MC6.T03 Beam Diagnostics and Instrumentation
The contribution of multiple reflections to transition radiation
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A uniformly moving electron passing through a slab induces electromagnetic emission known as transition radiation. The generated rays propagate inside the slab and undergo multiple reflections off the slab boundary. We employ the polarization current method in order to derive the reflectionless solution for an observed radiation intensity and compare it with that of Pafomov which accounts for multiple reflections exactly. We identify the parameters of the set up that reduce the Pafomov solution to a reflectionless scenario. Provided the ultrarelativistic electron, the proper choice of the slab thickness allows the consideration of the reflectionless solution even in the optical range. Furthermore, it is shown that in the x-ray regime the reflections only become substantial when the radiation is incident on the slab boundary at a high angle at which the intensity of the radiation is vastly reduced. Therefore for a slab shaped screen the reflections may be ignored. Nevertheless the identification of the scenarios where reflectionless solution deviates from the Pafomov, could be used to qualitatively describe transition radiation from targets of complex shape.
WEAN1
Measurement techniques using the electron beam profile scanner at the Fermilab Main Injector
1670
This work presents techniques for non-invasive transverse profile measurements of high-intensity proton beams using an Electron Beam Profile Scanner (EBPS). The EBPS utilizes low-energy electrons as a probe to analyze the transverse size of proton beams, allowing for potential analysis on a single-bunch basis. Recent upgrades to the Fermilab Main Injector have enhanced beam power on target to 1 MW, with future developments targeting 2 MW. The higher beam power has increased the demand for non-invasive diagnostics, as invasive methods can disrupt operations. The techniques presented include 1) the slow scan technique, which serves as a proof of concept for the probe beam, 2) the one-shot scan technique for measuring horizontal beam profiles, and 3) the raster scan technique for analyzing horizontal beam profiles as a function of the longitudinal distribution of the beam. The profiles obtained will be crucial for studying and understanding instabilities in high-power, high-intensity proton beams. This will contribute to optimizing the operation of high-power proton accelerators by minimizing beam loss, activation, and damage to both the diagnostics and the accelerator components.
Paper: WEAN1
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-WEAN1
About: Received: 01 Jun 2025 — Revised: 05 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 2025
Development of non-invasive beam diagnostics by quantum optics-based detection
We report our latest progress developing diagnostics using quantum optics-based detection method for determining the spatial properties and current of electron beams. As electrons pass through a dilute vapor of rubidium atoms, their electric and magnetic field perturb quantum states of Rb atoms and change their optical properties. By measuring the polarization rotation due to electron current, we can recreate a 2D projection of the electrons’ magnetic field and determine the electron beam position, size and total current. Our experiment using a 10 ~ 20 keV/110 uA electron beam shows this approach is insensitive to electron energy. Alternatively, using quantum superpositions including highly excited Rydberg states of Rb atoms, we can also measure electric field generated by a travelling electron beam. We reconstructed a 2D profile of a 20 keV/150 uA electron beam and measured its current. These complimentary methods can be particularly useful for real time non-invasive spatial and current characterization of high energy and high current charged particle beams used in various particle accelerators and nuclear physics research.
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-IPAC2025-THPM030
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 2025
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-IPAC2025-THPM034
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM035
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM037
About: Received: 27 May 2025 — Revised: 30 May 2025 — Accepted: 14 Oct 2025 — Issue date: 05 Nov 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-IPAC2025-THPM038
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 14 Oct 2025 — Issue date: 05 Nov 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-IPAC2025-THPM039
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM042
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM043
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM044
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM046
About: Received: 27 May 2025 — Revised: 14 Oct 2025 — Accepted: 14 Oct 2025 — Issue date: 05 Nov 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-IPAC2025-THPM047
About: Received: 02 Jun 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM049
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 05 Nov 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.
