MC03: Beam Position Monitors
WEAC01
Analysis of a phase modulated interferometric Electro-Optic BPM at the CERN SPS
581
The Electro-Optic Beam Position Monitor (EO-BPM) is a new diagnostic tool being developed to enhance the intra-bunch transverse beam position monitoring in the High Luminosity LHC at CERN. This EO-BPM has been installed in the Super Proton Synchrotron (SPS) since 2024. The Pockels effect in lithium niobate crystals is exploited to detect the propagating electric field from passing proton bunches, enabling measurement of beam position and intra-bunch instabilities. Light is conveyed from a remote laser via optical fibres to a Mach-Zehnder interferometer formed between two waveguide pick-ups. The rapid response of the EO-BPM enables intra-bunch turn-by-turn measurements. Data recorded over a range of beam conditions have been studied to characterise its performance, stability, and sensitivity. This paper presents the latest data collected from the SPS and discusses the analysis and future development of the EO-BPM.
Paper: WEAC01
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEAC01
About: Received: 03 Sep 2025 — Revised: 07 Sep 2025 — Accepted: 11 Sep 2025 — Issue date: 20 Jan 2026
Design, characterization, and validation of a pulsed RF burst source for In-situ beam position monitor calibration
Beam Position Monitors are the essential diagnostics tools in any accelerator facility. They enable precise beam orbit measurements with nanometer-level resolution which are crucial for the operation of modern linac-based Free Electron Lasers and future linear colliders. In this work we present the development and implementation of a pulsed RF burst source synchronized with accelerator timing for BPM calibration. This source was installed and characterized at the ATF2 facility in KEK, Japan. The system injects tailored RF pulses into the BPM cavity via one of the two output ports present for each axis. With the capability to adjust frequency and pulse width, to emulate beam pulses, the system demonstrated nearly complete cancellation of beam-generated signals when the injected RF pulse overlapped with the beam pulse. This source has the potential for in-situ BPM calibration without relying on motion systems or "dog-leg" orbit bumps. Beyond calibration, it provides a method to mitigate static signal contributions caused by cavity misalignments and shows potential for compensating wakefield effects, offering a versatile tool for improving beam diagnostics and accelerator performance.
WEDC02
Sub-micron ultra thin SiC free standing membranes for soft X-rays beam monitoring
604
Conventional X-ray beam monitors, such as gold meshes and conductive diamond films, often suffer from significant drawbacks, as diffraction effects, non-uniform transparency, low signal levels, and poor spatial resolution, particularly when applied to soft and tender X-ray beams. To address these limitations, we explore the use of ultra-thin (<2 µm) free-standing Silicon Carbide (SiC), developed by SenSiC GmbH, membranes as in-line, minimally invasive beam position monitors*. These devices offer high lateral resolution and minimal beam perturbation, making them particularly suitable for synchrotron radiation applications. Preliminary beam tests were conducted at the NanoMAX beamline (MAX IV) using highly focused (<1 µm FWHM) soft X-ray beams. SiC devices with 4-quadrant layouts demonstrated clear beam detection capability, though limitations emerged at the quadrant interfaces due to charge collection losses and charge multiplication under high electric fields. These effects were further investigated using Sentaurus TCAD simulations, which highlighted the potential for optimized sensor geometries to mitigate such issues. Results from a related SiC membrane intensity monitor, tested at the PTB four-crystal monochromator beamline at BESSY II demonstrated compatibility with tender and hard X-rays**. This device features a 3 mm diameter membrane consisting of a 0.3 µm p⁺ layer, 1.5 µm n⁻ active region, and a 370 µm n⁺ substrate, with Al contacts. Transmission tests in the 1.75 - 10 keV range confirmed excellent transparency (up to 97.55%) and uniform photocurrent response under 8 keV raster scans. The measured photocurrent at zero bias was 0.586 nA with 86% charge collection efficiency. Together, these results highlight the promising role of sub-2 µm SiC membranes for high-precision, in-line monitoring of X-ray beams across a wide spectral range, with ongoing developments targeting even thinner devices for optimized performance in soft X-ray applications.
Paper: WEDC02
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEDC02
About: Received: 02 Sep 2025 — Revised: 10 Sep 2025 — Accepted: 11 Sep 2025 — Issue date: 20 Jan 2026
Summary of the workshop on BPMs buttons for synchrotron light sources
In the context of building the next generation of synchrotron light sources, significant effort has been directed towards developing BPM buttons. The design of these components needs to consider several factors related to the miniaturization of the beam pipe and the broadening of the beam spectrum, while still guaranteeing high resolution for commissioning and feedback purposes. A workshop was held in December 2024 at ALBA light source organized in collaboration with DESY, aiming to bring together experts from various light sources to share their experiences on the different stages of the deployment process, from simulation to manufacturing and characterization. This presentation reviews the key topics presented at the workshop.
WEPCO02
Study of XBPM diagnostic parameters in the TPS frontend
612
The XBPM installed in the TPS frontend determines the center position of the photon beam using four CVD diamond blades. The combination of XBPM and upstream/downstream EBPM readings of the insertion device enables verification of the photon beam’s alignment along the correct trajectory. Significant changes in the beam position or profile, as well as prolonged periods without recalibration, may cause the XBPM measurement data to lose its reliability. Therefore, evaluating the reliability of the XBPM measurement data is of critical importance. By analyzing the deviation between the theoretical and measured blade intensities and calculating the standard deviation of the similarity percentage among the four blades, a reliability indicator is established. The variation of this indicator is analyzed under different conditions and compared with the corresponding Q values.
Paper: WEPCO02
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO02
About: Received: 29 Aug 2025 — Revised: 08 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPCO03
Results of HESR BPM Testing
615
For the HESR diagonally cut BPMs were designed, with 64 manufactured and tested with a purpose-built BPM test-stand. This test-stand had to host BPMs of various lengths, the overall length of the complete vacuum system varies from 450 mm to 1585 mm. For all BPMs several properties, e.g. the geometric factors or the electrical center in relation to the geometric center, were measured utilizing the test stand. The results of these measurements will be presented together with the challenges resulting from the design choices made for the layout of the test stand.
