Real-time pulse shape discrimination for neutron scattering science using EJ-270

Abstract

A detector for neutron scattering applications utilizing the 6Li loaded pulse shape discrimination scintillator EJ-270 was developed. The detector utilises a pulse shape discrimination algorithm developed for high-count rate applications implemented in FPGA to enable real time operation. The implemented algorithm we call Tail Sum was specifically developed for high-rate thermal neutron detection and implemented into a 2 channel 500 MSps 14-bit ADC with a Xilinx Kintex 7 K325T FPGA. The detector consisted of a 48 mm diameter × 15 mm thick cylinder of EJ-270 mounted on a Hamamatsu R6231-100 PMT and an E1198-2 base at -1000 V. The performance of the system was evaluated using a moderated 241Am-Be mixed radionuclide source, a figure of merit of 1.605 ± 0.007 was measured. The γ-ray sensitivity of the system was measured using a 60Co source and found to be 3.23 × 10-6 ± 7 × 10-8. The high neutron count rate capability of the system was tested on the Emma instrument at the ISIS pulsed neutron and muon source based at the Rutherford Appleton Laboratory, a peak count rate of 5 × 105 neutrons per second was measured on a single channel and was found to have no statistically significant deviation from the expected count-rate.