Author: Rossi, A.
Paper Title Page
WEPMW028 First Attempts at using Active Halo Control at the LHC 2486
  • J.F. Wagner
    Goethe Universität Frankfurt, Frankfurt am Main, Germany
  • R. Bruce, H. Garcia Morales, W. Höfle, G. Kotzian, R. Kwee-Hinzmann, A. Langner, A. Mereghetti, E. Quaranta, S. Redaelli, A. Rossi, B. Salvachua, R. Tomás, G. Valentino, D. Valuch, J.F. Wagner
    CERN, Geneva, Switzerland
  • G. Stancari
    Fermilab, Batavia, Illinois, USA
  Funding: Research supported by the High Luminosity LHC project.
The beam halo population is a non-negligible factor for the performance of the LHC collimation system and the machine protection. In particular this could become crucial for aiming at stored beam energies of 700 MJ in the High Luminosity (HL-LHC) project, in order to avoid beam dumps caused by orbit jitter and to ensure safety during a crab cavity failure. Therefore several techniques to safely deplete the halo, i.e. active halo control, are under development. In a first attempt a novel way for safe halo depletion was tested with particle narrow-band excitation employing the LHC Transverse Damper (ADT). At an energy of 450 GeV a bunch selective beam tail scraping without affecting the core distribution was attempted. This paper presents the first measurement results, as well as a simple simulation to model the underlying dynamics.
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW028  
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WEPMW031 Towards Optimum Material Choices for the HL-LHC Collimator Upgrade 2498
  • E. Quaranta, A. Bertarelli, N. Biancacci, R. Bruce, F. Carra, E. Métral, S. Redaelli, A. Rossi, B. Salvant
    CERN, Geneva, Switzerland
  • F. Carra
    Politecnico di Torino, Torino, Italy
  The first years of operation at the LHC showed that collimator material-related concerns might limit the performance. In addition, the HL-LHC upgrade will bring the accelerator beyond the nominal performance through more intense and brighter proton beams. A new generation of collimators based on advanced materials is needed to match present and new requirements. After several years of R&D on collimator materials, studying the behaviour of novel composites with properties that address different limitations of the present collimation system, solutions have been found to fulfil various upgrade challenges. This paper describes the proposed staged approach to deploy new materials in the upgraded HL-LHC collimation system. Beam tests at the CERN HiRadMat facility were also performed to benchmark simulation methods and constitutive material models.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW031  
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WEPMW032 Radiation-induced Effects on LHC Collimator Materials under Extreme Beam Conditions 2502
  • E. Quaranta, A. Bertarelli, F. Carra, P.D. Hermes, S. Redaelli, A. Rossi
    CERN, Geneva, Switzerland
  • K. Bunk
    Goethe Universität Frankfurt, Frankfurt am Main, Germany
  • F. Carra
    Politecnico di Torino, Torino, Italy
  • J. Guardia Valenzuela
    Universidad de Zaragoza, Zaragoza, Spain
  • P.D. Hermes
    Westfaelische Wilhelms-Universität Muenster, Muenster, Germany
  • C.L. Hubert, M. Tomut
    GSI, Darmstadt, Germany
  • P. Nocera
    Università di Roma I La Sapienza, Roma, Italy
  • C. Porth
    TU Darmstadt, Darmstadt, Germany
  • N. Simos
    BNL, Upton, Long Island, New York, USA
  Over the last years, several samples of present and novel LHC collimator materials were irradiated under various beam conditions (using protons, fast neutrons, light and heavy ions at different energies and fluences) in different facilities around the world. This was achieved through an international collaboration including many companies and laboratories over the world. The main goal of the beam tests and the post-irradiation campaign is the definition of a threshold for radiation damage above which LHC collimators need to be replaced. In this paper, highlights of the measurements performed will be presented. First conclusions from the available data are also discussed.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW032  
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