Active Target Time Projection Chamber (TPC) for Nuclear Astrophysics Experiments

The fusion reaction of neutron-rich nuclei occurring in the neutron star crust is considered to be the important heating process in neutron stars and X-ray super burst. Limited by the intensity of radioactive beams and the complexity of reaction mechanism, experimental data so far are rare and can not constrain relevant theoretical model effectively. The time projection chamber (TPC) based on the active target technique works with the detection gas as the target, which can record all the tracks including the incident particle and charged particles from the reaction occurring in the detection gas. TPC has approximately 4\pi solid angle acceptance and 3D track reconstruction capabilities, which can significantly improve detection efficiency, making TPC a powerful device to measure the low cross sections of fusion reactions. A 240-channels active target TPC has been developed. The test experiment of ¹⁶N+¹²C fusion measurement was carried out and validated the feasibility of measuring the fusion reaction cross section by active target TPC. In order to obtain more accurate reaction tracks to identify fusion events, a 1024-channels TPC was constructed and then commissioned by measuring the ¹²C+¹²C fusion reaction cross section at energies around coulomb barrier. The preliminary result is in good agreement with the existing experimental data.