The Muon System of the GEM detector at the SSCL

The GEM Muon System is based on a large super conducting solenoidal magnet with no magnetic flux return. Three superlayers of muon tracking chambers are deployed outside the calorimeter to reconstruct the sagitta of the muon trajectory in the magnetic field. Iron flux concentrators are placed along the central axis of the magnet to create a radial component of the magnetic field, thereby increasing the momentum resolution at small angles. The muon system can be triggered, based on transverse momentum, and muon trajectories can be reconstructed from vertical stroke ηvertical stroke = 0 to 2.5. (orig.)