Characterization of the neutron/γ-ray discrimination performance in an EJ-301 liquid scintillator for application to prompt fission neutron spectrum measurements at CSNS

The FIssion Neutron spectrum Detector Array (FINDA) has been designed for measurement of prompt fission neutron spectrum on the Back-n beam line at the China Spallation Neutron Source (CSNS). In order to test the neutron-γ discrimination performance of the EJ301 scintillator that will be used as a detector unit in the FINDA, a comparative study using three conventional digital pulse shape discrimination (PSD) methods has been carried out. An Am–Be source has been used to generate the mixed neutron-γ radiation and the waveform data has been obtained with a fast digitizer. Pulse interpolation, baseline restoration and pulses pile-up rejection have been applied for digital pulse processing. Charge comparison (CC) method and simplified charge comparison(SCC) method show a better capability of neutron-γ discrimination than rise time comparison(RTC) method over the entire energy range. Rise time comparison method needs a very fast digitizer or pulse interpolation to improve the PSD ability. The analysis of neutron-γ discrimination performance of the EJ301 scintillator provides a strong technical support for fast neutron measurement using the FINDA at CSNS.