The Ring Imaging Cherenkov detectors of DELPHI represent a large-scale part
icle identification system which covers almost the full angular acceptance
of DELPHI. The combination of liquid and gas radiators (C4F10, C5F12, and C
6F14) provides particle identification over the whole secondary particle mo
mentum spectrum at LEP I and LEP II. Continuing optimisation on the hardwar
e as well as on the online and offline software level have resulted in a st
able operation of the complete detector system for more than five years at
full physics performance. (C) 1999 Elsevier Science B.V. All rights reserve
d.