Development of gas avalanche photodetector operating at cryogenic temperature

We are interested in developing a photodetector sensitive to liquid noble gas scintillation light which is able to operate in cryogenic environment down to liquid nitrogen temperature (77 K). It has to be a simple, cheap and compact device, with a photocathode surface comparable to that of photomultipliers, and it has to be able to produce fast signals for timing and triggering purposes. It could offer a cheap alternative to the photomultiplier use in large volume time projection chambers operating in liquid noble gas. died the possibility to couple a standard photocathode to a suitable electron multiplication system in gas. The results of the evaluation of the maximum gain attainable in gas employing pure argon and argon/methane mixture at low temperature are presented.