Microscopic description of Coulomb and nuclear excitation of multiphonon states in 40 Ca + 40 Ca collisions

We calculate the inelastic scattering cross sections to populate one- and two-phonon states in heavy ion collisions with both Coulomb and nuclear excitations. Starting from a microscopic approach based on random-phase approximation, we go beyond it in order to treat anharmonicities and nonlinear terms in the exciting field. These anharmonicities and nonlinearities are shown to have important effects on the cross sections both in the low energy part of the spectrum and in the energy region of the double giant quadrupole resonance. By properly introducing an optical potential, the inelastic cross section is calculated semiclassically by integrating the excitation probability over all impact parameters. A satisfactory agreement with the experimental results is obtained.Ministerio de Ciencia y Tecnología PB98-111