The differential cross sections and analyzing powers for 200 MeV protons elastically scattered from ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ have been measured in the angular region 6-115°. The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ data were analyzed in terms of a local, complex, spindependent optical potential. The potentials were defined phenomenologically (simple or double Woods-Saxon forms) or derived from the impulse approximation in the Kerman-McManus-Thaler approach with and without a semiempirical correction for Pauli blocking. Acceptable fits to the data over the whole angular range were obtained only for a real central potential which exhibits a pronounced depression inside the nuclear surface, a feature also suggested by some theoretical models for medium-energy optical potentials.

NUCLEAR REACTIONS ${}_{}{}^{12,13}{}_{}{}^{}\mathrm{C}(\overrightarrow{p},p)$, $E_p=200\mathrm{}$ MeV; measured $\sigma \left(\theta \right)$ and $A\left(\theta \right)$; phenomenological optical-model analysis, deduced best-fit potentials for ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, comparison with impulse-approximation calculations.

• Received 22 July 1980

DOI:https://doi.org/10.1103/PhysRevC.23.616