudinal and transverse CEBAF acceptances (<1% energy spread, <1 mm bunch length and normalized emittance of <100 mm mrad). The impact of target thickness, drive electron beam energy, and transverse size on positron yield within the required emittance limit is evaluated.

Speaker: Andriy Ushakov (Thomas Jefferson National Accelerator Facility)

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 progress towards characterization of the pulses 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 Single-shot longitudinal phase-space measurement of thermionic-cathode gun beam at the APS linac*

Advancements in particle accelerator technology hinge on our ability to precisely measure and understand the behavior of high-brightness beams. Following the installation of the new photo-cathode gun (PCG) laser at the front-end of the Advanced Photon Source (APS) linac, commissioning studies are needed to understand and bring the new PCG beam up to operational standard. In the present work, we present initial measurements characterizing the longitudinal phase-space of the thermionic-cathode gun (TCG) electron beam using a transverse deflecting cavity (TCav) located at the end of the APS linac. Downstream of the TCav, which deflects the beam vertically, lies the B1 horizontal bending magnet and three Chromium Oxide screens placed at three different locations where the beam is intercepted and imaged. Measurements of the TCG beam longitudinal phase-space are discussed and compared to previous measurements of the PCG beam longitudinal phase-space.

Speaker: Timothy Suzuki (Michigan State University, Argonne National Laboratory)

16:00 SLAC MeV ultrafast electron diffraction facility upgrade plans

Mega-electronvolt ultrafast electron diffraction (MeV-UED) is a complementary tool to X-ray based instruments that has enabled ground-breaking studies in condensed matter physics and chemical science. The SLAC MeV-UED facility uses a state-of-the-art 1.6-cell RF photoinjector to deliver 3 to 4 MeV electrons for a variety of pump-probe studies in solids, liquids, and gases, with over 6600 delivered hours and >87 publications since 2021. To broaden the scientific opportunities, facility expansion and enhanced instrument performance of MeV UED have been heavily requested. We discuss near and long-term plans for upgrade and expansion of MeV-UED, with anticipated improvements in beam delivery, system performance, data acquisition, and temporal and momentum-space resolution.

Speaker: Robert England (SLAC National Accelerator Laboratory)

16:00 Spectrotemporal shaping of attosecond x-ray free-electron laser pulses

X-ray free-electron lasers have opened new frontiers in attosecond science thanks to their high pulse energy compared to traditional table top sources. To date, most attosecond experiments performed at XFELs have been impulsive, with the impinging x-ray pulses being much shorter than the timescales being studied. We present a method for attosecond pulse shaping which enables us to move beyond simple observation of ultrafast dynamics towards coherent control of quantum systems on sub-femtosecond timescales. We present experimental evidence of phase locked attosecond pulse trains from the LCLS-II. We conclude by presenting recent experiments utilizing mutually coherent pulse pairs with controllable temporal and spectral delay to launch controllable coherent electronic wavepackets in molecular systems.

Speaker: River Robles (Stanford University)

16:00 Spin-transparent storage rings for quantum computing

Spin-transparent storage rings, where any spin direction repeats after one full turn, can be used in conjunction with ion traps as a new quantum computing platform [1]. Advantages of spin-transparent rings for quantum computing include: large numbers of stored qubits; long quantum coherence times of up to several hours; long storage lifetimes; and room temperature operation. These exceptional qualities mean rings could provide a scalable way to implement algorithms with deep complexity requiring many quantum operations while simultaneously providing a large number of qubits. This new platform where the qubit has long quantum coherence time can also be used as a quantum sensor or a part of a quantum memory.

Speaker: Riad Suleiman (Thomas Jefferson National Accelerator Facility)

16:00 Status of MicroBeam Linatron (MBL) product line development at Varex Imaging Corporation

The High Energy Systems (HES) group at Varex Imaging Corporation (Varex) introduced a new concept and design for Accelerator Beam Centerline (ABC) (patent pending), which can be used on compact commercial electron linear accelerators in 1-20 MeV energy range, delivering substantially reduced, less than 0.5 mm focal spot on a beam stopping target in order to improve imaging qualities with the produced Bremsstrahlung. The first 6 MeV prototype tests have been completed successfully, and the work continues to build and test a 3 MeV and 9 MeV ABC prototypes. These linac systems received a brand name MicroBeam Linatron (MBL) series. The design and experimental data obtained up to date are presented.

