Design features and test results of the CMS endcap muon chambers

Presented are the main design features and performance results of the Cathode Strip Chambers for the CMS Endcap Muon system. Although the strips are unusually wide (up to 16 mm) for the cathode-to-anode wire distance of 5 mm, the six-plane structure of these chambers yields a spatial resolution of about 80 mum, essentially uniform and independent of the strip width. In addition, the net spatial resolution of about one-tenth of the strip width at the hardware trigger level (300 ns) is obtained using a simple network of comparators. Time resolution achieved at the trigger level is similar to 4 ns (rms) that allows unambiguous tagging of bunch crossings which occur every 25 ns. Aging test results, including those obtained with a recirculating gas system, are discussed; only minor aging affects were observed. The aging studies were performed with large- scale chambers; 700 m of wire were irradiated for a dose up to 0.4 C /cm of the total accumulated charge.