Excitation functions and isomeric cross-section ratios for theZr90(n,p)90Ym,gandZr91(n,p)91Ym,gprocesses

Excitation functions were measured for the ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$(n,p${)}^{90}$ ${\mathrm{Y}}^{\mathit{m}+\mathit{g}}$ and ${}_{}{}^{91}{}_{}{}^{}\mathrm{Zr}$(n,p${)}^{91}$ ${\mathrm{Y}}^{\mathit{m}+\mathit{g}}$ reactions over the neutron energy range of 6.5 to 10.6 MeV. Use was made of the activation technique in combination with radiochemical separation and ‘‘low-level’’ ${\mathrm{\beta }}^{\mathrm{-}}$ counting. From the available experimental data isomeric cross-section ratios were determined. Statistical model calculations taking into account precompound effects were performed for the formation of both the isomeric and ground states of the product. The calculational results on the total (n,p) cross sections agree well with the experimental data. The measured and calculated cross sections for the formation of the isomeric states also agree up to an incident neutron energy of 10 MeV; at higher energies, however, the calculated values are appreciably higher. In the case of isomeric cross-section ratios good agreement was found between experiment and theory up to 10 MeV; at higher energies the calculated values are consistently higher.