ATLAS Experiment Silicon Inner Detector Alignment

The ATLAS experiment at CERN is preparing for Large Hadron Collider data at the end of 2007. ATLAS Inner Detector track reconstruction uses drift tube and silicon based subdetectors. ATLAS physics goals require positions of the silicon tracker modules to a precision better than 10 μm. Planned alignment of the silicon tracker combines a hardware system and track based algorithms. The silicon detector has 5832 modules with a corresponding 34992 degrees of freedom, requiring non-trivial alignment strategies to obtain the desired precision and novel software and hardware techniques. Silicon tracker alignment algorithms and their functionalities are described and initial results from a combined test beam setup and combined cosmic ray data taking are presented.