Enhancement of etching ability due to the addition of a trace of oxygen to the CF(sub 4)/iC(sub 4)H(sub 10) (80:20)

摘要

We studied wire chamber aging for so called fast gas of CF(sub 4)/iC(sub 4)H(sub 10) (80:20) under the high-radiation environment. It is clear that a trace of oxygen plays an important role. An addition of a trace of oxygen to this gas mixture is indispensable to steady operation of wire chambers in high-radiation environment. A lack of the oxygen leads to quick formation of deposits on the sense wire just after the irradiation. With a trace of oxygen, however, not only the gain stays constant for non-aged wires but also the gain recovers for aged wires. The recovery rate of the gas gain increases approximately proportionally to the oxygen concentration. It indicates that oxygen enhances the etching ability of the gas mixture. We guessed a mechanism based on the plasma chemistry of semiconductor product process. (author).