Gas-gain study of standard CERN GEM and 400‐μm-thick400‐μm-thick Thick GEM in low-pressure He/CO2 mixed gas

We have evaluated and compared the performances of a 50‐μm-thick50‐μm-thick CERN GEM and a 400‐μm-thick400‐μm-thick Thick GEM in low-pressure He/CO2 (90%/10%) mixed gas. In particular, the empirical gas gains of the standard CERN GEM and the Thick GEM have been measured and investigated.