Double-Differential Neutron Emission Cross-Section Measurements of ⁶Li and ⁷Li at Incident Neutron Energies of 8.17 and 10.27 MeV

Energy angular neutron emission double-differential cross sections (DDXs) of ⁶Li and ⁷Li were measured at incident neutron energies of 8.17 and 10.27 MeV, respectively, using normal and normal + abnormal fast neutron time-of-flight (TOF) spectrometers. The effects of breakup neutrons from a D(d,n) source and the influence of an aluminum container of Li samples, as well as ⁷Li in the ⁶Li sample and ⁶Li in the ⁷Li sample, on the secondary neutron spectra were eliminated. The data were derived by comparing the net TOF spectra with the calculated spectra using a realistic Monte Carlo simulation. The differential cross sections were determined by comparing the measured and simulated TOF spectra with respect to specific scattering fractions, i.e., with respect to the elastic lines and the resolved inelastic lines related to single levels or level groups, and normalized to n-p scattering. The angular distributions for the ⁶Li and ⁷Li elastic and inelastic neutron scattering were obtained also. The angle-integrated cross sections were derived for elastic scattering from ⁶Li and for the sum of elastic and 0.478-MeV state inelastic scattering from ⁷Li. Inelastic scattering cross sections were obtained for the 2.186-MeV state in ⁶Li and the 4.652-MeV state in ⁷Li. Meanwhile, based on the unified Hauser-Feshbach and exciton model, the calculated results of the DDXs for n + ^6,7Li were compared with measurements.