IBIC2023 - Classification: 02 Beam Position Monitors

Paper	Title	Page
MO3I01	The Art of Sensing Beam Orbits in Mile-long Accelerators on a Nanometer Scale
	D. Padrazo BNL, Upton, New York, USA
	The "eyes" that enable us to see the particle beams are called Beam Position Monitors. BPM design is based on detection of electric fields of the bunches passing through electrodes located inside the vacuum chamber. The weak electric signals are filtered, amplified and digitized to provide us with the orbit data. The progress with advancing the BPM accuracy, sensitivity, speed and data volume has escalated manyfold in the last few decades following the rapid growth of capabilities of the modern electronics. In my presentation I will go over the basic principles, the history and the future prospects of BPM diagnostics for particle accelerators. Concurrently I will introduce our home-grown solution for NSLS-II RF BPMs and present the accomplishments to date, experience from operations and studies and an outlook at the future developments in both Analog and Digital domains of our devices. NSLS-II has 250 BPMs that include several generations and our units demonstrate an outstanding level of both reliability and performance.
	Slides MO3I01 [8.998 MB]
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MO3I02	Dielectric Pick-Up for Short Bunches
	E. Senes, T. Lefèvre CERN, Meyrin, Switzerland
	Novel acceleration schemes pose new challenges to the beam instrumentation required. This contribution presents a novel device to measure the beam position, enabling the discrimination of different co-propagating beams. The method leverages the characteristic properties of the Coherent Cherenkov-Diffraction Radiation (ChDR) emitted from dielectric inserts in the beampipe. The beam discrimination is performed in the frequency domain, exploiting the bunch length difference of the two beams. This device was developed for the AWAKE experiment, where not only an electron beam co-propagates with a more intense proton beam, but also traditional pickups are impacted by the environment polluted with spurious charges from the plasma. The electron beam discrimination takes place in a narrow band around 30 GHz. The overall design and results from the AWAKE experiment are presented. The utilisation of coherent ChDR to distinguish different co-propagating beams is a substantial novelty in the field, pushing the instruments capabilities for novel accelerating technologies, such as plasma-based accelerators.
	Slides MO3I02 [8.860 MB]
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MO3C03	Development of the SLS 2.0 BPM System	15
	B. Keil, R. Ditter, F. Marcellini, G.M. Marinkovic, J. Purtschert, M. Rizzi, M. Roggli, D. Stephan, X. Wang PSI, Villigen PSI, Switzerland
	After more than 20 years of operation, the storage ring of the Swiss Light Source (SLS) will be replaced. The new ring called SLS 2.0 will have 40 times higher brilliance than SLS, thanks to an innovative low-emittance magnet lattice and a beam pipe with smaller aperture. For SLS 2.0, the ageing SLS BPM electronics will be incrementally replaced for the whole accelerator, including linac, booster, transfer lines and storage ring. This contribution presents the development status and latest prototype test results of the SLS 2.0 BPM system, including BPM pickups, mechanics, and electronics.
	Slides MO3C03 [5.240 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MO3C03
About •	Received ※ 09 September 2023 — Revised ※ 10 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 21 September 2023
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MO3C04	A MTCA Based BPM-System for PETRA IV	19
	G. Kube, H.T. Duhme, J.L. Lamaack, 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
	The PETRA IV project aims to upgrade the present PETRA III synchrotron into an ultra low-emittance source. The small emittances translate directly into much smaller beam sizes, thus imposing stringent requirements on the machine stability. In order to measure beam positions and control orbit stability to the level of 10% of beam size and divergence, a high resolution BPM system will be installed which consists of 788 individual monitors with the readout electronics based on MTCA.4. In order to fulfil the long-term drift requirement (< 1 micron over 7 days), several analog, digital and SW parts were taken from the Libera Brilliance⁺ and a new RTM module has been developed to be used as BPM electronics RFFE. In addition, its analogue RF switch matrix used for long-term stabilization was separated and placed close to the BPM pickup, hence enabling an additional stabilization of the RF cables. At present, a fully populated MTCA crate with 6 AMC boards for the readout of 12 BPMs is installed at PETRA III and is extensively being tested. This contribution summarizes the latest beam measurements, demonstrating the high performance of the BPM system and the external stabilization concept.
	Slides MO3C04 [3.604 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MO3C04
About •	Received ※ 06 September 2023 — Revised ※ 10 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 02 October 2023
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MO3C05	Canadian Light Source Beam Position Visualization Tool	24
	M. Bree, T. Batten, C.W. Stevens, J.M. Vogt CLS, Saskatoon, Saskatchewan, Canada
	The CLS Orbit Correction (OC) system acquires, collates, and publishes storage ring beam centroid position information from 48 beam position monitors (BPMs) at a rate of 1000 samples per second. We present a "Storage Ring Beam Position Visualization Tool" that computes and displays dynamic Fast Fourier Transforms (FFTs) and Cumulative Power Spectral Densities (CPSDs) for all BPMs in real-time using full resolution data. The computed FFTs and CPSDs can be plotted in various combinations and in waterfall plots that allow visualization of changes over long periods of time. In addition, correlations between all BPM channel combinations are computed and ranked. Data from any two BPM channels can be selected for plotting in two dimensions wherein correlations are visually apparent. Computed CPSDs are further binned and published in scalar EPICS PVs which are archived for further analysis. Preliminary results from the Beam Position Visualization Tool have proven useful in characterizing beam position noise at the CLS.
	Slides MO3C05 [197.014 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MO3C05
About •	Received ※ 17 July 2023 — Revised ※ 16 August 2023 — Accepted ※ 13 September 2023 — Issue date ※ 26 September 2023
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MOP013	Expansion of the MTCA Based Direct Sampling LLRF at MedAustron for Hadron Synchrotron Applications	63
	M. Wolf, M. Cerv, C. Kurfürst, S. Myalski, M. Repovž, C. Schmitzer EBG MedAustron, Wr. Neustadt, Austria A. Bardorfer, B. Baričevič, P. Leban, P. Paglovec, M. Škabar I-Tech, Solkan, Slovenia
