Specifications for Lead Tungstate Crystals Preproduction

After 3 years of extensive R&D the Bogoroditsk Techno-Chemical Plant in Russia is ready to enter a preproduction phase where 6000 Lead Tungstate crystals will be produced for the CMS electromagnetic calorimeter during a period of about 18 months. Although this is a demonstration test for the mass production, these crystals will have to be installed in the calorimeter and have therefore to comply with the very severe constraints imposed by the ambitious performance goal of the calorimeter in the high radiation environment of LHC. This paper describes and justifies the specifications for these preproduction crystals