Mean energies of prompt fission neutrons in the neutron-induced fission of U-235 at primary energies in the range E-n < 20 MeV

摘要

The spectra of neutrons accompanying the induced fission of U-235 target nuclei are described theoretically. It is confirmed that a third neutron source must be introduced in order to reproduce the shape of experimental distributions at high energies of primary neutrons (previously, a third source was used in describing the spectra of neutrons emitted in Th-232 and U-238 fission). On the basis of experimental results and their analysis, the mean energy of fission neutrons is estimated as a function of the bombarding-neutron energy up to E-n = 20 MeV.