Author: Grob, L. K.
Paper Title Page
MOPTS094 Dust Analysis from LHC Vacuum System to Identify the Source of Macro-Particle-Beam-Interactions 1082
SUSPFO100   use link to see paper's listing under its alternate paper code  
  • L. K. Grob, A. Apollonio, C. Charvet, E. Garcia-Tabares Valdivieso, H. Kos, R. Schmidt
    CERN, Geneva, Switzerland
  • C. Neves
    Hochschule Furtwangen, Furtwangen, Germany
  Since in 2010 the first sub-millisecond beam losses were observed at varying locations all along the LHC, it is well known that dust can interact with high-intensity proton beams and cause significant beam losses. Initially the sudden localized losses were enigmatic and coined the phrase ’unidentified falling objects’ (UFOs), which is still widely used. These very fast beam losses have resulted in hundreds of premature beam dumps and even magnet quenches since the start of LHC. So far, the only mitigation strategy involved an optimization of dump thresholds and the beneficial conditioning effect which leads to a reduction of the UFO rate over time. To understand the physics involved in these events and to allow an active diminution, it is essential to know the chemical composition and the size of the dust particulates interacting with the protons. The exchange of a dipole magnet offered the unique opportunity to collect dust samples from inside the LHC vacuum system. They were extracted from the various components and analyzed by scanning electron microscopy and energy-dispersive X-ray spectroscopy to reveal size distribution and abundant elements. The results of this investigation will optimize the existing UFO models and the improved understanding of the phenomenon may help to prevent future performance limitations. This is also of relevance for future projects, in particular for the Future Circular Collider (FCC) under study.  
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About • paper received ※ 15 May 2019       paper accepted ※ 24 May 2019       issue date ※ 21 June 2019  
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