	The MedAustron Ion Therapy Centre is a synchrotron-based particle therapy facility located in Lower Austria, which delivers proton and carbon ion beams for cancer treatments. Currently the facility treats over 400 patients per year and is expected to double this number in the future. Six years since the start of clinical operation, MedAustron is experiencing end-of-life issues concerning the digital Low Level RF components in the injector and the synchrotron. Replacements for these applications are under development and the chosen hardware is suitable to also update multiple beam diagnostic devices in the facility. Main targets for updates are the Schottky monitors, which were never properly integrated into the MedAustron Control system and the position pickup measurement system, which currently does not support turn by turn measurements. Comparison measurements with other state of the art diagnostic devices are ongoing to demonstrate the capabilities of the generic hardware. Furthermore, these measurements should show the increased usability and diagnostic potential compared to the legacy devices.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP013
About •	Received ※ 07 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 16 September 2023
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MOP015	RF Calibration and Distribution devices for SPIRAL2 BPMs
	C. Jamet, T. Andre, P. Legallois, S. Leloir, C. Potier de courcy GANIL, Caen, France
	In order to achieve the required measurement accuracy for the SPIRAL2 BPMs in positions, ellipticities and phases, new RF Calibration and Distribution devices were developed, tested and installed on the SPIRAL2 Facility in 2022. Accuracy measurements depends on gain and phase differences of the 4 BPM measurement channels. In order to compensate analogic differences, digital corrections are applied in function of the calibration results. One of the main objectives was to automate the different steps of the calibration process in order to reduce the calibration time and avoid cable connections and disconnections. The second objective was to distribute RF reference signals to all BPM electronics cards with the same amplitudes and phases. This document describes technical solutions and qualifications performed, explains the calibration process, corrections and results obtained.
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MOP018	Beam-diagnostic and T0 System for the mCBM and CBM Experiments at GSI and FAIR	66
	A. Rost, A. Senger FAIR, Darmstadt, Germany T. Galatyuk, M. Kis, J. Pietraszko, J. Thaufelder, F. Ulrich-Pur GSI, Darmstadt, Germany T. Galatyuk, V. Kedych, W. Krüger TU Darmstadt, Darmstadt, Germany
	Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 871072. The Compressed Baryonic Matter (CBM) experiment at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt requires a highly accurate beam monitoring and time-zero (T0) system. This system needs to meet the requirements of the CBM time-of-flight (ToF) measurement system for both proton and heavy ion beams, while also serving as part of the fast beam abort system. To achieve these goals, a detector based on chemical vapor deposition (CVD) diamond technology has been proposed. In addition, new developments using Low Gain Avalanche Detectors (LGADs) are currently under evaluation. This contribution presents the current development status of the beam detector concept for the CBM experiment.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP018
About •	Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 30 September 2023
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MOP019	First Test with MicroTCA Based Cavity BPM Electronics for the European XFEL and FLASH	70
	B. Lorbeer, H.T. Duhme, I. Krouptchenkov, T. Lensch, D. Lipka, M. Werner DESY, Hamburg, Germany
	The European X-ray free-electron laser (E-XFEL) and the FLASH2020+ project for the free electron laser Hamburg (FLASH) at DESY in Hamburg, Germany foresee several machine upgrades in the years to come. At FLASH a whole undulator section in a shutdown starting in summer 2024 and finishing in autumn 2025 is going to be rebuild. Existing button beam position monitors installed in this section of the machine do not deliver sufficient signal strength for future required resolution specification and orbit feedback optimization for machine operation. The resolution limitations will be overcome by replacing the button-based beam position monitors with in-house developed cavity beam position monitors and compact microTCA based radio frequency receiver read-out electronics. The measurement system has been tested and evaluated in a test setup at FLASH.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP019
About •	Received ※ 05 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 21 September 2023 — Issue date ※ 30 September 2023
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MOP021	New Beam Position Monitor System for PETRA IV
	J.L. Lamaack University of Hamburg, Hamburg, Germany A. Bardorfer, L. Bogataj, M. Cargnelutti, P. Leban, M.O. Oblak, P. Paglovec, B. Repič I-Tech, Solkan, Slovenia H.T. Duhme, G. Kube, F. Schmidt-Föhre, K. Wittenburg DESY, Hamburg, Germany
	The PETRA IV project at DESY aims to upgrade the present synchrotron radiation source PETRA III into a source of ultra-low emittance with target emittance of 20 pmrad. The small beam emittance translates directly into much smaller beam sizes of about 7 microns horizontally and 3 microns vertically at insertion device source points, thus imposing stringent requirements on the machine’s stability. In order to measure beam position and control orbit stability to the required level of accuracy, a high-resolution BPM system consisting of 790 individual monitors will be installed. Its readout electronics will be based on MTCA.4 as a technical platform. To fulfill the long-term drift requirement (< 1 micron over 7 days), the concept of crossbar-switching was extended in such a way that the RF switch matrix is separated from the readout electronics and placed as close to the BPM pickup as possible, therefore enabling additional stabilization of the RF cables. At present, a fully populated MTCA.4 crate with 6 AMC boards for the readout of 12 BPMs is installed at PETRA III and extensively tested. This contribution summarizes the latest measurements of the long term stability.
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MOP022	Replacement of the Single-Pass BPM System with MicroTCA.4-based Versatile Electronics at SPring-8	74
	H. Maesaka, N. Hosoda, S. Takano RIKEN SPring-8 Center, Hyogo, Japan H. Dewa, T. Fujita, N. Hosoda, H. Maesaka, M. Masaki, S. Takano JASRI, Hyogo, Japan