Speaker: Dr Andrey Mishin (Varex Imaging (United States))

16:00 Steady-State Microbunching using Optical Stochastic Cooling

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 2026 and will incorporate an optical amplifier to enable significantly 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 a free-electron laser 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 integration of OSX development as part of the OSC program at IOTA. The design of an accelerator lattice to enable the mechanism and associated high fidelity simulations demonstrating the beam dynamics will be shown, and a path to realizing an experimental demonstration will be discussed.

Speaker: Michael Wallbank (Fermi National Accelerator Laboratory)

16:00 Study of nonlinear beam dynamics of an asymmetric NSLS-II lattice

NSLS-II is planning an upgrade to an ultra-low emittance storage ring using a novel lattice concept, the complex bend, composed of combined-function magnets. To evaluate technical challenges and study beam dynamics with complex bend, two bending magnets of existing NSLS-II bare lattice are proposed to be replaced with complex bends, introducing lattice asymmetry. To study the impact of asymmetry on NSLS-II bare lattice, an asymmetric lattice is developed by adjusting quadrupole triplets in the Cell 8 long straight section. This paper presents the modified linear optics, optimization of nonlinear dynamics, and a comparison with the nominal bare lattice. The optimized asymmetric bare lattice is also experimentally measured in the machine, and dynamic aperture measurements are reported.

Speaker: Minghao Song (Brookhaven National Laboratory)

16:00 The APS linac RF station upgrading status

The Advanced Photon Source (APS) linac has reliably delivered high-quality electron beams for over 30 years. To support the APS Upgrade and ensure continued operation, a major refurbishment is underway. As part of this project, two of the linac's five operating radio frequency (RF) stations have been upgraded with solid-state modulator-powered klystrons and new digital low-level radio frequency (LLRF) systems. This upgrade has notably improved the linac's performance. This paper summarizes these improvements and outlines our next plans.

Speaker: Yawei Yang (Argonne National Laboratory)

16:00 The LANL Proton radiography Facility and Near-Term Improvements

The proton radiography facility at LANL (pRad) performs multi-frame, dynamic radiography of dense materials up to 50 g cm$^{-2}$ with interframe timing down to 100 ns. The multiple Coulomb scattering of protons and the use of magnet optics allows for precise areal densities, and in experiments with radial symmetry, volume density reconstructions. The temporal structure of the Los Alamos Neutron Science Center (LANSCE) 800-MeV proton beam allows flexibility for multi-frame imaging over the duration of dynamic processes lasting up to 20 µs or more. The LANL pRad facility routinely provides valuable data characterizing high explosive detonation and materials under strain. However, it is limited by chromatic effects that effectively limited the ultimate thickness and dynamic range of an experiment, making thin materials and subtle changes hard to visualize. Work currently underway aims to eliminate or mitigate these issues. This talk aims to familiarize the community with pRad’s current capabilities and the work going
on to improve our radiography and expand the range of possible experiments with futureupgrades to the pRad beamline and LANSCE.

Speaker: John Schmidt (Los Alamos National Laboratory)

16:00 The Los Alamos Neutron Science Center (LANSCE) Accelerator: Current Condition and Status of Modernization Efforts

The Los Alamos Neutron Science Center (LANSCE) accelerator is MW-class H-/H+ 800 MeV linear accelerator that serves five distinct user facilities that support Los Alamos National Laboratory (LANL) national security missions, commercial applications, and the Department of Energy’s Office of Science medical isotope production program. After more than 50 years of continuous operation, we are embarking on upgrades of major accelerator systems in order to continue LANSCE operations for several more decades. We will present an update on the status of the accelerator today and our modernization efforts.

