Fragment flow in Au +Au collisions

Exclusive measurements have been made of Au +Au reactions with beam energies ranging from 0.25 A to 1.15 A GeV. We present measurements of directed collective flow averaged over all light fragments with masses up to alphas, as well as separate measurements for protons, deuterons, tritons, 3He, 4He, and Li. The results show a strong increase of the directed flow with fragment mass at all energies measured. Experimental results are compared with a quantum molecular dynamics model. We find that neither the soft nor the hard equation of state can describe the data over the entire range of beam energies.