Heavy ion collisons in three dimensions by the relaxation-time method

A quantum transport equation with two-body collisions included via a relaxation-time method, earlier applied to two-dimensional (slab) collisions, is now extended to three-dimensional calculations. A density matrix is constructed from self-consistent field wave functions and is time-evolved in cartesian coordinates. This dynamical model of the nucleus is applicable at all nonrelativistic energies. The semiclassical limit is discussed. Results are shown for 16O-16O collisions between 40 and 200 MeV/A lab energies. Hot spots and conditions for fragmentation are discussed. The threshold for breakup of the compound system formed in a head-on collision lies between 40 and 60 MeV/A lab energies. At these energies, the maximum density-averaged thermal excitation energy is 7 and 10 MeV/A (average temperatures 8 and 11 MeV), respectively, compared with a binding energy of 8 MeV/A. The system does not thermalize completely, and the distribution in momentum space is not quite isotropic when breaking up. (orig.)