C12+12C elastic scattering analysis aboveE/A=6 MeV using deep real potentials

We present phenomenological and folding optical-model descriptions of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ ${+}^{12}$C elastic scattering between 6 and 120 MeV/nucleon. The potentials have a deep real part, a weakly absorbing imaginary part, and are energy dependent. The folding-model real potential is calculated from the energy- and density-dependent effective interaction DDM3Y. It requires renormalizations of about 1.1 below 10 MeV/nucleon, and close to unity above. The phenomenological real potential is about 300 MeV at the center for the lower energies, slowly reducing to 120 MeV for the highest energies. The discrete ambiguities for the real part found in the analysis at energies below 10 MeV/nucleon are resolved by demanding consistency with the higher energy results. The volume integrals for the folding-model and phenomenological potentials agree and display a smooth and slow energy dependence that is consistent with simple dispersion-relation predictions. The values for the total reaction cross sections show the transparency effect expected from microscopic calculations. A possible extension of this description towards lower energies is discussed.