The influence of transport variables on isospin transport ratios

The influence of transport quantities on isospin equilibration in peripheral $^{112}$Sn+$^{112}$Sn, $^{112}$Sn+$^{124}$Sn, $^{124}$Sn+$^{112}$Sn, and $^{124}$Sn+$^{124}$Sn collisions is studied in the Boltzmann-Uehling-Uhlenbeck model. The isospin transport ratio constructed from the asymmetry of the projectile residue has been shown to contain information about the density dependence of the symmetry energy. However, the ratio also depends on the momentum dependence of the mean field, in-medium isospin nucleon-nucleon cross-sections, and the stiffness of the symmetry part of the equation of state (EOS). Our simulations will try to untangle the various effects and their influence on the extraction of the symmetry energy terms in the EOS. First results from the simulations and comparisons to other transport model calculations will be presented. This work is supported by the National Science Foundation under Grant PHY-0606007.