Explosive detection system

• US 5,006,299 A
• Filed: 03/09/1989
• Issued: 04/09/1991
• Est. Priority Date: 05/26/1987
• Status: Expired due to Term

• Current Assignee: Rapiscan Laboratories Incorporated (OSI Systems Incorporated)
• Original Assignee: Science Applications International Corporation
• Inventors: Gozani, Tsahi, Shea, Patrick M.
• Primary Examiner(s): Behrend, Harvey E.
• Application Number:
  US07/321,511
• Time in Patent Office: 761 Days
• Field of Search: 376/159, 376/257
• US Class Current: 376/159
• CPC Class Codes: G01T 3/06 with scintillation detectors
• CPC Class Codes: G01V 5/226 using tomography
• CPC Class Codes: G01V 5/234 Measuring induced radiation, e.g. thermal neutron activation analysis

Abstract

A system for detecting the presence of explosives contained in an object under observation, including a cavity structure for receiving the object and a radiation source for producing thermal neutrons directed to the object under observation. Gamma rays are produced to represent the presence of explosives and as an example the concentration of nitrogen contained in the object. Inorganic scintillators are located within the cavity structure to detect the gamma rays and produce an output signal representative of the presence and concentration of the nitrogen and/or other elements contained in the object. The inorganic scintillators are formed as a ring around the cavity structure to detect the nitrogen and/or other elements within at least one particular plane passing through the object. The object under observation is moved through the cavity structure to detect the nitrogen in successive planes to build up a three dimensional profile of explosives concentration.

Claims

1. A system for detecting the presence of explosive in an object under observation by detection of a particular element, and the concentration of such particular, element, at the different positions in the object, including,

a cavity structure for receiving the object under observation,

means stationary in the cavity structure for providing thermal neutrons to the object under observation for interaction with the object under observation to obtain the production from the object of gamma rays representative of the presence and concentration of the particular element in the object,

means for moving the object through the cavity structure,

a plurality of inorganic detectors disposed in the cavity structure and operative independently of one another and positioned relative to the thermal neutron means and the object for detecting the gamma rays to produce output signals indicative at each instant of such gamma rays,

the thermal neutron means and the inorganic detectors being disposed in a common planar relationship enclosing the object to obtain the detection by the inorganic detectors at each instant of the gamma rays in such common plane, the common planar relationship being transverse to the direction of movement of the object through the cavity structure, the inorganic detectors in the plurality being operative independently of one another, and

means responsive to the output signals from the inorganic detectors at progressive instants of time in the common planar relationship during the movement of the object through the cavity structure for processing such signals to indicate the presence, and the concentration of the particular element, at the different positions in the object on a three-dimensional basis.

2. The system of claim 1, wherein the moving means includes a conveyor passing through the cavity structure and supporting the object under observation to move the object through the cavity structure and provide for detection of the presence, and the concentration on a three-dimensional basis, of the particular element at the different positions in successive planes of the object, the successive planes being substantially parallel to the common planar relationship.

3. The system of claim 2 wherein the object is a container and wherein the thermal neutron means are disposed relative to the container in the common planar relationship to direct the thermal neutrons into the container and wherein the inorganic detectors are disposed relative to the container in the common planar relationship for receiving the gamma rays emanating from the container, the common planar relationship being substantially perpendicular to the direction of movement of the object through the cavity structure.

4. The system of claim 1 wherein the inorganic detectors are formed from at least one of the following materials:

Sodium Iodide (NaI), Cesium Iodide (CsI), Bismuth Germanate (Bi₄ Ge₃ O₁₂), Barium Floride (BaF₂), and solid-state detectors including Lithium-drifted Germanium (Ge(Li)), High Purity Germanium (HPGe), and Mercuric Iodide (HgI₂).

5. The system of claim 3 wherein the inorganic detectors are formed from Sodium Iodide (NaI).

6. The system of claim 1 wherein the inorganic detectors, operative independently of one another, are disposed as a plurality of individual detectors in a C-ring configuration, open at one end, in the common plane around the cavity structure and the thermal neutron means are disposed at the open end of the C-ring configuration in the common planar relationship to obtain the detection by the inorganic detectors of the presence of the particular element, and the concentration of the particular element at different positions, within the common planar relationship to produce output signals representing the presence of the particular element in the object in such common plane and wherein

the processing means process the signals produced at successive instants by the inorganic detectors in such common planar relationship during the movement of the container through the cavity structure to indicate the presence, and the concentration at each position in the object on a three-dimensional basis, of the particular element in the object.

