Energy dependence of the 16O + 60Ni potential and the optical model dispersion relation

A systematic analysis of 16 O + 60 Ni elastic scattering data over a range of bombarding energies reveals strong variations of both the real and imaginary parts of the optical potential near the Coulomb barrier. The results are consistent with a dispersion relation interpretation of the effect which predicts a peak in the real surface potential close to the barrier.