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Title: Radiopurity measurement of acrylic for DEAP-3600

The spherical acrylic vessel that contains the liquid argon target is the most critical detector component in the DEAP-3600 dark matter experiment. Alpha decays near the inner surface of the acrylic vessel are one of the main sources of background in the detector. A fraction of the alpha energy, or the recoiling nucleus from the alpha decay, could misreconstruct in the fiducial volume and result in a false candidate dark matter event. Acrylic has low levels of inherent contamination from {sup 238}U and {sup 232}Th. Another background of particular concern is diffusion of {sup 222}Rn during manufacturing, leading to {sup 210}Pb contamination. The maximum acceptable concentrations in the DEAP-3600 acrylic vessel are ppt levels of {sup 238}U and {sup 232}Th equivalent, and 10{sup −8} ppt {sup 210}Pb. The impurities in the bulk acrylic will be measured by vaporizing a large quantity of acrylic and counting the concentrated residue with ultra-low background HPGe detectors and a low background alpha spectrometer. An overview of the acrylic assay technique is presented.
Authors:
;  [1] ;  [2]
  1. Department of Physics, Engineering Physics, and Astronomy, Queen's University, Kingston, Ontario K7L 3N6 (Canada)
  2. SNOLAB, Lively, Ontario P3Y 1N2 Canada and Department of Physics, Laurentian University, Sudbury, Ontario P3E 2C6 (Canada)
Publication Date:
OSTI Identifier:
22218178
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 1549; Journal Issue: 1; Conference: LRT 2013: 4. international workshop on low radioactivity techniques, Assergi (Italy), 10-12 Apr 2013; Other Information: (c) 2013 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND TECHNOLOGY; ALPHA DECAY; ALPHA SPECTROMETERS; ARGON; CONCENTRATION RATIO; CONTAMINATION; DIFFUSION; HIGH-PURITY GE DETECTORS; LEAD 210; LIQUID SCINTILLATION DETECTORS; MULTIPARTICLE SPECTROMETERS; NONLUMINOUS MATTER; RADON 222; RECOILS; THORIUM 232; URANIUM 238