Neutron and gamma ray monitor

• US 20050023479A1
• Filed: 06/04/2004
• Published: 02/03/2005
• Est. Priority Date: 06/05/2003
• Status: Abandoned Application

• Current Assignee: Thermo Niton Analyzers LLC (Thermo Fisher Scientific Incorporated)
• Original Assignee: Thermo Niton Analyzers LLC (Thermo Fisher Scientific Incorporated)
• Inventors: Grodzins, Lee
• Application Number:
  US10/861,332
• Publication Number:
  US 20050023479A1
• Time in Patent Office: Days
• US Class Current: 250/390.110
• CPC Class Codes: G01T 3/06 with scintillation detectors

Abstract

An apparatus for selective radiation detection includes a neutron detector that facilitates detection of neutron emitters, e.g. plutonium, and the like; a gamma ray detector that facilitates detection of gamma ray sources, e.g., uranium, and the like; and/or an X-ray analyzer that facilitates detection of materials that can shield radioactive sources, e.g., lead, and the like.

Claims

1. An apparatus for selective radiation detection, comprising:

a neutron scintillator;

an optical detector; and

a light guide that couples the neutron scintillator to the optical detector, wherein the light guide is solid or liquid.

2. The apparatus of claim 1, wherein the apparatus is adapted to be handheld.

3. The apparatus of claim 1, wherein the neutron scintillator selectively responds to thermal neutrons over gamma rays by a factor of at least about 10,000:

1.

4. The apparatus of claim 1, wherein the apparatus selectively responds to thermal neutrons over gamma rays by a factor of at least about 1,000,000:

1.

5. The apparatus of claim 1, further comprising a plurality of light guides.

6. The apparatus of claim 1, further comprising a plurality of neutron scintillators.

7. The apparatus of claim 1, wherein the neutron scintillator responds to fast neutrons.

8. The apparatus of claim 1, wherein the neutron scintillator responds to thermal neutrons.

9. The apparatus of claim 8, wherein the neutron scintillator comprises a thermal neutron capturing isotope coupled to a scintillation component that scintillates upon exposure of the capturing isotope to thermal neutrons.

10. The apparatus of claim 9, wherein the capturing isotope is selected from ⁶Li, ¹⁰B, ¹¹³Cd, and ¹⁵⁷Gd.

11. The apparatus of claim 9, wherein the scintillation component is ZnS.

12. The apparatus of claim 9, wherein the neutron scintillator comprises ⁶LiF and ZnS.

13. The apparatus of claim 7, wherein the light guide has a refractive index from about 1.4 to about 2.4.

14. The apparatus of claim 13, wherein the light guide comprises a hydrogenous material that thermalizes fast neutrons.

15. The apparatus of claim 13, wherein the light guide includes at least one material selected from water, organic solvents, mineral oil, and organic polymers.

16. The apparatus of claim 13, wherein the light guide is polymethyl methacrylate.

17. The apparatus of claim 14, wherein the hydrogen nuclei in the light guide are enriched in the ²H isotope of hydrogen.

18. The apparatus of claim 1, wherein the apparatus is covered at least in part by a material that thermalizes fast neutrons.

19. The apparatus of claim 18, wherein the apparatus is covered at least in part by a material selected from water, organic solvents, mineral oil, and organic polymers.

20. The apparatus of claim 19, wherein the hydrogen nuclei in the light guide are enriched in the ²H isotope of hydrogen.

21. The apparatus of claim 1, wherein the apparatus is covered at least in part by high density polyethylene.

22. The apparatus of claim 8, further comprising a controller coupled to the optical detector.

23. The apparatus of claim 22, further comprising a display coupled to the controller to display radiation detection results.

24. The apparatus of claim 22, wherein the light guide includes a fast neutron scintillator, the controller detecting temporal characteristics of scintillation to distinguish scintillation corresponding to fast neutrons from scintillation corresponding to thermal neutrons.

25. The apparatus of claim 22, further including a plurality of neutron scintillators and a plurality of light guides, wherein the major surfaces of the neutron scintillators are substantially aligned with the optical axis of the optical detector.

