Time evolution of collision process and applicability of angular momentum correlation description for heavy-ion reactions

Abstract

We extend the angular momentum correlation description of peripheral heavy-ion collisions to study the time evolution picture of their interaction process in terms of the time power spectrum. This is done for both strongly asymmetric mass and (quasi)symmetric mass colliding nuclei. It is found that the pole spin correlation function implies a physically meaningful description of the collision, while the Gaussian, Lorentzian and exponential correlation functions yield an unphysical picture involving simultaneous rotation of the dinucleus in two opposite directions from the near-side and in two opposite directions from the far-side. The difference between the time evolution laws yields the difference between the angular distributions. As an illustration we analyse angular distributions calculated with different spin correlation functions. The pole spin correlation gives a good fit for the experimental angular distributions in the²⁸Si +⁶⁴Ni (E _lab=123 MeV) dissipative collision, while the corresponding predictions using Gaussian, Lorentzian and exponential spin correlations are in disagreement with the data.