Paper: WEPCO03
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO03
About: Received: 06 Sep 2025 — Revised: 10 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPCO06
Performance analysis of the RF analog frontend for Diamond–II electron beam position monitors
627
Diamond-II is a major upgrade to the current synchrotron facility, Diamond Light Source. The low emittance electron beam requires more stable, low drift beam position mon- itor electronics which are also essential for the Fast Orbit Feedback system. This paper presents simulated results of the analog frontend for the electron beam position monitors. This work aims to deliver an analog frontend with stable gain and high linearity that meets the dynamic range and noise figure requirements effectively to capture beam positions for single and multi-bunch operation. Performance evaluations have been conducted using the SystemVue simulation suite.
Paper: WEPCO06
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO06
About: Received: 03 Sep 2025 — Revised: 04 Sep 2025 — Accepted: 08 Sep 2025 — Issue date: 20 Jan 2026
WEPCO07
Fast beam-based alignment of BPMs and quadrupole magnets for SPring-8-II
630
In modern low-emittance electron storage rings, precise beam orbit control is crucial to ensure the beam passes through the magnetic center of each high-gradient multipole magnet, with an accuracy of 10 μm or even better. Accurate alignment of a BPM with the center of the neighboring magnet is imperative, a critical requirement for SPring-8-II. With a total of 340 BPMs, efficient beam commissioning of SPring-8-II necessitates a fast beam-based alignment (BBA) method. To assess the feasibility of this method, we conducted a fast BBA experiment at the current SPring-8 storage ring utilizing new BPM readout electronics based on MicroTCA.4, enabling a data acquisition rate at 10 kHz. We varied the strength of a quadrupole magnet adjacent to a BPM head connected to the new fast readout. We scanned the electron beam across the quadrupole center by adjusting a steering dipole magnet. The BPM offset from the quadrupole center was then determined by analyzing data from all BPMs connected to the fast readout. This contribution will detail the proposed fast BBA procedure for SPring-8-II and present the results obtained from the feasibility test at the existing SPring-8 storage ring.
Paper: WEPCO07
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO07
About: Received: 05 Sep 2025 — Revised: 06 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPCO09
Bunch by bunch measurement at the HEPS by oscilloscope
637
By directly sampling the BPM signals with a high sampling rate oscilloscope, the bunch-by-bunch position and phase were calculated. With the help of injection trigger signal, oscilloscope was utilized to capture the injection process. The energy mismatch of the injection transient process and the residual oscillation of the injection bunch were studied. The longitudinal tune and oscillation amplitudes can be inferred. The bunch-by-bunch transverse position and longitudinal phase were analyzed by principal component analysis (PCA). The method also can be used to study the instability of the coupled bunches.
Paper: WEPCO09
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO09
About: Received: 03 Sep 2025 — Revised: 10 Sep 2025 — Accepted: 11 Sep 2025 — Issue date: 20 Jan 2026
WEPCO10
Button BPM development and prototyping for ALBA II
641
As part of the ongoing ALBA II upgrade, which aims to significantly enhance the performance of the ALBA Synchrotron Light Source, a new design for button Beam Position Monitors (BPMs) is under investigation. In this contribution, we present the results of a characterization study conducted on button prototypes supplied by two different manufacturers. Furthermore, we introduce the preliminary design of an alternative button BPM intended for direct welding to the copper vacuum chamber of the upgraded machine.
Paper: WEPCO10
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO10
About: Received: 02 Sep 2025 — Revised: 08 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPCO12
Development of a rectangular diagonal cut-plane BPM for the CSNS-II injection upgrade
645
As part of the CSNS-II upgrade, an improved injection scheme will be implemented to mitigate the space charge effect. To precisely measure the transverse beam position during injection, painting, and storage in the Rapid Cycling Synchrotron (RCS), a large-aperture (260 mm × 180 mm) Beam Position Monitor (BPM) is essential. The rectangular cut-plane BPM was selected for its excellent linearity over a large area and high signal-to-noise ratio (SNR). Due to limited space in the injection section, the BPMs must be integrated into the AC steering magnet. To prevent thermal heating from eddy current flow, a rib structure has been incorporated into the BPM's outer body. The BPM was designed using numerical simulation codes and subsequently manufactured. This paper details the simulation, design, and calibration results of the diagonal cut-plane BPM.
Paper: WEPCO12
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO12
About: Received: 03 Sep 2025 — Revised: 08 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPCO14
Spiral beam position monitor for heavy ion beams
649
Our heavy ion beams are slow, short, and thick. For such beams, spiral beam position monitors(BPMs) are expected to provide good linearity and multiple information readouts despite their small size. At the RIKEN Nishina Center, various ion beams are accelerated using linacs and cyclotrons. However, the beams handled are slow enough compared to relativistic speeds, the bunch length is only about the same as the electrode size, and the beam diameter may be close to the electrode spacing. Conventional “diagonal cut” or “cosine two-theta cut” (for quadratic moments) BPMs produce deviations in wave height*. To solve this problem, it is expected that the wave height deviation can be eliminated by cutting the electrode in a spiral shape. Furthermore, by cutting in a spiral shape, multiple cuts can be placed in one BPM, and it is expected that beam intensity, horizontal position, vertical position, and second moment can be read out at a single location. The performance shown by simulations of the spiral BPM and the development of a prototype will be presented.
Paper: WEPCO14
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO14
About: Received: 03 Sep 2025 — Revised: 09 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
Innovative resistive X-ray beam position monitors based on Silicon Carbide free-standing membrane
Solid State X-ray beam position monitors (XBPMs) are an established reality for in-line, real-time monitoring for X-ray beams. Commercial products are available in different materials, such as diamond (CIVIDEC, DECTRIS) and Silicon Carbide (SenSiC GmbH)*. One issue related to this class of devices is the presence of a separation cross in the center of the device, used to obtain four independent diodes to reconstruct the position of the beam. When dealing with monochromatic highly focused beams, diffraction effects could occur. To overcome this issue, a device inspired by Position Sensitive Diodes (PSD) is currently under study by SenSiC. This device, named “resistive-XBPM”, consists of a thin (1 um – 10 um), 5mm wide, 4H-SiC single-crystal free standing membrane. An additional thin resistive layer allows, for the four metallic contacts on the edges of the device, to collect charge which is proportional to the position of the beam onto the surface of the device. A dedicated electronic system has been optimized to have the simultaneous reading of the four channels, thus achieving real-time reconstruction of the beam position without the limits of the “standard” XBPM-type sensors.
