EUROPEAN LABORATORY FOR PARTICLE PHYSICS CERN-PPE/97-60 6 March 1997 OPERATION OF MICRO-STRIP GAS CHAMBERS MANUFACTURED ON GLASS COATED WITH HIGH RESISTIVITY DIAMOND-LIKE LAYERS

We describe recent observations and measurements realized with microstrip gas chambers (MSGCs) manufactured on boro-silicate glass coated with a thin layer of diamond-like carbon (DLC) having a surface resistivity around 4.1016Ω/❒. The role of the back-plane electrode configuration and potential in the detector performance has been studied. Even for this very high resistivity of the coatings, MSGCs operate differently from those manufactured on bare borosilicate glass; the charge gain increases with the radiation flux for counting rates above 10 Hz/mm, reaching a value 60% higher for 10 Hz/mm. This behavior does not depend on the presence and potential of the back plane electrode; however, both maximum gain and rate capability are influenced by the drift field. From this study, compared with measurements realized previously with other detectors, we deduce that for stable high rate operation of MSGCs the resistivity of the coating should not exceed ~10 Ω/❒. Submitted to Nuclear Instruments and Methods in Physics Research a On leave of absence from Institute of Experimental Physics, Warsaw University, Poland