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This content will become publicly available on September 19, 2018

Title: First measurement of surface nuclear recoil background for argon dark matter searches

Here, one major background in direct searches for weakly interacting massive particles (WIMPs) comes from the deposition of radon progeny on detector surfaces. A dangerous surface background is the 206Pb nuclear recoils produced by 210Po decays. In this paper, we report the first characterization of this background in liquid argon. The scintillation signal of low energy Pb recoils is measured to be highly quenched in argon, and we estimate that the 103 keV 206Pb recoil background will produce a signal equal to that of a ~5 keV (30 keV) electron recoil ( 40Ar recoil). In addition, we demonstrate that this dangerous 210Po surface background can be suppressed, using pulse shape discrimination methods, by a factor of ~100 or higher, which can make argon dark matter detectors near background-free and enhance their potential for discovery of medium- and high-mass WIMPs. Lastly, we also discuss the impact on other low background experiments.
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [1]
  1. Princeton Univ., NJ (United States). Department of Physics
  2. Queen's Univ., Kingston, ON (Canada). Department of Physics, Engineering Physics, and Astronomy
Publication Date:
Report Number(s):
LLNL-JRNL-703423
Journal ID: ISSN 2470-0010; PRVDAQ
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 96; Journal Issue: 6; Journal ID: ISSN 2470-0010
Publisher:
American Physical Society (APS)
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
OSTI Identifier:
1426118
Alternate Identifier(s):
OSTI ID: 1392729