THPM
-
Thursday Poster Session: THPM
05 Jun 2025, 15:30 -
17:30
THPM001
Magnetic field control in the MedAustron synchrotron
2687
MedAustron, a synchrotron-based ion therapy centre in Austria, is focused on enhancing cancer treatment performance. A key improvement opportunity lies in the regulation of the main ring bending dipoles, which currently require time-consuming procedures to ensure reproducibility and reliability of the associated magnetic fields (B-Fields). Other therapy centres globally address this through a traditional B-train or similar systems to regulate on the B-Field and mitigate parasitic effects. In contrast to that, we propose a novel approach utilising a single Hall probe measurement inside a reference magnet, fused with a magnet model to provide real-time, high accuracy estimates of the integral B-Field for regulation. This technique, combined with a tailored controller, is evaluated under typical therapy cycling conditions. The system's performance is demonstrated through metrological analysis and beam property comparisons. Most importantly, the results show the possibility of significant improvements in treatment time reduction. Ultimately, the already achievable beam position accuracy, and spill structure in the treatment rooms, enable the start of commissioning in 2025.
Paper: THPM001
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM001
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM002
VHEE FLASH radiotherapy: cutting-edge research at CLEAR, the CERN Linear Electron Accelerator for Research
2691
With the current availability of cost-effective and compact electron LINACs operating in the 100-200 MeV energy range, there has been a growing interest in using Very High Energy Electron (VHEE) radiotherapy (RT) for cancer treatment. A particularly intriguing aspect is the Ultra High Dose Rate (UHDR) or FLASH dose regime, which focuses on damaging cancerous cells while sparing healthy tissues. VHEE beams are well-suited for FLASH RT, given their deep penetration and high beam current, making them effective for treating large, deep-seated tumors. The CLEAR (CERN Linear Electron Accelerator for Research) facility has been at the forefront of exploring VHEE and FLASH RT, conducting numerous unique experiments in collaboration with multidisciplinary user groups having experience in dosimetric, chemical, and biological studies. This paper introduces recent measurements, techniques, and methods used to observe the FLASH effect at CLEAR.
Paper: THPM002
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM002
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM007
Time-varying Bayesian optimisation for continual optimal injection in the CERN PS Booster
2695
The Proton Synchrotron Booster (PSB) receives 160 MeV H- ions, which are converted to protons at injection via a charge exchange mechanism, an upgrade that allows the production of low-loss high-intensity beams (> 10^13 per ring). To mitigate losses due to space charge, horizontal phase-space painting is performed with a system of fours kickers whose pulse is customisable via time and amplitude parameters. Recent work has shown that classical optimisation algorithms can find the optimal parameter values on both a digital twin and the real machine. However, these techniques: do not handle system-state time variations, do not continually update the parameters during operation, require non-negligible dedicated beam time and are usually not robust to observation noise. We suggest time-varying Bayesian optimisation and show that it addresses each of the previous issues at low development and deployment cost. This work improves the operation of the PSB and contributes towards the goal of automating the operation of particle accelerators.
Paper: THPM007
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM007
About: Received: 19 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM008
Virtual temperature measurements of ferrite in in-vacuum kicker magnets
2699
The Large Hadron Collider (LHC) Injector Upgrade project has achieved unprecedented beam brightness levels, to fulfill the High Luminosity LHC requirements. This higher intensity has introduced significant challenges for some of the Super Proton Synchrotron (SPS) kickers, specifically concerning beam-induced heating and vacuum rise due to electron cloud. The primary concern is the integrity of the ferrite within the kicker magnets, which is critical to the system's operation and availability. Currently, temperature monitoring relies on temperature probes (PT100) installed on the magnet's frame, but these do not provide direct measurements of ferrite temperature. To address this limitation, we present a method using deep learning techniques to develop a virtual temperature sensor, enabling real-time monitoring of ferrite temperatures across the kicker module. We apply this approach to some of the SPS injection kicker family, the so-called MKP-S, and discuss the general applicability of the method to other systems.
Paper: THPM008
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM008
About: Received: 20 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM009
Model-based optimisation for automated multi-turn extraction tuning at the CERN Proton Synchrotron
2703
Multi-Turn Extraction (MTE) is a resonance-based technique employed in the CERN Proton Synchrotron (PS) to split the beam in horizontal phase space before extraction to the Super Proton Synchrotron (SPS). The splitting efficiency is evaluated based on the uniformity of intensities across the beamlets, requiring fine-tuning of multiple parameters. In this paper, we investigate the influence of key parameters on MTE efficiency to improve the understanding of their impact on the process. Using a Gaussian Process model and various visualization techniques, we assess the sensitivity of the MTE efficiency to horizontal tune, transverse feedback gain, excitation frequency, beam intensity and magnetic hysteresis. Results from experiments and simulations indicate a complex, non-convex relationship between MTE performance and the parameters listed above. Additionally, external factors such as thermal fluctuations may contribute to performance variability. Our findings highlight the need for a model-based controller to counteract parameter drift, thereby ensuring consistent MTE beam quality during operation. We propose a solution supported by experimental results.
Paper: THPM009
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM009
About: Received: 26 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
THPM010
Using machine learning techniques for BGI-based profile measurements at the CERN PS
2707
The Beam Gas Ionization (BGI) instrument provides a non-destructive method for monitoring transverse beam profiles by detecting free electrons produced during beam-gas ionization. Utilizing a Timepix-family detector, the BGI setup at the CERN Proton Synchrotron (PS) includes two instruments dedicated to horizontal and vertical plane measurements. However, the quality of these measurements is often compromised by artifacts, such as beam losses, which degrade profile quality, make the analysis significantly more difficult and ultimately affect the instrument performance. To address these challenges, this contribution explores the application of machine learning techniques for effective background removal. Both supervised and unsupervised approaches are evaluated on data acquired from the operational systems to improve the accuracy and reliability of the reconstructed profiles. Furthermore, the computational performance and time complexity of these methods are evaluated to ensure that the proposed solutions are compatible with the operational requirements of the BGI system.
Paper: THPM010
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM010
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
Machine learning-based model predictive control of the FRIB SRF
A machine learning-based model predictive control (MPC) application has been developed for the RFQ control at Facility for Rare Isotope Beams (FRIB). In this work, we extend this approach to broader applications at FRIB, the superconducting radio frequency (SRF) control. A machine learning model is trained to learn the correlations between the beam loss and the SRF signals. With the model, a MPC contoller is implemented to minimize the beam loss with high efficiency.
THPM012
Optimizing collimator positions using bayesian optimization in the Fermilab MI-8 transfer line
2711
Collimators are used to minimize losses and to remove particles that would otherwise get lost downstream and irradiate the machine. Finding the optimal jaw positions is time consuming and with the upstream beam properties changing, the collimation settings would need to be readjusted each time. Therefore, a method to optimize collimator positions and to operate them at full capacity in a short time is required for loss control downstream. A study of collimator positions was conducted and a machine learning (ML) model was developed to predict optimal collimator positions. Bayesian Optimization (BO) was used to calculate new jaw positions from the ML model. The results of BO and usage of ML for better performance of the collimation system are presented in this paper.
Paper: THPM012
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM012
About: Received: 29 May 2025 — Revised: 01 Jun 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
Machine learning driven beam emittance optimization at EuXFEL
Planned upgrades of the European X-Ray Free Electron Laser (EuXFEL) target higher photon energy and a high duty-cycle operation up to CW operation, critically depending on improvements of the beam slice emittance of the electron gun. We are addressing this challenge by the application of deep learning techniques to create an inverse model that predicts optimal parameter configurations for the photoinjector, enabling targeted control and minimization of beam emittance. This methodology involves sampling synthetic training data through comprehensive beam dynamics simulations and introduces a machine learning-based strategy for prediction of optimal gun parameters as well as temporal pulse shaping, accommodating a family of pulse distributions including flattop and Gaussian shapes. We present results from trained neural networks with various architectures and outline our research on the invertibility of the forward model by connecting our approach to the theory of inverse problems.
First high-power RF tests of cavities for BESSY II with a new mTCA-based LLRF system
The 3rd-generation synchrotron light source BESSY II is undergoing a series of modernization measures to maintain its leadership role until BESSY III starts its operation, planned for in 2035. The modernization of the LLRF control systems is one of these measures in the so-called BESSY-II+ project. Prior to the deployment of the new mTCA-based digital systems to control the fundamental frequency cavities at the booster and storage ring, a test stand was set up provide the opportunity for extensive offline testing and debugging. The test stand is consists of a HOM-damped 500-MHz cavity, a 80-kW Solid State Amplifier (SSA), a mTCA crate and all the ancillary systems required for high-power RF cavity operation. In this paper we discuss the results of the high power tests in continuous-wave operation, as required for the BESSY II storage ring, and in ramped mode, as required for the BESSY II booster during beam injection.
Toward online learning of a cavity mechanical model for improved resonance control
The energy consumption of particle accelerators becomes an important issue nowadays. One option to address this is to employ cavities with a very high quality factor. Despite its energy saving potential, such quality factor poses a serious control problem, because the cavities become very sensitive to noise affecting their resonance frequency. A resonance controller is thus needed. There have been many attempts to design such a controller, using both model-based and model-free approaches. Yet the problem still remains an open issue. An important aspect that is apparently missing in existing solutions is a real-time adaptation to plant variations. Specifically, variations in the frequency of unwanted mechanical oscillations that perturb the cavity. In this contribution, we show the dependency of these oscillations on various operating conditions. By doing so, we motivate the adoption of a machine learning-based adaptive modeling which learns the cavity dynamics online. Such modeling is expected to improve the performance of the resonance controller by making it more robust to plant variations.
