Evaluation of Neutron Cross Sections of Carbon-12 for Energies up to 80MeV

Abstract

We have evaluated the cross sections of 12C for neutrons up to 80MeV, paying more attention to the intermediate energy range above 20MeV. For energies below 20MeV, the evaluated data of JENDL-3.2 were adopted with some modifications. In the energy range above 20MeV, total cross section and its covariance matrix were evaluated using a generalized least-squares method with available experimental data. The spherical optical model was used to evaluate reaction and elastic scattering cross sections. Inelastic scattering to the first 2+ state was calculated based on the DWBA. The optical potentials used in these calculations were obtained by means of the microscopic folding model based on the Jeukenne-Lejeune-Mahaux theory. Double-differential emission cross sections for neutron, proton, deuteron, triton, 3He, alpha-particle and other heavier products were calculated using the Monte-Carlo method by which three-body simultaneous breakup process and two-body sequential decay process were taken into account in n+12C multibody breakup reactions. Kerma factors calculated from the evaluated cross sections were also compared with measurements and other evaluations.