Keyword: synchrotron
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MOCO03 Estimation of Longitudinal Profiles of Ion Bunches in the LHC Using Schottky-Based Diagnostics distributed, experiment, diagnostics, hadron 44
 
  • K. Łasocha, D. Alves
    CERN, Meyrin, Switzerland
 
  The Large Hadron Collider (LHC) Schottky monitors have been designed to measure various parameters of relevance to beam quality, namely tune, momentum spread and chromaticity. We present another application of this instrument - the evaluation of longitudinal bunch profiles. The relation between the distribution of synchrotron amplitudes within the bunch population and the longitudinal bunch profile is derived from probabilistic principles. Our approach, limited to bunched beams with no intra-bunch coherent motion, initially fits the cumulative power spectral density of acquired Schottky spectra with the underlying distribution of synchrotron amplitudes. The result of this fit is then used to reconstruct the bunch profile using the derived model. The results obtained are verified by a comparison with measurements from the LHC Wall Current Monitors.  
slides icon Slides MOCO03 [48.066 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOCO03  
About • paper received ※ 04 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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MOPP027 First Beam-based Test of Fast Closed Orbit Feedback System at GSI SIS18 controls, closed-orbit, acceleration, feedback 153
 
  • R. Singh, A. Doring, P. Forck, K. Lang, S.H. Mirza, D. Rodomonti, D. Schupp, M. Schwickert, H. Welker
    GSI, Darmstadt, Germany
  • A. Bardorfer
    I-Tech, Solkan, Slovenia
 
  Funding: European Unions Horizon 2020 Research and Innovation programme under Grant Agreement No. 730871 (ARIES). German Academic Exchange Service under Personal Reference No. 91605207.
The SIS18 synchrotron of GSI will be used as a booster ring for the SIS100 synchrotron built in the scope of the FAIR project. In order to preserve the beam quality during the whole acceleration ramp, a new closed orbit feedback (COFB) system is implemented at the SIS18 which operates with the existing BPMs and steerer magnets. The system aims for a bandwidth of several 100 Hz and robustness against the variation of the response matrix and the beam rigidity during the ramp. The architecture of the system and the results of the first beam-based test of the COFB hardware are presented. As a first step, the orbit correction is performed over the entire ramp using the response matrix corresponding to injection energy only taking the beam rigidity into account. Experimental observations of the bandwidth limitations arising from the temporal delay of the steerer power supplies and the spatial model variation during the ramp are compared with simulations. It is found that the temporal and the spatial model mismatch have similar effect on the achievable bandwidth of the COFB.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP027  
About • paper received ※ 07 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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MOPP030 Preliminary Test of XBPM Local Feedback in TPS feedback, electron, photon, operation 162
 
  • P.C. Chiu, J.-Y. Chuang, K.T. Hsu, K.H. Hu, C.H. Huang
    NSRRC, Hsinchu, Taiwan
 
  TPS is 3-GeV synchrotron light source which have opened for public users since September 2016 and now offers 400 mA top-up mode operation. The requirements of the long term orbit stability have been gradually more and more stringent. The report investigates the long-term orbit stability improved by applying local XBPM feedback.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP030  
About • paper received ※ 02 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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MOPP031 Optimisation of the ISIS Proton Synchrotron Experimental Damping System damping, kicker, betatron, feedback 166
 
  • A. Pertica, D.W. Posthuma de Boer, R.E. Williamson
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
  • J. Komppula
    CERN, Meyrin, Switzerland
 
  The ISIS Neutron and Muon Source, located in the UK, consists of a H linear accelerator, a rapid cycling proton synchrotron and two extraction lines delivering protons onto heavy metal targets. One of the limiting factors for achieving higher intensities in the accelerator is the head-tail instability present in the synchrotron, around 2ms after injection. In order to mitigate this instability, an experimental damping system is being developed for the ISIS synchrotron. Initial tests using a split electrode BPM as a pickup and a ferrite loaded kicker as a damper showed positive results. This paper describes the different developments made to the damping system and planned improvements to optimize its performance for use in normal operations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP031  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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MOPP032 Fast Feedback Using Electron Beam Steering to Maintain the X-Ray Beam Position at a Monochromatic X-Ray Diagnostic at Diamond Light Source feedback, electron, power-supply, controls 171
 