Theoretical and experimental Investigation, and resolution optimization, of Semiconductor-Based Sensors for Non-Fully Intercepting Whitebeam Monitoring of Synchrotron Beams
In this study we present an extensive theoretical investigation, and lateral resolution optimization, into the use of semiconductor-based sensors (*semicon-sensors*) for real-time monitoring of high-intensity synchrotron whitebeams. Leveraging *internal photoemission*, these sensors can give critical advantages over conventional metal-based blade monitors that rely on *surface photoemission*[1]. Notably: (i) *semicon-sensors* generate signals up to three orders of magnitude higher, unaffected by surface contamination; (ii) they can intrinsically suppress low-energy background from bending magnet radiation, greatly improving signal fidelity[2]; (iii) through a novel optimization strategy termed *harmonic-tuning*—which uses spectral filters to selectively enhance detection of specific harmonics from insertion devices—*semicon-sensors* can achieve up to 10× superior spatial resolution. These capabilities enable precise, stable beam diagnostics upstream of monochromators in modern 4th-generation synchrotron facilities. At the conference, we will present comparative modelling results across multiple beamlines, facilities and gap/K-values, demonstrating/establishing performances gains. Furthermore we will present first experimental results of these sensors tested at the Swiss Light Source (SLS) in Switzerland and at IHEP synchrotron in China
Functionalization of SiC diodes for soft X-ray optics
In scanning transmission X-ray microscopy (STXM) beamlines, precise control of X-ray beam position and intensity (I₀) is crucial to minimize imaging artefacts and improve spectral quality. However, limited working distances in STXM setups restrict the integration of conventional diagnostics. To address this, we have developed a center-stop-based Silicon Carbide (SiC) device that integrates beam position sensitivity directly into the optical path, by functionalizing the order sorting aperture (OSA). The device was fabricated from a 20 µm thick single-crystalline SiC membrane using plasma focused ion beam (PFIB) lithography, enabling accurate microstructuring while preserving front-side electrode integrity. Live recording of beam position and I₀ during measurements is enabled through the 4-sector diode geometry patterned around the center stop. Validation experiments at the PolLux beamline (Swiss Light Source) demonstrate the device’s suitability for real-time correction of beam-induced artefacts in next-generation STXM. Additional fabrication details and characterization will be presented at the conference
WEPCO20
Development of Novel, Radiation-Hard, Ultra-Compact Active Beamstops with Integrated 4-Quadrant X-ray Sensors for Scattering Experiments on High-Brilliance Undulator Beamlines
659
SenSiC GmbH, a spin-off from the Swiss Light Source (SLS), has developed a new class of beamstopper sensors, termed Beamstopper Integrated Sensors (BIS)[1,2], based on Silicon Carbide (SiC) semiconductor technology. Using custom processing and assembly methods, BIS devices achieve ultra-compact footprints below 1 mm and are designed for both real-time intensity monitoring and four-quadrant beam position sensing. The choice of SiC enables extreme radiation hardness and intrinsic insensitivity to visible light, enhancing sensitivity and signal fidelity by suppressing stray light contributions. BIS sensors have been successfully validated in operational environments: intensity-monitoring devices were tested at the SLS, while position-sensitive variants were deployed at MaxIV. These results demonstrate the robustness and precision of the BIS technology, offering a compact, radiation-resistant solution for integrated beam diagnostics in high-brilliance synchrotron beamlines.
Paper: WEPCO20
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO20
About: Received: 12 Sep 2025 — Revised: 22 Sep 2025 — Accepted: 24 Sep 2025 — Issue date: 20 Jan 2026
WEPCO25
SOLEIL II BPMs development progress
676
SOLEIL II is the low emittance upgrade project for Synchrotron SOLEIL, targeting an emittance of ~80 pm.rad. The new lattice includes 196 Beam Position Monitors (BPM) distributed in 3 different types depending on the vacuum chamber diameter. To ensure consistent signal levels across varying pipe diameters, two button sizes were selected: 6 mm diameter for 16 mm beam pipes, and 7 mm diameter for the 20 mm and 24 mm sections. To optimize the BPM impedance, button shape is conical. Electromagnetic and thermal simulations have been conducted to validate the proposed designs. In parallel, prototypes have been installed and tested on the existing machine to confirm the simulation results and validate the design. This paper summarizes the simulation outcomes, and the test results obtained on the current machine.
Paper: WEPCO25
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO25
About: Received: 03 Sep 2025 — Revised: 09 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPCO26
First measurements of a prototype stripline BPM for PETRA IV comparison with simulation
680
We present signal and thermal measurements from the first prototype of a stripline Beam Position Monitor (BPM) intended for the PETRA IV synchrotron ring [1]. The monitor was installed at the PETRA III testbed for evaluation and compared against CST Studio Suite [2] simulation results. Initial measurements revealed unexpected signal oscillations and significant heating (up to 135 °C), which were not reproduced in ideal models. For a smooth beam pipe, the expected power loss based on the wake-loss factor would only be 5 W. Including mechanical details such as flanges and copper gaskets in the simulation revealed cavity-induced resonances, which increased the power loss up to 96 W. The updated model showed good agreement with the measured signals in both time (TD) and frequency domains (FD) as well as with thermal data. Replacing the gasket with a RF-sealing variant lowered the measured temperature to 65 °C. This study highlights that multiple mechanical and electromagnetic factors must be understood and included in simulations to predict beam-induced effects in high-frequency diagnostics accurately.
Paper: WEPCO26
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO26
About: Received: 03 Sep 2025 — Revised: 06 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
WEPCO27
MEASUREMENT OF CRABBING ANGLE WITH PHASE INFORMATION FROM BPM
684
The Electron-Ion Collider is being constructed at the Brookhaven National Laboratory. The crab cavities will be utilized for the increase of the luminosity. While the initial set-up of crab cavities can be based on the orbit measurements during dedicated development time, we need to utilize a less invasive approach for monitoring the longitudinal beam tilt during operations. We propose to measure a phase shift between two beam position monitor channels for this purpose. The signal can be easily incorporated into the RF system feedback to suppress noise in the system. Theoretical considerations as well as tests with the electron beams are presented.
