The trigger system of the muon spectrometer of the ALICE experiment at the LHC

In the framework of the ALICE physics program, the goal of the muon spectrometer is the study of quarkonia and open heavy flavors production via the muonic decay channel in a wide range of transverse momentum and in the pseudo-rapidity range -4.0< @h<-2.5. The trigger system of the muon spectrometer consists of four planes of Resistive Plate Chamber (RPC) detectors, 21 thousand front-end channels and fast-decision electronics. It is designed to select (muon) tracks via a rough transverse momentum d etermination, in a large background environment, and to provide a fast trigger signal. The results of the commissioning phase will be reported.