System and method for target inspection using discrete photon counting and neutron detection

• US 7,335,887 B1
• Filed: 06/02/2006
• Issued: 02/26/2008
• Est. Priority Date: 10/23/1995
• Status: Expired due to Fees

• Current Assignee: Leidos, Inc. (Leidos Holdings, Inc.)
• Original Assignee: Science Applications International Corporation
• Inventors: Verbinski, Victor, Madson, Dan
• Primary Examiner(s): Hannaher; Constantine
• Application Number:
  US11/445,112
• Time in Patent Office: 634 Days
• Field of Search: 250/358.1, 250/359.1, 250/360.1, 250/391, 378/57, 378/58, 378/146
• US Class Current: 250/358.1
• CPC Class Codes: G01N 23/02 by transmitting the radiation through the material
• CPC Class Codes: G01V 5/22 Active interrogation, i.e. by irradiating objects or goods using external radiation sources, e.g. using gamma rays or cosmic rays
• CPC Class Codes: G01V 5/232 having relative motion between the source, detector and object other than by conveyor G01V5/226 takes precedence

Abstract

Described herein is system for the inspection of a target object. The system may include a gamma radiation source, a gamma detector and an image processor coupled to the gamma detector. When the inspection system is operating in a first active mode for imaging a target object, the gamma radiation source directs radiation at a target object, the radiation passes through the target object, and the image processor images the target object based on an output of the gamma detector. When the dual-mode system is operating in a second passive mode for imaging a target object, the target object is scanned by a neutron detector for radiation that is emitted by the target object, the emitted radiation from the target object is detected by the neutron detector and an indicator indicates the presence of the emitted radiation.

Claims

1. A method for inspecting a target object comprising:

directing radiation from a radiation source at the target object;

detecting at least a portion of the radiation from the radiation source at a first detector after the at least a portion of the radiation passes through the target object;

scanning the target object with a helium neutron detector, the helium neutron detector being capable of scanning in a first and a second mode including;

a first mode comprising detecting with the helium neutron detector an emission from the target object and indicating the presence of the emission when the emission is above a predetermined threshold level; and

a second mode comprising detecting with the helium neutron detector a first background emission and a second emission from the target object, comparing the first and second emissions and indicating the presence of the second emission when the second emission is determined to be a predetermined deviation above the first emission;

identifying spurious counts representative of emissions received at the helium neutron detector including;

detecting counts received at the helium neutron detector at predetermined time intervals;

comparing the detected counts from a selected time interval with counts from the remaining time intervals;

determining of there is a spurious count in the selected time interval as compared to the remaining time intervals; and

disregarding the spurious count, if identified.

2. The method according to claim 1, wherein the presence of an emission is indicated by a light.

3. The method according to claim 1, wherein the presence of an emission is indicated by a sound alarm.

4. The method according to claim 1, further comprising passing the target object between the radiation source and the first and helium neutron detectors.

5. The method according to claim 1, wherein the first detector is a photon detector.

6. The method according to claim 5, further comprising:

discretely counting photons received by the first detector; and

generating a display of the target object in response to discretely counting the photons received by the first detector.

7. A method for inspecting a target object comprising:

deploying a boom connected on a first end to a movable platform and connected on a second end to a radiation source such that the target object can pass between the movable platform and the radiation source;

directing radiation from a radiation source at the target object;

detecting the radiation from the radiation source at a first detector located on the movable platform after the radiation passes through the target object;

detecting radiation emitted from the target object with a helium neutron detector located on the movable platform, the helium neutron detector being capable of detecting radiation in a first and a second mode including;

a first mode comprising detecting with the helium neutron detector an emission from the target object and indicating the presence of the emission when the emission is above a predetermined threshold level; and

a second mode comprising detecting with the helium neutron detector a first background emission and a second emission from the target object, comparing the first and second emissions and indicating the presence of the second emission when the second emission is determined to be a predetermined deviation above the first emission;

identifying spurious counts representative of emissions received at the helium neutron detector including;

detecting counts received at the helium neutron detector at predetermined time intervals;

comparing the detected counts from a selected time interval with counts from the remaining time intervals;

determining of there is a spurious count in the selected time interval as compared to the remaining time intervals; and

disregarding the spurious count, if identified.

8. The method according to claim 7, wherein the presence of an emission is indicated by a light.

9. The method according to claim 7, wherein the presence of an emission is indicated by a sound alarm.

10. The method according to claim 7, wherein the first detector is a photon detector.

11. The method according to claim 10, further comprising:

discretely counting photons received by the first detector; and

generating a display of the target object in response to discretely counting the photons received by the first detector.

12. A method for inspecting a target object comprising:

imaging the target object using gamma radiation data collected with a first detector; and

indicating the presence or absence of a neutron emission from the target object using data collected from a helium neutron detector, the helium neutron detector being capable of detecting radiation in a first and a second mode including;

a first mode comprising detecting with the helium neutron detector an emission from the target object and indicating the presence of the emission when the emission is above a predetermined threshold level; and

a second mode comprising detecting with the helium neutron detector a first background emission and a second emission from the target object, comparing the first and second emissions and indicating the presence of the second emission when the second emission is determined to be a predetermined deviation above the first emission;

identifying spurious counts representative of emissions received at the helium neutron detector including;

detecting counts received at the helium neutron detector at predetermined time intervals;

comparing the detected counts from a selected time interval with counts from the remaining time intervals;

determining of there is a spurious count in the selected time interval as compared to the remaining time intervals; and

disregarding the spurious count, if identified.

13. The method according to claim 12, wherein the presence of a neutron emission from the target object is indicated by an illumination of a red light and the absence of a neutron emission from the target object is indicated by an illumination of a green light.

14. The method according to claim 12, wherein the helium neutron detector is an ³He detector.