02 Beam Position Monitors
Paper Title Page
MOP08 Development of a Waveguide BPM System 37
  • A. Lyapin, W. Shields
    JAI, Egham, Surrey, United Kingdom
  Funding: This work was supported by STFC Follow on Fund grant number ST/T003413/1
A mode-selective waveguide beam position monitor is under development. It is aimed primarily at electron linacs, although with its low impedance and wide bandwidth it could find alternative applications. In this paper we go over the design of the waveguide BPM system including the sensor and analog electronics, consider requirements to the digital processing and present some simulated results.
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MOP08  
About • Received ※ 09 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 29 November 2022
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MOP09 Towards Higher Stability in Large Scale Cavity BPM Systems 40
  • A. Lyapin, M.S. McCallum
    JAI, Egham, Surrey, United Kingdom
  • A. Aryshev, K.O. Kruchinin
    KEK, Ibaraki, Japan
  Funding: This work is supported by Royal Society International Exchanges Grant number IEC\R3\213050
In this contribution we consider a possible solution to long-term stability issues common in cavity BPM systems. The method will see a wider use active in-situ calibration systems injecting a tone into the measurement channel. We plan to compensate the bulk of the beam generated signal and so potentially extend the dynamic range of the electronics, reduce the amount of wakefield seen by the beam. The signal matching the real beam can then be used for mimicking the beam and calibrating out any drifts of the whole sensing and processing chain. We present the concept, give some simulated results and consider possible hardware solutions.
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MOP09  
About • Received ※ 07 September 2022 — Revised ※ 09 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 12 November 2022
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MOP10 Removing Noise in BPM Measurements with Variational Autoencoders 43
  • J.P. Edelen, J.A. Einstein-Curtis, C.C. Hall, M.J. Henderson
    RadiaSoft LLC, Boulder, Colorado, USA
  • A.L. Romanov
    Fermilab, Batavia, Illinois, USA
  Funding: This material is based upon work supported by the U.S. Department of Energy, Office of Science, Office of High Energy Physics under Award Number DE-SC0021699.
Noise in beam measurements is an ever-present challenge in accelerator operations. In addition to the challenges presented by hardware and signal processing, new operational regimes, such as ultra-short bunches, create additional difficulties in routine beam measurements. Techniques in machine learning have been successfully applied in other domains to overcome challenges inherent in noisy data. Variational autoencoders (VAEs) are shown to be capable of removing significant leevels of noise. A VAE can be used as a pre-processing tool for noise removal before the de-noised data is analyzed via other methods, or the VAE can be directly used to make beam dynamics measurements. Here we present the use of VAEs as a tool for addressing noise in BPM measurements.
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MOP10  
About • Received ※ 29 August 2022 — Revised ※ 10 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 24 November 2022
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MOP12 Production of Cavity Beam Position Monitors for the ARES Accelerator at DESY 47
  • D. Lipka, M. Holz, S. Vilcins
    DESY, Hamburg, Germany
  The SINBAD facility (Short and INnovative Bunches and Accelerators at DESY) hosts various experiments in the field of production of ultra-short electron bunches and novel high gradient acceleration techniques. The SINBAD facility, also called ARES (Accelerator Research Experiment at SINBAD), is a conventional S-band linear RF accelerator allowing the production of low charge ultra-short electron bunches within a range between 0.5 pC and 1000 pC. The positions of the low charge bunches will be detected by cavity beam position monitors. The principal design is based on the experience from the EU-XFEL cavity beam position monitors. It consists of a 316 LN stainless steel body with a design loaded quality factor of 70, a resonance frequency of 3.3 GHz and a relative wide gap of 15 mm to reach a high peak position sensitivity of 4.25 V/(nC mm). This poster covered, the manufacture of the individual mechanical parts, as well as presents the special features in the manufacture of customer designed UHV feedthroughs.  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MOP12  
About • Received ※ 05 September 2022 — Revised ※ 09 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 06 November 2022
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MOP13 Test and Measurements Results of the Pilot Tone Front End Industrialization for Elettra 2.0 51
  • G. Brajnik, R. De Monte
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • M. Cargnelutti, U. Dragonja, P. Leban, P. Paglovec, B. Repič, A. Vigali
    I-Tech, Solkan, Slovenia
  Elettra 2.0 will be the low-emittance upgrade of the present machine, a third-generation lightsource based in Trieste, Italy. The new machine, foreseen to be completed in 2025-2026, will be equipped with 168 beam position readout systems divided into 12 cells. The BPM electronics will be based on the prototypes developed by the laboratory, relying on the pilot-tone compensation technique for assuring the required resolution and long-term stability. The industrialization and production of the BPM electronics system are being carried out in partnership with Instrumentation Technologies, a company that has experience with BPM readout systems within the accelerator field. This paper will present the results of the industrialization of one of BPM system’s key component: the Pilot Tone Front End, focusing on its improvements introduced on electronic and mechanical sides, giving not only a significant performance gain with respect to the previous prototype but also improving robustness and reliability. An overview of the testing procedures that will assure the performance repeatability of the series will also be provided.  
