Elastic Scattering of 39.6-MeV Protons by Even Isotopes of Ni and Zn

Differential cross sections and polarizations for 39.6-MeV protons elastically scattered from the isotopes ${}_{}{}^{58,60,62,64}{}_{}{}^{}\mathrm{Ni}$ and ${}_{}{}^{64,66,68}{}_{}{}^{}\mathrm{Zn}$ have been measured using the University of Minnesota linear accelerator. An atomic-beam-type polarized source was used for the polarization measurements. The data have been analyzed using both the standard optical model and a recent approach to the optical model developed by Greenlees, Pyle, and Tang, in which the real part of the central potential and the spin-orbit potential are obtained from the two-nucleon potential and the neutron, proton, and matter point-density distributions. Root-mean-square radii of the real central potentials are extracted from the data, but no systematic trend is evident for an isotopic sequence.