Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1. / Seeburn, Navin; the DEAP-3600 Collaboration.

In: Astroparticle Physics, Vol. 85, 12.2016, p. 1-23.

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Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1. / Seeburn, Navin; the DEAP-3600 Collaboration.

In: Astroparticle Physics, Vol. 85, 12.2016, p. 1-23.

Research output: Contribution to journalArticlepeer-review

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@article{1d593d02653b43ccb9f25e447ac2cdc8,
title = "Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1",
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.",
author = "Jocelyn Monroe and Navin Seeburn and {the DEAP-3600 Collaboration}",
year = "2016",
month = dec,
doi = "10.1016/j.astropartphys.2016.09.002",
language = "English",
volume = "85",
pages = "1--23",
journal = "Astroparticle Physics",
issn = "0927-6505",
publisher = "Elsevier",

}

RIS

TY - JOUR

T1 - Measurement of the scintillation time spectra and pulse-shape discrimination of low-energy β and nuclear recoils in liquid argon with DEAP-1

AU - Monroe, Jocelyn

AU - Seeburn, Navin

AU - the DEAP-3600 Collaboration

PY - 2016/12

Y1 - 2016/12

N2 - 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.

AB - 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.

U2 - 10.1016/j.astropartphys.2016.09.002

DO - 10.1016/j.astropartphys.2016.09.002

M3 - Article

VL - 85

SP - 1

EP - 23

JO - Astroparticle Physics

JF - Astroparticle Physics

SN - 0927-6505

ER -