CsI(Tl) scintillator crystal including multi valence cations to reduce afterglow, and a radiation detection apparatus including the scintillation crystal

Patent metadata

Field	Value
Publication number	US-11249202-B2
Application number	US-202017082460-A
Country	US
Kind code	B2
Filing date	Oct 28, 2020
Priority date	Oct 28, 2019
Publication date	Feb 15, 2022
Grant date	Feb 15, 2022

Abstract

A scintillation crystal can include a cesium halide that is co-doped with thallium and another element. In an embodiment, the scintillation crystal can include CsX:Tl, Me, where X represents a halogen, and Me represents a dopant selected from the group consisting of chromium (Cr), zirconium (Zr), cobalt (Co), manganese (Mn), cadmium (Cd), dysprosium (Dy), thulium (Tm), tantalum (Ta), and erbium (Er), the dopant concentration of the element selected from the group consisting of chromium (Cr), zirconium (Zr), cobalt (Co), manganese (Mn), cadmium (Cd), dysprosium (Dy), thulium (Tm), tantalum (Ta), and erbium (Er) in the scintillation crystal is in a range of 1×10 −7 mol % to 0.5 mol %. In a particular embodiment, the scintillation crystal may have a cesium iodide host material, a first dopant including a thallium cation, and a second dopant including a cation.

First claim

What is claimed is:

1. A scintillator crystal comprising:
a cesium iodide host material;
a first dopant comprising a thallium cation, a molar concentration of said first dopant being less than 10%; and
a second dopant selected from the group consisting of chromium (Cr), zirconium (Zr), cobalt (Co), manganese (Mn), cadmium (Cd), dysprosium (Dy), thulium (Tm), tantalum (Ta), and erbium (Er), the dopant concentration of the element selected from the group consisting of chromium (Cr), zirconium (Zr), cobalt (Co), manganese (Mn), cadmium (Cd), dysprosium (Dy), thulium (Tm), tantalum (Ta), and erbium (Er) is at least partially in its 3+ or 2+ or 4+ or 5+ oxidation state, wherein the quantity of the second dopant in the scintillator comprises between 1×10 −7 mol % and 0.1 mol %, wherein the scintillator crystal has a light output intensity of less than 0.3% at 500 ms after exposure to an X-ray irradiation, relative to a light output intensity measured during the X-ray irradiation.

2. The scintillator crystal of claim 1 , further comprising a third dopant, and wherein the third dopant comprises an oxidation state different from the second dopant.

3. The scintillator crystal of claim 1 , further comprising a third dopant, and wherein the second dopant comprises trivalent oxidation state and the third dopant comprises divalent oxidation state.

4. The scintillator crystal of claim 1 , wherein the second dopant selected from the group consisting of chromium (Cr), cobalt (Co), manganese (Mn), and cadmium (Cd) is at least partially in its 2+ oxidation state.

5. The scintillator crystal of claim 1 , wherein the second dopant selected from the group consisting dysprosium (Dy), thulium (Tm), and erbium (Er) is at least partially in its 3+ oxidation state.

6. The scintillator crystal of claim 1 , wherein the second dopant selected from the group consisting of zirconium (Zr) is at least partially in its 4+ oxidation state.

7. The scintillator crystal of claim 1 , wherein the second dopant selected from the group consisting of tantalum (Ta) is at least partially in its 5+ oxidation state.

8. The scintillator crystal of claim 1 , wherein the scintillator crystal comprises at least 9×10 −4 mol % of the second dopant.

9. The scintillator crystal of claim 1 , wherein the scintillator crystal comprises less than 1×10 −3 mol % second dopant and wherein the scintillator crystal has a light output intensity of less than 0.5% at 100 ms after exposure to an X-ray irradiation, relative to a light output intensity measured during the X-ray irradiation.

10. The scintillator crystal of claim 1 , wherein the scintillator crystal comprises less than 1×10 −3 mol % second dopant and.

11. The scintillator crystal of claim 1 , wherein the scintillator crystal contains more than 1×10 −6 mol % of a co-dopant cation capable of existing in more than one oxidation state within the crystal matrix.

12. The scintillator crystal of claim 1 , wherein the scintillator crystal comprises no greater than 0.1 mol % of the second dopant.

13. A scintillator crystal comprising:
a cesium iodide host material;
a first dopant comprising a thallium cation, a molar concentration of said first dopant being less than 10%; and
a second dopant comprising a chromium cation, the second dopant resulting in the scintillator having a reduced afterglow, wherein the scintillator crystal has a light output intensity of less than 0.3% at 500 ms after exposure to an X-ray irradiation, relative to a light output intensity measured during the X-ray irradiation.

14. The scintillator crystal of claim 13 , wherein the quantity of the chromium in the scintillator crystal comprises between 1×10 −7 mol % and 1×10 −3 mol % chromium.

15. The scintillator crystal of claim 13 , wherein the scintillator crystal comprises less than 1×10 −3 mol % chromium and wherein the scintillator crystal has a light output intensity of less than 0.3% at 100 ms after exposure to an X-ray irradiation, relative to a light output intensity measured during the X-ray irradiation.

16. The scintillator crystal of claim 13 , wherein the scintillator crystal comprises less than 1×10 −3 mol % chromium and wherein the scintillator crystal has a light output intensity of less than 0.2% at 500 ms after exposure to an X-ray irradiation, relative to a light output intensity measured during the X-ray irradiation.

17. A radiation detection apparatus comprising:
a housing;
a scintillator within the housing, the scintillator comprising:
a cesium iodide host material;
a first dopant comprising a thallium cation, a molar concentration of said first dopant being less than 10%; and
a second dopant selected from the group consisting of chromium (Cr), zirconium (Zr), cobalt (Co), manganese (Mn), cadmium (Cd), dysprosium (Dy), thulium (Tm), tantalum (Ta) and erbium (Er), the dopant concentration of the element selected from the group consisting of chromium (Cr), zirconium (Zr), cobalt (Co), manganese (Mn), cadmium (Cd), dysprosium (Dy), thulium (Tm), tantalum (Ta) and erbium (Er), the second dopant resulting in the scintillator having a reduced afterglow, wherein the scintillator crystal has a light output intensity of less than 0.3% at 500 ms after exposure to an X-ray irradiation, relative to a light output intensity measured during the X-ray irradiation.

18. The radiation detection apparatus of claim 17 , a second dopant comprising a zirconium cation, the second dopant resulting in the scintillator having a reduced afterglow.

19. The radiation detection apparatus of claim 18 , wherein the afterglow is reduced by at least 30%.

20. The radiation detection apparatus of claim 17 , wherein the scintillator crystal comprises no greater than 0.1 mol % of the second dopant.

Assignees

• Saint Gobain Ceramics

Inventors

• Meng Fang
• Menge Peter R

Classifications

• G01T1/208

  Circuits specially adapted for scintillation detectors, e.g. for the photo-multiplier section · CPC title

• G01T1/202 Primary

  the detector being a crystal · CPC title

• G01T1/2023 Primary

  Selection of materials · CPC title

• G01T1/2018

  Scintillation-photodiode combinations · CPC title

• G21K4/00

  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) · CPC title