7. The system of claim 6, including, the inorganic detectors being positioned in the common planar relationship to detect the particular element within a plurality of successive planes through the object in accordance with the movement of the object past the common planar relationship to obtain a three dimensional representation by the processing means of the presence, and the concentration at each position in the object in the three dimensional representation, of the particular element in the object.

8. The system of claim 7 wherein the processing means include computer means responsive to the output signals from the inorganic detector means for producing an alarm condition in response to particular patterns of three dimensional concentrations of the particular element in the object.

9. The system of claim 6 wherein the plurality of individual detectors are disposed in the common planar relationship in a C-ring configuration, open at one end, with the thermal neutron means disposed in the common planar relationship in the open portion of the C-ring configuration.

10. The system of claim 6 wherein the plurality of individual detectors are formed in a pair of common planar relationships into a pair of C-ring configurations in which each C-ring configuration has an open end opposite the open end in the other C-ring configuration and in which the pair of C-ring configurations are spaced from each other in the direction of movement of the object and wherein the thermal neutron means are respectively disposed in the common planar relationships in the open ends of the C-ring configurations.

11. The system of claim 10 wherein the inorganic detectors are disposed relative to the moving object and the thermal neutron means to detect the particular element in a plurality of successive spaced planes through the object in accordance with the movement of the object through the cavity structure to obtain a three dimensional profile by the processing means of the presence, and the concentration at different positions on a three-dimensional basis, of the particular element in the object.

12. The system of claim 11 wherein the detectors in each of the C-ring configurations are disposed in oppositely positioned columns from the positioning of the detectors in the other C-ring configuration and each of the columns has parallel sets of the inorganic detectors.

24. The system of claim 10 wherein

side structures and top and bottom structures are disposed in the cavity structure and wherein the inorganic detectors in one of the C-ring configurations are disposed in three of the side and top and bottom structures in the cavity structure and wherein the inorganic detectors in the other C-ring configuration are disposed in three of the the top and bottom and side structures in the cavity structure and wherein the fourth one of the top and bottom and side structures in one of the open C-ring configurations is opposite the fourth one of the top and bottom and side structures in the other C-ring configuration and wherein the open C-ring configurations are substantially parallel to each other and substantially perpendicular to the direction of movement of the object through the cavity structure.

25. The system of claim 12 wherein

side structures and top and bottom structures are disposed in the cavity structure and wherein the inorganic detectors in one of the C-ring configurations are disposed in three of the top and bottom and side structures in the cavity structure and wherein the inorganic detectors in the other C-ring configuration are disposed in three of the top and bottom and side structures in the cavity structure and wherein the fourth one of the top and bottom and side structures in one of the C-ring configurations is opposite the fourth one of the top and bottom and side structures in the other C-ring configuration and wherein the open C-shaped configurations are substantially parallel to each other and substantially perpendicular to the direction of movement of the object through the cavity structure.

39. The system of claim 6 wherein the C-ring configuration is defined by three abutting sides and wherein different groups of the individual detectors in the plurality are disposed in the three planar sides and wherein the individual detectors in each group are operative independently of one another and independently of the detectors in the other groups.

40. The system of claim 6 wherein each of the C-ring configurations is defined by three abutting sides and wherein different groups of the individual detectors in the plurality are disposed in the three planar sides and wherein the individual detectors in each group are operative independently of one another and independently of the other groups.

43. The system of claim 24 wherein an individual group of detectors is disposed in each of the structures defining the positions of each of the C-ring configurations and wherein the individual detectors in each group are operative independently of one another and independently of the detectors in the other groups.

44. The system of claim 25 wherein an individual group of detectors is disposed in each of the structures defining the positions of each of the C-ring configurations and wherein the detectors in each group are operative independently of one another and independently of the detectors in the other groups.

13. A detection system for producing a three-dimensional profile of the concentration of a particular element at the different positions in an object, including

a cavity structure for receiving the particular object within the cavity structure, the cavity structure being defined by top and bottom walls and a pair of side walls,

stationary means for producing thermal neutrons within the cavity structure to interact with the object in forming gamma rays of a particular energy,

a plurality of scintillator detectors disposed within the cavity structure in a common plane with the thermal neutron means and operative independently of one another to detect the gamma rays from the object of the particular energy,

the plurality of detectors being disposed in an open C-ring configuration around the object to detect the concentration of the particularly element in the object in the common plane passing through the object and the thermal neutron means and the detectors during the movement of the object through the cavity structure, each detector producing output signals representative of the passage of the gamma rays from the object of the particular energy, the detectors being disposed adjacent the side walls and one of the top and bottom walls of the cavity structure,

means for moving the object through the cavity structure, and

means for processing the signals from the detectors to provide an indication of the concentration on a threedimensional basis of the particular element at the different positions in the object.

