The CLEO detector has been upgraded to include a state of the art particle
identification system, based on the Ring Imaging Cherenkov detector (RICH)
technology, in order to take data at the upgraded CESR electron positron co
llider. The expected performance as well as the preliminary results are rev
iewed from an engineering run during the first few months of operation of t
he CLEO III detector. (C) 2001 Elsevier Science B.V. All rights reserved.