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MOOB04 Upgrade of the Machine Protection System Toward 1.3 MW Operation of the J-PARC Neutrino Beamline proton, operation, FPGA, electron 18
  • K. Sakashita, M.L. Friend, K. Nakayoshi
    KEK, Ibaraki, Japan
  • Y. Koshio, S. Yamasu
    Okayama University, Faculty of Science, Okayama City, Japan
  The machine protection system (MPS) is one of the essential components to realize safe operation of the J-PARC neutrino beamline, where a high intensity neutrino beam for the T2K long baseline neutrino oscillation experiment is generated by striking 30GeV protons on a graphite target. The proton beam is extracted from the J-PARC main ring proton synchrotron (MR) into the primary beamline. The beamline is currently operated with 485kW MR beam power. The MR beam power is planned to be upgraded to 1.3+ MW. The neutrino production target could be damaged if the high intensity beam hits off-centered on the target, due to non-uniform thermal stress. Therefore, in order to protect the target, it is important to immediately stop the beam when the beam orbit is shifted. A new FPGA-based interlock module, with which the beam profile is calculated in real time, was recently developed and commissioned. This module reads out signals from a titanium-strip-based secondary emission profile monitor (SSEM) which is placed in the primary beamline. An overview of the upgrade plan of the MPS system and the results of an initial evaluation test of the new interlock module will be discussed.  
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MOPB07 Beam Parameter Measurements for the J-PARC High-Intensity Neutrino Extraction Beamline proton, radiation, monitoring, extraction 85
  • M.L. Friend
    KEK, Ibaraki, Japan
  Proton beam monitoring is absolutely essential for the J-PARC neutrino extraction beamline, where neutrinos are produced by the collision of 30 GeV protons from the J-PARC MR accelerator with a long carbon target. Continuous beam monitoring is crucial for the stable and safe operation of the extraction line high intensity proton beam, since even a single misfired beam spill can cause serious damage to beamline equipment at 2.5x1014 and higher protons-per-pulse. A precise understanding of the proton beam intensity and profile on the neutrino production target is also necessary for predicting the neutrino beam flux with high precision. Details of the suite of monitors used to continuously and precisely monitor the J-PARC neutrino extraction line proton beam will be shown, including recent running experiences, challenges, and future upgrade plans.  
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MOPC04 Beam Charge Measurement and System Calibration in CSNS proton, extraction, beam-transport, operation 122
  • W.L. Huang, F. Li
    CSNS, Guangdong Province, People's Republic of China
  • L. Ma, S. Wang, T.G. Xu
    IHEP, Beijing, People's Republic of China
  In China Spallation Neutron Source(CSNS), the beam charge monitors along the ring to the target beam transport line(RTBT) and the ring to the dump beam transport line(RDBT), are consisted of an ICT and three FCTs manufactured by Bergoz. The electronics includes a set of NI PXIe-5160 oscilloscope digitizer, and a Beam Charge Monitor(BCM) from Bergoz as supplementary. The beam charge monitors provide the following information: a) the quantity of protons bombarded the tungsten target; b) the efficiency of particle transportation; c) a T0 signal to the detectors and spectrometers of the white neutron source. With the calibration with an octopus 50Ω terminator in lab and an onboard 16-turn calibrating coils at the local control room, corrections for the introducing the 16-turn calibrating coils and the long cable were made. An accuracy of ±2% for the beam charge measurement during the machine operation has been achieved with the ICT/FCTs and a PXIe-5160 oscilloscope digitizer.  
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MOPC12 The Radial Detector in the Cyclotron of HIMM cyclotron, controls, detector, extraction 140
  • M. Li, Y.C. Chen, Y.C. Feng, X.C. Kang, S. Li, W.L. Li, W.N. Ma, R.S. Mao, Y.G. Nie, H.H. Song, Y. Wang, Y. Yin, T.C. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
  The cyclotron is designed as the injector of the Heavy Ion Medical Machine (HIMM) in Wuwei city, China. It provides 10 uA carbon beams to fulfill the requirement of the accumulation in the following syn-chrotron. The Radial detector is used to measure the beam current and beam turn motion in this Cyclotron. The beam current signal gathered by radial detector is acquired by four picoammeters, meanwhile the beam time structure is measured with FPGA and real time operating system. This paper introduces the design of radial detector, the motion control and data acquisition system for it of the cyclotron. Finally, the beam current and turn pattern measurement results at HIMM are presented in this paper.  
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TUPA07 Collimator for Beam Position Measurement and Beam Collimation for Cyclotron controls, cyclotron, vacuum, collimation 224
  • L.X. Hu, Y. Chen, K.Z. Ding, J. Li, Y. Song, Q. Yang
    ASIPP, Hefei, People's Republic of China
  • Y.C. Wu, K. Yao
    HFCIM, HeFei, People's Republic of China
  Funding: This work is supported in part by grants 1604b0602005 and 1503062029.
