The ($p$,$n$) cross sections were measured from about 2.5 to 5.8 MeV with about 100-keV target resolution for natural Pd, Ag, Cd, In, and Te and for ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$, ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$, ${}_{}{}^{103}{}_{}{}^{}\mathrm{Rh}$, ${}_{}{}^{105,106,108,110}{}_{}{}^{}\mathrm{Pd}$, ${}_{}{}^{107,109}{}_{}{}^{}\mathrm{Ag}$, ${}_{}{}^{111,112,113,114,116}{}_{}{}^{}\mathrm{Cd}$, and ${}_{}{}^{125,126,128,130}{}_{}{}^{}\mathrm{Te}$. Systematic uncertainties are about ±2% for ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$, ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$, and the natural targets and about ±4% for the other nuclei. The isotopic ${\sigma }_{p,n}$ are fitted by adjustment in the depth $W_D$ and diffuseness $a_D$ of the surface imaginary part of a proton optical model potential (OMP) that was chosen previously to describe precision ($p$,$n$) data for isotopes of Sn. The diffuseness $a_D$ is found to be nearly constant, about 0.4 fm, but the depth $W_D$ shows a large and systematic $A$ dependence. A study of the parameter space indicates that at least one OMP parameter must have a strong $A$ dependence and that $W_D$ is probably the only such single parameter that will suffice. The explanation of this anomaly is currently unclear.

NUCLEAR REACTIONS: Pd, Ag, Cd, In, Te, natural targets; and ${}_{}{}^{89}{}_{}{}^{}\mathrm{Y}$, ${}_{}{}^{93}{}_{}{}^{}\mathrm{Nb}$, ${}_{}{}^{103}{}_{}{}^{}\mathrm{Rh}$, ${}_{}{}^{105,106,108,110}{}_{}{}^{}\mathrm{Pd}$, ${}_{}{}^{107,109}{}_{}{}^{}\mathrm{Ag}$, ${}_{}{}^{111,112,113,114,116}{}_{}{}^{}\mathrm{Cd}$, ${}_{}{}^{125,126,128,130}{}_{}{}^{}\mathrm{Te}$, enriched isotopic targets, $E=2.5\mathrm{} \mathrm{to} 5.8$ MeV, target resolution ∼ 100 keV. Measured ${\sigma }_{p,n}$. Deduced optical model parameters.

• Received 14 May 1979

DOI:https://doi.org/10.1103/PhysRevC.20.2052