Soft QCD in ATLAS: Minimum bias and diffraction studies

We present measurements on charged particle production in proton-proton collisions at centre-of-mass energies of root(s)= 0.9, 2.36 and 7 TeV recorded with the ATLAS detector at the Large Hadron Collider. Events were collected using a single-arm minimum bias trigger, charged tracks are measured with high precision in the inner tracking system. Minimum bias analysis uses data samples at all three energies, while diffractive events are studied using a sample of events at roo(s})= 7 TeV. To study diffractive interactions, the events that have hits on exactly one side of the ATLAS detector were selected. The charged particle multiplicity, pseudorapidity and transverse momentum spectra are analiyzed and compared to the predictions by various Monte Carlo models.