Charge accumulation at the interface between two dielectrics and gas gain variation of microstrip gas chambers

Gas gain variations as functions of time have been observed with microstrip gas chambers. They are attributed here to charging of the substrate surface between electrodes. Based upon the concept of quasi-electrostatic fields a rule of charge accumulation is derived. Gas conductance is studied in order to apply the rule to a surface exposed to gas. A relation between substrate resistivity and the rate of detected particles for stable gain operation is then obtained by means of this rule. A comparison with experimental results yields good agreement.