Speaker: Steven Russell (Los Alamos National Laboratory)

16:00 The potential high orders of vertical electric field systematic effect due to hyperbolic/elliptical deformed electrode plates in the proton-EDM ring

To achieve high precision in a storage ring experiment, it is essential to eliminate field errors up to a certain order to ensure they do not contribute to systematic effect to the experiment. In this study, we modeled electrode plates of electrostatic deflector with hyperbolic/elliptical shape deformation schemes. We analyzed the resulting beam dynamics and spin effects caused by these higher-order electric field errors and explored the potential systematic effects introduced by such deformed electrostatic deflectors within the proton Electric Dipole Moment (pEDM) Symmetric-Hybrid ring design*.

Speaker: Bhawin Dhital (Brookhaven National Laboratory)

16:00 The Reconfiggler: A uniquely versatile wiggler

Wigglers are periodic arrays of magnets with myriad applications in accelerator physics. Generally though, they are only tunable by adjusting the gap between jaws. Here, we present a wiggler based on diametrically magnetized cylindrical magnets with independently adjustable angle. This allows the realization of arbitrary (bandwidth constrained) magnetic configurations. We illustrate its application to the recently proposed "transverse wiggler" concept for transverse phase space control.

Speaker: Nathan Majernik (SLAC National Accelerator Laboratory)

16:00 Time-of-Flight energy measurements with BPMs

The energy of a bunched non-relativistic ion beam can be deduced from measuring the beam phases in neighboring Beam Position Monitors (BPMs). This report presents estimations on implementation of such a procedure at PIP-II H- linac being constructed at Fermilab. In part, the case when the flight time between BPMs is larger than the period of BPM frequency is considered in detail. When the absolute BPM phase calibration is not available, the BPM phase information can be used to trace deviations of the beam energy from the desired value. Such “energy deviation” parameter is operationally implemented at the transfer line between 400 MeV Linac and the Booster, and its analog is expected to be used in the transfer line from PIP-II as well.

Speaker: Alexander Shemyakin (Fermi National Accelerator Laboratory)

16:00 Transport Lattice Optimization for an S-Band Compact Electron Linear Accelerator

We present an optimization of a novel compact accelerator configuration, where each accelerating cell is individually driven by an emerging high-power, solid-state RF amplifier. This architecture, first developed at LANL for space applications, has the potential to produce a high-power electron beam with reduced footprint. Optimizing the size, weight, and cost of construction and operation of such an accelerator, while ensuring redundancy, requires a detailed particle simulation model. In this work, the design of a 2 MeV compact electron linac with 1.5 kW average beam power was optimized using a simulation model of the linac created using the software package General Particle Tracer (GPT). The accelerator consists of a 20 kV DC electron gun, a pre-buncher cavity and five 4-cell modules containing S-band cavities that accelerate the beam to 2 MeV, as well as provide transverse focusing. Additional transverse focusing is provided by solenoids along the beamline to maximize transmission. The cavity phases and the solenoid currents were optimized to maximize transmission through the accelerator. The design of the compact electron linac and its optimization will be presented at the conference.

Speaker: Joshua Yoskowitz (Los Alamos National Laboratory)

16:00 Transport of 12 GeV positron beams at Ce+BAF

Jefferson Lab (JLab) is developing a concept to upgrade the Continuous Electron Beam Accelerator Facility (CEBAF) to additionally deliver spin-polarized continuous-wave positron beams for its nuclear physics program users (Ce+BAF 12 GeV). The concept involves repurposing the Low Energy Recirculator Facility (LERF) at JLab as a dual injector, first producing 100-300 MeV spin-polarized electron beams which are subsequently used for the generation and formation of 123 MeV continuous-wave positron beams. The positron beams are transported to CEBAF and injected for acceleration up to 12 GeV, tailored to the requirements of its four experimental halls. Given the higher emittance of the secondary positron beams, the CEBAF optics are optimized for low dispersion and low beta functions to enhance transmission within the Ce+BAF acceptance limits and with an R56 to manage the positron beams bunch length and energy spread. Potential bottlenecks are being investigated through both optical modeling and measurements using an electron beam, as well as degraded electron beams, to map the 6d acceptance of CEBAF as it is today. This presentation shares preliminary results from multi-particle tracking simulations of the positron beam up to 12 GeV, including spatial, momentum, and spin characteristics, and explores the feasibility of delivering beams simultaneously to multiple experimental halls via extraction optics.

