Maximum freeze-out baryon density in nuclear collisions

Using simple parametrizations of the thermodynamic freeze-out parameters extracted from the data over a wide beam-energy range, we reexpress the hadronic freeze-out line in terms of the underlying dynamic quantities, the net baryon density ρB and the energy density {ε}, which are subject to local conservation laws. This analysis reveals that ρB exhibits a maximum as the collision energy is decreased. This maximum freeze-out density has μ=400--500 MeV, which is above the critical value, and it is reached for a fixed-target bombarding energy of 20--30 GeV/nucleon.