Density patterns and energy-angle distributions from a simple cascade scheme for fast 20Ne+238U collisions

A simple but fully three-dimensional cascade approach, appropriate for considering heavy-ion collisions at a few hundred MeV per projectile nucleon, is applied to 20Ne+238U. For impact parameters b/sub NeU/ of 0 and 5 fm the calculated results include densities rho(r,t) of nucleon masses during the collision and energy-angle distributions d2n/dEdΩ of scattered nucleon masses emerging from the collision. All of the present calculations use idealized nucleon-nucleon interactions implying cross sections sigma/sub N/N that are purely elastic, isotropic, and independent of the initial NN state. Some of these calculations also introduce excluded-volume effects, such as those associated with a classical hard core in the NN interaction. The calculated density rho(r,t) is quite sensitive to changes in the size of the excluded volume (we tried hard cores of radius 0, 0.5, and 0.9 fm). However, it is only in the case of zero excluded volume that rho(r,t) shows much sensitivity to changes in sigma/sub N/N (we tried sigma/sub N/N=15.4, 25.4, and 53.1 mb). The distribution d2n/dEdΩ is rather insensitive to the excluded-volume feature but does depend sensitively on sigma/sub N/N, on the impact parameter b/sub NeU/, and on the emitted-nucleon characteristics E and Ω. For one particular set of NN parameters: hard-core radius=0.9 fm, sigma/sub N/N=25.4 mb: our cascade calculation reduces to a case in which each nucleon is modeled precisely as a classical frictionless billiard ball (a ''hard sphere'') of diameter equal to the hard-core radius. For this case our cascade results would be especially suitable for comparison with analogous fluid-dynamic results: these latter to be computed using the known equation of state of a hard-sphere gas