Aging tests with GEM-MSGCs

The Inner Tracker of the HERA-B experiment at the Deutsches Elektronen-Synchrotron is a position-sensitive detector which has to cope with a particle flux up to 2×104 MIPs mm−2 s−1 and a radiation dose up to 1 Mrad/year (10 kGy/year). The system consists of Microstrip-Gas-Chambers using a Gas Electron Multiplier as preamplifier structure in the gas volume. During the R&D phase, long-term aging measurements with X-rays were performed to study which electrode material and counting gas do not lead to aging of the detector over long running periods.