Classical simulations of heavy-ion collisions

Abstract

We have carried out simulations of central collisions between two heavy ions by the classical molecular dynamics method. The ions used in these simulations are bound spheres of charged argon atoms, and the chosen mass numbers for the collisions are 108 on 108, 65 on 65, and 16 on 200. A few hundred collisions are studied for five energies chosen to span fusion-fission, multifragmentation, and total vaporization reactions. We have also studied the disassembly of hot liquid drops containing 216 and 130 particles. By comparing collisions and disassembly we establish the formation of equilibrated hot matter in the collisions. The density of the hot matter formed appears to be ∼80% of the equilibrium density, and its temperature depends upon the beam energy. All the beam energy thermalizes in equal mass collisions; however, a large fraction of it is lost in pre-equilibrium emission in the asymmetric 16 on 200 collisions. Mass yields and energy spectra of the particles emitted in collisions and disassemblies are reported, and the role of the liquid-gas phase transition is discussed. The yield of small clusters having $A_c$<30 particles is approximately given by the & power law. The ${\tau }_{\mathrm{eff}}$ depends on the energy of the collision, and has a minimum value of ∼1.7 as observed in nuclear fragmentation reactions.