ATLAS: inner detector technical design report; 7, level-2 trigger

The Level-1 trigger system makes use of information from a subset of detectors, the calorimeter and muon systems, at a reduced granularity. The role of the Level-2 trigger is to utilise full granularity information from the majority of detectors, but in most cases in limited regions identified by Level-1. This includes information from the Inner Detector. A search for tracks in the TRT and precision layers can be used to complement the information from the calorimeter and muon systems. This, together with a refinement of the information from the detectors used at Level-1, allows a reduction of -100 in the rate at which events are passed on to the Event Filter.