Tests of Micro - Pattern Gaseous Detectors for Active 1 Target Time Projection Chambers in nuclear physics

9 Active target detection systems, where the gas used as the detection medium 10 is also a target for nuclear reactions, have been used for a wide variety of 11 nuclear physics applications since the eighties. Improvements in MPGD (Mi12 cro Pattern Gaseous Detectors) and in micro-electronics achieved in the last 13 decade permit the development of a new generation of active targets with 14 higher granularity pad planes that allow spatial and time information to be 15 determined with unprecedented accuracy. A novel active target and time 16 projection chamber (ACTAR TPC), that will be used to study reactions 17 and decays of exotic nuclei at facilities such as SPIRAL2, is presently un18 der development and will be based on MPGD technology. Several MPGD 19 (Micromegas and Thick GEM) coupled to a 2×2 mm pixellated pad plane 20 have been tested and their performances have been determined with differ21 ent gases over a wide range of pressures. Of particular interest for nuclear 22 physics experiments are the angular and energy resolutions. The angular 23 resolution has been determined to be better than 1◦ FWHM for short traces 24 of about 4 cm in length and the energy resolution deduced from the particle 25 range was found to be better than 5% for 5.5 MeV α particles. These per26 formances have been compared to Geant4 simulations. These experimental 27 results validate the use of these detectors for several applications in nuclear 28 physics. 29