Progress on avalanche photodiodes for the CMS electromagnetic calorimeter

Avalanche Photodiodes have been chosen as photon sensors for the CMS electromagnetic calorimeter. Progress in the relevant properties of these devices are discussed, with special attention to their application coupled to lead tungstate crystals. The LHC is a hard environment for what concerns the radiation levels in the detectors, so the radiation resistance of the APD has been investigated. The damage and recovery dynamics have been studied according to a possible LHC running schedule.