The liquid-argon scintillation pulseshape in DEAP-3600

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.

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Cited by in corpus (16)

• Constraints on dark matter-nucleon effective couplings in the presence of kinematically distinct halo substructures using the DEAP-3600 detector
• Pulseshape discrimination against low-energy Ar-39 beta decays in liquid argon with 4.5 tonne-years of DEAP-3600 data
• SiPM cross-talk in liquid argon detectors
• R&D of Wavelength-Shifting Reflectors and Characterization of the Quantum Efficiency of Tetraphenyl Butadiene and Polyethylene Naphthalate in Liquid Argon
• Spectroscopic analysis of the argon scintillation with a wavelength sensitive particle detector
• Neutrino Backgrounds in Future Liquid Noble Element Dark Matter Direct Detection Experiments
• The science and technology of liquid argon detectors
• Recent results from DEAP-3600
• Scintillation and optical properties of xenon-doped liquid argon
• Development and characterization of a slow wavelength shifting coating for background rejection in liquid argon detectors
• Direct Measurement of the ${}^{39}$Ar Half-life from 3.4 Years of Data with the DEAP-3600 Detector
• Relative Measurement and Extrapolation of the Scintillation Quenching Factor of $\alpha$-Particles in Liquid Argon using DEAP-3600 Data
• Impact of extreme ultraviolet radiation on the scintillation of pure and xenon-doped liquid argon
• State of the Art in Direct Dark Matter Detectors: Technologies, Performance, and Future Directions
• Status of the DEAP-3600 experiment
• Measuring the Neutrino Event Time in Liquid Argon by a Post-Reconstruction One-parameter Fit