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

Abstract

We report on the design, construction, and operation of a capture-gated neutron detector based on a heterogeneous scintillating structure comprising two scintillator types. A flat, 500 μm thick sheet composed of a mixture of lithium-6-fluoride capture agent, 6 LiF, and zinc sulfide phosphor, ZnS(Ag), is wrapped around scintillating polyvinyl toluene (PVT) in a form of cylinder. The 6 LiF:ZnS(Ag) sheet uses an aluminum foil backing as a support for the scintillating material and as an optical reflector, and its optical properties have been characterized independently. The composite scintillator was tested using 252 Cf, DD fusion, 137 Cs, and 60 Co sources. The intrinsic detection efficiency for neutrons from an unmoderated 252 Cf source and rejection of gammas from 137 Cs were measured to be 3.6% and 10 −6 , respectively. A figure of merit for pulse shape discrimination of 4.6 was achieved, and capture-gated spectroscopic analysis is demonstrated.

A backing detector for order-keV neutrons

“…Similarly, the outer ring WLS fibers and their corresponding SiPM comprise the outer channel. The chosen scintillator was EJ-426(ZnS:Ag/ 6 LiF) [13], a 95%-enriched 6 Li solid-state scintillator material in the form of 6 LiF dispersed in a ZnS:(Ag) scintillator matrix. The neutron is detected via the n-capture signal on 6 Li, n-capture reaction 6 Li(n, α)T produces alpha(α) and tritium(T) where the kinetic energy of the α particle is 2.05 MeV, the kinetic energy of T is 2.73 MeV.…”

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.…”