Speaker: Salim Ogur (Thomas Jefferson National Accelerator Facility)

16:00 Traveling-wave chopper structures for LANSCE modification project

The Los Alamos Neutron Science Center (LANSCE) accelerator complex delivers both protons and negative hydrogen ions with various beam time patterns simultaneously to multiple users. The LANSCE linac front end is still based on Cockcroft-Walton voltage generators. An upgrade of the front end to a modern, RFQ-based version – a part of the LANSCE Modernization Project (LAMP) – is now in the conceptual design stage. The LAMP will need fast beam choppers both in the low-energy transport (LEBT, 100 keV) before RFQ, and in the medium-energy transport (MEBT, 3 MeV) after RFQ. We use CST modeling to develop fast traveling-wave current structures for LAMP MEBT and LEBT beam choppers. A few structure types: plate-coax helix, meander-folded stripline on high-dielectric-constant substrate, and double-helix – are considered and compared. The structures must provide short rise / fall times of the deflecting electric field (1-ns class in MEBT), while still making possible for the chopper pulse generators to deliver the required voltages at high repetition rates.

Speaker: Sergey Kurennoy (Los Alamos National Laboratory)

16:00 Tunable Terawatt Attosecond Soft‑X‑Ray Pulse Pair from a Plasma Wakefield Driven Free Electron Laser

Attosecond X-ray pulses are a pioneering tools for real-time observation of ultrafast electronic dynamics in atoms and molecules, opening up revolutionary advances in chemistry, materials science, and condensed-matter physics. Existing attosecond sources are, however, constrained by low photon energy and flux, which limits their experimental applications. we present here start-to-end simulations of soft-X-ray FEL, taking advantage of attosecond electron beam generated from PWFA to provide terawatt-level peak power in pulses of merely tens of attoseconds duration. High-brightness electrons produced in PWFA are longitudinally compressed in a magnetic arc and then injected into an undulator. By tuning the undulator taper, two isolated spikes of radiation—each tens of attosecond duration and terawatt peak power are generated for inherent pump–probe application with tunable delays. Such an ultraintense, ultrashort source offers a direct route to table-top X-ray light sources and facilitates attosecond-resolution experiments with unprecedented intensity and time resolution.

Speaker: Xuan Zhang (Stony Brook University)

16:00 Tuning of a force-neutral adjustable-phase undulator

We present a hybrid permanent magnet-based adjustable phase undulator, featuring a period length of 17.2 mm, a gap of 8.5 mm, and a total length of 2.4 m. This planar polarized undulator adjusts field intensity through longitudinal jaw movement, with mechanically linked magnet arrays ensuring smooth motion. Building on previous work, this report focuses on newly developed tuning techniques for trajectory and phase error correction. Our engineering experience demonstrates the effectiveness of these methods in optimizing undulator performance.

Speaker: Maofei Qian (Argonne National Laboratory)

16:00 Ultra-Bright Cavity-Based X-ray Free Electron Lasers

Cavity-based X-ray Free electron lasers (CBXFELs) such as the X-ray regenerative amplifier FEL (XRAFEL) and the XFEL oscillator (XFELO) have been proposed to produce highly coherent and stable hard X-rays. While the XRAFEL produces high-peak power X-rays with the bandwidth limited by the Bragg crystals, XFELO produces much lower peak power with extremely narrow bandwidth. In this report, we discuss methods to increase the CBXFEL peak power and reduce the bandwidth altogether. We show in simulations how these methods can be applied to high-repetition rate FEL facilities to generate ultra-bright X-ray pulses.

