PRIMARY AND SECONDARY SCANNING IN MUON TOMOGRAPHY INSPECTION

20150212014

14/423381

August 21, 2013

Techniques and systems for using cosmic ray-produced muons to inspect objects based on an initial scanning of all objects and an additional scanning of objects that are determined by the initial scanning to potentially include one or more suspect regions. In one implementation, a system can include a primary scanner for performing the initial or primary scanning and a smaller secondary scanner for the additional or secondary scanning to provide efficient and accurate inspection of objects while maintaining a desired throughput of the inspection. In another implementation, a single scanner can be used to perform both the initial scanning and the additional scanning while maintaining a sufficient throughput of a line of objects under inspection.

Decision Sciences International Corporation (Poway, CA, US)

1. A method for inspecting objects based on muon tomography using cosmic ray-produced muons, comprising: operating a first muon tomography scanner that includes position sensitive charged particle detectors to perform an imaging scan of an object under inspection for a first imaging duration to obtain a first muon tomography image of the entire object; processing the first muon tomography image of the entire object to obtain information inside the object; generating a clearance signal when the processing of the first muon tomography image reveals no suspect region inside the object to set the first muon tomography scanner ready for receiving a next object for inspection; when the processing of the first muon tomography image reveals one or more suspect regions inside the object, removing the object from the first muon tomography scanner to place the object in a second, separate muon tomography scanner to perform an imaging scan of the object for a second imaging duration longer than the first imaging duration to obtain a second muon tomography image of only each suspect region of the object without imaging the entire object, wherein the second muon tomography scanner is configured to have a smaller imaging area covered by the position sensitive charged particle detectors to obtain an image of only a portion of the object; and while the second muon tomography scanner is being operated to further inspect the object with the one or more suspect regions, operating the first muon tomography scanner to receive a next object to inspect.

2. The method as in claim 1, comprising: including the first and second muon tomography scanners as part of a vehicle or cargo inspection system wherein the first muon tomography scanner is placed in a main traffic path in which vehicles or cargos to be inspected are lined up to pass through the first muon tomography scanner one at a time, and the second muon tomography scanner is placed off the main traffic path; and directing a vehicle or cargo in the main traffic path, that has been determined to include one or more suspect regions by the first muon tomography scanner, to leave the main traffic path and to enter the second muon tomography scanner for further inspection while continuing operating the first muon tomography scanner to inspect subsequent vehicles or cargos in the main traffic path.

3. The method as in claim 1, further comprising: configuring the first muon tomography scanner to have a capability of detecting a radiation emission from an object that is different from muons.

4. The method as in claim 3, wherein: the first muon tomography scanner is configured to have a capability of detecting gamma rays in addition to detection of muons.

5. The method as in claim 4, further comprising: configuring the second muon tomography scanner to have a capability of detecting gamma rays in addition to detection of muons.

6. The method as in claim 3, wherein: configuring the second muon tomography scanner to have a capability of detecting the radiation emission as the first muon tomography scanner.

7. A method for inspecting objects based on tomography using cosmic ray-produced muons, comprising: operating a muon tomography scanner that includes position sensitive charged particle detectors to perform an imaging scan of an object in a line of objects under inspection for an imaging duration to obtain a muon tomography image of the entire object; processing the muon tomography image of the entire object to obtain information on one or more suspect regions inside the object; generating a clearance signal when the processing of the muon tomography image reveals no suspect region inside the object to set the muon tomography scanner ready for receiving a next object for inspection; and when the processing of the muon tomography image reveals one or more suspect regions inside the object, operating the muon tomography scanner to scan the object for an additional scan time that is sufficiently long to make an affirmative decision on whether or not the one or more suspect regions inside the object constitute a threat.

8. The method as in claim 7, wherein: the scanning of the object for the additional scan time is conducted while keeping other objects in the line to wait.

9. The method as in claim 7, wherein: the scanning of the object for the additional scan time is conducted at a later time while placing one or more subsequent objects in the line in the muon tomography scanner to undergo imaging scan without delay, and the method further comprises: directing the object that has been determined to include one or more suspect regions move out of the line of the objects to a waiting position while conducting imaging scan on the one or more subsequent objects in the line; and after a period of waiting for further inspection when the traffic flow in the line permits, directing the object in the waiting position to move back to the muon tomography scanner to complete the scanning of the object for the additional scan time to make an affirmative decision on whether or not the one or more suspect regions inside the object constitute a threat.

10. The method as in claim 7, comprising: including the muon tomography scanner as part of a vehicle or cargo inspection system wherein the muon tomography scanner is placed in a traffic path in which vehicles or cargo to be inspected are lined up to pass through the muon tomography scanner one at a time; directing a vehicle or cargo in the traffic path, that has been determined to include one or more suspect regions by the muon tomography scanner to move out of the line of the traffic path to a waiting position while conducting imaging scans on other vehicles or cargo in the traffic path; and after a period of waiting for further inspection when the traffic flow permits, directing the vehicle or cargo in the waiting position to move back to the muon tomography scanner to resume the extended scanning of the object to make an affirmative decision on whether or not the one or more suspect regions inside the vehicle or cargo constitute a threat.

