Recent advances with a hybrid micro-pattern gas detector operated in low pressure H2 and He, for AT-TPC applications

In view of a possible application as a charge-particle track readout for an Active-Target Time Projection Chamber (AT-TPC), the operational properties and performances of a hybrid Micro-Pattern Gaseous Detector (MPGD) were investigated in pure low-pressure Hydrogen (H 2 ) and Helium (He). The detector consists of a MICROMEsh GAseous Structure (MICROMEGAS) coupled to a two-cascade THick Gaseous Electron Multiplier (THGEM) as a pre-amplification stage. This study reports the effective gain dependence of the hybrid-MPGD at relevant pressure (in the range of 200-760 torr) for different detector arrangements. The results of this work are relevant in the field of avalanche mechanism in low-pressure, low-mass noble gases, in particularly for applications of MPGD end-cap readout for active-target Time Projection Chambers (TPC) in the field of nuclear physics and nuclear astrophysics.