Performance of a MICROMEGAS-based TPC in a high-energy neutron beam

TL;DR

This study evaluates the stability and performance of a MICROMEGAS-based TPC in high-energy neutron beams, revealing how neutron-induced reactions affect discharges and how gas mixture adjustments can improve stability.

Contribution

It provides new insights into MICROMEGAS TPC operation under neutron irradiation and suggests optimal gas mixture strategies for enhanced stability in such environments.

Findings

Neutron-induced reactions cause discharges in MICROMEGAS TPCs.

Increasing quench gas percentage improves stability.

Lower pressures generally enhance detector stability.

Abstract

The MICROMEGAS (MICRO-MEsh GAseous Structure) charge amplification structure has found wide use in many detection applications, especially as a gain stage for the charge readout of Time Projection Chambers (TPCs). Here we report on the behavior of a MICROMEGAS TPC when operated in a high-energy (up to 800 MeV) neutron beam. It is found that neutron-induced reactions can cause discharges in some drift gas mixtures that are stable in the absence of the neutron beam. The discharges result from recoil ions close to the MICROMEGAS that deposit high specific ionization density and have a limited diffusion time. For a binary drift gas, increasing the percentage of the molecular component (quench gas) relative to the noble component and operating at lower pressures generally improves stability.