Keyword: collider
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MOPC19 Virtual Signal Spectrum Analyzer Development Based On RedPitaya and EPICS for Tune Measurement in BEPCII EPICS, controls, synchrotron, interface 159
  • Y.H. Lu, J. He
    IHEP, Beijing, People's Republic of China
  An independent tune measurement system was developed in BEPCII with Direct Diode Detect (3D) technique. The system includes two diagonal electrode signals of a set of BPM, a self-developed board based on Direct Diode Detect (3D) technique, and a commercial virtual spectrum analyzer with a proprietary GUI client. Based on the open source digital electronics RedPitaya and open source software Spectrum, a device driver was developed based on EPICS and ASYN support for replacement of the commercial virtual spectrum analyzers and integration with the central system EPICS. According to the application requirements of tune measurement in BEPCII, the device driver finds the frequency point and power value corresponding to the X&Y tune between 631 to 800 kHz. The spectral resolution is 119 Hz. An EPICS IOC was built and run on RedPitaya for accessing the device driver. A CSS-based user interface shows the signal's power spectra and the tune frequency directly.  
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TUPA15 Adaptive Collimator Design for Future Particle Accelerators vacuum, collimation, site, operation 240
  • T.R. Furness, S. Fletcher, J.F. Williamson
    University of Huddersfield, Huddersfield, United Kingdom
  • A. Bertarelli, F. Carra, L. Gentini, M. Pasquali, S. Redaelli
    CERN, Geneva, Switzerland
  Funding: This work has recevied funding from the Science & Technology Facilities Council (STFC) and, the European Organization for Nuclear Research (CERN)
The function of collimators in the LHC is to control and safely dispose of the halo particles that are produced by unavoidable beam losses from the circulating beam. Even tiny proportions of the 7TeV beam have the stored energy to quench the superconducting magnets or damage parts of the accelerator if left unchecked. Particle absorbing Low-Z material make up the active area of the collimator (jaws). Various beam impact scenarios can induce significant temperature gradients that cause deformation of the jaws. This can lead to a reduction in beam cleaning efficiency which can have a detrimental effect on beam dynamics. This has led to research into a new Adaptive collimation system (ACS). The ACS is a re-design of a current collimator already in use at CERN. The ACS will incorporate a novel fibre based measurement system and piezoceramic actuators mounted within the body of the collimator to maintain jaw straightness below the 100µm specification. These two systems working in tandem can monitor, and correct for, the jaw structural deformation for all impact events. This paper details the concept and technical solutions of the ACS as well as preliminary validation calculations.
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WEPA18 Development of Longitudinal Beam Profile Diagnostics for Beam-beam Effects Study at VEPP-2000 electron, synchrotron, positron, injection 410
  • M.V. Timoshenko, V.M. Borin, O.I. Meshkov, Yu. A. Rogovsky, D.B. Shwartz, Yu.M. Zharinov
    BINP SB RAS, Novosibirsk, Russia
  • V.L. Dorokhov
    BINP, Novosibirsk, Russia
  The comprehensive development of beam longitudinal profile measurement systems based on stroboscopic optical dissector has started at VEPP-2000 electron-positron collider complex. The dissector was setted and commissioned at booster ring BEP that was deeply upgraded (2013-2015) to achieve top energy of 1 GeV. Bunch lengthening with current was studied at BEP with its new RF-cavity. In addition the method of synchrotron frequency measurement by dissector was applied. After dissector checkouts at BEP the similar studies were carried out with a single beam at VEPP-2000 storage ring in parallel with streak-camera measurements. Good agreement of results was observed. Series of single-turn longitudinal and vertical bunch profiles snapshots was made by streak-camera with respect to delay after counter beam injection. The unexpected longitudinal beam dynamics was observed for intensities above the beam-beam threshold. These studies together with beam-beam coherent oscillations spectra seen by pickups are of a great interest for understanding of flip-flop phenomenon which establish a fundamental luminosity limit at VEPP-2000 operating with round beams.  
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WEPB10 Grating Scanner for Measurement of Micron-size Beam Profiles electron, photon, simulation, positron 448
  • L.G. Sukhikh, A. Potylitsyn, S.A. Strokov
    TPU, Tomsk, Russia
  • G. Kube, K. Wittenburg
    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
Wire scanners are widely used for transverse beam size diagnostics. The minimum detectable beam size is affected by the diameter of a single wire. The smallest carbon or tungsten wires used so far have diameters of about 4 microns. With the development of modern electron accelerators and the demands from future linear electron-positron colliders, sub-micron beam sizes have to be resolved. In order to increase the resolution, the decrease of the wire diameter is required. The authors of Ref. * proposed to manufacture thin gold stripes of rectangular shape (widths are equal to 1 µm or 2 µm and height is equal to 3 µm) on Si3N4 membrane. We propose to use another arrangement of gold stripes with varying period on a Si substrate. A set of 11 stripes with 1 µm width and 10 micron height with varying gap width in the range 3-0.25 µm ("grating scanner") was simulated by using an analytical model and by the Geant4 code. By moving this scanner across the beam one could measure the Bremsstrahlung yield vs. the coordinate, resulting in an oscillating dependence. The visibility of the resulting image allows defining the beam sizes in the range of 0.5-1.5 µm for the proposed scanner parameters.
* S. Borrelli et al., "Generation and Measurement of Sub-Micrometer Relativistic Electron Beams", arXiv:1804.04252v1 [physics.acc-ph] 11 Apr 2018
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