14. The system of claim 13 wherein the moving means includes a conveyer means passing through the cavity structure and supporting the object to move through the cavity structure and to provide for the detection of the presence and concentration of the particular element in successive planes of the object parallel to the common plane and to provide a three dimensional representation of the concentration of the particular element in the object at the different positions in the object.

15. The system of claim 14 wherein the object is a container and wherein means are provided for processing the output signals from the detectors to provide the three dimensional representation profile of the concentration of the particular element in the object at the different positions in the object and wherein the common plane is substantially perpendicular to the direction of movement of the object through the cavity structure.

16. The system of claim 14 additionally including computer means responsive to the output signals from the detectors for producing an alarm condition in response to particular three dimensional representations of the concentration of the particular element in the object at the different positions in the object and wherein the common plane is substantially perpendicular to the direction of movement of the object through the cavity structure.

17. The system of claim 16 wherein the scintillator detectors are composed of inorganic material.

18. The system of claim 17 wherein the inorganic detectors are formed from at least one of the following materials:

Sodium Iodide (NaI), Cesium Iodide (CsI), Bismuth Germanate (BGO-Bi₄ Ge₃ O₁₂) and Barium Fluoride (BaF₂) and solid-state detectors including Lithium-drifted Germanium (Ge(Li)), High Purity Germanium (HPGe), and Mercuric Iodide (HgI₂).

19. The system of claim 13 wherein the inorganic detectors are formed from Sodium Iodide (NaI).

20. The system of claim 13 wherein the scintillator detectors are formed into a C-ring configuration, open at one end, and the thermal neutron means are disposed in the open end of the C-ring configuration.

21. The system of claim 13 wherein the plurality of scintillator detectors are a spaced pair of C-ring configurations, open at one end, having open ends opposite each other and separated from each other in the direction of movement of the object in the cavity structure and wherein the scintillator detectors in each of the ring configurations are in a common plane spaced from the scintillation detectors in the other C-ring configuration in the direction of movement of the object through the cavity structure.

22. The system of claim 21 additionally including means for integrating the output signals from the detectors to provide resultant signals and wherein the data processing means are operative upon the resultant signals to provide the three dimensional representation of the concentration of the particular element in the object at the different positions in the object.

23. The system of claim 21 wherein each of the spaced pair of open C-shaped ring configuration is defined by parallel sets of individual detectors.

26. The system of claim 21 wherein

side structures and top and bottom structures are disposed in the cavity structure and wherein the scintillator detectors in one of the C-ring configurations are disposed in three of the top and bottom and side structures in the cavity structure and wherein the scintillator detectors in the other C-ring configuration are disposed in three of the top and bottom and side structures in the cavity structure and wherein the fourth one of the top and bottom and side structures in one of the open C-ring configurations is opposite to the fourth one of the top and bottom and side structures in the other open C-ring configuration and wherein the open C-ring configurations are substantially parallel to each other and substantially perpendicular to the direction of movement of the object through the cavity structure.

27. The system of claim 23 wherein

side structures and top and bottom structures are disposed in the cavity structure and wherein the scintillator detectors in one of the C-ring configurations are disposed in three of the top and bottom and side structures in the cavity structure and wherein the scintillator detectors in the other C-ring configuration are disposed in three of the top and bottom and side structure in the cavity structure and wherein the fourth one of the top and bottom and side structures in one of the open C-ring configurations is opposite to the fourth one of the top and bottom and side structures in the other open C-shaped configuration and wherein the open C-ring configurations are substantially parallel to each other and substantially perpendicular to the direction of movement of the object through the cavity structures.

41. The system of claim 16 wherein the C-ring configuration is defined by three abutting sides and wherein different groups of the detectors in the plurality are disposed in the three planar sides and wherein the individual detectors in each group are operative independently of one another and independently of the detectors in the other groups.

42. The system of claim 22 wherein each of the C-ring configurations is defined by three abutting sides and wherein different groups of the individual detectors in the plurality are disposed in the three planar sides and wherein the individual detectors in each group are operative independently of one another and independently of the detectors in the other groups.

