Proportional electroluminescence in two-phase argon and its relevance to rare-event experiments

Abstract

Proportional electroluminescence (EL) in gaseous Ar has for the first time been systematically studied in the two-phase mode, at 87 K and 1.00 atm. Liquid argon had a minor (56 ppm) admixture of nitrogen, which allowed to understand, inter alia, the effect of N2 doping on the EL mechanism in rare-event experiments using two-phase Ar detectors. The measurements were performed in a two-phase Cryogenic Avalanche Detector (CRAD) with EL gap located directly above the liquid-gas interface. The EL gap was optically read out in the Vacuum Ultraviolet (VUV), near 128 nm (Ar excimer emission), and in the near Ultraviolet (UV), at 300-450 nm (N2 Second Positive System emission), via cryogenic PMTs and a Geiger-mode APD (GAPD). Proportional electroluminescence was measured to have an amplification parameter of 109+-10 photons per drifting electron per kV overall in the VUV and UV, of which 51+-6% were emitted in the UV. The measured EL threshold, at an electric field of 3.7+-0.2 kV/cm, was in accordance with that predicted by the theory. The latter result is particularly relevant to DarkSide and SCENE dark matter search-related experiments, where the operation electric field was thereby on the verge of appearance of the S2 (ionization-induced) signal. The results obtained pave the way to the development of N2-doped two-phase Ar detectors with enhanced sensitivity to the S2 signal.

6 pages, 4 figures. Replaced to match journal version

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Cited by in corpus (8)

• Revealing neutral bremsstrahlung in two-phase argon electroluminescence
• Photon emission and atomic collision processes in two-phase argon doped with xenon and nitrogen
• Two-phase Cryogenic Avalanche Detector with electroluminescence gap operated in argon doped with nitrogen
• X-ray ionization yields and energy spectra in liquid argon
• Measurement of the ionization yield of nuclear recoils in liquid argon using a two-phase detector with electroluminescence gap
• Study of cryogenic photomultiplier tubes for the future two-phase cryogenic avalanche detector
• Further studies of proportional electroluminescence in two-phase argon
• Evolution and Recent Developments of the Gaseous Photon Detectors Technologies