Münster 2011 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 22: Schwerionenkollisionen und QCD Phasen IV
HK 22.1: Group Report
Tuesday, March 22, 2011, 16:30–17:00, HS AP
Suppression of Charged Particle Production at Large Transverse Momentum in Central Pb−Pb Collisions at √sNN=2.76 TeV — •Jacek Otwinowski — GSI, Planckstr. 1, 64291 Darmstadt
Inclusive transverse momentum spectra of primary charged particles in Pb-Pb collisions at √sNN=2.76 TeV have been measured by the ALICE Collaboration at the LHC. The data are presented for central and peripheral collisions, corresponding to 0−5% and 70−80% of the hadronic Pb-Pb cross section. The measured charged particle spectra in |η|<0.8 and 0.3 < pT < 20 GeV/c are compared to the expectation in p-p collisions at the same √sNN, scaled by the number of underlying nucleon-nucleon collisions. The comparison is expressed in terms of the nuclear modification factor RAA. The result indicates only weak medium effects (RAA≃ 0.7) in peripheral collisions. In central collisions, RAA reaches a minimum of about 0.14 at pT = 6−7 GeV/c and increases significantly at larger pT. The measured suppression of high-pT particles is stronger than that observed at lower collision energies, indicating that a very dense medium is formed in central Pb-Pb collisions at the LHC.