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-IPAC2025-THPM057
About: Received: 29 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM059
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM060
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM061
About: Received: 30 May 2025 — Revised: 06 Jun 2025 — Accepted: 06 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM063
About: Received: 23 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM064
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM068
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 31 May 2025 — Issue date: 05 Nov 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-IPAC2025-THPM070
About: Received: 26 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM071
About: Received: 20 Apr 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 05 Nov 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-IPAC2025-THPM072
About: Received: 19 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM073
About: Received: 23 May 2025 — Revised: 14 Oct 2025 — Accepted: 14 Oct 2025 — Issue date: 05 Nov 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-IPAC2025-THPM075
About: Received: 27 May 2025 — Revised: 14 Oct 2025 — Accepted: 14 Oct 2025 — Issue date: 05 Nov 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-IPAC2025-THPM076
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM077
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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 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-IPAC2025-THPM085
About: Received: 28 May 2025 — Revised: 14 Oct 2025 — Accepted: 14 Oct 2025 — Issue date: 05 Nov 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-IPAC2025-THPM086
About: Received: 28 May 2025 — Revised: 30 May 2025 — Accepted: 31 May 2025 — Issue date: 05 Nov 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-IPAC2025-THPM087
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM088
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM089
About: Received: 27 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM090
About: Received: 26 May 2025 — Revised: 14 Oct 2025 — Accepted: 14 Oct 2025 — Issue date: 05 Nov 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-IPAC2025-THPM091
About: Received: 28 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM095
About: Received: 22 May 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 2025
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-IPAC2025-THPM106
About: Received: 23 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 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-IPAC2025-THPM111
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 05 Nov 2025
THPS078
Measuring single-pass dispersion in the LHC
3121
During the LHC Ion Run in 2023, the ALICE detector observed a high level of background that prevented efficient data taking. This background was caused by different ion species generated in the betatronic collimation region that were intercepted by the Tertiary collimator near ALICE Interaction Point. The mass-to-charge ratio of these generated ions causes them to follow a different trajectory to the main ion beam, similar to off momentum particles. Since this is a single-pass effect, the closed dispersion does not describe the trajectory of these ions. Instead, the single-pass or one-pass dispersion is the relevant quantity to measure. In this paper two methods for reconstructing the single-pass dispersion based on the closed orbit and optics data are described. The methods are validated through simulations and applied to real data from the LHC 2023 Ion Run.
Paper: THPS078
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS078
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 2025
THPS079
First prototype measurements with an electro-optical bunch profile monitor for FCC-ee
3125
The future circular electron-positron collider (FCC-ee) is designed for highest luminosity to enhance the precision of high-energy particle physics experiments, spanning energies from the Z pole to the $\text{t}\bar{\text{t}}$ threshold. As outlined in its conceptual design report, high-precision measurements of the longitudinal bunch profile are required across multiple operation modes, which presents key challenges for beam instrumentation. As part of the feasibility study, a concept for an electro-optical (EO) bunch profile monitor has been developed to address these challenges, building on the existing EO beam diagnostic at the Karlsruhe Research Accelerator (KARA) at KIT. The first EO monitor prototype for FCC-ee features a novel crystal-holder design using prisms, enabling a single-pass setup crucial for measuring the long bunches during Z operation. This contribution presents the first measurement results of the EO monitor prototype for FCC-ee, which were obtained in the in-air test stand at the CERN Linear Electron Accelerator for Research (CLEAR).
Paper: THPS079
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS079
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 2025
THPS082
Impact of beam background and jitter on LUXE interaction point
3129
LUXE is an international project that aims to study Quantum Electro-Dynamics processes that occur in the strong field regime. Using the electron beam from the European XFEL, this experiment will perform electron-laser and photon-laser collisions. Beamline simulations are required to understand what beam properties and backgrounds are expected at key locations. The beam optics was design and simulated with MAD-8 and this used to create a BDSIM simulation. To perform high precision interactions it is crucial that the transverse size and position of the electron beam can be measured. The variation of the beam position over time also has impacts on an efficient collision with the laser. This study uses simulated virtual measurement, wire scanning methods, and real measurements at the XFEL to evaluate those parameters. Finally, background from both the upstream beam line and the different dumps must be estimated to ensure that the impacts on the experiment are low enough. This paper present BDSIM simulations with high statistics necessary to evaluate the background. Critical for BDSIM studies is finding optimised ways to do cross-section biasing and final state splitting in the dumps.
