Shear Viscosity to Entropy Density Ratio in Au+Au Central Collisions

The shear viscosity (η) and entropy density (s) are studied for the central Au+Au collisions with the help of a microscopic transport model, namely the isospin-dependent quantum molecular dynamic model (IQMD). Employ the formula given in ref.1, η is calculated as a time dependent variable for different incident energies from 40MeV/u to 120MeV/u and the energy dependence of η/s of nuclear matter in the most compressed stage in collision process is displayed.