On the operation of a Micropattern Gaseous UV-Photomultiplier in Liquid-Xenon

TL;DR

This paper demonstrates the operation of a UV-sensitive gaseous photomultiplier coupled to liquid xenon, achieving high gains and detecting scintillation signals induced by alpha particles at cryogenic temperatures.

Contribution

It presents the first measurement of liquid xenon scintillation signals using a gaseous photomultiplier with novel multi-stage amplification structures at cryogenic temperatures.

Findings

Achieved gains of 10^4 with double-THGEM detector.

First detection of liquid xenon scintillation signals with a double-THGEM GPM.

Demonstrated operation in cryogenic gas mixtures at 173 K.

Abstract

Operation results are presented of a UV-sensitive gaseous photomultiplier (GPM) coupled through a MgF2 window to a liquid-xenon scintillator. It consisted of a reflective CsI photocathode deposited on top of a THick Gaseous Electron Multiplier (THGEM); further multiplication stages were either a second THGEM or a Parallel Ionization Multiplier (PIM) followed by a MICROMEsh GAseous Structure (MICROMEGAS). The GPM operated in gas-flow mode with non-condensable gas mixtures. Gains of 10^4 were measured with a CsI-coated double-THGEM detector in Ne/CH4 (95:5), Ne/CF4 (95:5) and Ne/CH4/CF4 (90:5:5), with soft X-rays at 173 K. Scintillation signals induced by alpha particles in liquid xenon were measured here for the first time with a double-THGEM GPM in He/CH4 (92.5:7.5) and a triple-structure THGEM/PIM/MICROMEGAS GPM in Ne/CH4 (90:10) with a fast-current preamplifier.