Integrated substance detection and identification system

• US 5,557,108 A
• Filed: 06/15/1995
• Issued: 09/17/1996
• Est. Priority Date: 10/25/1993
• Status: Expired due to Term

• Current Assignee: Nova R&D Incorporated (Kromek Group PLC)
• Original Assignee: Tumay O. Tumer
• Inventors: Tumer, Tumay O.
• Primary Examiner(s): Hannaher, Constantine
• Application Number:
  US08/490,959
• Time in Patent Office: 460 Days
• Field of Search: 250/390.02, 250/392, 250/391, 250/390.12, 250/390.05, 250/390.04
• US Class Current: 250/390.04
• CPC Class Codes: G01N 23/204 using neutrons
• CPC Class Codes: G01V 5/222 measuring scattered radiation
• CPC Class Codes: G01V 5/223 Mixed interrogation beams, e.g. using more than one type of radiation beam

Abstract

An apparatus and method for non-destructively detecting and identifying narcotics, explosives, and other forms of contraband concealed within a container or otherwise hidden from view. A radioactive source is used in conjunction with both neutron and gamma ray detector arrays. Depending upon the desired accuracy as well as the accessibility to all sides of the container, both back scattered and forward scattered radiation can be measured. Multiple detection systems mounted along different axes allow pseudo three dimensional images of the container in question as well as its contents to be produced.

Claims

1. A method for identifying substances disposed behind a barrier having a front, said method comprising the steps of:

positioning a radioactive source on the front side of the barrier, said source providing a flux of gamma rays and fast neutrons;

positioning a detector near said source, said detector capable of measuring a flux of scattered gamma rays and generating a gamma ray output signal corresponding to a magnitude of said scattered gamma rays, and said detector capable of measuring a flux of scattered neutrons and generating a neutron output signal corresponding to a magnitude of said scattered neutrons; and

comparing the magnitude of said detector output signals to determine the identity of substances disposed behind said barrier.

2. A method for identifying substances disposed behind a barrier having a front, said method comprising the steps of:

positioning a first source on the front side of the barrier, said first source providing a flux of gamma rays;

positioning a first detector near said first source, said first detector capable of measuring a flux of scattered gamma rays and generating a gamma ray output signal corresponding to a magnitude of said scattered gamma rays;

positioning a second source proximate to said first source on the front side of the barrier, said second source providing a flux of neutrons;

positioning a second detector near said second source, said second detector capable of measuring a flux of scattered neutrons and generating a neutron output signal corresponding to a magnitude of said scattered neutrons; and

comparing said first detector output signal and said second detector output signal to determine the identity of substances disposed behind said barrier.

3. A system for identifying substances behind a surface, comprising:

a radioactive source for providing a flux of gamma rays and fast neutrons;

a detector proximate to said radioactive source, said detector measuring a flux of scattered gamma rays and generating a gamma ray output signal corresponding to a magnitude of said scattered gamma rays, and said detector measuring a flux of scattered neutrons and generating a neutron output signal corresponding to a magnitude of said scattered neutrons; and

an output device, coupled to said detector, for converting said detector output signals to a format indicating the identity of said substances located behind said surface.

4. A method for identifying substances disposed within a container, said container having a first side, a second side, a top, and a bottom, said method comprising the steps of:

positioning a source of neutrons on the first side of the container;

positioning a source of gamma rays on the first side of the container;

positioning a first detector array near said source of neutrons, said first detector array capable of measuring a magnitude of back scattered neutrons at a plurality of locations and generating a first plurality of output signals corresponding to said magnitude of back scattered neutrons;

positioning a second detector array near said source of gamma rays, said second detector array capable of measuring a magnitude of back scattered gamma rays at said plurality of locations and generating a second plurality of output signals corresponding to said magnitude of back scattered gamma rays;

positioning a third detector array on the second side of the container and opposite said source of neutrons, said third detector array capable of measuring a magnitude of forward scattered neutrons at said plurality of locations and generating a third plurality of output signals corresponding to said magnitude of forward scattered neutrons;

positioning a fourth detector array on the second side of the container and opposite said source of gamma rays, said fourth detector array capable of measuring a magnitude of forward scattered gamma rays at said plurality of locations and generating a fourth plurality of output signals corresponding to said magnitude of forward scattered gamma rays; and

analyzing said first, second, third, and fourth pluralities of output signals to identify substances disposed within the container.

