TREATMENT OF HEAVY ION COLLISIONS AT INTERMEDIATE ENERGIES

Microscopic calculations of intermediate energy heavy ion collision are performed employing the Boltzmann Uehling Uhlenbeck (BUU) formalism. We see that at beam energies around the Fermi energy the system does not equilibrize although the spectra show an exponential form. Preequilibrium particles are preferably emitted to the opposite site of the impact parameter as suggested by the Fermi jet model. We discuss furthermore the linear momentum transfer, the nuclear mean free path and the formation of a third cluster at midrapidity which reflects nicely the importance of both - two body collisions and mean field - at these beam energies