Attenuation of Fast Neutrons in Ilmenite Concretes

Abstract

Energy distributions of fast neutrons (>0.5 MeV) transmitted through slabs of normal and high density ilmenite concretes, obtained by time of flight methods, are presented for concrete thicknesses increasing in steps of 7.6cm from 0 to 46cm. The incident spectrum consisted of a photoneutron continuum from aluminium irradiated with 35 MeV bremsstrahlung, and was thus of somewhat higher mean neutron energy than a typical fission spectrum.The measured distributions are in satisfactory agreement with the results of a Monte Carlo simulation, and results from the latter are used to extrapolate the measured data to greater thicknesses and other ilmenite concrete densities.