Methods and Apparatus for Improved Gamma Spectra Generation

• US 20070187608A1
• Filed: 03/23/2007
• Published: 08/16/2007
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Dan Inbar
• Original Assignee: Dan Inbar
• Inventors: Inbar, Dan, Beer, Steve
• Granted Patent: US 7,820,977 B2
• Time in Patent Office: Days
• US Class Current: 250/362
• CPC Class Codes: G01T 1/167 Measuring radioactive content of objects, e.g. contamination whole body counters G01T1/163
• CPC Class Codes: G01V 5/281 detecting special nuclear material [SNM], e.g. Uranium-235, Uranium-233 or Plutonium-239

Abstract

A method of improving energy determination of a Gamma event which interacts with a segmented scintillation detector, the method comprising: identifying radiation events detected by a detector that are likely not to have deposited their full energy in the detector, based only on characteristics of said detected events; and treating the identified radiation events differently from other radiation events that are likely to have deposited their full energy in the detector.

Claims

1. A method of improving energy determination of a Gamma event which interacts with a segmented scintillation detector, the method comprising:

identifying radiation events detected by a detector that are likely not to have deposited their full energy in the detector, based only on characteristics of said detected events; and

treating the identified radiation events differently from other radiation events that are likely to have deposited their full energy in the detector.

2. A method according to claim 1 wherein identifying comprises determining the number of scintillations caused by a radiation event.

3. A method according to claim 2 wherein treating the identified events differently comprises rejecting radiation events causing a number of scintillations below a threshold number.

4. A method according to claim 1 wherein treating the identified events differently comprises rejecting radiation events causing a number of scintillations below a threshold number.

5. A method according to claim 1 wherein identifying events comprises estimating a position and time of scintillations caused by said interactions.

6. A method according to claim 5 wherein identifying is responsive to one or more characteristics chosen from the group consisting of (a) the number of scintillations associated with a given radiation event;

(b) the distance of a final scintillation associated with a given radiation event from a boundary of the detector;

(c) the time duration of a series of scintillations resulting from a radiation event;

or (d) the number of scintillations resulting from a given radiation event.

7. A method according to claim 6 wherein the event is rejected is the number of scintillations is below a given number.

8. A method according to claim 7 wherein identifying is responsive to at least one of (a) (b) or (c).

9. A method according to claim 7 wherein identifying is responsive to at least two of (a) (b) or (c).

10. A method according to claim 7 wherein identifying is responsive to all of (a), (b) and (c)

11. A method according to claim 6 wherein identifying is responsive to at least two of (a) (b), (c) or (d).

12. A method according to claim 6 wherein identifying is responsive to at least three of (a) (b), (c) or (d)

13. A method according to claim 6 wherein identifying is responsive to all of (a), (b), (c) and (d).

14. A method according to claim 6 wherein identifying comprises weighting a probability factor associated with each of said characteristics to provide a score.

15. A method according to claim 14 wherein treating differently comprises rejecting events having a weighted score below a given threshold.

16. A method according to claim 14 wherein treating differently comprising estimating the energy of said events and utilizing said events with the estimated energy to form an energy spectrum.

17. A method according to claim 9 wherein identifying comprises weighting a probability factor associated with each of said characteristics to provide a score.

18. A method according to claim 17 wherein treating differently comprises rejecting events having a weighted score below a given threshold.

19. A method according to claim 17 wherein treating differently comprising estimating the energy of said events and utilizing said events with the estimated energy to form a spectrum.

20. A method according to claim 10 wherein identifying comprises weighting a probability factor associated with each of said characteristics to provide a score.

21. A method according to claim 20 wherein treating differently comprises rejecting events having a weighted score below a given threshold.

22. A method according to claim 20 wherein treating differently comprising estimating the energy of said events and utilizing said events with the estimated energy to form a spectrum.

23. A method according to claim 11 wherein identifying comprises weighting a probability factor associated with each of said characteristics to provide a score.

24. A method according to claim 23 wherein treating differently comprises rejecting events having a weighted score below a given threshold.

25. A method according to claim 23 wherein treating differently comprising estimating the energy of said events and utilizing said events with the estimated energy to form an energy spectrum.

26. A method according to claim 12 wherein identifying comprises weighting a probability factor associated with each of said characteristics to provide a score.

27. A method according to claim 26 wherein treating differently comprises rejecting events having a weighted score below a given threshold.

28. A method according to claim 26 wherein treating differently comprising estimating the energy of said events and utilizing said events with the estimated energy to form a spectrum.

29. A method according to claim 14 wherein identifying comprises weighting a probability factor associated with each of said characteristics to provide a score.

30. A method according to claim 29 wherein treating differently comprises rejecting events having a weighted score below a given threshold.

31. A method according to claim 29 wherein treating differently comprising estimating the energy of said events and utilizing said events with the estimated energy to form an energy spectrum.

32. A method according to claim 1 wherein the scintillator is an organic scintillator.