학술논문
Pulse-shape discrimination against low-energy Ar-39 beta decays in liquid argon with 4.5 tonne-years of DEAP-3600 data
Document Type
article
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
Source
European Physical Journal C: Particles and Fields, Vol 81, Iss 9, Pp 1-13 (2021)
Subject
Language
English
ISSN
1434-6044
1434-6052
1434-6052
Abstract
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 $$^{39}\text{ Ar }$$ 39 Ar beta decays and is suppressed using pulse-shape discrimination (PSD). We use two types of PSD estimator: 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 mean single-photoelectron charge, 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 pulse shape 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.