The various phenomenological potential form factors which describe the elastic scattering of $\alpha$ particles from a given target nucleus are similar at large radii. It is shown that reasonably accurate limits can be placed on both the magnitude and falloff rate of the potential in this surface region close to the maximum of the Coulomb barrier. This surface-region potential is found to be well reproduced by a simple folding of the nuclear-matter distribution with a two-body potential which fits free nucleon-$\alpha$ scattering.

• Received 21 December 1970

DOI:https://doi.org/10.1103/PhysRevC.3.2229