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arXiv · 1802.06162

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

The LUX Collaboration·D. S. Akerib·S. Alsum·H. M. Araújo·X. Bai·A. J. Bailey·J. Balajthy·P. Beltrame·E. P. Bernard·A. Bernstein·T. P. Biesiadzinski·E. M. Boulton·P. Brás·D. Byram·M. C. Carmona-Benitez·C. Chan·A. Currie·J. E. Cutter·T. J. R. Davison·A. Dobi·E. Druszkiewicz·B. N. Edwards·S. R. Fallon·A. Fan·S. Fiorucci·R. J. Gaitskell·J. Genovesi·C. Ghag·M. G. D. Gilchriese·C. R. Hall·S. J. Haselschwardt·S. A. Hertel·D. P. Hogan·M. Horn·D. Q. Huang·C. M. Ignarra·R. G. Jacobsen·W. Ji·K. Kamdin·K. Kazkaz·D. Khaitan·R. Knoche·B. G. Lenardo·K. T. Lesko·J. Liao·A. Lindote·M. I. Lopes·A. Manalaysay·R. L. Mannino·M. F. Marzioni·D. N. McKinsey·D. M. Mei·J. Mock·M. Moongweluwan·J. A. Morad·A. St. J. Murphy·C. Nehrkorn·H. N. Nelson·F. Neves·K. O'Sullivan·K. C. Oliver-Mallory·K. J. Palladino·E. K. Pease·C. Rhyne·S. Shaw·T. A. Shutt·C. Silva·M. Solmaz·V. N. Solovov·P. Sorensen·T. J. Sumner·M. Szydagis·D. J. Taylor·W. C. Taylor·B. P. Tennyson·P. A. Terman·D. R. Tiedt·W. H. To·M. Tripathi·L. Tvrznikova·U. Utku·S. Uvarov·V. Velan·J. R. Verbus·R. C. Webb·J. T. White·T. J. Whitis·M. S. Witherell·F. L. H. Wolfs·J. Xu·K. Yazdani·S. K. Young·C. Zhang
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Abstract

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 2013-16 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 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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The LUX Collaboration, D. S. Akerib, S. Alsum, H. M. Araújo, X. Bai, A. J. Bailey, J. Balajthy, P. Beltrame, E. P. Bernard, A. Bernstein, T. P. Biesiadzinski, E. M. Boulton, P. Brás, D. Byram, M. C. Carmona-Benitez, C. Chan, A. Currie, J. E. Cutter, T. J. R. Davison, A. Dobi, E. Druszkiewicz, B. N. Edwards, S. R. Fallon, A. Fan, S. Fiorucci, R. J. Gaitskell, J. Genovesi, C. Ghag, M. G. D. Gilchriese, C. R. Hall, S. J. Haselschwardt, S. A. Hertel, D. P. Hogan, M. Horn, D. Q. Huang, C. M. Ignarra, R. G. Jacobsen, W. Ji, K. Kamdin, K. Kazkaz, D. Khaitan, R. Knoche, B. G. Lenardo, K. T. Lesko, J. Liao, A. Lindote, M. I. Lopes, A. Manalaysay, R. L. Mannino, M. F. Marzioni, D. N. McKinsey, D. M. Mei, J. Mock, M. Moongweluwan, J. A. Morad, A. St. J. Murphy, C. Nehrkorn, H. N. Nelson, F. Neves, K. O'Sullivan, K. C. Oliver-Mallory, K. J. Palladino, E. K. Pease, C. Rhyne, S. Shaw, T. A. Shutt, C. Silva, M. Solmaz, V. N. Solovov, P. Sorensen, T. J. Sumner, M. Szydagis, D. J. Taylor, W. C. Taylor, B. P. Tennyson, P. A. Terman, D. R. Tiedt, W. H. To, M. Tripathi, L. Tvrznikova, U. Utku, S. Uvarov, V. Velan, J. R. Verbus, R. C. Webb, J. T. White, T. J. Whitis, M. S. Witherell, F. L. H. Wolfs, J. Xu, K. Yazdani, S. K. Young, C. Zhang. 2018-02-17. Liquid xenon scintillation measurements and pulse shape discrimination in the LUX dark matter detector. https://doi.org/10.1103/physrevd.97.112002

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