5. The method of claim 4, further comprising the steps of:

positioning a second source of neutrons on the top side of the container;

positioning a second source of gamma rays on the top side of the container;

positioning a fifth detector array near said second source of neutrons, said fifth detector array capable of measuring a magnitude of back scattered neutrons at a plurality of locations and generating a fifth plurality of output signals corresponding to said magnitude of back scattered neutrons;

positioning a sixth detector array near said second source of gamma rays, said sixth detector array capable of measuring a magnitude of back scattered gamma rays at said plurality of locations and generating a sixth plurality of output signals corresponding to said magnitude of back scattered gamma rays;

positioning a seventh detector array on the bottom side of the container and opposite said second source of neutrons, said seventh detector array capable of measuring a magnitude of forward scattered neutrons at said plurality of locations and generating a seventh plurality of output signals corresponding to said magnitude of forward scattered neutrons;

positioning a eighth detector array on the bottom side of the container and opposite said second source of gamma rays, said eighth detector array capable of measuring a magnitude of forward scattered gamma rays at said plurality of locations and generating a eighth plurality of output signals corresponding to said magnitude of forward scattered gamma rays; and

analyzing said fifth, sixth, seventh, and eighth pluralities of output signals to identify substances disposed within the container.

6. The method of claim 5, further comprising the steps of:

conveying the container from a first position to a second position, wherein at said first position said first and second sources of neutrons and said first and second sources of gamma rays are positioned at a leading edge of the container, and wherein at said second position said first and second sources of neutrons and said first and second sources of gamma rays are positioned at a trailing edge of the container;

forming a first image of said container and said substances disposed within said container from the plurality of output signals from said first detector array;

forming a second image of said container and said substances disposed within said container from the plurality of output signals from said second detector array;

forming a third image of said container and said substances disposed within said container from the plurality of output signals from said third detector array;

forming a fourth image of said container and said substances disposed within said container from the plurality of output signals from said fourth detector array;

forming a fifth image of said container and said substances disposed within said container from the plurality of output signals from said fifth detector array;

forming a sixth image of said container and said substances disposed within said container from the plurality of output signals from said sixth detector array;

forming a seventh image of said container and said substances disposed within said container from the plurality of output signals from said seventh detector array;

forming a eighth image of said container and said substances disposed within said container from the plurality of output signals from said eighth detector array; and

combining said first, second, third, fourth, fifth, sixth, seventh, and eighth images to form a pseudo three dimensional image of said container and said substances contained within said container.

7. The method of claim 6, further comprising the step of combining images to form a composite image, said images selected from the group consisting of said first image, said second image, said third image, said fourth image, said fifth image, said sixth image, said seventh image, and said eighth image.

8. The method of claim 4, wherein a single source provides said neutrons and said gamma rays.

9. The method of claim 8, wherein said single source is a line source.

10. The method of claim 4, wherein a single detector array functions as said first detector array and as said second detector array.

11. The method of claim 4, further comprising the step of conveying the container from a first position to a second position, wherein at said first position said source of neutrons and said source of gamma rays are positioned at a leading edge of the container, and wherein at said second position said source of neutrons and said source of gamma rays are positioned at a trailing edge of the container.

12. The method of claim 11, further comprising the steps of:

forming a first image of said container and said substances disposed within said container from the plurality of output signals from said first detector array;

forming a second image of said container and said substances disposed within said container from the plurality of output signals from said second detector array;

forming a third image of said container and said substances disposed within said container from the plurality of output signals from said third detector array; and

forming a fourth image of said container and said substances disposed within said container from the plurality of output signals from said fourth detector array.

13. The method of claim 12, further comprising the step of combining images to form a composite image, said images selected from the group consisting of said first image, said second image, said third image, and said fourth image.

14. The method of claim 13, further comprising the steps of:

positioning a source of x-rays on the first side of the container;

positioning an x-ray detector array on the second side of the container and opposite said source of x-rays, said x-ray detector array capable of measuring a flux of x-rays at said plurality of locations and generating a plurality of output signals corresponding to said flux of x-rays;

generating an x-ray image of said container and said substances disposed within said container; and

combining said x-ray image and said composite image to form a single image of said container and said substances disposed within said container.

15. The method of claim 4, wherein said analyzing step further comprises the steps of:

comparing said first plurality of output signals to a lookup table of known neutron back scatter characteristics for a plurality of preselected substances;

comparing said second plurality of output signals to a lookup table of known gamma ray back scatter characteristics for said plurality of preselected substances;

comparing said third plurality of output signals to a lookup table of known neutron forward scatter characteristics for said plurality of preselected substances; and

comparing said fourth plurality of output signals to a lookup table of known gamma ray forward scatter characteristics for said plurality of preselected substances.

16. The method of claim 4, further comprising the steps of:

selecting at least one detector from the group of detector arrays consisting of said first, second, third, and fourth detector arrays;

determining an energy spectrum, said energy spectrum measured by said selected detector; and

anaylzing said energy spectrum to identify said substances disposed within the container.

17. The method of claim 4, wherein said substances disposed within said container are identified as either non-contraband substances or contraband substances.