In order to restrict the beam dispersion and diffusion at the extraction area of the cyclotron and to detect abnormal beam loss, a beam collimator system has been designed to collimate the beam and to measure its transverse positions. The collimator system is composed of a vacuum cavity, two pairs of beam targets, a set of driving and supporting mechanism, and a measurement and control unit. The beam target with the size determined by the diameter of the beam pipe, the particle energy and beam intensity, will generate current signal during particle deposition. Each pair of beam targets has bilateral blocks which forms a slit in either horizontal or vertical direction. Servo motor and screw rod are used so that the target can reciprocate with the repeatability of less than 0.1mm. The measurement and control system based on LabVIEW can realize the motion control and current measurement of the targets and then calculate the beam transverse positions.
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WEPA17 Development, Fabrication and Laboratory Tests of Bunch Shape Monitors for ESS Linac electron, dipole, space-charge, quadrupole 407
  • S.A. Gavrilov, D.A. Chermoshentsev, A. Feschenko
    RAS/INR, Moscow, Russia
  Two Bunch Shape Monitors have been developed and fabricated in INR RAS for European Spallation Source linac. To fulfil the requirements of a 4 ps phase resolution the symmetric λ-type RF-deflector based on the parallel wire line with capacitive plates has been selected. Additional steering magnet to correct incline of the focused electron beam is also used. Limitations due to space charge of the analysed beam and due to external magnetic fields are discussed. The results of the laboratory tests of the monitors are presented.  
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WEPB02 Development of a a YAG/OTR Monitor photon, diagnostics, background, detector 429
  • R.J. Yang, P. Bambade, S. Wallon
    LAL, Orsay, France
  • A. Aryshev, T. Naito, N. Terunuma
    KEK, Ibaraki, Japan
  • M. Bergamaschi
    CERN, Geneva, Switzerland
  To study the mechanisms of beam halo formation and its dynamics, a YAG/OTR monitor has been developed and tested at the KEK-ATF. The monitor has four ceramic Ce:YAG screens for the visualization of the beam core and beam halo and an OTR target to provide complementary measurements of beam core. A high dynamic range (DNR>105) and a high resolution (<10 um) have been demonstrated through the optimization of light detection, reduction of background and suppression of scintillation saturation. Measurements using this monitor are consistent with previous results and theoretical modeling of beam halo at ATF, and have allowed further progress in the characterization of the driving mechanisms.  
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WEPB11 Spatial Resolution Improvement of OTR Monitors by Off-axis Light Collection radiation, electron, diagnostics, FEL 451
  • A. Potylitsyn, A.I. Novokshonov, L.G. Sukhikh
    TPU, Tomsk, Russia
  • G. Kube, A.I. Novokshonov
    DESY, Hamburg, Germany
  Funding: The work was partly supported by the program "Nauka" of the Russian Ministry of Education and Science, grant #3.1903.2017
The spatial resolution of an OTR monitor for electron beam profile diagnostics is determined by the resolution of the optical system and by the Point Spread Function (PSF) representing the single electron image. In the image plane, the PSF has a typical lobe-shape distribution with an inter-peak distance depending on wavelength and lens aperture ratio [*]. For a beam with a transverse rms size smaller than the distance, the reconstruction of the beam profile has several difficulties [**, ***]. We propose to reduce the PSF contribution and to improve the spatial resolution of an OTR monitor simply by rotating the lens optical axis with respect to the specular reflection direction. If the difference between the rotational angle and the lens aperture is much larger than the inverse Lorentz factor, the PSF has a Gaussian-like distribution which matches practically with the Airy distribution. Thus the resolution depends on wavelength and lens aperture. In principle, for lens apertures in the order of 0.1 rad such an approach should allow to measure beam sizes comparable to the wavelength of observation, using a simple deconvolution procedure for the measured image and the PSF.
* M. Castellano, V.Verzilov, Phys. Rev. ST-AB, 1 (1998).
