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

Abstract To study the β -delayed neutron decay of nuclei far from β stability line, a new β -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 β particles, a double-sided silicon detector is sandwiched between two thin plastic scintillators, which constitute the implantation and β detection array. According to the test measurements with radioactive ion beams, this detection system has a high β 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 β -delayed neutron decay of nuclei with very low beam intensity feasible.