26. The apparatus of claim 25, wherein the light guides are planar sheets of polymethyl methacrylate.

27. The apparatus of claim 25, wherein the controller independently detects a scintillation signal at the optical detector from each of at least two light guides, and correlates the relative strength of the scintillation signals with the direction of a neutron source incident on the apparatus.

28. The apparatus of claim 8, further comprising a gamma ray scintillator coupled to the optical detector.

29. The apparatus of claim 28, wherein the gamma ray scintillator has a refractive index from about 1.4 to about 2.4.

30. The apparatus of claim 28, wherein the gamma ray scintillator has a transparency of at least about 95% per meter for light from about 300 nm to about 600 nm.

31. The apparatus of claim 28, wherein the gamma ray scintillator comprises a material selected from NaI(Tl), CsI(Tl), BGO, BaF₂, LSO, and CdWO₄.

32. The apparatus of claim 28, wherein the gamma ray scintillator is BaF₂.

33. The apparatus of claim 28, further comprising a controller that is coupled to the optical detector to selectively detect neutrons and gamma rays.

34. The apparatus of claim 33, wherein the controller selectively detects neutrons and gamma rays by the temporal characteristics of their scintillation signals.

35. The apparatus of claim 28, further comprising an X-ray fluorescence analyzer.

36. The apparatus of claim 35, wherein the X-ray fluorescence analyzer is adapted for independent operation by umbilical cord or wireless communication.

37. The apparatus of claim 35, further comprising a controller that:

is coupled to the optical detector to selectively detect neutrons and gamma rays; and

is coupled to the X-ray fluorescence analyzer to detect X-ray fluorescence.

38. The apparatus of claim 37, wherein the controller is coupled to the X-ray fluorescence analyzer to irradiate a target with X-rays and selectively detect X-ray fluorescence from the target.

39. The apparatus of claim 1, further comprising an X-ray fluorescence analyzer.

40. The apparatus of claim 39, wherein the X-ray fluorescence analyzer is adapted for independent operation by umbilical cord or wireless communication.

41. The apparatus of claim 39, further comprising a controller that is coupled to the optical detector to selectively detect neutrons.

42. The apparatus of claim 41, wherein the controller is coupled to the X-ray fluorescence analyzer to irradiate a target with X-rays and selectively detect X-ray fluorescence from the target.

43. The apparatus of claim 8, further comprising a solid state gamma ray detector.

59. The apparatus of claim 1, further comprising:

a gamma ray scintillator coupled to the optical detector; and

an X-ray fluorescence analyzer.

60. The apparatus of claim 59, wherein the gamma ray scintillator and neutron scintillator coupled to the optical detector are adapted for operation independent from the X-ray fluorescence analyzer by umbilical cord or wireless communication.

61. The apparatus of claim 59, further comprising a controller that:

is coupled to the optical detector to selectively detect fast neutrons, slow neutrons, and gamma rays by the temporal characteristics of their scintillation signals;

is coupled to the X-ray fluorescence analyzer to irradiate a target with X-rays and selectively detect X-ray fluorescence from the target; and

is coupled to a display for displaying radiation detection results.

62. The apparatus of claim 61, wherein the apparatus is adapted to be handheld.

44. An apparatus for selective radiation detection, comprising:

an X-ray fluorescence analyzer; and

a gamma ray scintillator coupled to at least one optical detector.

45. The apparatus of claim 44, wherein the X-ray fluorescence analyzer is adapted for independent operation by umbilical cord or wireless communication.

46. The apparatus of claim 44, wherein the gamma ray scintillator is BaF₂.

47. The apparatus of claim 46, further comprising a controller that:

is coupled to the optical detector to selectively detect gamma rays; and

is coupled to the X-ray fluorescence analyzer to irradiate a target with X-rays and selectively detect X-ray fluorescence from the target.

48. The apparatus of claim 46, wherein the apparatus is adapted to be handheld.

49. An apparatus for selective radiation detection, comprising:

an X-ray fluorescence analyzer; and

a neutron scintillator coupled to an optical detector.

50. The apparatus of claim 49, wherein the X-ray fluorescence analyzer is adapted for independent operation by umbilical cord or wireless communication.

