Restart of the Production of High-Quality PbWO₄ Crystals for Calorimetry Applications

Abstract

Even presently there is a strong interest and demand for high-quality lead tungstate crystals (PbWO₄, PWO) for electromagnetic (EM) calorimetry. PWO is implemented into the EM calorimeter of the CMS-ECAL detector at LHC [1] and is required for the completion of the PANDA EMC [2] as well as various detector projects under discussion at Jefferson Lab or BNL in the United States. The mass production of PWO using the Czochralski method had to be stopped after bankruptcy of the Bogoroditsk Technical Chemical Plant (BTCP) in Russia as the major former producer. The company SICCAS (China) was initially considered as an alternative producer but using the modified Bridgman method. The company CRYTUR (Czech Republic) with good experience in the production of different types of inorganic oxide crystals has re-started end of 2014 the development of PWO for the mass production based on the Czochralski method. The growing technology was optimized to reach a quality meeting the PANDA-EMC specifications for PWO-II. We present a detailed progress report on full size crystals part of the pre-production with respect to the optical performance, light yield, kinetics and radiation hardness.