Real Potential in Alpha-Nucleus Scattering

Measurements of $\alpha$-nucleus elastic differential-cross-section data at 27 MeV from ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}$, ${}_{}{}^{65}{}_{}{}^{}\mathrm{Cu}$, ${}_{}{}^{90}{}_{}{}^{}\mathrm{Zr}$, and ${}_{}{}^{122}{}_{}{}^{}\mathrm{Sn}$, over the angular range 15 (×2.5) to 175° are reported. The data are analyzed using both a standard six-parameter optical model and a folding model. The latter uses an effective nucleon-$\alpha$ interaction obtained from a global analysis of free nucleon-$\alpha$ scattering data below 12 MeV incident nucleon energy which is folded with a nuclear matter distribution to obtain the real part of the $\alpha$-nucleus potential. The fits with the folding model are improved appreciably over those obtained using the standard optical model and are sensitive to the choice of matter parameters. The matter mean-square radii deduced are in good agreement with other estimates.