Paper: THPS082
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS082
About: Received: 27 May 2025 — Revised: 04 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 2025
THPS083
Investigating beam-induced electron emission from thin wires in PSI proton beams
3133
The emission of electrons induced by beam interaction with thin targets is a phenomenon used to measure various properties of particle beams. The main processes of electron emission are: secondary emission, delta electron production and thermionic emission. The last one is not desired, because the intensity of thermionic electrons is not directly related to beam density profile. A common technique to suppress thermionic emission employs bias potential on the wire, which allows for recapturing of low energy electrons. This study investigates the effectiveness of the bias voltage method for high-brightness proton beams of the HIPA accelerator. Through experiments and simulations, the study aims to better understand the emission spectra, the suppression of thermionic emission, and the effects of beam fields on electron dynamics.
Paper: THPS083
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS083
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 2025
THPS084
LHC BLM-based beam loss pattern recognition algorithm for off-momentum losses
3137
The Beam Loss Monitoring System (BLM) of the Large Hadron Collider (LHC) protects the accelerator against energy deposition from beam losses. One of the most critical moments regarding beam losses is the start of the beam acceleration. During this process, particles outside the bucket will not be captured in the first seconds of the start of ramp thus being lost at the machine aperture. This is expected to be the moment of minimum beam lifetime in the LHC cycle. During Run 3, losses from these off-momentum particles triggered some beam dumps. Several studies are on-going to assess a possible limitation from this loss scenario. This contribution quantifies the beam power lost at that moment and how the losses are distributed along the accelerator by the use of a dedicated BLM loss pattern recognition algorithm.
Paper: THPS084
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS084
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 01 Jun 2025 — Issue date: 05 Nov 2025
THPS087
Raspberry Pi cameras for beam diagnostics at the Frankfurt Neutron Source
3141
The application of Raspberry Pi cameras as cost-effective, versatile beam diagnostic tools is currently being explored at the Frankfurt Neutron Source (FRANZ). These compact imaging systems have been deployed to investigate proton beams at energies of 60 keV and 700 keV, including configurations where cameras are installed both externally and directly inside the accelerator’s RF resonator. Such setups provide opportunities to visualize beam profiles and related phenomena, potentially offering new insights into beam dynamics and cavity conditioning. This contribution will present the latest developments in camera integration, image acquisition, and preliminary image analysis techniques. By showcasing ongoing work and recent findings, we aim to highlight the potential of this approach for enhancing beam diagnostics in future accelerator environments.
Paper: THPS087
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS087
About: Received: 28 May 2025 — Revised: 01 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 2025
THPS089
Measurements for beam size blowup in sudden beam loss events and analysis of the beam loss evolution mechanism
3144
The SuperKEKB electron-positron collider, which aims to achieve the world's highest luminosity, has suffered from "Sudden Beam Loss events (SBL)," in which several tens of percent of the beam current is lost and aborted within a few turns (20-30 µs). We have developed a new turn-by-turn beam size monitor to elucidate the cause and time evolution mechanism of the SBL events from a beam size variation point of view. The beam size monitor has two features: 1) it can measure the beam size variation over dozens of turns just before an SBL-induced beam aborts, and 2) it can measure independently in two different wavelength regions, X-ray and visible light, to ensure redundancy. In the SuperKEKB operation in 2024, we found that the vertical beam size blew up rapidly before a few turns of the abort, up to about ten times larger than the usual beam size. We also found that the size blowup started earlier than the beam position oscillation. In this presentation, we will discuss the mechanism of the beam size monitor we have developed, the analysis results of the measured beam size blowup, and finally, the possible cause and time evolution mechanism of the SBL events.
