Inorganic Scintillator and Process for its Fabrication

Abstract

The inorganic scintillator of the invention is an inorganic scintillator capable of producing scintillation by radiation, which is a crystal comprising a metal oxide containing Lu, Gd, Ce and Si and belonging to space group C2/c monoclinic crystals, and which satisfies the condition specified by the following inequality (1A), wherein A Lu represents the number of Lu atoms in the crystal and A Gd represents the number of Gd atoms in the crystal. { A Lu /( A Lu +A Gd )}<0.50  (1A)

1 . A process for fabrication of an inorganic scintillator capable of producing scintillation by radiation, which is a crystal comprising a metal oxide containing Lu, Gd, Ce and Si and belonging to space group C2/c monoclinic crystals, and by satisfying the condition specified by the following inequality (1A):  
       { A   Lu /( A   Lu   +A   Gd )}<0.50  (1A)  
     wherein A Lu  represents the number of Lu atoms in the crystal and A Gd  represents the number of Gd atoms in the crystal, the process comprising: 
 a melting step in which the raw material for said inorganic scintillator is brought to a molten state by a melting method to obtain a melt,  
 a cooling and solidification step in which said melt is cooled to solidification to obtain a single crystal ingot, and  
 a cutting step in which said single crystal ingot is cut out to a prescribed shape and size.  
 
   
   
       2 . A process for fabrication of an inorganic scintillator according to  claim 1 , wherein at least a portion of a seed crystal is dipped in said melt prior to cooling and solidification of said melt in said cooling and solidification step, and a crystal is grown along a prescribed crystal plane of said seed crystal to obtain said single crystal ingot.  
   
   
       3 . A process for fabrication of an inorganic scintillator according to  claim 2 , wherein said seed crystal is a crystal comprising a metal oxide containing Lu, Gd and Si and belonging to space group C2/c monoclinic crystals.  
   
   
       4 . A process for fabrication of an inorganic scintillator according to  claim 3 , wherein said seed crystal satisfies the condition specified by the following inequality (3A).  
       { B   Lu /( B   Lu   +B   Gd )}<0.50  (3A)  
     wherein B Lu  represents the number of Lu atoms in the seed crystal and B Gd  represents the number of Gd atoms in the seed crystal.  
   
   
       5 . A process for fabrication of an inorganic scintillator according to  claim 4 , wherein said seed crystal satisfies the condition specified by the following inequality (4A).  
       0.10 <{B   Lu /( B   Lu   +B   Gd )}<0.40  (4A)  
   
   
       6 . A process for fabrication of an inorganic scintillator according to  claim 4 , wherein said metal oxide further comprises Y and said seed crystal satisfies the condition specified by the following inequality (3B).  
       {( B   Lu   +B   Y )/( B   Lu   +B   Y   +B   Gd )}<0.50  (3B)  
     wherein B Lu  represents the number of Lu atoms in the seed crystal, B Y  represents the number of Y atoms in the seed crystal and B Gd  represents the number of Gd atoms in the seed crystal.  
   
   
       7 . A process for fabrication of an inorganic scintillator according to  claim 6 , wherein said seed crystal satisfies the condition specified by the following inequality (4B).  
       0.10<{( B   Lu   +B   Y )/( B   Lu   +B   Y   +B   Gd )}<0.40  (4B)  
   
   
       8 . A process for fabrication of an inorganic scintillator according to  claim 2 , wherein said seed crystal is a crystal comprising a metal oxide containing Y and Si, and belonging to space group C2/c monoclinic crystals.  
   
   
       9 . A process for fabrication of an inorganic scintillator according to  claim 2 , wherein said seed crystal is a crystal comprising a metal oxide containing Lu and Si and essentially no Gd, and belonging to space group C2/c monoclinic crystals.