11. A system for inspecting objects based on muon tomography using cosmic ray-produced muons, comprising: a main inspection traffic path along which objects under inspection are lined up in sequence to move in a common direction; a first muon tomography scanner located in the main inspection traffic path to inspect the objects in sequence, the first muon tomography scanner configured to include position sensitive charged particle detectors to perform an imaging scan of an object under inspection for a first imaging duration to obtain a first muon tomography image of the object, and the first muon tomography scanner further configured to have a sufficiently large imaging area covered by the position sensitive charged particle detectors to obtain a full image of the entire object; a second, separate muon tomography scanner that includes position sensitive charged particle detectors to perform an imaging scan of the object for a second imaging duration longer than the first imaging duration to obtain a second muon tomography image of only each suspect region of the object without imaging the entire object, wherein the second muon tomography scanner is configured to have a smaller imaging area covered by the position sensitive charged particle detectors to obtain an image of only a portion of the object, and the second muon tomography scanner is located at a second location off the main inspection traffic path without interfering movement of the objects in the main inspection traffic path; and an inspection control mechanism that processes the first muon tomography image of the object, generates a clearance signal when the processing of the first muon tomography image reveals no suspect region inside the object to set the first muon tomography scanner ready for receiving a next object for inspection, and issues an instruction for removing the object from the first muon tomography scanner to place the object in the second muon tomography scanner for further inspection if the first muon tomography image reveals one or more suspect regions inside the object, while operating the first muon tomography scanner to receive a next object to inspect.

12. The system as in claim 11, wherein: the first muon tomography scanner is configured to have a capability of detecting a radiation emission from an object that is different from muons.

13. The system as in claim 12, wherein: the first muon tomography scanner is configured to have a capability of detecting gamma rays in addition to detection of muons.

14. The system as in claim 13, wherein: the second muon tomography scanner is configured to have a capability of detecting gamma rays in addition to detection of muons.

15. The system as in claim 12, wherein: the second muon tomography scanner is configured to have a capability of detecting the radiation emission as the first muon tomography scanner.

16. The system as in claim 11, wherein: each of the first and second muon tomography scanner includes: a first set of position sensitive charged particle detectors located on a first side of an object holding area to measure positions and directions of incident charged particles towards the object holding area; a second set of position sensitive charged particle detectors located on a second side of the object holding area opposite to the first side to measure positions and directions of outgoing charged particles exiting the object holding area; and a signal processing unit to receive data of measured signals of the incoming charged particles from the first set of position sensitive charged particle detectors and measured signals of the outgoing charged particles from the second set of position sensitive charged particle detectors, wherein the signal processing unit is configured to analyze scattering of the charged particles in the materials within the object holding area based on the measured incoming and outgoing positions and directions of charged particles to obtain a tomographic profile or the spatial distribution of scattering centers within the object holding area.

17. The system as in claim 11, wherein: the inspection control mechanism is configured to obtain information on a traffic flow of objects to be inspected in the main inspection traffic path and, based on the obtained information on the traffic flow, to determine whether to hold the object at the first muon tomography scanner to perform a further scanning of the object in the first muon tomography scanner if the first muon tomography image reveals one or more suspect regions inside the object.

18. The system as in claim 17, wherein: when the obtained information on the traffic flow indicates a low traffic, the inspection control mechanism is configured to hold the object at the first muon tomography scanner to perform a further scanning of the object in the first muon tomography scanner if the first muon tomography image reveals one or more suspect regions inside the object; and when the obtained information on the traffic flow indicates a high traffic, the inspection control mechanism is configured to issue the instruction for removing the object from the first muon tomography scanner to place the object in the second muon tomography scanner for further inspection if the first muon tomography image reveals one or more suspect regions inside the object, while operating the first muon tomography scanner to receive a next object to inspect.

19. The system as in claim 11, wherein each of the first and second muon tomography scanners is configured to: reconstruct a trajectory of a muon through the object based on signals from the position sensitive charged particle detectors; measure an incoming momentum and an outgoing momentum of a muon based on signals from the position sensitive charged particle detectors; determine a spatial distribution of a scattering density within the object; and using information of the trajectory, momentum and spatial distribution of the scattering density in the object to construct a tomographic profile inside the object.

20. The system as in claim 11, wherein: the position sensitive charged particle detectors in each of the first and second muon tomography scanners include: first position sensitive charged particle detectors on one side of the object to receive and measure incoming muons towards the object; and second position sensitive charged particle detectors on an opposite side of the object o receive and measure outgoing muons that pass through the object, wherein each of the first and second muon tomography scanners is configured to use measurements of muons by both the first position sensitive charged particle detectors and the second position sensitive charged particle detectors to obtain a muon tomography image of the object.

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edspap.20150212014