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HK: Fachverband Physik der Hadronen und Kerne
HK 44: Schwerionenkollisionen und QCD Phasen
HK 44.7: Talk
Thursday, March 22, 2012, 18:15–18:30, P 5
Centrality dependent J/ψ production in Pb-Pb collisions at √sNN=2.76 TeV with ALICE — •Ionut-Cristian Arsene — Research Division and ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum fürSchwerionenforschung, Darmstadt, Germany
The hot and dense nuclear matter formed in ultra-relativistic nuclear collisions is one of the testing grounds for the theory of strong interactions. The J/ψ meson is a very interesting probe for understanding the properties of the medium created by such collisions. It was predicted that at high temperature the J/ψ state is melting leading to the suppression of this particle with respect to pp. However it was also predicted that high production rates of charm quarks at RHIC and LHC energies will make possible (re)combination of charmonium states thus leading to J/ψ enhancement. In the ALICE detector, J/ψ is measured at mid-rapidity, |y|<0.9, and forward-rapidity, 2.5<y<4.0, down to zero transverse momentum. The reconstruction is done via the di-electron channel at mid-rapidity and the di-muon channel at forward-rapidity. The electron identification is done using linear energy loss in gaseous detectors, Time Projection Chamber (TPC), Transition Radiation Detector(TRD), and the time of flight method, Time Of Flight(TOF) detector. The muon identification is done using the MUON spectrometer where the tracking devices are placed behind thick hadronic absorbers. We will present J/ψ production densities as a function of rapidity and collision centrality. Furthermore, using the cross-sections measured by ALICE in pp collisions at the same energy we will show and discuss the nuclear modification factor.