Performance of the ATLAS vertex detector

The ATLAS inner detector consists of three layers of silicon pixels, four double layers of silicon microstrips and a transition radiation tracker (straw tubes). The good performance of the track and vertex reconstruction algorithms is a direct consequence of the small radius (4.3, 10.1 and 13.2 cm), fine pitch (50*300 mu m) and low occupancy (<3*10/sup -4/ at design luminosity) of the pixel detectors. The full (GEANT3) detector simulation is used to evaluate the performance of the detector and of the reconstruction algorithms. Results are presented on track and vertex reconstruction efficiencies and resolutions, and on the separation between b-jets and jets produced by light quarks. (8 refs).