A Cherenkov ring reconstruction algorithm has been developed to determine t
he mean Cherenkov angle. It is used to study the response of the DELPHI RIC
H detectors and to identify particles. Results from the analysis of real an
d simulated data samples are presented. Finally, two different techniques f
or particle identification and their applications to physics analyses are d
escribed. (C) 1999 Elsevier Science B.V. All rights reserved.