A vertex trigger for the LHCb experiment

The LHCb experiment is designed to study CP violation in B-decays at the LHC machine at a luminosity of 2.10^32 cm-1 s-1 and a rate of 40 MHz. It is crucial to efficiently select the interactions containing B-mesons. The silicon detectors are of major importance to identify tracks from B-decays. The design of the LHCb detector and its trigger scheme is presented, with the emphasis on the algorithms and their use of the silicon detectors.