Neutron Scattering and the Optical Model near A = 208 and Implications on the Inelastic Scattering Cross Section of Uranium-238

Differential elastic neutron scattering cross sections of ²⁰⁶Pb, ²⁰⁷Pb, ²⁰⁸Pb, and ²⁰⁹Bi are measured at incident neutron energy intervals of ∼25 keV from 0.6 to 1.0 MeV. Optical model parameters are obtained from the energy-averaged experimental results for each of the isotopes. The ²⁰⁹Bi model was selected for extrapolation to ²³⁸U by introducing a small (N - Z)/A dependence and the known deformation of ²³⁸U. Calculated results are descriptive of ²³⁸U total neutron cross sections from a few hundred keV to >15.0 MeV and of recently measured differential ²³⁸U elastic and inelastic neutron scattering distributions at energies of 3.0 MeV, including new experimental values explicitly obtained for these comparisons. The model and the measurements imply total ²³⁸U inelastic neutron scattering cross sections considerably larger than in common applied usage.