Preequilibrium (p,p') measurements and calculations for 90Zr and neighboring nuclei for incident energies up to 200 MeV

Double differential cross sections have been measured for inclusive (p,p') reactions on targets of 89Y, 90Zr, and the even-mass Mo isotopes from A=92 to 98 at incident proton energies of 120, 160, and 200 MeV. Comparisons are made with calculations based on the statistical multistep direct theory of Feshbach, Kerman, and Koonin. In general it is found that the theory gives a good description of the angular distributions. Possible explanations for the deviation of the predicted cross sections from experiment at very low and very high excitation energies of the residual nucleus are given