Heavy Ions Studies in ATLAS

The ATLAS detector is designed primarily for proton-proton collisions but it will also participate in the Heavy Ion program of the Large Hadron Collider (LHC). The LHC will collide lead ions at the center of mass energy of $sqrt{s_{NN}}=5.5$ TeV (with a top energy of $sqrt{s_{NN}}=$2.75 TeV expected in 2010) and thus it will provide crucial information about hot and dense QCD matter formed in these collisions. We will take the advantage of unprecedented capabilities of ATLAS detector to measure global observables such as collective flow and particle multiplicities, jet quenching, modification of the high $p_{mathrm{T}}$ particle spectra and heavy-quarkonia suppression. Performance of the ATLAS detector to measure this phenomena is presented.