Beam test results of a large forward Resistive Plate Chamber for the CMS/LHC

The first real size Resistive Plate Chamber (RPC) prototype of ME2/1 for the forward region of the Compact Muon Solenoid (CMS) detector was constructed at Korea Detector Laboratory (KODEL). The parallel resistive electrodes of the double gap RPC were made of bakelite whose resistivity was 5×109 Ω cm. The prototype was tested at the Gamma Irradiation Facility (GIF) of CERN in an environment of the background intensity ranging up to 1 kHz/cm2/gap. We report that the full efficiency of 98% has been achieved with time resolution of about 1 ns. These results demonstrate that such a double gap RPC is suitable for the muon trigger in the future experiments.