HIGH-RATE OPERATION AND LIFETIME STUDIES WITH MICRO-STRIP GAS-CHAMBERS

Micro-Strip Gas Chambers manufactured on supports with low resistivity, 10(9) to 10(12) Omega cm, can withstand without gain loss due to charging-up the very high rates expected in tracking detectors at CERN's Large Hadron Collider. Several technologies allowing to realize supports in this range of resistivity are described, namely electron-conducting glass and thin-layer conductive coatings. At very high radiation fluxes, the formation and deposit on electrodes of thin insulating layers cause premature deterioration of the detector. The ageing rate is found to be extremely sensitive to the purity and nature of the filling gas, and can be kept small only by a careful selection of the manufacturing materials. Experimental results on ageing are presented for several types of detectors.