A HIGH-EFFICIENCY METHOD OF DETECTION OF FAST NEUTRONS FOR DETECTION SYSTEMS OF FISSIONABLE RADIOACTIVE MATERIALS

Comparative measurements and detection efficiency analysis were carried out for fast neutrons from 239Pu-Be source in a broad energy range of En ∼ 0.1 ÷ 10 MeV using oxide scintillators BiGe3O12, Gd2SiO5, CdWO4, ZnWO4, ZnSe(Te,O) as well as NaI(TI), Csl(TI) and 6LiI(Eu). The experimentally obtained fast neutron detection efficiency by heavy inorganic (oxide) scintillators (Z ≥ 50) reaches ∼ 40-50%. One of the most probable mechanisms ensuring such high efficiency of fast neutron by oxide scintillators is the inelastic scattering reaction (n,n'γ) . It is concluded that heavy oxide scintillators, which at the same time are efficient gamma-detector, allow creation of a highly efficient gamma-neutron detector, which ensures high efficiency of detection of fissionable radioactive materials./i