| Heavy-ion fusion reactions play crucial roles in stellar evolution and nucleosynthe-sis in the universe,including stable nuclear reactions such as carbon fusion in massive stars,and unstable nuclear reactions incurred by the neutron-rich isotopes of oxygen or neon in the crust of neutron stars.Limited by the tiny cross section,large background,and available beam intensity,it is very challenging to study these reactions at stellar energies.A lack of experimental data near astrophysical energy regions brings great uncertainty to theoretical calculations of the reaction rates,which makes stellar model predictions highly uncertain.Therefore,it is necessary to develop techniques to study these reactions.The active target Time Projection Chamber（TPC）has been developed and widely used in nuclear physic experiments in the past twenty years.TPC has many advantages,such as the ability of 3D tracks reconstruction,high position resolution,low threshold,nearly 4detection efficiency.It offers a new opportunity to study the difficult reactions at stellar energies.To study the fusion reactions at stellar energies,we developed a 1024-channel TPC prototype named MATE（Multi-purpose Active target Time projection chamber for nu-clear astrophysics and exotic beam Experiments）.The present work shows that TPC provides a new opportunity for accurate and precise measurements of the important as-trophysical nuclear reactions near the Gamow windows.In this thesis,the framework of the TPC prototype is introduced at first,including the detector itself and the GET electronics.To decode and preprocess the raw data,we have developed the software Nimp Root.The main algorithms of Nimp Root are described in the thesis.Then a se-ries of performance tests were performed,including GET gain fluctuation,TPC tracks,range and energy resolution,and gain uniformity,and the corresponding results are ob-tained.Finally,two kinds of fusion experiments are performed using MATE as a track-ing detector and an active target,respectively:12C+12C fusion reaction at low energy region under a high-intensity beam,and12C+12C fusion reaction at the energy region around the coulomb barrier under a low-intensity beam.In the first experiment,by us-ing the tracking ability of the TPC,the background was suppressed significantly,and the charged particles produced during the12C+12C reaction are clearly identified.The experiment illustrates the unique advantages of TPC in the detection of rare events.In the second experiment,by using the 3D track information,the fusion events are clearly identified and selected,and then the excitation function was obtained in a relatively short period using limited beam intensity,demonstrating its great potential in exotic beam experiments.The preliminary results of the19O+12C fusion reaction experiment are also performed. |
