Theoretical Approach and Computer Code System for Nuclear Data Evaluation of 20-1000 MeV Neutron Induced Reactions on Heavy Nuclei

Abstract

New approach for fission cross-section description in the energy region from 20 to 1000 MeV has been recently worked out. The developed code system is based on a detailed description of all stages of nucleon- induced reactions on heavy nuclei for E > 20 MeV including: description of entrance channel in the framework of coupled channel method with new optical model potentials for neutron- and proton-induced reactions; simulation of direct processes with the intranuclear cascade model; simulation of pre-equilibrium particle emission with hybrid Monte-Carlo model; description of fission/evaporation competitions on the base of detailed statistical model. The approach developed is adopted for evaluation of nuclear data for energies up to 1 GeV as follows: yields of evaporation residuals; yields of fission products; spectra of secondary gammas, protons and neutrons, including emission from fission fragments; total, elastic, fission and (n, xnyp) reaction cross-sections.