THPM016
Neural networks approach for controlling a waveform pattern of the paint bump power supply at J-PARC RCS
2715
Four horizontal paint bump magnets and two vertical paint bump magnets are used for the painting injection to produce a high intensity beam at J-PARC RCS. These paint bump power supplies are composed of the IGBT chopper units, and so the requirement waveforms can be controlled with high precision less than 1%. By using software that automatically creates input voltage (IV) patterns according to the characteristics of the power supply and direct manual adjustment of IV patterns, the current deviation of the painting pattern (PP) is less than ±0.2%.The adjustment of one PP needs about one hour and several days to adjust a total of 90 patterns with six paint bump magnets. Therefore, a reduction in adjustment time is required. In addition, to mitigate the beam loss caused by beam orbit control to a minimum level, we would like to realize a more precise current deviation. To adjust for these PP, we performed neural networks (NN) approach. By learning the IV patterns and output current patterns as training data, the highly accurate IV patterns were confirmed.The presentation reports on the preliminary training results using NN.
Paper: THPM016
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM016
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
THPM017
Uncertainty-Quantified Machine Model Construction Using Physics-Informed Gaussian Processes and Bayesian Optimization
2718
To construct a closed orbit model for an accelerator ring with intrinsic uncertainty quantification from orbit measurements, a physics-informed Gaussian Process model is proposed based on a stochastic ensemble of MAD-X lattices. Key advantages compared to LOCO (Linear Optics from Closed Orbits) include (1.) uncertainty-enabled orbit prediction in between BPMs (beam position monitors), (2.) fitting of a parameter distribution (dipole-like field errors) which inherently models uncertainty, (3.) incorporation of measurement uncertainty from BPM noise, and (4.) an active learning approach which can be more sample efficient than measuring an orbit response matrix. A case study is presented for the GSI heavy ion synchrotron SIS18 with various simulated applications, in particular constructing an effective machine model with minimal orbit uncertainty around the ring, and orbit correction to achieve minimal deviation at a specific location such as, e.g., the septum to control beam loss during slow extraction. This physics-inspired Gaussian Process regression approach shows potential to be applied to optics correction and further applications beyond closed orbit correction.
Paper: THPM017
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM017
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM018
Efficient accelerator operation with artificial intelligence based optimization methods
2722
Tuning injectors is a challenging task for the operation of accelerator facilities and synchrotron light sources, particularly during the commissioning phase. Efficient tuning of the transfer line is essential for ensuring optimal beam transport and injection efficiency. This process is further complicated by challenges such as beam misalignment in quadrupole magnets, which can degrade beam quality and disrupt operations. Traditional tuning methods are often time-consuming and insufficient for addressing the complexities of high-dimensional parameter spaces. In this work, we explore the use of advanced AI methods, including Bayesian optimization, to automate and improve the tuning process. Initial results, demonstrated on the transfer line of KARA (Karlsruhe Research Accelerator) at KIT (Karlsruhe Institute of Technology), show promising improvements in beam alignment and transport efficiency, representing first steps toward more efficient and reliable accelerator operation. This study is part of the RF2.0 project, funded by the Horizon Europe program of the European Commission, which focuses on advancing energy-efficient solutions for particle accelerators.
Paper: THPM018
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM018
About: Received: 28 May 2025 — Revised: 29 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
Machine learning-driven phase space reconstruction for heavy ion linac beams
This study explores the application of machine learning techniques for phase space reconstruction of heavy ion linac beams, a critical aspect of understanding and optimizing beam dynamics for advanced nuclear physics experiments. Modern machine learning methods, including neural networks and differentiable simulations, are employed to reconstruct the multidimensional phase space distribution from limited and noisy measurement data. These methods excel at modeling nonlinear relationships and inferring missing information, addressing traditional challenges in high-dimensional data processing. The framework uses beam diagnostics data, such as beam profiles and time-of-flight measurements, to train predictive models capable of accurately reconstructing spatial, angular, and energy distributions. Preliminary results demonstrate significant improvements in reconstruction accuracy compared to conventional approaches, with potential for real-time implementation. This work underscores the effectiveness of machine learning for beam diagnostics and optimization, offering a pathway to enhanced performance and efficiency in heavy ion linac operations.
A Bayesian multi-objective framework for optimizing an electron injector linac
This study introduces a multi-objective Bayesian optimization framework to enhance the performance of electron linear accelerators in Fourth Generation Synchrotron Radiation facilities. By focusing on minimizing horizontal and vertical emittances and energy spread at the linac exit, the approach targets improved beam quality essential for advanced synchrotron applications. Traditional methods face challenges balancing these competing objectives due to system complexity and nonlinearity. Bayesian optimization addresses this by combining probabilistic modeling and sequential sampling to efficiently navigate the high-dimensional parameter space, balancing exploration and exploitation while iteratively refining predictions. Results demonstrate the framework's ability to reduce emittances and energy spread effectively and efficiently. This scalable, adaptive method offers a robust optimization strategy for improving performance across accelerator systems in multi-objectives
Enhancing ALS injector performance through data analysis
This study presents a data-driven methodology aimed at enhancing the performance and reliability of the injector at ALS. We show a data acquisition system for capturing and analyzing the parameters affecting the injection process to find patterns and improve reliability. We analyze the recorded injection parameters to find key correlations and patterns within the multidimensional parameter space, gaining insights into injector dynamics and potential areas for optimizing the injection process. Furthermore, we present first steps towards a parametric digital twin of the ALS injector based on the recorded data to enable more precise predictions of injector behavior, facilitate rapid troubleshooting, and support the development of advanced control strategies.
THPM022
Augmented Reality for Accelerator Operations: A Virtual Control Room Proof of Concept
2726
Particle accelerator control rooms rely on fixed workstations with multiple monitors and on-site personnel, limiting operational flexibility. When experts connect remotely—whether for troubleshooting, monitoring, or collaboration—current setups often lack sufficient screen space, forcing users to toggle between interfaces and reducing situational awareness. Recent advancements in augmented reality headsets enable spatially aware virtual control rooms, allowing users to arrange and interact with multiple control panels in 3D space, improving efficiency and collaboration. In this work, we present our vision for a Virtual Control Room, addressing key user experience challenges, outlining the technical infrastructure, and demonstrating first prototype results from the Advanced Light Source.
Paper: THPM022
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM022
About: Received: 04 Jun 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM023
The journey towards a specialized text embedding model for accelerator physics
2730
We present PhysBERT and AccPhysBERT, specialized sentence-embedding models trained on 1.2 million arXiv physics papers and fine-tuned for accelerator physics, respectively. Evaluation across retrieval, clustering, and similarity tasks shows gains of up to 12\% over general-purpose models for physics corpora and 18\% for accelerator-specific tasks. Applications include semantic reviewer–paper matching, Retrieval-Augmented Generation for control-room logbooks, and rapid sub-domain adaptation. We analyze key design choices—data curation, masking objectives, and contrastive fine-tuning—and outline strategies for continual adaptation, providing a blueprint for domain-specific embeddings in the physical sciences.
Paper: THPM023
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM023
About: Received: 30 May 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM024
Machine learning-driven longitudinal phase space reconstruction for enhanced beam tuning at LANSCE
2733
The Los Alamos Neutron Science Center (LANSCE) relies on accurate tuning of its Drift Tube Linacs (DTLs) to maintain beam quality and operational efficiency. This work introduces a novel machine-learning-based approach to reconstruct the longitudinal phase space (LPS) at the entrance of DTL Tank 1 using two-dimensional phase scans from Tanks 1 and 2. A Deep Neural Network trained on synthetic datasets generated by GPU-accelerated simulations integrates real-time diagnostic data to infer high-resolution LPS distributions. By solving this inverse problem efficiently, the method improves beam delivery precision while reducing operator intervention. Early results indicate that this approach can enhance LANSCE’s operational capabilities, providing a robust framework for accelerator tuning and diagnostics.
Paper: THPM024
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM024
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM025
Insertion device correction based on machine learning models at the MAX IV 3 GeV ring
2737
Insertion Devices (ID) in particle accelerators introduce orbit distortions that must be compensated. At MAX IV, this compensation traditionally relies on feed-forward tables which are time-consuming to measure, and sensitive to changes in accelerator settings. This study explores the use of machine learning (ML) to automate the generation of feed-forward tables without requiring extensive measurements. Using archived data from ID gaps, beam position monitors (BPM), and corrector magnets, a neural network-based model was developed to replicate the current ID compensation system. Preliminary results show that the model effectively reproduces the existing compensation behavior and suggests potential for adaptive feed-forward tables that refine themselves with online data. In parallel, alternative ML approaches focused on minimizing beam position errors are being investigated. These efforts aim to improve the maintainability of ID compensation and prepare orbit control for future optical changes and new operational scenarios.
Paper: THPM025
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM025
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 30 May 2025 — Issue date: 10 Jul 2025
THPM026
Application of Bayesian optimization for the TLS booster extraction
2740
Bayesian optimization is a method for performing global optimization on black-box functions using Gaussian processes and an acquisition function. In accelerator parameter tuning, when the number of adjustable parameters is large, finding the global optimal parameters can be time-consuming and often relies on the operator’s experience. Bayesian optimization is well-suited for such scenarios. In this report, we take the booster extraction of the Taiwan Light Source (TLS) as an example, selecting six key adjustable parameters to optimize the extraction efficiency from the booster ring to the transport line. The preliminary test results and implementation details will be discussed in this paper.
