Calculations of Nucleon Emission and Energy Deposition of Spallation Neutron Sources Induced by Intermediate Energy Protons

Monte-Carlo calculations of nucleon emission and energy deposition of spalla-tion neutron sources induced by intermediate energy protons were made. The cascade, evaporation, and fission reaction processes are considered in our calculations. The target materials 186W, 208Pb, 232Th, and 238U and incident proton energies 800, 1000, 1500, and 2000 MeV were chosen which are pencil beam on target axis. The number and spectra of neutrons and protons emitted from different regions of the target surface were calculated. The energy conservation is considered approximately, for which the bind energies are obtained according to the mass changing. The ionization energy induced by protons, nuclear recoil energy in cascade processes, and fission fragment energy in different regions inside the target are recorded. The calculated results show that the most of the outgoing neutrons are emitted from the front part of the target. Since the target is longer the most of the outgoing neutrons are emitted from 30~150 degrees against the z axis of the target. The calculated results also show that the most part of the deposited ionization energy, nuclear recoil energy, and fission fragment energy are distributed in the front part especially near the z axis of the target.