Links:
General Description:
The task of the Global Muon Trigger (GMT) is to combine the results of the CSC, DT, and RPC muon systems by finding the four best muons of every bunch crossing and transmitting them to the Global Trigger (GT). The GMT improves the overall efficiency and rate capability exploiting the complementarity of the subsystems. It also helps to reduce the number of spurious muons ("ghosts").
In addition to finding the four best muons the GMT appends two bits set by the Calorimeter Regional Trigger, a MIP bit and an isolation bit, also called quiet bit, to each of the muon data words. The MIP bit is set if the calorimeter energy is consistent with the passage of a minimum ionizing particle, the isolation or quiet bit is set if a certain energy threshold in the trigger towers surrounding the muon is not exceeded. Both bits are used in the GT to suppress background and to improve selectivity.
The GMT must not introduce any dead time. Every bunch crossing is processed successively by pipelined logic in order to maintain high efficiency, crucial for physics channels with low cross sections.
The Global Trigger Crate with the Global Muon Trigger section on the left:
The Global Muon Trigger card block diagram:
