Cosmic tests and performance of the ATLAS SemiConductor Tracker Barrels

ATLAS is a multi-purpose particle detector for the LHC and will detect proton collisions with center of mass energy of 14 TeV. Part of the central inner detector, the SemiConductor Tracker (SCT) barrel, is now fully integrated with the Transition Radiation Tracker (TRT) barrel. The SCT module performance has been measured after module production, after macro-assembly of modules onto barrels, after arrival at CERN and again partially after integration with the TRT. The module noise average per channel has been stable and is 4.5 × 10 - 5 , well below the design specification of 5 × 10 - 4 . There is no evidence for common mode noise problems and 99.8 % of the 3.2 million channels of the SCT barrels are functional. The cosmics running of the SCT and TRT was the first large scale test of the physics mode of the SCT online software framework. A large sector, 468 SCT modules, has been timed in and read out during the cosmic tests. Tracks have been reconstructed through the SCT and the TRT sectors. Present residuals from tracks (without alignment) are better than the specified building tolerances of the SCT.