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.
@article{arxiv.1712.01830,
title = {Performance of a MICROMEGAS-based TPC in a high-energy neutron beam},
author = {Lucas Snyder and Brett Manning and Nathaniel S. Bowden and Jeremy Bundgaard and Robert J. Casperson and Daniel A. Cebra and Timothy Classen and Dana L. Duke and Joshua Gearhart and Uwe Greife and Christian Hagmann and Michael Heffner and David Hensle and Daniel Higgins and Donald Isenhower and Jonathan King and Jennifer L. Klay and Verena Geppert-Kleinrath and Walter Loveland and Joshua A. Magee and Michael P. Mendenhall and Samuele Sangiorgio and Brandon Seilhan and Kyle T. Schmitt and Fredrik Tovesson and Rusty S. Towell and Nicholas Walsh and Shon Watson and Liangyu Yao and Walid Younes},
journal= {arXiv preprint arXiv:1712.01830},
year = {2017}
}