WEPMO
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Wednesday Poster Session
10 Sep 2025, 16:00 -
18:00
WEPMO02
Preparing the next phase of the steady-state microbunching proof-of-principle experiment at the Metrology Light Source
711
Steady-state microbunching (SSMB) is a proposed scheme to generate coherent radiation at short wavelengths from a microbunched electron beam in a storage ring. The feasibility of the idea is investigated in an ongoing proof-of-principle (PoP) experiment conducted at the Metrology Light Source (MLS). Phase I of the SSMB PoP experiment has been using an experimental setup employing a single-shot modulation laser to show the general viability of the idea, and has explored the underlying complex storage ring dynamics. The next step in the SSMB PoP campaign is to progress from the single-shot setup of phase I towards quasi-steady state. To this end, a new laser system is installed at the MLS that can provide turn-by-turn modulation of the electron beam for 1000 revolutions. The main goal of this phase II of the SSMB PoP experiment will be to show bound motion of electrons within individual laser-induced microbunches. In this paper, we show the progress of preparation for PoP phase II, with emphasis on the setup and integration of the new laser system and diagnostics challenges.
Paper: WEPMO02
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO02
About: Received: 25 Aug 2025 — Revised: 11 Sep 2025 — Accepted: 11 Sep 2025 — Issue date: 20 Jan 2026
WEPMO03
Smith-Purcell and transition radiation based charged particle beam diagnostics for the femtosecond-range
715
We will give an overview of the Smith-Purcell and transition radiation based longitudinal diagnostic methods employed at the ARES (Accelerator Research Experiment at SINBAD) linear accelerator to characterize femto-second long electron bunches. The Smith-Purcell radiation mechanism has been studied for the case of metallic gratings, but not much experimental data has been published yet with respect to dielectric gratings as charged particle beam diagnostic devices. We expect a number of advantages in the detection of the radiation at the substrate side and the spectral properties of the radiation tailored by the geometric shape of the grating structures. Due to the advances in lithographic techniques dielectric gratings can be produced with optical wavelength periodicities and the shapes can be controlled with nano-meter precision. For femto-second bunch lengths the coherence of transition radiation starts to reach the near-infrared to optical regime. This opens up the possibility of characterizing the spectrum with readily available high sensitivity semi-conductor based detectors to draw conclusions on the form factor and measure bunch lengths.
Paper: WEPMO03
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO03
About: Received: 06 Sep 2025 — Revised: 17 Sep 2025 — Accepted: 17 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
WEPMO13
Single-shot detection of short electron bunch shapes at MHz repetition rates using diversity electro-optic scheme with advanced reconstruction algorithms at EuXFEL and FLASH
746
To surpass limitations in sub-picosecond electro-optic electron bunch length diagnostics[1], we present an innovative detection method utilizing diversity schemes[2]. This approach employs simultaneous multi-output measurements of the chirped optical probe modulated by the electron bunch's field. We introduce a novel inversion algorithm that automatically recognizes and compensates for imperfections in the probe laser spectrum and chirp, enabling high-fidelity retrieval of bunch shapes, particularly for broadband THz radiation over a long temporal window. Numerical simulations and initial experimental results demonstrate the system's potential for advanced, real-time bunch shape monitors at FLASH and EuXFEL, and can be extended to THz CTR or FEL based THz sources. [1] F. Sun, Z. Jiang, and X.-C. Zhang, Appl. Phys. Lett. 3, 2233 (1998) [2] E. Roussel et al., Light: Science & Applications 11, 14 (2022)
Paper: WEPMO13
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO13
About: Received: 03 Sep 2025 — Revised: 08 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
Development of Pyroelectric Detectors for THz Diagnostics on CLARA
CLARA is a high-brightness 250 MeV electron test facility, which aims to deliver high quality beams to a flexible user area called FEBE, supporting experiments in areas such as novel acceleration. * The requirements of these experiments impose stringent diagnostic requirements. This paper will describe progress on the pyroelectric detectors intended for use with a multi-channel THz spectrometer**, including their design and offline tests with a THz source, as well as future plans for integrating them with the spectrometer design.
WEPMO15
Timing system at the Canadian Light Source
749
The Canadian Light Source (CLS) is a third generation 2.9 GeV synchrotron comprised of a 250 MeV LINAC, a full energy booster, and a storage ring with 13 insertion devices and 22 operational beamlines ranging from infrared light to hard X-rays. The Timing System supplies the triggers required to synchronize operation of all components responsible for injecting current into the storage ring. Signals from the Timing System can also be used to synchronize data acquisition on beamlines. The Trigger Generator Unit (TGU), which was designed by the CLS, is the centerpiece of the timing electronics. The TGU is driven by the 500 MHz master oscillator and is controlled using digital I/O. The trigger signals are distributed via a fiber optic system, which was also designed in house. The Timing System has been in operation since 2001 and has proven itself to be stable and robust. This paper provides a detailed overview of the system and its history and operational performance.
