Hardware Implementation of ATLAS Level-1 Muon Trigger in the Barrel region

The level-1 muon trigger of ATLAS, in the barrel region, makes use of a dedicated detector RPC, Resistive Plate Chamber. The processing procedure is accomplished through a Low Pt and a High Pt trigger. To reduce the rate of accidental triggers, due to the background noise in the cavern, for both Low Pt and High Pt , the algorithm is performed in the η and φ projections. The Low Pt trigger uses the information generated in the two Barrel Middle RPC stations, each made of two RPC doublets, one in the η (bending) and one in the φ (non-bending) projection. The High Pt trigger uses the result of the Low Pt trigger and the information of the RPC Barrel Outer station. This station is made of two doublets, one per projection. The η and φ information is combined together to generate the Region-OfInterest, (ROI), that is the region in which a valid trigger was produced.