Sc44Isomeric Yield Ratios

Abstract

${}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$ isomeric yield ratios have been measured for the three reactions ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}(\gamma ,n){}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ti}(\gamma ,np){}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$, and ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}\mathrm{}(n,2n)\mathrm{}{}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$. Scandium oxide and titanium samples were irradiated with 48-MeV bremsstrahlung to obtain the photo-induced reactions. For the ($n,2n$) reaction 14-MeV neutrons were used. The yields of ${}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$ in the ground and isomeric states were determined by the measurement of the residual gamma activity. A statistical-model calculation of the type used by Huizenga and Vandenbosch was performed in order to obtain the value of the spin cutoff parameter $\sigma$ consistent with the experimental data. The following isomer yield ratios [(yield of ground state)/(total yield)] were obtained: for ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}(\gamma ,n){}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$, 0.86±0.02; for ${}_{}{}^{46}{}_{}{}^{}\mathrm{Ti}(\gamma ,np){}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$, >0.98; for ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}\mathrm{}(n,2n)\mathrm{}{}_{}{}^{44}{}_{}{}^{}\mathrm{Sc}$, 0.58±0.02. The experimental results agree with the calculated ratios for values of the spin cutoff parameter $\sigma$ between 2 and 3.