Paper: WEPMO15
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO15
About: Received: 03 Sep 2025 — Revised: 04 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPMO16
A compact device for measuring and monitoring the energy of accelerated particle beams
752
A Beam Energy Monitor (BEM) was developed for the cyclotron of the HUN-REN ATOMKI, using TOF measurements on a short flight path. The sensor unit uses two capacitive probes at a distance of 20 cm, the entire geometry is about 40 cm long. The compact size allowed the unit to be installed in the main beamline, making it possible to measure and monitor the beam energy independently of the beamline actually used. The probe signals are acquired by a digital oscilloscope and the time difference between the pulses generated by a beam bunch on the probes is determined by digital signal processing algorithms. The unique design* of the sensor unit and the signal processing hardware and software combine to provide accurate beam energy measurement despite the short flight path. Accuracy in practical operation was investigated by neutron threshold reactons. They showed that the measurement accuracy is at least one order of magnitude better than the accuracy of the energy value calculated from the cyclotron settings. The accuracy of the signal processing shows that the beam energy can be scaled up to several hundred MeV while maintaining the measurement accuracy at the tenth of a percent level.
Paper: WEPMO16
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO16
About: Received: 07 Aug 2025 — Revised: 07 Sep 2025 — Accepted: 08 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
WEPMO27
Transverse and longitudinal beam diagnostics and characterizations at IUAC-high current injector
792
The High Current Injector features normal-conducting RF Linac structures intended to accelerate various ion species with a mass-to-charge ratio of up to 6, achieving a maximum output energy of 1.8 MeV/u. It can deliver an intense analyzed beam up to 100pnA at the target. To preserve the beam quality at the target and to improve the performance of RF cavities and beam transmission, both destructive and non-destructive, fast and precise transverse and longitudinal beam diagnostics (including FFCs and CPOs for phase space and ToF measurements) are deployed in LEBT, MEBT and HEBT section of HCI. The beam energy was validated through the existing Surface Barrier Detector measurement setup. Recently, during 20Ne9+ beam test, we observed a notable energy spread of approximately 1%, which led to pronounced debunching and a complete loss of the necessary signal component in the downstream BPMs. To mitigate the energy spread, slits have been installed at the image plane of the fourth achromatic bending magnets, and it was observed that optimally adjusting the slits can reduce the spread by over fifty percent. This paper will present the latest measurements, challenges and future plans.
Paper: WEPMO27
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO27
About: Received: 03 Sep 2025 — Revised: 08 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
WEPMO28
Optimisation of a fibre-based two-colour balanced optical cross-correlator
795
As part of the ongoing Full Energy Beam Exploitation (FEBE) upgrade to the Compact Linear Accelerator for Research and Applications (CLARA) at the Daresbury Laboratory, UK, few-femtosecond optical synchronisation between the new Ti:Sapphire terawatt FEBE laser and the Er:Yb optical master oscillator (OMO) is required for user experiments. To achieve this, a fibre-based two-colour balanced optical cross-correlator (BOXC) using waveguided periodically-poled lithium niobate (PPLN) crystals is being developed. A fibre-based BOXC could have greater sensitivity to timing jitter between two lasers than traditional free-space devices. In this manuscript, the design of the fibre-based two-colour BOXC is presented. The effect of pulse chirp on the sensitivity of the BOXC is investigated, and plans for optimising the design of the BOXC are discussed along with plans for integrating the fibre-based BOXC into the optical synchronisation network at Daresbury.
Paper: WEPMO28
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO28
About: Received: 03 Sep 2025 — Revised: 05 Sep 2025 — Accepted: 10 Sep 2025 — Issue date: 20 Jan 2026
WEPMO29
Application of phase detectors at the Taiwan Photon Source
799
A phase detection system has been implemented at the Taiwan Photon Source, employing beam position monitor (BPM) electronics integrated with a digital inphase/quadrature (I/Q) demodulation scheme. This system enables high-resolution analysis of beam phase stability, RF cavity field phase, and synchronization integrity of the RF clock distribution. It also facilitates the investigation of beam phase variations under dynamic operational conditions, including changes in insertion device gaps and booster ramping cycles. This paper presents the operational principles, implementation architecture, and representative experimental results of the developed detector system.