Speaker: Zhirong Huang (SLAC National Accelerator Laboratory)

16:00 Update on septum magnet redesign at LANSCE Proton Storage Ring

We report the progress of redesigning the septum magnet at the LANSCE Proton Storage Ring (PSR). The septum magnet at the PSR is used for extracting the accumulated 800-MeV proton beams for transport to the target stations. The existing septum magnet uses parallel, planar coils creating a uniform deflecting magnetic field. However, one coil plate co-locates with the septum; this placement results in the coil, witnessing intense radiation dose rates, receiving accumulated damage to the epoxy potting during the PSR operation. The redesigned septum magnet uses a ferritic steel septum, and the coils are positioned farther away from the proton beam pipes. This placement, combined with the adoption of a more radiation-resistant potting epoxy, is expected to reduce the dose rate on the coil pack, correspondingly increasing the operating lifetimes. The magnet pole tips are refined with shim features to provide a wide flat-field region. The mechanical engineering of the yoke components and the supporting structures is underway. Particle tracking simulations of the proton beam deflection in the septum magnet were performed, and the comparison of performance between the existing and the redesigned septum magnets is reported.

Speaker: Haoran Xu (Los Alamos National Laboratory)

16:00 Updates on scientific and R&D highlights at SLAC MeV-UED facility

Ultrafast electron diffraction using MeV energy beams (MeV-UED) has enabled unprecedented scientific opportunities in the study of ultrafast structural dynamics in a variety of gas, liquid and solid-state systems. The SLAC MeV-UED program began in 2014 and became an LCLS user facility in 2019. This work will review recent R&D efforts for enhancing the resolution, flux and electron detection of the MeV-UED instrument. Additionally, the integration of Al/ML techniques is being explored to optimize facility operations and accelerate scientific discovery. In all, these will open new avenues for explorations in key areas of ultrafast science.

Speaker: Fuhao Ji (SLAC National Accelerator Laboratory)

16:00 User research at BNL’s Accelerator Test Facility

The Accelerator Test Facility (ATF) at BNL is the DOE Office of Science User Facility for Accelerator Stewardship, featuring a high-brightness, 80-MeV electron LINAC, near-infrared (NIR) lasers at 1.06 and 0.8 µm, and a 5-TW, 2-ps long-wave infrared (LWIR) 9.2-µm laser. ATF is advancing LWIR laser technology toward the multi-terawatt, femtosecond regime—a major milestone in this spectral domain. Its unique suite of synchronized or independently operated capabilities enables breakthroughs across a broad range of studies, from materials science to Homeland Security, and from advanced radiation sources to novel methods of particle acceleration. Research priorities are shaped by community input through ATF User Meetings and Science Planning Workshops. A key focus is leveraging the co-location of the LINAC and “multi-color” lasers to place ATF at the forefront of THz to hard x-ray radiation sources, plasma physics, and advanced accelerator R&D. In this approach, the LWIR laser drives plasma dynamics, while the LINAC and NIR lasers enable ultrafast probing of plasma fields and density, or controlled electron injection into plasma wakes. These efforts support global research into plasma instabilities relevant to astrophysics and inertial confinement fusion, as well as the development of future colliders and compact accelerators with potential industrial applications. Recent ATF user results highlight these advances.

Speaker: Mr Marcus Babzien (Brookhaven National Laboratory)

16:00 Visualization tools for EGUN simulations

DC electron guns are essential sources of moderate-energy electron beams for both particle accelerators and klystrons. EGUN is one of the simulation software that is employed to design such DC guns. EGUN produces detailed data of electron rays trajectories for a given gun geometry, cathode temperature, bias-voltage, and beam current - whether space-charge limited or not. We use Mathematica and Python for advanced mathematical processing and visualization of the EGUN data visualization. For example, we generate phase-space plots at various longitudinal cross-sections and show the evolution of phase-space parameters along the beam axis. The visualization we generate is much richer than the simple trajectory plots generated by EPLOT software that accompanies EGUN. In this research work, we show the example of a practical Klystron gun and the results of our post-processing software.

