Author: Nordt, A.
Paper Title Page
MOPPC004 Experiments on the Margin of Beam Induced Quenches for LHC Superconducting Quadrupole Magnet in the LHC 124
  • C. Bracco, W. Bartmann, M. Bednarek, B. Goddard, E.B. Holzer, A. Nordt, M. Sapinski, R. Schmidt, M. Solfaroli Camillocci, M. Zerlauth, E.N. del Busto
    CERN, Geneva, Switzerland
  Protection of LHC equipment relies on a complex system of collimators to capture injected or circulating beam in case of LHC injection kicker magnet failures. However, for specific failures of the injection kicker, the beam can graze the injection protection collimators and induce quenches of downstream superconducting magnets. This occurred twice during 2011 operation and can also not be excluded during further operation. Tests were performed during Machine Development periods of the LHC to assess the quench margin of the quadrupole located just downstream of the last injection protection collimator in point 8. In addition to the existing Quench Protection System, a special monitoring instrumentation was installed at this magnet to detect any resistance increase below the quench limit. The correlation between the magnet and Beam Loss Monitor signals was analysed for different beam intensities and magnet current. The results of the experiments are presented in this paper.  
THPPP086 UFOs in the LHC: Observations, Studies and Extrapolations 3936
  • T. Baer, M.J. Barnes, F. Cerutti, A. Ferrari, N. Garrel, B. Goddard, E.B. Holzer, S. Jackson, A. Lechner, V. Mertens, M. Misiowiec, E. Nebot Del Busto, A. Nordt, J.A. Uythoven, V. Vlachoudis, J. Wenninger, C. Zamantzas, F. Zimmermann
    CERN, Geneva, Switzerland
  • T. Baer
    University of Hamburg, Hamburg, Germany
  • N. Fuster Martinez
    Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain
  Unidentified falling objects (UFOs) are potentially a major luminosity limitation for nominal LHC operation. They are presumably micrometer sized dust particles which lead to fast beam losses when they interact with the beam. With large-scale increases and optimizations of the beam loss monitor (BLM) thresholds, their impact on LHC availability was mitigated from mid 2011 onwards. For higher beam energy and lower magnet quench limits, the problem is expected to be considerably worse, though. In 2011/12, the diagnostics for UFO events were significantly improved: dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. The state of knowledge, extrapolations for nominal LHC operation and mitigation strategies are presented.