Initial Performance of Cathode Strip Cylindrical Pwc's in Cleo at Cesr

A triplet of low mass cylindrical PWC's form the innermost element of the CLEO detector at the Cornell Electron Storage Ring (CESR). Each PWC has 2 cathodes of 144 azimuthal rings. Analogue signals from each ring enable center of charge reconstruction of the longitudinal (z) position of each avalanche. Structural elements are ρ = .06 g/cm3 polyurethane foam cylinders 1.2 cm thick. Each of the 720 anode wires and 864 cathode strips is instrummented with a charge integrator, ADC, and provision for read out to a computer. Preliminary observed z resolution of an individual PWC is ~ 300 μ for avalanches from e+e- annihilation events. The PWC's are also an important element in the fast trigger to discriminate against cosmic rays, and are used to identify beam-gas and beam-wall background events.