Paper: WEPCO27
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO27
About: Received: 14 Aug 2025 — Revised: 07 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPCO28
Measurement of two beams positions with button BPM
687
Modern BPM processors utilize digital processing of the beam induced signals. The information on the signal amplitudes is used for the delta over sum calculation of the beam position, while the readily available phase information is usually discarded. We have experimentally tested measurement of the individual positions of two beams propagating in the common beampipe utilizing both phase and amplitude data. The proposed method can be used for the energy recovery linacs and colliders.
Paper: WEPCO28
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO28
About: Received: 14 Aug 2025 — Revised: 07 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPCO29
Development of analog front-end module for the BPM signal processor at SSRF
690
A new BPM processor is being developed to address the ageing of BPM signal processors and the new demand for synchronised data acquisition at the storage ring of Shanghai Synchrotron Radiation Facility (SSRF). The BPM processor consists primarily of a digital carrier board and an analog front-end (AFE) module. The AFE is responsible for the conditioning of the BPM output RF signal and for the compensation of long-term drift. This paper presents the design of the AFE module and gives an evaluation of its performance. The experimental results show that the AFE module under development fully satisfies the high resolution and high stability requirements of the upgraded SSRF BPM processor.
Paper: WEPCO29
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO29
About: Received: 03 Sep 2025 — Revised: 08 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPCO31
Development and evaluation of an RFSoC based stripline BPM readout hardware prototype
693
We have developed a Stripline BPM readout device based on an AMD/Xilinx RFSoC chip which integrates multiple ADCs, DACs, a large scale FPGA, and an ARM processor in a single package. The developed device is intended for use at the beam transfer line connecting the KEK injector Linac to the SuperKEKB collider rings. SuperKEKB will operate at unprecedented luminosities requiring very high beam currents. To reach and maintain such currents, high injection efficiency is essential which in turn requires precise tuning of the injection process. The RFSoC based BPM will provide a highly flexible platform for beam orbit measurements near the injection point required for the tuning. One objective is to enable the separate resolution of the orbit of both bunches in the two-bunch injection mode, where two bunches are accelerated and injected with 96 ns spacing. Additionally, we plan to utilize resulting measurements as inputs for real-time automated injection tuning and feedback to the upstream steering in the beam transport line. Here, we present the status of the development including results from prototype tests conducted at the KEK injector Linac.
Paper: WEPCO31
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO31
About: Received: 27 Aug 2025 — Revised: 05 Sep 2025 — Accepted: 08 Sep 2025 — Issue date: 20 Jan 2026
WEPCO32
Upgrade of beam position diagnostics System at FELiChEM
697
The FELiChEM is a user facility dedicated for energy chemistry research, developed at University of Science and Technology of China in Hefei. The beam position diagnostics system at FELiChEM are upgraded recently. The facility operates with a special mode: macropulses at 1 Hz repetition rate with microsecond duration, each containing micropluses at 59.5 MHz repetition rate. The key advancement of beam position monitor (BPM) system lies in the upgraded which now achieves micropluse-level resolution. This enhancement enables real-time measurement of transverse position deviations for individual micropluses, providing essential diagnostics for investigating intra-macropulse instabilities. Post-upgrade characterization demonstrates a transverse position resolution better than 20 μm, satisfying design specifications. The upgraded BPM system has been successfully integrated into routine beam tuning operations.
Paper: WEPCO32
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO32
About: Received: 02 Sep 2025 — Revised: 07 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
Accurate offline calibration and simulation analysis of various types of BPM position sensitivity
Beam Position Monitors (BPMs) are the most commonly used non-destructive diagnostics for almost all linear accelerators, cyclotrons, and synchrotrons. It is very important for BPM to provide accurate beam position for closed-orbit correction, and etc. Meanwhile, it is necessary to accurately offline calibrate the BPM position sensitivity and evaluate whether the result is correct or not. In this paper, a method based on the principle of microwave multi-port network in the field of electromagnetic field is proposed to efficiently simulate the BPM position sensitivity; a large number of various BPMs (capacitive , linear-cut and stripline type) for HIAF and PREF projects were calibrated; comparing the calibration and simulated position coefficients, combined with the three-dimensional field distribution analysis, an in-depth and systematic study was carried out on various types of BPM calibration, during which some key points that determine whether the calibration results were accurate after the BPM was launched were found.
Bead Test Result of Cavity Beam Position Monitor for PAL-XFEL
A bead test was conducted to measure the shunt impedance (R/Q) of the cavity beam position monitor (BPM) for PAL-XFEL. R/Q is an important parameter of a cavity BPM because it relates to the signal strength, which determines the resolution of the beam position measurement. In the bead test, a dielectric and metal bead were used to assess the frequency change at various bead positions. The measurement results of the two beads from the monopole cavity were similar, but the results from the dipole cavity differed significantly. This discrepancy can be explained by considering the distribution of the electric and magnetic fields in the cavity structure and the materials of the two beads.
WEPCO37
Study of beam position monitors for PERLE
700
PERLE is an Energy-Recovery Linac (ERL) to be constructed at IJCLab in Orsay. It will be the First multi-turn ERL with superconducting RF (SRF) with the ambition to reach 10MW beam operation (20mA beam current and 500MeV beam energy) Diagnostics are a key element for PERLE operation and among diagnostics, the salient feature for Beam position monitors (BPMs) is the presence of multiple beams which need to be individually diagnosed and controlled. This document describes the design and the operation of PERLE BPMs with particular attention given to how these BPMs will handle multiple beams during commissioning and under normal operation of PERLE
Paper: WEPCO37
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO37
About: Received: 28 Aug 2025 — Revised: 07 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
WEPCO39
Development of bunch selector modules for double bunch operation in PAL-XFEL BPM systems
704
PAL-XFEL plans to begin double-bunch operation in 2027, with two electron bunches separated by 25 ns. The existing beam position monitor (BPM) electronics were designed for single-bunch operation, so the two signals overlap and bias the position measurement. To support this mode without modifying the electronics, we developed an external radio-frequency (RF) switch-based bunch selector that routes only the selected bunch to the BPM input. We built a prototype and conducted laboratory and on-site tests. This paper presents the hardware and experimental results.
