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

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.