Predictions of elastic alpha particle scattering from theoretical nuclear densities.

Data for the diffraction region of the elastic scattering of 42--140 MeV ..cap alpha.. particles from /sup 42,44,48/Ca have been compared to calculations based on Hartree-Fock nuclear densities. The ..cap alpha..-particle optical potential was obtained from the densities using a double folding model where the effective interaction was adjusted to the scattering from /sup 40/Ca. This study is insensitive to the details of the reaction calculation because it is restricted to the diffraction region and is only for the purpose of comparing relative sizes. The predicted cross section is in good agreement with data indicating that the theoretical densities are correct in the vicinity of 10% of central density to approximately +- 0.1 fm. This uncertainty is dominated by the approximations in the reaction calculation.