skip to main content

DOE PAGESDOE PAGES

This content will become publicly available on September 11, 2019

Title: Surface background suppression in liquid argon dark matter detectors using a newly discovered time component of tetraphenyl-butadiene scintillation

Here, decays of radioisotopes on inner detector surfaces can pose a major background concern for the direct detection of dark matter. While these backgrounds are conventionally mitigated with position cuts, these cuts reduce the exposure of the detector by decreasing the sensitive mass, and uncertainty in position determination may make it impossible to adequately remove such events in certain detectors. In this paper, we provide a new technique for substantially reducing these surface backgrounds in liquid argon (LAr) detectors, independent of position cuts. These detectors typically use a coating of tetraphenyl-butadiene (TPB) on the inner surfaces as a wavelength shifter to convert vacuum ultraviolet (VUV) LAr scintillation light to the visible spectrum. We find that TPB scintillation contains a component with a previously unreported exceptionally long lifetime (~ms). We discovered that this component differs significantly in magnitude between alpha, beta, and VUV excitation, which enables the use of pulse shape discrimination to suppress surface backgrounds by more than a factor of 10 3 with negligible loss of dark matter sensitivity. We also discuss how this technique can be extended beyond just LAr experiments.
Authors:
 [1] ;  [2] ;  [3] ;  [4]
  1. Princeton Univ., Princeton, NJ (United States); Stanford Univ., Stanford, CA (United States)
  2. Princeton Univ., Princeton, NJ (United States); Carleton Univ., Ottawa, ON (Canada)
  3. Princeton Univ., Princeton, NJ (United States); Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  4. Princeton Univ., Princeton, NJ (United States)
Publication Date:
Report Number(s):
LLNL-JRNL-750996
Journal ID: ISSN 2470-0010; PRVDAQ; 936717
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Physical Review D
Additional Journal Information:
Journal Volume: 98; 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
OSTI Identifier:
1474352
Alternate Identifier(s):
OSTI ID: 1469414

Stanford, Chris, Westerdale, Shawn, Xu, Jingke, and Calaprice, Frank. Surface background suppression in liquid argon dark matter detectors using a newly discovered time component of tetraphenyl-butadiene scintillation. United States: N. p., Web. doi:10.1103/PhysRevD.98.062002.
Stanford, Chris, Westerdale, Shawn, Xu, Jingke, & Calaprice, Frank. Surface background suppression in liquid argon dark matter detectors using a newly discovered time component of tetraphenyl-butadiene scintillation. United States. doi:10.1103/PhysRevD.98.062002.
Stanford, Chris, Westerdale, Shawn, Xu, Jingke, and Calaprice, Frank. 2018. "Surface background suppression in liquid argon dark matter detectors using a newly discovered time component of tetraphenyl-butadiene scintillation". United States. doi:10.1103/PhysRevD.98.062002.
@article{osti_1474352,
title = {Surface background suppression in liquid argon dark matter detectors using a newly discovered time component of tetraphenyl-butadiene scintillation},
author = {Stanford, Chris and Westerdale, Shawn and Xu, Jingke and Calaprice, Frank},
abstractNote = {Here, decays of radioisotopes on inner detector surfaces can pose a major background concern for the direct detection of dark matter. While these backgrounds are conventionally mitigated with position cuts, these cuts reduce the exposure of the detector by decreasing the sensitive mass, and uncertainty in position determination may make it impossible to adequately remove such events in certain detectors. In this paper, we provide a new technique for substantially reducing these surface backgrounds in liquid argon (LAr) detectors, independent of position cuts. These detectors typically use a coating of tetraphenyl-butadiene (TPB) on the inner surfaces as a wavelength shifter to convert vacuum ultraviolet (VUV) LAr scintillation light to the visible spectrum. We find that TPB scintillation contains a component with a previously unreported exceptionally long lifetime (~ms). We discovered that this component differs significantly in magnitude between alpha, beta, and VUV excitation, which enables the use of pulse shape discrimination to suppress surface backgrounds by more than a factor of 103 with negligible loss of dark matter sensitivity. We also discuss how this technique can be extended beyond just LAr experiments.},
doi = {10.1103/PhysRevD.98.062002},
journal = {Physical Review D},
number = 6,
volume = 98,
place = {United States},
year = {2018},
month = {9}
}