Method for detecting an explosive in an object under investigation
First Claim
1. A method for detecting an explosive in an object under investigation, comprising the following steps:
- (a) initially exposing the object under investigation to X-rays for purposes of detecting whether the object contains a nitrogen-containing explosive having an average density range of 1.25 to 2.00 g/cm3;
(b) recording the X-rays that have passed through the object under investigation;
(c) finding areas of the object under investigation with a density of organic materials exceeding a pre-established value, on a basis of a value of X-ray attenuation;
(d) identifying articles contained in the aforementioned found areas of the object under investigation with said density of organic materials higher than the pre-established value, on a basis of an analysis of said recorded X-rays;
(e) selecting among said areas of the object under investigation an area containing an unidentified article;
(f) in case all the articles are identified as not containing a nitrogen-containing explosive having an average density range of 1.25 to 2.00 g/cm3 the process of detecting is stopped;
(g) in case any article is unidentified the method of detecting further comprising;
(h) determining the dimensions and position of said unidentified article in the object under investigation, on a basis of an analysis of said recorded X-rays;
(i) evaluating a mass of a nitrogen-containing explosive being detected based on an average density range of 1.25 to 2.00 g/cm3 which corresponds to said dimensions of the unidentified article;
(k) exposing to thermal neutrons the selected area of the object under investigation containing the unidentified article;
(l) recording, using at least two gamma-ray detectors, gamma-ray quanta with the energy of 10.8 MeV and pairs of simultaneously emitted cascade gamma-ray quanta emitted by said area of the object under investigation exposed to thermal neutrons;
(m) counting pairs of said cascade gamma-ray quanta recorded simultaneously;
(n) determining the overall intensity of gamma rays emitted by the object under investigation;
(o) determining a threshold value for said overall intensity of gamma rays emitted by the object under investigation, on a basis of said evaluated mass of the explosive being detected which corresponds to the dimensions of the unidentified article;
(p) making a decision about presence of a nitrogen-containing explosive having an average density range of 1.25 to 2.00 g/cm3 in the object under investigation in the event that said overall intensity of gamma rays emitted by the object under investigation exceeds the said threshold value.
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Accused Products
Abstract
A method for detecting an explosive in an object under investigation involves the initial X-ray irradiation of the object under investigation, e.g. a piece of luggage or mailing, and forming its X-ray images; using the X-ray images to detect areas with a high density of organic materials and identifying articles therein; determining the location, dimensions and supposed mass of an unidentified article; determining and forming a directional pattern of the neutron radiator corresponding to the dimensions of the unidentified article. The method further includes subsequent thermal neutron irradiation of the area with the unidentified article; recording gamma-ray quanta having the energy of 10.8 MeV and cascade gamma-ray quanta with energies of 5.534 and 5.266 MeV by at least two gamma-ray detectors; counting of simultaneously recorded pairs of cascade gamma-ray quanta; determination of the overall gamma-ray intensity, taking into account weight factors in readings of the detectors; determination of the threshold value for the overall gamma-ray intensity basing on the supposed mass of explosive being detected; and making a decision in the event the threshold value of overall gamma-ray intensity is exceeded. When checking small-size objects, the neutron irradiation step is preceded by replacing the ambient air by a gaseous medium not containing nitrogen.
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Citations
12 Claims
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1. A method for detecting an explosive in an object under investigation, comprising the following steps:
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(a) initially exposing the object under investigation to X-rays for purposes of detecting whether the object contains a nitrogen-containing explosive having an average density range of 1.25 to 2.00 g/cm3;
(b) recording the X-rays that have passed through the object under investigation;
(c) finding areas of the object under investigation with a density of organic materials exceeding a pre-established value, on a basis of a value of X-ray attenuation;
(d) identifying articles contained in the aforementioned found areas of the object under investigation with said density of organic materials higher than the pre-established value, on a basis of an analysis of said recorded X-rays;
(e) selecting among said areas of the object under investigation an area containing an unidentified article;
(f) in case all the articles are identified as not containing a nitrogen-containing explosive having an average density range of 1.25 to 2.00 g/cm3 the process of detecting is stopped;
(g) in case any article is unidentified the method of detecting further comprising;
(h) determining the dimensions and position of said unidentified article in the object under investigation, on a basis of an analysis of said recorded X-rays;
(i) evaluating a mass of a nitrogen-containing explosive being detected based on an average density range of 1.25 to 2.00 g/cm3 which corresponds to said dimensions of the unidentified article;
(k) exposing to thermal neutrons the selected area of the object under investigation containing the unidentified article;
(l) recording, using at least two gamma-ray detectors, gamma-ray quanta with the energy of 10.8 MeV and pairs of simultaneously emitted cascade gamma-ray quanta emitted by said area of the object under investigation exposed to thermal neutrons;
(m) counting pairs of said cascade gamma-ray quanta recorded simultaneously;
(n) determining the overall intensity of gamma rays emitted by the object under investigation;
(o) determining a threshold value for said overall intensity of gamma rays emitted by the object under investigation, on a basis of said evaluated mass of the explosive being detected which corresponds to the dimensions of the unidentified article;
(p) making a decision about presence of a nitrogen-containing explosive having an average density range of 1.25 to 2.00 g/cm3 in the object under investigation in the event that said overall intensity of gamma rays emitted by the object under investigation exceeds the said threshold value. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification