Advances in vacuum ultraviolet detection with multistep gaseous detectors and application to cerenkov ring imaging

The multistep avalanche chambers permits an efficient detection of VUV photons. In a two-step proportional mode charges higher than 1 pC are obtained from single electrons. By using as the final localization step a spark chamber viewed by a TV digitizer it is easy to have imaging of complex patterns. This is applied to Cerenkov ring imaging and (K,π) separation with 3σ up to 320 GeV is envisaged. The properties of various photo-ionizable vapours have been studied. By combining a scintillation xenon chamber with a photoionization wire chamber, a resolution of 8.3% (FWHM) has been obtained, by using tetrakis(dimethylamine)- ethylene vapour, for 5.9 keV X-rays.