51. The apparatus of claim 49, further comprising a controller that:

is coupled to the optical detector to selectively detect fast and thermal neutrons by scintillation as a function of time;

is coupled to the X-ray fluorescence analyzer to irradiate a target with X-rays and selectively detect X-ray fluorescence from the target; and

is coupled to a display for displaying radiation detection results.

52. The apparatus of claim 50, wherein the apparatus is adapted to be handheld.

53. An apparatus for selective radiation detection, comprising a gamma ray detector and a neutron scintillator coupled to an optical detector.

54. The apparatus of claim 53, wherein the gamma ray detector is a gamma scintillation detector coupled to the optical detector.

55. The apparatus of claim 54, further comprising a controller that is coupled to the optical detector to selectively detect neutrons and gamma rays by their temporal characteristics.

56. The apparatus of claim 54, wherein the controller selectively detects fast neutrons, thermal neutrons, and gamma rays by their temporal characteristics.

57. The apparatus of claim 56, further comprising a controller that:

is coupled to an X-ray fluorescence analyzer to irradiate a target with X-rays and selectively detect X-ray fluorescence from the target; and

is coupled to a display for displaying radiation detection results.

58. The apparatus of claim 57, wherein the apparatus is adapted to be handheld.

63. An apparatus for selective radiation detection, comprising:

a neutron scintillator that selectively responds to thermal neutrons over gamma rays by a factor of at least about 1,000,000;

1;

an optical detector; and

a light guide that couples the neutron scintillator to the optical detector.

64. A handheld apparatus for selective radiation detection, comprising:

a neutron scintillator material that selectively responds to thermal neutrons over gamma rays by a factor of at least about 1,000,000;

1;

a gamma ray scintillator;

an optical detector coupled to the neutron scintillator and the gamma ray scintillator;

a plurality of light guides in the form of planar sheets, the sheets being interleaved with the neutron scintillator material to couple neutron scintillation to the optical detector;

an X-ray fluorescence analyzer; and

a controller coupled to the optical detector and the X-ray analyzer.

65. A method for selectively detecting radiation, comprising the steps of:

exposing a neutron scintillator to a source of neutron radiation;

directing scintillation from the neutron scintillator to an optical detector through a light guide;

selectively detecting neutrons compared to gamma rays by a factor of at least about 10,000;

1.

66. The method of claim 65, wherein the neutrons are detected in a handheld apparatus.

67. The method of claim 65, further including selectively detecting neutrons compared to gamma rays by a factor of at least about 1,000,000:

1.

68. The method of claim 65, further comprising directing the scintillation to the optical detector with a plurality of light guides.

69. The method of claim 65, further comprising exposing a plurality of neutron scintillators to the source of neutron radiation.

70. The method of claim 65, further comprising detecting fast neutrons.

71. The method of claim 65, further comprising detecting thermal neutrons.

72. The method of claim 65, further comprising thermalizing fast neutrons with the light guide, wherein the light guide includes at least one material selected from water, organic solvents, mineral oil, and organic polymers.

73. The method of claim 71, wherein the light guide is polymethyl methacrylate.

74. The method of claim 72, wherein the hydrogen nuclei in the light guide are enriched in the ²H isotope of hydrogen.

75. The method of claim 65, further comprising thermalizing fast neutrons before the neutrons contact the neutron scintillator or the light guide.

76. The method of claim 65, further comprising capturing thermal neutrons with a capturing isotope selected from ⁶Li, ¹⁰B, ¹¹³Cd, and ¹⁵⁷Gd.

77. The method of claim 76, further comprising causing scintillation by contacting the reaction products of the thermal neutrons and the capturing isotope with ZnS.

78. The method of claim 65, further comprising automatically selectively detecting radiation.

79. The method of claim 78, further comprising automatically displaying radiation detection results.

80. The method of claim 78, further comprising automatically distinguishing scintillation corresponding to fast neutrons from scintillation corresponding to thermal neutrons by detecting temporal characteristics of scintillation.

