Neutron-induced fission cross sections of U, Np and Pu target nuclides are analyzed in fission/evaporation approximation up to 200 MeV excitation energy. Damping of collective modes contribution to the level density at excitation energies higher than ~20 MeV for saddle and equilibrium deformations is shown to be essential. Effective estimates of intrinsic level densities are obtained. Actinide first-chance fission cross sections of 238U(n, f) and 238U(p, f) reactions are found to be much different. Differences of measured proton- and neutron-induced fission cross sections of 238U are attributed to the influence of the isovector term of the nucleon-nucleus optical potential.
- Intermediate energies
- Nucleon-induced fission
ASJC Scopus subject areas
- Nuclear and High Energy Physics
- Nuclear Energy and Engineering