The ring imaging detector for CLEO III

The CLEO detector will undergo major improvements in conjunction with a high luminosity upgrade of the CESR electron positron collider, that should increase the luminosity of this machine by a factor of 10. The most innovative feature of the planned CLEO detector is the addition of a state of the art particle identification system, based on a proximity focused Ring Imaging Cherenkov detector. The goal is to achieve good hadron identification at all the momenta relevant to the study of decays of B mesons produced at the upsilon(4S) resonance. This detector design will be discussed, including details of the mechanical design and the readout electronics. The performance of a prototype module will be described