The Cleo Photon Shower Detector

We describe an electromagnetic shower detector which measures photon energies and positions, and provides charged particle tracking over a solid angle of 50% of 47π in the CLEO magnetic detector at the Cornell Electron Storage Ring. The detector is segmented into octants, each made of interleaved layers of proportional tubes and lead. The performance of the detector in an electron test beam and in initial e+e- annihilation experiments is discussed.