METHOD OF FORMING A SCINTILLATION CRYSTAL AND A RADIATION DETECTION APPARATUS INCLUDING A SCINTILLATION CRYSTAL INCLUDING A RARE EARTH HALIDE

• US 20160200972A1
• Filed: 03/22/2016
• Published: 07/14/2016
• Est. Priority Date: 10/28/2012
• Status: Active Grant

• Current Assignee: Stichting Voor de Technische Wetenschappen, Technische Universiteit Delft
• Original Assignee: Saint-Gobain Ceramics & Plastics Incorporated (Compagnie De Saint-Gobain), Stichting Voor de Technische Wetenschappen, Universite De Berne
• Inventors: Dorenbos, Pieter, Menge, Peter R., Ouspenski, Vladimir, Krmer, Karl W.
• Granted Patent: US 10,203,421 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: C09K 11/7772 Halogenides C09K11/7767 takes precedence
• CPC Class Codes: C09K 11/7773 with alkali or alkaline earth metal
• CPC Class Codes: G01T 1/2006 using a combination of a scintillator and photodetector which measures the means radiation intensity
• CPC Class Codes: G01T 1/2023 Selection of materials see provisionally also G01T1/202
• CPC Class Codes: G21K 2004/06 with a phosphor layer
• CPC Class Codes: G21K 4/00 Conversion screens for the conversion of the spatial distribution of X-rays or particle radiation into visible images, e.g. fluoroscopic screens photographic processes using X-ray intensifiers G03C5/17; discharge tubes comprising luminescent screens H01J1/62; cathode ray tubes for X-ray conversion with optical output H01J31/50

Abstract

A scintillation crystal can include Ln_(1-y)RE_yX₃, 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.

Claims

1. A method, comprising:

placing into a crucible precursors including;

a rare earth halide precursor; and

a dopant precursor that includes a halide of a Group 1 element or a Group 2 element;

melting the precursors to form a melt, wherein a concentration of all Group 1 and Group 2 halides is at least approximately 0.02 wt. %; and

forming a scintillation crystal including Ln_(1-y)RE_yX₃;

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

optically coupling an optical interface to the scintillation crystal.

2. The method of claim 1, wherein Me is Ca.

3. The method of claim 1, wherein Me is Li.

4. The method of claim 1, wherein the concentration of all Group 1 and Group 2 halides in the melt is no greater than approximately 1.0 wt. %.

5. The method of claim 1, wherein y is no greater than approximately 0.5 and at least approximately 0.005.

6. The method of claim 1, wherein y is in a range of approximately 0.01 to approximately 0.09.

7. The method of claim 1, wherein Ln is La, RE is Ce, and X is Br.

8. The method of claim 1, wherein y is approximately 1.0 f.u.

9. The method of claim 1, 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%

10. The method 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%.

11. The method 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.

12. The method of claim 11, wherein the energy resolution ratio is no greater than approximately 0.95 for the energy of 8 keV.

13. The method of claim 11, wherein the energy resolution ratio is no greater than approximately 0.95 for the energy of 13 keV.

14. The method of claim 11, wherein the energy resolution ratio is no greater than approximately 0.95 for the energy of 17 keV.

15. The method of claim 11, wherein the energy resolution ratio is no greater than approximately 0.95 for the energy of 22 keV.

16. The method of claim 11, wherein the energy resolution ratio is no greater than approximately 0.95 for the energy of 26 keV.

17. The method of claim 11, wherein an energy resolution ratio is no greater than approximately 0.95 for the energy of 32 keV.

18. The method of claim 1, further comprising optically coupling a photosensor to the optical interface.

19. 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;

forming a scintillation crystal including 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%; and

optically coupling an optical interface to the scintillation crystal.

20. The method of claim 19, further comprising optically coupling a photosensor to the optical interface.