Microbulk Micromegas in non-flammable mixtures of argon and neon at high pressure

TL;DR

This study systematically characterizes microbulk Micromegas detectors in high-pressure argon and neon mixtures, demonstrating high gains and competitive energy resolution, with potential applications in high-pressure time projection chambers.

Contribution

It provides detailed measurements of gain, electron transmission, and energy resolution of Micromegas in high-pressure argon and neon mixtures, showing stable high gains without pressure-related degradation.

Findings

Maximum gains above 1.7e3 in argon and 1.7e4 in neon at high pressures

Energy resolution of 10.8% at 1 bar in argon, degrading to 15.6% at 10 bar

Energy resolution of 8.3% at 5 bar in neon, degrading to 15.0% at 10 bar

Abstract

We report on a systematic characterization of microbulk Micromegas readouts in high-pressure Ar+1%iC4H10 and Ne+2%iC4H10 mixtures. Experimental data on gain, electron transmission and energy resolution are presented for a wide range of drift and amplification voltages and pressures from 1 bar to 10 bar for argon and from 5 bar to 10 bar in neon, in steps of 1 bar. Maximum gains higher than 1.7e3 (1.7e4) in argon (neon) are measured for all pressures, remarkably without the significant decrease with pressure typically observed in other amplification structures. A competitive energy resolution at 22.1 keV, but with a slight degradation with pressure, is observed:from 10.8% at 1 bar to 15.6% FWHM at 10 bar in argon and from 8.3% at 5 bar to 15.0% FWHM at1 10 bar in neon. The experimental setup, procedure and the results will be presented and discussed in detail. The work is motivated by the TREX-DM experiment, that is operating in the Laboratorio Subterr\'aneo de Canfranc with the mentioned mixtures, although the results may be of interest for other applications of time projection chambers at high pressures.