Patent Number: 060375973
Section: summary

BACKGROUND OF THE INVENTION The present invention relates generally to non-destructive testing, and more specifically to a non-destructive detection system of novel, inexpensive construction utilizing epithermal neutrons and characteristic energies generated by the same upon interacting with an object under study. As further background, a variety of non-destructive detection systems are known for use in applications such as the detection of explosives in luggage or other packages. Current technologies utilized in such detection systems include principles derived from NMR, atomic adsorption, X-ray fluorescence, neutron activation analysis, and X-ray analysis. In addition, a few attempts have been made to utilize CT technology and quadripole moment techniques in such systems. Additional relevant background as to known techniques for non-destructive detection can be found, for instance, in U.S. Pat. Nos: 2,270,373; 2,288,717; 2,297,478; 2,344,043; 3,124,679; 3,146,349; 3,255,352; 3,670,715; 3,832,545; 4,266,132 4,853,550; 4,864,142; 4,882,121; 5,006,299; 5,080,856; 5,098,640; 5,124,554; 5,144,140; 5,153,439; and 5,200,626. Drawbacks of known systems, however, include relatively high construction and operation expense and complexity of the devices utilized both to bombard the sample and receive characteristic signals from an object or sample. The present invention is addressed to the need for a relatively simple, inexpensive device and system which can be utilized to non-destructively interrogate materials, including for example luggage or other packages, and to determine the presence or absence of a given substance in the materials. SUMMARY OF THE INVENTION Accordingly, the invention provides in one preferred embodiment a device for delivering epithermal neutrons, which is a laminate of several polymer layers, e.g. wherein the polymer is high density polyethylene. In particular, the preferred device includes a first polymer layer having embedded therein a source of alpha-radiation, and a second polymer layer which is generally non-permeable or opaque to alpha-radiation and having defined therein a diffraction opening for passing alpha-radiation from the source of alpha-radiation embedded in the first polymer layer. The device further includes a third polymer layer having embedded therein a chemical source of boron, the third polymer layer being positioned relative to the second polymer layer such that alpha-radiation from the source of alpha-radiation impinges upon the source of boron, thereby generating epithermal neutrons. The device further includes a fourth polymer layer which is generally impermeable to the epithermal neutrons and defines a diffraction opening for passing the generated epithermal neutrons. Another embodiment of the invention includes a source/detector array device useful for interrogating an object. In accordance with the invention the array device includes a non-conductive layer such as mylar having affixed thereto an array of self-contained radiation sources selected for thermal neutron sources, infrared radiation sources, and X-ray sources. Also attached to the non-conductive layer in the array are a plurality of signal detectors selected from X-ray detectors, neutron detectors, infrared detectors, and gamma ray detectors. Further, the non-conductive layer includes an imprinted pattern of conductive material electrically connected to the detectors in the array, for transmitting signals generated by the detector, e.g. for immediate analysis or to memory storage for later analysis. Still another preferred embodiment of the invention provides a method for interrogating an object, comprising disposing the object next to an array device such as that described in the paragraph above. The object is bombarded with radiant energy (e.g. x-rays, infrared radiation and/or epithermal neutrons) generated by the self-contained sources, and characteristic radiant signals are generated by the interaction of the radiant energy and the object. The signals can then be analyzed to determine the presence or absence of a predetermined substance in the object. The present invention provides non-destructive detection systems and methods, and component devices useful therein, which are relatively simple in construction and relatively inexpensive in manufacture. Additional objects, features and advantages of the invention will be apparent from the following description.