Neutron-sensitive ZnS/BO ceramic scintillator detector as an alternative to a He-gas-based detector for a plutonium canister assay system

Nakamura, Tatsuya  ; Ozu, Akira  ; To, Kentaro  ; Sakasai, Kaoru  ; Suzuki, Hiroyuki; Honda, Katsunori; Birumachi, Atsushi; Ebine, Masumi ; Yamagishi, Hideshi*; Takase, Misao; Haruyama, Mitsuo; Kureta, Masatoshi   ; Soyama, Kazuhiko  ; Nakamura, Hironobu ; Seya, Michio

A neutron-sensitive ZnS/BO ceramic scintillator detector was developed as an alternative to a He-gas-based detector for use in a plutonium canister assay system. The detector has a modular structure, with a flat ZnS/BOceramic scintillator strip that is installed diagonally inside a light-reflecting aluminium case with a square cross section. The prototype detectors, which have a neutron-sensitive area of 30 mm 250 mm, exhibited a sensitivity of 21.7-23.4 0.1 cpsnv for thermal neutrons, a Cs -ray sensitivity of 1.1-1.9 0.2 10 and a count variation of less than 6% over the detector length. A trial experiment revealed a temperature coefficient of less than -0.24 0.05% / C over the temperature range of 20-50C.