The excitation function at 90° in the c.m. system, just above the Coulomb barrier, and an angular distribution at 13-MeV c.m. energy, were analyzed with a conventional complex potential of Woods-Saxon shape. The excellent fit obtained led to almost the same parameters that were used to describe ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$-${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ scattering data at higher energies by Siemssen et al. A real ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$-${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ interaction with a repulsive core does not fit the excitation function at c.m. energies from 10-14 MeV, contrary to the conclusion of Brueckner et al. When absorption is added, the Coulomb potential masks the nuclear interior, and thus the elastic scattering data cannot be used as sensitive evidence for the existence of a repulsive core. The conclusion of Brueckner et al. seems to be affected by incorrect phase shifts.

• Received 1 November 1968

DOI:https://doi.org/10.1103/PhysRev.180.1049