Paper: WEPCO39
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPCO39
About: Received: 02 Sep 2025 — Revised: 05 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPMO04
Diamond dosimeter for the measurement of the proton beam impact position on a neutron spallation target
718
In close proximity to the spallation neutron source of the neutron time-of-flight facility n_TOF at CERN, diamond detectors are installed to measure the fast neutron beam. The detectors are located 2.3 m from the center of the spallation target at 100° with respect to the impinging proton beam. The 20 GeV/c proton beam from CERNs Proton Synchrotron (PS) hits the Pb-spallation target with a nominal intensity of 8.5e12 protons/bunch, a proton bunch length of 16 ns FWHM and a maximum repetition rate of 0.8 Hz. The proton beam intensity is monitored with a beam current transformer (BCT) installed in the PS extraction line to n_TOF. The proton beam position is measured using a SEM grid 2 m before the spallation target. A linear correlation between the horizontal proton beam impact position on the Pb-target and the measured dose of the secondary radiation at the measurement station for each pulse is observed. While the proton beam impact position varies by 12 mm, the normalised dose varies by 20%. The achievable precision of the proton beam position measurement using the diamond dosimeter and the linearity of the dose measurement for individual bunches is studied and will be presented.
Paper: WEPMO04
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO04
About: Received: 02 Sep 2025 — Revised: 11 Sep 2025 — Accepted: 25 Sep 2025 — Issue date: 20 Jan 2026
WEPMO05
Testing of SiC Blade X-ray Beam Position Monitors for Synchrotron Front-Ends
722
X-ray beam position monitors (XBPMs) play a crucial role in accurately measuring the position of the white beam in synchrotron front ends. Traditional XBPM designs typically feature four tungsten blades arranged at the full width at half maximum (FWHM) of the white beam. However, the high absorption and lower thermal resistance of tungsten limit the proximity of the blades to the X-ray source, which may negatively impact measurement precision. This study investigates the performance of an innovative XBPM design that utilises silicon carbide (SiC) blades, which provide enhanced thermal conductivity and reduced absorption. This advancement may allow for closer placement of the blades to the beam, potentially improving measurement accuracy. This experimental setup aims to assess the impact of SiC blades on measurement accuracy, signal-to-noise ratio, and linearity compared to conventional tungsten XBPMs. The results will offer valuable insights into the benefits and limitations of SiC-based XBPMs compared to their tungsten counterparts.
Paper: WEPMO05
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO05
About: Received: 03 Sep 2025 — Revised: 06 Sep 2025 — Accepted: 08 Sep 2025 — Issue date: 20 Jan 2026
WEPMO06
Geometrical studies for the arc beam position monitors FCC-ee
726
The electron-positron Future Circular Collider (FCC-ee) has challenging requirements for beam instrumentation, including the need for thousands of high-resolution beam position monitors (BPMs) presenting low impedance to the circulating beam. This paper details the requirements for the FCC-ee arc BPMs and investigates button-type pickups with various geometries through electromagnetic simulations using FCC-ee design parameters. The simulation results are used to estimate key BPM characteristics, including impedance and heating.
Paper: WEPMO06
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO06
About: Received: 03 Sep 2025 — Revised: 09 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPMO07
Gain calibration for eliminating X-Y coupling in X-ray beam position monitors at SPring-8 photon beamlines
729
Although synchrotron radiation originates from charged particle beams, monitoring its positional stability requires distinct technical approaches. To enhance the accuracy of position and angle measurements of the synchrotron radiation beam at SPring-8 BL15XU, both a quadrant-type XBPM and a fixed-blade XBPM were installed on the same beamline. In the quadrant-type XBPM, widening the detector spacing led to noticeable X-Y coupling. To address this, a 2×2 correction matrix was introduced to perform linear transformation of the measured signals. The proposed method successfully eliminated X-Y coupling while maintaining resolution, enabling simultaneous operation of both XBPMs.
Paper: WEPMO07
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO07
About: Received: 03 Sep 2025 — Revised: 08 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
WEPMO08
Development of BPM electronics for TRIUMF’s BL4N
733
The BL4N beamline at TRIUMF, currently under development, will transport proton beam from the 500 MeV cyclotron to an ISOL target station. The peak beam current will be varied from 1 to 100 microamps, and the beam position must be measured over a 10mm range. The beam position is measured using inductive pick-ups and a new narrowband frontend. The electronics consist of a crossbar-switched front-end, FPGA-based down-conversion and position calculation, and an SoC module for nonlinear corrections and device readout. This report presents the design and testing of the BPM electronics, including benchtop validation and beam test results. Measurements of position sensitivity, beam current dependence, and non-linearity are included.
Paper: WEPMO08
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO08
About: Received: 02 Sep 2025 — Revised: 05 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
WEPMO09
Online position conversion factor calibration study for BPM system
736
Transverse beam position is one of the most critical parameters in accelerator commission and operation. As non-invasive diagnostic devices, beam position monitors (BPMs) are the main “workhorse” in accelerators, providing beam center of mass position information. The position conversion factor (K-factor) of BPM systems constitutes a fundamental determinate of measurement accuracy. While precision calibration traditionally relies on moveable calibrate platforms, the prohibitive cost of equipping each BPM with a dedicated two-dimensional calibration platform remains a widespread practical constraint. In this paper, an innovative online calibration method that synergizes machine learning with beam response matrix analysis to achieve per-BPM K-factor determination is introduced. The preliminary beam experiments have been carried out at Shanghai Soft X-ray Free-Electron Laser (SXFEL) facility. The proposed method offers a robust and resource-efficient calibration solution, particularly advantageous for cavity BPM systems where conventional approaches such as theoretical calculation and offline wire scanning, fail to provide reliable results.
