Scintillation crystal including a co-doped sodium halide
A scintillation crystal can include a sodium halide that is co-doped with thallium and another element. In an embodiment, the scintillation crystal can include NaX:Tl, Me, wherein X represents a halogen, and Me represents a Group 1 element, a Group 2 element, a rare earth element, or any combination thereof. In a particular embodiment, the scintillation crystal has a property including, for radiation in a range of 300 nm to 700 nm, an emission maximum at a wavelength no greater than 430 nm; or an energy resolution less than 6.4% when measured at 662 keV, 22° C., and an integration time of 1 microsecond. In another embodiment, the co-dopant can be Sr or Ca. The scintillation crystal can have lower energy resolution, better proportionality, a shorter pulse decay time, or any combination thereof as compared to the sodium halide that is doped with only thallium.
1. A well logging device, comprising:
a scintillation crystal in the well logging device, the scintillation crystal comprising NaX:Tl, Me 2+ , and RE, wherein:
X represents a halogen;
Me 2+ represents a divalent metal element;
RE represents a rare earth element;
Tl has a dopant concentration in a range of 1×10 −5 mol % to 0.2 mol %;
Me 2+ has a dopant concentration greater than a dopant concentration of Tl; and the scintillation crystal has a pulse decay time that is at least 5% less than a pulse decay time a NaI:Tl crystal when the scintillation crystal and the NaI:Tl crystal are measured at 22° C. and exposed to gamma radiation having an energy of 662 keV.
2. The well logging device of claim 1 , wherein RE has a concentration of at least 1×10 −4 mol %.
3. The well logging device of claim 1 , wherein X is a combination of I and Br.
4. The well logging device of claim 1 , wherein X is I.
5. The well logging device of claim 1 , wherein RE is Sc, Y, Lu, Yb, or any combination thereof.
6. The well logging device of claim 1 , wherein the scintillation crystal has an emission maximum at a wavelength no greater than 430 nm.
7. A medical imaging device, comprising:
a scintillation crystal in the medical imaging device, the scintillation crystal comprising NaX:Tl, Me 2+ , wherein:
X represents a halogen;
Me 2+ represents a divalent metal element; and
Tl has a dopant concentration in a range of 1×10 −5 mol % to 0.2 mol %; wherein the scintillation crystal has a property including:
an emission maximum at a wavelength no greater than 430 nm.
8. The medical imaging device of claim 7 , wherein Me 2+ is Sr having a concentration no greater than 0.9 mol %.
9. The medical imaging device of claim 8 , wherein Sr has a concentration in a range of 0.01 mol % to 0.2 mol %.
10. The medical imaging device of claim 7 , wherein the scintillation crystal has a greater light yield as compared to a NAI:Tl crystal when the scintillation crystal and the NaI:Tl crystal are measured at 22° C.
11. The medical imaging device of claim 7 , wherein the scintillation crystal has an energy resolution less than 6.4% when measured at 662 keV, 22° C., and an integration time of 1 microsecond.
12. The medical imaging device of claim 7 , wherein at energies in the range of 32 keV to 81 keV, the scintillation crystal has an average relative light yield as normalized to a light yield at 2615 keV of no greater than 1.15.
13. The medical imaging device of claim 7 , wherein Me 2+ is Ca having a concentration no greater than 0.9 mol %.
14. The medical imaging device of claim 13 , wherein Ca has a concentration in a range of 0.01 mol % to 0.2 mol %.
15. The medical imaging device of claim 14 , wherein Me has a concentration in a range of 0.01 mol % to 0.9 mol %.
16. The medical imaging device of claim 15 , wherein Tl has a concentration in a range of 1×10 −4 mol % to 0.2 mol %.
17. A medical imaging device, comprising:
a scintillation crystal in the medical imaging device, the scintillation crystal comprising NaX:Tl, Me, wherein:
X represents a halogen;
Me represents a Group 1 element, a Group 2 element, or any combination thereof;
Tl has a dopant concentration in a range of 1×10 −5 mol % to 0.2 mol %; and
Me has a dopant concentration greater than the dopant concentration of Tl; and
the scintillation crystal has a property including:
an energy resolution less than 6.4% when measured at 662 keV, 22° C., and an integration time of 1 microsecond; or
a pulse decay time that is less than another scintillation crystal that has a composition of NaX:Tl.
18. The medical imaging device of claim 17 , wherein the scintillation crystal has an energy resolution less than 6.4% when measured at 662 keV, 22° C., and an integration time of 1 microsecond.
19. The medical imaging device of claim 17 , wherein at energies in the range of 32 keV to 81 keV, the scintillation crystal has an average relative light yield as normalized to a light yield at 2615 keV of no greater than 1.15.
20. The medical imaging device of claim 17 , wherein at energies in the range of 122 keV to 511 keV, the scintillation crystal has an average relative light yield as normalized to a light yield at 2615 keV no greater than 1.07.