Münster 2011 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 30: Hauptvorträge III
HK 30.2: Hauptvortrag
Mittwoch, 23. März 2011, 12:15–12:45, HS1
Exploring compressed nuclear matter with HADES* — •Tetyana Galatyuk — Goethe-Universität, Frankfurt am Main, Germany — ExtreMe Matter Institute EMMI, Darmstadt, Germany
In the energy domain of Ekin=1−2 GeV per nucleon, HADES has measured rare and penetrating probes in C+C, Ar+KCl, p+p, d+p and p+Nb collisions. Our results demonstrate that electron pair emission in C+C collisions can essentially be explained as a superposition of independent N+N collisions. A comparison of the N+N reference spectrum with the e+e− invariant-mass distribution measured in Ar+KCl collisions, however, shows a pronounced excess radiation, which can be attributed to emission from the dense phase of the collision zone. Moreover, for the first time at SIS energies, a clear ω signal was observed. Also in p+p interactions at 3.5 GeV the inclusive production cross sections for π0, η, ρ and ω mesons are extracted for the first time. This result allows putting tight constraints on vector meson production in heavy-ion and elementary collisions at beam energies of a few GeV. Intriguing results where also obtained from the reconstruction of hadrons with open and hidden strangeness. While the measured hadron yields are well described assuming thermalization, the reconstructed double-strange baryon Ξ− appears about ten times more abundant than expected. This result will be discussed in the context of the exploration of the nuclear matter phase diagram in the region of finite density.
* Supported by GSI, BMBF/06FY9100I and Helmholtz Alliance HA216/EMMI