Advances in ultraviolet and visible range photo cathodes for gaseous detectors

Photosensitive gaseous detectors provide an attractive solution for photon localization over very large areas and under high illumination flux. They offer single photon sensitivity and possibility of operation under very intense magnetic fields normally encountered in high energy physics experiments. A large variety of photosensitive gaseous detectors has been developed over the last two decades and is successfully employed in numerous experiments in high energy and nuclear physics, plasma diagnostics and medical imaging. Here we discuss the recent progress made in UV-photo cathodes capable of operation under gas multiplication and visible photo cathodes providing, for the first time, the possibility of operating gaseous detectors in the visible range. (author)