Paper: WEPMO29
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO29
About: Received: 28 Jul 2025 — Revised: 07 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
WEPMO33
Studies of longitudinal phase space tomography using booster cavity and dipole spectrometer
813
Information on the longitudinal phase space (LPS) is essential for tuning injectors that deliver a few-femtosecond electron bunches to beam–plasma interaction experiments and ultrafast diffraction facilities. Direct time–energy characterization, however, is challenging due to the limited resolution of conventional diagnostics. To address this, we apply a tomographic algorithm that uses a booster cavity and a downstream dipole spectrometer to indirectly reconstruct the LPS. A phase scan of the booster cavity adjusts the longitudinal chirp, while the dipole converts the correlated energy spread into a transverse distribution on a screen. An iterative algorithm then retrieves the time–energy distribution. Particle tracking simulations confirm that the method successfully reconstructs the LPS structure. Our next step is to verify the technique on the actual beamline, compare the LPS measured using an RF deflecting cavity with the reconstructed distribution, and use the results to guide injector tuning. We also discuss the potential application of the LPS tomography algorithm developed in this study to non-relativistic ion beams, using a re-bunching cavity and a bunch shape monitor.
Paper: WEPMO33
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO33
About: Received: 10 Sep 2025 — Revised: 11 Sep 2025 — Accepted: 25 Sep 2025 — Issue date: 20 Jan 2026
WEPMO34
Longitudinal bunch profile reconstruction via Cherenkov radiation in optical fibers
817
Optical beam diagnostics, such as OTR screens and streak cameras, can overcome bandwidth limitations of electronic diagnostics. However, efficient light collection and transport is challenging. At the PEER (Pulsed Energetic Electrons for Research) facility at the Australian Synchrotron (AS), we use Cherenkov radiation (CR) generated in optical fibers to reconstruct longitudinal bunch profiles at ps timescales, using a streak camera. This is enabled by proportionality of emitted CR intensity to incident charge*, when electrons directly impact the fiber. Streak cameras have been used to image CR**, but generating and transporting CR in the same fiber is novel, simplifying detector design and light transport. We present bunch profile measurements using this technique and assess its feasibility. We quantify distortion of CR due to modal and chromatic dispersion in the fiber, survey methods to reduce distortion, and improve signal-to-noise ratio. Bunch profile measurements at ps resolution may enable bunch purity optimisation and detection of microbunching, previously not possible at PEER. This will greatly benefit PEER users, as well as beam quality in the AS booster and storage rings.
Paper: WEPMO34
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO34
About: Received: 04 Sep 2025 — Revised: 05 Sep 2025 — Accepted: 09 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.
WEPMO36
Concepts for beam diagnostics based on planar pickups on a printed circuit board
821
For the upgrade of the electro-optical bunch arrival-time monitors (EO-BAMs) employed at several free-electron laser (FEL) facilities, a novel pickup structure has been proposed. Its feasibility was successfully tested at the ELBE accelerator. The design comprises planar pickups on a printed circuit board (PCB) with an integrated combination network. It delivers a significantly stronger signal compared to established pickups. Applying the upgrade to existing machines enables two key capabilities: Reliable operation at 1 pC charge levels for FELs and ultrafast electron diffraction facilities, and enhanced arrival-time resolution for standard operational modes. Furthermore, the PCB implementation enables unprecedented flexibility in planar pickup design, facilitating multi-functional diagnostic capabilities. This work presents a compact implementation strategy for integrating high- and low-resolution channels for EO-BAMs on a single substrate through a dual-functionality layout, and conceptual advancements in beam diagnostics using a PCB architecture for measuring other beam properties.
Paper: WEPMO36
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO36
About: Received: 03 Sep 2025 — Revised: 09 Sep 2025 — Accepted: 11 Sep 2025 — Issue date: 20 Jan 2026
WEPMO37
Preliminary radiation hardness characterization of ultra-broadband direct THz detectors based on Schottky diodes and GaAs TeraFETs
825
Many currently operating and future FELs can generate radiation at megahertz repetition rates, requiring an ultra-broadband, compact, robust & fast (response time at least on a single-digit nanosecond scale) diagnostic tool. We develop ultrafast-operating terahertz detectors based on Schottky diodes and GaAs field-effect transistors (TeraFETs) that operate at room temperature. Here, we present the preliminary radiation hardness characterization of these detectors. Promising results demonstrate the ability of these detectors to be commissioned at accelerator facilities for longitudinal beam diagnostics.
Paper: WEPMO37
DOI: reference for this paper: 10.18429/JACoW-IBIC2025-WEPMO37
About: Received: 03 Sep 2025 — Revised: 06 Sep 2025 — Accepted: 09 Sep 2025 — Issue date: 20 Jan 2026
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.
Machine learning based image processing technology for longitudinal phase space analysis in a compact THz-FEL
The longitudinal phase space characterization of electron bunches plays a crucial role in operational optimization of accelerator facilities. Currently, the terahertz free-electron laser (THz-FEL) facility at Huazhong University of Science and Technology (HUST) uses a combined deflecting cavity and dipole magnet system for longitudinal phase space measurements of bunches. In order to achieve non-intercepting measurements and also for automated parameter optimization, we developed an image-based virtual diagnostic system utilizing convolutional neural networks trained on simulated bunch data. Our preliminary results demonstrate successful longitudinal phase space reconstruction of the injector output bunch with prediction accuracy exceeding 85%.
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