The method for pulling large diameter single crystals with the abovesaid difficulties avoided is developed.Here the free melt surface does not depend on the growing crystal diameter and remains minimal during the whol...The method for pulling large diameter single crystals with the abovesaid difficulties avoided is developed.Here the free melt surface does not depend on the growing crystal diameter and remains minimal during the whole growing process.The essence of this method is that at the stage of radial crystal growth the melt level in the crucible of a variable cross-section(for instance,in a conical crucible)is raised.展开更多
Phosphor converts excitation energy into light,resulting in lumminescence.The luminescence caused by radiation is called scintillation.Since the discovery of the scintillation in NaI∶Tl crystal in 1948,a series of ma...Phosphor converts excitation energy into light,resulting in lumminescence.The luminescence caused by radiation is called scintillation.Since the discovery of the scintillation in NaI∶Tl crystal in 1948,a series of materials with profound scintillating characteristics have been developed and have found wide applications for radiation detection in different fields such as nuclear physics,high energy physics,medical diagnostic imaging,geophysics exploration,clandestine explosive finding and many industrial measuring systems. Inorganic scintillating crystals have superior characteristics over their organic counterparts and some kinds of ceramics,glasses and powders that do have their scintillation effects.We will confine ourselves mainly to inorganic scintillating crystals in this presentation..展开更多
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 u...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.展开更多
文摘The method for pulling large diameter single crystals with the abovesaid difficulties avoided is developed.Here the free melt surface does not depend on the growing crystal diameter and remains minimal during the whole growing process.The essence of this method is that at the stage of radial crystal growth the melt level in the crucible of a variable cross-section(for instance,in a conical crucible)is raised.
文摘Phosphor converts excitation energy into light,resulting in lumminescence.The luminescence caused by radiation is called scintillation.Since the discovery of the scintillation in NaI∶Tl crystal in 1948,a series of materials with profound scintillating characteristics have been developed and have found wide applications for radiation detection in different fields such as nuclear physics,high energy physics,medical diagnostic imaging,geophysics exploration,clandestine explosive finding and many industrial measuring systems. Inorganic scintillating crystals have superior characteristics over their organic counterparts and some kinds of ceramics,glasses and powders that do have their scintillation effects.We will confine ourselves mainly to inorganic scintillating crystals in this presentation..
文摘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.
