Measurements and calculations of neutron spectra modified by iron slabs bombarded by neutrons with energies up to 14 MeV.

Neutron spectra behind iron slabs of different thicknesses have been measured in the energy range from 1.6 to 14 MeV using a proton recoil spectrometer and 2H(d, n)3He and 9Be(d, n)10B neutron sources. The measured results have been compared with the predicted ones using the three dimensional Monte Carlo code MCNP 4A and pointwise cross sections from the ENDF/B-IV and ENDF/B-VI data files. The results show that the ENDF/B-IV calculations are in better agreement with the experiment than those obtained by using the ENDF/B-VI cross section data.