Cross Sections and Isomer Ratios for theK41(α, n)Sc44m,44gReaction

The absolute cross sections for ${\mathrm{Sc}}^{44m}$ and ${\mathrm{Sc}}^{44g}$ have been determined at 1-MeV intervals from 8 to 19 MeV. The experimentally determined isomer-ratio function was compared with the theoretical predictions of a Huizenga-and-Vandenbosch-type calculation. A value of 1.7-1.8 for $\sigma$, the spin cutoff parameter, was found to give a good fit of the experimental isomer ratios below the ($\alpha , 2n$) threshold. Deviations of the calculated values from the experimental values above this threshold were interpreted to be the result of considerable spin fractionation.