Speaker: Katie Casey (University of Southern California, SLAC National Accelerator Laboratory)

18:00 → 21:30 Banquet

Bar opens at 6:00
Dinner at 7:00

Friday 15 August

08:00 → 09:00 Coffee

09:00 → 09:30 Colliders and other Particle and Nuclear Physics Accelerators (Invited)

09:00 Progress towards the US-based muon collider

A multi-TeV muon collider has the unique potential to provide both precision measurements and the highest energy reach in one machine that cannot be paralleled by any currently available technology. There has been significant physics interest on Muon Colliders recently as indicated by the formation of the International Muon Collider Collaboration but also the recent P5 report. This study describes a possible set of R&D and deliverables of the muon collider accelerator R&D program in the U.S. We describe high-priority studies to be performed in the first phase that will address critical questions for deciding the future plan for a muon collider design. The goal of these studies is to firm up choices for the most challenging components of a muon collider design, and to propose and begin testing and prototyping of components and systems that are needed to have confidence in and inform our specification choices. Key areas wherein the US can provide critical contributions to the newly formed international muon collider collaboration will be discussed as well.

Speaker: Diktys Stratakis (Fermi National Accelerator Laboratory)

09:00 → 09:30 Applications of Accelerators, Technology Transfer, Industrial Relations, and Outreach (Invited)

09:00 Novel high gradient normal conducting linacs and their applications

Recent SLAC research on novel design techniques for normal conducting accelerators has produced multiple new approaches to increase the gradient as well as the efficiency of these structures. Distributed coupling linacs, in which individual cells are fed through parallel power distribution manifolds, have enabled new flexibility in the optimization of the cell geometry to increase the accelerating gradient while constraining the local surface field enhancement to reduce susceptibility to breakdown. This innovation takes advantage of state-of-the-art high-power computing to fully model the linac, RF distribution network, and beam dynamics using tools like SLAC’s ACE3P modeling suite. Cold copper structures are another key example of the advances at SLAC where cryogenic operation has been shown to increase the shunt impedance and reduce the breakdown rate. SLAC is actively developing these techniques and pursuing new approaches, like driving structures with very short RF pulses. Design and simulation efforts are complimented by high power testing capabilities at the NLCTA Test Facility. SLAC is investigating applying these high gradient design advances to a wide array of accelerator applications spanning discovery science, medicine, and national security.

Speaker: Emma Snively (SLAC National Accelerator Laboratory)

09:30 → 10:30 Colliders and other Particle and Nuclear Physics Accelerators (contributed)

09:30 Xsuite Contributions to Modeling of Collective Effects in Present and Future Colliders: Synergies Between FCC and EIC

The design, optimization and possibly operation of future particle colliders such as the Future Circular Collider (FCC) and the Electron-Ion Collider (EIC) require advanced, flexible, and collaborative modeling frameworks to address complex collective effects in beam dynamics. Central to this effort for the FCC is Xsuite—a Python-based modular toolkit combining symplectic particle tracking with detailed models of synchrotron radiation, impedances, space charge, electron cloud, beam-beam interactions, and feedback systems. Xsuite’s contributions to FCC studies have been substantial, and its potential extension to EIC opens new avenues for collaborative research. This platform fosters international cooperation by enabling researchers across continents to share models, simulation results, and expertise seamlessly. Such synergy facilitates high-fidelity exploration of beam dynamics phenomena critical to machine performance, including beam collective effects and luminosity degradation, with computational efficiency on both CPU and GPU architectures. By harmonizing modeling efforts for FCC and EIC, the platform can contribute to a coherent understanding of beam dynamics across different collider designs. We discuss ongoing and potential progress in adapting and extending Xsuite for joint FCC and EIC studies, emphasizing the advantages of collaborative workflows and the transformative impact these tools can have on the design and operation of next-generation colliders.

