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This content will become publicly available on June 11, 2019

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

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. Furthermore, 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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Publication Date:
Grant/Contract Number:
AC02-76SF00515; AC02-05CH11231; AC05-06OR23100; AC52-07NA27344; FG01-91ER40618; FG02-08ER41549; FG02-11ER41738; FG02-91ER40674; FG02-91ER40688; FG02-95ER40917; NA0000979; SC0006605; SC0010010; SC0015535; PHY-0750671; PHY-0801536; PHY-1003660; PHY-1004661; PHY-1102470; PHY-1312561; PHY-1347449; PHY-1505868; PHY-1636738; RA0350; PTDC/FIS-NUC/1525/2014; LLNL-JRNL-752062
Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 97; Journal Issue: 11; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Research Org:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org:
USDOE
Contributing Orgs:
LUX Collaboration
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; 79 ASTRONOMY AND ASTROPHYSICS
OSTI Identifier:
1457784