Gas gain stability of MSGCs operating at high rate

Micro Strip Gas Counters (MSGCs) with coated and uncoated borosilicate glass substrates have been investigated on their high rate capability and long-term gas gain stability. It is shown that the gain remains almost constant at count rates up to 105 mm−2 s−1 when a semiconductive layer of S8900 glass or polydiamond is applied under or over the strips. The application of such a coating also favours the gain stability at long-term operation. However, the maximum attainable gas gain for coated substrates is 4–10 times smaller than for bare borosilicate glass supports. For the latter substrate type, we observe less ageing when the strips are made of nickel instead of aluminium or copper.