Quasielastic nucleon-transfer cross sections have been mea- sured at energies ≊35% above the Coulomb barrier for ${}_{}{}^{58}{}_{}{}^{}$,64Ni ${+\mathrm{}}^{112}$,116,120,124Sn. The systematic trends were studied over the range of systems, which span a factor of 2 in neutron excess N-Z. The observed magnitude of the cross sections and their surface localization suggest that quasielastic processes play an important role in the average nucleus-nucleus potential, a quantity of considerable recent interest in near-barrier collisions of heavy systems.

• Received 2 December 1985

DOI:https://doi.org/10.1103/PhysRevLett.56.572