Micromegas operation in high pressure xenon: Charge and scintillation readout

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 4 × 10 2, for xenon pressures up to 5 bar and decreasing slowly above this pressure down to values somewhat above 102 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 13% at 1 bar 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 2 × 10 2 photons per primary electron at 1 bar, increasing to about 6 × 102 at 5 bar and, then, decreasing again to 2 × 10 2 at 10 bar. The readout of this scintillation by a suitable photosensor will result in higher gains but with increased statistical fluctuations. © 2011 IOP Publishing Ltd and SISSA.