Nuclear Science and Engineering / Volume 163 / Number 3 / November 2009 / Pages 272-284
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.