Commissioning and Plans for the LHCb Trigger

The LHCb detector has been designed to study with high precision rare $b$-hadron decays produced at the LHC. The LHCb trigger is of crucial importance in selecting the collisions of interest and is based on a two-level system. The first level, Level 0, is implemented in hardware and uses information from the calorimeter, muon and pile-up systems to select events containing particles with large transverse momentum while rejecting events with multiple interactions. The Level 0 trigger accepts events at a rate of 1 MHz with which the detector information is read out and fed into the High Level Trigger. This software trigger has an output rate of 2 kHz and takes the decisions based on fully reconstructed events. The trigger commissioning and its expected performance for some scenarios are discussed.