Status and R&D development of Photon Calorimeter G. Atoian, S. Dhawan, V. Issakov, A. Poblaguev, M. Zeller, Physics Department, Yale University, New Haven, CT G.I. Britvich, S. Chernichenko, I. Shein and A. Soldatov Institute for High Energy Physics, Protvino, Russia O. Karavichev, T. Karavicheva and V. Marin Institute for Nuclear Research of Russian Academy of Sciences, Moscow, Russia Photon Calorimeter for KOPIO The requirements of the KOPIO Photon Calorimeter: Energy resolution - 3[%]/ E. Time resolution - 90[psec]/ E. Photon detection inefficiency (due to holes-cracks) - Active area 5.3 m 2 Granularity - 11 11 cm 2. Radiation length - 16X 0 (18X 0 including Preradiator). Physical length - 60 cm. The Shashlyk technique satisfies the KOPIO requirements. All sizes are millimeters The design innovations: New scintillator tile (BASF143E + 1.5%pTP %POPOP produced by IHEP) with improved optical transparency and improved surface quality. The light yield is now ~ 60 photons per 1 MeV of incident photon energy. Nonuniformity of light response across the module is