ATLAS Silicon Pixel and Strip Detector: Commissioning with Cosmic Data

The ATLAS experiment at the CERN Large Hadron Collider (LHC) has started taking data last autumn with the inauguration of the LHC. Determination of vertex position and charged particle tracks is performed in the Inner Detector which consists of pixel and microstrip Silicon sensors and transition radiation tubes. In this talk construction and commissioning of pixel and microstrip detectors will be presented. The Pixel Detector is the innermost detector of the ATLAS experiment with approx. 80 million readout channels. After connection of cooling and services and verification of their operation the ATLAS Pixel Detector is now in the final stage of its commissioning phase. Prior to the first beams expected in Autumn 2009, a full characterization of the detector is performed. The SemiConductor Tracker (SCT) is made up from silicon micro-strip detectors processed in the planar p-in-n technology.Sensors are assembled into 4000 modules with 6 million readout channels.The completed SCT detector was operated for many months under realistic conditions. Calibration data has been taken and analysed to determine the noise performance of the system. In addition, extensive commissioning with cosmic ray events has been performed both with and without magnetic field. The cosmic muon data has been used to align the detector, to check the timing of the front-end electronics as well as to measure the hit efficiency of modules. Both subdetectors wer e run both in standalone and in a combined mode (also with other ATLAS subsystems). One recent cosmic ray event with hits in the entire Inner Detector is shown in Figure 1. The current status of the Pixel and SCT Detectors will be reviewed, including results from the data-taking periods in autumn 2008, and from the detector alignment. We will report on the commissioning of the detector, including overviews on services, connectivity and observed problems. The commissioning and running experience will then be used to extract valuable lessons for future silicon detector projects.