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Light charged fragments from the reactions Ar+ 'V at 35 MeV/nucleon and ' C+ ' C at 50MeV/nucleon have been measured with a 4m array. Transverse collective motion is observed for all fragment types and increases in strength for the heavier fragments. The transverse momentum is qualitatively similar for the di6'erent impact parameters selected by the midrapidity charge. The global transverse momentum analysis includes corrections for correlations due to momentum conservation. The results are compared to those at higher energies to investigate whether the same or a new reaction phenomenon produces the collective motion. We outline some implications for the extraction of thermodynamic information from the kinetic energy of emitted fragments.

A systematic study of energy spectra for light particles emitted at midrapidity from Au+Au collisions at E=0.25-1.15 A GeV reveals a significant non-thermal component consistent with a collective radial flow. This component is evaluated as a function of bombarding energy and event centrality. Comparisons to Quantum Molecular Dynamics (QMD) and Boltzmann-Uehling-Uhlenbeck (BUU) models are made for different equations of state.PACS numbers: 25.75.+r, 25.70.GhCollective motion plays an important role in the decay of excited nuclear matter and has been studied over a wide range of bombarding energies in heavy ion collisions