PROGRESS IN CHERENKOV RING IMAGING Part 1: Detection and localization of photons with the multistep proportional chamber

The multistep proportional chamber, operated with a photosensitive gas filling, makes it possible to obtain stable multiplication factors in excess of 106 and can be used for the detection of single photoelectrons released in the gas. The efficiency and localization properties of the device in the detection of vacuum ultraviolet photons are discussed here, in view of its use for particle identification exploiting the Cherenkov ring-imaging method.