r so as to provide for a detection completely around the object and with the plurality of successive planes building up a three dimensional profile of the object under inspection. These rings need not all be in the same plane, nor must they be shaped similarly.
The detectors included in the detector arrays of the present invention may include one or more neutron detectors. Such neutron detector(s) are typically separate and may be apart from the C-ring array of gamma ray detectors. Each detector is coupled to appropriate processing circuitry. This processing circuitry may include an artificial neural system (ANS). The ANS allows the signals from each detector to be processed in a parallel distributed processing scheme that provides for a very rapid, yet accurate analysis of the complete data set. In effect, the ANS learns and merges features in the detector observations and automatically generates classification criteria. The ANS has the ability to learn patterns and classify objects based on these patterns. This learning ability is advantageously inherent in the ANS and does not require programming or algorithmic development. The ANS needs only examples from which to learn.
The system of the present invention is further capable of scanning a continuous flow of objects, such as luggage and parcels carried on a conveyor belt. In addition, the operation of the system may be fully automatic so that the system does not depend on operator experience or interpretation, thereby providing for the automatic detection of explosives.
It is a feature of the present invention to provide an explosive detection system that can continuously examine objects for explosive materials at an acceptably high throughput rate, e.g., approximately one object every six seconds.
It is another feature of the invention to provide such a detection system that does not damage film or magnetic recording media.
A further feature of the invention is to provide a detection system that exhibits a high PD at an acceptably low PFA, and that provides an alarm signal indicating the probable presence of an explosive in a particular object prior to the time the object exits the system.
It is yet another feature of the invention to provide an explosive detection system wherein complex and labor-intensive calibration procedures can be minimized, thereby allowing the system to be quickly installed and easily operated.
Still another feature of the invention provides a nitrogen image of the object under investigation. In one embodiment, the spatial resolution of this nitrogen image may be significantly enhanced through the use of X-ray radiography.
A further feature of the invention allows background noise at a specific point in the gamma ray spectrum to be removed, thereby greatly improving the sensitivity of the system to detecting gamma rays at that specific point.
It is another feature of the invention that additional elements, e.g., hydrogen, chlorine, may be identified within the object under investigation, and from that identification improved discrimination of contraband, e.g. explosives or drugs, can be obtained.
Another feature of the invention allows the detection system to learn patterns from examples and classify objects based on these learned patterns, without the need for programming or algorithmic development.
It is still a further feature of the invention to provide a detection system that is readily adaptable to detect a wide variety of different types of explosive or other materials, and/or to quickly correct itself in the event of misclassifying a particular object.
The above and other features and advantages of the present invention will be more apparent from the following description, drawings and appendices wherein:
FIG. 1 is a simplified schematic diagram of a nuclear-based explosive detection system;
FIG. 2A illustrates a perspective view of one embodiment of a luggage and parcel inspection system;
FIG. 2B illustrates the system of FIG. 1 with a shield portion of the system removed;
FIG. 3 illustrates one possible arrangement of a conveyer pat