ATLAS Inner Detector performance

The ATLAS Inner Detector consists of three subsystems using different tracking-detector technologies: silicon pixels, silicon strips and straw tubes. The combination gives ATLAS a robust, hermetic and efficient tracking system, able to reconstruct tracks at the highest foreseen LHC luminosities. The inner detector provides vertex and momentum measurements, electron identification and some K/π separation. The beam pipe design of ATLAS was changed recently, causing an increase of the radius of the first tracking layer. The consequences are discussed in this paper.