A ring-imaging Cherenkov counter with a low-pressure two-step UV-detector

Abstract The application of low-pressure two-step gas detectors to the ring-imaging Cherenkov (RICH) technique is demonstrated. A RICH prototype with a UV-photon detector of 20×20 cm 2 , filled with 53 mbar of C 2 H 6 + TMAE at 30°C, was exposed to 3 GeV c electrons. Photoelectrons were localized with a FADC system with a spatial resolution of 2 mm rms. The ring reconstruction technique is presented. The advantages of using this method in high background experiments, such as in relativistic heavy ion collisions, are discussed.