  • C. Bloomer, G. Rehm, A. Tipper
    DLS, Oxfordshire, United Kingdom
 
  A new feedback system is being developed at Diamond Light Source, applying a modulation to the position of the electron beam to keep the synchrotron X-ray beam fixed at the sample-point. Beamline detectors operating in the 100-1000Hz regime are becoming common, and the X-ray beam stability demanded by beamlines is thus of comparable bandwidths. In this paper we present a feedback system operating at these bandwidths, using a diagnostic instrument permanently installed in the X-ray beam path to measure the error in beam position at the sample point, and fast air-cored magnets to apply a small modulation to the electron beam to compensate. Four magnets are used to generate electron beam bumps through an ID straight. This modulation of the beam away from the nominal orbit is small, less than 10 microns, but should be sufficient to compensate for the bulk of the X-ray motion observed at the sample. It is small enough that the impact on the machine will be negligible. This system aims to maintain X-ray beam stability to within 3% of a beam size, at bandwidths of up to 500Hz.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP032  
About • paper received ※ 09 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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MOPP045 MAX IV Operations - Diagnostic Tools and Lessons Learned storage-ring, operation, status, injection 210
 
  • B. Meirose, V. Abelin, B.E. Bolling, M. Brandin, R. Høier, A. Johansson, P. Lilja, J.S. Lundquist, S. Molloy, F. Persson, J.E. Petersson, R. Svärd
    MAX IV Laboratory, Lund University, Lund, Sweden
 
  In this contribution, I present some of the new beam diagnostic and monitoring tools developed by the MAX IV Operations Group. In particular, new BPM and accelerator tunes visualization tools and other simple but useful applications we have developed, such as our RF System Monitor, are presented. I also briefly share our experience with the development of audible alarms, which help operators monitor various parameters of the machine and explain how the implementation of all these tools have improved accelerator operations at MAX IV.  
poster icon Poster MOPP045 [2.879 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-MOPP045  
About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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TUPP017 Thermal Performance of Diamond SR Extraction Mirrors for SuperKEKB extraction, MMI, optics, electron 327
 
  • J.W. Flanagan, M. Arinaga, H. Fukuma, H. Ikeda, G. Mitsuka, Y. Suetsugu
    KEK, Ibaraki, Japan
  • E. Mulyani
    BATAN, Yogyakarta, Indonesia
  • E. Mulyani
    Sokendai, Ibaraki, Japan
 
  The SuperKEKB accelerator is a high-current, low-emittance upgrade to the KEKB double ring collider. The beryllium extraction mirrors used for the synchrotron radiation (SR) monitors at KEKB suffered from heat distortion due to incident SR, leading to systematic changes in magnification with beam current, and necessitating continuous monitoring and compensation of such distortions in order to correctly measure the beam sizes.* To minimize such mirror distortions, quasi-monocrystalline CVD diamond mirrors have been designed and installed at SuperKEKB.** Diamond has a very high heat conductance and a low thermal expansion coefficient. With such mirrors it is hoped to reduce the beam current-dependent magnification to the level of a few percent at SuperKEKB. Preliminary measurements of mirror distortion during SuperKEKB commissioning show very promising results with regard to thermal performance, though full beam currents have not yet been stored in the SuperKEKB rings. Measurements of the thermal deformation of the diamond mirrors will be presented in this paper, along with a description of the design of the mirrors and their mounts, and issues encountered during commissioning.
*M. Arinaga et al., NIM, A499, p. 100 (2003).
**J.W. Flanagan et al., "Diamond mirrors for the SuperKEKB synchrotron radiation monitors," Proc. IBIC2012, Tsukuba, Japan p. 515 (2012).
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP017  
About • paper received ※ 09 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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TUPP026 Diagnostic Beamlines at the Solaris Storage Ring diagnostics, storage-ring, emittance, electron 361
 
  • A. Kisiel, S. Cabala, A.M. Marendziak, M. Ptaszkiewicz, A.I. Wawrzyniak, I.S. Zadworny, Z. Zbylut
    Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
 
