The neutron energy spectra from the (p,n) reaction on ${}_{}{}^{90}{}_{}{}^{}$,91,92,94Zr, ${}_{}{}^{92}{}_{}{}^{}$,94,95,96,97,98,100Mo, and ${}_{}{}^{110}{}_{}{}^{}\mathrm{Pd}$ with 25 MeV protons and ${}_{}{}^{90}{}_{}{}^{}$,91,92,94Zr with 18 MeV protons are analyzed in terms of the preequilibrium exciton model introducing effective Q values, the pairing correlation, and the modified uniform spacing model in which the uniform spacing model is modified so as to have a wide spacing at the magic number. For all these targets, the calculated spectra using the above model for 25 MeV protons show good agreement with the experimental ones not only on the absolute cross sections in the neutron energy region of 12–18 MeV, but also on the observed spectra with pronounced structures in the neutron energy region higher than 18 MeV.

• Received 27 March 1987

DOI:https://doi.org/10.1103/PhysRevC.36.543