Paper: THPM026
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM026
About: Received: 08 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM030
Characterization of four-dimensional phase space for space charge-dominated beams using novel beam diagnostic techniques and generative phase space reconstruction at the KOMAC beam test stand
2743
Transverse phase space (x, x’, y, y’) measurement is crucial in beam physics to optimize the beam parameters. Typically, the phase space information of space charge-dominated beams can be characterized using well-established methods such as pepper-pot and movable slit-based scans. In addition, recent studies show that calibration of transfer matrix with considering space charge forces provides quantitative agreement in a solenoid scan-based emittance measurement. In this study, we characterize the space charge-dominated, 1 MeV/n proton beam at the Beam Test Stand (BTS) of Korea Multipurpose Accelerator Complex (KOMAC) using various beam diagnostic instruments such as pepper-pot, virtual pepper-pot, and multi slits. Furthermore, we investigate the usage of generative phase space reconstruction, based on neural networks and differentiable simulations, in the context of space-charge calibrated matrix computations and self-consistent beam propagation. We also discuss the comparison of the phase spaces obtained by conventional diagnostics, confirming the effectiveness of the reconstruction algorithm and advanced diagnostic methods for analyzing space charge-dominated beams.
Paper: THPM030
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM030
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM031
Beam Energy Forecasting using Machine Learning at the CLEAR accelerator
2747
In particle accelerators, accurate and stable beam parameters are crucial for experimental success. Traditional methods for measuring parameters like beam energy often rely on invasive techniques that disrupt experiments. This paper presents a novel, non-invasive machine learning-based approach to predict beam energy using parasitic measurements, enabling real-time estimation without interference. The method employs a predictive model optimized for one-step-ahead forecasting and uses time-series data decomposition to handle complex beam energy dynamics. Recursive prediction strategies allow the model to anticipate future variations autonomously. Preliminary results from experiments at the CLEAR accelerator demonstrate the model’s ability to capture both slow trends and rapid energy shifts, adapting to diverse experimental needs. These findings showcase the potential of machine learning to measure beam energy, offering a real-time, non-destructive alternative to conventional methods. This approach promises significant advancements in accelerator-based applications, especially where destructive techniques are impractical.
Paper: THPM031
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM031
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 06 Jun 2025 — Issue date: 10 Jul 2025
THPM032
Toward autonomous control: reinforcement learning for improving CLEAR accelerator performance
2751
Particle accelerators like CLEAR (CERN Linear Accearator for research) are essential tools in advancing various scientific fields. Automating their operation to ensure stability and reproducibility is crucial for future large-scale projects. This paper explores the first steps toward autonomous control of the CLEAR beamline, focusing initially on beam steering and advancing to complex tasks like quadrupole alignment, vital for operational stability. Reinforcement Learning (RL) agents that adapt in real-time via beam screens measurements were trained and tested. The approach is optimized for sampling efficiency, addressing the high cost and invasiveness of data collection in accelerator environments. The method enables single-shot optimization for real operations, reducing the need for manual intervention. Results show that a few hours of training suffice for effective single-step corrections in the latter part of the CLEAR beamline, inspiring further development by the CLEAR research team.
Paper: THPM032
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM032
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
Beam orbit tuning via reinforcement learning at FELiChEM
The online optimization and debugging of particle accelerator devices have always been a challenging task. Traditional manual debugging is time-consuming and labor-intensive, and there is a phenomenon of slow drift in the machine's operating state after debugging, requiring experts to repeatedly debug. With the improvement of computing power, machine learning has developed rapidly in recent years, making it possible to train more complex models. Deep reinforcement learning models, as intelligent agents, have the ability to interact with the actual environment and learn the best strategies. By interacting with the FEL environment through deep reinforcement learning models, automatic debugging of FEL can be achieved
THPM034
MTE measurements at the ASU cryogenically cooled DC electron gun
2755
The ASU cryogenically cooled DC electron gun represents a state-of-the-art platform for testing novel photocathodes at room and cryogenic temperatures. The key electron beam diagnostic tool of this setup is the four-dimensional (4D) phase space reconstruction using the pinhole scan technique. In this work, we use the 4D phase space measurement to extract the Mean Transverse Energy (MTE) obtained from cathodes in this gun. We also establish the limits and accuracy of the 4D phase space and emission area measurements and estimate their effects on the MTE extracted. The results, validated through simulations and complementary measurements establish the use of the 4D phase space measurement technique to obtain the MTE. Using this approach, we measure the MTE from alkali antimonide photocathodes at varying temperature and electric field conditions. This study provides a robust foundation for future experiments with the ASU electron gun and beamline, paving the way for advanced photocathode characterization under cryogenic conditions.
Paper: THPM034
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM034
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
THPM035
MENT algorithm for transverse phase space reconstruction at SIRIUS
2758
The injector system of SIRIUS, the brazilian 4th generation synchrotron light source, currently operates with non-ideal injection efficiencies, which may impose limits to future top-up operation modes. Within this context, diagnostic techniques to access beam quality in the injector are essential tools for optimizations. In this work, the MENT algorithm was implemented for the reconstruction of two-dimensional probability densities, aiming to determine the electron density in the transverse phase space at the end of the LINAC. The implemented method has been validated through simulations of several distributions, demonstrating its reliability, and applied to analyze preliminary experimental results.
Paper: THPM035
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM035
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM037
Longitudinal beam size measurement at the Novosibirsk FEL
2762
The Novosibirsk Free Electron Laser (NovoFEL) is a facility that consists of three free electron laser (FEL) systems installed on different parts of the Energy Recovery Linac (ERL). These three FELs share the same acceleration system, which enables the generation of high average electron current, typically around 10 mA. Precise measurement of the electron beam parameters is essential for monitoring the performance of the accelerator and tuning its operating modes. One of the most important parameters is the length of the electron bunch, as it directly affects the efficiency of the laser radiation generation process. This paper presents the results of experiments conducted to study the behavior of the longitudinal beam size in various Novosibirsk FEL lasers. For these experiments, we used Cherenkov radiation produced by a beam of electrons passing through a thin aerogel plate. The resulting flash of radiation was captured by a streak camera, allowing us to determine the longitudinal size of the electron beam. The results of the study on the dependence of the longitudinal beam size on various accelerator parameters are presented.
Paper: THPM037
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM037
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
THPM038
Measurement of the radiation damping time via optical methods
2766
The radiation damping time is a crucial parameter that depends on the overall magnetic structure of the accelerator. Accurate measurement of this damping time can provide insights into the fidelity of the accelerator model by allowing for a comparison with calculated damping time values. In this study, we present a series of measurements of radiation damping times at the VEPP-4M and VEPP-2000 collider at BINP. In order to determine the damping time, we recorded the transverse beam profile using a digital camera. The results includes study of the damping times at revolution frequencies and different energies of the beams.
Paper: THPM038
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM038
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM039
Fast cyclotron beam probe at UC Davis Crocker Nuclear Laboratory
2770
The UC Davis Crocker Nuclear Laboratory houses a 72-inch multi-species Isochronous Cyclotron built in the 1960’s. For many years, previously unexplained beam dynamics have been indirectly observed at the cyclotron by both internal and external experimenters. Investigating these effects within the cyclotron, at the bunch level, has proven particularly challenging due to the cyclotron's harsh environment of strong magnetic fields, high radiation levels, intense RF interference, and limited space. To address these challenges, a compact segmented beam probe was developed, utilizing a scintillator array target coupled to a SiPM array positioned outside the cyclotron via fiber optic cables. This novel beam probe has enabled precise, high-speed measurements of individual beam bunches, providing data to theoretical models and deepening the understanding of beam dynamics allowing for more precise operation of the cyclotron. These advancements are driving efforts to optimize cyclotron performance for diverse applications, including isotope production, ocular melanoma therapy, and a variety of experimental research.
Paper: THPM039
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM039
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
Data-Driven Modeling for the Magnetic Field Prediction in Particle-Accelerator Magnets Based on Measured Electrical Parameters
The precise modelling of magnetic fields in particle accelerator magnets is essential for optimizing their performance and ensuring the accurate control of particle beams. Traditional modelling approaches require extensive multi-physics simulations and electrical and magnetic measurements. In this study, we explore using data-driven artificial intelligence models to predict the magnetic field based on the magnet's voltage and excitation current. We conducted a case study to validate this approach using dipole and quadrupole magnets from the Super Proton Synchrotron (SPS) at CERN. The results demonstrate that AI-based models can achieve accuracy comparable to traditional measurement methods. Additionally, the flexibility of AI models allows for continuous learning as new data becomes available, further enhancing the dynamic control capabilities of particle accelerators. Future work will focus on refining the models, expanding their applicability to different types of magnets, and exploring their integration into accelerator control systems for real-time field adjustments and optimization.
THPM042
Online analysis of proton and lead ion LHC schottky spectra
2773
The Schottky signals encode various beam and machine parameters, such as betatron tune, chromaticity, momentum deviation and transverse emittance. In this contribution we present the architecture and the performance of the system estimating these parameters in real-time, providing the only non-invasive measurement of chromaticity at the Large Hadron Collider. The obtained results are assessed based on chromaticity drift predictions and the measurements from the independent instruments. The remaining challenges are discussed with the outlook for further development given.
Paper: THPM042
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM042
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM043
Performance assessment of profile monitors at CERN’s LHC using systematic analysis tools
2777
In this paper, we investigate statistical and systematic tools to establish performance benchmarks for future beam profile measurement tools, using extensive data from both prototype and legacy Beam Wire Scanners and the Beam Synchrotron Radiation Telescope at the LHC. We detail direct and comparative analyses, including variability in beam size measurements, positioning accuracy, and profile shape fidelity relative to theoretical models, with particular focus on non-Gaussian tails influenced by the beam halo effect. This work establishes a foundation for systematic performance assessment applicable to both current and next-generation profile measurement tools.
