HETC96/MORSE calculations of activations in KEK beam stop and room by 500-MeV protons and comparisons with experiments

The 1996 version of HETC has a pre-equilibrium reaction model to bridge the gap between the existing intranuclear-cascade and evaporation models. This code was used to calculate proton-induced activations, to calculate neutron fluxes for neutron energies above 19.6 MeV, and to write the neutron source for lower energies to be transported further by MORSE. For MORSE, the HILO cross section library was used for neutron transport for all detectors. Additionally for the 197Au(n,γ) detector, the BUGLE96 library was used to study the effects of the low-lying 57Fe inelastic levels and the resonance self-shielding in iron. Neutron fluxes were obtained from the track-length estimator for detectors inside the beam stop and from the boundary-crossing estimator for detectors attached to the surfaces of the concrete walls. Activation cross sections given in JAERI-Data/Code are combined with the calculated neutron fluxes to get the saturated activities induced by neutrons. C/E values are too low (0.5) for Fe(n,x)54Mn, close to unity for Cu(n,x)58Co, and too high (6.0) for 197Au(n,γ)198Au. It is difficult to interpret the disagreements because most of the activation cross sections are also calculated and their uncertainties are not known. However, the calculated results are in good agreement with those calculated by others using different codes. Calculated results for four of the ten activations reported here have not been done previously, and among the four, 197Au(n,γ) is the most bothersome because its cross section is the most well known while the calculated activations for most detector locations are in largest disagreement with experiments. (author)