Study of infrared scintillations in gaseous and liquid argon - Part I: methodology and time measurements

TL;DR

This paper presents a new methodology for measuring near-infrared scintillations in gaseous and liquid argon using Geiger-mode APDs, enabling detailed time and yield measurements crucial for cryogenic detector applications.

Contribution

It introduces a novel approach employing GAPDs in single photoelectron mode for NIR scintillation yield measurement at cryogenic temperatures.

Findings

Measured time structure of NIR scintillations in gaseous and liquid argon.

Quantified light yield for primary and secondary scintillations.

Demonstrated the method's applicability for cryogenic detector development.

Abstract

A methodology to measure Near Infrared (NIR) scintillations in gaseous and liquid Ar, using Geiger-mode APDs (GAPDs) sensitive in the NIR and pulsed X-ray irradiation, is described. This study has been triggered by the development of Cryogenic Avalanche Detectors (CRADs) with optical readout in the NIR using combined THGEM/GAPD multiplier, which may come to be in demand in coherent neutrino-nucleus scattering and dark matter search experiments. A new approach to measure the NIR scintillation yield at cryogenic temperatures has been developed, namely using GAPDs in single photoelectron counting mode with time resolution. The time structure of NIR scintillations and their light yield were measured both for primary scintillations and that of secondary at moderate electric fields (electroluminescence), in gaseous and liquid Ar.