Method of forming a scintillation crystal and a radiation detection apparatus including a scintillation crystal including a rare earth halide

• US 10,203,421 B2
• Filed: 03/22/2016
• Issued: 02/12/2019
• Est. Priority Date: 10/28/2012
• Status: Active Grant

• Current Assignee: Stichting Voor de Technische Wetenschappen, Technische Universiteit Delft
• Original Assignee: Stichting Voor de Technische Wetenschappen, Universite De Berne
• Inventors: Dorenbos, Pieter, Kramer, Karl W.
• Primary Examiner(s): Kim, Christine S.
• Application Number:
  US15/077,042
• Publication Number:
  US 20160200972A1
• Time in Patent Office: 1,057 Days
• 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 Ca halide precursor;

melting the precursors to form a melt, wherein a concentration of the Ca halide is at least 0. 02wt. %;

forming a scintillation crystal including Ln(_1-y)RE_yX₃;

Ca, 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

optically coupling an optical interface to the scintillation crystal.

2. The method of claim 1, wherein RE is Ce.

3. The method of claim 2, wherein Ln is La.

4. The method of claim 3, wherein X is Br.

5. The method of claim 2, wherein y is 1.0 f.u.

6. The method of claim 1, wherein the concentration of the Ca halide in the melt is no greater than 1.0 wt. %.

7. The method of claim 1, wherein y is no greater than 0.5 and at least 0. 005.

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

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 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 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 8.0%;

or

for radiation energy range of 30 keV to 60 keV, the scintillation crystal has the PR _{dev average} of no greater than 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 0.95 for an energy of 8 keV;

no greater than 0.95 for an energy of 13 keV;

no greater than 0.95 for an energy of 17 keV;

no greater than 0.95 for an energy of 22 keV;

no greater than 0.95 for an energy of 26 keV;

no greater than 0.95 for an energy of 32 keV;

or

no greater than 0.97 for an energy of 44 keV.

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

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

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

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

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

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

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