Studies of charging up in THGEMs

Abstract

The time-dependent variation of detector response in MPGDs, especially THGEMs, is a challenging problem that has been attributed to the charging up and charging down processes of insulating materials present in these detector. Experimental studies of stabilization of gain with time due to these phenomena under various experimental conditions are presented in this paper. Effects of sources with varying irradiation rates on the gain saturation process have been studied. Low-rate source shows two-step gain stabilization phenomena, one short-term saturated gain, another long-term saturated gain, whereas high-rate source shows a single-step gain saturation. While this two-step stabilization has been attributed to the charging up of the rim by earlier studies, its effect seems to be subdued for high-rate irradiation according to the observations presented here.