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Beam-induced and cosmic-ray backgrounds observed in the ATLAS detector during the LHC 2012 proton-proton running period

Aad, G; Abbott, B.; Abdallah, J; Abdinov, O; Abeloos, B; Aben, R; Åkesson, Torsten LU ; Bocchetta, Simona LU ; Bryngemark, Lene LU and Doglioni, Caterina LU , et al. (2016) In Journal of Instrumentation 11(5).
Abstract
This paper discusses various observations on beam-induced and cosmic-ray backgrounds in the ATLAS detector during the LHC 2012 proton-proton run. Building on published results based on 2011 data, the correlations between background and residual pressure of the beam vacuum are revisited. Ghost charge evolution over 2012 and its role for backgrounds are evaluated. New methods to monitor ghost charge with beam-gas rates are presented and observations of LHC abort gap population by ghost charge are discussed in detail. Fake jets from colliding bunches and from ghost charge are analysed with improved methods, showing that ghost charge in individual radio-frequency buckets of the LHC can be resolved. Some results of two short periods of... (More)
This paper discusses various observations on beam-induced and cosmic-ray backgrounds in the ATLAS detector during the LHC 2012 proton-proton run. Building on published results based on 2011 data, the correlations between background and residual pressure of the beam vacuum are revisited. Ghost charge evolution over 2012 and its role for backgrounds are evaluated. New methods to monitor ghost charge with beam-gas rates are presented and observations of LHC abort gap population by ghost charge are discussed in detail. Fake jets from colliding bunches and from ghost charge are analysed with improved methods, showing that ghost charge in individual radio-frequency buckets of the LHC can be resolved. Some results of two short periods of dedicated cosmic-ray background data-taking are shown; in particular cosmic-ray muon induced fake jet rates are compared to Monte Carlo simulations and to the fake jet rates from beam background. A thorough analysis of a particular LHC fill, where abnormally high background was observed, is presented. Correlations between backgrounds and beam intensity losses in special fills with very high β∗ are studied. © 2016 CERN for the benefit of the ATLAS collaboration. (Less)
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@article{ce02b646-7540-4ccf-9309-4801a9c3e23f,
  abstract     = {This paper discusses various observations on beam-induced and cosmic-ray backgrounds in the ATLAS detector during the LHC 2012 proton-proton run. Building on published results based on 2011 data, the correlations between background and residual pressure of the beam vacuum are revisited. Ghost charge evolution over 2012 and its role for backgrounds are evaluated. New methods to monitor ghost charge with beam-gas rates are presented and observations of LHC abort gap population by ghost charge are discussed in detail. Fake jets from colliding bunches and from ghost charge are analysed with improved methods, showing that ghost charge in individual radio-frequency buckets of the LHC can be resolved. Some results of two short periods of dedicated cosmic-ray background data-taking are shown; in particular cosmic-ray muon induced fake jet rates are compared to Monte Carlo simulations and to the fake jet rates from beam background. A thorough analysis of a particular LHC fill, where abnormally high background was observed, is presented. Correlations between backgrounds and beam intensity losses in special fills with very high β∗ are studied. © 2016 CERN for the benefit of the ATLAS collaboration.},
  author       = {Aad, G and Abbott, B. and Abdallah, J and Abdinov, O and Abeloos, B and Aben, R and Åkesson, Torsten and Bocchetta, Simona and Bryngemark, Lene and Doglioni, Caterina and Floderus, Anders and Hawkins, Anthony and Hedberg, Vincent and Ivarsson, Jenny and Jarlskog, Göran and Lytken, Else and Mjörnmark, Ulf and Smirnova, Oxana and Viazlo, Oleksandr and , },
  issn         = {1748-0221},
  keyword      = {Beam-intensity monitors,Beam-line instrumentation (beam position and profile monitors,Bunch length monitors),Data analysis,Performance of high energy physics detectors,Cosmology,Data reduction,High energy physics,Intelligent systems,Monte Carlo methods,Beam intensity,Beam positions,Bunch length,Cosmic Ray Background,Cosmic-ray muons,High energy physics detector,Radio frequencies,Residual pressures,Cosmic rays},
  language     = {eng},
  number       = {5},
  publisher    = {IOP Publishing},
  series       = {Journal of Instrumentation},
  title        = {Beam-induced and cosmic-ray backgrounds observed in the ATLAS detector during the LHC 2012 proton-proton running period},
  url          = {http://dx.doi.org/10.1088/1748-0221/11/05/P05013},
  volume       = {11},
  year         = {2016},
}