Cryogenic Gaseous Photomultiplier for Position Reconstruction of Liquid Argon Scintillation Light

TL;DR

This paper reports the first tests of a cryogenic gaseous photomultiplier using Thick GEM structures for precise gamma-ray position reconstruction in liquid Argon, demonstrating high gain, efficiency, and sub-100 micron resolution at room temperature.

Contribution

It introduces a novel cryogenic gaseous photomultiplier with Thick GEMs for liquid Argon applications, showing promising performance and structural integrity at cryogenic temperatures.

Findings

Achieved gain of 8×10^5 per photoelectron

Demonstrated position resolution better than 100 μm

Successfully tested structural integrity at cryogenic temperatures

Abstract

Presented here are first tests of a Gaseous Photomultiplier based on a cascade of Thick GEM structures intended for gamma-ray position reconstruction in liquid Argon. The detector has a MgF$_2$ window, transparent to VUV light, and a CsI photocathode deposited on the first THGEM. A gain of $8\cdot10^{5}$ per photoelectron and $\sim100\%$ photoelectron collection efficiency are measured at stable operation settings. The excellent position resolution capabilities of the detector (better than 100 $\mu$m) at 100 kHz readout rate, is demonstrated at room temperature. Structural integrity tests of the detector and seals are successfully performed at cryogenic temperatures by immersing the detector in liquid Nitrogen, laying a good foundation for future operation tests in noble liquids.