The CLEO III upgrade

The electron storage ring CESR at Cornell University is presently undergoing a major upgrade together with its B-physics detector CLEO. Improved focusing and superconducting cavities will increase the luminosity of the collider to more than 2×1033 cm2 s−1. To accommodate the necessary accelerator elements the tracking region of CLEO has to be rebuilt. The new tracking system consists of a four-layer silicon vertex detector and a large volume drift chamber, which also provides dE/dx particle identification information. The CLEO III upgrade also includes a new particle identification system which allows full exploitation of the possibilities provided by the upgraded accelerator. This PID system is a proximity focusing RICH with lithium fluoride radiators and multi-wire chambers filled with a methane/triethylamine mixture to detect UV Cherenkov photons. Installation of the new detector elements in the CLEO detector is taking place during summer 1999.