Paper: THPS089
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS089
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 2025
The contribution of multiple reflections to transition radiation
A uniformly moving electron passing through a slab induces electromagnetic emission known as transition radiation. The generated rays propagate inside the slab and undergo multiple reflections off the slab boundary. We employ the polarization current method in order to derive the reflectionless solution for an observed radiation intensity and compare it with that of Pafomov which accounts for multiple reflections exactly. We identify the parameters of the set up that reduce the Pafomov solution to a reflectionless scenario. Provided the ultrarelativistic electron, the proper choice of the slab thickness allows the consideration of the reflectionless solution even in the optical range. Furthermore, it is shown that in the x-ray regime the reflections only become substantial when the radiation is incident on the slab boundary at a high angle at which the intensity of the radiation is vastly reduced. Therefore for a slab shaped screen the reflections may be ignored. Nevertheless the identification of the scenarios where reflectionless solution deviates from the Pafomov, could be used to qualitatively describe transition radiation from targets of complex shape.
THPS091
Beam instrumentation at the multi-turn linac passages of MESA
3148
We will present the status of the beam instrumentation at MESA. To put MESA into operation various diagnostic systems are necessary. To optimize the beam the position and phase with respect to the accelerating RF needs to be optimized to be able to recirculate the beam for multi-turn operation or ERL mode respectively. On the other hand, an absolute beam current measurement is necessary. This can be achieved with a DCCT on the linac axis. The instrumentation will be installed very close to our cryo modules and needs to fulfil the excellent vacuum requirements for superconducting RF.
Paper: THPS091
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS091
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 2025
THPS093
Multichannel system for measuring the phase of acceleration and other parameters of beams in a cyclotron
3151
Diagnostics of charged particle beams is an important area in the field of accelerator technology. Non-destructive methods of beam diagnostics are becoming increasingly popular, as they allow measurements to be taken without changing the beam parameters. This is particularly valuable when studying continuous processes, the results of which can be distorted when using traditional diagnostic methods. Pickup electrodes are devices used for non-destructive diagnostics of charged particle beams. They are thin metal plates located along the axis of the beam motion. When a particle beam passes near a pickup electrode, it creates an electrical signal that is proportional to the beam current. This signal can be processed and analyzed using special equipment and software. A multichannel modular system with expandability has been developed to measure particle acceleration parameters, specifically the phase distribution during movement in the accelerator chamber, coordinates relative to the median plane and other parameters. The paper presents the results of testing the system at the DC-280 cyclotron at FLNR JINR and SSC at IThemba LABS.
Paper: THPS093
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS093
About: Received: 27 May 2025 — Revised: 02 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 2025
THPS094
Characterisation of the foreseen turn-by-turn beam position instrumentation for the cSTART storage ring
3154
The KIT cSTART project (compact storage ring for accelerator research and technology) aims to demonstrate injection and storage of a high intensity ultra-short bunch using the FLUTE LINAC, as well as a laser-plasma accelerator (LPA). cSTART is planned to operate with a wide range of demanding parameters, such as bunch charge, bunch length and energy spread (from the LPA), making it extremely challenging for the choice of beam diagnostics with large dynamic ranges that are capable of operating within specifications. Moreover, turn by turn measurements are necessary in the cSTART storage ring as bunch characteristics are expected to dramatically change within a single turn. In this paper, we will describe the planned beam diagnostics system of the cSTART storage ring focusing on the turn-by-turn signal processing and reporting on characterization tests which were performed.
Paper: THPS094
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS094
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 2025
THPS095
New all-digital camera setup at the Karlsruhe Research Accelerator
3158
Until recently, the Karlsruhe Research Accelerator (KARA) located at the Karlsruhe Institute of Technology (KIT) was using analog cameras to monitor fluorescence screens. By now all cameras have been replaced by digital cameras directly connected via ethernet, making it possible to directly integrate them into our EPICS-based control system. The new control system integration also provides for a better continuous statistical analysis and comparison of camera pictures. This paper presents an overview of the new setup, including the post-processing integration making use of Python.
