Two-phase Cryogenic Avalanche Detector with electroluminescence gap operated in argon doped with nitrogen

TL;DR

This study demonstrates a two-phase cryogenic avalanche detector with an electroluminescence gap in argon doped with nitrogen, achieving high sensitivity to X-ray signals, relevant for dark matter and neutrino detection.

Contribution

It introduces a novel two-phase cryogenic avalanche detector with an electroluminescence gap operated in nitrogen-doped argon, enhancing detection sensitivity.

Findings

Detector sensitivity of 9 and 16 photoelectrons/keV at 23 and 88 keV

Effective N$_2$ doping level of 49±7 ppm

High electron lifetime and EL yield in the detector

Abstract

A two-phase Cryogenic Avalanche Detector (CRAD) with electroluminescence (EL) gap, operated in argon doped with a minor (49$\pm$7 ppm) admixture of nitrogen, has been studied. The EL gap was optically read out using cryogenic PMTs located on the perimeter of the gap. We present the results of the measurements of the N$_2$ content, detector sensitivity to X-ray-induced signals, EL gap yield and electron lifetime in the liquid. The detector sensitivity, at a drift field in liquid Ar of 0.6 kV/cm, was measured to be 9 and 16 photoelectrons recorded at the PMTs per keV of deposited energy at 23 and 88 keV respectively. Such two-phase detectors, with enhanced sensitivity to the S2 (ionization-induced) signal, are relevant in the field of argon detectors for dark matter search and low energy neutrino detection.