	We have developed MicroTCA.4-based versatile BPM readout electronics for the SPring-8 upgrade project, SPring-8-II (). The input signals are processed by an rf front-end rear transition module (RTM) with band-pass filters, amplifiers, and step attenuators and digitized by 16-bit 370 MSPS high-speed digitizers on an advanced mezzanine card (AMC). The field-programmable gate array (FPGA) on the AMC calculates both single-pass and COD beam positions. The current BPM system at SPring-8 consists of approximately twenty single-pass dedicated BPMs and over two hundred other COD dedicated ones. In advance of SPring-8-II, so far, we renewed half of the single-pass dedicated BPM electronics to the MicroTCA.4. A graphical user interface (GUI) for the new BPM system was also developed and ready for tuning. The single-pass BPM resolution was confirmed to be better than 100 um for a 100 pC single bunch, sufficient for SPring-8-II. The other existing single-pass BPM electronics will also be renewed this summer. The full renewal of remaining COD dedicated BPM electronics to the versatile MicroTCA.4 ones is planned in the subsequent years before the construction of SPring-8-II. () H. Maesaka et al., "Development of MTCA.4-based BPM Electronics for SPring-8 Upgrade", Proc. IBIC’19, doi:10.18429/JACoW-IBIC2019-WEBO03
	Poster MOP022 [1.074 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP022
About •	Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 30 September 2023
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MOP023	The Conceptual Design Study for New BPM Signal Processing System of J-PARC (MR)	78
	K. Satou, T. Toyama, S. Yamada KEK, Tokai, Ibaraki, Japan
	The BPM signal processing system, which is19 years old system, have been suffering from gain fluctuation due to contact resistance of the mechanical gain selector, communication disruption caused by an unstable contact of a card edge connector. In addition, it has a difficulty of repairments because some on-board parts have already reached end of product-life cycle, and some units have been in unusable situation. Presently, we are on the beam power upgrade campaign to 1.3 MW by increasing beam bunch current and shortening the MR operation cycle, and precise beam tunings would require massive waveform data processing and transfer to a storage than the present system. For this, we have been developing the system based on the 10 GbE optical link. The ADC board which is under development would perform direct sampling using the third harmonic of RF. The digital IQ demodulation technique is used to extract the baseband oscillation from the raw data. The obtained raw waveform as well as closed orbit data would be stored in the data storage system. In the presentation, we will report on the progress of development aimed at operation in 2025 and the conceptual design of the new system.
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP023
About •	Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 19 September 2023
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MOP024	The Design and Optimization of Digital Beam Position Monitor Processor in HEPS
	Y.Y. Du, J.S. Cao, Z. Liu, Y.F. Sui, S.J. Wei, Q. Ye, J.H. Yue IHEP, Beijing, People’s Republic of China
	The Digital Beam Position Monitor (DBPM) is an important component of the High Energy Photon Source (HEPS). This article mainly introduces the design and development of the digital beam position measurement system based on the main indicators of HEPS, including the overall architecture design of the system, digital electronics design, RF electronics design, and the exposition of core algorithm design. It also provides a detailed performance comparison between the two versions of electronic design before and after optimization, including performance indicators such as flow-dependent, long-term stability, and position resolution. In laboratory testing, under the condition of an input signal of 499.8MHz and K factor is 8.26, the position resolution per turn by turn (TBT) is less than 1um, the fast orbit position resolution (FA) is less than 100nm, and the closed orbit position resolution (SA) is less than 10nm. The beam current-dependence and long-term stability are significantly better than the previous version, and the test results meet the design requirements of the High Energy Photon Source.
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MOP026	A Novel BPM Mechanical Center Calibration Method Based on Laser Ranging	82
	X.H. Tang, J.S. Cao, Y.Y. Du, J. He, Y.F. Sui, J.H. Yue IHEP, Beijing, People’s Republic of China
	Determining the mechanical center of the beam position monitor(BPM) has been a difficulty for BPM calibration. To solve this problem, a method of positioning the BPM mechanical center based on laser ranging is proposed. This method uses high-precision antenna support as the core locating datum, and high-precision laser ranging sensors(LRSs) as the detection tool. By detecting the distances from the LRSs to the antenna support and the distances from the LRSs to the BPM, the mechanical center of the BPM can be indirectly determined. The theoretical system error of this method is within 20¿m, and the experimental results show that the measurement repeatability is less than 40¿m, This method has low cost and fast speed, which can be used for large-scale calibration.
	Poster MOP026 [1.142 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP026
About •	Received ※ 13 July 2023 — Revised ※ 07 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 26 September 2023
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MOP028	The Design of Button Beam Position Monitor for Shenzhen Innovation Light-Source Facility
	T. Yu IASF, Shenzhen, Guangdong, People’s Republic of China
	Shenzhen Innovation Light-source Facility (SILF) is a brand new project supported by the Chinese government to build a 4th generation synchrotron radiation source whose storage ring is so-called diffraction-limited. The beam design is that the emission is less than 100 pm·rad, and the beam instability is less than 10% of the beam spot. Therefore, the revolution of the beam position monitor (BPM) needs to be less than 0.12 ¿m for closed orbit detection. In order to achieve such excellent resolution, the signal-to-noise ratio of the BPM output signal in the 10MHz bandwidth is required to be better than 66dB. After the finite element numerical analysis, the diameter of the pickup electrode will be 8mm, and the gap between the electrode and the vacuum chamber will be 0.3 mm.
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MOP029	A Novel Design of a Dielectric-filled Cavity BPM for HUST-PTF
	J.Q. Li, K. Fan, J. Wang HUST, Wuhan, People’s Republic of China
