A method for detection of explosives based on nuclear resonance absorption of gamma rays in 14N

The physical principles the of Nuclear Resonance Absorption (NRA) method and its application to explosives detection are described. In this method, the object to be tested is scanned by a beam of 9.17 MeV gamma rays which undergoes resonant attenuation whenever the beam encounters regions of nitrogen concentration. This resonant component of attenuation is detected using an array of gamma ray detectors containing a nitrogen-rich medium. From the reconstructed spatial distribution of nitrogen density obtained in multi-view scanning, the presence of an explosive can be determined. ((orig.))