18. A system for identifying substances within a container, said container having a first side, a second side, a top, and a bottom, said system comprising:

a source of neutrons positioned on the first side of the container;

a source of gamma rays positioned on the first side of the container;

a first detector array proximate said source of neutrons, said first detector array capable of measuring a magnitude of back scattered neutrons at a plurality of locations and generating a first plurality of output signals corresponding to said magnitude of back scattered neutrons;

a second detector array proximate said source of gamma rays, said second detector array capable of measuring a magnitude of back scattered gamma rays at said plurality of locations and generating a second plurality of output signals corresponding to said magnitude of back scattered gamma rays;

a third detector array on the second side of the container and opposite said source of neutrons, said third detector array capable of measuring a magnitude of forward scattered neutrons at said plurality of locations and generating a third plurality of output signals corresponding to said magnitude of forward scattered neutrons;

a fourth detector array on the second side of the container and opposite said source of gamma rays, said fourth detector array capable of measuring a magnitude of forward scattered gamma rays at said plurality of locations and generating a fourth plurality of output signals corresponding to said magnitude of forward scattered gamma rays; and

a first computer coupled to said first, second, third, and fourth detector arrays, said first computer analyzing said output signals to identify substances disposed within the container.

19. The system of claim 18, further comprising:

a second source of neutrons on the top side of the container;

a second source of gamma rays on the top side of the container;

a fifth detector array proximate said second source of neutrons, said fifth detector array capable of measuring a magnitude of back scattered neutrons at a plurality of locations and generating a fifth plurality of output signals corresponding to said magnitude of back scattered neutrons;

a sixth detector array proximate said second source of gamma rays, said sixth detector array capable of measuring a magnitude of back scattered gamma rays at said plurality of locations and generating a sixth plurality of output signals corresponding to said magnitude of back scattered gamma rays;

a seventh detector array on the bottom side of the container and opposite said second source of neutrons, said seventh detector array capable of measuring a magnitude of forward scattered neutrons at said plurality of locations and generating a seventh plurality of output signals corresponding to said magnitude of forward scattered neutrons;

a eighth detector array on the bottom side of the container and opposite said second source of gamma rays, said eighth detector array capable of measuring a magnitude of forward scattered gamma rays at said plurality of locations and generating a eighth plurality of output signals corresponding to said magnitude of forward scattered gamma rays; and

a second computer coupled to said fifth, sixth, seventh, and eighth detector arrays, said second computer analyzing said output signals to identify substances disposed within the container.

20. The system of claim 19, wherein said second computer and said first computer are the same computer.

21. The system of claim 18, wherein said source of neutrons and said source of gamma rays are the same source.

22. The system of claim 18, wherein said first detector array and said second detector array are the same detector array.

23. The system of claim 18, further comprising a conveying device for conveying the container from a first position to a second position, wherein at said first position said source of neutrons and said source of gamma rays are positioned at a leading edge of the container, and wherein at said second position said source of neutrons and said source of gamma rays are positioned at a trailing edge of the container.

24. The system of claim 23, wherein said first computer forms a first image of said container and said substances disposed within said container from the plurality of output signals from said first detector array, a second image of said container and said substances disposed within said container from the plurality of output signals from said second detector array, a third image of said container and said substances disposed within said container from the plurality of output signals from said third detector array, and a fourth image of said container and said substances disposed within said container from the plurality of output signals from said fourth detector array, and wherein said first, second, third, and fourth images are displayed on a display screen coupled to said first computer.

25. The system of claim 24, wherein said first computer forms a composite image of said container and said substances disposed within said container by combining images selected from the group consisting of said first image, said second image, said third image, and said fourth image, and wherein said composite image is displayed on said display screen.

26. The system of claim 25, further comprising:

a source of x-rays proximate the first side of the container;

an x-ray detector array on the second side of the container and opposite said source of x-rays, said x-ray detector array capable of measuring a flux of x-rays at said plurality of locations and generating a plurality of output signals corresponding to said flux of x-rays; and

wherein said first computer is coupled to said x-ray detector array, said first computer generating an x-ray image of said container and said substances disposed within said container, and wherein said display screen displays said x-ray image simultaneously with said composite image.

27. A method for identifying substances disposed within a container, said container atop a conveying device, said method comprising the steps of:

positioning a source of neutrons and gamma rays above said conveying device;

positioning a first detector proximate to said source, said first detector capable of measuring a flux of back scattered neutrons and back scattered gamma rays and generating an output signal corresponding to said flux of back scattered neutrons and an output signal corresponding to said flux of back scattered gamma rays;

positioning a second detector below said conveying device and opposite said source, said second detector capable of measuring a flux of forward scattered neutrons and forward scattered gamma rays and generating an output signal corresponding to said flux of forward scattered neutrons and an output signal corresponding to said flux of forward scattered gamma rays;

conveying said container between said first detector and said second detector; and

analyzing said output signals to identify said substances within said container.