	To guarantee proton therapy safety and effectivity, non-invasive beam diagnostic¿NBD¿ devices are mandatory to precisely monitor the beam parameters during patient treatment. However, the clinical proton beams have characters of low currents and frequencies, which impose challenges for the design to improve the diagnosis resolution. A dielectric-filled racetrack cavity-type BPM has been studied deeply to compact its size while maintaining high diagnosis sensitivity. Moreover, the cross-talk between X and Y directions is effectively suppressed to ensure the diagnosis precision. The simulation and calculation results show that the cavity BPM has sufficient position sensitivity and signal-to-noise ratio. The signal-to-noise ratio can ba as large as 16.2 even when the beam intensity is 0.35 nA. The design studies results show that the dielectric-filled racetrack cavity is a potential candidate for a non-destructive beam position detector in HUST-PTF.
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MOP030	Developments of 4GSR BPM Electronics	87
	S.W. Jang, G. Hahn, J.Y. Huang, C. Kim, D. Kim, G. Kim, B.K. Shin, D.C. Shin, D. Song PAL, Pohang, Republic of Korea W.J. Song POSTECH, Pohang, Republic of Korea
	The emittance of the 4th-generation storage ring (4GSR) to be constructed in Cheongju-Ochang, Korea, is expected to be approximately 100 times smaller than the existing 3rd-generation storage ring. With the decrease in emittance, more precise beam stabilization is required. To meet this requirement, the resolution of the beam position monitor (BPM) system also needs to be further improved. We have conducted research and development on the electronics of the BPM system for the 4GSR storage ring. In order to perform fast orbit feedback in the 4GSR storage ring, we need to acquire turn-by-turn beam position data, with a desired beam position resolution of 1 ¿m. Additionally, prototypes of the bunch-by-bunch monitoring system are being developed for the transverse feedback system and longitudinal feedback system. The internally developed electronics are intended to be modified for future use as monitors for multi-bunch beam energy measurements at the end of the linear accelerator, by adjusting the logic accordingly. In this presentation, we will describe more details of the current status of the development of the beam position monitor electronics for the 4GSR in Korea.
	Poster MOP030 [24.607 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP030
About •	Received ※ 05 September 2023 — Revised ※ 11 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 19 September 2023
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MOP031	A Study Into the Long-Term Stability of Front End X-Ray Beam Position Monitor Support Columns at Diamond Light Source	90
	C.E. Houghton, C. Bloomer, L. Bobb, D. Crivelli, J.E. Melton, H. Patel DLS, Harwell, United Kingdom
	Sand-filled steel columns are used at Diamond Light Source to support front end X-ray beam position monitors. This approach is chosen due to the relatively large thermal mass of the sand being considered useful to reduce the rate at which expansion and contraction of the column occurred as the storage ring tunnel temperature varied, particularly during machine start-up. With the higher requirements for mechanical stability for the upcoming Diamond-II upgrade, there is now a need to assess and quantify the current system’s impact on X-ray beam movement. A study of thermal and mechanical stability has been carried out to quantify the stability performance of the front end X-ray beam position monitor’s columns and the impact that column motion may have on the X-ray beam position measurement. Measurements have been made over a range of different timescales, from 250 Hz up to 2 weeks. The measured stability of the support column is presented, showing that it meets our Diamond-II stability requirements. A comparison of the stability of the column with and without a sand filling is presented.
	Poster MOP031 [0.594 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP031
About •	Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 17 September 2023
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MOP032	One Dimensional Beam Position Monitor Prototype using Incoherent Cherenkov Diffraction Radiation	94
	A.J. Clapp Royal Holloway, University of London, Surrey, United Kingdom L. Bobb, G. Cook DLS, Oxfordshire, United Kingdom P. Karataev JAI, Egham, Surrey, United Kingdom
	This paper proposes a novel advancement in both the studies of Cherenkov diffraction radiation (ChDR) and beam instrumentation. The proposed beam position monitor (BPM) consists of two identical fused Silica prism radiators, with a fibre collimator attached to each one, which in turn are connected to a photodetector via a series of optical fibres. The setup will be implemented into the booster to storage ring transfer line at Diamond Light Source ¿ an electron light source with 3 GeV beam energy. The prototype proposed aims to test the feasibility of a full BPM utilising ChDR. If proven to be fully realisable, optical rather than capacitive BPM pickups could be more widely distributed. The paper will include the complete design and preliminary results of a one-dimensional BPM, utilising the ChDR effect.
	Poster MOP032 [2.516 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP032
About •	Received ※ 26 August 2023 — Revised ※ 07 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 27 September 2023
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MOP033	1L Target Harp Diagnostic Display Tool	99
	A.D. Walker, E.L. Kerstiens LANL, Los Alamos, New Mexico, USA
	The Los Alamos Neutron Science Center (LANSCE) completed upgrades to its 1L Target Facility, which included installing the new Mark IV target assembly. This added a third tungsten target located upstream of the other two targets. Prior to Mark IV, beam centering on target was achieved by using thermocouples mounted to the quadrants and center of the upper target coolant chamber. It is slightly offset from center of the old upper target and it shadows several of the thermocouples previously used to center beam on target. This required adjustments to the diagnostic tools utilized to monitor position of the H⁻ beam that is being delivered to the 1L target. The original display included the thermocouple readouts and displayed a visual beam profile and position taken from an upstream harp. With some of the thermocouples now being shadowed, an image overlay was added to show where the harp¿s measured beam position is relative to both the upper and middle targets. This gives the beam operations team an additional level of awareness when it comes to thermocouple temperatures, beam steering, and beam tuning. Details of the display tool and its associated upgrades are presented. LANL Report #: LA-UR-23-25004
	Poster MOP033 [0.825 MB]
DOI •	reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP033
About •	Received ※ 05 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 20 September 2023
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Paper

