Micro strip gas chambers with gas electron multipliers and their application in the CMS experiment

Micro Strip Gas Chambers (MSGCs) have become a very popular type of gaseous detector throughout the last decade. However, its good spatial resolution and high rate capability was overshadowed by instabilities when operated in environments with a high particle flux. Since a major part of the tracking system of the upcoming Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) was planned to be built based on this technology, considerable efforts have been taken to solve those difficulties. This thesis looks at one possible approach to get rid of high rate instabilities: the application of a Gaseous Electron Multiplier (GEM) as a second amplification stage for an MSGC. The design goal was to build a robust detector with the capability of operating safely in the harsh LHC environment with expected particle fluxes up to 104Hz/mm2 while maintaining the full MSGC performance in terms of spatial resolution and detection efficiency. Such detectors have been successfully built. Stable operation with particle fluxes up to 3x104Hz/mm2 could be shown. Full detection efficiency of 99% has been reached at a signal to noise ratio of 18. A spatial resolution of better than 40μm has been achieved. A full scale detector in the CMS baseline design for the forward tracker has been realised and successfully tested in LHC-like conditions.