Shear viscosity to entropy density ratio in nuclear multifragmentation

Nuclear multifragmentation in intermediate-energy heavy-ion collisions has long been associated with liquidgas phase transition. We calculate the shear viscosity to entropy density ratio eta/s for an equilibrated system of nucleons and fragments produced in multifragmentation within an extended statistical multifragmentation model. The temperature dependence of eta/s exhibits behavior surprisingly similar to that of H2O. In the coexistence phase of fragments and light particles, the ratio eta/s reaches a minimum of depth comparable to that for water in the vicinity of the critical temperature for liquid-gas phase transition. The effects of freeze-out volume and surface symmetry energy on eta/s in multifragmentation are studied.