The liquid-argon scintillation pulseshape in DEAP-3600
Open Access
- 4 April 2020
- journal article
- research article
- Published by Springer Science and Business Media LLC in The European Physical Journal C
- Vol. 80 (4), 1-12
- https://doi.org/10.1140/epjc/s10052-020-7789-x
Abstract
DEAP-3600 is a liquid-argon scintillation detector looking for dark matter. Scintillation events in the liquid argon (LAr) are registered by 255 photomultiplier tubes (PMTs), and pulseshape discrimination (PSD) is used to suppress electromagnetic background events. The excellent PSD performance of LAr makes it a viable target for dark matter searches, and the LAr scintillation pulseshape discussed here is the basis of PSD. The observed pulseshape is a combination of LAr scintillation physics with detector effects. We present a model for the pulseshape of electromagnetic background events in the energy region of interest for dark matter searches. The model is composed of (a) LAr scintillation physics, including the so-called intermediate component, (b) the time response of the TPB wavelength shifter, including delayed TPB emission at $${\mathcal {O}}$$ (ms) time-scales, and c) PMT response. TPB is the wavelength shifter of choice in most LAr detectors. We find that approximately 10% of the intensity of the wavelength-shifted light is in a long-lived state of TPB. This causes light from an event to spill into subsequent events to an extent not usually accounted for in the design and data analysis of LAr-based detectors.
Funding Information
- H2020 European Research Council (279980)
- Russian Science Foundation (16-12-10369)
- International Research Agenda Programme AstroCeNT
- Science and Technology Facilities Council (ST/K002570/1, ST/R002908/1)
- Ministry of Research and Innovation
- Canadian Foundation for Innovation
- Leverhulme Trust (ECF-20130496)
- Ministerio de Ciencia e Innovación (FPA2017-82647-P, MDM-2015-0509)
- Consejo Nacional de Ciencia y Tecnología (252167)
- Arthur B.McDonald Canadian Astroparticle Research Institute
- Canada First Research Excellence Fund
- Ministry of Advanced Education, Government of Alberta
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