LIQUID AND SOLID PHOTOCATHODES AND THEIR APPLICATIONS FOR FAST GASEOUS PARTICLE DETECTORS

Two types of liquid photocathodes were investigated: semi-transparent and reflective. Experiments have led to the conclusion that, in the case of semitransparent photocathodes, the photoemission increases strongly at certain thicknesses, when the 'electron temperature' of the photoelectrons obtained in the applied electric field E is higher than the conduction-band energy V(O) of the liquid. In the case of reflective photocathodes, a thin intermediate layer of vapor between the liquid and the gaseous phases contributes also to the creation of photoelectrons, deteriorating the timing properties of the photocathode. The best timing properties (approximately 1 ns) and the highest quantum efficiency were achieved with a reflective photocathode made from a substrate with a small working function, covered by an adsorbed layer of photosensitive vapors.