In high energy physics experiments,large arrays of scintillation crystals have b een used in electromagnetic calorimeters for precision measurements of photons a nd electrons.The large crystal calorimeters and their use has been a key factor in the high energy physics programs.Table 1 lists parameters of crystal calorime ter projects of the past (Crystal Ball),present(L3) and future (CMS) in high ene rgy physics.In future high energy collider,however,scintillating crysta ls face a new challenge:the radiation damage caused by the increased background radiation level.It would reach about 1000 rad/day for lead tungstate (PbWO 4) crystal at LHC.Lead tungstate is a new fast and dense scintillating crystal and has been s elected as scintillator for the construction of calorimeter in CMS experiment of Large Hadron Collider (LHC) at CERN(European Organization for Nuclear Research ) next century.82000 large sized PWO scintillating crystals will be assembled in the calorimeter of the CMS experiment,and they will be produced both in China a nd in Russia from now until to 2004.
FENG Xi qi (Laboratory of Functional Inorganic Materials,Shanghai Institute of Ceramics,Chi nese Academy of Sciences,Shanghai 200050,China)