Paper: THPS095
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS095
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 2025
THPS097
Minimizing disturbance in ion beam profiling with PEPITES monitor
3162
In the field of beam diagnostics for radiotherapy, accurate dose delivery relies on ultra-thin, linear and radioresistant monitors to minimize beam scattering and achieve precise profiling. The first PEPITES prototype monitor features two segmented cathodes, each paired with a high-voltage-biased anode. This latter effectively captures secondary electrons generated by the cathodes when they interact with the beam, enabling the detection of a measurable signal. The Water Equivalent Thickness (WET) of this design is approximately 10 μm*. To achieve efficient profiling of the charged particle beam when the monitor is positioned several meters upstream of the patient, we developed a thinner design. This configuration features two anodes positioned outside the beam path, reducing by half the amount of material that interacts with the beam, thereby minimizing beam disturbances. Both, the previous and the updated PEPITES monitor designs were recently tested at CNAO,Italy. Measurements were successfully conducted using a 115 MeV carbon ion beam at varying high-voltage power. These results will be presented and compared to demonstrate the enhanced efficiency of the upgraded PEPITES version.
Paper: THPS097
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS097
About: Received: 01 Jun 2025 — Revised: 02 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 2025
THPS098
Enabling arbitrary correlations in beam phase space via curve matching
3166
Beam manipulations require precise control of phase space correlations. Gwanghui's previous work introduced a method for generating arbitrary correlations using Fourier series and cosine sums with transverse wigglers. However, accurately controlling the wigglers to match a desired correlation curve remains challenging, as it involves optimizing parameters like amplitude, phase, and period. Existing optimization methods are computationally intensive and prone to local minima. We address these limitations with a deterministic gradient-based optimization process. Using a differentiable error function, we efficiently perform gradient backpropagation to identify optimal parameters. To minimize the number of wigglers while maintaining accuracy, we adopt a recursive strategy: starting with a single wiggler and iteratively adding one at a time, using results from prior steps as seeds. This approach accelerates optimization and reduces computational demands. Building on this method, we design a feedback control strategy for real-time correlation generation with transverse wigglers, enabling precise, flexible beam manipulation and new possibilities in accelerator physics.
Paper: THPS098
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS098
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 2025
Longitudinal phase space measurement using a corrugated structure at the PAL-XFEL
We present the experimental results of the longitudinal phase space (LPS) measurement using a corrugated structure at Pohang Accelerator Laboratory X-ray Free-Electron Laser (PAL-XFEL). The electron beam, passing the corrugated structure, generates the wakefield, which streaks the beam horizontally. The dipole magnet following the corrugated structure disperses the streaked beam vertically. By analyzing the transverse distribution observed at the screen monitor after those components, the electron beam LPS can be characterized. The LPS after the FEL process can also provide the FEL temporal profile, which is the valuable information for the accelerator optimization as well as the user experiments. In this paper, we present the preliminary experimental results for the characterization of the electron beam LPS and FEL profile.
Advancements in RadiaBeam’s multi-dimensional bunch shape monitor: updated testing results and improvements
The Bunch Shape Monitor (BSM) is a versatile diagnostic device designed to measure longitudinal beam parameters, which are essential for the operation and development of high-intensity linear accelerators. However, these measurements remain challenging for proton and ion beams at non-relativistic energies. RadiaBeam has developed an enhanced BSM prototype with several key innovations to improve performance. These include a focusing field between the wire and entrance slit for improved collection efficiency, a redesigned microwave deflector for enhanced beam linearity, and a moving mechanism enabling both transverse profile and longitudinal measurements. Following the initial tests at the Spallation Neutron Source (SNS) presented last year, this work details updated testing results including characterization and optimization, and additional component improvements based on the beam tests conducted at the SNS facility.
