Muon Endcaps (ME)

The muon endcaps [27] cover a polar range of about $0.67 < \vert\cos\theta\vert < 0.985$ either side of the detector. Each consists of eight quadrant chambers, which are 6 m $\times$ 6 m in size, and four patch chambers, 3 m $\times$ 2.5 m in size. The chambers are filled with 75% argon and 25% isobutane and consist of two layers of limited streamer tubes. All the streamer tubes are aligned perpendicular to the beam axis. One layer has the wires in the tubes aligned vertically and the other horizontally. The spatial resolution is $\sim$ 2 mm.