Title

Page

MO3I01

The Art of Sensing Beam Orbits in Mile-long Accelerators on a Nanometer Scale

D. Padrazo
BNL, Upton, New York, USA

The "eyes" that enable us to see the particle beams are called Beam Position Monitors. BPM design is based on detection of electric fields of the bunches passing through electrodes located inside the vacuum chamber. The weak electric signals are filtered, amplified and digitized to provide us with the orbit data. The progress with advancing the BPM accuracy, sensitivity, speed and data volume has escalated manyfold in the last few decades following the rapid growth of capabilities of the modern electronics. In my presentation I will go over the basic principles, the history and the future prospects of BPM diagnostics for particle accelerators. Concurrently I will introduce our home-grown solution for NSLS-II RF BPMs and present the accomplishments to date, experience from operations and studies and an outlook at the future developments in both Analog and Digital domains of our devices. NSLS-II has 250 BPMs that include several generations and our units demonstrate an outstanding level of both reliability and performance.

Slides MO3I01 [8.998 MB]

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MO3I02

Dielectric Pick-Up for Short Bunches

E. Senes, T. Lefèvre
CERN, Meyrin, Switzerland

Novel acceleration schemes pose new challenges to the beam instrumentation required. This contribution presents a novel device to measure the beam position, enabling the discrimination of different co-propagating beams. The method leverages the characteristic properties of the Coherent Cherenkov-Diffraction Radiation (ChDR) emitted from dielectric inserts in the beampipe. The beam discrimination is performed in the frequency domain, exploiting the bunch length difference of the two beams. This device was developed for the AWAKE experiment, where not only an electron beam co-propagates with a more intense proton beam, but also traditional pickups are impacted by the environment polluted with spurious charges from the plasma. The electron beam discrimination takes place in a narrow band around 30 GHz. The overall design and results from the AWAKE experiment are presented. The utilisation of coherent ChDR to distinguish different co-propagating beams is a substantial novelty in the field, pushing the instruments capabilities for novel accelerating technologies, such as plasma-based accelerators.

Slides MO3I02 [8.860 MB]

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MO3C03

Development of the SLS 2.0 BPM System

15

B. Keil, R. Ditter, F. Marcellini, G.M. Marinkovic, J. Purtschert, M. Rizzi, M. Roggli, D. Stephan, X. Wang
PSI, Villigen PSI, Switzerland

After more than 20 years of operation, the storage ring of the Swiss Light Source (SLS) will be replaced. The new ring called SLS 2.0 will have 40 times higher brilliance than SLS, thanks to an innovative low-emittance magnet lattice and a beam pipe with smaller aperture. For SLS 2.0, the ageing SLS BPM electronics will be incrementally replaced for the whole accelerator, including linac, booster, transfer lines and storage ring. This contribution presents the development status and latest prototype test results of the SLS 2.0 BPM system, including BPM pickups, mechanics, and electronics.

Slides MO3C03 [5.240 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MO3C03

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Received ※ 09 September 2023 — Revised ※ 10 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 21 September 2023

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MO3C04

A MTCA Based BPM-System for PETRA IV

19

G. Kube, H.T. Duhme, J.L. Lamaack, 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

The PETRA IV project aims to upgrade the present PETRA III synchrotron into an ultra low-emittance source. The small emittances translate directly into much smaller beam sizes, thus imposing stringent requirements on the machine stability. In order to measure beam positions and control orbit stability to the level of 10% of beam size and divergence, a high resolution BPM system will be installed which consists of 788 individual monitors with the readout electronics based on MTCA.4. In order to fulfil the long-term drift requirement (< 1 micron over 7 days), several analog, digital and SW parts were taken from the Libera Brilliance⁺ and a new RTM module has been developed to be used as BPM electronics RFFE. In addition, its analogue RF switch matrix used for long-term stabilization was separated and placed close to the BPM pickup, hence enabling an additional stabilization of the RF cables. At present, a fully populated MTCA crate with 6 AMC boards for the readout of 12 BPMs is installed at PETRA III and is extensively being tested. This contribution summarizes the latest beam measurements, demonstrating the high performance of the BPM system and the external stabilization concept.

Slides MO3C04 [3.604 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MO3C04

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Received ※ 06 September 2023 — Revised ※ 10 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 02 October 2023

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MO3C05

Canadian Light Source Beam Position Visualization Tool

24

M. Bree, T. Batten, C.W. Stevens, J.M. Vogt
CLS, Saskatoon, Saskatchewan, Canada

The CLS Orbit Correction (OC) system acquires, collates, and publishes storage ring beam centroid position information from 48 beam position monitors (BPMs) at a rate of 1000 samples per second. We present a "Storage Ring Beam Position Visualization Tool" that computes and displays dynamic Fast Fourier Transforms (FFTs) and Cumulative Power Spectral Densities (CPSDs) for all BPMs in real-time using full resolution data. The computed FFTs and CPSDs can be plotted in various combinations and in waterfall plots that allow visualization of changes over long periods of time. In addition, correlations between all BPM channel combinations are computed and ranked. Data from any two BPM channels can be selected for plotting in two dimensions wherein correlations are visually apparent. Computed CPSDs are further binned and published in scalar EPICS PVs which are archived for further analysis. Preliminary results from the Beam Position Visualization Tool have proven useful in characterizing beam position noise at the CLS.

