LHCb VELO tracking resolutions

The LHCb detector at the Large Hadron Collider (LHC) at CERN is designed to make precision measurements of mesons and baryons containing b and c quarks. Many analyses performed using data from LHCb examine properties of particles and anti-particles as a function of proper decay time. Precise measurements of production and decay vertices are thus essential. The Vertex Locator (VELO) subdetector of LHCb performs this task. The excellent performance of the VELO with respect to the resolutions it achieves on single hits, impact parameters, and primary vertex positions is presented, with particular attention paid to measurement of impact parameters.

► Tracking resolutions achieved by the VELO at LHCb are presented.
► The best single hit resolution is 4μm.
► Impact parameter (IP) resolutions are <35μm for pT>1GeV.
► Primary vertex (PV) resolutions in x and y   are <13μm when using >25>25 tracks.
► There is a discrepancy between data and simulation of ∼20%∼20% in IP and PV resolution.