INTERMEDIATE-ENERGY HEAVY-ION COLLISIONS WITH G-MATRIX POTENTIALS AND CROSS-SECTIONS

We present the first quantum molecular dynamics calculations of heavy-ion collisions in which the effective nucleon-nucleon potential and the nucleon-nucleon cross sections in a medium are consistently calculated in the Brueckner theory from the basic Reid soft-core potential. The strong momentum dependence of the Brueckner G-matrix yields a quite different time evolution of heavy-ion collisions as compared with that obtained via Skyrme potentials adjusted to nuclear matter properties and the optical potential. In the calculation of Nb + Nb collisions at 400 MeV/u, we find that the transverse momentum transfer is much larger than that obtained with the hard Skyrme potential, although the compressibility (K = 182 MeV) is even lower than that of the soft Skyrme potential (K = 200 MeV). This raises questions about the possibility of uniquely determining the parameters of the nuclear equation of state from heavy-ion collisions at intermediate energies. The momentum transfer has two physically quite different reasons: the strong momentum dependence of the G-matrix potential causes a strong transverse momentum very early in the time evolution of the reaction, i.e. before the system is compressed. Additional transverse momentum is transferred in the compression phase, similar to observations for Skyrme-like potentials. The momentum transfer in the second process is about that of the soft Skyrme potential, which is not unexpected because the compressibilities are similar and in both calculations about the same density is reached.