LHCb VELO Closing Control, Vertex Resolution and Luminosity Measurement

The LHCb Vertex Locator (VELO) surrounds the collision point at IP8 of the LHC ring and performs precise tracking and vertexing. This silicon micro-strip detector is built in two halves, which each move independently in the transverse plane so as to approach the collision region during data taking, but retract whilst the beams are injected and adjusted. The closing procedure of the VELO is detailed, along with an analysis of the primary vertex resolution and a description of the role of the VELO in the LHCb luminosity measurement.