The LHCb VErtex LOcator

The dedicated CP violation experiment at the Large Hadron Collider (LHC), LHCb, will be equipped with a novel silicon detector (Vertex Locator—VELO). The VELO will provide precise measurements of tracks from displaced b-vertices and will allow to trigger on them. The entire detector will be housed in a mobile secondary vacuum system, and after the injection and stabilisation of the beams each fill, the silicon detectors will move inwards and approach to within 7 mm of the beams. In order to fulfill the trigger requirements, the VELO must combine in an unprecedented way the use of high resolution silicon detectors and large CPU farms. The extreme, non-uniform radiation environment puts additional constraints on the sensor design. The design of the VELO is described, along with the R&D of the silicon sensors and its production status.