Systematic studies of aging effects in RPCs for the CMS/LHC experiment

초록

An intensive aging study for the forward resistive plate chambers (RPCs) was performed by using a 200 mCi Cs-137 gamma-ray source. For the systematic aging study, four double-gap RPCs, 40 x 40 cm 2, were manufactured and tested for cosmic muons and the gamma rays irradiated from the source. The aging of the RPC gap is expected to be proportional to the integrated avalanche charge per unit area of the RPC. In this paper, a few diagnostic methods to observe aging phenomena are discussed, and the test result for a gamma irradiation of 150 days are presented. The integrated avalanche charge per unit area induced by the gamma rays in the RPC gap was 0.23 C/cm(2)/gap on average, which is equivalent to approximately 12 years of Compact Muon Solenoid (CMS) RPC operation.

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