a b s t r a c t Operation of Gas Electron Multiplier (GEM) in pure xenon was studied in a double-phase chamber under well-controlled conditions, in terms of temperature, pressure and gas purity. The maximum gain of % 150 was achieved in gas phase at À108 C. Stable operation, during several hours, was observed.

No abstract

Operation of Gas Electron Multiplier (GEM) in ultra-pure xenon was studied for gas at 25 1C, cold but not saturated gas at À90 1C and saturated xenon vapour at À102 1C. The most stable operation was observed at À90 1C for which the maximum visible gain of 150 was obtained from a single GEM. The maximum gain of E40 was achieved for saturated xenon vapour at À102 1C and of E25 for twophase configuration at the same temperature. Continuous operation of a GEM in two-phase mode for periods of several hours was routinely achieved.