SCINTILLATION CRYSTAL INCLUDING A RARE EARTH HALIDE, AND A RADIATION DETECTION SYSTEM INCLUDING THE SCINTILLATION CRYSTAL
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 scintillation crystal comprising:
Ln( 1-y )RE y X 3 :Me 2+ , wherein:
Ln represents a rare earth element;
Me 2+ represents Sr, Ba, or any mixture thereof and has a concentration of at least approximately 0.0002 wt. %;
RE represents a different rare earth element;
y has a value in a range of 0 to 1; and
X represents a halogen.
2 . A radiation detection system comprising:
the scintillation crystal of claim 1 ; and
a photosensor optically coupled to the scintillation crystal.
3 . A scintillation crystal comprising:
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; and
the scintillation crystal has a property including:
for a radiation energy range of 60 keV to 356 keV, the scintillation crystal has an averaged value for a departure from perfect linearity of no less than approximately -0.35%;
for a radiation energy range of 2000 keV to 2600 keV, the scintillation crystal has an averaged value for a departure from perfect linearity of no greater than approximately 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 approximately 0.7%; or
any combination thereof.
4 . A scintillation crystal comprising:
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; and
an energy resolution ratio is an energy resolution of the scintillation crystal divided by a different energy resolution of a different scintillation crystal having a different composition, wherein the energy resolution ratio is:
no greater than approximately 0.970 for energies in a range of 60 to 729 keV;
no greater than approximately 0.950 for energies in a range of 122 keV to 2615 keV;
no greater than approximately 0.920 for energies in a range of 583 keV to 2615 keV;
no greater than approximately 0.900 for energies in a range of 662 keV to 2615 keV;
no greater than approximately 0.985 for an energy of 60 keV;
no greater than approximately 0.980 for an energy of 122 keV;
no greater than approximately 0.980 for an energy of 239 keV;
no greater than approximately 0.970 for an energy of 511 keV;
no greater than approximately 0.970 for an energy of 583 keV;
no greater than approximately 0.970 for an energy of 662 keV;
no greater than approximately 0.970 for an energy of 729 keV;
no greater than approximately 0.950 for an energy of 2615 keV; or any combination thereof.
5 to 8 . (canceled)
9 . 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 0.970 for energies in a range of 60 to 729 keV;
no greater than approximately 0.950 for energies in a range of 122 keV to 2615 keV;
no greater than approximately 0.920 for energies in a range of 583 keV to 2615 keV;
no greater than approximately 0.900 for energies in a range of 662 keV to 2615 keV;
no greater than approximately 0.985 for an energy of 60 keV;
no greater than approximately 0.980 for an energy of 122 keV;
no greater than approximately 0.980 for an energy of 239 keV;
no greater than approximately 0.970 for an energy of 511 keV;
no greater than approximately 0.970 for an energy of 583 keV;
no greater than approximately 0.970 for an energy of 662 keV;
no greater than approximately 0.970 for an energy of 729 keV;
no greater than approximately 0.950 for an energy of 2615 keV; or any combination thereof.
10 to 21 . (canceled)
22 . The scintillation crystal claim 4 , wherein an energy resolution for the scintillation crystal is determined from an energy spectrum obtained using the scintillation crystal, a photomultiplier tube, a window disposed between the scintillation crystal and the photomultiplier tube, and a multi-channel analyzer coupled to the photomultiplier tube,
wherein:
the scintillation crystal has a shape of a right circular cylinder with diameter of approximately 64 mm and length of approximately 75 mm, and the scintillation crystal is wrapped with a reflector on the sides and one end;
the window includes sapphire or quartz;
the photomultiplier tube includes a linearly focused, non-saturated photomultiplier; and
the multi-channel analyzer is configured to perform bi-polar shaping at a 0.25 micro-s shaping time; and
the energy resolution is no greater than approximately 6.40% at 122 keV, no greater than approximately 2.90% at 662 keV, no greater than approximatelyl.90% at 2615 keV, or any combination thereof.
23 . The scintillation crystal of claim 22 , wherein the energy resolution is no greater than approximately 6.40%.
24 . (canceled)
25 . The scintillation crystal of claim 22 , wherein the energy resolution is no greater than approximately 2.90% at 662 keV.
26 . (canceled)
27 . The scintillation crystal of claim 22 , wherein the energy resolution is no greater than approximately 1.90% at 2615 keV.
28 to 29 . (canceled)
30 . The scintillation crystal of claim 1 , wherein the scintillation crystal is doped with Sr.
31 . The scintillation crystal of claim 1 , wherein the Me 2+ content in the scintillation crystal is at least approximately 0.0002 wt. %, at least approximately 0.0005 wt. %, or at least approximately 0.001 wt. %.
32 . The scintillation crystal of claim 1 , wherein the Me 2+ content in the scintillation crystal is no greater than approximately 0.05 wt. %, no greater than approximately 0.03 wt. %, no greater than 0.02 wt. %, or no greater than approximately 0.009 wt. %.
33 - 36 . (canceled)
37 . The scintillation crystal of claim 3 , wherein the averaged value for the departure from perfect linearity (DFPL average ) is determined by:
DFPL
average
=
∫
E
lower
E
upper
DFPL
(
E
i
)
·
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.
38 . (canceled)
39 . The scintillation crystal of claim 1 , wherein:
Ln includes La, Gd, Lu, or any mixture thereof, and
RE includes Ce, Eu, Pr, Tb, Nd, or any mixture thereof.
40 - 47 . (canceled)
48 . The scintillation crystal of claim 3 , 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 0.970 for energies in a range of 60 to 729 keV;
no greater than approximately 0.950 for energies in a range of 122 keV to 2615 keV;
no greater than approximately 0.920 for energies in a range of 583 keV to 2615 keV;
no greater than approximately 0.900 for energies in a range of 662 keV to 2615 keV;
no greater than approximately 0.985 for an energy of 60 keV;
no greater than approximately 0.980 for an energy of 122 keV;
no greater than approximately 0.980 for an energy of 239 keV;
no greater than approximately 0.970 for an energy of 511 keV;
no greater than approximately 0.970 for an energy of 583 keV;
no greater than approximately 0.970 for an energy of 662 keV;
no greater than approximately 0.970 for an energy of 729 keV;
no greater than approximately 0.950 for an energy of 2615 keV; or any combination thereof.
49 . The scintillation crystal of claim 1 , wherein the scintillation crystal is doped with Ba.
50 . The scintillation crystal of claim 3 , further comprising Me 2+ , wherein an Me 2+ content in the scintillation crystal is at least approximately 0.0002 wt. %, at least approximately 0.0005 wt. %, or at least approximately 0.001 wt. %.
51 . The scintillation crystal of claim 50 , wherein the Me 2+ content in the scintillation crystal is no greater than approximately 0.05 wt. %, no greater than approximately 0.03 wt. %, no greater than 0.02 wt. %, or no greater than approximately 0.009 wt. %.
52 . The scintillation crystal of claim 4 , further comprising Me 2+ , wherein an Me 2+ content in the scintillation crystal is at least approximately 0.0002 wt. %, at least approximately 0.0005 wt. %, or at least approximately 0.001 wt. %.
53 . The scintillation crystal of claim 52 , wherein the Me 2+ content in the scintillation crystal is no greater than approximately 0.05 wt. %, no greater than approximately 0.03 wt. %, no greater than 0.02 wt. %, or no greater than approximately 0.009 wt. %.