High-quality lead tungstate crystals available for EM-calorimetry in high-energy physics

Even at present time there is a strong interest and demand for high quality lead tungstate crystals (PbWO
4
, PWO) for electromagnetic (EM) calorimetry. PWO is implemented into the EM calorimeter of the CMS-ECAL detector at LHC [1] and required for the completion of the PANDA EMC [2] as well as various detector projects under discussion at Jefferson Lab or BNL in the States. The successful mass production of PWO using the Czochralski method was stopped after bankruptcy of the Bogoroditsk Technical Chemical Plant (BTCP) in Russia as the major producer so far. The Shanghai Institute of Ceramics, Chinese Academy of Science (China) was considered as an alternative producer using the modified Bridgman method. The company CRYTUR (Turnov, Czech Republic) with good experience in the development and production of different types of inorganic oxide crystals has re-started end of 2014 the development of lead tungstate for the mass production based again on the Czochralski method. An impressive progress was achieved since then. The growing technology was optimized to produce full size samples with the quality meeting the PANDA-EMC specifications for PWO-II. We will present a detailed progress report on the research program in collaboration with groups at Orsay and JLab. Full size crystals part of a pre-production run will be characterized with respect to optical performance, light yield, kinetics and radiation hardness.