Revision and status of the neutron nuclear data of 6Li and 7Li

The neutron nuclear data of 6Li and 7Li stored in JENDL-3PR1 have been partly revised for JENDL-3 by taking account of the experimental data measured after their evaluations. The revision was mainly based on the double-differential neutron emission cross section data measured in Japan. The 7Li(n,n't)α reaction cross section was slightly enhanced around 14 MeV on the basis of recently measured data using the tritium counting method. The spectra of the continuum secondary neutrons produced by the 6Li(n,n'd)α and 7Li(n,n't)α reactions were calculated by the three-body phase-space model with the Coulomb interaction between the two charged particles in the final states. In the evaluated files, they were described by about 30 pseudo levels with a 0.5 MeV interval. The secondary neutron spectra from the 6Li(n,2n) and 7Li(n,2n) reactions were given by the conventional evaporation mode. Two higher resonant states, which had not been contained in the JENDL-3PR1 evaluation, were included in the present evaluation for each nuclide. A coupled-channel chalculation was performed to interpolate and extrapolate the elastic and some inelastic scattering cross sections. The present revision was restricted to the neutron emitting reactions. In this report, method of the revision and status of the produced data files are described. (author)