A post-evaporation quantum efficiency measurement system for large area CsI photocathodes for the Hall A RICH detector
INFN - Roma1, gr. Sanita'
A proximity focusing freon/CsI RICH detector has been built for kaon physics at Jefferson Lab, Hall A. The Cherenkov photons are detected by a UV-photosensitive CsI film
which has been obtained by vacuum evaporation. A dedicated evaporation facility for large area photocathodes has been built for this task. A measuring system has been built to allow the evaluation of the absolute quantum efficiency just after the evaporation. We will describe the evaporation facility and the quantum efficiency-measuring device. First results of the measurements performed and their comparison with in-beam data will be presented.