Detection of nuclear materials

• US 20060284094A1
• Filed: 02/06/2006
• Published: 12/21/2006
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Dan Inbar
• Original Assignee: Dan Inbar
• Inventors: Inbar, Dan
• Granted Patent: US 8,173,970 B2
• Time in Patent Office: Days
• US Class Current: 250/359.100
• CPC Class Codes: G01V 5/0075 Passive interrogation for hand, feet or portals G01T1/167; for contaminated surface areas G01T1/169
• CPC Class Codes: G01V 5/0091 detecting special nuclear material [SNM], e.g. Uranium-235, Uranium-233 or Plutonium-239
• CPC Class Codes: G01V 5/26 Passive interrogation, i.e. by measuring radiation emitted by objects or goods
• CPC Class Codes: G01V 5/281 detecting special nuclear material [SNM], e.g. Uranium-235, Uranium-233 or Plutonium-239

Abstract

A method for detecting Special Nuclear Materials (SNM) or Radiological dispersion Devices (RDD), comprising: conveying an object along a predetermined path; imaging a distribution of radioactive sources associated with the object as it passes along said path; determining the presence and location of one or both of an RDD or SNM radioactive source within the object.

Claims

1. A method for detecting Special Nuclear Materials (SNM) or Radiological dispersion Devices (RDD), comprising:

conveying an object along a predetermined path;

imaging a distribution of radioactive sources associated with the object as it passes along said path;

determining the presence and location of one or both of an RDD or SNM radioactive source within the object.

2. A method according to claim 1 and further comprising:

determining at least one spectral characteristic of the radioactive source; and

classifying the source as benign or as a potentially illicit radioactive material, based on one or both of the determined presence and location and determined spectral characteristic.

3. A method according to claim 2 wherein determining the spectral characteristic comprises determining said characteristic responsive to the determination of location of the radioactive source.

4. A method according to claim 2 wherein:

determining the spectral characteristic comprises acquiring radiation using a spectrally sensitive detector that is separate from an imaging detector used to form the radionuclide distribution.

5. A method according to claim 4 wherein the imaging sensor is located at a first point along the path and wherein the spectrally sensitive detector is located further down the path.

6. A method according to claim 5 and including adjusting a field of view of the spectrally sensitive detector responsive to the determined location.

7. A method according to claim 6 wherein adjusting the field of view comprises adjusting a location of the spectrally sensitive sensor.

8. A method according to claim 6 wherein adjusting a field of view comprises adjusting an angle of one or more collimator septa of the spectrally sensitive detector.

9. A method according to claim 1 wherein imaging comprises neutron imaging.

10. A method according to claim 1 and including:

determining the presence of radionuclide quasi-point sources in the image, and

classifying the source as likely to be benign or as likely to be illicit nuclear material based on whether the source is a quasi-point source.

11. A method according to claim 2 and including:

determining the presence of quasi-point sources in the image,

wherein classifying the source as likely to be benign or as a likely to be illicit nuclear material comprises classifying based on whether the source is a quasi-point source.

12. A method according to claim 2 wherein at least a fraction of a population of particles used to determine the spectral characteristic is determined based on spatial distribution of radiation sources of said image.

13. A method according to claim 2 wherein an identification of radioactive threats and/or benign sources is based on data fusing of said imaging and said at least one spectral characteristic.

14. A method according to claim 2 and including identifying at least one isotope of said source based on the at least one spectral characteristic.

15. A method according to claim 1 wherein the object is a vehicle.

16. A method according to claim 1 wherein the object is an upright person.

17. A method according to claim 1 wherein the object is a package or parcel.

18. A method according to claim 2 and including acquiring an electronic visual image of the object.

19. A method according to claim 18 and including utilizing the visual image of the object to classify the source as potentially benign or potentially illicit.

20. A method according to claim 1 wherein imaging comprises:

acquiring a plurality of one dimensional images of a passing object; and

fusing the images into a two dimensional image.

21. A method according to claim 2 wherein classifying comprises separately determining the presence of a plurality of threat isotopes, utilizing different criteria for said determinations.

22. A method for detection of nuclear radiation comprising:

providing an image of a distribution of nuclear radiation from an object; and

classifying the distribution as belonging to a benign source or a weapons source.

23. A method according to claim 22 wherein the object is a person.

24. A method according to claim 22 wherein the object is a conveyence.

25. Apparatus for detecting Special Nuclear Materials (SNM) or Radiological dispersion Devices (RDD) from an object comprising:

at least one detector, operative and configured to detect radiation emanating from at least RDD and SNM associated with an object passing along a predetermined path and to form an image output based on the detected radiation;

a controller configured to receive the image output and to determine the presence and location of a radioactive source or sources within the object.

26. Apparatus according to claim 25 wherein the at least one same detector is also operative to generate spectral energy information on at least RDD and SNM radionuclide sources.

27. Apparatus according to claim 26 wherein the controller is operative and configured to receive the spectral energy information and determine whether the radioactive source is a benign or threat source based on the image data and on the spectral energy information.

28. Apparatus according to claim 25 wherein the at least one detector comprises:

at least one imaging detector that produces a radionuclide image; and

at least one spectral energy detector that determines spectral information from radiation at the determined location.

29. Apparatus according to claim 28 wherein the controller is operative to receive the spectral information and determine whether the radioactive source is a benign or threat source based on the image data and on the spectral information.

30. Apparatus according to claim 28, wherein the at least one imaging detector has a first field of view and wherein the at least one spectral detector has a second field of view and wherein the first and second fields of view are arranged such that an object can pass from the imaging detector to the spectral energy detectors as it passes along the predetermined path.