poster icon Poster MOP13 [1.295 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MOP13  
About • Received ※ 30 August 2022 — Revised ※ 09 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 05 November 2022
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MOP14 Design and Implementation of an FPGA-Based Digital Processor for BPM Applications 55
  • M. Colja, S. Carrato
    University of Trieste, Trieste, Italy
  • G. Brajnik, R. De Monte
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  Digital processing systems have been proven to often outperform analog elaboration. Indeed, thanks to high-density DSPs and FPGAs, operations in digital domain give results that are impossible to achieve in other ways. On the other side, dealing with this great performance and flexibility is not always straightforward: the processing chain needs to be accurately planned to reach the desired goals, avoiding erratic behaviours in the digital domain. In this paper, we focus on the design and implementation of an FPGA-based digital processor that will be used in the electron beam position monitors of Elettra 2.0. After digitizing the 500 MHz beam signals from the pickups, the system executes a digital down conversion, followed by several filtering and demodulating stages, in order to have a selectable data rate that is suitable for both diagnostics and feedback. The position calculation is also performed in FPGA as well, with the well-known difference-over-sum algorithm. According to results provided by a fixed-point simulation, the overall system has been implemented in an Intel Arria 10 FPGA, demonstrating the correct design functionality that meets the specified requirements.  
poster icon Poster MOP14 [1.475 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MOP14  
About • Received ※ 06 September 2022 — Revised ※ 09 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 09 October 2022
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MOP15 Development of Non-Invasive Calibration Software for Front End X-Ray Beam Position Monitors at Diamond Light Source, Oxfordshire, UK 59
  • C.E. Houghton, C. Bloomer, L. Bobb
    DLS, Harwell, United Kingdom
  Tungsten blade based photoemission X-ray Beam Position Monitors (XBPMs) are widely used as white beam diagnostics at synchrotrons. Traditionally, the scale factors are determined by stepper motor movements of the XBPM, or by controlled electron beam displacements, and measuring the response. These measurements must be repeated for each ID gap to produce a complete set of scale factors for all operational conditions. This calibration procedure takes time and cannot be done while users are acquiring data. In addition, the scale factors can vary over time due to changes to the storage ring. It is possible for these scale factors to become inaccurate, reducing the accuracy of the beam position measured by the XBPMs. By using the intrinsic kHz electron beam movements and correlating the signals from electron beam position monitors and XBPMs it is possible to have a real-time calculation of the scale factors without the need to disturb user operation. Presented in this paper is a method to non-invasively calculate scale factors during normal user operation. A comparison of the precision of this method versus the traditional stepper motor method is presented.  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MOP15  
About • Received ※ 07 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 17 October 2022
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MOP43 Web-Based Application for Cable Simulation Models 156
  • M.C. Paniccia, S.L. Clark, D.M. Gassner, R.L. Hulsart, P. Thieberger
    BNL, Upton, New York, USA
  Attenuation in a lossy coaxial cable increases over distance and varies over frequency. Having a model of these variations can help predict the expected loss and distortion of a signal. This paper discusses a free web-based application developed to provide accurate SPICE models for various coaxial cable types. The user can specify a length and select between different cable types, or upload their own cable attenuation curve, and receive a SPICE model for that cable. These simulation models have been used to assist the design and development of new instrumentation systems for the future Electron Ion Collider (EIC).  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MOP43  
About • Received ※ 06 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 13 September 2022 — Issue date ※ 22 November 2022
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MOP44 Novel Photoemission Type X-Ray Beam Position Monitor for the "White" Undulator Radiation 159
  • P. Ilinski
    MAX IV Laboratory, Lund University, Lund, Sweden
  Funding: Research conducted at MAX IV, a Swedish national user facility, is supported by the Swedish Research council, the Swedish Governmental Agency for Innovation Systems, and Formas.
