Nuclear Threat Detection

• US 20060289775A1
• Filed: 08/08/2006
• Published: 12/28/2006
• Est. Priority Date: 02/04/2005
• Status: Active Grant

• Current Assignee: Dan Inbar
• Original Assignee: Dan Inbar
• Inventors: Inbar, Dan
• Granted Patent: US 7,847,260 B2
• Time in Patent Office: Days
• US Class Current: 250/370.110
• CPC Class Codes: G01T 1/167 Measuring radioactive content of objects, e.g. contamination whole body counters G01T1/163
• CPC Class Codes: G01T 1/20 with scintillation detectors
• 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 detector for detecting radiation, the detector comprising: a plurality of elongate scintillator segments arranged in a side by side array; and at least one pair of light sensors optically coupled to ends of each of the elongate scintillator such that they receive light from scintillations produced in the scintillator and generate electrical signals responsive thereto.

Claims

1. A detector for detecting nuclear radiation threats, the detector comprising:

a plurality of elongate scintillator segments arranged in a side by side array; and

at least one pair of light sensors optically coupled to ends of each of the elongate scintillator segments such that they receive light from scintillations produced in the scintillator segments and generate electrical signals responsive thereto.

2. A detector according to claim 1 wherein the segments are separated by partitions that are substantially transparent to gamma radiation and are reflectors for light.

3. A detector according to claim 2 wherein the segments are contiguous, separated only by said partitions.

4. A detector according to claim 2 wherein the scintillator segments are at least partly non-contiguous.

5. A detector according to claim 1 wherein the segments have a rectangular cross-section perpendicular to the elongate direction.

6. A detector according to claim 1 wherein the segments have a circular cross-section perpendicular to the elongate direction.

7. A detector according to claim 1 wherein the scintillator segments comprise an organic scintillator.

8. A detector according to claim 7 wherein the organic scintillator is a liquid organic scintillator.

9. A detector according to claim 8 wherein the light sensors have input face plates and wherein the faceplates are in direct contact with the liquid organic scintillator.

10. A detector according to claim 1 and also comprising:

a controller that receives the electrical signals and generates an image of the sources of radiation that cause the scintillations.

11. A detector according to claim 1, wherein the scintillator produces scintillations responsive to incoming neutrons, and further comprising:

a controller that receives the electrical signals and determines the positions of the incident neutrons on the detector.

12. A detector according to claim 1, wherein the scintillator produces scintillations responsive to incoming neutrons, and further comprising:

a controller that receives the electrical signals and generates an image of the sources of neutron radiation that cause the scintillations.

13. A detector according to claim 7 and comprising:

a controller that receives the electrical signals, and produces an energy value, the energy value being responsive to the electrical signals, wherein the energy value is corrected based on the location of the scintillation within the scintillator segment.

14. A detector according to claim 7 and comprising:

a plurality of collimators on a front face of the organic scintillator that block radiation that would be detected by the said detector from parts of the radiation field.

15. A detector according to claim 14 wherein the plurality of collimators restrict block radiation over only a portion of the front face.

16. A detector according to claim 7 wherein the plurality of elongate scintillators form a detector having a front face having a total area greater than 1 meter by 1 meter.

17. A detector according to claim 8 for detecting nuclear threats that generate one of both of neutrons and gammas, wherein the light sensors receive light of scintillations in the liquid organic scintillator caused by gammas and neutrons;

and

a controller that receives the electrical and generates both a count of the incident neutrons and a spectroscopic energy analysis of the gammas.

18. A detector according to claim 1 wherein the plurality of elongate scintillators form a detector having a front face and a back face and wherein the scintillators produce scintillations in response to radiation that enters the detector via the front face and the back, and comprising:

a controller that receives the electrical signals, and discriminates between the radiation entering the front and rear faces.

19. A detector according to claim 1 wherein the plurality of elongate scintillators form a detector having a front face, and comprising:

a controller that receives the electrical signals, generates a gross direction of incidence of the incident radiation from said signals, without considering the presence or absence of collimation and rejects at least some incident radiation particles that do not come from a direction at which a suspected source is situated.

20. A detector according to claim 7 wherein the plurality of elongate scintillators form a detector having a front face, wherein the front face is not flat, and wherein alternating portions of the front face extend further front than other portions.

21. A detector according to claim 1 wherein a plurality of said arrays are stacked in a direction perpendicular to the direction of said array to form a three dimensional array of said elongate scintillator segments.

