Msgc Development for Hera-b

The Inner Tracker System of the HERA-B experiment at DESY is build by groups 1 at the Universities of Heidelberg, Siegen and Zürich. The system consists of 184 Microstrip-Gas-Chambers (MSGC) with a total number of 147 456 electronic channels. The detectors have to cope with particle fluxes up to 25 kHz mm−2 and to tolerate radiation doses of 1 Mrad per year. During the development of these chambers it was found that conventional MSGC, operated in intense hadronic fluxes, are rapidly destroyed due to the phenomenon of induced discharges. The introduction of a Gas Electron Multiplier (GEM) as preamplification structure offers the possibility to build robust and reliable detectors allowing for ample gain reserve in the hostile environment of HERA-B.