Brueckner theory and the heavy ion optical potential

Abstract

Starting from the Brueckner theory a method for the calculation of the real and imaginary parts of the heavy ion potential is developed. The heavy ion potential is calculated solving the Bethe-Goldstone equation for two colliding nuclear matters with different densities. The transition from infinite nuclear matter to the collision of finite nuclei is obtained by using improvements of the local density approximation or of the double folding method. The Feshbach definition of the optical potential is used to justify this procedure. It should be reliable if the two-particle two-hole excitation energy is small compared to the kinetic energy of the heavy ion projectile and if the hole line expansion of the Brueckner theory can be used. Real and imaginary parts of the heavy ion optical potential calculated in this way depend very strongly on the center-of-mass energy. They agree favourably with phenomenological fits of such potentials. The imaginary part shows consistently a slightly too small radius. This is explained by the contributions of the surface vibrational states which can not be taken into account in an approach based on nuclear matter. Calculated cross sections for different heavy ions and different bombarding energies show a surprisingly good agreement with the experimental data.