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Title: Characterization of an ultra-high purity NaI(Tl) crystal scintillator with the SABRE Proof-of-Principle detector
Abstract The SABRE experiment aims to detect the annual modulation of the dark matter interaction rate by means of ultra-high purity NaI(Tl) crystals. It focuses on the achievement of a very low background to carry out a model-independent and high sensitivity test of the long-standing DAMA result. SABRE has recently completed a Proof-of-Principle (PoP) phase at the Gran Sasso National Laboratory, devoted to assess the radiopurity of the crystals. The results on the radiopurity of a 3.4-kg NaI(Tl) crystal scintillator grown within the SABRE Collaboration and operated underground in the SABRE-PoP setup, will be reported and discussed. The amount of potassium content in the crystal, determined by direct counting of 40 K, is found to be < 4.7 ppb at 90% CL. The average background rate in the 1-6 keV energy region of interest (ROI) is 1.20 ± 0.05 counts/day/kg/keV, which is, for the first time, comparable with DAMA/LIBRA-phasel. Our background model indicates that this rate is dominated by 210 Pb, and that about half of this contamination is located in the PTFE reflector wrapped around the crystal. Ongoing developments aimed at a further reduction of radioactive contaminants in the crystal indicates that a background rate ≤ 0.3 counts/day/kg/keV in more » the ROI is within reach. This value represents a benchmark for the development of next-generation NaI(Tl) detector arrays for the direct detection of dark matter particles. « less
Authors:
Award ID(s):
2014198 1620085
Publication Date:
NSF-PAR ID:
10353459
Journal Name:
Journal of Physics: Conference Series
Volume:
2156
Issue:
1
Page Range or eLocation-ID:
012022
ISSN:
1742-6588
Sponsoring Org:
National Science Foundation
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