** K.Kruchinin, S.T.Boogert, P.Karataev et al., Proc. IBIC 2013 (2013).
*** L.G. Sukhikh, A.P. Potylitsyn, G. Kube, Phys. Rev. AB 20 (2017).
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WEPB14 Recent Results on Non-invasive Beam Size Measurement Methods Based on Polarization Currents radiation, experiment, polarization, photon 464
  • S. Mazzoni, M. Bergamaschi, O.R. Jones, R. Kieffer, T. Lefèvre, F. Roncarolo
    CERN, Geneva, Switzerland
  • A. Aryshev, N. Terunuma
    KEK, Ibaraki, Japan
  • L.Y. Bartnik, M.G. Billing, J.V. Conway, M.J. Forster, Y.L.P. Fuentes, J.P. Shanks, S. Wang
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • V.V. Bleko, A.S. Konkov, A. Potylitsyn
    TPU, Tomsk, Russia
  • L. Bobb
    DLS, Oxfordshire, United Kingdom
  • P. Karataev, K. Lekomtsev
    JAI, Egham, Surrey, United Kingdom
  • P. Karataev
    Royal Holloway, University of London, Surrey, United Kingdom
  We present recent results on non-invasive beam profile measurement techniques based on Diffraction Radiation (DR) and Cherenkov Diffraction Radiation (ChDR). Both methods exploit the analysis of broadband electromagnetic radiation resulting from polarization currents produced in, or at the boundary of, a medium in close proximity of a charged particle beam. To increase the resolution of DR, measurements were performed in the UV range at a wavelength of 250 nm. With such configurations, sensitivity to the beam size of a 1.2 GeV electron beam below 10 um was observed at the Accelerator Test Facility (ATF) at KEK, Japan. In the case of the ChDR, a proof of principle study was carried out at the Cornell Electron Storage Ring (CESR) where beam profiles were measured in 2017 on a 5.3 GeV positron beam. At the time of writing an experiment to measure the resolution limit of ChDR has been launched at ATF where smaller beam sizes are available. We will present experimental results and discuss the application of such techniques for future accelerators.  
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WEPB18 Performance of a Reflective Microscope Objective in an X-ray Pinhole Camera photon, electron, emittance, storage-ring 477
  • L. Bobb, G. Rehm
    DLS, Oxfordshire, United Kingdom
  X-ray pinhole cameras are used to measure the transverse beam profile of the electron beam in the storage ring from which the emittance is calculated. As improvements to the accelerator lattice reduce the beam emittance, e.g. with upgrades to fourth generation synchrotron light sources, likewise the beam size will be reduced such that micron and sub-micron scale resolution is required for beam size measurement. Therefore the spatial resolution of the pinhole camera imaging system must be improved accordingly. Here, the performance of a reflective microscope objective is compared to the high quality refractive lens which is currently in use to image the scintillator screen to the camera. The modulation transfer functions for each system have been assessed and will be discussed.  
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WEPC04 Setup for Beam Profile Measurements using Optical Transition Radiation* radiation, electron, linac, diagnostics 494
  • J. Pforr, M. Arnold, T. Bahlo, L.E. Jürgensen, N. Pietralla, A. Rost
    TU Darmstadt, Darmstadt, Germany
  • F. Hug
    KPH, Mainz, Germany
  Funding: *Work supported by DFG through GRK 2128.
The S-DALINAC is a thrice-recirculating, superconducting linear electron accelerator at TU Darmstadt. It can provide beams of electrons with energies up to 130 MeV and currents of 20 µA. The accelerator performance was improved by an extension of the beam diagnostics, as this increases the reproducibility of the machine settings. Therefore, the installation of several beam profile measurement stations is planned, which should be operational down to a beam current of 100 nA, as this current is used for beam tuning. Combining these devices with a quadrupole scan also allows for emittance measurements. The beam profile measurements shall be done based on optical transition radiation (OTR), resulting from the penetration of relativistic electrons from vacuum into a metal target. The radiation can be detected using standard cameras that provide information on the two-dimensional particle distribution. This contribution will address the layout of the measurement stations and a first test measurement will be presented.
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THOA03 Progress on Transverse Beam Profile Measurement Using the Heterodyne Near Field Speckles Method at ALBA radiation, scattering, undulator, experiment 538
  • S. Mazzoni, F. Roncarolo, G. Trad
    CERN, Geneva, Switzerland
  • U. Iriso, C. Kamma-Lorger, A.A. Nosych
    ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
  • M.A.C. Potenza
    Universita' degli Studi di Milano & INFN, Milano, Italy
  • M. Siano
    Università degli Studi di Milano, Milano, Italy
  We present the recent developments of a study aiming at measuring the transverse beam profile using the Heterodyne Near Field Speckles (HNFS) method. The HNFS technique consists of a suspension of nanoparticles suspended in a liquid and illuminated by synchrotron radiation (either in the visible or in X-ray wavelength range). The transverse coherence of the source, and therefore, under the conditions of validity of the Van Cittert and Zernike theorem, the transverse electron beam size is retrieved from the interference between the transmitted beam and the spherical waves scattered by each nanoparticle. We here describe the fundamentals of this technique, as well as the recent experimental results obtained with 12 keV radiation at the NCD beamline at ALBA. The applicability of such technique for future accelerators (e.g. CLIC or FCC) is also discussed.  
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