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

• Published in: Journal of instrumentation 2022-08, Vol.17 (8), p.P08011
• Main Authors: Richards, S.A., Helbsy, W., Sykora, G.J., Wheater, R.M., Wilson, M.D.
• Format: Article
• Language: English
• Subjects: Algorithms; Detector control systems (detector and experiment monitoring and slow-control systems, architecture, hardware, algorithms, databases); Diameters; Digital signal processing (DSP); Discrimination; Figure of merit; Neutron detectors (cold, thermal, fast neutrons); Neutron scattering; Neutrons; Pulse shape; Radioisotopes; Real time operation; Scintillation counters; Scintillators, scintillation and light emission processes (solid, gas and liquid scintillators); Sensors; Thermal neutrons
• ISSN: 1748-0221; 1748-0221
• DOI: 10.1088/1748-0221/17/08/P08011

A detector for neutron scattering applications utilizing the 6 Li 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 241 Am-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 60 Co 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 × 10 5 neutrons per second was measured on a single channel and was found to have no statistically significant deviation from the expected count-rate.