Paper: THPM043
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM043
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM044
Selecting 1D projections for 2D tomography reconstruction
2781
Previous works on reconstructing the 4D phase space using tomography require optimal selection of projection views to achieve accurate reconstruction. In 2D reconstruction, the process is straightforward, as an object can be evenly sampled by dividing the angles evenly. However, extending this concept from 2D to 4D is not intuitive. This work demonstrates that quaternions can be used to more effectively describe views in 4D and introduces the Fibonacci Flower algorithm and repulsive force algorithm to evenly space views in 4D space in order to achieve higher reconstruction accuracy.
Paper: THPM044
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM044
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM046
Stand-alone operation of the dual-core cryogenic current comparator for FAIR
2785
The Cryogenic Current Comparator (CCC) is a superconducting device for measurement of low intensity beams with magnetic fields in the range of fT. It uses a Superconducting Quantum Interference Device (SQUID) as an ultrasensitive magnetometer and an elaborated superconducting shield for its protection from external magnetic fields. The system is operated in a helium bath cryostat, which has to fulfill many requirements, such as being non-magnetic, pressure/temperature stable (mK), vibration dampening, UHV fit, bakable, compact and accessible for maintenance and repair. First operation of a CCC as beam current monitor was achieved in the 90s at GSI. The idea has been updated for measurement of slow extracted beams and exotic ions at FAIR, and since 2014 there has been steady optimization by an international collaboration of expert institutes. Looking at noise figures and current resolution as well as practical applicability and costs, a Dual-Core CCC (DCCC) has turned out as best candidate for FAIR. In parallel to detector development the cryostat has been investigated and improved. It has recently achieved stand-alone operation, which is a main requirement for FAIR.
Paper: THPM046
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM046
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM047
Direct diode detection tune measurement in the BESSY II booster
2789
The Direct Diode Detection (3D) method for transverse tune measurement, which was developed at CERN, has been implemented in numerous hadron machines and has recently been tested in electron machines. This method can provide orders of magnitude greater sensitivity to betatron oscillations than conventional beam position measurement approaches, which is particularly useful in fast-ramping synchrotrons such as the Booster of the BESSY~II light source. Typical systems used for tune measurement in an electron storage ring, which rely on the beam being in a relatively steady state, are not well-suited for fast-ramping machines; in order to measure the tune throughout the full acceleration ramp using conventional beam position approaches in the BESSY~II Booster, it is necessary to use large external excitation which disturbs injection into the storage ring. Here we describe tune measurement in the BESSY~II Booster using diode detectors, which allows for tune measurements during the full acceleration ramp with little to no external excitation and therefore no disturbance to user operation.
Paper: THPM047
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM047
About: Received: 02 Jun 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM048
KEK ATF linac, damping ring accelerating field and RF-gun laser system phase&litude stability study
2793
KEK Accelerator Test Facility (ATF) conducts beam instrumentation R&D for International Linear Collider (ILC) project. ATF includes 1.3 GeV normal conductivity S-band Linac and Damping Ring (DR). There are 9 S-band pulsed klystrons at Linac, which supply High-Power RF to accelerate electron beam up to 1.3 GeV, 1 CW klystron at DR. The electron beam is generated by a photocathode irradiation by a laser pulse. The laser pulse generation is synchronized with the accelerating fields by the laser system oscillator Piezo feedback. These Linac, DR High-Power RF field and laser pulse arrival time jitter and/or drift define the stability of the electron beam parameters, such as average energy, energy spread (RMS), emittance, bunch charge etc. This study demonstrates KEK ATF Linac and DR High-Power RF field phase and amplitude, as well as the laser system oscillator laser pulse arrival stability measurement results. Also, FPGA board based digital Low-Level RF phase&litude feedback system is described in this report.
Paper: THPM048
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM048
About: Received: 04 Jun 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM049
FPGA board based cost-effective, robust and flexible online waveform monitors development, test and implementation at KEK Accelerator Test Facility
2797
KEK ATF is the Accelerator Test Facility devoted to develop an advanced beam instrumentation technologies for ILC (International Linear Collider) project. There are seven main subsystems at the facility: RF-Gun laser, Linac, Beam Transport (BT), Damping Ring (DR), Extraction Line (EXT), Final Focus (FF) and Interaction Point Beam Size Monitor (IP BSM). In order to monitor laser pulse output power, bunch charge transmission between accelerator sections and background at Final Focus, the online waveform monitors based on the RedPitaya STEMlab 125-14 and SIGNALlab 250-12 FPGA boards were programmed, tested implemented at KEK ATF. This study demonstrates results of the bunch charge transmission, laser pulse output power and background level monitoring using the FPGA board based waveform digitizers. Also, the FPGA boards System-on-Chip programming and control software implementation details, as well as a pulse shaping technique, will be explained in this report.
Paper: THPM049
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM049
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
THPM050
Study of laser-beam arrival time synchronization towards sub-picosecond stability level
2800
In order to achieve laser pulse to electron beam arrival time sub-picosecond stability at the accelerator facilities, a new Low-Level Radio-Frequency system clock generators synchronization architecture is currently under investigation in collaboration between KEK (Japan) and IJClab (France). The system is based on the 10 MHz frequency generator (Stanford Research System), White Rabbit Switch, SkyWorks Si5362 clock generator and IDROGEN boards. This report demonstrates the measurement results of the long-term and short- term synchronization between clock generators. Also, the architecture details are discussed in this report.
Paper: THPM050
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM050
About: Received: 27 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
Prediction of electron beam parameters through diffraction images
Achieving precise and real-time diagnostics of electron beam characteristics is critical for enhancing the performance of ultrafast electron diffraction (UED) and electron microscopy (UEM) techniques. Key parameters such as bunch size, emittance, energy spread, and spatial pointing jitter directly influence the quality and accuracy of experimental results. Traditional diagnostic methods often lack the ability to provide continuous, real-time, and non-intrusive monitoring, limiting their effectiveness. This work presents a machine learning (ML)-based approach that utilizes a small dataset of known beam parameters in combination with real-time diffraction image data recorded during experiments to predict electron beam characteristics for each run. This approach enables continuous optimization of beam stability without interfering with the experiment and facilitates real-time updates to UED parameters during data collection. As a result, it significantly improves the precision, reliability, and overall performance of UED and UEM experiments.
High accuracy measurement of the absolute energy of the MAinz MIcrotron by undulator radiation interferometry
The Mainz Microtron is an electron accelerator, which delivers electron energies up to 1.6 GeV, with a small spread of the energy σ_beam < 13 keV. Besides a small energy spread, the high quality of the beam allows producing high coherent synchrotron radiation. The light from two spatially separated and movable light sources (undulators), can be superimposed to render an interference pattern. The ideal applications are high accuracy absolute energy measurements of the relativistic electrons. Experiments at this beam line have yet been carried out at 180 MeV, 195 MeV and 210 MeV. The radiation lies in the optical range where also Fresnel Diffraction patterns occur, which features allow very precise alignment control.
Orthogonal dual-slit emitttancemeter for the C-band photocathode RF-gun
To enhance the performance of next-generation X-ray Free Electron Lasers (XFELs), it is crucial to produce high-quality electron beams with low emittance, particularly for attaining emittances below 0.2 mm.mrad for 100 pC bunch charges. This study introduces an emittance measurement method using an orthogonal dual-slit technique, aimed at enhancing measurement efficiency and achieving the necessary measurement accuracy for such small emittances. An emittance meter based on this method has been designed for a C-band photocathode RF gun at the CSNS campus. Finally, we present numerical simulations to optimize the primary parameters of the emittance meter, focusing on beam drift distance, combined with the motion accuracy of the stepper motor and the expected resolution of the optical observation system to ensure the accuracy of the emittance measurement.
Design considerations of the bunch-by-bunch transverse feedback system for the CSNS RCS
The CSNS RCS (Rapid Cycling Synchrotron) is a proton accelerator designed to achieve a target beam energy of 1.6 GeV, with a typical operating intensity of 140 kW, which is expected to increase to 500 kW after the CSNS II upgrade. However, a significant current instability has been observed during the 100 kW beam operation. To mitigate this instability, techniques such as operational tuning and chrominance modulation were previously used to make the 100-kilowatt beam operate stably. In order to face the subsequent stronger instability, a bunch-by-bunch transverse feedback system is developed to mitigate the coherent lateral oscillations caused by instability and injection errors. The system consists of a beam position monitor, strip-line kicker, power amplifier, and signal processing electronics.
Preliminary commissioning results of the LW prototype at CSNS
China Spallation Neutron Source (CSNS) accelerator complex will employ a new superconducting accelerating section to provide high beam power. To prevent contamination of the superconducting cavity surface caused by sputtering, shedding, or melting of medium materials during interceptive beam measurements, the second phase of the China Spallation Neutron Source (CSNS) superconducting linac section will adopt laser stripping technology for transverse distribution measurements of the negative hydrogen beam at nine stations. This paper describes the design of LW prototype including laser parameters, optics transmission and simulation of laser-beam interaction. And the preliminary results of the profile measurement where beam energy is 80MeV are also presented.
Test of the large-diameter CNT wire for the high-intensity beam diagnostics
In particle accelerator complex, measurement of the beam profile monitor is important to mitigate the beam loss in a high-intensity beam linac. However, traditional metallic wires in wire scanner monitor (WSM) face thermal challenges with high energy deposition leads to rapid break. Since the CNT wire has a high-temperature tolerance and a small energy deposit due to the low density compared with the tungsten wire, it is selected as strong wire to measure high intensity beam. With the development of carbon nano technology, a new production process for wire scanner is introduced. Besides, this paper examines the thermal durability of carbon nanotubes (CNT), carbon fiber. And the details of the study of CNT wire scanner monitor at CSNS are also presented.
