1. Pulse-shape discrimination against low-energy Ar-39 β decays in liquid argon with 4.5 tonne-years of DEAP-3600 data
- Author
-
P. Adhikari, R. Ajaj, M. Alpízar-Venegas, P.-A. Amaudruz, D. J. Auty, M. Batygov, B. Beltran, H. Benmansour, C. E. Bina, J. Bonatt, W. Bonivento, M. G. Boulay, B. Broerman, J. F. Bueno, P. M. Burghardt, A. Butcher, M. Cadeddu, B. Cai, M. Cárdenas-Montes, S. Cavuoti, M. Chen, Y. Chen, B. T. Cleveland, J. M. Corning, D. Cranshaw, S. Daugherty, P. DelGobbo, K. Dering, J. DiGioseffo, P. Di Stefano, L. Doria, F. A. Duncan, M. Dunford, E. Ellingwood, A. Erlandson, S. S. Farahani, N. Fatemighomi, G. Fiorillo, S. Florian, T. Flower, R. J. Ford, R. Gagnon, D. Gallacher, P. García Abia, S. Garg, P. Giampa, D. Goeldi, V. Golovko, P. Gorel, K. Graham, D. R. Grant, A. Grobov, A. L. Hallin, M. Hamstra, P. J. Harvey, C. Hearns, T. Hugues, A. Ilyasov, A. Joy, B. Jigmeddorj, C. J. Jillings, O. Kamaev, G. Kaur, A. Kemp, I. Kochanek, M. Kuźniak, M. Lai, S. Langrock, B. Lehnert, A. Leonhardt, N. Levashko, X. Li, J. Lidgard, T. Lindner, M. Lissia, J. Lock, G. Longo, I. Machulin, A. B. McDonald, T. McElroy, T. McGinn, J. B. McLaughlin, R. Mehdiyev, C. Mielnichuk, J. Monroe, P. Nadeau, C. Nantais, C. Ng, A. J. Noble, E. O’Dwyer, G. Oliviéro, C. Ouellet, S. Pal, P. Pasuthip, S. J. M. Peeters, M. Perry, V. Pesudo, E. Picciau, M.-C. Piro, T. R. Pollmann, E. T. Rand, C. Rethmeier, F. Retière, I. Rodríguez-García, L. Roszkowski, J. B. Ruhland, E. Sánchez-García, R. Santorelli, D. Sinclair, P. Skensved, B. Smith, N. J. T. Smith, T. Sonley, J. Soukup, R. Stainforth, C. Stone, V. Strickland, M. Stringer, B. Sur, J. Tang, E. Vázquez-Jáuregui, S. Viel, J. Walding, M. Waqar, M. Ward, S. Westerdale, J. Willis, A. Zuñiga-Reyes, DEAP Collaboration, and Astroparticle Physics (IHEF, IoP, FNWI)
- Subjects
Physics - Instrumentation and Detectors ,Photon ,Physics and Astronomy (miscellaneous) ,Regular Article - Experimental Physics ,Physics::Instrumentation and Detectors ,Dark matter ,FOS: Physical sciences ,QC770-798 ,Astrophysics ,Computer Science::Digital Libraries ,01 natural sciences ,7. Clean energy ,Signal ,DEAP ,Nuclear and particle physics. Atomic energy. Radioactivity ,0103 physical sciences ,010306 general physics ,Instrumentation and Methods for Astrophysics (astro-ph.IM) ,Engineering (miscellaneous) ,Physics ,Scintillation ,010308 nuclear & particles physics ,Scattering ,Detector ,Instrumentation and Detectors (physics.ins-det) ,3. Good health ,Computational physics ,Pulse (physics) ,QB460-466 ,Computer Science::Mathematical Software ,Astrophysics - Instrumentation and Methods for Astrophysics - Abstract
The DEAP-3600 detector searches for the scintillation signal from dark matter particles scattering on a 3.3 tonne liquid argon target. The largest background comes from $^{39}$Ar beta decays and is suppressed using pulseshape discrimination (PSD). We use two types of PSD algorithm: the prompt-fraction, which considers the fraction of the scintillation signal in a narrow and a wide time window around the event peak, and the log-likelihood-ratio, which compares the observed photon arrival times to a signal and a background model. We furthermore use two algorithms to determine the number of photons detected at a given time: (1) simply dividing the charge of each PMT pulse by the charge of a single photoelectron, and (2) a likelihood analysis that considers the probability to detect a certain number of photons at a given time, based on a model for the scintillation pulseshape and for afterpulsing in the light detectors. The prompt-fraction performs approximately as well as the log-likelihood-ratio PSD algorithm if the photon detection times are not biased by detector effects. We explain this result using a model for the information carried by scintillation photons as a function of the time when they are detected., 14 pages, 9 figures
- Published
- 2021