Elastic and inelastic neutron scattering cross sections for 10B, 11B, and 16O

Neutron scattering cross sections of high quality have been measured for 10B, 11B and 16O using the Triangle Universities Nuclear Laboratory neutron time-of-flight facility. These data are useful both for the CTR program and for studies of the isospin dependence of the nuclear force. The neutron data obtained are compared with high quality proton data for 10B to determine this dependence using the optical model, assuming that the isospin dependence may be expressed as a correction to the energy of the incident projectile. The energy correction is found to be 4.6 +- 1.4 MeV lowering of the incident energy for protons. The neutron data obtained for 11B were compared to the 10B neutron and proton data in an attempt to extract the symmetry terms (dependence on target isospin) but the data were insufficiently sensitive to this effect to yield good results. The spherical optical model alone was insufficient to predict the 16O data because of the many resonances in the energy region, so a model background was used for these data. Three resonances were added to an optical model background and tentative spin-parity and width assignments were made which gave a noticable improvement in the fits to the data. The 11B data (elastic and inelastic) were also fit using the coupled-channel optical model. A value for the coupling parameter was obtained from hyperfine structure results for the electric quadruple moment in the literature