  Precise measurement and control of the particle beam emittance is a very important input to characterize the performance of any accelerator/SRS. Beam characterizations at the SOLARIS National Synchrotron Radiation Centre are provided by two independent diagnostic beamlines called the X-ray synchrotron radiation (PINHOLE) and optical synchrotron radiation (LUMOS) beamlines, respectively. The PINHOLE beamline depicts the electron beam by analyzing the emitted X-rays. However this method is predominantly applied to the middle and high energy storage rings. At Solaris storage ring with the nominal energy of 1.5 GeV and critical photon beam energy of c.a. 2 keV, the design of the beamline was modified to provide sufficient X-ray photon flux for proper imaging. Second diagnostic beamline LUMOS will be installed and commissioned in next few months. Issues discussed include the general design philosophy, choice of instrumentation, limits to resolution, and actual performance.
*e-mail: adriana.wawrzyniak@uj.edu.pl
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP026  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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TUPP031 Electron Beam Size Measurements Using the Heterodyne Near Field Speckles at ALBA radiation, experiment, synchrotron-radiation, scattering 378
 
  • M. Siano, M.A.C. Potenza
    Universita’ degli Studi di Milano & INFN, Milano, Italy
  • U. Iriso, C.S. Kamma-Lorger, A.A. Nosych
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • S. Mazzoni, G. Trad
    CERN, Geneva, Switzerland
  • B. Paroli
    Universita’ degli Studi di Milano, Milano, Italy
 
  Experiments using the heterodyne near field speckle method (HNFS) have been performed at ALBA to characterize the spatial coherence of the synchrotron radiation, with the ultimate goal of measuring both the horizontal and vertical electron beam sizes. The HNFS technique consists on the analysis of the interference between the radiation scattered by a colloidal suspension of nanoparticles and the synchrotron radiation, which in this case corresponds to the hard x-rays (12keV) produced by the in-vacuum undulator of the NCD-Sweet beamline. This paper describes the fundamentals of the technique, possible limitations, and shows the first experimental results changing the beam coupling of the storage ring.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP031  
About • paper received ※ 06 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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TUPP034 Analysis of Quadrupolar Measurements for Beam Size Determination in the LHC emittance, electron, electronics, pick-up 392
 
  • D. Alves, M. Gąsior, T. Lefèvre
    CERN, Meyrin, Switzerland
 
  Due to limitations with non-invasive beam size diagnostics in the LHC, particularly during the energy ramp, there has been an interest to explore quadrupolar-based measurements for estimating the transverse beam size, and hence determining the transverse emittance. This technique is especially attractive as it is completely passive and can use the existing beam position instrumentation. In this work, we perform an analysis of this method and present recent measurements taken during energy ramps. Quadrupolar-based measurements are compared with wire-scanner measurements and a calibration strategy is proposed to overcome present limitations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP034  
About • paper received ※ 03 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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TUPP036 Performance of an In-Air Secondary Emission Grid Profile Monitor at the ISIS Neutron and Muon Source target, focusing, simulation, neutron 402
 
  • D.W. Posthuma de Boer, C. Bovo, H.V. Cavanagh, B. Jones, A.H. Kershaw, A. Pertica
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  The ISIS neutron and muon source, located in the UK, consists of an H linear accelerator, a rapid cycling proton synchrotron and extraction lines to two target stations. A project is currently under way to replace the target assembly of the First Target Station (TS1) in order to secure its continued operation and improve operational flexibility. In addition to a number of other diagnostic tools, a new secondary emission (SEM) grid profile monitor is expected to be located within the helium atmosphere of the new target assembly. To investigate the performance of an out-of-vacuum SEM grid, a prototype monitor was positioned in-air between a beam exit window and a dump. Profile measurements taken with this monitor are presented, including tests at a range of bias voltages with a fast data acquisition system to investigate secondary signal sources.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP036  
About • paper received ※ 04 September 2019       paper accepted ※ 07 September 2019       issue date ※ 10 November 2019  
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TUPP038 Spatial Resolution of an X-ray Pinhole Camera using a Multi-layer Monochromator photon, emittance, simulation, storage-ring 412
 
