C12-C12elastic scattering at 1.016, 1.449, and 2.4 GeV and theNNamplitude

Abstract

Working within the framework of the Coulomb modified Glauber model, we analyze the elastic angular distribution and reaction cross section for the $^{12}\mathrm{C}$-$^{12}\mathrm{C}$ system at 1.016, 1.449, and 2.4 GeV. The elastic $S$ matrix is evaluated using the effective profile function approach, and a correlation expansion for the Glauber amplitude is obtained. We emphasize the parametrization of the basic (input) $\mathit{NN}$ amplitude, which may be used for a wide range of angles. Retaining the first two terms of the correlation expansion and using the realistic densities for the colliding nuclei, we find that (i) the consideration of higher momentum transfer components, and hence the nondiffractive behavior, of the $\mathit{NN}$ amplitude provides a more satisfactory account of the data than does the conventional (one-term) Gaussian parametrization for the $\mathit{NN}$ amplitude, (ii) the in-medium effects seem to reduce the (free) $\mathit{NN}$ total cross section and influence the other parameters of the $\mathit{NN}$ amplitude as well, (iii) the phase of the $\mathit{NN}$ amplitude does not help in improving the theoretical situation, and (iv) the c.m. correlations play an important role at the energies considered. We also discuss the suitability of the effective profile function approach in the present context.