SYSTEMATIC STUDY OF NEUTRON-PRODUCTION CROSS-SECTIONS FOR HEAVY-IONS BY INTRANUCLEAR CASCADE-EVAPORATION CALCULATIONS

A systematic study was made on the equilibrium and nonequilibrium neutron production cross sections for heavy ions based on intranuclear cascade evaporation model calculations. The cross sections were estimated by the HIC code at 337 MeV/u for projectiles of alpha, C-12, Ne-20 and Ar-40 and targets of C-12, Fe-56 and Pb-207. Using the calculated cross sections, simple expressions for the production cross sections of both the equilibrium and nonequilibrium neutrons, that were previously proposed at a lower energy range through the analysis of experimental data, were extended to higher energies. The extended formulae well reproduced the systematic behaviors of the cross sections with varying the projectile and the target nuclei. The extended expression of the equilibrium neutron cross section is further modified so that a separate component of the cross section for each of the target-like and projectile-like fragments is described. The obtained expression is tested by HIC calculated data, showing a good reproducibility of the cross sections for both the fragments.