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Figure: CMS Global Trigger crate with prototype modules

The rightmost 4 VME slots (21-18) contain the GMT boards, slot 17 the GTFE readout board, slot 16 the TIM board, which broadcasts the clock and fast control signals to all boards. In slots 15-13 PSB boards receive trigger data from the Global Calorimeter Trigger. Slot 12 is free and in slot 11 the GTL Logic module calculates up to 128 Algorithms, which are combined to Final_OR signals on the FDL board in slot 10. In slot 9 a PSB board receives ‘Technical Trigger’ signals and sends them to the FDL board. The Final_OR signals go to the central Trigger Control board (TCS) in slot 7 and are transmitted via ‘L1AOUT’ modules in slot 5 and 6 to the TTC system of CMS.

It is the last stage of the Level-1 trigger system and decides for every LHC bunch crossing whether to reject or to accept a physics event for further evaluation by the High Level Trigger. The Global Trigger receives trigger objects from the Global Calorimeter Trigger and the Global Muon Trigger and applies in parallel up to 128 physics trigger requirements, so-called ‘Algorithms’. In addition, up to 64 so-called ‘Technical Trigger’ signals can be used to either accept or reject events. The Algorithm and Technical Trigger bits are then combined to a Final_OR signal to start the readout procedure of an event.

Select component on the left for detailed information.

For the new system upgrade, see uTCA system.

Documents and Links


Technical Documentation

Interface Documentation