Comparison of Several Monte Carlo Codes with Neutron Deep Penetration Experiments

We performed a systematic benchmark study of several Monte Carlo codes for neutron deep penetration experiments at 0 deg, which were previously performed using 40-, 65-, and 137-MeV quasi-monoenergetic neutrons and using continuous-energy neutrons up to 400 MeV. Neutron energy spectra behind shields and the attenuation lengths of the neutron flux are compared between the experiments and the calculations. All calculations generally well reproduce the energy spectra and the attenuation lengths measured in the experiments. The attenuation length obtained as a function of the incident neutron energy in this study rapidly increases with the incident energy.