Neutron and gamma ray discrimination for CLYC using normalized cross correlation analysis

The reduced availability of ³He is a motivation for developing alternative neutron detectors. ⁶Li-enriched CLYC (Cs₂LiYCl₆), a scintillator, is a promising candidate to replace ³He. The neutron and gamma ray signals from CLYC have different shapes due to the slower decay of neutron pulses. Some of the well-known pulse shape discrimination techniques fail to produce the desired results in a mixed radiation environment, particularly at high event rates. In the work presented here, we have applied a normalized cross correlation (NCC) approach to real neutron and gamma ray pulses produced by exposing CLYC scintillators to a mixed radiation environment generated by ¹³⁷Cs and ²⁵²Cf/AmBe at different event rates. The cross correlation analysis produces distinctive results for measured neutron pulses and gamma ray pulses when they are cross correlated with reference neutron and/or gamma templates even at high event rates where the pileup is significant. With the NCC analysis shown to be a valid approach, efforts are continuing to develop a suitable algorithm to automatically process the NCC results to not only count the pulses but also to provide rudimentary neutron and gamma energy spectra. Ultimately, the technique will be implemented in an FPGA.