Strong Energy Dependence of the Optical Potential for S 32 + Ni 5 8 , 6 4 near the Coulomb Barrier

The elastic scattering of $^{32}\mathrm{S}$+$^{58,64}\mathrm{Ni}$ was measured at sulfur beam energies of 82, 88, 91, 93, 98, 102.5, 108, and 150 MeV. Evidence is found for a marked energy dependence of the optical potential at the strong-absorption radii around the Coulomb barrier, in good agreement with parallel information extracted from the fusion cross sections for the same systems.