A novel photoemission type of X-ray Beam Position Monitor (XBPM) for the ’white’ undulator radiation is proposed. The XBPM employs beamline frontend fixed mask as a source of photocurrent signal. Signal spatial distribution and XBPM response were analyzed for various undulator radiation parameters.
poster icon Poster MOP44 [0.962 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MOP44  
About • Received ※ 02 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 12 September 2022 — Issue date ※ 19 September 2022
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Review of BPM Drift Effects and Compensation Schemes  
  • G. Rehm
    HZB, Berlin, Germany
  Apart from short term BPM resolution (repeatability), which aims at a few nm / sqrt(Hz) in modern systems, medium to long-term drift over durations of seconds to weeks (reproducibility) represents one of the challenges for BPM electronic developments. A number of approaches and compensation schemes have been developed and tested during the past years (e.g. cross-bar switching, pilot tone compensation, active temperature stabilization etc.) and experience has been gathered with environmental effects on electronics, cables and connectors. This talk will provide a review of drift effects and mitigation schemes for the next generation BPM systems.  
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slides icon Slides MO3I1 [6.535 MB]  
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MO3C2 Diamond-II Electron Beam Position Monitor Development 168
  • L.T. Stant, M.G. Abbott, L. Bobb, G. Cook, L. Hudson, A.F.D. Morgan, E.P.J. Perez Juarez, A.J. Rose, A. Tipper
    DLS, Oxfordshire, United Kingdom
  The UK national synchrotron facility, Diamond Light Source, is preparing for a major upgrade to the accelerator complex. Improved beam stability requirements necessitate the fast orbit feedback system be driven from beam position monitors with lower noise and drift performance than the existing solution. Short-term beam motion must be less than 2 nm/sqrt(Hz) over a period of one second with a data rate of 100 kHz, and long-term peak-to-peak beam motion must be less than 1 µm. A new beam position monitor is under development which utilises the pilot-tone correction method to reduce front-end and cabling perturbations to the button signal; and a MicroTCA platform for digital signal processing to provide the required data streams. This paper discusses the challenges faced during the design of the new system and presents experimental results from testing on the existing machine.  
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slides icon Slides MO3C2 [1.714 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MO3C2  
About • Received ※ 06 September 2022 — Revised ※ 11 September 2022 — Accepted ※ 12 September 2022 — Issue date ※ 17 October 2022
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MO3C3 Pulse-by-Pulse Photon Beam Position Measurements at the SPring-8 Undulator Beamline 173
  • H. Aoyagi, T. Fujita, K. Kobayashi, H. Osawa, S. Takahashi
    JASRI/SPring-8, Hyogo, Japan
  Funding: This work is partly supported by Japan Society for the Promotion of Science through a Grant-in-Aid for Scientific Research (c), No.18K11943, 21K12530.
This study analyzes a pulse-mode x-ray beam position monitor that enables pulse-by-pulse position measurement in a synchrotron radiation beamline of the synchrotron radiation facility, SPring-8. The monitor is equipped with blade-shaped detection elements utilizing diamond heatsinks to reduce stray capacitance and a microstripline transmission line to improve high-frequency characteristics. The detection elements operate as photocathodes and generate single unipolar pulses with a full width at half-maximum of less than 1 ns, allowing pulse-by-pulse measurement of the synchrotron radiation beam. We confirmed the basic operation of the monitor at the SPring-8 bending magnet beamline*. The detection element’s heat resistance consequently improved. An evaluation test was carried out at the SPring-8 undulator beamline with significantly high synchrotron radiation intensity. We aim to report the evaluation results of the sensitivity and resolution of the monitor measured by exciting a betatron oscillation in the horizontal/vertical direction using beam shakers of the SPring-8 storage ring and the observation results of the pulse-by-pulse photon beam dynamics induced by beam injection.
