Experimental and computed spectra of neutrons and photons emitted from spherical iron models with a 252Cf source at the center

Series of experiments and calculations in which the spectra of neutrons and photons emitted from 20, 40, 50, 60, 70, and 100 cm in diameter spherical models with a 252Cf source at the center are studied are described. The neutron spectra are measured with spectrometers based on stilbene and a hydrogen counter and the photon spectra are measured with spectrometers based on stilbene and a Si(Li) detector. The calculations are performed using the ROZ-6 computer program and the BNAB-78 28-group neutron constants library. The experimental fluxes of >0.8 MeV neutrons are, for the most part, greater than the computed values, and the fluxes of >0.35 MeV photons are also greater than the computed values. The differences reach a factor of 2–3. The data obtained show that the the cross sections for elastic and inelastic neutron scattering and radiative capture of neutrons need to be changed, leaving the total cross sections for the interaction of neutrons with iron in the constants library tested unchanged.