Method of forming a scintillation crystal including a rare earth halide
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, RE is Ce, and the scintillation crystal is doped with Sr, Ba, or a mixture thereof at a concentration of at least approximately 0.0002 wt. %. In another embodiment, the scintillation crystal can have unexpectedly improved linearity and unexpectedly improved energy resolution properties. In a further embodiment, a radiation detection system can include the scintillation crystal, a photosensor, and an electronics device. Such a radiation detection system can be useful in a variety of radiation imaging applications.
1. A method, comprising:
placing into a crucible precursors including:
a rare earth halide precursor; and
a dopant precursor that includes a strontium halide, a barium halide, or any combination thereof;
melting the precursors to form a melt;
contacting the melt with a seed crystal;
using the seed crystal to form a scintillation crystal from the melt, wherein the scintillation crystal comprises La (1-y) RE y X 3 :Me 2+ , wherein:
RE represents a rare earth element other than La;
y has a value in a range of 0 to 0.5;
X represents a halogen; and
Me 2+ represents Sr, Ba, or any mixture thereof and has a concentration in a range of 0.0002 wt. % to 0.05 wt. %; and
roughening a surface of the scintillation crystal.
2. A method, comprising:
placing into a crucible precursors including:
a rare earth halide precursor; and
a dopant precursor that includes a strontium halide, a barium halide, or any combination thereof;
melting the precursors to form a melt;
contacting the melt with a seed crystal; and
using the seed crystal to form a scintillation crystal from the melt, wherein the scintillation crystal comprises La (1-y) RE y X 3 :Me 2+ , wherein:
RE represents a rare earth element other than La;
y has a value in a range of 0 to 0.5;
X represents a halogen; and
Me 2+ represents Sr, Ba, or any mixture thereof and has a concentration in a range of 0.0002 wt. % to 0.05 wt. %.
3. The method of claim 2 , wherein the scintillation crystal has a property including:
for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an average value for a departure from perfect linearity of no less than −0.35%;
for a radiation energy range of 2000 keV to 2600 keV, the scintillation crystal has an average value for a departure from perfect linearity of no greater than 0.07%;
for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an absolute value for a furthest departure from perfect linearity of no greater than 0.7%; or
any combination thereof.
4. The method of claim 3 , wherein the average value for the departure from perfect linearity (DFPL average ) is determined by:
DFPL
average
=
∫
E
lower
E
upper
DFPL
(
E
i
)
·
ⅆ
E
i
E
upper
-
E
lower
,
where
DFPL(Ei) is DFPL at energy E i ;
E upper is the upper limit of the energy range; and
E lower is the lower limit of the energy range.
5. The method of claim 2 , wherein the concentrations of Me 2+ is no greater than 0.03 wt. %.
6. The method of claim 5 , wherein y has a value in a range of 0.0001 to 0.2.
7. The method of claim 2 , wherein RE is Ce.
8. The method of claim 7 , wherein y has a value in a range of 0.0001 to 0.2.
9. The method of claim 2 , wherein Me 2+ represents Sr.
10. The method of claim 2 , wherein Me 2+ represents Ba.
11. The method of claim 2 , wherein Me 2+ does not include any divalent metal element other than Sr, Ba, or any combination thereof.
12. The method of claim 2 , wherein the concentration of Me 2+ is in a range of 0.005 wt. % to 0.02 wt. %.
13. The method of claim 2 , further comprising placing the scintillation crystal within casing.
14. The method of claim 13 , placing an optical interface adjacent to a surface of the scintillation crystal.
15. The method of claim 14 , further comprising placing a photosensor adjacent to the optical interface, wherein the optical interface is disposed between and optically couples the scintillation crystal and the photosensor to each other.
16. A method, comprising:
placing into a crucible precursors including:
LaBr 3 ;
CeBr 3 ; and
a dopant precursor that includes SrBr 2 , BaBr 2 , or any combination thereof;
melting the precursors to form a melt;
contacting the melt with a seed crystal; and
pulling a scintillation crystal from the melt, wherein the scintillation crystal comprises wherein the scintillation crystal comprises La (1-y) Ce y Br 3 :Me 2+ ,
wherein:
y has a value in a range of approximately 0.001 to 0.2; and
Me 2+ represents Sr, Ba, or any mixture thereof and has a concentration in a range of 0.0002 wt. % to 0.05 wt. %.
17. The method of claim 16 , wherein the scintillation crystal has a property including:
for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an average value for a departure from perfect linearity of no less than −0.35%;
for a radiation energy range of 2000 keV to 2600 keV, the scintillation crystal has an average value for a departure from perfect linearity of no greater than 0.07%;
for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an absolute value for a furthest departure from perfect linearity of no greater than 0.7%; or
any combination thereof.
18. The method of claim 17 , wherein the average value for the departure from perfect linearity (DFPL average ) is determined by:
DFPL
average
=
∫
E
lower
E
upper
DFPL
(
E
i
)
·
ⅆ
E
i
E
upper
-
E
lower
,
where
DFPL(Ei) is DFPL at energy E i ;
E upper is the upper limit of the energy range; and
E lower is the lower limit of the energy range.
19. The method of claim 16 , wherein the concentration of Me 2+ is in a range of 0.005 wt. % to 0.009 wt. %.
20. The method of claim 16 , further comprising roughening a surface of the scintillation crystal.