Projects per year
Abstract
The DEAP-1 low-background liquid argon detector was used to measure scintillation pulse shapes of electron and nuclear recoil events and to demonstrate the feasibility of pulse-shape discrimination down to an electron-equivalent energy of 20 keVee.In the surface dataset using a triple-coincidence tag we found the fraction of β events that are misidentified as nuclear recoils to be <1.4×10−7 (90% C.L.) for energies between 43–86 keVee and for a nuclear recoil acceptance of at least 90%, with 4% systematic uncertainty on the absolute energy scale. The discrimination measurement on surface was limited by nuclear recoils induced by cosmic-ray generated neutrons. This was improved by moving the detector to the SNOLAB underground laboratory, where the reduced background rate allowed the same measurement to be done with only a double-coincidence tag.The combined data set contains 1.23 × 108 events. One of those, in the underground data set, is in the nuclear-recoil region of interest. Taking into account the expected background of 0.48 events coming from random pileup, the resulting upper limit on the level of electronic recoil contamination is <2.7×10−8 (90% C.L.) between 44–89 keVee and for a nuclear recoil acceptance of at least 90%, with 6% systematic uncertainty on the absolute energy scale.We developed a general mathematical framework to describe pulse-shape-discrimination parameter distributions and used it to build an analytical model of the distributions observed in DEAP-1. Using this model, we project a misidentification fraction of approximately 10−10 for an electron-equivalent energy threshold of 15 keVee for a detector with 8 PE/keVee light yield. This reduction enables a search for spin-independent scattering of WIMPs from 1000 kg of liquid argon with a WIMP-nucleon cross-section sensitivity of 10−46 cm2, assuming negligible contribution from nuclear recoil backgrounds.
Original language | English |
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Pages (from-to) | 1-23 |
Number of pages | 23 |
Journal | Astroparticle Physics |
Volume | 85 |
Early online date | 17 Sept 2016 |
DOIs | |
Publication status | Published - Dec 2016 |
Projects
- 2 Finished
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Liquid Argon Detector Calibration R& D for Dark Matter and Neutrino Physics
Monroe, J. & Nikkel, J. A.
Science and Technology Facilities Council
1/10/12 → 30/09/14
Project: Research
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DEAP/CLEAN Dark Matter Search
Monroe, J., Nikkel, J. A., Kemp, A., La Zia, F., Seeburn, N., Butcher, A., Fatemighomi, N. & Walding, J.
1/09/11 → 31/08/20
Project: Research
Activities
- 1 Membership of research network
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SNOLAB (External organisation)
Jocelyn Monroe (Participant)
2009 → …Activity: Membership › Membership of research network