Isospin dependence of collective flow in heavy-ion collisions at intermediate energies

Abstract

Within the framework of an isospin-dependent Boltzmann-Uehling-Uhlenbeck (BUU) model using initial proton and neutron densities calculated from the nonlinear relativistic mean-field (RMF) theory, we compare the strength of transverse collective flow in reactions ${}^{48}Ca{+}^{58}Fe$ and ${}^{48}Cr{+}^{58}Ni$, which have the same mass number but different neutron/proton ratios. The neutron-rich system (${}^{48}Ca{+}^{58}Fe$) is found to show significantly stronger negative deflection and consequently has a higher balance energy, especially in peripheral collisions. NOTE ADDED IN PROOF: The new phenomenon predicted in this work has just been confirmed by an experiment done by G.D. Westfall et al. using the NSCL/MSU radioactive beam facility and a spartan soccer. A paper by R. Pak et al. is submitted to PRL to report the experimental result.

Comments: Latex file, 9 pages, 4 figures availabe upon request; Phys. Rev. Lett. (June 3, 1996) in press