  • L. Bobb, G. Rehm
    DLS, Oxfordshire, United Kingdom
 
  X-ray pinhole cameras are widely used for beam emittance monitoring at synchrotron light sources. Due to the reduction in beam emittance expected for the many fourth generation machine upgrades, the spatial resolution of the pinhole camera must be improved accordingly. It is well known that there are many contributions to the point spread function. However, a significant contribution arises from diffraction by the pinhole aperture. Given that diffraction is dependent on the spectral distribution of the incident synchrotron radiation, the spatial resolution can be improved by using a monochromatic beam. For optimal performance, the photon energy should be matched to the pinhole aperture size. Here we investigate the spatial resolution of the pinhole camera as a function of photon energy using a multi-layer monochromator.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP038  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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TUPP039 Horizontal and Vertical Emittance Measurements of the Advanced Photon Source Booster Synchrotron Beam at High Charge emittance, quadrupole, electron, booster 415
 
  • K.P. Wootton, W. Berg, J.R. Calvey, K.C. Harkay, A.H. Lumpkin, A. Xiao, B.X. Yang, C. Yao
    ANL, Lemont, Illinois, USA
 
  Funding: This research used resources of the Advanced Photon Source, operated for the U.S. Department of Energy Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.
In order to maximise the injection efficiency from the booster synchrotron into the proposed Advanced Photon Source Upgrade storage ring, beam-based optimisation of the booster electron optical lattice is anticipated. In the present work, we present non-destructive beam size and emittance measurements using the booster synchrotron light monitor and destructive quadrupole scan emittance measurements in the booster to storage ring transport line. Destructive measurements are performed with a 0.1 mm thickness Cerium-doped Yttrium Aluminium Garnet screen. In order to characterise performance, both the beam energy at extraction (5, 6 and 7 GeV) and the bunch charge are varied.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP039  
About • paper received ※ 04 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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TUPP044 Multiple Synchrotron Light Monitors for Transverse Matching and Monitoring at CEBAF emittance, quadrupole, radiation, software 436
 
  • B.G. Freeman, J. Gubeli, M.G. Tiefenback
    JLab, Newport News, Virginia, USA
 
  Funding: DOE Contract No. DE-AC05-06OR23177
Beam setup at the Continuous Electron Beam Accelerator Facility (CEBAF) involves threading beam through the machine, monitoring global transfer functions to identify and address cumulative lattice errors. Transverse beam emittance may grow by as much as two orders of magnitude, mediated by synchrotron radiation. Re-matching the enlarged beam phase space into successive re-circulation arcs minimizes this emittance growth but requires knowledge of the actual beam distribution. This is now accomplished through quadrupole scans using wire profile monitors, the most time-consuming activity in our setup process. We propose to use Synchrotron Light Monitors (SLMs) to image the beam at homologous points in the four super-period recirculation arc lattices. Benefits include real-time monitoring of beam parameters and reduced elapsed time for initial setup. These SLMs will be installed in Arc 7 of the CEBAF machine, where Synchrotron Radiation contributes moderately to emittance growth. One of four required SLMs will be installed and commissioned this year, with the rest being installed next year.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-TUPP044  
About • paper received ※ 04 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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WECO03 Tune Computation via Model Fitting to Swept Machine Response Measurement feedback, operation, betatron, resonance 482
 
  • M.G. Abbott, G. Rehm
    DLS, Oxfordshire, United Kingdom
 
  At Diamond Light Source we compute the horizontal and vertical tunes by fitting a simple multi-pole resonator model to the measured electron beam frequency response. The transverse (and longitudinal) tune response is measured by sweeping an excitation across the range of possible tune frequencies and synchronously measuring the IQ response. The multi-pole resonator model is a good fit to the measured behaviour, but the fitting process is surprisingly challenging. Problems include noisy measurements, very complex beam responses in the presence of increasing chromaticity, poor data when the beam is close to instability, and a number of challenges with the stability of the algorithm. The tune fitting algorithm now in use at Diamond has been developed and refined over many years. It is finally stable enough to work reliably throughout most beam operating conditions. The algorithm involves alternating peak finding and non-linear fitting, with a fairly naive mathematical approach; the main focus is on providing reliable results.  
slides icon Slides WECO03 [1.059 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WECO03  
About • paper received ※ 04 September 2019       paper accepted ※ 09 September 2019       issue date ※ 10 November 2019  
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WEPP003 A new button-type beam position monitor for BESSY II and BESSY VSR impedance, vacuum, operation, storage-ring 500
 
