Details

Autor(en) / Beteiligte

• Amaudruz, P.-A.
• Batygov, M.
• Beltran, B.
• Bonatt, J.
• Boudjemline, K.
• Boulay, M.G.
• Broerman, B.
• Bueno, J.F.
• Butcher, A.
• Cai, B.
• Caldwell, T.
• Chen, M.
• Chouinard, R.
• Cleveland, B.T.
• Cranshaw, D.
• Dering, K.
• Duncan, F.
• Fatemighomi, N.
• Ford, R.
• Gagnon, R.
• Giampa, P.
• Giuliani, F.
• Gold, M.
• Golovko, V.V.
• Gorel, P.
• Grace, E.
• Graham, K.
• Grant, D.R.
• Hakobyan, R.
• Hallin, A.L.
• Hamstra, M.
• Harvey, P.
• Hearns, C.
• Hofgartner, J.
• Jillings, C.J.
• Kuźniak, M.
• Lawson, I.
• La Zia, F.
• Li, O.
• Lidgard, J.J.
• Liimatainen, P.
• Lippincott, W.H.
• Mathew, R.
• McDonald, A.B.
• McElroy, T.
• McFarlane, K.
• McKinsey, D.N.
• Mehdiyev, R.
• Monroe, J.
• Muir, A.
• Nantais, C.
• Nicolics, K.
• Nikkel, J.
• Noble, A.J.
• O’Dwyer, E.
• Olsen, K.
• Ouellet, C.
• Pasuthip, P.
• Peeters, S.J.M.
• Pollmann, T.
• Rau, W.
• Retière, F.
• Ronquest, M.
• Seeburn, N.
• Skensved, P.
• Smith, B.
• Sonley, T.
• Tang, J.
• Vázquez-Jáuregui, E.
• Veloce, L.
• Walding, J.
• Ward, M.

Titel

Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1

Ist Teil von

• Astroparticle physics, 2016-12, Vol.85 (C), p.1-23

Ort / Verlag

United States: Elsevier B.V

Erscheinungsjahr

2016

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• 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.