Developments of a LaBr scintillation detector system for neutron resonance densitometry (NRD)

Koizumi, Mitsuo ; Tsuchiya, Harufumi ; Kitatani, Fumito  ; Harada, Hideo   ; Takamine, Jun ; Kureta, Masatoshi   ; Seya, Michio; Kimura, Atsushi   ; Iimura, Hideki  ; Becker, B.*; Kopecky, S.*; Mondelaers, W.*; Schillebeeckx, P.*

Neutron resonance densitometry (NRD) has been proposed as a method to quantify the amount of special nuclear materials in particle-like debris of melted fuel. The requirements of a -ray detector system for the NRD measurements are: (1) good energy resolution to identify elements (2) fast response not to be suffocated by the radiation from debris samples and (3) good signal to noise ratio. The quantification of B is considered to be the most important for NRD because of its very large neutron cross-sections. However, the Compton peak of the rays from Cs, which is probably the strongest radioactivity in debris, overlaps the B peak; and it makes the measurements difficult. We, therefore, designed a well-type LaBr scintillation spectrometer to reduce the Compton peak. The progress of the research and development of the spectrometer is reported.