Development of the GEM‐MSTPC for studies of astrophysical nuclear reaction rates

We have developed an active‐target type gas‐detector, a Gas Electron Multiplier Multiple‐Sampling and Tracking Proportional Chamber (GEM‐MSTPC) operating with low‐pressure He‐base mixed gas, where He is used as a target for studies of astrophysical nuclear reaction rates. Different kinds of 400 μm thick GEMs were examined. The gain stability was examined with a configuration of GEMs of 400 μm in thickness fabricated in different ways, against the injection rate of low‐energy heavy ions of 105 particles per second. The gain of GEM with Cu electrodes coated by Au was observed to be stable up to the injection rate of 105 particles per second.