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

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.

Akerib, D. S., Alsum, S., Araujo, H. M., Bai, X., Bailey, A. J., Balajthy, J., ... Zhang, C.

Akerib, DS||Alsum, S||Araujo, HM||Bai, X||Bailey, AJ||Balajthy, J||Beltrame, P||Bernard, EP||Bernstein, A||Biesiadzinski, TP||Boulton, EM||Bras, 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, D-M||Mock, J||Moongweluwan, M||Morad, JA||Murphy, A St J||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||Sumner, TJ||Szydagis, M||Taylor, DJ||Taylor, WC||Tennyson, BP||Terman, PA||Tiedt, DR||To, WH||Tripathi, M||Tvrznikova, L||Utku, U||Uvarov, S||Velan, V||Verbus, JR||Webb, RC||White, JT||Whitis, TJ||Witherell, MS||Wolfs, FLH||Xu, J||Yazdani, K||Young, SK||Zhang, C

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