Flow and multifragmentation in nuclear collisions at intermediate-energies

Energy spectra of hydrogen and helium isotopes emitted in Au+Au collisions at 0.25, 0.40, 0.60, 0.80, 1.0, and 1.15A GeV have been measured. A systematic study of the shapes of the spectra reveals a significant non-thermal component consistent with collective radial flow. The strength of this component is evaluated as a function of bombarding energy. Comparisons of the flow signal to predictions of QMD and BUU models are made. Using reverse kinematics, breakup of gold nuclei has been studied in Au+C reactions at 1.0A GeV. The moments of the resulting charged fragment distribution provide evidence that nuclear matter possesses a critical point observable in finite nuclei. Values for the critical exponents gamma, beta, and tau have been determined. These values are close to those for liquid-gas systems and different from those for 3D percolation.