Development of a TGEM-TPC for the J-PARC E15 experiment

Abstract

A Time Projection Chamber (TPC) with Thick Gas Electron Multipliers(TGEMs) has been developed for an inner tracker of the J-PARC E15experiment, a deeply-bound kaonic nuclear states search experiment. The TPC has a cylindrical design with an inner diameter of 170 mm, anouter diameter of 280 mm, and a drift length of 300 mm filled with P10gas (90:10 argon-methane) at atmospheric pressure. A TGEM is used for the amplification of the TPC in order torealize a self-supporting structure in a limited space. We use a double TGEM structure and the maximal effective gain of morethan 104 is achieved with 100 × 100 mm TGEM prototypes. Moreover, we have been developing a TGEM with graphite electrodes, which has the advantage of being fully spark-protected. From the results of our studies on the TGEM prototypes, we manufacture nonagonal TGEMs with graphite electrodes for the TPC. We have studied the performance of the amplification stage of the TPC. The gain of nonagonal TGEMs achieved more than 104 both with double- and triple-TGEM configurations. In order to realize stable operation, we have adopted the triple-TGEM configuration as the amplification stage of the TPC. The results of our recent studies of the TGEMs for the TPC are discussed.