Darmstadt 2008 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 13: Physik mit schweren Ionen
HK 13.6: Vortrag
Montag, 10. März 2008, 18:00–18:15, 2E
Centrality dependence of proton and antiproton yields in Pb+Pb collisions at √sNN=17.3 GeV — Hans Beck1, Julian Book1, Christoph Blume1, Peter Dinkelaker1, Volker Friese2, Marek Gazdzicki1, Claudia Höhne2, Dmytro Kresan2, Benjamin Lungwitz1, Michael Mitrovski1, Rainer Renfordt1, Tim Schuster1, Reinhard Stock1, Claudia Strabel1, Herbert Ströbele1,2, •Milica Utvic1, and Alexander Wetzler1 for the NA49 collaboration — 1Fachbereich Physik der Universität Frankfurt — 2Gesellschaft für Schwerionenforschung (GSI), Darmstadt
The centrality dependence of proton and antiproton spectra in high energy nuclear collisions is used to study the evolution of baryon stopping and transverse flow with the volume of interacting matter. The (anti −) proton yields in Pb+Pb minimum bias collisions at √sNN=17.3 GeV were measured by the NA49 Collaboration. They were identified in the c.m. rapidity interval -0.4 < y < 1.0 (corresponding to the laboratory momentum range 5-40 GeV/c) via their specific energy loss in the TPC detector gas. The resulting raw yields were corrected for geometrical acceptance, reconstruction efficiency and feeddown from weak decays. Rapidity distributions, transverse mass spectra and inverse slope parameters were studied as a function of collision centrality and compared to published data. It is found that the ratio of antiprotons to protons at midrapidity increases approximately by a factor of 2 from peripheral to the most central collisons.