Gines Martinez-Garcia (Laboratoire de Physique Subatomique et des Technologies Associees)
ALICE detector has excellent performances to study quarkonium production in heavy-ion collisions at the LHC collider . In this new energy regime, charmonium could reveal a privileged probe to study the properties of the high-density strongly interacting system formed in the early stages of high-energy heavy-ion collisions . Bottomonium resonances will be abundantly produced, providing new constrains on theoretical models of quarkonium dissociation in QCD matter . Additionally, ALICE will study quarkonium production in proton-proton collisions in which high particle multiplicity events could lead to the formation of high energy density matter as in heavy ions collisions . In ALICE , quarkonium is measured down to pT = 0 via their mu+mu− decay channels in the ALICE muon spectrometer and via their e+e- in the ALICE central barrel. After a short description of the apparatus, the transverse momentum and rapidity distributions of inclusive J/Psi production cross section in proton-proton collisions at LHC energies will be presented. We will discuss the dependence on charged particle multiplicity of J/Psi yield in proton-proton collisions at sqrt(s) = 7 TeV. The number of reconstructed tracklets (η<1.6) in the silicon pixel detector is exploited to measure the charged particle density at mid- rapidity. Finally, the analysis of the inclusive J/Psi production in Pb-Pb collisions at a centre of mass energy of sqrt(sNN) = 2.76 TeV will be described. Preliminary results on the nuclear modification factor (RAA) and the central to peripheral nuclear modification factor (RCP) will be shown.  ALICE collaboration, PPR II, J. Phys. G32, 1295 (2006)  P. Braun-Munzinger and J. Stachel, Phys. Lett. B490, 196 (2000); R.L. Thews, M. Schroedter and J. Rafelski, Phys. Rev. C63, 054905 (2001); A. Andronic et al., Phys. Lett. B571, 36 (2003); L. Grandchamp, R. Rapp and G.E. Brown, Phys. Rev. Lett., 92, 212301 (2004).  K. Werner et al. arXiv:1010.0400v1 (2011); K. Werner et al., Phys. Rev. Lett. 106, 122004 (2011).  ALICE collaboration, J. Instrum. 3, S08002 (2008).