THPM057
A full digital beam position and phase measurement signal processing algorithm based on FPGA designed for linear accelerator
2804
A new digital beam position and phase measurement (BPM) system was designed for the ion-Linac (iLinac) accelerator in the High Intensity heavy ion Accelerator Facility (HIAF). The fundamental and the second harmonic signals are retrieved from the BPM electrodes to simultaneously calculate their respective beam positions and phases. All data acquisition and digital signal processing algorithm routines are performed in a field programmable gate array (FPGA). The position and phase information are obtained by using the in-phase and quadrature (IQ) demodulation method. A practical and straightforward method is used to generate the second harmonic reference signal for processing the second harmonics beam signal. The reconfigurable filters are integrated into the FPGA to allow the measurement of short beam pulse length. The laboratory test results show the achieved phase resolution is better than 0.2$^{\circ}$ and 0.03$^{\circ}$ when the input signal is -60 dBm and -45 dBm respectively. A position resolution better than 30 $\mu$m was achieved for an input power level of approximately -60 dBm, and it can reach 7 $\mu$m with the input power higher than -45 dBm. The entire execution time of the algorithm is accomplished within 3.4 $\mu$s, which provides a sufficient reaction time for the fast beam interlock signal to the machine protection system (MPS). The performance of this newly designed prototype BPM electronics was evaluated with the online proton beam.
Paper: THPM057
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM057
About: Received: 29 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
A non-destructive weak beam current measurement electronics for HIRFL
Non-destructive measurement of low-intensity charged particle beams poses significant challenges in beam diagnostics. At the Heavy Ion Accelerator Facility in Lanzhou (HIRFL), beams with currents below 1 μA are frequently used in experiments, which fall below the detection threshold of standard beam current transformers. To address this, a low-intensity monitoring system was developed, utilizing a sensitive capacitive pick-up (PU) and low-noise electronics. This system measures beam currents by digitally analyzing PU signal amplitudes using a homodyne detection scheme. Laboratory tests showed an amplitude nonlinearity of <0.5% within the operational range of 1 nA–45 μA and an amplitude resolution of 0.94 nA. Currently, four such systems are installed at HIRFL for monitoring low beam currents below 1 μA. Following absolute calibration with a Faraday cup, the system achieves accurate beam intensity measurements with a resolution of approximately 1 nA.
THPM059
Development of a DAQ system for a High Resolution cavity BPM for the future linear collider
2807
A cavity beam position monitor (cBPM) developed by CEA Saclay was installed at the end of the Accelerator Test Facility (ATF) linac to evaluate the combined performance of the monitor and its associated signal processing system. The setup incorporates a down-conversion architecture inspired by Royal Holloway, University of London (RHUL), and employs a digital down-conversion (DDC) algorithm to extract beam position. This configuration enables highsensitivity measurements of the transverse beam position. Preliminary results confirm successful signal acquisition and a clear position-dependent response, validating the integrated performance of the cBPM, analogue electronics, and digital processing chain. The results underscore the necessity of reliable local oscillator (LO) phase-locking to ensure precise position determination.
Paper: THPM059
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM059
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM060
Investigation of the leakage beam from the RF chopper using the BSM
2811
The Japan Proton Accelerator Complex (J-PARC) linac is operated with a peak current of 50 mA to deliver the 1-MW beam to the neutron target through the rapid cycling synchrotron (RCS). One of the source of the beam loss to limit the beam power is a leakage beam from an radio-frequency (RF) beam chopper at the frontend of the linac. Since the leakage beam is presented in the unintended RF bucket, it becomes the beam loss the during the acceleration in the RCS. Recently, the bunch-shape monitor (BSM) dedicated for the low-energy beam has been developed to measure longitudinal profiles after an radio-frequency quadrupole linac (RFQ)*. It is useful to investigate the leakage beam because the BSM is located at just after the chopper. Asymmetric longitudinal profiles were observed with the BSM, but the sensitivity should be improved to observe the leakage beam. Measuring the induced current from the target probe by using the BSM in the same way as the wire-scanner monitor, the leakage beam was observed in the horizontal profile measurement. Latest results are presented with discussing the classification of the leakage beam with respect to its time scale and source.
Paper: THPM060
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM060
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM061
Cavity beam position monitor signal matching by injection pulse
2814
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).
Paper: THPM061
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM061
About: Received: 30 May 2025 — Revised: 06 Jun 2025 — Accepted: 06 Jun 2025 — Issue date: 10 Jul 2025
THPM063
Extended phase space tomography for EOSD simulation considering crystal geometry effects
2818
This theoretical study presents an advanced method for longitudinal phase space tomography in electron storage rings, focusing on reconstructing phase space densities from electro-optical spectral decoding (EOSD) measurements that incorporate crystal geometry effects. The EOSD crystal geometry significantly impacts the measurement signal due to signal integration along its length and interference from wake fields and Cherenkov diffraction radiation (ChDR). These effects add challenges to reconstructing the original phase space density from experimental data. To address these challenges, we integrate two theoretical frameworks. First, we employ the Vlasov-Fokker-Planck equation to model the turn-by-turn evolution of the charge density distribution. Second, CST simulations of the bunch profile characterize the electric field inside the crystal, enabling a tailored simulation for the EOSD system at the Karlsruhe Research Accelerator (KARA). By combining these approaches, we propose a refined tomography method that more accurately reconstructs the longitudinal phase space from sensor data, effectively capturing the interplay between bunch dynamics and the EOSD system configuration.
Paper: THPM063
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM063
About: Received: 23 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM064
Terahertz streaking detection for longitudinal bunch diagnostics at FLUTE
2822
The Karlsruhe Institute of Technology is currently exploring a compact method of longitudinal electron bunch diagnostics with femtosecond resolution that has recently been demonstrated for other parameter ranges. The experimental setup utilizes a THz-based streaking approach with resonator structures, achieving both high compactness and efficiency. In this paper, we report on the experimental observation of streaking signals with our Compact Transverse Deflecting System, which has been successfully tested using two different resonators, an Inverse Split-Ring Resonator and a Tilted-Slit-Resonator.
Paper: THPM064
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM064
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
Measurement of slice energy spread of a high brightness electron beam using a passive dielectric-lined waveguide structure
In this study, we investigated the possibility of using a passive dielectric-lined waveguide structure on slice energy spread measurement of femtosecond electron beam. Such diagnostic setup for a 25 MeV electron beam with a duration of a few hundred femtoseconds is simulated using IMPACT-T. The DLW acts as a passive streaker by generating traverse wakefields that deflect the electron bunch. Simultaneously, a dipole magnet serves as a spectrometer, separating the slice energy distribution, which is then visualized on YAG screen. The DLW’s wakefields significantly broaden the transverse beam profile on the screen, with the beam tail experiencing a stronger transverse kick than the head. This effect results in a beam separation on the vertical axis. To analyze the wakefields, CST simulations are used to compute wake potential excited by a Guassian beam. By proper deconvolution, the corresponding transverse wake function is obtained. This wake function is combined with IMPACT-T simulations and a 6D phase space distribution to deduce the slice energy spread. The results demonstrate a promising approach for diagnostics that helps to optimize free-electron laser (FEL) drive beams.
THPM068
Recent diagnostic upgrades at the Solaris storage ring
2826
This work summarizes the most significant diagnostic upgrades that have been implemented, as well as those currently under development, at the Solaris synchrotron facility. These include the installation, startup, and initial testing of a Bunch-by-Bunch Feedback (BBF) system that is currently being implemented at the Solaris synchrotron. Once operational, the BBF system will provide real-time corrections on a per-bunch basis, significantly enhancing beam stability. Efforts are also underway to develop a system for measuring the vertical and horizontal tunes without disturbing the electron beam. Additionally, a beam loss monitoring system is being developed and installed. Complementing these activities, numerous diagnostic scripts have been created, including those that utilize fast acquisition and turn-by-turn data from beam position monitors.
Paper: THPM068
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM068
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
THPM069
Applications of waveform digitizers at the TPS and TLS control systems
2829
The retrieved waveform data include pulse magnet power supply waveforms, fast current transformer waveforms, wall current monitor waveform, RF power waveforms, beam signals, and more. These waveforms are crucial for diagnosing subsystem abnormalities and for long-term observation during routine beam operations. Various types of digitizers, capable of remotely accessing waveforms, have been deployed in the TPS and TLS control systems. To enhance data acquisition capabilities and stability, the waveform digitizers have replaced outdated oscilloscopes that were damaged due to prolonged use. Each type of waveform digitizer is equipped with specific sampling rates and data lengths based on the signal properties and intended applications. High-sampling-rate (10 GSPS) digitizers are applied to capture detailed beam-related signals, while universal-sampling-rate (125/500 MSPS) digitizers are employed to record long-term signal variations in a single acquisition. This paper describes the applications of these digitizers and the development of integrated graphical user interfaces for the TPS and TLS control systems.
Paper: THPM069
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM069
About: Received: 29 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM070
Development of a new clock phase shifter for phase measurement at the TPS
2832
The Taiwan Photon Source (TPS) is a 3 GeV synchrotron radiation facility located at NSRRC. Superconducting RF cavities have been installed in the booster and storage rings to ramp and refill electron beam energy. In order to measure the bunch phase of each bunch relative to the RF clock of the accelerator, a bunch phase detector (BPD) system was constructed to support measurement experiments. This detector uses the I/Q demodulator approach to calculate the beam phase. The system supplies a reference clock to the ADC at the RF frequency, along with a signal at three times the RF frequency, to enable calculation of the phase difference between the beam and the reference signal. The system includes a single-board computer (SBC) which is integrated with the control system to implement the remote phase adjustment function to make the operation more convenient. The BPD has been installed in the TPS and can provide measurement data. This paper describes the efforts in implementing this system.
