Evaluation of ²³²Th and ²³⁷Np fast neutron-induced fission cross sections by simultaneous evaluation approach

The neutron-induced fission cross sections for 232 Th and 237 Np were evaluated from 500 keV to 200 MeV and from 70 keV to 200 MeV, respectively. The experimental fission cross sections for 232 Th and 237 Np, as well as their ratios to the 235,238 U, and 239 Pu fission cross section in the EXFOR library, were reviewed and analyzed using the least-squares method. The newly published 232 Th/ 237 Np fission cross-section ratios, obtained from the time-of-flight measurements at the CERN n_TOF and CSNS Back-n facilities, have been added to the EXFOR database. The new evaluation shows that the 232 Th fission cross section is systematically lower than that provided by the JENDL-5 library.