  • J.G. Hwang, V. Dürr, F. Falkenstern, M. Ries, A. Schälicke, G. Schiwietz, D. Wolk
    HZB, Berlin, Germany
 
  Funding: This work was supported by the German Bundesministerium für Bildung und Forschung, Land Berlin and grants of Helmholtz Association.
The future BESSY VSR system involves more than one order-of-magnitude differences in the total charge of adjacent short and long bunches within the bunch train. Thus, any signal ringing beyond a nanosecond in time will cause a misreading of beam position and current, specifically for low bunch charges. This calls for improved performance for the bunch-selective operation of the beam-position-monitor (BPM) system. We report on the corresponding design and fabrication of a new button BPM with advanced features, such as impedance matching inside the button as well as optimization of insulator material, button size, and position, for reduced crosstalk between buttons.
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP003  
About • paper received ※ 04 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP007 Calibration for Beam Energy Position Monitor System for Riken Superconducting Acceleration Cavity network, linac, cyclotron, impedance 519
 
  • T. Watanabe, M. Fujimaki, N. Fukunishi, H. Imao, O. Kamigaito, N. Sakamoto, Y. Watanabe, K. Yamada
    RIKEN Nishina Center, Wako, Japan
  • K. Hanamura, T. Kawachi
    Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
  • A. Kamoshida
    National Instruments Japan Corporation, MInato-ku, Tokyo, Japan
  • R. Koyama
    SHI Accelerator Service Ltd., Tokyo, Japan
  • A. Miura
    JAEA/J-PARC, Tokai-mura, Japan
  • T. Miyao, T. Toyama
    KEK, Ibaraki, Japan
 
  Upgrades for the RIKEN Heavy-ion Linac (RILAC) involving a new Superconducting Linac (SRILAC) are currently underway to promote super-heavy element searches and Radio Isotope (RI) production (211At) for medical use at the RIKEN radioactive isotope beam factory (RIBF). If destructive monitors are used, since they generate outgassing, it becomes difficult to maintain the Q value and surface resistance indicating the performance of the superconducting radio frequency (SRF) cavities over a long period of time. Therefore it is crucially important to develop nondestructive beam measurement diagnostics. We have developed a beam energy position monitor (BEPM) system which can measure not only the beam position but also the beam energy simultaneously by measuring the time of flight of the beam. By using parabolic cut, ideal linear response of the quadrupole moments is realized, keeping a good linear position sensitivity at the same time. We fabricated 11 BEPMs and the position calibration system employing a wire method has been used to obtain the sensitivity and offset of BEPMs. We will describe details concerning the BEPM, calibration system and measured results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP007  
About • paper received ※ 05 September 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP016 Real-Time Synchronized Calibration and Computing System with EPICS Based Distributed Controls in the TPS XBPM System controls, EPICS, photon, distributed 541
 
  • J.-Y. Chuang, C.K. Chan, C.-C. Chang, C.M. Cheng, Y.T. Cheng, Y.M. Hsiao, Y.Z. Lin, Y.-C. Liu, C. Shueh, Y.C. Yang
    NSRRC, Hsinchu, Taiwan
 
  In synchrotron facilities, X-ray beam position monitor (XBPM) is an important detector for photon beam position monitoring and must be calibrated to ensure reliability and precision. However, light source operating conditions, such as beam orbit, injection and insertion device parameters, etc., can influence the sensitivity and specific weighting of photoemission current from the XBPM diamond blades. In the Taiwan Photon Source (TPS), Experimental Physics and Industrial Control System (EPICS) was utilized to implant an automatic calibration process. By using EPICS, we can ensure a seamless integration between the different front ends (FEs) and direct all data stream into a centralized server, creating a distributed XBPM calibration system. The XBPM performance indicators are analyzed to evaluate the validity of calibration parameters by input/ output controller (IOC) in each FE computing system. This paper will discuss the benefits of implanting this distributed control system into a working environment such as the TPS.
XBPM, TPS, Front end, Distributed XBPM calibration system
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP016  
About • paper received ※ 01 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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WEPP021 Machine Learning Image Processing Technology Application in Bunch Longitudinal Phase Data Information Extraction network, damping, injection, SRF 561
 