81. The method of claim 78, further comprising automatically determining the direction of a neutron source with respect to the optical detector by comparing scintillation directed from at least two light guides to the optical detector.

82. The method of claim 65, further comprising contacting a gamma ray scintillator selected from NaI(Tl), CsI(Tl), BGO, BaF₂, LSO, and CdWO₄ with gamma rays, directing gamma ray scintillation to the optical detector, and detecting the gamma ray scintillation.

83. The method of claim 82, further comprising automatically selectively detecting neutron and gamma ray scintillation at the optical detector.

84. The method of claim 83, further comprising selectively detecting gamma rays and neutrons by comparing the temporal characteristics of their scintillation signals.

85. The method of claim 84, further comprising automatically irradiating a target with X-rays and selectively detecting X-ray fluorescence from the target for evidence of a radioactive shielding material that includes a high atomic weight element.

86. The method of claim 85, further comprising conducting the X-ray fluorescence analysis independently by umbilical cord or wireless communication.

87. A method for selectively detecting radiation, comprising:

analyzing X-ray fluorescence from a target; and

detecting gamma rays by contacting a gamma ray scintillator with gamma rays and detecting scintillation.

88. The method of claim 87, further comprising automatically irradiating a target with X-rays and selectively detecting X-ray fluorescence from the target.

89. The method of claim 87, further comprising automatically displaying the radiation detection results.

90. The method of claim 87, further comprising conducting the X-ray fluorescence analysis independently by umbilical cord or wireless communication.

91. A method for selectively detecting radiation, comprising:

analyzing X-ray fluorescence from a target; and

detecting neutrons by contacting a neutron scintillator with neutrons and detecting scintillation.

92. The method of claim 91, further comprising automatically irradiating a target with X-rays and selectively detecting X-ray fluorescence from the target.

93. The method of claim 91, further comprising automatically displaying the radiation detection results.

94. The method of claim 91, further comprising automatically detecting scintillation in the neutron scintillator from neutrons, neutrons being selectively detected in the neutron scintillator compared to gamma rays by a ratio of at least about 1,000,000:

1.

95. The method of claim 91, further comprising conducting the neutron detection in a separate module that communicates with the controller by umbilical cord or wireless communication.

96. A method for selectively detecting radiation, comprising:

contacting a neutron scintillator with neutrons;

contacting a gamma ray scintillator with gamma rays; and

selectively detecting scintillation from the neutrons and the gamma rays.

97. The method of claim 96, further comprising automatically selectively detecting neutrons and gamma rays by comparing the temporal characteristics of their scintillation.

98. The method of claim 96, further comprising automatically selectively detecting fast neutrons, thermal neutrons, and gamma rays by comparing the temporal characteristics of their scintillation.

99. The method of claim 96, further comprising automatically detecting scintillation in the neutron scintillator from neutrons, neutrons being selectively detected in the neutron scintillator compared to gamma rays by a ratio of at least about 1,000,000:

1.

100. A method for selective detection of radioactive weapons of mass destruction or shields thereof, comprising:

exposing a neutron scintillator to a suspected neutron source, and analyzing for scintillation in the neutron scintillator from neutrons, neutrons being selectively detected in the neutron scintillator compared to gamma rays by a ratio of at least about 1,000,000;

1;

exposing a gamma ray scintillator to a suspected gamma ray source and analyzing for scintillation in the gamma ray scintillator from gamma rays; and

irradiating a target with X-rays and selectively analyzing X-ray fluorescence from the target for evidence of high atomic weight shielding material.

101. Means for selectively detecting radiation, comprising:

means for exposing a neutron scintillator to a source of neutron radiation;

means for directing scintillation from the neutron scintillator to an optical detector; and

means for selectively detecting neutrons compared to gamma rays by a factor of at least about 10,000;

1.

102. Means for selectively detecting radiation, comprising:

means for analyzing X-ray fluorescence from a target; and

means for detecting gamma rays.

103. Means for selectively detecting radiation, comprising:

means for analyzing X-ray fluorescence from a target; and

means for detecting neutrons.

104. Means for selectively detecting radiation, comprising:

means for detecting neutrons; and

means for detecting gamma rays.