Köln 2004 – wissenschaftliches Programm
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HK: Physik der Hadronen und Kerne
HK 14: Poster Session: Heavy Ions
HK 14.12: Poster
Dienstag, 9. März 2004, 13:30–15:30, Foyer
System size dependence of strangeness production at 158 A·GeV‡ — •I. Kraus1, C. Alt2, C. Blume2, P. Buncic2, P. Dinkelaker2, D. Flierl2, V. Friese1,3, M. Gazdzicki2, M. Kliemant2, S. Kniege2, B. Lungwitz2, M. Meurer2, M. Mitrovski2, S. Radomski1, R. Renfordt2, A. Richard2, A. Sandoval1, R. Stock2, and H. Ströbele2 — 1Gesellschaft für Schwerionenforschung (GSI), Darmstadt — 2Institut für Kernphysik, Universität Frankfurt — 3Fachbereich Physik der Universität, Marburg
In heavy ion collisions at the top CERN-SPS energy the transition to a deconfined state of strongly interacting matter is expected. With the large acceptance hadron spectrometer NA49 data on Pb+Pb, as well as on elementary p+p collisions have been collected. In order to study the transition between these extreme cases and to gain deeper insight into the transition from a hadronic to a partonic state, medium size systems (C+C and Si+Si) have been analysed in addition. Spectra and yields of π-, K- and φ- mesons as well as Λ- and Λ-hyperons were measured.
The yields of strange particles per pion show a rapid rise with increasing system size, followed by a saturation above approx. 60 participants. This can be explained in the framework of statistical models by the transition from canonical to grand canonical ensembles. The rapidity spectra of the hyperons show increasing stopping. Furthermore, the transverse mass spectra flatten with increasing system size. This indicates the incidence of collective effects, which leads to the qualitative difference between heavy ion collisons and the superposition of p+p interactions.
‡Supported by BMBF and GSI