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US 2014/0270034 A1Published application
Detection of Special Nuclear Material and Other Contraband by Prompt and/or Delayed Signatures from Photofission
AssigneeVarex Imaging Corporation
InventorsJames CLAYTON, Edward J. Seppi
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Abstract
In accordance with embodiments of the invention, at least the potential presence of Special Nuclear Material (“SNM”) is determined by the detection of prompt neutrons, prompt gamma rays, delayed neutrons, and/or delayed gamma rays from photofission, via time-of-flight (“TOF”) spectroscopic methods. Methods and systems are disclosed.
Claims33
A method of examining contents of an object, the method comprising:
- scanning an object by first and second consecutive radiation pulses;
- checking for the detection of gamma rays during a first time period starting after the scanning by the first radiation pulse and ending before a start of scanning by the second radiation pulse, the first time period being based, at least in part, on a first expected arrival time of gamma rays at a first detector resulting from interaction of the first radiation pulse with Special Nuclear Material within the object, if any;
- checking for the detection of neutrons during a second time period starting after the scanning by the first radiation pulse and ending before a start of scanning by the second radiation pulse, the second time period being based, at least in part, on a second expected arrival time of neutrons at a second detector resulting from interaction of the first radiation pulse with Special Nuclear Material within the object, if any;
- and
- determining whether the object at least potentially contains Special Nuclear Material based, at least in part, on the check for the detection of the gamma rays and the check for the detection of neutrons.
2 more elements
A method of examining contents of an object, the method comprising:
- scanning an object by a plurality of consecutive macropulses of radiation, the consecutive macropulses comprising respective pluralities of consecutive micropulses of radiation, wherein consecutive macropulses are separated by a greater amount of time than consecutive micropulses;
- checking for the detection of prompt gamma rays in respective first time periods between respective consecutive micropulses of radiation and not during any of the respective consecutive micropulses, the respective first time periods being based, at least in part, on respective expected arrival times of prompt gamma rays at a first detector resulting from photofission within the object, if any, induced by a respective consecutive micropulse;
- checking for the detection of prompt neutrons in respective second time periods between respective consecutive micropulses of radiation and not during any of the respective consecutive micropulses, the respective second time periods being based, at least in part, on respective expected arrival times of prompt neutrons at a second detector resulting from photofission within the object, if any, induced by a respective consecutive micropulse;
- checking for the detection of delayed gamma rays in respective third time periods between respective consecutive macropulses of radiation and not during either of the respective consecutive macropulses, the respective third time periods being based, at least in part, on respective expected arrival times of delayed gamma rays at the first detector resulting from photofission within the object, if any, induced by a respective consecutive macropulse;
- and
- checking for the detection of delayed neutrons in respective fourth time periods between respective consecutive macropulses of radiation and not during any of the respective consecutive macropulses, the respective fourth time periods being based, at least in part, on respective expected arrival times of delayed neutrons at the second detector resulting from photofission within the object, if any, induced by the respective consecutive macropulse;
- and
- determining whether the object contains Special Nuclear Material based, at least in part, on the checks for the detection of the prompt gamma rays, prompt neutrons, delayed gamma rays, and/or delayed neutrons.
5 more elements
A system for examining contents of an object, the system comprising:
- a support to support an object;
- a radiation source configured to generate first and second radiation pulses to scan the object;
- at least one first detector positioned to detect gamma rays resulting from interaction of the radiation beam with the object;
- at least one second detector positioned to detect prompt neutrons resulting from interaction of the radiation beam with the object;
- at least one processor configured to:
- check for the detection of gamma rays during a first time period starting after the scanning by the first radiation pulse and ending before a start of scanning by the second radiation pulse, the first time period being based, at least in part, on first expected arrival time of gamma rays at the first detector resulting from interaction of the first radiation pulse with Special Nuclear Material within the object, if any;
- check for the detection of neutrons in second time periods starting after the scanning by the first radiation pulse and ending before a start of scanning by the second radiation pulse, the second time period being based, at least in part, on second expected arrival time of neutrons at the second detector resulting from interaction of the respective first of the respective consecutive radiation pulses with Special Nuclear Material within the object, if any;
- and
- determine whether the object contains Special Nuclear Material based, at least in part, on the check for the detection of the gamma rays and the check for the detection of neutrons.
6 more elements
Dependencies are inferred from the claim text.