Paper: THPM070
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM070
About: Received: 26 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
THPM071
Synchronous phase measurement and study at the Taiwan Photon Source
2835
A bunch-by-bunch synchrotron phase detector system has been implemented to investigate the synchronous phase behavior of the storage ring at the Taiwan Photon Source. This detector employs I/Q demodulation to cal-culate the beam phase on a bunch-by-bunch basis. The acquired data is integrated into the accelerator control system, visualized through a graphical user interface, and made available for further analysis. Independent component analysis (ICA) is employed to identify under-lying sources. For a trapezoid-like filling pattern, transi-ent beam loading effects are clearly observed in the flat-top region, whereas significant phase variations occur along the sloped edges of the pattern. During the beam decay period, an in-phase synchrotron phase oscillation at 7 kHz is observed, which originates from the rotation frequency of the radio-frequency transmitter. During injection, three distinct modes are identified through ICA decomposition. Among them, the amplitude of the syn-chronous oscillation mode shows a strong dependence on the injected bucket address.
Paper: THPM071
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM071
About: Received: 20 Apr 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
THPM072
The online emittance monitor at Taiwan Photon Source
2839
This study summarizes the X-ray pinhole camera results from two recently constructed diagnostic beamlines. We provide updated emittance and energy spread measurements for the TPS storage ring and implement online measurements for routine operational monitoring.
Paper: THPM072
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM072
About: Received: 19 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM073
The Issue with XBPM2 in the TPS Front End
2842
Two sets of blade-type beam position monitors (XBPMs) are installed in the Taiwan Photon Source (TPS) front-end. The upstream XBPM, referred to as XBPM1, has been calibrated and can calculate the photon beam center position. The downstream XBPM, referred to as XBPM2, encountered difficulties during calibration. It was unable to obtain an effective linear range. Adjustments to the blade spacing and alternative calibration methods were explored to address this issue. These details will be discussed in the article.
Paper: THPM073
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM073
About: Received: 23 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM075
The efforts on beam stability improvement in TPS
2845
This report discusses various efforts to improve beam stability at the Taiwan Photon Source. The Fast Orbit Feedback (FOFB) system is essential for maintaining beam stability in the light source. Considering the trade-off between FOFB reliability and performance, we optimize the FOFB parameters to achieve better orbit stability in the TPS. Occasional spikes in the Beam Position Monitor (BPM) readings are observed in a few BPM pick-ups and it would degrade the efficiency of the FOFB system. The probability of these spikes occurrence could be related to the different filling patterns and beam currents. A schedule for replacing these BPM buttons will be established. Additionally, the effect of various signal processing schemes on the beam is also examined.
Paper: THPM075
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM075
About: Received: 27 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM076
Progress towards longitudinal bunch profile monitor at the Argonne Wakefield Accelerator employing phase diversity electro-optic sampling
2848
Precise measurement of an electron bunch’s longitudinal profile is critical for wakefield accelerators as shaped electron bunches can improve transformer ratios in collinear wakefield acceleration. Electro-Optic sampling of terahertz (THz) radiation from the bunch is one of the most attractive approaches to provide a view into the structure of a relativistic electron bunch due to its non-destructive nature. Recent developments in spectral encoding methods have shown that Phase Diversity Electro-Optic Sampling (DEOS) can accurately retrieve profiles from both sub-picosecond bunches and those requiring long sampling time windows near the traditional resolution limits. We report the progress on DEOS measurements using coherent transition radiation (CTR), as well as simulations of retrieved THz fields from arbitrary shaped electron bunches using various crystal and probe-laser configurations.
Paper: THPM076
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM076
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM077
Measurement of vertical and horizontal emittance via undulator high harmonics at the APS-U
2852
The transition from 3rd to 4th generation synchrotron light sources can primarily be characterized by a significant reduction in horizontal emittance. This enables a nearly uniform transverse X-ray beam profile and a brilliance that approaches the diffraction limit. A consequence of the upgrade to Diffraction Limited Storage Rings (DLSRs) is that the traditional emittance measurement techniques lack the resolution required to accurately measure emittances in the picometer-radian range. At the Advanced Photon Source Upgrade (APS-U), we explore the use of high harmonics of undulator radiation for precise emittance characterization. Previously at the Advanced Photon Source (APS), vertical emittance measurements, validated through SPECTRA simulations, were performed. This drove the desire to measure the horizontal emittance at the APS-U. Simulations performed in SPECTRA and Synchrotron Radiation Workshop (SRW) guide our experimental strategy for characterization. We present measurements of both the horizontal and vertical emittance at the APS-U, including variations across different bunch timing modes. We conclude by discussing the advantages of this approach over traditional methods.
Paper: THPM077
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM077
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
Development of a beam profile monitor based on the YAG:Ce scintillator for a multipurpose beam diagnostic system
In this paper, a multipurpose beam diagnostic system based on a YAG:Ce scintillator is presented. This system was developed in order to measure beam profile, transverse parameters, momentum spectrum, and current of the electrostatic accelerator. The concerning issues in the beam profile monitor design such as image resolution and scintillator temperature distribution have been discussed. In order to estimate the resolution of the scintillator screen, the collision of ideal proton and electron beam with YAG:Ce scintillating screen was simulated using the Geant4 Monte Carlo code. Increasing scintillation temperature will decrease the scintillation optical yield and result in a change in beam profile, so COMSOL software was used to simulate the scintillation temperature distribution under different beam powers. The design procedure, including the handling of heat transfer and charging accumulation issues, as well as estimation and improvement of image resolution, has been investigated. After designing the beam profile monitor based on YAG:Ce,The equipment was provided and manufactured and the beam profile was measured using this diagnostic tool.
Design of a multi-layer ionization chamber
In this paper, a multi-layer ionization chamber is designed for the measurement of 250MeV proton beam profile. The chamber is equipped with 128 X and Y channels, allowing for high-resolution profiling of the proton beam across both transverse axes. Each channel is capable of detecting ionization events, providing precise dose measurements and spatial distribution information. The design incorporates advanced materials and configurations to ensure optimal energy response and accuracy at the specified proton energy. The proposed chamber aims to enhance the accuracy of proton therapy dose verification and monitoring, enabling better patient treatment planning and quality assurance in proton beam therapy.
Design of a novel high-precision beam diagnostic beamline
A novel high-precision beam diagnostic system has been designed for slice emittance and energy spread measurements. The 20-meter diagnostic platform integrates eight quadrupoles, a deflecting cavity, and an energy spectrometer, achieving 100fs temporal resolution in both operational modes through the same beamline layout. The emittance measurement mode provides 50-fold horizontal magnification, while the energy spread measurement mode reaches 1.71 keV theoretical energy resolution through optimized dispersion and screen rotation. Comprehensive error analysis confirms measurement precision of 3.05%±0.69% for relative emittance changes and 4.82±1.35 keV for energy spread variations, demonstrating the effectiveness of this flexible design for high-precision beam diagnostics.
Edge-ML and targeted data processing for high-rate, attosecond XFEL diagnostics
SLAC’s upgraded Linac Coherent Light Source (LCLS-II) promises transformative 1 MHz attosecond X-ray pulse generation. To meet the demands of high-rate attosecond characterization across multiple operational modes at LCLS-II, we showcase the data processing chain for the Multi-Resolution COokiebox (MRCO) detector--a circular array of 16 multichannel plate time-of-flight spectrometers optimized through independently controlled electron flight lenses and dedicated amplifiers for precise electron signal capture. MRCO’s data processing chain integrates analog and digital co-design with targeted edge-machine learning (ML) approaches. Traditional FPGA-friendly algorithms, such as the convolution-based and discrete cosine transform-based peak-finding methods, enable real-time spectral feature extraction. Additionally, ML techniques enable denoising, sub-spike identification, and temporal profile reconstruction, advancing single-shot diagnostics and attosecond resolution. This work lays the foundation for online diagnostics, shot rejection, and feedback to XFEL controls, with implications for time-resolved studies such as X-ray pump X-ray probe experiments.
THPM085
Design and development of a beam scraper system for Siam Photon Source II
2856
This paper presents the development of a beam scraper system for the 3 GeV storage ring of Siam Photon Source II (SPS-II). Beam scrapers are essential for removing halo particles, protecting accelerator components, and managing aperture limitations. The scraper blade material is carefully chosen for its superior thermal conductivity and mechanical strength. The design prioritizes considering wakefield impedance to minimize beam disturbances, incorporates detailed thermal simulations to ensure operational stability, and optimizes the mechanical structure for easy installation and long-term durability. This design approach significantly enhances the performance and reliability of the SPS-II beam scraper system.
Paper: THPM085
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM085
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM086
Improvement of transverse beam size measurement using synchrotron radiation at Siam Photon Source
2859
The Siam Photon Source (SPS) has, for several decades, implemented direct imaging with synchrotron radiation for the measurement of transverse beam size. This paper describes improvements made to the transverse beam measurement system of the SPS storage ring. A synchrotron radiation interferometer system will be integrated for monitoring of beam size alongside the direct imaging system. The system's operations will be controlled and displayed through Python programming. The results from each technique will be comparatively analyzed.
Paper: THPM086
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM086
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
THPM087
Possibilities for performance enhancement of a compact TDS at FLUTE
2862
A compact transverse-deflecting system (TDS) is being commissioned at the test facility FLUTE (Ferninfrarot Linac- und Test-Experiment) located at the Karlsruhe Institute of Technology (KIT). It has been proposed for diagnostics of short electron bunches. The idea of the technique is to use terahertz (THz) radiation, produced by the tilted-pulse front method using a part of the facility’s photoinjector laser, amplified by a sub-mm scale resonator for streaking of the electron bunch. Two types of resonators and their arrays have been studied: inverse split-ring and tilted slit resonator. Since the temporal resolution of this technique depends strongly on the electric field strength in the resonator gap, it would be desirable to increase this field strength. A horn-antenna-like device placed near the resonator has been proposed and simulated for this purpose. Simulations and geometrical parameter optimization have been performed using CST MICROWAVE STUDIO and will be presented in this contribution.
