Proton scattering fromC12between 120 and 200 MeV and the optical potential

Abstract

Cross sections and analyzing powers are presented for $^{12}\mathrm{C}(\stackrel{\ensuremath{\rightarrow}}{p}, p)^{12}\mathrm{C}$ elastic scattering at 122 and 160 MeV. The data cover a large angular range (up to ${\ensuremath{\theta}}_{\mathrm{lab}}=154\ifmmode^\circ\else\textdegree\fi{}$) and extend to lower energies an earlier, similar measurement at 200 MeV. The complete data set is analyzed in the framework of the optical model. Besides the standard Woods-Saxon potential, nonstandard radial shapes for the central and the spin-orbit potentials are investigated. Although the number of free parameters for the nonstandard potential is substantially reduced from the standard potential, it provides an improved fit to the data and a description of $^{12}\mathrm{C}(p, p)^{12}\mathrm{C}$ scattering with a simple monotonic energy dependence in the region 100-200 MeV. The characteristic features of the nonstandard potential are reproduced by microscopic theories.