Isomer Ratios from (α, xn) Reactions on Silver

摘要: Excitation functions have been measured for the ${\mathrm{Ag}}^{107}(\ensuremath{\alpha}, n){\mathrm{In}}^{110,110m}$ and ${\mathrm{Ag}}^{109}(\ensuremath{\alpha}, 3n){\mathrm{In}}^{110,110m}$ reactions with isotopically separated targets. The excitation high-spin metastable state peak in both at higher bombarding energies than low-spin ground state. In case of n)$ reaction, cross section formation ${\mathrm{In}}^{110}$ peaks a helium-ion energy about 17 MeV that ${\mathrm{In}}^{110m}$ 19.5 MeV. isomer ratio, $\frac{{\ensuremath{\sigma}}_{m}}{({\ensuremath{\sigma}}_{m}+{\ensuremath{\sigma}}_{g})}$, determined reaction varies from 0.13 10.8 to 0.81 22.0 3n)$ this ratio 0.68 27.6 0.87 38.7 experimental sections are based on half-lives 70.2\ifmmode\pm\else\textpm\fi{}1.4 min 5.2\ifmmode\pm\else\textpm\fi{}0.2 h ${\mathrm{In}}^{110m}$, respectively. ratios were calculated theoretically above effects various parameters calculations examined. below 18 agree within uncertainties results either Fermi-gas model rigid moment inertia (${\ensuremath{\sigma}}^{2}=34.7t$) or superconductor model. A predicts only 20% reduction such small change could not be definitely established data. marked increase is observed near onset ($\ensuremath{\alpha}, 2n$) reaction. This probably due fractionation intermediate spin distribution slightly exceeding threshold second effect suggested also by where competition sizeable. These indicate values $\ensuremath{\sigma}$ deduced technique error competing large.