Speaker: Tatiana Pieloni (École Polytechnique Fédérale de Lausanne)

09:50 Design of ring electron cooler

Electron cooling at high energy requires large average current in the cooling section (CS), which can be achieved by reusing the same electron beam on many passes through the CS. One of the options to realize this cooling scheme is to use an electron storage ring. In this paper we describe a conceptual design of the Ring Electron Cooler (REC), as a potential future application for the Electron Ion Collider. The REC uses 150MeV electrons to cool protons in hadron ring while electrons themselves are being cooled by radiation damping wigglers installed in electron storage ring. Design of the REC considers electrons’ space charge, an effect of proton-electron focusing, a beam-beam scattering in the CS and electrons’ intra-beam scattering in the storage ring, as well as other collective effects. In this paper we discuss the status of the REC design and describe multiparametric optimization involved in the design efforts.

Speaker: Sergei Seletskiy (Brookhaven National Laboratory)

10:10 Crabbing schemes for the Electron-Ion Collider

The Electron-Ion Collider (EIC), to be constructed at Brookhaven National Laboratory, will collide polarized high-energy electron beams with polarized proton and ion beams, achieving luminosities of up to 1 × 10^34 cm^−2 s^−1 in the center-of-mass energy range of 20-140 GeV. Crab cavities will be used in both EIC rings to compensate for the geometric luminosity loss due to the large crossing angle of 25 mrad in the interaction region. For the baseline design, a local crabbing scheme is adopted for both EIC rings, where crab cavities will be installed on both sides of the interaction region, and the ideal horizontal phase advance between the interaction point and the crab cavities is 90 degrees. In this article, we will study the feasibility of using a global crabbing scheme for each EIC ring, and, in particular, the case where the crab cavities in the Electron Storage Ring (ESR) will not be available during the early EIC commissioning. In this scenario, we need to reduce the electron beam's beam-beam parameter to avoid electron loss during injection.

Speaker: Yun Luo (Brookhaven National Laboratory)

09:30 → 10:30 Applications of Accelerators, Technology Transfer, Industrial Relations, and Outreach (Contributed)

09:30 First Beam Demonstration in Hand-Portable Battery-Operated Ku-band Split Linac

X-ray generators, producing radiation in the MeV range, are a critical tool for radiography, non-destructive testing, and security applications. The field operation of such source requires them to be hand-portable, autonomous, and allow parameter adjustability. The dramatic level of miniaturization and cost-reduction of electron linac is achieved thanks to the implementation of such innovative technologies as air-cooled Ku-band air-traffic control magnetrons, split accelerating structure fabrication technique, and solid-state Marx modulators. In this talk, we present the design and test results of a 2 MeV Ku-band electron linac for a hand-portable X-ray generator system for field radiography, being developed by RadiaBeam.

Speaker: Sergey Kutsaev (RadiaBeam Technologies (United States))

09:50 High-Precision Characterization of MeV Electron Interactions for Advanced Nano-Imaging of Thick Biological Samples and Microchips

The resolution of a MeV Scanning Transmission Electron Microscope (MeV-STEM) is mainly limited by the electron beam properties and angular broadening in thick biological samples and microchips. Addressing these challenges requires understanding beam emittance, optical aberrations, and energy-dependent scattering angles. We propose a standardized method to assess beam intensity, divergence, and size at the sample exit to better characterize electron-sample interactions, align analytical models, and validate Monte Carlo simulations. Our results show that accurately measuring parameters—especially angular broadening—is both feasible and essential for improving resolution. Using a high-energy (1–10 MeV) electron source and tailored beams, along with amorphous ice and silicon as sample proxies, we aim to optimize beam energy and focus for enhanced imaging. This is critical for in-situ imaging of thick biological samples and detecting nanometer-scale microchip defects. Ultimately, we aim to map the minimum electron energy needed for nanoscale resolution across varying sample types and imaging modes.

