Dresden 2000 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 29: Physik mit schweren Ionen V / Experiment und Theorie
HK 29.5: Vortrag
Donnerstag, 23. März 2000, 18:00–18:15, B 114
Collective flow from SIS to SPS — •E. Zabrodin1,2, Amand Faessler1, C. Fuchs1, and L. Bravina1,2 — 1Institut für Theoretische Physik, Universität Tübingen, Auf der Morgenstelle 14, 72076 Tübingen — 2Institute for Nuclear Physics, Moscow State University, 119899 Moscow, Russia
The microscopic quantum molecular dynamics (QMD) model and quark-gluon string model (QGSM) are used to study the collective flow of nucleons and pions in heavy ion collisions at energies from SIS to SPS. We focus mainly on the impact parameter dependence of directed and elliptic flow for light and heavy colliding systems. A significant reduction of the directed flow in midrapidity range, which can lead to the development of the antiflow, is found at energies of SPS and higher [1,2]. The effect is caused by the absorption of early emitted particles by massive spectators (shadowing effect). Indeed, particles emitted with small rapidities in “normal" direction can be easily absorbed by the spectators, while particles emitted in the opposite direction remain unaffected. This mimics the softening of the equation of state (EOS) and can be misinterpreted as indication on the formation of the quark-gluon plasma (QGP). However, in the absorption scenario the antiflow is stronger for the system of light colliding nuclei than for the heavy ones, while in the case of the plasma creation the effect should be opposite.
[1] L.V. Bravina, E.E. Zabrodin, Amand Faessler, C. Fuchs, Phys. Lett. B in press.
[2] E.E. Zabrodin, Amand Faessler, C. Fuchs, L.V. Bravina, Phys. Rev. C submitted.