Search for dark matter with a 231-day exposure of liquid argon using DEAP-3600 at SNOLAB

• Published in: arXiv.org 2019-07
• Main Authors: Ajaj, R, P -A Amaudruz, Araujo, G R, Baldwin, M, Batygov, M, Beltran, B, Bina, C E, Bonatt, J, Boulay, M G, Broerman, B, Bueno, J F, Burghardt, P M, Butcher, A, Cai, B, Cavuoti, S, Chen, M, Chen, Y, Cleveland, B T, Cranshaw, D, Dering, K, DiGioseffo, J, Doria, L, Duncan, F A, Dunford, M, Erlandson, A, Fatemighomi, N, Fiorillo, G, Florian, S, Flower, A, d, R J, Gagnon, R, Gallacher, D, Garcés, E A, Garg, S, Giampa, P, Goeldi, D, Golovko, V V, Gorel, P, Graham, K, Grant, D R, Hallin, A L, Hamstra, M, Harvey, P J, Hearns, C, Joy, A, Jillings, C J, Kamaev, O, Kaur, G, Kemp, A, Kochanek, I, Kuźniak, M, Langrock, S, La Zia, F, X Li, Lidgard, J, Lindner, T, Litvinov, O, Lock, J, Longo, G, Majewski, P, McDonald, A B, McElroy, T, McGinn, T, McLaughlin, J B, Mehdiyev, R, Mielnichuk, C, Monroe, J, Nadeau, P, Nantais, C, C Ng, Noble, A J, O'Dwyer, E, Ouellet, C, Pasuthip, P, Peeters, S J M, M -C Piro, Pollmann, T R, Rand, E T, Rethmeier, C, Retière, F, Seeburn, N, Singhrao, K, Skensved, P, Smith, B, Smith, N J T, Sonley, T, Soukup, J, Stainforth, R, Stone, C, Strickland, V, Sur, B, Tang, J, Vázquez-Jáuregui, E, Veloce, L, Viel, S, Walding, J, Waqar, M, Ward, M, Westerdale, S, Willis, J
• Format: Article
• Language: English
• Subjects: Algorithms; Argon; Bayesian analysis; Dark matter; Discrimination; Energy resolution; Photoelectrons; Weakly interacting massive particles
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.1902.04048

DEAP-3600 is a single-phase liquid argon (LAr) direct-detection dark matter experiment, operating 2 km underground at SNOLAB (Sudbury, Canada). The detector consists of 3279 kg of LAr contained in a spherical acrylic vessel. This paper reports on the analysis of a 758 tonne\cdot day exposure taken over a period of 231 live-days during the first year of operation. No candidate signal events are observed in the WIMP-search region of interest, which results in the leading limit on the WIMP-nucleon spin-independent cross section on a LAr target of \(3.9\times10^{-45}\) cm\(^{2}\) (\(1.5\times10^{-44}\) cm\(^{2}\)) for a 100 GeV/c\(^{2}\) (1 TeV/c\(^{2}\)) WIMP mass at 90\% C. L. In addition to a detailed background model, this analysis demonstrates the best pulse-shape discrimination in LAr at threshold, employs a Bayesian photoelectron-counting technique to improve the energy resolution and discrimination efficiency, and utilizes two position reconstruction algorithms based on PMT charge and photon arrival times.