High efficiency fast neutron detectors based on inorganic scintillators

• Published in: 2014 IEEE Nuclear Science Symposium and Medical Imaging Conference (NSS/MIC) pp. 1 - 6
• Main Authors: Ryzhikov, V.D., Naydenov, S.V., Onyshchenko, G.M., Piven, L.A., Pochet, T., Smith, C.F.
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01-11-2014
• Subjects: Crystals; Detectors; Lead; Neutrons; Scattering; Sensitivity; Software
• DOI: 10.1109/NSSMIC.2014.7431165

The possibility was studied of using highly efficient heavy inorganic oxide solid-state scintillation detectors for the detection of mixed gamma-neutron radiation. In the detection of gamma-neutron radiation, the gamma detection efficiency for such detectors reaches 70-80%, with neutron detection efficiency not less than 40%. Detection efficiencies were measured for the heavy oxide scintillator crystals CWO (CdWO 4 ), ZWO (ZnWO 4 ), BGO (Bi 4 Ge 3 O 12 ), GSO (Gd 2 SiO 5 ), YSO:Ce (Y 2 SiO 5 :Ce) and LuAG:Ce (Lu 3 Al 5 O 12 :Ce). For comparison purposes, the scintillators NaI:Tl, LiI:Eu, ZnSe(Te), CsI(Tl) were also considered. The dependencies of detection efficiency on Zeff, thickness and area of the detector were obtained. To eliminate the effects of accompanying gamma-radiation in the detection of neutrons, suppression of gamma-background was studied using lead protection of 2-40 mm thickness as well as a protection screen consisting of a cylindrical ring of BGO with an internal diameter of 40 mm and an external diameter 60 mm surrounding a cylindrical CWO scintillator detector of dimension 40×40 mm. Suppression of the gamma background by factors of 2-10 was achieved with passive protection. With the BGO screen in an active mode, gamma background suppression reached 10 3 . Also, an original "windows" method [1] of data analysis was proposed for mathematical processing of gamma background, with appropriate software, allowing us to reach neutron/gamma ratios from 10 5 to 10 7 .