Paper: THPM087
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM087
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM088
Preliminary investigation on single-pixel Schottky diode based ultra-broadband THz detectors with ps-scale temporal resolution for future BCMs
2866
A Terahertz (THz) transition radiation monitor, as part of a Bunch compression monitor (BCM), is implemented for longitudinal bunch diagnostics at FELs such as ELBE, FLASH, or EuXFEL. Pulse energy measurements are typically carried out after each bunch compressor stage using coherent diffraction radiation (CDR) in the THz domain and pyroelectric detectors. For higher repetition rates in the MHz range, complex correction algorithms must be applied to correct signal pileup of the pyro-electric detector output, as well as limited signal-to-noise ratio, which can be overcome by using THz detectors with ultra-flat frequency response up to several THz. This work exhibits preliminary studies on developing an ultra-flat frequency response THz spectrometer. We present the developed single-pixel Schottky diode-based THz detector capable of single-shot measurements with a response time of 28.5 ps and IF bandwidth of $\sim$70 GHz. Further, the simulation result from the Schottky diode parameters is presented.
Paper: THPM088
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM088
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM089
Disentangling sudden beam loss events and fast beam abort system with the RFSoC-BPM at SuperKEKB
2870
In the SuperKEKB/Belle-II experiment, various new physics searches are conducted by colliding 4 GeV positrons and 7 GeV electrons. Future plans aim to significantly increase luminosity, targeting an integrated luminosity 100 times higher than current levels. However, the realization of this goal is challenged by the phenomenon of "Sudden Beam Loss" (SBL), characterized by the abrupt disappearance of the beam within tens of microseconds. As presented at IPAC'24, we developed the RFSoC-BOR (Bunch Oscillation Recorder) system, based on the AMD/Xilinx RF System on Chip (RFSoC). This system enables bunch-by-bunch beam position monitoring and detailed SBL data acquisition. Using the RFSoC-BOR, we analyzed SBL events, identified key contributing factors, and gained insight into strategies for mitigation. Our findings have advanced the understanding of SBL, bringing SuperKEKB closer to higher luminosity operation. Additionally, we are extending the functionality of the RFSoC-BOR to develop a fast beam abort system that improves accelerator component protection. This presentation will cover the role of the RFSoC-BOR in SBL analysis, key insights, and progress on the fast beam abort system.
Paper: THPM089
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM089
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 10 Jul 2025
THPM090
Study of Cherenkov diffraction radiation from radiator with periodic structure in THz-region
2874
We have studied classical radiation from relativistic electrons at a facility, test accelerator as a coherent terahertz source (t-ACTS), the Research Center for Accelerator and Radioisotope Science (RARiS), Tohoku University. Cherenkov radiation is generated when a relativistic charged particle passes through a dielectric medium, while Cherenkov diffraction radiation (ChDR) is emitted when the relativistic charged particle passes near the dielectric medium. In general, the ChDR spectrum is broadband. However, when a periodic structure is used as a radiator, interference effects can monochromatize the ChDR. At t-ACTS, a proof-of-principle experiment in the THz region was conducted using a high-density polyethylene (HDPE) radiator with a periodic structure. We successfully measured ChDR from radiator with periodic structure and achieved narrowband ChDR (NbChDR) in the THz region. This paper will discuss the characteristics of NbChDR in the THz region, as observed at t-ACTS.
Paper: THPM090
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM090
About: Received: 26 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM091
Extinction Monitoring of Pulsed Proton Beams Using FPGA-Based Peak Detection
2878
The Mu2e experiment at Fermilab imposes stringent requirements on the elimination of out-of-time beam in its pulsed proton beam - a requirement known as "extinction". We present a method to measure the out-of-time particle rates to calculate the level of extinction in the inter-pulse gaps. The proposed method utilizes an array of quartz Cherenkov radiators and photomultiplier tubes to detect particles scattered from a vacuum chamber in the M4 transfer beamline at Fermilab. The measurement will employ a new μTCA-based FPGA system for data acquisition and signal processing, utilizing real-time peak detection algorithms to count scattered beam particles. By integrating data over many transfers, the time profile of the out-of-time beam will be resolved to fractional levels relative to that of the in-time beam. These results are compared with G4beamline simulations to validate models of beam transport, dynamics, and extinction, providing critical input for optimizing beam delivery to Mu2e.
Paper: THPM091
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM091
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
Demonstrating a Fisher Information based methodology for optimizing BPM placements in AS2
The next generation Australian Synchrotron project (AS2), is a proposed 4th generation light source, aims to deliver ultra-low emittance $\sim$100 pm-radians and highly coherent, bright light. Constraints on emittance place tight demands on beam optics correction techniques like linear optics of closed orbit (LOCO) and consequently constraints on accurate estimation of the beam centroid along the orbit. In this work, we propose a Fisher Information Matrix (FIM) -based method for optimizing BPM placement. To achieve this, we use the fully differentiable accelerator code Cheetah, which integrates accelerator modelling with automatic differentiation to enable fast simulations and efficient computation of partial derivatives - including the FIM from the second derivative. Using this we derive optimal BPM placements that minimize variance in estimation of the beam centroid parameters for a segment of the AS2 system.
Toward low multiplicity energy controllable beams at the CLEAR facility
We report on tests to achieve low multiplicity (single electron) at the CLEAR facility with a well defined particle energy. This can be achieved by a set of three collimators around a dipole magnet. These collimators reduce the charge of the beam and they give three degrees of freedom, allowing to control the position, angle and energy of the selected particles.
THPM095
Benchmarking of new approach for analyzing transverse beam emittance measurement
2882
A recent analysis of emittance measurements highlighted the limited reliability of tools for precise method evaluation and error calculations. In this paper, a new analysis method is presented with its associated errors calculations. It is evaluated using realistic beam simulations and compared to the linear regression method commonly referenced in the literature. This new analysis method is shown to be easier to implement and provides results with a good confidence interval.
Paper: THPM095
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM095
About: Received: 22 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM096
Top-up safety simulations for Elettra 2.0
2886
A comprehensive program of tracking studies has been carried out to ensure that no train of injected electron bunches can traverse an open beamline during top-up operations at Elettra 2.0. The analysis explored various error scenarios, considering realistic magnetic field variations, trajectory shifts, aperture constraints, and energy deviations. This paper presents the tracking techniques employed, the scenarios investigated, and the proposed interlock systems designed to ensure safety during top-up operations.
Paper: THPM096
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM096
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM098
VSlib: A C++ library for next-generation voltage source control at CERN
2890
The ongoing upgrades to CERN power converters pose new challenges to the converter control hardware that require a next-generation embedded control computer: the Function Generator/Controller 4 (FGC4), currently in development. The hardware is based on an AMD Zynq UltraScale+ MPSoC System-on-Chip (SoC), featuring a quad-core A53 ARM-architecture CPU, with one bare-metal core dedicated to the voltage source control. To fulfil the goal of high-reliability control in this integrated environment, a C++20 library to run on bare-metal, called VSlib (Voltage Source library) has been developed. The library is a toolkit providing all the necessary building blocks for regulation algorithms, as well as communication with other bare-metal and Linux-running cores of the SoC. A dedicated GUI was created to facilitate configuration of library parameters. The main focus was placed on high performance, determinism, and reliability. The library was developed according to best industrial practices, including version control, static analysis, and automated unit testing, with tests against expert models using Hardware-in-a-Loop simulator of a power converter, and continuous deployment.
Paper: THPM098
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM098
About: Received: 14 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 10 Jul 2025
THPM099
Results from validation experiment for three-dimensional spiral beam injection scheme
2894
A three-dimensional spiral beam injection scheme\* has been developed since 2014. This scheme is for accumulating a charged particle beam with relativistic energy in a sub-meter storage ring to realize for the J-PARC Muon g-2/EDM experiment (E34). Prior to the E34 experiment, we conducted a demonstration experiment utilizing 80 keV pulsed electron beam generated by an electron gun\**. The beam passed through a transport line of three rotating quadrupoles and was accumulated in an 80gauss solenoid magnet at the center fiducial volume with a diameter of storage orbit only 24cm. Now we have successfully accomplished (1) a strongly X-Y coupled beam phase space to inject into the axisymmetric solenoid magnetic field, (2) a weak focusing magnetic field potential within the storage region at the center of the solenoid magnet, (3) a pulsed magnetic field kick to guide the beam trajectory into the storage region, and (4) beam diagnosis in the storage area. In this presentation, we will report the experimental results of successful storage in an ultra-compact ring, and improvements for the actual storage ring for E34 based on this knowledge gained from 10 years of demonstration experiments.
Paper: THPM099
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM099
About: Received: 04 Jun 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM100
Optimization of Siam Photon Source storage ring using Badger
2898
Badger is optimization software created for the purpose of real-time accelerator tuning and operation. A range of optimization algorithms are available on this platform, implemented with both graphical and command-line user interfaces. This study shows the improvements in beam size, beam lifetime and related parameters at the Siam Photon Source storage ring following the application of Badger. The optimization results will be presented.
