A combined spectrometric detector of fast neutrons

Abstract

A combined spectrometric detector consisting of two subdetectors for fast and thermal neutrons has been developed. The fast neutron detector is a total absorption detector with a polystyrene-based scintillator generating a signal proportional to the absorbed energy of a fast neutron. The thermal neutron detector based on a scintillator in the form of a thin screen detects neutrons that have lost almost all their energy in the first detector and have been thermalized. The electronics of the combined detector operates in coincidence: if a neutron has been detector by the thermal neutron detector, the signal from the fast neutron detector participates in the formation of the amplitude spectrum within a predetermined time interval (fast neutron moderation time). The methods for reconstructing the neutron spectrum by the spectrum recorded using the combined detector are considered. The measured neutron spectra from various sources are presented.

Design of a mobile neutron spectrometer for the Laboratori Nazionali del Gran Sasso (LNGS)

“…To the best of our knowledge, commercial production has not been launched to date. Plastic scintillator-based capture-gated neutron spectrometers incorporating 6 LiF/ZnS(Ag) scintillators [48,49] and 6 Li-enriched glasses [50,51] have been previously demonstrated. Neutron capture pulses generated in the 6 Li-doped medium generally have longer tails than the background pulses produced via Compton scattering of gamma rays in the plastic scintillator.…”

Development and operation of a 6LiF:ZnS(Ag)—scintillating plastic capture-gated detector

“…A heterogeneous design using 6 LiF:ZnS(Ag) scintillator sheets has been recently demonstrated in a coincidence design and used to resolve the energy spectra of incident fast neutrons [23]. That design requires the use of two photodetectors, and only incorporates the 6 LiF:ZnS(Ag) on one edge of the detector, thereby sacrificing neutron detection efficiency in order to achieve fast neutron spectroscopy.…”