Alice Alignment, Tracking and Physics Performance Results

The ALICE detector was designed to track and identify particles in a wide transverse momentum range, from more than 100 GeV/c down to ~100 MeV/c. The innermost barrel-like detector, the Inner Tracking System (ITS), is dedicated to precise tracking and to primary and secondary vertices reconstruction. In this proceeding we present the ITS performance for tracking, primary vertex reconstruction and particle identification capability. The current understanding of the detector response is the result of an extensive phase of commissioning started with 2008 cosmic-ray run and finalized with data from pp collisions: the alignment status of the three ITS sub-systems (Silicon Pixel Detectors, Silicon Drift Detectors, Silicon Strip Detectors) and the study of the detector material budget via the reconstruction of gamma conversion in the material are presented. Precise tracking is required to reconstruct and separate the primary vertex of interaction from secondary vertices from hyperons and heavy-flavour meson decays: some examples of the achieved results are shown.