A β-delayed neutron detection system working with the continuous beam mode

摘要

To study the beta-delayed neutron decay of nuclei far from beta stability line, a new beta-delayed neutron detection system working with the continuous beam mode has been built at Peking University and tested with radioactive ion beams. To get fast timing signal for neutron Time-of-Flight (ToF) measurement and good spatial correlation between the implanted particles and the subsequent beta particles, a double-sided silicon detector is sandwiched between two thin plastic scintillators, which constitute the implantation and beta detection array. According to the test measurements with radioactive ion beams, this detection system has a high beta coincident detection efficiency of 30.7(5)% with much less disturbance from other unstable nuclei and the random background. After the time-walk correction and the flight path calibration, good energy resolution based on neutron ToF measurement can be obtained. The properties of this detection system make the study of beta-delayed neutron decay of nuclei with very low beam intensity feasible.