Double differential distribution, attenuation lengths and source terms for proton accelerator shielding

Double differential distributions of neutrons produced by 100, 150, 200, 250 and 400 MeV protons stopped in thick iron and soft issue targets were calculated by two Monte Carlo codes, FLUKA and LCS, from 0 degree (forward shielding) to 180 degrees. The results are compared with calculated and experimental data available in the literature. The attenuation in ordinary concrete of the dose equivalent due to neutrons and other particles was calculated. The contribution due to photons and protons was found to range from a few percent up to 50 % of the total dose equivalent. Source terms and attenuation lengths are given as a function of energy and emission angle. (authors)