THPS103
Optical electron beam diagnostics at the Novosibirsk FEL
3170
We present an overview of recent and upcoming enhancements to the optical electron beam diagnostics stations at the Novosibirsk Free Electron Laser (FEL) facility. These diagnostic stations are designed to measure key beam parameters, including beam energy spread, length and emittance, at the third FEL of Novosibirsk FEL. Currently, the stations for measuring electron beam energy spread and undulator radiation spectrum are in the commissioning phase, with initial results already obtained. The new optical diagnostics are essential for the precise tuning of the magnet system used in electron outcoupling experiments. This paper provides a comprehensive overview of the new diagnostic systems, discusses the preliminary measurement results of beam parameters, and outlines the experiments planned for the near future.
Paper: THPS103
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS103
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 2025
THPS104
Development and testing of an autocorrelator for measuring the duration of picosecond pulses of near infrared radiation
3174
The paper presents a design of an autocorrelator manufactured to measure the duration of infrared picosecond pulses of radiation from the 3rd laser of the Novosibirsk Free Electron Laser facility, as well as the results of testing the autocorrelator when measuring the duration of picosecond pulses in the visible range. The results and future plans for future experiments using developed autocorrelator
Paper: THPS104
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS104
About: Received: 28 May 2025 — Revised: 03 Jun 2025 — Accepted: 05 Jun 2025 — Issue date: 05 Nov 2025
THPS105
Development of CT monitor to measure the stacking beam current in the FETS-FFA test ring
3177
The FETS-FFA will be a proof-of-principle Fixed Field Alternating gradient accelerator (FFA), to demonstrate the feasibility of these machines to drive megawatt-class spallation neutron sources, such as the proposed ISIS-II. It will accelerate protons from 3 to 12 MeV, and demonstrate high-intensity operation through large space charge tune shift. Beam stacking takes advantage of the static magnetic fields and large momentum acceptance of an FFA, to overcome space-charge intensity limitations by combining beams at their highest energy. Four coasting beams are expected to be stacked over 80 ms, which demands an intensity monitor sensitive to coasting beams over this time. Conventional DC Current Transformer's (DCCT's) have proven difficult to develop for a large aperture, so a single inductive core equipped with a Negative Impedance Converter (NIC) amplifier is being developed to provide a time constant of 1 second. This paper will present a feasibility study of this Current Transformer(CT), as well as bench measurements with a large-aperture FT3M FINEMET core and prototype NIC.
Paper: THPS105
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS105
About: Received: 26 May 2025 — Revised: 02 Jun 2025 — Accepted: 03 Jun 2025 — Issue date: 05 Nov 2025
THPS107
Substrate material studies for PCB-based electro-optical bunch arrival-time monitors for XFELs
3181
The all-optical synchronization system used in many X-ray free-electron laser facilities (XFELs) relies on electro-optical bunch arrival-time monitors (EO-BAM) for measuring the single bunch arrival time with regards to an optical reference. An upgrade of the established EO-BAM is intended to achieve a sensitivity that enables stable operation with bunches down to charges of 1 pC, or to significantly increase the resolution in normal operation. Therefore, the pickup structure, the RF path and the electro-optical modulators are undergoing a fundamental redesign. The novel concept of the pickup structure comprises planar pickups on a printed circuit board (PCB) with integrated combination network and a bandwidth of up to 100 GHz. The theoretical jitter charge product of the preliminary concept has been estimated to be in the order of 9 fs pC and the concept was proven experimentally with a 67-GHz demonstrator at ELBE. In this contribution, we compare ceramic and glass substrates in terms of radiation hardness, sensitivity, and manufacturing capabilities. The achievable bandwidth and sensitivity are influenced by material losses and varying tolerances due to different fabrication methods.
