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Liquid xenon scintillation measurements and pulse shape discrimination in the LUX dark matter detector

  • Author(s): Akerib, DS
  • Alsum, S
  • Araújo, HM
  • Bai, X
  • Bailey, AJ
  • Balajthy, J
  • Beltrame, P
  • Bernard, EP
  • Bernstein, A
  • Biesiadzinski, TP
  • Boulton, EM
  • Brás, P
  • Byram, D
  • Carmona-Benitez, MC
  • Chan, C
  • Currie, A
  • Cutter, JE
  • Davison, TJR
  • Dobi, A
  • Druszkiewicz, E
  • Edwards, BN
  • Fallon, SR
  • Fan, A
  • Fiorucci, S
  • Gaitskell, RJ
  • Genovesi, J
  • Ghag, C
  • Gilchriese, MGD
  • Hall, CR
  • Haselschwardt, SJ
  • Hertel, SA
  • Hogan, DP
  • Horn, M
  • Huang, DQ
  • Ignarra, CM
  • Jacobsen, RG
  • Ji, W
  • Kamdin, K
  • Kazkaz, K
  • Khaitan, D
  • Knoche, R
  • Lenardo, BG
  • Lesko, KT
  • Liao, J
  • Lindote, A
  • Lopes, MI
  • Manalaysay, A
  • Mannino, RL
  • Marzioni, MF
  • McKinsey, DN
  • Mei, DM
  • Mock, J
  • Moongweluwan, M
  • Morad, JA
  • Murphy, ASJ
  • Nehrkorn, C
  • Nelson, HN
  • Neves, F
  • O'Sullivan, K
  • Oliver-Mallory, KC
  • Palladino, KJ
  • Pease, EK
  • Rhyne, C
  • Shaw, S
  • Shutt, TA
  • Silva, C
  • Solmaz, M
  • Solovov, VN
  • Sorensen, P
  • et al.
Abstract

© 2018 American Physical Society. Weakly interacting massive particles (WIMPs) are a leading candidate for dark matter and are expected to produce nuclear recoil (NR) events within liquid xenon time-projection chambers. We present a measurement of the scintillation timing characteristics of liquid xenon in the LUX dark matter detector and develop a pulse shape discriminant to be used for particle identification. To accurately measure the timing characteristics, we develop a template-fitting method to reconstruct the detection times of photons. Analyzing calibration data collected during the 2013-2016 LUX WIMP search, we provide a new measurement of the singlet-to-triplet scintillation ratio for electron recoils (ER) below 46 keV, and we make, to our knowledge, a first-ever measurement of the NR singlet-to-triplet ratio at recoil energies below 74 keV. We exploit the difference of the photon time spectra for NR and ER events by using a prompt fraction discrimination parameter, which is optimized using calibration data to have the least number of ER events that occur in a 50% NR acceptance region. We then demonstrate how this discriminant can be used in conjunction with the charge-to-light discrimination to possibly improve the signal-to-noise ratio for nuclear recoils.

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