An excitation function for elastic and inelastic scattering at ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=180\mathrm{}°\pm 2.0°$ has been measured for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$+${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$ in the energy range $14\lesssim E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\lesssim 25$ MeV. The data exhibit a strong enhancement at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}\simeq 19.5$ MeV with a width of ∼2 MeV. Elastic scattering angular distributions at $E_{{}_{}{}^{12}{}_{}{}^{}\mathrm{C}}\left(\mathrm{lab}\right)=30, 32, 35, \mathrm{and} 40$ MeV show oscillatory structure in the angle range $40°\lesssim {\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}\lesssim 110°$. It is not possible to describe the elastic scattering data with an energy independent optical model.

NUCLEAR REACTIONS ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{27}{}_{}{}^{}\mathrm{Al}$, measured $\sigma (\theta ,E)$ elastic and inelastic scattering, ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}-180\mathrm{}°\pm 2.0°$, $14<\mathrm{}{E}_{\mathrm{c}.\mathrm{m}.\mathrm{}}<25\mathrm{}$ MeV. Measured $\sigma \left(\theta \right)$ elastic, $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=20.8, 22.2, 24.2, \mathrm{and} 27.6$ MeV $14°<~{\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}<~110°$, deduced optical model parameters.

• Received 23 May 1979

DOI:https://doi.org/10.1103/PhysRevC.20.2143