Paper: THPS107
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS107
About: Received: 28 May 2025 — Revised: 31 May 2025 — Accepted: 03 Jun 2025 — Issue date: 05 Nov 2025
THPS108
Measurements of dark current and breakdown phenomena using Faraday cups at the Xband Laboratory for Accelerators and Beams (XLAB)
3185
Two CLIC TD24 accelerating structures, manufactured by CERN, are being tested on the high gradient 12 GHz RF test stand at XLAB. Installed at the end of 2024, these are the first devices to be tested at XLAB. Testing aims to verify that following conditioning they can be reliably operated at accelerating gradients of 100 MV/m. The conditioning process involves slowly increasing the peak RF power and pulse length input to the structure. The peak accelerating gradient at which a structure can operate reliably is limited by electrical breakdown. As conditioning progresses the likelihood a that a breakdown will occur decreases. When a breakdown occurs significant charge is emitted by the structure. Considerable progress has been made in the development of the theory of breakdown formation and the underlying interaction mechanisms. Accurate measurements of breakdown phenomena are required to test these understandings. Faraday cups installed upstream and downstream of the structures and connected to high resolution digitisers are employed to measure the behaviour of the breakdown current emissions and dark current. The results of these measurements are presented here.
Paper: THPS108
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS108
About: Received: 28 May 2025 — Revised: 04 Jun 2025 — Accepted: 04 Jun 2025 — Issue date: 05 Nov 2025
THPS109
Non-destructive measurements of non-relativistic ion beam bunch shapes at RAON
3189
Characterizing the longitudinal bunch profile is crucial for understanding beam dynamics and ensuring optimal accelerator performance. To address these needs, Capacitive Pick-Up type Bunch Shape Monitors (CPU-BSMs) were developed at the Institute for Rare Isotope Science (IRIS). These devices non-destructively measure the longitudinal bunch shapes of non-relativistic, nanosecond-scale ion beam bunches. Initial feasibility tests were conducted at a 30 MeV cyclotron to verify the performance of the CPU-BSMs. Subsequently, in 2024, the CPU-BSMs were employed during Nuclear Data Production System (NPDS) beam commissioning at the Rare Isotope Accelerator complex for ON-line experiments (RAON) to characterize both the longitudinal bunch shapes and the beam energy values. In this presentation, we will report the experimental results obtained using the CPU-BSMs during the NPDS beam commissioning at RAON.
Paper: THPS109
DOI: reference for this paper: 10.18429/JACoW-IPAC2025-THPS109
About: Received: 06 Jun 2025 — Revised: 14 Jun 2025 — Accepted: 14 Jun 2025 — Issue date: 05 Nov 2025
Beam profile monitor using thin gas sheets
Transverse beam profile diagnostics for high intensity beams are very challenging as material inserts are untenable. An alternative single shot beam diagnostic was studied, and developed, that consists of a thin sheet of gas. When a charged particle beam traverses the gas sheet, the neutral particles are ionized. The ionization products are then imaged on a monitor and the time of flight is recorded. Based on the specific ionization mechanism at play, the transverse beam profile of the beam can be reconstructed. An experiment at low beam energy was performed at UCLA, and demonstrated the basic concept for impact ionization. Future steps include demonstrating the concept for higher intensity beams as well as technical system modifications to improve the utility in large scale facilities.
An effective method for crossbar-switch interference suppression based on WPT in beam position measurements of HLS II
There are 32 electron beam position processors used for beam position measurement in the storage ring of Hefei Light Source(HLS II), the crossbar-switch(CS) of processors must be operation for RF channels compensation and long-term stability. The turn-by-turn(TBT) and fast acquisition(FA) beam position signals would suffer from the CS interference like harmonics and artifact when the CS is operation. In this paper, an effective method based on wavelet packet transform(WPT) is proposed to suppress the CS interference without distorting actual TBT and FA signal. This method starts with the wavelet packet decomposition of the contaminated TBT signal first, then wavelet coefficients are further processed, and finally the processed coefficients of whole subbands are reconstructed through filter banks to obtain the clean TBT signal. As a result, the relatively slow rate of clean and undistorted fast acquisition(FA) signal is obtained through partial reconstruction. Experiment results with real TBT signals demonstrate the effectiveness of the proposed method, and also show that the proposed method does not distort the actual TBT and FA signal while suppressing the CS interference.