  • X.Y. Xu, Y.M. Zhou
    SINAP, Shanghai, People’s Republic of China
  • Y.B. Leng, Y.M. Zhou
    SSRF, Shanghai, People’s Republic of China
  • X.Y. Xu
    University of Chinese Academy of Sciences, Beijing, People’s Republic of China
 
  To achieve the bunch-by-bunch longitudinal phase measurement, Shanghai Synchrotron Radiation Facility (SSRF) has developed a high resolution measurement system. We used this measurement system to study the injection transient process, and obtained the longitudinal phase of the refilled bunch and the longitudinal phase of the original stored bunch. A large number of parameters of the synchronous damping oscillation are included in this large amount of longitudinal phase data, which are important for the evaluation of machine state and bunch stability. The multi-turn phase data of a multi-bunch is a large two-dimensional array that can be converted into an image. The convolutional neural network (CNN) is a machine learning model with strong capabilities in image processing. We hope to use the convolutional neural network to process the longitudinal phase two-dimensional array data, and extract important parameters such as the oscillation amplitude and the synchrotron damping time.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP021  
About • paper received ※ 23 August 2019       paper accepted ※ 10 September 2019       issue date ※ 10 November 2019  
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WEPP038 Observation of Microbunching Instabilities using THz Detector at NSLS-II detector, radiation, synchrotron-radiation, dipole 624
 
  • W.X. Cheng
    ANL, Lemont, Illinois, USA
  • B. Bacha, G.L. Carr
    BNL, Upton, Long Island, New York, USA
 
  Microbunching instabilities have been observed in several light sources with high single bunch current stored. The instability is typically associated with threshold beam currents. Energy spread and bunch length are increasing above the thresholds. Recently, a terahertz (THz) detector was installed at the cell 22 infrared (IR) beamline at NSLS-II storage ring to study the micro-bunch instabilities. The IR beamline has wide aperture allowing long-wavelength synchrotron radiation or microwave signal propagate to the end station, where the detector was installed. The detector output signal has been analyzed using oscilloscope, spectrum analyzer and FFT real-time spectrum analyzer. Clear sidebands appear as single bunch current increases and the sidebands tend to shift/jump. We present measurement results of the THz detector at different nominal bunch lengths and ID gaps.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-WEPP038  
About • paper received ※ 04 September 2019       paper accepted ※ 08 September 2019       issue date ※ 10 November 2019  
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THAO02 Towards Full Silicon 4H-SiC Based X-Ray Beam Monitoring feedback, storage-ring, monitoring, experiment 663
 
  • M. Camarda, M. Birri, M. Carulla, D. Grolimund, B. Meyer, C. Pradervand
    PSI, Villigen PSI, Switzerland
  • U. Grossner, S.M. Nida, A. Tsibizov, T. Ziemann
    ETH, Zurich, Switzerland
 
  In this work, we present extensive theoretical and experimental results of novel Silicon Carbide x-ray sensors for beam position monitoring (XBPM). Until recently, diamond, was considered the material-of-choice for continuous monitoring of hard (>6keV) x-ray beams at synchrotron light sources. Diamond XBPM are now commercially available as single crystal* and polycrystalline** sensors. However, in a recently published paper***, we have shown that Silicon Carbide is superior to both diamond crystal types in several critical aspects. Specifically, we found superior electrical characteristics (sensor dynamics, signal uniformity, signal strength) and superior optical properties (full device transparency, device active area, signal strength) when compared to commercial polycrystalline and single crystal diamond, respectively. We also succeeded in the ’industrialization’ of the SiC fabrication process, allowing for the simultaneous realization of several (>40) sensors in up to 4’ SiC wafers, with high yields. More recently we have also analyzed the fluorescence of SiC sensors as compared to YAG ones, finding that SiC can also be used for hybrid position/shape monitoring schema.
* CIVIDEC. AT, SYDORTECHNOLOGIES. COM
** DECTRIS. COM
*** S. Nida, et. al. Silicon carbide X-ray beam position monitors for synchrotron applications J. Synchrotron Rad. 26, 28-35 (2019)
 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IBIC2019-THAO02  
About • paper received ※ 11 September 2019       paper accepted ※ 11 September 2019       issue date ※ 10 November 2019  
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