Actinide Neutron-Induced Fission up to 200 MeV

Abstract

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.

Keywords:

• nucleon-induced fission
• actinides
• intermediate energies