Slides MO3C05 [197.014 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MO3C05

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Received ※ 17 July 2023 — Revised ※ 16 August 2023 — Accepted ※ 13 September 2023 — Issue date ※ 26 September 2023

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MOP013

Expansion of the MTCA Based Direct Sampling LLRF at MedAustron for Hadron Synchrotron Applications

63

M. Wolf, M. Cerv, C. Kurfürst, S. Myalski, M. Repovž, C. Schmitzer
EBG MedAustron, Wr. Neustadt, Austria
A. Bardorfer, B. Baričevič, P. Leban, P. Paglovec, M. Škabar
I-Tech, Solkan, Slovenia

The MedAustron Ion Therapy Centre is a synchrotron-based particle therapy facility located in Lower Austria, which delivers proton and carbon ion beams for cancer treatments. Currently the facility treats over 400 patients per year and is expected to double this number in the future. Six years since the start of clinical operation, MedAustron is experiencing end-of-life issues concerning the digital Low Level RF components in the injector and the synchrotron. Replacements for these applications are under development and the chosen hardware is suitable to also update multiple beam diagnostic devices in the facility. Main targets for updates are the Schottky monitors, which were never properly integrated into the MedAustron Control system and the position pickup measurement system, which currently does not support turn by turn measurements. Comparison measurements with other state of the art diagnostic devices are ongoing to demonstrate the capabilities of the generic hardware. Furthermore, these measurements should show the increased usability and diagnostic potential compared to the legacy devices.

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP013

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Received ※ 07 September 2023 — Revised ※ 09 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 16 September 2023

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MOP015

RF Calibration and Distribution devices for SPIRAL2 BPMs

C. Jamet, T. Andre, P. Legallois, S. Leloir, C. Potier de courcy
GANIL, Caen, France

In order to achieve the required measurement accuracy for the SPIRAL2 BPMs in positions, ellipticities and phases, new RF Calibration and Distribution devices were developed, tested and installed on the SPIRAL2 Facility in 2022. Accuracy measurements depends on gain and phase differences of the 4 BPM measurement channels. In order to compensate analogic differences, digital corrections are applied in function of the calibration results. One of the main objectives was to automate the different steps of the calibration process in order to reduce the calibration time and avoid cable connections and disconnections. The second objective was to distribute RF reference signals to all BPM electronics cards with the same amplitudes and phases. This document describes technical solutions and qualifications performed, explains the calibration process, corrections and results obtained.

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MOP018

Beam-diagnostic and T0 System for the mCBM and CBM Experiments at GSI and FAIR

66

A. Rost, A. Senger
FAIR, Darmstadt, Germany
T. Galatyuk, M. Kis, J. Pietraszko, J. Thaufelder, F. Ulrich-Pur
GSI, Darmstadt, Germany
T. Galatyuk, V. Kedych, W. Krüger
TU Darmstadt, Darmstadt, Germany

Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 871072.
The Compressed Baryonic Matter (CBM) experiment at the Facility for Antiproton and Ion Research (FAIR) in Darmstadt requires a highly accurate beam monitoring and time-zero (T0) system. This system needs to meet the requirements of the CBM time-of-flight (ToF) measurement system for both proton and heavy ion beams, while also serving as part of the fast beam abort system. To achieve these goals, a detector based on chemical vapor deposition (CVD) diamond technology has been proposed. In addition, new developments using Low Gain Avalanche Detectors (LGADs) are currently under evaluation. This contribution presents the current development status of the beam detector concept for the CBM experiment.

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP018

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Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 30 September 2023

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MOP019

First Test with MicroTCA Based Cavity BPM Electronics for the European XFEL and FLASH

70

B. Lorbeer, H.T. Duhme, I. Krouptchenkov, T. Lensch, D. Lipka, M. Werner
DESY, Hamburg, Germany

The European X-ray free-electron laser (E-XFEL) and the FLASH2020+ project for the free electron laser Hamburg (FLASH) at DESY in Hamburg, Germany foresee several machine upgrades in the years to come. At FLASH a whole undulator section in a shutdown starting in summer 2024 and finishing in autumn 2025 is going to be rebuild. Existing button beam position monitors installed in this section of the machine do not deliver sufficient signal strength for future required resolution specification and orbit feedback optimization for machine operation. The resolution limitations will be overcome by replacing the button-based beam position monitors with in-house developed cavity beam position monitors and compact microTCA based radio frequency receiver read-out electronics. The measurement system has been tested and evaluated in a test setup at FLASH.

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP019

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Received ※ 05 September 2023 — Revised ※ 08 September 2023 — Accepted ※ 21 September 2023 — Issue date ※ 30 September 2023

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MOP021

New Beam Position Monitor System for PETRA IV

J.L. Lamaack
University of Hamburg, Hamburg, Germany
A. Bardorfer, L. Bogataj, M. Cargnelutti, P. Leban, M.O. Oblak, P. Paglovec, B. Repič
I-Tech, Solkan, Slovenia
H.T. Duhme, G. Kube, F. Schmidt-Föhre, K. Wittenburg
DESY, Hamburg, Germany

The PETRA IV project at DESY aims to upgrade the present synchrotron radiation source PETRA III into a source of ultra-low emittance with target emittance of 20 pmrad. The small beam emittance translates directly into much smaller beam sizes of about 7 microns horizontally and 3 microns vertically at insertion device source points, thus imposing stringent requirements on the machine’s stability. In order to measure beam position and control orbit stability to the required level of accuracy, a high-resolution BPM system consisting of 790 individual monitors will be installed. Its readout electronics will be based on MTCA.4 as a technical platform. To fulfill the long-term drift requirement (< 1 micron over 7 days), the concept of crossbar-switching was extended in such a way that the RF switch matrix is separated from the readout electronics and placed as close to the BPM pickup as possible, therefore enabling additional stabilization of the RF cables. At present, a fully populated MTCA.4 crate with 6 AMC boards for the readout of 12 BPMs is installed at PETRA III and extensively tested. This contribution summarizes the latest measurements of the long term stability.

