Soft QCD Measurements at 900 GeV and 7 TeV with ATLAS

We present results on charged hadron production in proton-proton collisions at the Large Hadron Collider and center of mass energies ps = 900 GeV and 7 TeV in the ATLAS Detector. Charged tracks are measured with high precision in the inner tracking system; track multiplicities, transverse momentum spectrum and the average track transverse momentum as a function of track multiplicity are compared to phenomenological models describing the soft QCD processes participating in the interaction. Although all models approximately describe the data, none show complete agreement, with the deviation between data and Monte Carlo becoming more significant at the the higher center of mass energy and for higher track transverse momentum. These data have been used in the determination of a new optimised model which provides a much improved description of the data.