Angular distributions of the differential cross sections for the elastic scattering of 210 MeV ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$ from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ (3°–61°) and ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$ (3°–48°) have been measured. The cross sections exhibit diffractive oscillations at small angles and exponential falloff characteristic of nuclear rainbow scattering at large angles. The data beyond the rainbow angle make it possible to obtain unique optical model potentials for the ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$+nucleus interaction, thus eliminating the discrete ambiguities inherent in the lower-energy studies. By truncating the angular distributions, data up to the rainbow angle could be fitted with several discrete ambiguous potentials. Extrapolation of the unique potentials to lower energies provides an energy dependence of the real potential volume integral given by $J_R$/6A=$J_R^0$/6A-β ln$E_{\mathrm{lab}}$ with $J_R^0$/6A≊800±30 MeV ${\mathrm{fm}}^3$ and β≊100 MeV ${\mathrm{fm}}^3$, a result which is essentially consistent with proton elastic scattering.

• Received 19 August 1987

DOI:https://doi.org/10.1103/PhysRevC.37.132