* https://journals.aps.org/prab/pdf/10.1103/PhysRevAccelBeams.24.032803
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slides icon Slides MO3C3 [1.574 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MO3C3  
About • Received ※ 07 September 2022 — Revised ※ 09 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 04 December 2022
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MO3C4 Beam Position Monitoring of Multi-bunch Electron Beams at the FLASH Free Electron Laser 177
  • N. Baboi, H.T. Duhme, B. Lorbeer
    DESY, Hamburg, Germany
  The superconducting FLASH user facility (Free electron LASer in Hamburg) accelerates 10 electron bunch trains per second, which are mostly used to produce high brilliance XUV and soft X-ray pulses. Each train usually contains up to 600 electron bunches with a typical charge between 100 pC and 1 nC and a minimum bunch spacing of 1 us. Various types of beam position monitors (BPM) are built in three electron beam lines, having a single bunch resolution of 2-100 um rms. This paper presents multi-bunch position measurements for various types of BPMs and built in at various locations. The dependency of the resolution on the beam offset is also shown.  
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slides icon Slides MO3C4 [1.551 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-MO3C4  
About • Received ※ 07 September 2022 — Revised ※ 09 September 2022 — Accepted ※ 13 September 2022 — Issue date ※ 17 November 2022
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TU1I1 Electro-Optical BPM Development for High Luminosity LHC 181
  • S.M. Gibson, A. Arteche
    Royal Holloway, University of London, Surrey, United Kingdom
  • T. Lefèvre, T.E. Levens
    CERN, Meyrin, Switzerland
  An Electro-Optic Beam Position Monitor (EO-BPM) is being developed as a high-frequency (up to 10 GHz) diagnostic for crabbing and Head-Tail intra-bunch detection at the HL-LHC. Following an earlier prototype at the SPS that demonstrated single-pickup signals, an upgraded design of an interferometric EO-BPM has been beam-tested at the HiRadMat facility for validation and characterisation studies. In the new design, the fibre-coupled Mach-Zehnder interferometer arms are modulated by lithium niobate waveguides integrated in an upgraded opto-mechanical arrangement that has been developed to produce a highly magnified image field replica of the passing Coulomb field. A new detection technique that is directly sensitive to the interferometric optical difference signal from opposite EO buttons has been applied to measure single-shot bunches for the first time. A transverse resolution study over a ±20 mm range at 3 GHz bandwidth produced the first successful electro-optic bunch-by-bunch position measurement at the HiRadMat in-air extraction line. The results of this campaign show promise for an in-vacuum design that is in production for beam tests at the SPS during Run-3 of the LHC.  
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slides icon Slides TU1I1 [26.286 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-TU1I1  
About • Received ※ 15 September 2022 — Revised ※ 17 September 2022 — Accepted ※ 25 October 2022 — Issue date ※ 30 November 2022
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TU1I2 Diagnostics with Quadrupole Pick-Ups at SIS18 186
  • A. Oeftiger, R. Singh
    GSI, Darmstadt, Germany
  The beam quadrupole moment of stored beams can be measured with a four-plate quadrupole pick-up. The frequency spectrum of the quadrupole moment contains not only the usual first-order dipole modes (the betatron tunes) but also the second-order coherent modes, comprising of (1.) (even) normal envelope modes, (2.) odd (skew) envelope modes and (3.) dispersion modes. As a novel diagnostic tool, the measured frequencies and amplitudes provide direct access to transverse space charge strength through the tune shift as well as linear coupling (and mismatch thereof), along with the benefit of a non-invasive beam-based measurement. Technically, quadrupole moment measurements require a pick-up with non-linear position sensitivity function. We discuss recent developments and depict measurements at the GSI SIS18 heavy-ion synchrotron.  
