Divalent fluoride doped cerium fluoride scintillator

• US 5,039,858 A
• Filed: 01/31/1990
• Issued: 08/13/1991
• Est. Priority Date: 01/31/1990
• Status: Expired due to Term

• Current Assignee: EM Industries, Inc., Fermi Research Alliance, LLC
• Original Assignee: Universities Research Association Incorporated Fermi National Accelerator Laboratory KIRK & Pine Roads Batavia IL A Not-For-Profit Corporation of DC
• Inventors: Sparrow, Robert W., Anderson, David F.
• Primary Examiner(s): Hannaher, Constantine
• Application Number:
  US07/473,056
• Time in Patent Office: 559 Days
• Field of Search: 252/301.4 H, 250/363.03
• US Class Current: 250/363.03
• CPC Class Codes: G01T 1/202 the detector being a crystal

Abstract

The use of divalent fluoride dopants in scintillator materials comprising cerium fluoride is disclosed. The preferred divalent fluoride dopants are calcium fluoride, strontium fluoride, and barium fluoride. The preferred amount of divalent fluoride dopant is less than about two percent by weight of the total scintillator. Cerium fluoride scintillator crystals grown with the addition of a divalent fluoride have exhibited better transmissions and higher light outputs than crystals grown without the addition of such dopants. These scintillators are useful in radiation detection and monitoring applications, and are particularly well suited for high-rate applications such as positron emission tomography (PET).

Claims

1. A scintillator comprising cerium fluoride and a divalent fluoride dopant, said scintillator having a fast component with a decay constant of about 5 nanoseconds and a slow component with a decay constant of about 30 nanoseconds.

2. The scintillator of claim 1 wherein said dopant is calcium fluoride.

3. The scintillator of claim 1 wherein said dopant is strontium fluoride.

4. The scintillator of claim 1 wherein said dopant is barium fluoride.

5. The scintillator of claim 1 wherein said dopant is present in an amount less than about two percent by weight of the total scintillator.

6. The scintillator of claim 1 wherein said scintillator is used to detect ionizing radiation.

7. The scintillator of claim 6 wherein said ionizing radiation is in the form of high energy photons.

8. The scintillator of claim 6 wherein said ionizing radiation is in the form of gamma rays.

9. The scintillator of claim 1 wherein said scintillator is used in position emission tomography.

10. A scintillator comprising cerium fluoride and a scintillation-enhancing dopant represented by the formula XF₂, wherein X is selected from the group consisting of calcium, strontium and barium.

11. The scintillator of claim 10 wherein said dopant is present in an amount less than about two percent by weight of the total scintillator.

12. The scintillator of claim 10 wherein said scintillator is used to detect ionizing radiation.

13. The scintillator of claim 12 wherein said ionizing radiation is in the form of high energy photons.

14. The scintillator of claim 12 wherein said ionizing radiation is in the form of gamma rays.

15. The scintillator of claim 10 wherein said scintillator is used in position emission tomography.

16. A method of preparing a scintillator comprising cerium fluoride comprising adding a scintillation-enhancing divalent fluoride dopant.

17. The method of claim 16 wherein said dopant is calcium fluoride.

18. The method of claim 16 wherein said dopant is strontium fluoride.

19. The method of claim 16 wherein said dopant is barium fluoride.

20. The method of claim 16 wherein said dopant is added in an amount less than about two percent by weight of the total scintillator.

21. A camera for use in positron emission tomography comprising a scintillator comprising cerium fluoride and a divalent fluoride dopant, said scintillator having a fast component with a decay constant of about 5 nanoseconds and a slow component with a decay constant of about 30 nanoseconds.

22. The camera of claim 21 wherein said dopant is represented by the formula XF₂, wherein X is selected from the group consisting of calcium, strontium and barium.

23. The camera of claim 21 wherein said dopant is present in an amount less than about two percent by weight of the total scintillator.

24. The method of detecting ionizing radiation which comprises using a scintillator comprising cerium fluoride and a divalent fluoride dopant, said scintillator having a fast component with a decay constant of about 5 nanoseconds and a slow component with a decay constant of about 30 nanoseconds.

25. The method of claim 24 wherein said ionizing radiation is in the form of high energy photons.

26. The method of claim 25 wherein said ionizing radiation is in the form of gamma rays.

27. The method of claim 24 wherein said dopant is represented by the formula XF₂, wherein X is selected from the group consisting of calcium, strontium and barium.

28. The method of claim 24 wherein said dopant is present in an amount less than about two percent by weight of the total scintillator.

29. The method of performing positron emission tomography which comprises using a scintillator comprising cerium fluoride and a divalent fluoride dopant, said scintillator having a fast component with a decay constant of about 5 nanoseconds and a slow component with a decay constant of about 30 nanoseconds.

30. The method of claim 29 wherein said dopant is represented by the formula XF₂, wherein X is selected from the group consisting of calcium, strontium and barium.

31. The method of claim 29 wherein said dopant is present in an amount less than about two percent by weight of the total scintillator.