22. A detector according to claim 1 wherein said plurality of scintillator segments comprise a plurality of segments formed of a series of light reflecting low atomic weight partitions placed in a vessel filled with liquid scintillator material, such that the partitions form the individual elongate segments.

23. A detector according to claim 1 and including

a controller that receives the electrical signals and generates a timestamp reflecting the time that the light arrives at the light sensors.

24. A detector according to claim 23 wherein the signals are proportional to the total energy deposited in the detector by the incident particle.

25. A detector according to claim 24 wherein the light sensors are photomultiplier tubes (PMTs).

26. A detector according to claim 25 wherein the controller corrects the timestamps for systematic variations of individual PMT channel delays.

27. A detector according to claim 24 wherein the controller corrects the signals for loci dependent light collection efficiency systematic variations.

28. A detector according to claim 21 wherein the thickness of the stacks is deep enough to allow full energy deposition in the detector for more than 60% of 2.6 MeV gamma particles incident at the center of the front face.

29. At least one detector according to claim 1 utilized in a screening portal having a lane, wherein a detector is placed at one side of the lane.

30. A pair of detectors according to claim 1 utilized in a screening portal having a lane, wherein a detector is placed at each side of the lane.

31. A plurality of detectors according to claim 1 wherein the detectors are spaced to form a plurality of vehicle lanes and where a single detector is utilized to detect radiation from adjoining lanes.

32. At least one detector according to claim 1 utilized in a screening portal lane wherein the at least one detector surrounds at least 50% of the lane.

33. At least one detector according to claim 32 wherein the at least one detector surrounds at least 75% of the lane.

34. At least one detector according to claim 32 wherein the at least one detector completely surrounds the lane.

35. A detector according to claim 1 mounted in a vehicle to provide a portable nuclear threat screening device.

36. A detector according to claim 1 and including a controller that identifies a plurality of scintillations as emanating from a single incident particle based on a time window within which they fall and their spatial proximity within the detector.

37. A detector according to claim 16 wherein the detector function is disguised or hidden so that it detects threats in a covert manner.

38. A detector according to claim 16 including:

a source of activating radiation that stimulates emission of radiation from SNM and radiation shielding, wherein the scintillator segments are positioned to receive said stimulated emission.

39. A plurality of detectors according to claim 1;

and

a controller that receives the electrical signals and generates a tomographic image of sources of the radiation.

40. A detector according to claim 1 wherein the scintillator is a PPO based liquid scintillator.

48. An SNM detection system utilizing a detector according to claim 1, effective to screen vehicles moving at a velocity greater than 40 MPH.

49. A method of utilizing a detector according to claim 1 in an SNM detection system, comprising screening a suspected item by placing it before at least one detector while the item is stationary to increase the number of radiation events captured by the detector.

41. A system for detection of radiation signatures of SNM and RDD devices and materials from a screened object, comprising:

at least one scintillator which produces scintillations when impinged by gamma and neutron radiation;

a plurality of optical sensors optically coupled to the at least one scintillator such that they receive light from scintillations produced in the scintillator and generate electrical signals responsive thereto; and

a controller that receives the signals and performs a multi-signature detection of threats including a plurality of the following threat detection inputs or characterizations;

(a) gamma spectroscopy isotope signature;

(b) gamma imaging morphologic signature;

(c) neutron counting;

(d) neutron imaging;

(e) cascaded isotopes doublets or triplets signature;

(f) SNM spontaneous fission signature;

(g) comparison with optical images of the screened object; and

(h) gross directionality of incidence of radiation as compared to the direction of the screened object.

42. A system according to claim 41 wherein the at least one scintillator comprises a segmented organic scintillator comprising at least four elongate segments.

43. A system according to claim 42 where the scintillator comprises a liquid scintillator.

44. A system according to claim 41 wherein the plurality comprises at least three of said threat detection inputs or characterizations.

45. A system according to claim 41 wherein the plurality comprises at least four of said threat detection processes.

46. A detector according to claim 41 wherein the plurality comprises at least five of said threat detection inputs or characterizations.

47. A detector for detecting incident neutrons, comprising;

at least one scintillator that produces scintillations responsive to incoming neutrons produced by WGP;

a plurality of photo-detectors that receive light of the scintillations and produces electrical signals responsive thereto; and

a controller that receives the light and generates an image of the sources of neutron radiation that cause the scintillations.