Elastic and inelastic scattering of 0.8 GeV protons by 89Y and 90Zr

The optical model and collective model DWBA approach to proton elastic and inelastic scattering was extended to momentum transfer of four inverse fermis. Elastic and inelastic proton scattering data at 0.8 GeV were taken on 89Y and 90Zr with the high-resolution spectrometer at LAMPF. These data were analyzed within the optical model and collective model DWBA, and the results, compared to similar analyses performed at projectile energies of 18 to 180 MeV. Approximations made in the theory to include relativistic effects were tested and found to be reasonable. The energy dependence of the projectile-nucleus empirical optical potential was clarified, and a detailed optical model analysis of the elastic scattering was performed. The elastic and inelastic cross sections were found to be insensitive to the inclusion of spin-orbit effects. The first observation of a giant multipole resonance excited by 0.8-GeV proton inelastic scattering was reported. The low-energy octupole resonance in 90Zr was found to have an isoscalar strength similar to that found by lower-energy alpha inelastic scattering investigations. It is concluded that the optical model and collective model DWBA provide a good description of the data to momentum transfers of four inverse fermis. As far as these reactions are concerned, the 0.8 GeV proton is quite similar to the lower-energy alpha particle. The increase of almost an order of magnitude in projectile energy does not, within this type of analysis, reveal any new nuclear structure information