A highly efficient low-pressure UV-rich detector with optical avalanche recording

Abstract UV photons from a Cherenkov radiator are multiplied in a multistep avalanche chamber operating in a gated mode at low gas pressure (40 Torr). The gas mixture is C 2 H 6 -argon ( 80 20 ) and TMAE at 34°C. Visible light emitted from single photoelectron avalanches is detected by a CCD camera coupled to an image intensifier system. The detector was tested with 5 GeV c electrons, using a CH 4 radiator gas at 1 atm. Cherenkov rings essentially free of particle background and of secondary photon feedback were obtained in this mode of operation with a mean number n ≅ 11.5 ( N 0 ≅ 76 cm −1 ). We present this new method and discuss its performance.