NEUTRON RESPONSE FUNCTION OF A BONNER SPHERE SPECTROMETER WITH 6LiI(Eu) DETECTOR

ABSTRACT NEUTRON RESPONSE FUNCTION OF BONNER SPHERE SPECTROMETER WITH 6LiI(Eu) DETECTOR. The neutron response function of 6LiI(Eu) detector is needed to measure neutron fluence based on the count rates from a Bonner Sphere Spectrometer (BSS). The determination of response function of a BSS with 6LiI(Eu) neutron detector has been performed using Monte Carlo MCNPX code. This calculation was performed for a BSS using scintillation detector of 4 mm × 4 mm 6LiI(Eu) which was placed at the center of a set of polyethylene spheres i.e bare, 2", 3", 5", 8", 10", and 12" diameters. The BSS response functions were obtained for neutron energy range of 1x10-9 MeV - 1x102 MeV in 111 energy bins and each value had an uncertainty of less than or equal to 2 %. The calculation results were compared with two response functions reported in a IAEA document of Technical Reports Series 403 (TRS-403) and calculated by Vega-Carrillo, et al. and also validated by direct measurement of 252Cf neutron spectra. The result show that the calculated BSS spectra are quite close to the measured spectra with a differrence of 3%.