Chaged Particle Multiplicities in Inelastic proton-proton Collisions with the ATLAS Detector.

The measurement of the charged particle multiplicities with the ATLAS detector in inelastic p − p collisions at center of mass energy of 900 GeV and 7 TeV are presented. The charged particle density, it’s dependence on pseudo-rapidity and transverse momentum and it’s correlation with the average transverse momentum is measured for events with at least two charged particles in the kinematic range |eta| < 2.5 and pT > 100 MeV. The measurements are compared to different Monte Carlo model predictions.