Jens Konopka | Searcharxiv

arXiv1996

Microscopic calculation of expanding nuclear matter

Quantum Molecular Dynamics (QMD) calculations are used to study the expansion phase in central collisions between heavy nuclei. The final state of such a reaction can be understood as the result of a entropy conserving expansion starting from a compact source. The properties of this hypothetic source, however, are in conflict with the assumptions used in fireball models. Moreover, this hypothetical source is not formed in the dynamical evolution of the system.

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arXiv1995

On the impossibility of temperature extraction from heavy ion induced particle spectra

Spectra of various particle species have been calculated with the Quantum Molecular Dynamics (QMD) model for very central collisions of Au+Au. They are compatible with the idea of a fully stopped thermal source which exhibits a transversal expansion besides the thermal distribution of an ideal gas. However, the microscopic analyses of the local flow velocities and temperatures indicate much lower temperatures at densities associated with the freeze-out. The results express the overall impossibility of a model-independent determination of nuclear temperatures from heavy ion spectral data, also at other energies e.g. CERN or for other species (i.e. pions, kaons, hyperons)!

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