Identification Of Fusion Reaction With Active Target Detectors

Fusion reactions between neutron-rich nuclei are expected to be an energy source for the ignition of carbon explosive burning in superbursts.It is difficult to operate a measurement with such radioactive beams in the astrophysical energy region.In such case,the active target technique was developed recently for its high efficiency so as to probe into radioactive beam reactions.This thesis mainly explore the capability of active target detectors to identify fusion reaction events and the minimum limit of energy for measuring fusion cross sections using Geant4 simulations.There are two parts.Part one involves the investigation of the features of elastic scattering and fusion events with the readout pad adopted from Argonne'MUSIC.The reaction is ¹³C+¹²C in 2×10⁴ Pa methane and energy for beam particles is E_cm=13.6 MeV.There have been four methods developed for discriminating between elastic scattering and fusion reactions:track lengths after reaction,double hits on the read-out plane,a plateau following an energy peak and multiple signals on electron drifting direction.The applicability and constraint of these methods are thoroughly discussed and then cross sections resulted from misjudgments of these methods are calculated.In the end,the discrimination of fusion reaction and elastic scattering are analyzed under the circumstance of 10⁴ Pa gas pressure and E_cm=5.3 MeV particle energy.Part two introduces an experiment measuring fusion cross sections of ¹⁶O+⁴⁰Ar with a48-channel TPC using the same readout pad structure as above and focuses on the ability to discriminate fusion reaction from elastic scattering events.