Preequilibrium (p,p’) spectra for nuclei around neutron number 50

Energy spectra of protons emitted from (p,p’) scattering were measured for ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$, ${}_{}{}^{92}{}_{}{}^{}$,94,96,98,100Mo, ${}_{}{}^{106}{}_{}{}^{}\mathrm{Pd}$, and Ag at an incident energy of 18 MeV. It was shown that there were no appreciable shell and odd-even effects on the preequilibrium proton spectra corresponding to excitations higher than 4 MeV of the residual nucleus. The experimental results were interpreted on the basis of the state densities generated from two sets of single particle levels using the recursion method by Williams et al.; one is based on the spherical Nilsson model, and the other on the modified uniform spacing model in which a shell gap is introduced into the uniform spacing model. The measured angle-integrated proton spectra were compared with those calculated on the basis of the exciton model and the Hauser-Feshbach model in which the isospin selection rule was taken into account. Good agreement between the experimental and calculated spectra was obtained for all targets in the continuum region in the outgoing proton energy region of 3–14 MeV.