Method for detecting an explosive in an object under investigation

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;
• (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 explosive the process of detecting is stopped;
• (g) in case any article are 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 an explosive being detected which corresponds to said dimensions of the unidentified article;
• (j) determining and forming a directional pattern of a thermal neutron radiator 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 the explosive 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.