Nuclear-based techniques for the detection of bulk explosives are described. These techniques are shown to provide the only feasible approach for meeting the operational criteria of high throughput of screening luggage and cargo against concealed explosives in air transportation. The nuclear-based techniques are characterized by probing the screened object (e.g. luggage) with highly penetrating radiation, i.e. neutrons or energetic gamma rays. High-energy gamma rays produced by the probing radiation are characteristic to the elemental composition of the objects. The gamma rays are detected by an array of detectors placed near the object. The intensity, energy, and spatial distribution of the detected radiation and their relationship to the primary radiation allow a computer to determine the presence or absence of explosives. The nature of neutron interactions, the gamma detectors used, and the data analysis on which the decision is based are discussed.
展开▼
