D.G. Koo

Performance of a large forward resistive plate chamber for the CMS/LHC under high radiation environment

Abstract We present the first beam test results of a real size prototype RPC for the endcap region of the CMS, one of large detectors at CERN LHC. The chamber was built with relatively low resistivity bakelite made in Korea and was operated successfully at the Gamma Irradiation Facility at CERN under the highest photon flux available, which corresponds to an effective cluster rate up to about 800 Hz / cm 2 . The cross-talk effects between strips and sectors have been studied extensively. The high voltage plateau, which satisfies the CMS requirements for efficiency and the number of strips fired per cluster, extends to at least 300 V . The time resolution has been measured to be better than 1.3 ns in this HV plateau region. These results demonstrate that the current design of the device can be used as a muon trigger detector for the CMS forward region.

Temperature and humidity dependence of bulk resistivity of bakelite for resistive plate chambers in CMS

Abstract This paper presents data obtained in a systematic study on the bulk resistivity of Korean bakelite as a function of temperature in the range 20–30°C and relative humidity in the range 35–65%. Strong dependence of resistivity on both temperature and humidity was observed. Measurements were carried out in the framework of R&D work on Resistive Plate Chambers (RPCs) which will be used in the CMS detector.

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

Abstract 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 SF 6 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.

Threshold dependence of strip clusters for the forward region resistive plate chamber of the CMS/LHC experiment

Strip clusters of muons and background hits induced by gamma rays and spurious pulses are analyzed for the Forward Region Resistive Plate Chamber of the CMS/LHC. In order to perform the analysis, a real size RE2/1 prototype RPC manufactured with the final baseline design of the Forward Region RPCs was tested at the Gamma Irradiation Facility of CERN. Strip cluster sizes for muons and strip cluster rates for gamma rays are sensitive to the threshold setting while the efficiency to muons is relatively insensitive.

Aspects of operational conditions of a double gap prototype RPC for the CMS/LHC experiment

This paper presents the results from cosmic ray tests performed in the framework of R&D effort on the forward Resistive Plate Chamber (RPC) for CMS. A double gapRPC of dimensions 50 � 50 cm 2 with 2 mm gas gaps was tested. We report data on the use of tetrafluorethane-based gas mixture, with additions of water vapour and SF6. Efficiency, time resolution and cross-talk behaviour of the detector were investigated. # 2001 Elsevier Science B.V. All rights reserved. PACS: 29.40.Cs