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slides icon Slides TU1I2 [8.866 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-TU1I2  
About • Received ※ 10 November 2022 — Accepted ※ 01 December 2022 — Issue date ※ 02 December 2022  
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Design and Simulation of Button Bpm for the Low Energy Storage Rings for Fourth Generration Light Sources  
  • Z.Q. Luo, Z. Liu
    HUST, Wuhan, People’s Republic of China
  Compared to 3rd-generation light sources, 4th-generation SR light sources improve the brightness by reducing the emittance of the electron beam. To ensure the extremely low emittance of electron beams, it is necessary to provide more accurate beam position measurement. Based on the BPM of the 3rd generation light source (SSRF), the design of button BPM for a diffraction-limited storage ring in the low-energy region of the 4th-generation light source is presented in this paper. Here we have focused on optimizing the BPM in terms of the basic structure sizes, the wakefield caused by electron beam transport and the voltage signals picked up by the electrodes, etc. The optimization improves the measurement resolution of BPM together with matching the requirements of beam position measurement proposed by the low energy storage ring.  
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TUP09 Design of the Beam Position Monitor for SOLEIL II 233
  • M. El Ajjouri, F. Alves, A. Gamelin, N. Hubert
    SOLEIL, Gif-sur-Yvette, France
  The Beam Position Monitors for the SOLEIL low emittance upgrade project are in the design phase. Efforts are put on the minimization of the heat load on the button by optimizing the longitudinal impedance and the BPM materials. To validate the mechanical design and tolerances a first prototype has been manufactured and controlled. This paper presents the mechanical design of the BPM, the metrology of the prototype and the lessons learned from this prototyping phase.  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-TUP09  
About • Received ※ 10 September 2022 — Revised ※ 11 September 2022 — Accepted ※ 13 September 2022 — Issue date ※ 07 November 2022
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TUP10 Development of a New Measurement System for Beam Position Pickups in the LINAC and Beam Energy Measurement (Time of Flight) in the MEBT for Medaustron 238
  • M. Repovž, M. Cerv, C. Kurfürst, G. Muyan, S. Myalski, A. Pozenel, C. Schmitzer, M. Wolf
    EBG MedAustron, Wr. Neustadt, Austria
  • A. Bardorfer, B. Baričevič, P. Paglovec, M. Škabar
    I-Tech, Solkan, Slovenia
  The MedAustron Ion Therapy Centre is a synchrotron-based particle therapy facility which delivers proton and carbon beams for clinical treatment. Currently, the facility treats roughly 40 patients per day and is improving its systems and workflows to further increase this number. MedAustron was commissioned and is operational without fully integrated systems for measurements of ’time of flight’ (beam energy) in the MEBT and beam position in the LINAC. This paper presents the newly developed system for these use cases, which will improve the overall commissioning and QA accuracy. It will unify the hardware used for the cavity regulation in the injector LLRF and the synchrotron LLRF. It will also be used for SYNC pickups, Schottky monitors and RF knock-out exciter. The new system is based on the CotS MicroTCA platform, which is controlled by the MedAustron Control System based on NI-PXIe. Currently it supports fiber-optic links (SFP+), but other links (e.g. EPICS, DOOCS) can be established. The modular implementation allows for connections to other components, such as motors, amplifiers, or interlock systems and will increase the robustness and maintainability of the accelerator.  
poster icon Poster TUP10 [2.590 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-TUP10  
About • Received ※ 04 September 2022 — Revised ※ 09 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 28 September 2022
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TUP11 A Cryogenic RF Cavity BPM for the Superconducting Undulator at LCLS 241
  • C.D. Nantista, A.A. Haase, P. Krejcik
    SLAC, Menlo Park, California, USA
  The new superconducting undulator beamline at LCLS requires the BPMs to be operated at cryogenic temperatures alongside the undulator magnets. They are used for beam-based alignment of the undulator magnets and quadrupole and require submicron resolution to achieve good FEL performance. This is to be achieved with X-band RF cavity BPMs, as is done now on the permanent undulator beamline. However, operating the cavities at cryogenic temperatures introduces significant challenges. We review the changes in RF properties of the cavities that result from cooling and how the design is changed to compensate for this. This includes a novel approach for employing a rectangular cavity with split modes to separately measure the X and Y position without coupling.  
