Neutron generator burst timing measured using a pulse shape discrimination plastic scintillator with silicon photomultiplier readout

Abstract

An EJ-299-34 plastic scintillator with siliconphotomultiplier (SiPM) readout was used to measure the fast neutron outputof a pulsed Thermo-Fisher A-325 Deuterium-Tritium sealed tube neutrongenerator (STNG). The SiPM signals were handled by a prototype digital pulseprocessing system, based on a free-running analogue to digital converterfeeding a digital signal processor (DSP). Pulse shape discrimination wasused to distinguish between detected fast-neutrons and gammas. Pulsedetection, timing, energy and shape were all processed by the DSP inreal-time.The time-dependency of the neutron output of the STNG was measured forvarious pulsing schemes. The switch-on characteristics of the tube stronglydepended on the operating settings, with the delay between pulse turn-on andthe production of neutrons ranging between 13 μs to 74 μs for thetested pulse rates and duty cycles. This work will facilitate theoptimization and modeling of apparatus that use the neutron generator'spulsing abilities.