An aging study by semi-conductive microstrip gas chambers

The aging behavior of wire chambers have been of great interest for many years. Recently, a new generation of proportional chambers have been built including the microstrip gas chamber (MSGC) microgap chamber (MGC) and gaseous electron multiplier (GEM). Aging studies of these detectors are of particular interest to the Large Hadron Collider (LHC) community because the baseline design of the CMS experiment includes MSGCs as part of the tracking system. We have performed a series of aging tests of large pitch, 1 mm MSGC’s constructed on semiconductive glass substrates operated in argon and dimethyl ether (DME). The quencher, DME is believed to chemically react with some materials of organic origin commonly used in gas systems, shortening the lifetime and deteriorating the performance of the detectors. Great care was taken to minimize unwanted chemical reactions and all materials suspected to react with DME were removed from areas where the DME gas flows. With these precautions, we have demonstrated that the MSGC can tolerate about 150 mC/cm of accumulated charge without significant degradation of the chamber performance. This corresponds to about 15 yr of operation at the LHC.