Micromegas operation in high pressure xenon: charge and scintillation readout

TL;DR

This study investigates the performance of Micromegas detectors in high-pressure xenon, focusing on charge gain, energy resolution, and scintillation yield, revealing pressure-dependent behaviors relevant for advanced particle detection applications.

Contribution

It provides the first detailed characterization of Micromegas operation in pure xenon at pressures up to 10 bar, including charge gain, energy resolution, and scintillation yield measurements.

Findings

Maximum charge gain around 400 at pressures up to 5 bar

Energy resolution increases from 12% at 1 bar to 32% at 10 bar

Scintillation yield peaks at 5 bar with about 600 photons per electron

Abstract

The operational characteristics of a Micromegas operating in pure xenon at the pressure range of 1 to 10 bar are investigated. The maximum charge gain achieved in each pressure is approximately constant, around 4x10^2, for xenon pressures up to 5 bar and decreasing slowly above this pressure down to values somewhat above 10^2 at 10 bar. The MM presents the highest gains for xenon pressures above 4 bar, when compared to other micropattern gaseous multipliers. The lowest energy resolution obtained for X-rays of 22.1 keV exhibits a steady increase with pressure, from 12% at 1bar to about 32% at 10 bar. The effective scintillation yield, defined as the number of photons exiting through the MM mesh holes per primary electron produced in the conversion region was calculated. This yield is about 2x10^2 photons per primary electron at 1 bar, increasing to about 6x10^2 at 5 bar and, then, decreasing again to 2x10^2 at 10 bar. The readout of this scintillation by a suitable photosensor will result in higher gains but with increased statistical fluctuations.