Operation of a single-GEM in noble gases at high pressures

We report the performance of a single-Gas Electron Multiplier (GEM) operating in pure Ar, Xe, and in Ar-50lmbar Xe mixtures, in the range of 1-7lbar. The maximum gain and voltage that can be applied to the GEM are investigated as a function of filling pressure and compared to the results obtained with triple-GEM and MHSP (Micro Hole and Strip Plate) multipliers. The maximum gain achieved at llbar Xe is about 103, presenting a fast decrease with pressure to values around 300, 50 and 10 at 2, 3 and 5lbar, respectively. Gains around 100 were achieved in Ar up to 4lbar, decreasing to values of few tens at 6lbar. On the other hand, gains around 500 can be achieved in Ar-50lmbar Xe mixtures up to 5lbar, presenting a fast reduction at higher pressures due to the limitations on the maximum gain imposed by the GEM discharge limit. Nevertheless, gains above 100 can be obtained for pressures between 6 and 7lbar, indicating a good potential for neutron detection. (c) 2007 Elsevier B.V. All rights reserved.