Author: Bregliozzi, G.
Paper Title Page
MOPTS093 Ultra-High Vacuum Characterization of Molybdenum-Carbide Graphite for HL-LHC Collimators 1078
  • F. Carra, C. Accettura, A. Bertarelli, G. Bregliozzi, G. Cattenoz, S. Redaelli, M. Taborelli
    CERN, Meyrin, Switzerland
  • M. Beghi
    POLIMI, Milano, Italy
  • J. Guardia Valenzuela
    Universidad de Zaragoza, Zaragoza, Spain
  Funding: This work has received funding from the European Union’s Horizon 2020 Research and Innovation programme under Grant Agreement No. 730871. Research supported by the HL-LHC project
In view of the High-Luminosity upgrade of the Large Hadron Collider (LHC) collimation system, a family of novel molybdenum-carbide graphite (MoGr) composites was developed to meet the challenging requirements of HL-LHC beam-halo collimation, in particular the electrical conductivity and thermo-mechanical performances. The Ultra-High Vacuum (UHV) behaviour of this material was extensively characterized to assess its compatibility with the accelerator’s specifications. The results presented in this paper correlate the outgassing behaviour with the microscopic features of MoGr compared to other graphite-based materials. Residual gas analysis (RGA) was exploited to optimize post-production treatments.
DOI • reference for this paper ※  
About • paper received ※ 12 April 2019       paper accepted ※ 21 May 2019       issue date ※ 21 June 2019  
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WEPGW084 Measuring Beamsize with the LHC Beam Gas Vertex Detector 2680
SUSPFO109   use link to see paper's listing under its alternate paper code  
  • B. Würkner, A. Alexopoulos, C. Barschel, E. Bravin, G. Bregliozzi, N. Chritin, B. Dehning, M. Ferro-Luzzi, M. Giovannozzi, R. Jacobsson, L.K. Jensen, O.R. Jones, V. Kain, R. Kieffer, R. Matev, M.N. Rihl, V. Salustino Guimaraes, R. Veness, S. Vlachos
    CERN, Meyrin, Switzerland
  • A. Bay, F. Blanc, S. Gianì, O. Girard, G.J. Haefeli, P. Hopchev, A. Kuonen, T. Nakada, O. Schneider, M. Tobin, Z. Xu
    EPFL, Lausanne, Switzerland
  • R. Greim, T. Kirn, S. Schael, M. Wlochal
    RWTH, Aachen, Germany
  The Beam Gas Vertex detector (BGV) is an innovative beam profile monitor being developed as part of the High Luminosity LHC (HL-LHC) project at CERN. The goal is to continually measure the transverse beam size by reconstructing beam-gas interaction vertices using high precision tracking detectors. To confirm the feasibility of such a device, a demonstrator based on eight modules of scintillating fiber detectors has been constructed, installed in the LHC and operated for the past 3 years. It will be shown that using the BGV the average transverse beam size can be obtained with a statistical accuracy of better than 5µm (for a gaussian beam with a σ of 200µm). This precision is obtained with an integration time of less than one minute. In addition, the BGV measures the size of individual bunches with a statistical accuracy of better than 5% within 5 minutes. The results obtained from all the data gathered over the past 3 years will be presented and compared to measurements from other beam profile monitors. Some ideas for improvements for the final HL-LHC instrument will also be discussed.  
DOI • reference for this paper ※  
About • paper received ※ 10 May 2019       paper accepted ※ 19 May 2019       issue date ※ 21 June 2019  
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THPRB072 Operational Experience of a Prototype LHC Injection Kicker Magnet with a Low SEY Coating and Redistributed Power Deposition 3974
  • M.J. Barnes, C. Bracco, G. Bregliozzi, A. Chmielinska, L. Ducimetière, B. Goddard, G. Iadarola, T. Kramer, V. Vlachodimitropoulos, W.J.M. Weterings
    CERN, Geneva, Switzerland
  • A. Chmielinska
    EPFL, Lausanne, Switzerland
  • L. Vega Cid
    ETSII UPM, Madrid, Spain
  Funding: This research was supported by the HL-LHC project
In the event that it is necessary to exchange an LHC injection kicker magnet (MKI), the newly installed kicker magnet would limit HL-LHC operation for a few hundred hours due to dynamic vacuum activity. A surface coating with a low secondary electron yield, applied to the inner surface of an alumina tube to reduce dynamic vacuum activity without increasing the probability of UFOs, and which is compatible with the high voltage environment, was included in a prototype MKI installed in the LHC during the 2017-18 Year End Technical Stop. In addition, this MKI included an upgrade to relocate a significant portion of beam induced power from the yoke to a ’damping element’: this element is not at pulsed high voltage. The effectiveness of the upgrades has been demonstrated during LHC operation, hence a future version will include water cooling of this ’damping element’. This paper reviews dynamic vacuum around the MKIs and summarizes operational experience of the upgraded MKI.
DOI • reference for this paper ※  
About • paper received ※ 08 April 2019       paper accepted ※ 23 May 2019       issue date ※ 21 June 2019  
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