poster icon Poster TUP11 [1.875 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-TUP11  
About • Received ※ 11 September 2022 — Revised ※ 12 September 2022 — Accepted ※ 13 September 2022 — Issue date ※ 11 November 2022
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TUP12 First Application of a Multiprocessing System-on-Chip BPM Electronics Platform at SwissFEL 245
  • B. Keil, R. Ditter, M. Gloor, G. Marinkovic, J. Purtschert
    PSI, Villigen PSI, Switzerland
  We have developed a new BPM electronics platform based on a MultiProcessing System-on-Chip (MPSoC). This contribution introduces the first application of the platform at the Paul Scherrer Institute (PSI), which is the cavity BPM system for the SwissFEL soft X-ray undulator beamline called ’Athos’ [1], where a larger number of systems are now operational. Measurement results and differences to the predecessor system will also be presented.  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-TUP12  
About • Received ※ 02 September 2022 — Revised ※ 12 September 2022 — Accepted ※ 13 September 2022 — Issue date ※ 26 September 2022
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TUP13 Standard Button BPMs for PETRA IV 249
  • S. Strokov, M. Holz, G. Kube, D. Lipka, S. Vilcins
    DESY, Hamburg, Germany
  A new diffraction limited light source PETRA IV (DESY, Germany) with ultra-low emittance is currently being designed as an upgrade of the 3rd generation light source PETRA III. For transverse beam position measurements, beam position monitors (BPMs) will be used as an essential part of the beam diagnostic system. There will be a total of about 800 BPMs distributed along the 2.3 km storage ring. The inner diameter of the standard beam pipe, and therefore of most of the BPM chambers, will be 20 mm. The primary purpose of the systems is to provide high-resolution measurements of the transverse position of the electron beam. By specification, the impact of the mechanical tolerances on the position readings should be below 150 microns which is essential for the commissioning of the machine. To achieve this goal, the dependence of the accuracy of the beam position measurement on the tolerances of each manufactured part of the BPM was studied. This paper summarizes the development and optimization of each part of the BPM by using EM simulations performed with CST Studio Suite.  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-TUP13  
About • Received ※ 07 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 12 September 2022 — Issue date ※ 01 October 2022
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WEP08 Upgrade of the BPM Long Term Drift Stabilization Scheme Based on External Crossbar Switching at PETRA III 395
  • G. Kube, F. Schmidt-Föhre, K. Wittenburg
    DESY, Hamburg, Germany
  • A. Bardorfer, L. Bogataj, M. Cargnelutti, P. Leban, M.O. Oblak, P. Paglovec, B. Repič
    I-Tech, Solkan, Slovenia
  PETRA IV at DESY will be an upgrade of the present synchrotron radiation source PETRA III into an ultra low-emittance source with beam emittance of about 20 pm.rad which imposes stringent requirements on the machine stability. In order to measure beam positions and control orbit stability to the required level of accuracy, a high resolution BPM system will be installed which consists of about 800 monitors with the readout electronics based on MTCA.4. In order to fulfill the requested long-term drift requirement (< 1 micron over 7 days), also the BPM cable paths have to be stabilized because of the PETRA-specific machine geometry. To achieve this, the crossbar switching concept was extended such that the analogue switching part is separated from the read-out electronics and brought as close as possible to the BPM pickup. While first measurements were presented before, meanwhile the system has undergone a major revision, especially the external switching matrix changed from a prototype setup to a system close to the final design. This contribution summarizes the latest measurements from PETRA III, demonstrating the high performance of the external stabilization concept.  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-WEP08  
About • Received ※ 07 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 18 October 2022
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WEP09 Preliminary Evaluation of the MTCA.4 BPM Electronics Prototype for the PETRA IV Project 399
  • P. Leban, A. Bardorfer, L. Bogataj, M. Cargnelutti, M.O. Oblak, P. Paglovec, B. Repič
    I-Tech, Solkan, Slovenia
  • G. Kube, F. Schmidt-Föhre, K. Wittenburg
    DESY, Hamburg, Germany
  Within the PETRA IV project at DESY, the synchrotron radiation source PETRA III will be upgraded into a low-emittance source. The small beam emittance and reduced beam size imply stringent requirements on the machine stability. To meet the requirements on position measurement and orbit stability, a high-resolution BPM system will be installed in the new machine, with about 800 BPMs and MTCA.4-based readout electronics. In the TDR phase of the project, I-Tech and DESY are cooperating on the realization of a BPM prototype that will demonstrate the feasibility of reaching the PETRA IV requirements. Several analog, digital and SW parts are taken from the Libera Brilliance+ instrument and are reused in the MTCA.4 BPM prototype, with some innovations. One of them is the separation of the RF switch matrix used for long-term stabilization: placing it near the BPM enables also the long RF cables to be stabilized. An 8 channel RTM board, able to acquire signals from two BPMs was developed and is also tested. This paper presents an overview of the BPM electronics prototype and the promising test results achieved in the Instrumentation Technologies’ laboratory with the first boards produced.  
