Efficiency Calibration Of Neutron Detector Array For β-Decay Of Exotic Nuclei

Beta decay of exotic nuclei provides one of the primary tools for investigation of nuclear structure as well as of weak interaction. The largeβ-decay energy for such nuclei often leads to the population of particle-unbound states in the daughter nuclei. As a result,β-delayed particle emission is frequently the dominant decay mode. For neutron rich nuclei, most of the emitted particles are neutrons. In order to study the beta-delayed neutron decay, the Neutron Detector Array was built in Peking University. And using this Neutron Detector Array , the beta-decay of 21N experiment was carried-out in LanZhou. And the research of the in-beam efficiency calibration of the Neutron Detector Array using the 17N and 16C beam in this experiment was introduced in this paper.According to the experiment results and Monte Karlo simulation, the intrinsic detection efficiency for the Neutron Ball is about 25% at 1.5-2.5MeV, and decreases quickly below 1.5 MeV. The ball's detection threshold is about 700keV. For the neutron wall, the detection threshold is about 300keV and the intrinsic detection efficiency is about 40% at 1 MeV and still high at low energy region, 30% at 0.383MeV.The efficiency of the ball is comparable to the similar devices in the world and the wall has low detection threshold that can make the whole neutron detection array have low detection threshold. So the neutron detection from low energy to high can be realized using the neutron detection array of Peking University.With these detector arrays, we can carry out the experiments for investigatingβ- decay characteristics of the neutron abundant nuclei.