Paper: THPM100
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM100
About: Received: 28 May 2025 — Revised: 29 May 2025 — Accepted: 29 May 2025 — Issue date: 10 Jul 2025
THPM101
Unified differentiable digital twin for the IOTA/FAST facility
2901
As the design complexity of modern accelerators grows, there is more interest in using advanced simulations that have fast execution time or produce insights about accelerator state. One notable example of additional information are gradients of physical observables with respect to design parameters produced by differentiable simulations. The IOTA/FAST facility has recently begun a program to implement and experimentally validate a unified start-to-end differentiable digital twin to serve as a virtual accelerator test stand, allowing for rapid prototyping of new software and experiments with minimal beam time costs. In this contribution we will discuss our plans and progress. Specifically, we will cover the selection and benchmarking of both physics and ML codes, the development of generic interfaces between device models and surrogate or physics-based sections, and the export of the parameters through either a deterministic event loop or a fully asynchronous EPICS soft input/output controller. We will also discuss challenges in model calibration and uncertainty quantification, as well as future plans to support larger proton accelerators like PIPII and Booster.
Paper: THPM101
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM101
About: Received: 29 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM102
High efficiency multi-objective Bayesian algorithm for APS-U nonlinear dynamics tuning
2905
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.
Paper: THPM102
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM102
About: Received: 29 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
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.
Vibration monitoring of water pumps for anomaly detection
In accelerators facilities, unexpected failures of water pumps can lead to overheating, unplanned downtime, and costly repairs. In this study, we present a novel approach for real-time monitoring of water pump vibrations to detect anomalies indicative of impending mechanical failures. We employ simple vibration sensors combined with machine learning algorithms to identify patterns and deviation from normal operating conditions. Implementation of this anomaly detection framework can significantly enhance the operational efficiency and uptime of accelerator facilities by reducing unplanned outages and extending the lifespan of water pump equipment.
THPM106
Multimethod signal processing for comprehensive tune coupling characterization at Canadian Light Source
2909
This study compares Fast Fourier Transform (FFT), Power Spectral Density (PSD), and Wavelet Analysis for detecting tune coupling at the Canadian Light Source (CLS). Data were analyzed for low coupling, 1.4%, and 2.5% high coupling regimes, focusing on frequency identification and amplitude stability in X and Y directions. FFT revealed ~15% amplitude fluctuations, complicating tune identification. PSD provided better stability, with only 4% amplitude variations. Both methods were computationally efficient, with FFT taking, 0.0103 seconds and PSD, 0.0108 seconds per calculation. Wavelet analysis preserved temporal-frequency relationships, revealing delays between X and Y frequencies of 2.38 to 4.77 microseconds in the 1.4% regime and peak periods around 18 microseconds. In high coupling, X frequencies preceded Y frequencies, with dominant frequencies showing higher amplitudes than perturbed ones. These findings demonstrate PSD's stability for tune measurements and Wavelet Analysis's ability to capture temporal dynamics, providing insights to enhance beam stability in accelerator systems.
Paper: THPM106
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM106
About: Received: 23 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM109
Operational results of data-driven automated intensity optimization at CERN’s LEIR
2913
At CERN’s Low Energy Ion Ring (LEIR), high beam intensities are achieved through phase space painting with up to eight multi-turn injections from the linear accelerator Linac3. After each injection, the beam is cooled and stacked in longitudinal phase space using an electron cooler. During beam operation, key parameters such as RF cavity phases in the linac, the LEIR electron cooler gun voltage, and various magnetic field strengths along the transfer line must be frequently adjusted to compensate for the injection performance degradation occurring over time. The primary cause is the aging of the stripper foil, a thin carbon plate which strips off electrons from the passing ions, altering the energy of the beam injected from the linac. Time of flight measurements in the linac and Schottky signals in the ring provide the necessary diagnostics for correcting the performance degradation and can be encoded to provide a state for an optimizer. In this paper, we compare several data-driven methods, such as Bayesian Optimization and Reinforcement Learning for designing an autonomous controller to optimize and maintain injection performance during both beam commissioning and physics runs.
Paper: THPM109
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM109
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM110
Machine learning for the anomaly detection and characterization of the 24 GeV/c proton beam at CERN IRRAD Facility
2917
The accurate assessment of beam quality is the most important aspect in the irradiation facilities operation such as IRRAD at CERN. The Beam Profile Monitor (BPM) sensor system developed for the high-intensity proton beam at IRRAD features minimal particle interaction, improved radiation hardness and higher sensitivity and sampling rate than previous systems. It provides a wealth of high-quality BPM data not available earlier, enabling the development of data processing more advanced than before. To take advantage already today of this upgraded BPM system’s features, we propose innovative Machine Learning (ML) techniques to adapt and improve upon existing DAQ technology. This paper details the application study of (1) autoencoder architectures to perform the automatic pattern recognition and anomaly detection of proton beam profiles, and (2) deep learning techniques to predict relevant beam parameters. We applied this approach to a new dataset (made publicly available) of BPM data taken during the recent runs of IRRAD; our preliminary results demonstrate good performance in comparison to existing methods. This work is a first step towards the "intelligent" irradiation facilities.
Paper: THPM110
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM110
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM111
Characterization of an IRRAD beam profile monitor at the CERN T8 beamline and possible improvements via cross-analysis with multiwire proportional chamber
2921
A new Beam Profile Monitor (BPM) system has been recently developed at the IRRAD Proton Facility to monitor the high-intensity 24 GeV/c proton beam from the CERN Proton Synchrotron accelerator. Thanks to the use of a new sensor manufacturing technology based on the microfabrication of metal nano-layers and updated readout electronics based on a Charge-Sensitive Amplifier with integrated 20-bit ADC and ARM controller, this system features minimal particle interaction, improved radiation hardness and higher sensitivity than earlier solutions. The growing users’ demand for precise irradiation of modern electronics, requiring ever more detailed beam information, is driving the introduction of future IRRAD upgrades, by leveraging on the presence of additional detector, a Multiwire Proportional Chamber, a detailed comparison-based analysis was performed to better characterize the IRRAD BPM system. It allowed us to introduce improvements in beam monitoring via advanced software and data processing. These results are crucial for future improvements at IRRAD by formulating requirements for the profile monitoring of new types of beams in IRRAD, e.g. heavy-ion and low-intensity proton beams.
Paper: THPM111
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM111
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 10 Jul 2025
THPM112
Detecting anomalies in non-static environments: continual learning applied to CERN's kicker magnet
2924
The CERN accelerator complex relies critically on fast injection and extraction processes to transfer particle beams between accelerators via fast pulsed magnets, or kickers. Ensuring high availability is paramount, as the reliability of these systems directly impacts the large number of experiments conducted at CERN. In this paper, we propose to explore Continual Learning (CL) methods, specifically using Variational Autoencoders (VAEs), to develop an anomaly detection system for the fast kicker magnets. By continuously learning from evolving data while retaining prior knowledge, these models will be capable of detecting anomalies without the need for repeated retraining. This approach is particularly relevant for ensuring the reliability and stability of kicker magnets, where early anomaly detection is critical for preventing performance degradation.
Paper: THPM112
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM112
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 10 Jul 2025
THPM113
Trajectory steering for DC beams at the CERN SPS using reinforcement learning based on intensity measurements
2928
The slow extracted beams at the CERN Super Proton Synchrotron (SPS) are transported over several 100 m long transfer lines to three targets in the CERN North Area Experimental Hall. The experiments need intensity fluctuations to be entirely eliminated over the roughly 5 s particle spill, requiring full debunching of the extracted beams. In this environment, secondary emission monitors (SEMs) have to replace the conventional beam position monitoring systems that rely on RF structure, with the intensity difference on split secondary emission foils used to indicate the beam position. Traditional trajectory correction algorithms however fail when the beam ends up on a single foil. This paper summarises successful first tests with reinforcement learning (RL) to learn to correct the trajectory based on foil intensity measurements. The RL agents were trained in simulation and then successfully transferred to the real accelerator environment. Results of the application of the trained RL agents for the alignment of moveable split foils in front of the targets will also be presented.
Paper: THPM113
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM113
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM116
Efficient data-driven model predictive control for online accelerator tuning
2931
Reinforcement learning (RL) is a promising approach for the online control of complex, real-world systems, with recent success demonstrated in applications such as particle accelerator control. However, model-free RL algorithms often suffer from sample inefficiency, making training infeasible without access to high-fidelity simulations or extensive measurement data. This limitation poses a significant challenge for efficient real-world deployment. In this work, we explore data-driven model-predictive control (MPC) as a solution. Specifically, we employ Gaussian processes (GPs) to model the unknown transition functions in the real-world system, enabling safe exploration in the training process. We apply the GP-MPC framework to the transverse beam tuning task at the ARES accelerator, demonstrating its potential for efficient online training. This study showcases the feasibility of data-driven control strategies for accelerator applications, paving the way for more efficient and effective solutions in real-world scenarios.
Paper: THPM116
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM116
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025
THPM120
Application of large language models for the extraction of information from particle accelerator technical documentation
2935
The large set of technical documentation of legacy accelerator systems, coupled with the retirement of experienced personnel, underscores the urgent need for efficient methods to preserve and transfer specialized knowledge. This paper explores the application of large language models (LLMs), to automate and enhance the extraction of information from particle accelerator technical documents. By exploiting LLMs, we aim to address the challenges of knowledge retention, enabling the retrieval of domain expertise embedded in legacy documentation. We present initial results of adapting LLMs to this specialized domain. Our evaluation demonstrates the effectiveness of LLMs in extracting, summarizing, and organizing knowledge, significantly reducing the risk of losing valuable insights as personnel retire. Furthermore, we discuss the limitations of current LLMs, such as interpretability and handling of rare domain-specific terms, and propose strategies for improvement. This work highlights the potential of LLMs to play a pivotal role in preserving institutional knowledge and ensuring continuity in highly specialized fields.
Paper: THPM120
DOI: reference for this paper: 10.18429/JACoW-IPAC25-THPM120
About: Received: 21 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 10 Jul 2025