poster icon Poster WEP09 [3.499 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-WEP09  
About • Received ※ 01 September 2022 — Revised ※ 11 September 2022 — Accepted ※ 12 September 2022 — Issue date ※ 23 September 2022
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WEP10 Detection of a DC Electric Field Using Electro-Optical Crystals 403
  • A. Cristiano, M. Krupa
    CERN, Meyrin, Switzerland
  • R. Hill
    University of Huddersfield, Huddersfield, United Kingdom
  Standard beam position monitors (BPM) are intrinsically insensitive to beams with no temporal structure, so-called DC beams, which many CERN experiments rely on. We therefore propose a novel detection technique in which the usual BPM electrodes are replaced with electro-optic (EO) crystals. When exposed to an electric field, such crystals change their optical properties. This can be exploited to encode the electric field magnitude onto the polarisation state of a laser beam crossing the crystal. An additional EO crystal, placed outside the vacuum chamber, can be used to control the system’s working point and to introduce a sinusoidal modulation, allowing DC measurements to be performed in the frequency domain. This contribution presents the working principle of this measurement technique, its known limitations, and possible solutions to further increase the system’s performance. Analytical results and simulations for a double-crystal optical chain are benchmarked against the experimental data taken on a laboratory test bench.  
poster icon Poster WEP10 [0.940 MB]  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-WEP10  
About • Received ※ 07 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 15 September 2022 — Issue date ※ 03 December 2022
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Beam Based Calibration of Button Type Beam Position Monitor at MEBT of RAON  
  • J.W. Kwon, G.D. Kim
    IBS, Daejeon, Republic of Korea
  • E.H. Lim
    Korea University Sejong Campus, Sejong, Republic of Korea
  The RAON(Rare-isotope Accelerator complex for ON-line experiments) is an accelerator for heavy ions, such as uranium, oxygen and argon. 60 button beam position monitors was fabricated for the SCL3 that accelerate and deliver the beam from 0.5 MeV/u to 18.5 MeV/u in a uranium case. The beam has bunch structure after the RFQ at 0.5 MeV/u, the lowest energy measurable by BPM. Developed electronics measure positions using IQ method for 1st, 2nd and 3rd harmonic frequencies of 81.25 MHz. Calibration factors of BPM for the three frequency harmonic components were obtained taking into account the frequency dependence of the electronics at wire test bench. To measure the correction factor based on the acceleration beam, a movable stage equipped with a micrometer was prepared on a one-dimensional plane. We present the beam-based calibration test results of button-type BPM for low-beta and heavy-ion beams at MEBT of RAON.  
