Total cross sections and isomeric cross-section ratios for (n, 2n) reactions in the energy region 12–18 MeV

Abstract

Abstract The activation method was used to measure excitation functions for total or isomeric (n, 2n) cross sections in the energy region 12–18 MeV for 93 Nb, 96 Ru, 104 Ru, 103 Rh, 102 Pd, 110 Pd, 128 Te, 130 Te, 142 Nd, 192 Os, 191 Ir and 198 Pt. Isomeric (n, 2n) cross-section ratios were measured for 110 Pd, 128 Te, 130 Te and 198 Pt in the whole energy region stated and were further obtained for 93 Nb and 103 Rh for two energies by combining experimental isomeric cross sections with special (n, 2n) cross-section systematics. The measured total (n, 2n) cross sections are discussed with respect to the dependence of this quantity on the neutron excess of the target nucleus. Later the results are compared with predictions from the statistical theory and special consideration is given to the competition between γ and neutron emission. From the isomeric cross-section ratios spin cut-off parameters σ(& h ;) were deduced according to the method of Vandenbosch and Huizenga. The same analysis was also applied to all isomeric (n, 2n) crosssection ratios available from the literature. The resulting properties of σ(&ħ;) are compared with the theoretical predictions.