Indirect determination of the 230Th(n, f ) and 231Th(n, f ) cross sections for thorium-based nuclear energy systems
Résumé
The surrogate ratio method (SRM) was employed in the first experimental determination of the 231Th(n,f ) cross section, relative to the 235U(n,f ) cross section, over an equivalent neutron energy range of 360 keV to 10 MeV. The 230Th(n,f ) cross section was also deduced using the SRM, relative to the 234U(n,f ) cross section, over an equivalent neutron energy range of 220 keV to 25 MeV. The desired compound nuclei were populated using (3He,3He ) and (3He,α) reactions on targets of 232Th and 236U and relative fission decay probabilities were measured. The surrogate 230,231Th(n,f ) cross sections were compared to cross section evaluations and directly-measured experimental data, where available.