31. Apparatus according to claim 30 wherein the controller controls the second field of view such that the second field of view includes the detected source, wherein the second field of view is smaller than the first field of view.

32. Apparatus according to claim 31 wherein the spectral detector is movable and wherein the controller translates the spectral detector to include the detected source in the second field of view.

33. Apparatus according to claim 32 wherein the controller determines a height of the source and adjusts the height of the spectral detector responsive to the determined height.

34. Apparatus according to claim 33 wherein the controller determines a position of the source along the path and wherein the spectral detector is translated in a direction parallel to the path to keep the source in the second field of view as the source travels along the path.

35. Apparatus according to claim 34 and including a velocity detector that determines a velocity of the object and wherein the controller utilizes the velocity to keep the source in the second field of view as the source travels.

36. Apparatus according to claim 31 wherein the spectral detector comprises a collimator having septa that define the second field of view and wherein the controller controls an angle of the septa such that the second field of view includes the source as the object passes the spectral detector.

37. Apparatus according to claim 30 wherein the at least one imaging detector comprises an organic scintillator.

38. Apparatus according to claim 37 wherein the organic scintillator is a liquid scintillator.

39. Apparatus according to claim 25 wherein at one detector of the at least one detector is sensitive to neutrons and wherein the image is an image of a neutron source.

40. A liquid scintillator detector comprising:

a vessel filled with liquid scintillator material;

a front face that is at least partially transparent to radiation detectable by the liquid scintillator material;

at least one partition that separates the vessel into sections; and

a plurality of light detectors arranged to detect light produced in the liquid scintillator,

wherein each section is situated within the vessel such that one portion of its periphery is formed by a portion of its front face.

41. A liquid scintillator detector according to claim 40 wherein the partition reflects a substantial portion of the light that is incident on it into the portion.

42. A liquid scintillator detector according to claim 41 wherein the partition is substantially transparent to radiation detected by the liquid scintillator material.

43. A liquid scintillator detector according to claim 42 and including a controller that receives signals representing scintillations detected by each of the light detectors and determines the energy of an event responsive to signals generated by a plurality of the light detectors at a substantially same time.

44. A liquid scintillator according to claim 43 wherein the controller is configured to determine the incident particle energy by adding the signals from at least two adjacent sectors.

45. A liquid scintillator detector according to claim 40 that is operative to detect and image gamma rays.

46. A liquid scintillator detector according to claim 45 wherein the scintillator detector is also operative to detect neutrons.

47. A liquid scintillator detector according to claim 46 wherein the scintillator detector is also operative to image neutrons.

48. A liquid scintillator detector according to claim 40 wherein the scintillator detector is also operative to detect neutrons.

49. A liquid scintillator detector according to claim 48 wherein the scintillator detector is also operative to image neutrons.

50. An imaging detector that is operative to detect and image a source or sources of neutrons.

51. An imaging detector according to claim 50 that is also operative to image and detects gamma rays.

52. A system for detecting nuclear/radiological treats, comprising:

a nuclear radiation detector configured for detecting RDD and SNM and having an entrance surface, the detector being mounted so that its entrance surface is substantially perpendicular to a ground surface; and

a collimator which defines a direction of view of the detector, the collimator being configured to reduce the effect of radiation emanating from the ground.

53. A system according to claim 52, wherein the collimator comprises absorbing septa and wherein at least some of the septa defining a vertical direction of view are inclined upward as compared to the ground surface.

54. A system according to claim 52 wherein the detector is an imaging detector.

55. A method for detecting threats, comprising:

generating first image data based on radionuclide radiation detected by a detector in the absence of any threats;

generating a second image data based on nuclear radiation detected by the detector in the presence of a possible threat; and

adjusting the at least one second image data based on the at least one first image.

56. A method according to claim 55 wherein said threats include one or more of RDD and SNM.

57. A method according to claim 55 wherein the first and second images are images of a neutron distribution.

58. A method according to claim 55 wherein the first and second images represent a spatial distribution of gamma particles.

59. A method according to claim 55 and including:

determining the presence of a threat responsive to the adjusted second image.

60. Apparatus for radioactive emission tomographic imaging of a moving conveyance, comprising:

a plurality of nuclear imaging detectors placed around the axis of a path suitable for passage of a moving conveyance, the detectors being operative to detect and image radiation from at least some RDD and SNM sources; and

a controller that receives signals from the nuclear imaging detectors and forms a tomographic image of sources of radiation associated with the conveyance and its cargo.

61. Apparatus according to claim 60 wherein the controller receives a plurality of sets of signals from the detectors as a vehicle passes along the path and derives a tomographic distribution of radionuclide sources associated with the conveyance.

62. A method for determining a nuclear threat associated with a conveyence, comprising:

(a) detecting nuclear emissions from the conveyance at a first detection station;

(b) determining conveyances that do not pose a threat according to a first criterion responsive to the emissions detected at the first detection station;

(c) directing conveyances that contain potential threats according to the first criteria to a second detection station and releasing conveyances that do not meet the first criterion;

(d) detecting nuclear emissions from the conveyance at the second detection station;

(e) determining conveyances that do not pose a threat according to a second criterion responsive to the emissions detected at the second detection station;

(f) directing vehicles that contain potential threats according to the second criterion to a third station for further inspection; and

(g) releasing conveyances that do not contain potential threats according to any of the criteria, without further testing.

63. A method according to claim 62 and including:

repeating at least (d) and (e) at least once for respective additional detection stations prior to (f).