Binocular method and apparatus for stoichiometric analysis and imaging using subatomic particle activation
First Claim
1. A method of providing non-invasive, stoichiometric analysis and imaging of a substance comprising atomic nuclei which emit one or more gamma rays having energies characteristic of the atomic nuclei in response to neutron irradiation, the method comprising:
- emitting a first plurality of neutron/alpha particle pairs from a first location separate from the substance, each pair comprising a neutron having an energy of approximately 14 MeV and a corresponding alpha particle, the neutron and the alpha particle generated by the same nuclear reaction, the neutron and the alpha particle propagating in substantially opposite directions;
detecting alpha particles from the first location propagating generally within a first solid angle with respect to the first location away from the substance, the first solid angle generally centered along a first line;
irradiating a region of the substance with neutrons from the first location propagating generally within the first solid angle toward the substance, the region emitting gamma rays in response thereto;
emitting a second plurality of neutron/alpha particle pairs from a second location separate from the substance, each pair comprising a neutron having an energy of approximately 14 MeV and a corresponding alpha particle, the neutron and the alpha particle generated by the same nuclear reaction, the neutron and the alpha particle propagating in substantially opposite directions, the second location spaced from the first location;
detecting alpha particles from the second location propagating generally within a second solid angle with respect to the second location away from the substance, the second solid angle generally centered along a second line different from the first line;
irradiating the region of the substance with neutrons from the second location propagating generally within the second solid angle toward the substance, the region emitting gamma rays in response thereto;
detecting at least a portion of the gamma rays emitted by the substance in response to being irradiated by the neutrons from the first location and by the neutrons from the second location, and generating a plurality of gamma detection signals in response thereto;
energy-filtering the plurality of gamma detection signals to generate a plurality of energy-filtered gamma signals by passing gamma detection signals corresponding to detected gamma rays having energies characteristic of the atomic nuclei of the substance and by rejecting gamma detection signals corresponding to detected gamma rays having energies which are not characteristic of the atomic nuclei of the substance;
detecting coincidences between the energy-filtered gamma signals and the detected alpha particles from the first location; and
detecting coincidences between the energy-filtered gamma signals and the detected alpha particles from the second location.
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Abstract
An apparatus and method for detecting, locating, and analyzing chemical compounds located within a test subject using subatomic particle activation. In a first embodiment, an excitation source excites a target to simultaneously produce beams each consisting of certain subatomic species, for example fast neutrons and alpha particles. The test subject (and chemical compounds contained therein) is irradiated by the fast neutrons, thereby stimulating the emission of prompt gamma rays. Gamma and alpha detectors are positioned relative to the test subject and target(s) so as to detect the emitted prompt gamma rays and alpha particles in substantial coincidence, and the known physical relationship between the beams is used to spatially locate the activated chemical compound. Energy spectra derived from the gamma detectors are filtered to eliminate all non-relevant spectral artifacts, thereby 1) permitting the creation of a plurality of parallel coincidence channels; 2) reducing the subsequent signal processing required; and 3) increasing the overall accuracy and efficiency of the chemical compound identification and analysis processes. In a second embodiment, thermal neutron-induced gamma emissions are detected and analyzed in conjunction with the fast neutron-induced gammas to provide a warning signal of the possible presence of certain types of contraband. A multi-beam/multi-target embodiment is also disclosed for more accurate spatial location. A method for calibrating and evaluating the efficacy of the system under varying test parameters is further disclosed.
69 Citations
22 Claims
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1. A method of providing non-invasive, stoichiometric analysis and imaging of a substance comprising atomic nuclei which emit one or more gamma rays having energies characteristic of the atomic nuclei in response to neutron irradiation, the method comprising:
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emitting a first plurality of neutron/alpha particle pairs from a first location separate from the substance, each pair comprising a neutron having an energy of approximately 14 MeV and a corresponding alpha particle, the neutron and the alpha particle generated by the same nuclear reaction, the neutron and the alpha particle propagating in substantially opposite directions;
detecting alpha particles from the first location propagating generally within a first solid angle with respect to the first location away from the substance, the first solid angle generally centered along a first line;
irradiating a region of the substance with neutrons from the first location propagating generally within the first solid angle toward the substance, the region emitting gamma rays in response thereto;
emitting a second plurality of neutron/alpha particle pairs from a second location separate from the substance, each pair comprising a neutron having an energy of approximately 14 MeV and a corresponding alpha particle, the neutron and the alpha particle generated by the same nuclear reaction, the neutron and the alpha particle propagating in substantially opposite directions, the second location spaced from the first location;
detecting alpha particles from the second location propagating generally within a second solid angle with respect to the second location away from the substance, the second solid angle generally centered along a second line different from the first line;
irradiating the region of the substance with neutrons from the second location propagating generally within the second solid angle toward the substance, the region emitting gamma rays in response thereto;
detecting at least a portion of the gamma rays emitted by the substance in response to being irradiated by the neutrons from the first location and by the neutrons from the second location, and generating a plurality of gamma detection signals in response thereto;
energy-filtering the plurality of gamma detection signals to generate a plurality of energy-filtered gamma signals by passing gamma detection signals corresponding to detected gamma rays having energies characteristic of the atomic nuclei of the substance and by rejecting gamma detection signals corresponding to detected gamma rays having energies which are not characteristic of the atomic nuclei of the substance;
detecting coincidences between the energy-filtered gamma signals and the detected alpha particles from the first location; and
detecting coincidences between the energy-filtered gamma signals and the detected alpha particles from the second location. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A method of providing non-invasive, stoichiometric analysis and imaging of a substance comprising atomic nuclei which emit one or more gamma rays having energies characteristic of the atomic nuclei in response to neutron irradiation, the method comprising:
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emitting neutron/alpha particle pairs from a first location separate from the substance and from a second location separate from the substance, the second location spaced from the first location, each pair comprising a neutron and a corresponding alpha particle propagating in substantially opposite directions;
detecting alpha particles from the first location propagating generally within a first solid angle with respect to the first location away from the substance and alpha particles from the second location propagating generally within a second solid angle with respect to the second location away from the substance, the first solid angle generally centered along a first line, the second solid angle generally centered along a second line different from the first line;
irradiating a region of the substance with neutrons from the first location propagating generally within the first solid angle toward the substance and with neutrons from the second location propagating generally within the second solid angle toward the substance, the region emitting gamma rays in response thereto; and
detecting at least a portion of the gamma rays emitted by the substance in response to being irradiated by the neutrons from the first location and by the neutrons from the second location. - View Dependent Claims (18, 19)
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20. A method of providing non-invasive, stoichiometric analysis and imaging of a substance comprising atomic nuclei which emit one or more gamma rays having energies characteristic of the atomic nuclei in response to neutron irradiation, the method comprising:
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emitting neutron/alpha particle pairs from a plurality of locations spaced from the substance and from one another, each pair comprising a neutron and a corresponding alpha particle propagating in substantially opposite directions;
detecting alpha particles from the plurality of locations propagating away from the substance;
irradiating a region of the substance with neutrons from the plurality of locations propagating toward the substance, the neutrons corresponding to the detected alpha particles, the region emitting gamma rays in response thereto; and
detecting at least a portion of the gamma rays emitted by the substance in response to being irradiated by the neutrons from the first location and by the neutrons from the second location. - View Dependent Claims (21, 22)
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Specification