The present system relates to a system for detecting explosives concealed in an object or container, such as luggage, by selective detonation of the concealed explosive with a focused energy source. There has been an increased interest in devices for detecting explosives in, for example, airline luggage. This interest has been accelerated by the terrorist activity marked by Sep. 11, 2001. Many of these devices employ various types of radiation, which is absorbed or emitted in the presence of an explosive substance or device to leave a “foot print” on a detector. This is the concept of, for example, X-Ray.
The threat is amplified when charges are used to disperse chemical and biological agents upon detonation. This method of dispersal not only injures personnel and destroys property in the blast zone, but disperses secondary biological or biochemical agents. Dispersal in this manner makes detection and cleanup very difficult and allows a small devise to radiate biochemically active matter through a wide area.
In order to be effective, the method of detection of the explosive threat to aviation, mails, or shipping requires detection techniques that are highly sensitive, specific, rapid and non-intrusive. In the case of biological and chemical agents it also requires containment. The problem with the previous detection methods for the scanning of luggage, baggage and other parcels for explosive material contained or concealed within their confines is the time and inaccuracy of the process. For example, approximately two million pieces of luggage are checked and/or carried onto aircraft daily by over seven hundred and fifty thousand passengers at over six hundred airports in this country alone. Many more billions of parcels move through the mails, transportation companies and the like. Many of these parcels are destined for sensitive destinations.
The problem, thus, becomes the screening of a large number of items in a way that is efficient and effective. Because of the sheer number, screening all parcels is impractical, but those that have the potential of doing substantial harm can be isolated. Nevertheless, a secure, cost and time efficient system that has a very high probability of success is required.
Thus, the desired system to scan the luggage and parcels to detect the presence of any explosive material is not easily achieved. Prior art detection devices which “scan” the investigated object, like X-Ray, are the most common. This method relies on a trained operator to visually inspect the X-Ray image to determine the presence of explosives. The problem with this system is obvious. While guns and knives lend themselves to this type of detection, explosives such as C-4, hidden in, for example, soap, do not.
Another method of detection involves a radiated system for the detection of nitrogen, which is generally present in the explosive materials to be detected. The object under observation is positioned within a cavity structure and subjected to a bombardment of thermal neutrons. The thermal neutrons interact with any nitrogen contained in the object to induce the emission of gamma rays at an energy level characteristic of the nitrogen element. In general, prior art systems have not met the desired characteristics of having a high probability of detection with a low probability of false alarms at acceptable throughput rates.
A nuclear detection technique can provide for the detection of the nitrogen content to reliably indicate the presence of large nitrogen content. However, the frequent occurrence of nitrogen in non-explosive materials limits the level of detection sensitivity and merely detecting the presence or absence of nitrogen alone is not sufficient. Therefore, additional information is required beyond simply sensing the presence of the nitrogen. This vastly complicates such systems and increases the probability of false positives.
Although the efficient detection of nitrogen may be viable, to be effective, the detection of nitrogen must be able to give the maximum information of the physical parameters of the explosive, such as density and spatial distribution. The use of nuclear based techniques which subject the luggage or parcels to thermal neutrons has not, to-date, been effective in providing this information. It is important that the intensity, energy and spatial distribution of the detected radiations from the object under observation be provided in such a way so as to help to determine the presence or absence of explosives, and this has not yet been accomplished. This leads to a high number of false positives.
In addition to the nuclear based systems described above, non-nuclear systems have also been investigated. These systems have achieved relatively high efficiencies of detection, but generally have relatively high false alarm rates and have long screening times. These types of non-nuclear systems, therefore, by themselves cannot achieve the desired results. It is possible to combine a non-nuclear system with a nuclear system, but the effectiveness does not improve.
Other types of prior art explosive detection systems depend upon the prior seeding of explosive materials with a tracer material, such as a radioactive tracer. Although this type of system could be very useful if all explosive material were manufactured with such tracer material, because of the large amount of explosive material which has already been manufactured and because of the difficulty of controlling the manufacture of all explosive material so that they contain such tracer material, this type of system is not practical.
Ideally, a detection system must be able to detect the presence of explosive material of a conventional type and of an unconventional type, whether disposed within an object either in its original manufactured form, or if deployed within the object so as to attempt to confuse or evade the detection system. The prior art systems have not met these various criteria and cannot produce the desired high probability of detection with the relatively low production of false alarms.
In addition to high detection sensitivity and low false alarm, the detection of the explosive should be independent of the specific configuration and must be non-intrusive in order to protect privacy. The detection equipment, of course, must be non-hazardous to the contents of the checked items and to the operating personnel and environment. Other more general criteria are that the system must be reliable, easily maintained and operable by relatively unskilled personnel and that the cost must be low enough so as to be non-burdensome to airlines and airports. Finally, it is desirable, when all other requirements achieved that the size of the system be relatively small so that the system may be useful in a wide variety of environments.
Explosives, as a general rule, are by their very nature unstable compounds. Most are nitro-derivatives, which are set off by exciting molecules within the substance causing a chain, non-nuclear, chemical, exothermic reaction. Because of the fragile structure of an airplane, it does not take a substantial amount of an explosive material, properly placed, to destroy the aerodynamic characteristics of the plane. As set forth above, the prior art detection devices, which use, for example, X-Ray, Gamma-Ray, and the like, may be adequate for detecting naked explosive substances, they have been found inadequate where these substances are incased in materials such as soap, or the like, and then packed in large cases amongst other personal items, such as clothing. Thus, the only fool proof way of detecting the presence of these explosives is to detonate them prior to placing the case, or other object, onboard, for example, an airplane.
It is well known that explosives are substantially less stable than other compositions or compounds normally found within a container such as a parcel, baggage, brief case, or the like. Although, this is generally true, many explosives, such as C-4, are relatively immune to, for example, shock, pressure, and the like. However, these explosives require some sort of a detonator to trigger or activate the main charge. Thus, while particular explosive may not be sensitive to shock or heat, they do require a detonator which is much more sensitive to these conditions. Therefore, a bomb, charge, or explosive, designed to be detonated at a particular time or location, such as in a flying airplane, requires a detonator or triggering device to initiate the detonation of the primary charge. Therefore, an acceptable detection system need only provide sufficient energy to trigger the detonator.
Unfortunately, most prior art detonation systems do not focus the detonation energy on the container so that the least amount of energy can be effective in reaching the critical criteria in the shortest amount of time. Because of the myriad of parcel shapes and sizes, most inspection chambers do not provide for an intensity of directed energy. This failure requires long exposure times and/or a failed detonation of the contained explosive.
It would, therefore, be desirous to have a system for detection of explosives within a container which employs a minimum amount of examination time, and assures the greatest probability of focusing an effective amount of detonating energy on the contained explosive, irrespective of the nature, shape or composition of the explosive. It would also be desirous to have a secure system which would not only contain the ensuing blast, but neutralize or contain dispersed chemical or biochemical agents.
It will be realized that the foregoing discussion and examples of the related art and the scope of the illustrations related thereto are set forth as background only. Their intent is to be exemplary and illustrative of problems related to the art, as well as prior attempts to address these problems at least in part. They are not, nor are they intended to be exclusive or exhaustive. Nor are they intended, in any manner, to be read as a limitation of the instant disclosure or the appended claims.