Speaker: Xi Yang (Brookhaven National Laboratory)

10:10 Progress in Advanced Ferroelectric Technologies for Fast SRF Cavity Tuning

In this talk, Euclid Techlabs, in collaboration with Jefferson Lab, Helmholtz-Zentrum Berlin (HZB), and CERN, will present recent advancements in ferroelectric material-based fast tuning systems for SRF cavities.
Currently, the most common approach to managing fast cavity frequency shifts is to over-couple the fundamental RF power, which results in significant power waste. Recent developments in ultra-low-loss ferroelectric materials have made ferroelectric-based tuning technology for SRF cavities a viable alternative. The Horizon Europe iSAS project focuses on improving accelerator efficiency and includes the integration of a ferroelectric fast reactive tuner (FE-FRT) to enhance energy conservation. Applications under this initiative include an FE-FRT for 400 MHz transient beam loading compensation in the LHC, FE-FRT systems for microphonics compensation in 1.3 GHz SRF cavities, FE-FRTs for energy recovery linac (ERL) applications, and retrofitting FE-FRTs into existing HL-LHC cryomodules*. In the U.S., FE-FRT technology is under active development for microphonics compensation in CEBAF and as a potential upgrade path for the Electron-Ion Collider (EIC), where it may serve as a dedicated hardware solution for active microphonics control in crab cavities.

Speaker: Alexei Kanareykin (Euclid Beamlabs)

10:30 → 11:00 Coffee

11:00 → 13:00 Friday Plenary

11:00 Physics with extreme beams at FACET-II

With today’s accelerator facilities such as the 10 GeV FACET-II facility at SLAC National Accelerator Laboratory, extreme beam physics is emerging as a promising science area where ultrashort and dense electron beams can be used as a source of TV/m fields, enabling high field matter interaction and new applications in photon science and particle acceleration. By delivering extreme beams with peak current reaching 100 kA and enabling its interaction with lasers, plasmas, and solids, FACET-II has a broad science program ranging from high-field plasma-based acceleration, laboratory astrophysics, extreme focusing and attosecond sources, FCC-ee studies and laser particle control and collimation for colliders, and probing quantum electrodynamics near the Schwinger critical field. After presenting an overview of the physics opportunities offered by the FACET-II facility, I will highlight recent breakthroughs achieved at FACET-II, such as the most precise measurements of quantum radiation reaction to date, the generation of 100-kA class beams by laser-electron beam shaping, the demonstration of a brightness and energy transformer, efficient plasma acceleration with percent-level field uniformity, wakefield mapping and probing, and extreme beam focusing by leveraging intense coherent transition radiation in the near field or plasma fields.

Speaker: Prof. Sebastien Corde (Laboratoire d'Optique Appliquée)

11:30 Accelerating Discoveries in Particle Physics

Particle accelerators have played a critical role in high-energy physics for many decades. They have facilitated the discovery of elementary particles at the smallest scales and the study of fundamental interactions at the highest energies. The increasing size and cost of these facilities have turned them into truly international projects. Next-generation accelerators will advance the frontiers of accelerator science through extensive R&D, develop new technical applications, and offer opportunities to discover new physics.

In this talk, I will describe the global process and planning efforts for the next large accelerators, with a particular focus on the recent Particle Physics Project Prioritization Process (P5) in the US and the European Strategy for Particle Physics Update. I will summarize the scientific opportunities and technical challenges, and outline the political and sociological difficulties associated with realizing such projects. I will conclude with a vision for the role of accelerators in the future of high-energy physics and beyond.

Speaker: Karsten Heeger (Yale University)

12:00 Ignition Achieved: Next Steps in the Path Toward an Inertial Fusion Energy Future

The achievement of ignition on the National Ignition Facility in 2022 demonstrated the fundamental feasibility of controlled thermonuclear fusion in the laboratory for energy gain, and was the first major hurdle in efficiently harvesting fusion energy through inertial fusion energy (IFE). Excitement has been growing worldwide, with notable activity in the public and private sectors. To make IFE commercially viable, however, there are still significant scientific, engineering, workforce, and economic hurdles. This talk will review the advancements that made the ignition breakthrough possible, provide an overview of the international IFE landscape, and describe the remaining gaps and challenges that must be solved to realize IFE laser inertial fusion as a path for clean energy and energy security.

Speaker: Tammy Ma (Lawrence Livermore National Laboratory)

12:30 Closing Remarks

Speaker: Tor Raubenheimer (SLAC National Accelerator Laboratory)

13:00 → 13:30 Closing NAPAC'25