INFLUENCE OF THE BULK RESISTIVITY OF GLASS WITH ELECTRONIC CONDUCTIVITY ON THE PERFORMANCE OF MICROSTRIP GAS CHAMBER

The optimization of parameters of microstrip gas chambers (MSGC) on gl ass substrata with electronic conductivity is presented. It was shown experimentally that a discharge voltage between anode and cathode stri ps did not change practically with a decrease of anode width from 13 t o 5 mu m, while at the same time the gain maximum increased from 1000 to 4800. The change of a conducting pattern thickness from 0.5 to 1.5 mu m improved the gain maximum by 30%. The measurements were made of t he rate capability of MSGC depending on the glass resistivity going in the range from 0.9 X 10(9) to 2 X 10(12) Omega cm. At higher resistiv ity the rate capability was limited by the modification of electric fi eld by current flowing along the resistive surface, and therefore the rate capability increased when decreasing the resistivity of the suppo rt. At the glass resistivity of about 10(11) Omega cm the rate capabil ity came to plateau, which was the result of the influence of space ch arge in gas on an electric field. The rate capability on the plateau d epended on a gas mixture and a chamber gain, and the value of 10(7) Hz /mm(2) was obtained for an Ar+20% CO2 gas mixture and a gain of 400 fo r 8 keV X-rays.