The large, oscillating backward angle cross sections that have been observed in recent ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ elastic data at $E\left({}_{}{}^{16}{}_{}{}^{}\mathrm{O}\right)=50\mathrm{} \mathrm{and} 55$ MeV are reproduced in an optical-model analysis using Woods-Saxon potentials.

NUCLEAR REACTIONS ${}_{}{}^{28}{}_{}{}^{}\mathrm{Si}$ (${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$), $E=50\mathrm{} \mathrm{and} 55$ MeV; calculated $\sigma \left(\theta \right)$; deduced optical-model parameters.

• Received 19 April 1978

DOI:https://doi.org/10.1103/PhysRevC.18.1944