Current achievements of the DELPHI ring imaging Cherenkov detector

The DELPHI experiment has already collected 2.5 million Z0 decays with the ring imaging Cherenkov detector (RICH) operational. This detector, covering most of the solid angle, is designed to perform π/K separation from 0.8 to 20 GeV/c and K/p separation from 0.8 to 35 GeV/c. After a brief detector description we discuss the actual operating conditions, the data monitoring and the signal treatment. The collected data from Z0 decays and the detector response to signals from the calibration system are used to evaluate the performance of the RICH system. (orig.)