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MOP022

Replacement of the Single-Pass BPM System with MicroTCA.4-based Versatile Electronics at SPring-8

74

H. Maesaka, N. Hosoda, S. Takano
RIKEN SPring-8 Center, Hyogo, Japan
H. Dewa, T. Fujita, N. Hosoda, H. Maesaka, M. Masaki, S. Takano
JASRI, Hyogo, Japan

We have developed MicroTCA.4-based versatile BPM readout electronics for the SPring-8 upgrade project, SPring-8-II (*). The input signals are processed by an rf front-end rear transition module (RTM) with band-pass filters, amplifiers, and step attenuators and digitized by 16-bit 370 MSPS high-speed digitizers on an advanced mezzanine card (AMC). The field-programmable gate array (FPGA) on the AMC calculates both single-pass and COD beam positions. The current BPM system at SPring-8 consists of approximately twenty single-pass dedicated BPMs and over two hundred other COD dedicated ones. In advance of SPring-8-II, so far, we renewed half of the single-pass dedicated BPM electronics to the MicroTCA.4. A graphical user interface (GUI) for the new BPM system was also developed and ready for tuning. The single-pass BPM resolution was confirmed to be better than 100 um for a 100 pC single bunch, sufficient for SPring-8-II. The other existing single-pass BPM electronics will also be renewed this summer. The full renewal of remaining COD dedicated BPM electronics to the versatile MicroTCA.4 ones is planned in the subsequent years before the construction of SPring-8-II.
(*) H. Maesaka et al., "Development of MTCA.4-based BPM Electronics for SPring-8 Upgrade", Proc. IBIC’19, doi:10.18429/JACoW-IBIC2019-WEBO03

Poster MOP022 [1.074 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP022

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Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 30 September 2023

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MOP023

The Conceptual Design Study for New BPM Signal Processing System of J-PARC (MR)

78

K. Satou, T. Toyama, S. Yamada
KEK, Tokai, Ibaraki, Japan

The BPM signal processing system, which is19 years old system, have been suffering from gain fluctuation due to contact resistance of the mechanical gain selector, communication disruption caused by an unstable contact of a card edge connector. In addition, it has a difficulty of repairments because some on-board parts have already reached end of product-life cycle, and some units have been in unusable situation. Presently, we are on the beam power upgrade campaign to 1.3 MW by increasing beam bunch current and shortening the MR operation cycle, and precise beam tunings would require massive waveform data processing and transfer to a storage than the present system. For this, we have been developing the system based on the 10 GbE optical link. The ADC board which is under development would perform direct sampling using the third harmonic of RF. The digital IQ demodulation technique is used to extract the baseband oscillation from the raw data. The obtained raw waveform as well as closed orbit data would be stored in the data storage system. In the presentation, we will report on the progress of development aimed at operation in 2025 and the conceptual design of the new system.

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP023

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Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 19 September 2023

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MOP024

The Design and Optimization of Digital Beam Position Monitor Processor in HEPS

Y.Y. Du, J.S. Cao, Z. Liu, Y.F. Sui, S.J. Wei, Q. Ye, J.H. Yue
IHEP, Beijing, People’s Republic of China

The Digital Beam Position Monitor (DBPM) is an important component of the High Energy Photon Source (HEPS). This article mainly introduces the design and development of the digital beam position measurement system based on the main indicators of HEPS, including the overall architecture design of the system, digital electronics design, RF electronics design, and the exposition of core algorithm design. It also provides a detailed performance comparison between the two versions of electronic design before and after optimization, including performance indicators such as flow-dependent, long-term stability, and position resolution. In laboratory testing, under the condition of an input signal of 499.8MHz and K factor is 8.26, the position resolution per turn by turn (TBT) is less than 1um, the fast orbit position resolution (FA) is less than 100nm, and the closed orbit position resolution (SA) is less than 10nm. The beam current-dependence and long-term stability are significantly better than the previous version, and the test results meet the design requirements of the High Energy Photon Source.

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MOP026

A Novel BPM Mechanical Center Calibration Method Based on Laser Ranging

82

X.H. Tang, J.S. Cao, Y.Y. Du, J. He, Y.F. Sui, J.H. Yue
IHEP, Beijing, People’s Republic of China

Determining the mechanical center of the beam position monitor(BPM) has been a difficulty for BPM calibration. To solve this problem, a method of positioning the BPM mechanical center based on laser ranging is proposed. This method uses high-precision antenna support as the core locating datum, and high-precision laser ranging sensors(LRSs) as the detection tool. By detecting the distances from the LRSs to the antenna support and the distances from the LRSs to the BPM, the mechanical center of the BPM can be indirectly determined. The theoretical system error of this method is within 20¿m, and the experimental results show that the measurement repeatability is less than 40¿m, This method has low cost and fast speed, which can be used for large-scale calibration.

Poster MOP026 [1.142 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP026

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Received ※ 13 July 2023 — Revised ※ 07 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 26 September 2023

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MOP028

The Design of Button Beam Position Monitor for Shenzhen Innovation Light-Source Facility

T. Yu
IASF, Shenzhen, Guangdong, People’s Republic of China

Shenzhen Innovation Light-source Facility (SILF) is a brand new project supported by the Chinese government to build a 4th generation synchrotron radiation source whose storage ring is so-called diffraction-limited. The beam design is that the emission is less than 100 pm·rad, and the beam instability is less than 10% of the beam spot. Therefore, the revolution of the beam position monitor (BPM) needs to be less than 0.12 ¿m for closed orbit detection. In order to achieve such excellent resolution, the signal-to-noise ratio of the BPM output signal in the 10MHz bandwidth is required to be better than 66dB. After the finite element numerical analysis, the diameter of the pickup electrode will be 8mm, and the gap between the electrode and the vacuum chamber will be 0.3 mm.

