ATLAS reach for Quarkonium production and polarization measurements

The ATLAS detector at CERN's LHC is preparing to take data from the first proton-proton collisions expected in the next few months. We report on the analysis of simulated data samples for production of heavy Quarkonium states J/ψ and ϒ, corresponding to an integrated luminosity of with center of mass energy of 14 TeV expected at the early ATLAS data. We review various aspects of prompt Quarkonium production at LHC: the accessible ranges in transverse momentum and pseudorapidity, spin alignment of vector states, separation of color octet and color singlet production mechanism and feasibility of observing radiative decays χc and χb decays. Strategies of various measurements are outlined and methods of separating promptly produced J/ψ and ϒ mesons from various backgrounds are discussed.