Performance of large volume LaBr scintillation detector equipped with specially-designed shield for neutron resonance capture analysis

中性子共鳴捕獲線用大型LaBrシンチレーション検出器の遮蔽シールドの性能

土屋 晴文 ; 小泉 光生 ; 北谷 文人  ; 原田 秀郎   

Tsuchiya, Harufumi; Koizumi, Mitsuo; Kitatani, Fumito; Harada, Hideo

A large-volume (12.0 cm12.7 cm) LaBr scintillation detector equipped with a specially-designed radiation shield was evaluated for neutron resonance capture analysis at the neutron time-of-flight (TOF) facility GELINA. By using the LaBr detector with and without the shield, measurements were carried out at a 13-m TOF station with three metallic samples, namely, Ni, Cr, and Fe. In addition, Monte Carlo simulations with Geant4 were performed, and the results were compared with the measurements to analyze the observed energy spectra and TOF spectra. Energy spectra obtained with the shield showed that prompt -ray peaks emitted from each sample can be used to identify the isotopes. Moreover, the signal-to-noise ratios of resonance peaks in a TOF spectrum with the shield were enhanced 1.5-2.5 in comparison with those without the shield. Furthermore, simultaneous measurements conducted using the three samples demonstrated that the shield employed herein was indispensable for identifying impurities in a composite sample such as particle-like fuel debris.