Fragment Flow in Au<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mo>+</mml:mo></mml:math>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, ${}^{3}$He, ${}^{4}$He, 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.