Development of a time projection chamber for J-PARC hadron physics program

Abstract

A time projection chamber (HypTPC) has been newly developed for the various hadron physics experiments at J-PARC. The design of HypTPC was carefully considered to cope with the J-PARC high intensity beam. The triple-layered GEM has been adopted as a signal amplification and the gating grid plane for an ion backflow suppression. The octagonal drift volume is defined by the cathode plane and the field cage structure with the height of 55 cm. A target is located inside the drift volume in order to have a large acceptance. The GET (General Electronic System for TPCs) is utilized for the data acquisition. The HypTPC was first commissioned with 230 MeV proton beam at HIMAC. The obtained position resolution is 400–700 µm, which gives the expected resolution of 230–300 µm under a magnetic field of 1 T. We have confirmed the high rate capability of the TPC up to 1 MHz with a good suppression of the ion backflow under the gate operation.