45. The system of claim 26 wherein an individual group of detectors is disposed in each of the structures defining the positions of each of the C-ring configurations and wherein the detectors in each group are operative independently of one another and independently of the detectors in the other groups.

46. The system of claim 27 wherein an individual group of detectors is disposed in each of the structures defining the positions of each of the C-ring configurations and wherein the detectors in each group are operative independently of one another and independently of the detectors in the other groups.

28. A system for detecting the presence of explosives in an object under observation by detection of a particular element, and the three-dimensional concentration of such particular element, at the different positions in the object, including,

a cavity structure for receiving the object under observation,

means stationary in the cavity structure for providing thermal neutrons to the object under observation to obtain the production from the object of gamma rays representative of the presence and concentration of the particular element in the object,

means for moving the object continuously and progressively through the cavity structure,

a plurality of detector means operative independently of one another and disposed in the cavity structure and positioned relative to the thermal neutron means and the object for detecting the gamma rays from the object, during the movement of the object continuously and progressively through the cavity structure, to produce output signals indicative at each instant of such gamma rays, and the detector means and the stationary thermal neutron means being disposed in a common plane enclosing the object,

means responsive to the output signals produced by the detector means at the progressive instants of time during the continuous and progressive movement of the object through the cavity structure for processing such output signals to indicate the presence, and the concentration on a three-dimensional basis, of the particular element at the different positions in the object.

29. A system as set forth in claim 28 wherein

the detector means constitute inorganic detectors.

30. A system as set forth in claim 28 wherein

the thermal neutron means are located at at least two progressive positions in the direction of the movement of the object through the cavity structure and wherein

the detector means are located at at least two progressive positions in the direction of the movement of the object continuously and progressively through the cavity and wherein the detectors at each of the progressive positions detect the gamma rays passing from the object as a result of the thermal neutrons from the thermal neutron means at an individual one of the progressive positions.

31. A system as set forth in claim 30 wherein

the detector means include inorganic detectors formed from at least one of the following materials:

Sodium Iodide (NaI), Cesium Iodide (CeI), Bismuth Germanate (Bi₄ Ge₃ O₁₂), Barium Fluoride (BaF₂) and solid state detectors including Lithium-drifted Germanium (GeLi), High Purity Germanium (HPGe) and Mercuric Iodide (HgI₂).

32. A system for detecting the presence of explosives in an object under observation by detection of a particular element at the differnet positions in the object, including,

a cavity structure for receiving the particular object within the cavity structure,

stationary means for producing thermal neutrons within the cavity structure to interact with the object in forming gamma rays of a particular energy,

means for providing a movement of the object continuously and progressively through the cavity structure,

a pluraity of detector means operative independently of one another and disposed within the cavity structure and positioned relative to the thermal neutron means for detecting the gamma rays from the object in progressive planes in the object, each progressive plane being transverse to the direction of movement of the object in the cavity structure, and for producing output signals representative of the gamma rays detected in each plane from the object, the detector means and the stationary thermal neutron means being disposed in a common plane enclosing the object, and

means for processing the output signals produced in the detector means at the progressive instants of time during the continuous and progressive movement of the object through the cavity structure to provide an indication of the particular element at the different positions in the object on a three-dimensional basis.

33. A system as set forth in claim 32 wherein

the thermal neutron means and the detector means are disposed relative to one another to provide for the detection by the detector means of the gamma rays passing from the object at all of the positions in the progressive planes and to produce output signals in accordance with such detection and wherein

the processing means are operative to process the signals from the detector means for the progressive planes to provide an indication of the particular element at the different positions in the object and the three-dimensional concentration of such particular element at the different positions in the object.

34. A system as set forth in claim 32 wherein

the detector means constitute inorganic detectors.

35. A system as set forth in claim 34 wherein

the moving means includes conveyor means passing through the cavity structure and supporting the object to move the object through the cavity structure.

36. A system as set forth in claim 33 wherein

the processing means includes means for producing an alarm condition in response to particular three-dimensional representations of the concentration of the particular element in the object at the different positions in the object.

37. A system as set forth in claim 33 wherein

the progressive planes are substantially perpendicular to the direction of movement of the object in the cavity structure and wherein

the detector means constitute inorganic detectors.

38. A system as set forth in claim 33 wherein

means are included for integrating the output signals from the detector means and wherein the data processing means are operative upon the integrated output signals to provide the three-dimensional representation of the concentration of the particular element in the object at the different positions in the object.