Method and apparatus for determining a material of a detected item

Abstract

A method for determining the material of a detected item in objects, especially explosives in luggage, using X-ray diffraction. In this method, wherein scatter radiation deflected at the crystal source of the material is measured and compared to characteristic energy spectra or diffraction spectra of the various explosives, the absorption by the material influences the X-ray diffraction spectrum, so that information is missing, and inaccurate conclusions may be drawn regarding the material. To improve this method, the primary beam of an X-ray source is used for measuring the absorption. The beam passes through the material, and, from the absorption, an average atomic number of the material is determined, and this information additionally is used in the comparison to known diffraction spectra. For this purpose, a collimation/detector arrangement preferably has only one collimator (8) and one detector (9), with the collimator (8) having a conically-expanding circular slot (1), which simulates a predetermined angle of the beam path, and a central blind bore (1) opening toward the X-ray source. First and second detectors (13, 14) are disposed in the bore to detect lower and higher X-ray energy, respectively.

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