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MOP029

A Novel Design of a Dielectric-filled Cavity BPM for HUST-PTF

J.Q. Li, K. Fan, J. Wang
HUST, Wuhan, People’s Republic of China

To guarantee proton therapy safety and effectivity, non-invasive beam diagnostic¿NBD¿ devices are mandatory to precisely monitor the beam parameters during patient treatment. However, the clinical proton beams have characters of low currents and frequencies, which impose challenges for the design to improve the diagnosis resolution. A dielectric-filled racetrack cavity-type BPM has been studied deeply to compact its size while maintaining high diagnosis sensitivity. Moreover, the cross-talk between X and Y directions is effectively suppressed to ensure the diagnosis precision. The simulation and calculation results show that the cavity BPM has sufficient position sensitivity and signal-to-noise ratio. The signal-to-noise ratio can ba as large as 16.2 even when the beam intensity is 0.35 nA. The design studies results show that the dielectric-filled racetrack cavity is a potential candidate for a non-destructive beam position detector in HUST-PTF.

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MOP030

Developments of 4GSR BPM Electronics

87

S.W. Jang, G. Hahn, J.Y. Huang, C. Kim, D. Kim, G. Kim, B.K. Shin, D.C. Shin, D. Song
PAL, Pohang, Republic of Korea
W.J. Song
POSTECH, Pohang, Republic of Korea

The emittance of the 4th-generation storage ring (4GSR) to be constructed in Cheongju-Ochang, Korea, is expected to be approximately 100 times smaller than the existing 3rd-generation storage ring. With the decrease in emittance, more precise beam stabilization is required. To meet this requirement, the resolution of the beam position monitor (BPM) system also needs to be further improved. We have conducted research and development on the electronics of the BPM system for the 4GSR storage ring. In order to perform fast orbit feedback in the 4GSR storage ring, we need to acquire turn-by-turn beam position data, with a desired beam position resolution of 1 ¿m. Additionally, prototypes of the bunch-by-bunch monitoring system are being developed for the transverse feedback system and longitudinal feedback system. The internally developed electronics are intended to be modified for future use as monitors for multi-bunch beam energy measurements at the end of the linear accelerator, by adjusting the logic accordingly. In this presentation, we will describe more details of the current status of the development of the beam position monitor electronics for the 4GSR in Korea.

Poster MOP030 [24.607 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP030

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Received ※ 05 September 2023 — Revised ※ 11 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 19 September 2023

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MOP031

A Study Into the Long-Term Stability of Front End X-Ray Beam Position Monitor Support Columns at Diamond Light Source

90

C.E. Houghton, C. Bloomer, L. Bobb, D. Crivelli, J.E. Melton, H. Patel
DLS, Harwell, United Kingdom

Sand-filled steel columns are used at Diamond Light Source to support front end X-ray beam position monitors. This approach is chosen due to the relatively large thermal mass of the sand being considered useful to reduce the rate at which expansion and contraction of the column occurred as the storage ring tunnel temperature varied, particularly during machine start-up. With the higher requirements for mechanical stability for the upcoming Diamond-II upgrade, there is now a need to assess and quantify the current system’s impact on X-ray beam movement. A study of thermal and mechanical stability has been carried out to quantify the stability performance of the front end X-ray beam position monitor’s columns and the impact that column motion may have on the X-ray beam position measurement. Measurements have been made over a range of different timescales, from 250 Hz up to 2 weeks. The measured stability of the support column is presented, showing that it meets our Diamond-II stability requirements. A comparison of the stability of the column with and without a sand filling is presented.

Poster MOP031 [0.594 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP031

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Received ※ 06 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 17 September 2023

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MOP032

One Dimensional Beam Position Monitor Prototype using Incoherent Cherenkov Diffraction Radiation

94

A.J. Clapp
Royal Holloway, University of London, Surrey, United Kingdom
L. Bobb, G. Cook
DLS, Oxfordshire, United Kingdom
P. Karataev
JAI, Egham, Surrey, United Kingdom

This paper proposes a novel advancement in both the studies of Cherenkov diffraction radiation (ChDR) and beam instrumentation. The proposed beam position monitor (BPM) consists of two identical fused Silica prism radiators, with a fibre collimator attached to each one, which in turn are connected to a photodetector via a series of optical fibres. The setup will be implemented into the booster to storage ring transfer line at Diamond Light Source ¿ an electron light source with 3 GeV beam energy. The prototype proposed aims to test the feasibility of a full BPM utilising ChDR. If proven to be fully realisable, optical rather than capacitive BPM pickups could be more widely distributed. The paper will include the complete design and preliminary results of a one-dimensional BPM, utilising the ChDR effect.

Poster MOP032 [2.516 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP032

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Received ※ 26 August 2023 — Revised ※ 07 September 2023 — Accepted ※ 14 September 2023 — Issue date ※ 27 September 2023

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MOP033

1L Target Harp Diagnostic Display Tool

99

A.D. Walker, E.L. Kerstiens
LANL, Los Alamos, New Mexico, USA

The Los Alamos Neutron Science Center (LANSCE) completed upgrades to its 1L Target Facility, which included installing the new Mark IV target assembly. This added a third tungsten target located upstream of the other two targets. Prior to Mark IV, beam centering on target was achieved by using thermocouples mounted to the quadrants and center of the upper target coolant chamber. It is slightly offset from center of the old upper target and it shadows several of the thermocouples previously used to center beam on target. This required adjustments to the diagnostic tools utilized to monitor position of the H⁻ beam that is being delivered to the 1L target. The original display included the thermocouple readouts and displayed a visual beam profile and position taken from an upstream harp. With some of the thermocouples now being shadowed, an image overlay was added to show where the harp¿s measured beam position is relative to both the upper and middle targets. This gives the beam operations team an additional level of awareness when it comes to thermocouple temperatures, beam steering, and beam tuning. Details of the display tool and its associated upgrades are presented.
LANL Report #: LA-UR-23-25004

Poster MOP033 [0.825 MB]

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reference for this paper ※ doi:10.18429/JACoW-IBIC2023-MOP033

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Received ※ 05 September 2023 — Revised ※ 07 September 2023 — Accepted ※ 13 September 2023 — Issue date ※ 20 September 2023

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