LATTICE-GAS MODEL FOR FRAGMENTATION - FROM ARGON ON SCANDIUM TO GOLD ON GOLD

The recent fragmentation data for central collisions of gold on gold a re even qualitatively different from those for central collisions of a rgon on scandium. The latter can be fitted with a lattice gas model ca lculation. Effort is made to understand why the model fails for gold o n gold. The calculation suggests that the large Coulomb interaction wh ich is operative for the larger system is responsible for this discrep ancy. This is demonstrated by mapping the lattice gas model to a molec ular dynamics calculation for disassemhly. This mapping is quite faith ful for argon on scandium but deviates strongly for gold on gold. The molecular dynamics calculation for disassembly reproduces the characte ristics of the fragmentation data for both gold on gold and argon on s candium.