Measurements of cross sections for high energy neutron induced reactions on Co and Bi

There are few experimental data for neutron cross-section libraries in (n,xn) reactions for various materials at energies above 20 MeV. For neutron energies above 20 MeV, these set of (n,xn) reactions are important for neutron fluence monitoring and spectra unfolding for future generation IV nuclear reactors. There were attempts to measure the cross-sections on natural cobalt and bismuth at incident neutron energies of about 90 MeV and 140 MeV. These measurements were made using the quasi-monoenergetic neutron facility at iThemba LABS, South Africa. In addition, at The Svedberg Laboratory facility in Sweden, similar experiments were performed on natural Yttrium. The measured cross-sections were compared with some of the few available data for neutron-induced reactions at high energies. Data collected from these two facilities, required corrections to be made for the contribution of the low energy tail (continuum) in the incident neutron spectrum. Preliminary results from iThemba LABS showed large discrepancy which we suspect was due to instability of the proton beam during the irradiations. Follow-up experiments are planned to accurately determine the uncertainty contributions, with additional data at other neutron energies.