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WEP12 HL-LHC BPM System Development Status 408
  • M. Krupa, I. Degl’Innocenti, D. Gudkov, G. Schneider
    CERN, Meyrin, Switzerland
  • D.R. Bett
    JAI, Oxford, United Kingdom
  The demanding instrumentation requirements of the future High Luminosity LHC (HL-LHC) require 44 newly designed Beam Position Monitors (BPM) to be installed around the ATLAS and CMS experiments in 2026-2028. Three BPM types are now in pre-series production, with two more variants under design. Close to the collision point, a set of cryogenic directive coupler BPMs equipped with a brand new acquisition system based on nearly-direct digitization will resolve the position of the two counter-rotating LHC beams occupying a common vacuum chamber. Other new button and stripline BPMs will provide not only the transverse beam position, but also timing signals for the experiments, and diagnostics for the new HL-LHC crab cavities. This contribution summarizes the HL-LHC BPM specifications, gives an overview of the new BPM designs, reports on the pre-series BPM production status and plans for series manufacturing, outlines the foreseen acquisition system architecture, and highlights the first beam measurements carried out with the proof-of-concept electronics for the directive stripline BPMs.  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-WEP12  
About • Received ※ 09 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 11 September 2022 — Issue date ※ 03 October 2022
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Status of the uTCA Digitizer BPM Design for SARAF Phase II  
  • P. Gil, J. Fernández
    7S, Peligros (Granada), Spain
  • G. Desmarchelier, R.D. Duperrier
    CEA-DRF-IRFU, France
  • G. Ferrand, N. Pichoff, C. Simon
    CEA-IRFU, Gif-sur-Yvette, France
  One of the crucial monitoring systems of any particle accelerator is the Beam Position Monitor (BPM). The purpose of a BPM is to provide information on the position, phase and current of the beam along the accelerator line. CEA Saclay must provide all beam diagnostics for SARAF-LINAC PHASE II in particular BPM. Based on the technical specifications of the CEA, Orolia-Spain is in charge of the design, development, manufacture and testing of the electronic system. A preliminary version of this system has been already tested at Orolia’s and CEA installations and the first results are going to be shown. The architecture, design and development as well as the performance of the BPM system will be presented in this paper. The benefits of the proposed architecture and the first results obtained under different conditions will be detailed  
poster icon Poster WEP13 [0.972 MB]  
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WEP14 Cavity BPM Electronics for SINBAD at DESY 413
  • B. Lorbeer, H.T. Duhme, I. Krouptchenkov, T. Lensch, D. Lipka, S. Vilcins, M. Werner
    DESY, Hamburg, Germany
  The SINBAD(Short and INnovative Bunches and Accelerators at DESY ) R&D accelerator is planned for studying new concepts for high gradient electron beam acceleration and the generation of ultra-short electron bunches. The accelerator called ARES(Accelerator Research Experiment At DESY) is composed of S-band accelerating structures. In order to achieve the goal of very short electron bunches the electron beam charges generated in the RF Gun can vary in a range from 1nC down to 500fC. In order to measure the beam position with good resolution at the small charge end of 500fC a new cavity BPM(beam position monitor) has been developed. One key component in the BPM system is the custom RF electronics to meet the resolution requirements in the entire charge range. The entire BPM system with a focus on the system design requirements and the utca based RF electronics are presented in this paper.  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-WEP14  
About • Received ※ 07 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 12 September 2022 — Issue date ※ 12 December 2022
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WEP15 XFEL Photon Pulse Measurement Using an All-Carbon Diamond Detector 416
  • C. Bloomer, L. Bobb
    DLS, Oxfordshire, United Kingdom
  • W. Freund, J. Grünert, J. Liu
    EuXFEL, Schenefeld, Germany
  • M.E. Newton
    University of Warwick, Coventry, United Kingdom
  The European XFEL can generate extremely intense, ultra-short X-ray pulses at MHz repetition rates. Single-crystal CVD diamond detectors have been used to transparently measure the photon beam position and pulse intensity. The diamond itself can withstand the power of the beam, but the surface electrodes can be damaged since a single pulse can already exceed the damage threshold of the electrode material. Presented in this work are pulse intensity and position measurements obtained at the European XFEL using a new type of all-carbon single-crystal diamond detector developed at Diamond Light Source. Instead of traditional surface metallisation, the detector uses laser-written graphitic electrodes buried within the bulk diamond. There is no metallisation in the XFEL X-ray beam path that could be damaged by the beam. The results obtained from a prototype detector are presented, capable of measuring the intensity and 1-dimensional X-ray beam position of individual XFEL pulses. These successful measurements demonstrate the feasibility of all-carbon diagnostic detectors for XFEL use.  
DOI • reference for this paper ※ doi:10.18429/JACoW-IBIC2022-WEP15  
About • Received ※ 07 September 2022 — Revised ※ 10 September 2022 — Accepted ※ 12 September 2022 — Issue date ※ 23 September 2022
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