Supported by the Michigan Space Grant Consortium
The Boltzmann-Ueling-Uhlenbeck (BUU) model is a semi-classical transport model that is used to study nuclear collisions. The colliding nuclei are represented as individual test particles (nucleons) which follow classical trajectories in a nuclear mean field potential, which contains information about the nuclear EoS. Classical billiard-ball collisions may occur if two nucleons pass close enough to one another. The Pauli-exclusion principle is employed and forbids any collision which would cause more than one nucleon to occupy the same state.
The model has previously been shown to obey the classical conservation laws of energy and momentum. However, it has also been shown that angular momentum is not necessarily conserved. Various algorithms were tested which would conserve the angular momentum of the system. The methods, which employ several different basic assumptions, affect observable quantities such as the collective flow. The extent of these effects are being currently examined.