The forward ring imaging Cherenkov detector of DELPHI

Abstract The Forward Ring Imaging Cherenkov detector of the DELPHI experiment at LEP provides hadron identification at polar angles15° θ θ 6 F 14 and a volume of gaseous C 4 F 10 , in combination provide coverage of momenta up to 40 GeV/ c . A single array of photosensitive Time Projection Chambers registers the impact points of ultraviolet photons from both radiators. The design of the detector and of its readout system is described. First results obtained with a partly installed detector are reported.