The Effects of Dissolved Methane upon Liquid Argon Scintillation Light

Abstract

In this paper we report on measurements of the effects of dissolved methane upon argon scintillation light. We monitor the light yield from an alpha source held 20 cm from a cryogenic photomultiplier tube (PMT) assembly as methane is injected into a high-purity liquid argon volume. We observe significant suppression of the scintillation light yield by dissolved methane at the 10 part per billion (ppb) level. By examining the late scintillation light time constant, we determine that this loss is caused by an absorption process and also see some evidence of methane-induced scintillation quenching at higher concentrations (50-100 ppb). Using a second PMT assembly we look for visible re-emission features from the dissolved methane which have been reported in gas-phase argon methane mixtures, and we find no evidence of visible re-emission from liquid-phase argon methane mixtures at concentrations between 10 ppb and 0.1%.

18 pages, 11 figures Updated to match published version

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Cited by in corpus (11)

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• The liquid-argon scintillation pulseshape in DEAP-3600
• Summary of the Second Workshop on Liquid Argon Time Projection Chamber Research and Development in the United States
• Study of scintillation light collection, production and propagation in a 4 tonne dual-phase LArTPC
• Improved TPB-coated Light Guides for Liquid Argon TPC Light Detection Systems
• Liquid argon scintillation response to electronic recoils between $2.8$--$1275\mathrm{keV}$ in a high light yield single-phase detector
• Study of visible-light emission in pure and methane-doped liquid argon
• Observation of primary scintillations in the visible range in liquid argon doped with methane
• In-situ measurement of the scintillation light attenuation in liquid argon in the GERDA experiment
• A Model for the Global Quantum Efficiency for a TPB-based Wavelength-Shifting System used with Photomultiplier Tubes in Liquid Argon in MicroBooNE