Paper: WEPMO09
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO09
About: Received: 03 Sep 2025 — Revised: 10 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
Performance evaluation of front-end attenuators and integrated gain calibration system for new BPM DAQ system at J-PARC MR
The J-PARC MR achieved its initial target of 750 kW operation and is currently upgrading its equipment to reach the next target of 1.3 MW. The Beam Position Monitor (BPM) must enhance position accuracy to less than one-third of that of the current system to mitigate beam losses caused by accelerating the high-intensity proton beam of 3.3E14ppp. To address this, a new Data Acquisition System (DAQ), comprising Front-end Attenuator Boards (ATT), ADC Boards, Network Interface Controllers, and a Data Storage System, is under development. Improving position accuracy relies on improving reflection at the ATT's input terminal and adjusting the gain balance for each signal channel. A self-contained gain tuning system using a self-generating test pulse and an input impedance tuning circuit has been adopted to mitigate the reflection at the ATT and enhance the gain balance across all components, including sensors, signal transmission cables (100–300m), and the DAQ. The installation of the DAQ system is for this winter and the ATT calibration and performance testing are currently underway. This report presents the calibration results and their impact on beam position accuracy.
WEPMO11
Design and expected performance of the new BPM systems for AWAKE Run 2C
739
The AWAKE facility at CERN uses novel proton beam-driven plasma wakefields to accelerate electron bunches over a 10 m plasma source. The facility will soon be rebuilt to study methods to improve the quality of the accelerated electron beam, requiring better resolution from the proton BPMs. In addition, it is desirable to replace the existing bespoke electron BPMs with an in-house solution. Both upgrades will reuse the existing BPM pickups (electrostatic buttons and striplines, respectively) but replace the electronic front-ends and control system interfaces. An RFSoC-based BPM front-end is concurrently being developed for the HL-LHC upgrade, which, if appropriate for AWAKE, would reduce production and maintenance efforts. For the proton BPMs, distributed along an 800 m transfer line, time-multiplexing of both pickups per plane has been chosen both to reduce cabling and channel count and improve systematic errors in the measurements. We present the expected performance of both the AWAKE proton and electron BPMs using the prototype HL-LHC BPM front-end, based on measurements from the existing facility.
Paper: WEPMO11
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO11
About: Received: 02 Sep 2025 — Revised: 05 Sep 2025 — Accepted: 11 Sep 2025 — Issue date: 20 Jan 2026
WEPMO12
Digital signal processing improvements of the SPIRAL2 beam position monitors at low intensity
743
The SPIRAL2 accelerator, designed for high intensity beams (up to 5 mA), needs to evolve for low intensities in order to reach the requirements of the S3 experimental room. This means increasing the operating range of diagnostic monitors including the Beam Position Monitors (BPM). Twenty BPM are installed in the warm sections of the linac to measure positions, ellipticities and phases. The digital processing of the BPM acquisition has been modified to operate at low intensity. This was done by improving the signal-to-noise ratio with an increase of the averaging resolution, an improvement of the channel equalisation system and with a deduction of parasitic signals induced by the surrounding equipment. The process was also modified to operate with chopper frequencies between 1 Hz and 1 kHz. A new BPM interface, with tables and graphical displays in order to control beam phases and energies in the linac, is now available. These new developments and measurement results in laboratory and with SPIRAL2 beams are presented, which show good results with a low intensity down to 1 µA.
Paper: WEPMO12
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO12
About: Received: 29 Aug 2025 — Revised: 05 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPMO17
New photon BPM setup using SiC devices in photoconductive mode
755
Photon Beam Position Monitors (pBPM) detect photon beam intensity and position in synchrotron light sources and are capable to operate in real time during experiments, without altering beam properties and ideally discriminating between insertion device (ID) and bending magnet (BM) radiation. Early approaches used metallic blades based on photoemission from beam tails, but failed with micrometric beams or too high energy photons. They were also unable to distinguish between BM and ID radiation. Newer techniques based on CVD diamond detectors, using charge collection in four quadrants, work well at high energies but absorb too much at soft X-rays or lower energies. Thinning sensors down to the nanometer scale is technically challenging and does not solve the problem of light source discrimination. We propose an innovative method using intrinsic silicon carbide (SiC) sensors, not as a replacement for blades, but as a matrix of photoconductive elements, positioned directly after the synchrotron source, each capable of separately detecting BM and ID radiation. Initial tests show sub-micron sensitivity and clear separation of beam contributions, offering a new way forward.
Paper: WEPMO17
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO17
About: Received: 02 Sep 2025 — Revised: 07 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
WEPMO18
Beam measurement during swap-out injection of the APS-U storage ring
759
The Advanced Photon Source Upgrade (APS-U) implements a novel swap-out injection scheme. To comprehensively characterize the beam dynamics during swap-out injections, approximately 20 Beam Position Monitors (BPMs) in the initial sections of the storage ring have been equipped with high-precision single-bunch electronics. These systems are capable of measuring the turn-by-turn positions of the injecting bunch. Using similar techniques, the longitudinal phase and energy of the injecting bunch can be accurately assessed. Additionally, bunch-by-bunch feedback systems have been used to measure transient beam motions, extending their primary functionality of suppressing coupled bunch instabilities. This paper presents the results of beam measurements during swap-out injections utilizing these advanced systems.
Paper: WEPMO18
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO18
About: Received: 02 Sep 2025 — Revised: 08 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
WEPMO19
Longitudinal profile measurements of particle beams with deconvolution in the APS-U Storage-ring
763
Accurate measurement of the longitudinal profile, or bunch length, of particle beams is essential for evaluating and optimizing beam quality in the Advanced Photon Source Upgrade (APS-U) Storage Ring. While Beam Position Monitor (BPM) signals are typically used for precise position measurements, they also contain information about the longitudinal bunch distribution, convolved with the BPM system’s transfer function. To extract the true bunch profile, CST Studio is used to simulate the BPM response to a short Gaussian pulse—approximating a Dirac delta function—thereby providing the BPM’s transfer function. The transfer functions of signal cables and attenuators are also measured and combined with the simulated BPM response to construct a complete system transfer function. This composite response serves as the deconvolution kernel for reconstructing the original time-domain bunch profile from the measured BPM signals. BPM signals from the APS-U’s tuned Bunch Lengthening System (BLS) are analyzed in both time and frequency domains. Deconvolution with the simulated transfer function yields accurate longitudinal profiles and enables precise extraction of bunch lengths.
