Development of FPGA-Based Real-Time Neutron Spectrometer Using Stilbene Scintillator

Neutron/gamma ray spectrometer based on a single-crystal stilbene scintillator with the photomultiplier tube 9266B was developed and tested. Signal acquisition and real-time processing is enabled by the fast ADC with the wide-band preamplifier and the Field-Programmable Gate Array (FPGA) core. The method of n/γ event separation based on frequency gradient analysis was implemented. The paper shows the efficiency of n/γ separation delivered by the spectrometer. The energy scale calibration of gamma channel was carried out by radionuclide gamma sources. The neutron channel energy calibration was done using accelerator-based neutron sources with deuterium-deuterium and deuterium-tritium fusion reactions. Real time registration of neutron spectra and gamma spectra in different channels of spectrometer was shown when acquiring amixed neutron and gamma flux. The paper illustrates the possibility of simultaneous registrations of 2.45 MeV and 14 MeV neutrons. The energy resolution of neutron spectrometer was measured. The neutron count rate up to 2105 s−1 was demonstrated.