Trigger logic of the ATLAS First Level Muon Trigger

We present the design of the first level muon trigger in the central toroid of the ATLAS experiment at the Large Hadron Collider (LHC). The trigger is based on fast, finely segmented gaseous detector, Resistive Plate Chambers (RPC), to unambigously identify the interac- tion bunch crossing and to provide a sharp threshold over a large interval of transverse momentum. We describe the logic scheme of the trigger and the performance of the local trigger logic we have realized.