Paper: WEPMO19
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO19
About: Received: 02 Sep 2025 — Revised: 09 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
WEPMO20
Study of a novel eight electrodes RF pickup
766
The IFMIF-DONES facility located at Escúzar in Spain will consist of an accelerator delivering 125 mA of 40 MeV deuterons onto a Lithium target. At the last part of the accelerator, when the beam footprint is almost shaped, different beam diagnostics are considered. In order to protect the machine against changes of the beam and give a safe interlock, a novel RF pickup made of eight electrodes is designed. This RF pickup is designed with the objective to sense displacements of the beam centroid as changes of the beam profile. In this paper a preliminary study is presented based on an analytical and CST simulation approach. Both approaches, considering pencil and real beams from TraceWin simulations, are compared. Next, a sensitivity study of how different parameters affect the response is performed in CST simulations. This work has been carried out within the framework of the EUROfusion Consortium.
Paper: WEPMO20
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO20
About: Received: 01 Sep 2025 — Revised: 08 Sep 2025 — Accepted: 08 Sep 2025 — Issue date: 20 Jan 2026
WEPMO21
Status of the EIC HSR cold beam position monitors mechanical design and integration
770
The Electron Ion Collider (EIC) Hadron Storage Ring (HSR) aims to leverage the hardware from the RHIC storage ring as much as possible. However, the RHIC stripline beam position monitors (BPM) used in the superconducting magnet cryostat will not be compatible with the planned EIC hadron beam parameters that include shorter bunches, higher beam current and operation of the beam with a radial offset in the vacuum chamber. A new cryogenic BPM design using button pick-ups integrated in a new interconnect bellow assembly will be installed adjacent to the decommissioned RHIC stripline BPMs. This paper will review some of the design considerations of the BPM system ahead of their procurement.
Paper: WEPMO21
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO21
About: Received: 02 Sep 2025 — Revised: 08 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
WEPMO22
Button-type beam position monitors for Elettra 2.0: from design to real measurements
774
This paper describes the main stages of the journey from preliminary ideas on button shapes to actual measurements on prototypes of Beam Position Monitor (BPM) devices for Elettra 2.0. In the first stage, the electromagnetic phenomena involved in BPM sensors were studied taking into account different pick-up geometries, dielectric and conductive materials, and bunch lengths. Critical aspects such as beam coupling impedance, transfer impedance, impedance matching, trapped/propagating mode effects and heating were evaluated through numerical simulations. In the second stage, three families of vacuum-tight pick-up samples were fabricated in-house, and their actual performance was evaluated both on a microwave test bench and in real operating conditions on the Elettra storage ring. To carry out future measurements on alternative BPM designs, the third family was specifically conceived and built to allow quick and easy pick-up replacement using ultra-high vacuum shape memory alloy sealing technology. The third stage focused on comparing the signals produced by the Elettra BPMs with those foreseen for Elettra 2.0, and also allowed validation of the in-house developed BPM electronics.
Paper: WEPMO22
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO22
About: Received: 03 Sep 2025 — Revised: 04 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPMO23
Performance results of novel photoemission mask X-ray beam position monitor for ‘white’ undulator radiation
778
A prototype of a novel Photoemission Mask type X-ray Beam Position Monitor (PheM XBPM) for the ‘white’ undulator radiation which concept was proposed in Ref. [1] has been built and tested. The prototype was designed and manufactured at MAX IV. Two PheM XBPMs were installed at MAX IV 3 GeV storage ring at SoftiMAX and CoSAXS beamline frontends. Signal modelling, optimization and performance results of the PheM XBPM are discussed. [1]. https://accelconf.web.cern.ch/ibic2022/papers/mop44.pdf
Paper: WEPMO23
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO23
About: Received: 02 Sep 2025 — Revised: 09 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPMO24
OPTIMIZATION OF PHOTOEMISSION BLADE X-RAY BEAM POSITION MONITOR FOR WIDE RANGE OF UNDULATOR GAP OPERATION
781
Optimization of the photoemission blade type XBPM mostly performed to increase its resolution by increasing the readout signal current and by optimizing blades geometry. This requires tailoring of the XBPM for a particular undulator, making almost every XBPM unique at the Synchrotron Radiation facility. In many cases the calibration coefficient is gap dependent. To overcome those drawbacks an alternative optimization strategy is considered which will help to minimize gap dependence and could provide a unified XBPM design for all XBPM at Synchrotron Radiation (SR) facility.
Paper: WEPMO24
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO24
About: Received: 02 Sep 2025 — Revised: 15 Sep 2025 — Accepted: 25 Sep 2025 — Issue date: 20 Jan 2026
WEPMO25
Suitability of GHz frequency beam position monitors for electron bunch position discrimination in the AWAKE facility
784
The AWAKE facility at CERN utilises proton beam-driven plasma wakefields to accelerate electron bunches in a 10-meter long rubidium plasma cell. Precise monitoring of the electron bunches in the presence of the more intense proton bunches, which have distinct temporal and spatial characteristics, requires a beam position monitor (BPM) operating in the tens of GHz frequency range, assuming Gaussian longitudinal particle distributions. Two types of BPMs, one based on Cherenkov diffraction radiation (ChDR), and the other utilising high frequency (HF) conical shaped pickups, have been explored as a method to distinguish the electromagnetic signals of the shorter electron bunches (a few ps) from those of the longer proton bunches (a couple of hundred ps) co-propagating in the AWAKE beamline. Recent tests of both BPMs in the AWAKE common beamline have been conducted across frequencies in the range 20 – 110 GHz. The sensitivity of the HF and ChDR BPMs to the electron beam position was determined under various beam conditions, with and without proton bunches present. The read-out, utilising a RF front-end developed by TRIUMF, is additionally discussed.
Paper: WEPMO25
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO25
About: Received: 03 Sep 2025 — Revised: 07 Sep 2025 — Accepted: 11 Sep 2025 — Issue date: 20 Jan 2026
WEPMO26
Investigation of readout methods for electro-optical beam position monitor pickups
788
Electro-optical pickups are being explored at CERN for the development of a high-bandwidth beam position monitor capable of measuring intrabunch beam position. To support this effort, a prototype electro-optical beam position monitor has been installed in the SPS. The installation utilises a fibre-coupled laser directed into lithium niobate crystals. As the beam passes a crystal, its electromagnetic field induces a proportional phase shift in the laser light by altering the crystal’s refractive index. Signal readout is typically performed using a Mach-Zehnder interferometric setup, with crystals placed on either side of the beam. This configuration currently faces challenges including imperfect pickup matching, baseline instability, and limited dynamic range. This paper examines and evaluates various methods and techniques for reading out the beam position from the phase-shifted laser to mitigate these limitations.
Paper: WEPMO26
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO26
About: Received: 02 Sep 2025 — Revised: 09 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPMO30
Design study of the beam position monitor for the Hadron Center at Kutaisi International University
803
Cyclotron-based proton beams are widely used in research and medical applications due to their capability to deliver bunched beams across a broad range of bunch charges. One of the most critical components in beam diagnostics is the beam position monitor (BPM), which must accurately measure the beam’s position while minimizing disturbance to the beam. At Kutaisi International University (KIU), a superconducting synchro-cyclotron (S2C2) provided by Ion Beam Applications (IBA) will be dedicated exclusively to research, supporting diverse experiments that benefit from proton bunched beams of different intensities. To accommodate these experiments, construction of compact beamline is planned. In this work, we present the electromagnetic design study of an electrostatic BPM that can operate effectively address to the physical and operational constraints of the new beamline.
Paper: WEPMO30
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO30
About: Received: 29 Aug 2025 — Revised: 09 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPMO31
Noninterceptive beam energy measurement of high-frequency free electron lasers
806
Free electron lasers (FEL), which can generate ultra-high brightness rediation are working horses for radiation science research over the world. For FEL, the higher the repetition frequency of the beam in the device, the higher the user's experimental efficiency, and more experimental stations can conduct experiments simultaneously. Therefore, there is a trend to increase the repetition frequency in its development process. Therefore, it is necessary to develop relevant technologies for high repetition frequency FEL. Beam energy is one of the most fundamental and critical parameters in FEL. This paper developed a fusion algorithm based on beam position monitor (BPM) in the dispersion structure of a FEL, which extracts the transverse position of the beam using both the arrival time and amplitude information of the beam, to achieve high-precision and noninterceptive measurement of beam energy. Provide powerful diagnostic, operational, and maintenance tools for high-frequency free electron laser devices.
Paper: WEPMO31
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO31
About: Received: 02 Sep 2025 — Revised: 09 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
WEPMO32
Beam Position Monitoring and Polarimetry with a Timepix3 Pixel Detector at a Compton Backscattering Polarimeter
810
The ELSA facility at the University of Bonn uses a storage ring to accelerate polarized electrons up to 3.2 GeV. To monitor the polarization degree of the stored beam a Compton polarimeter is used to analyze the profile of the backscattered beam of gamma rays. In addition to a silicon microstrip detector with vertical resolution, a Timepix3 pixel detector is tested as alternative detector for the usage in beam polarimetry and beam position monitoring. The current status of the alternative detector setup is presented.
Paper: WEPMO32
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO32
About: Received: 03 Sep 2025 — Revised: 10 Sep 2025 — Accepted: 11 Sep 2025 — Issue date: 20 Jan 2026
Novel high-current multichannel ammeter for X-ray Beam Position Monitoring (XBPM) applications
This work presents the development and characterization of PCR4, a novel pico-to-milli ammeter jointly developed by STLab srl and SenSiC GmbH, specifically designed for applications requiring high-current readout, allowing for monochromatic and polychromatic beams measurement. PCR4 features four independent channels, each with 24-bit resolution, a 10 kHz sampling rate, and an ultra-wide dynamic range spanning 9 decades—from 1 pA to 50 mA. The system is optimized for non-destructive white-beam X-ray detection and incorporates an integrated bipolar voltage bias source (-20 V to +20V), facilitating the commissioning of Silicon Carbide (SiC) sensors and allowing pre-installation dark current measurements. A detailed metrological characterization will be presented, including spectral noise density, linearity, dynamic range, signal-to-noise ratio (SNR), and long-term stability across varying input capacitances. Additionally, the integration of feedback control loops into the system and strategies for further bandwidth extension will be discussed, with the aim of supporting low-latency orbit feedback systems operating at 10 kHz.
High-Frequency Beam Position Monitoring: A 500 MHz BPM System by Safran
Beam Position Monitors (BPMs) are essential diagnostic tools in any particle accelerator, as they provide accurate measurements of the beam's position, phase, and intensity along the accelerator line. Safran Electronics & Defense, Spain is responsible for the complete design, implementation, production, and validation of a BPM electronic system tailored to project-specific requirements. Operating at a frequency of 500 MHz, the system has undergone initial testing at Safran’s facilities, yielding promising preliminary results. This paper presents the overall system architecture, the design and development process, and an overview of the system’s performance. It also highlights the advantages of the chosen architecture and summarizes the results obtained under various testing scenarios.
WEPMO40
Optimization and upgrade of the BPM electronics system for CSNS-II RCS
829
As the China Spallation Neutron Source (CSNS) Phase II project increases the Rapid Cycling Synchrotron (RCS) power to 500 kW, the signal intensity of Beam Position Monitors (BPMs) is expected to rise tenfold, necessitating a comprehensive upgrade of the electronics system to meet high-power operational requirements. Drawing on the experience of the J-PARC Main Ring (MR) 1.3 MW power upgrade, CSNS optimized the analog front-end using a MicroTCA-based RTM board. The initial four-stage passive resistive divider was upgraded to a switchable attenuator combined with proportional voltage division, alongside impedance matching techniques, ensuring stable signal attenuation under high input voltages, minimal reflections, and compatibility with the Analog-to-Digital Converter (ADC) dynamic range. The digital processing is implemented on a self-developed MicroTCA.4-based AMC board, utilizing the Xilinx Zynq-7045 SoC with 8 channels of 16-bit ADC (125 MSPS). The system has successfully transplanted algorithms, supports real-time beam position calculations, and publishes position signals via EPICS. Tests demonstrate low noise, high linearity, and performance.
Paper: WEPMO40
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO40
About: Received: 03 Sep 2025 — Revised: 10 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026