Study on the operational conditions of a double-gap resistive plate chamber for the CMS

We present the results from cosmic ray tests on the forward Resistive Plate Chamber (RPC) for the CMS. Double-gap prototype RPC were built and tested in the Korea Detector Laboratory (KODEL). We found that addition of SF6 and water vapor to the tetrafluorethane-based gas mixture was required for the long-term stable operation of RPC. Efficiency, time resolution as well as cross-talk behavior of the detector were investigated. In addition, we present the temperature and humidity dependence of bulk resistivity of Korean bakelite in detail.