Track-Based Alignment of the Inner Detector of ATLAS

ATLAS is a multipurpose experiment at the LHC. The tracking system of ATLAS, embedded in a 2T solenoidal field, is composed of different technologies: silicon planar sensors (pixel and microstrips) and drift-tubes and amounts to almost 700,000 degrees of freedom. We will present the results of the alignment of the ATLAS tracker using data recorded during 2010 and 2011 using the LHC proton-proton collision runs at 7 TeV. Validation of the alignment was performed by measuring the alignment observables as well as many other physics observables, notably resonance invariant masses in a wide mass range (K0s, J/Psi and Z0). The E/p distributions for electrons from Z->e+e- and W->enu were extensively used. The systematic errors due to the alignment that may affect physics results are under study. The results of the alignment with real data reveal that the attained precision of the alignment constants is approximately 5 microns.