Scintillation crystal including a rare earth halide, and a radiation detection apparatus including the scintillation crystal

Abstract

A scintillation crystal can include Ln (1-y) RE y X 3 , wherein Ln represents a rare earth element, RE represents a different rare earth element, y has a value in a range of 0 to 1, and X represents a halogen. In an embodiment, the scintillation crystal is doped with a Group 1 element, a Group 2 element, or a mixture thereof, and the scintillation crystal is formed from a melt having a concentration of such elements or mixture thereof of at least approximately 0.02 wt. %. In another embodiment, the scintillation crystal can have unexpectedly improved proportionality and unexpectedly improved energy resolution properties. In a further embodiment, a radiation detection apparatus can include the scintillation crystal, a photosensor, and an electronics device. Such a radiation detection apparatus can be useful in a variety of applications.

What is claimed is: 
     
         1 . A scintillation crystal comprising:
   Ln (1-y) RE y X 3 :Me,   
       wherein:
 Ln represents a rare earth element; 
 RE represents a different rare earth element; 
 y has a value in a range of 0 to 1; 
 X represents a halogen; 
 Me represents a Group 1 element, a Group 2 element, or any mixture thereof; and 
 the scintillation crystal is formed from a melt having a Me concentration of at least approximately 0.02 wt. %. 
 
     
     
         2 . A radiation detection apparatus comprising:
 a scintillation crystal including Ln (1-y) RE y X 3 :Me, wherein:   Ln represents a rare earth element;   RE represents a different rare earth element;   y has a value in a range of 0 to 1;   X represents a halogen;   Me represents a Group 1 element, a Group 2 element, or any mixture thereof; and   the scintillation crystal is formed from a melt having a Me concentration of at least approximately 0.02 wt. %; and   a photosensor optically coupled to the scintillation crystal.   
     
     
         3 . A scintillation crystal comprising:
 a rare earth halide, wherein:
 for a radiation energy range of 11 keV to 30 keV, the scintillation crystal has an nPR dev average  of no greater than approximately 8.0%; or 
 for a radiation energy range of 30 keV to 60 keV, the scintillation crystal has the nPR dev average  of no greater than approximately 3.6%. 
   
     
     
         4 . The scintillation crystal of  claim 1 , wherein Me is Ca. 
     
     
         5 . The scintillation crystal of  claim 1 , wherein Me is Li. 
     
     
         6 . The scintillation crystal of  claim 1 , wherein the melt has the Me concentration of at least approximately 0.08 wt. %, at least approximately 0.2 wt. %, or no greater than approximately 1.0 wt. %. 
     
     
         7 . The scintillation crystal of  claim 1 , wherein y is no greater than approximately 0.5 and at least approximately 0.005. 
     
     
         8 . The scintillation crystal of  claim 1 , wherein y is in a range of approximately 0.01 to approximately 0.09. 
     
     
         9 . The scintillation crystal of  claim 1 , wherein Ln is La, RE is Ce, and X is Br. 
     
     
         10 . The scintillation crystal of  claim 1 , wherein y is approximately 1.0 f.u. 
     
     
         11 . The scintillation crystal of  claim 10 , wherein for a radiation energy range of 13 keV to 30 keV, the scintillation crystal has a PR dev average  of no greater than approximately 14%, or for a radiation energy range of 30 keV to 60 keV, the scintillation crystal has a PR dev average  of no greater than approximately 8.0% 
     
     
         12 . The scintillation crystal of  claim 1 , wherein:
 for a radiation energy range of 11 keV to 30 keV, the scintillation crystal has a PR dev average  of no greater than approximately 8.0%; or   for a radiation energy range of 30 keV to 60 keV, the scintillation crystal has the PR dev average  of no greater than approximately 3.6%.   
     
     
         13 . The scintillation crystal of  claim 1 , wherein an energy resolution ratio is an energy resolution of the scintillation crystal divided by a different energy resolution of a different scintillation crystal of a different composition, wherein the energy resolution ratio is:
 no greater than approximately 0.95 for an energy of 8 keV;   no greater than approximately 0.95 for an energy of 13 keV;   no greater than approximately 0.95 for an energy of 17 keV;   no greater than approximately 0.95 for an energy of 22 keV;   no greater than approximately 0.95 for an energy of 26 keV;   no greater than approximately 0.95 for an energy of 32 keV; or   no greater than approximately 0.97 for an energy of 44 keV.   
     
     
         14 . The scintillation crystal of  claim 13 , wherein the energy resolution ratio is no greater than approximately 0.95 for the energy of 8 keV. 
     
     
         15 . The scintillation crystal of  claim 1 , wherein the energy resolution ratio is no greater than approximately 0.95 for the energy of 13 keV. 
     
     
         16 . The scintillation crystal of  claim 1  wherein the energy resolution ratio is no greater than approximately 0.95 for the energy of 17 keV. 
     
     
         17 . The scintillation crystal of  claim 1 , wherein the energy resolution ratio is no greater than approximately 0.95 for the energy of 22 keV. 
     
     
         18 . The scintillation crystal of  claim 1 , wherein the energy resolution ratio is no greater than approximately 0.95 for the energy of 26 keV. 
     
     
         19 . The scintillation crystal of  claim 1 , wherein an energy resolution ratio is no greater than approximately 0.95 for the energy of 32 keV. 
     
     
         20 . The radiation detection apparatus of  claim 2 , wherein the radiation detection apparatus is a medical imaging system or a well logging apparatus.