ALICE (A Large Ion Collider Experiment) is the LHC (Large Hadron Collider) experiment
devoted to investigating the strongly interacting matter created in nucleus-nucleus collisions
at the LHC energies. The ALICE ITS, Inner Tracking System, consists of six cylindrical layers
of silicon detectors with three different technologies; in the outward direction: two layers of pixel
detectors, two layers each of drift, and strip detectors. The number of parameters to be determined
in the spatial alignment of the 2198 sensor modules of the ITS is about 13,000. The target alignment
precision is well below 10 mm in some cases (pixels). The sources of alignment information
include survey measurements, and the reconstructed tracks from cosmic rays and from proton–
proton collisions. The main track-based alignment method uses the Millepede global approach.
An iterative local method was developed and used as well. We present the results obtained for the
ITS alignment using about 105 charged tracks from cosmic rays that have