Measurements of neutron spectra and fluxes at spallation-neutron sources and their application to radiation effects research

The neutron spectra, fluxes and flux distributions produced by nuclear spallation resulting from 478 MeV proton bombardment of Ta and depleted uranium targets surrounded by a thick Pb neutron reflector were measured. The configuration was chosen to simulate a radiation effects facility at a spallation -- neutron source. The method of the multiple foil activation with spectrum unfolding by the STAYSL computer code was used to measure the neutron spectra. The experimental results are compared in detail with the results of computer calculations on the same configuration of targets and reflector. The neutron production and transport codes HETC and VIM were employed in these calculations. The neutron spectra, and characteristic parameters for studies of radiation effects, are compared with those of fission-neutron sources. Based on the above measurements, the predicted performance and capabilities of the Radiation Effects Facility at the Intense Pulses Neutron Source at Argonne National Laboratory are discussed.16 refs.--AA