Ductile Disfunction", "Tin Whiskers" or simply, "WT's"), has been widely used as a "torture" detector at nuclear and DOE sites since the early 1950's. The problem with these devices is that their performance is only a guide. In the case of "WT's" the "fuzzy" results that they provide require extensive interpretation by highly trained personnel using a high tech instrument and an arduous statistical sampling technique. The situation is such that the time and personnel needed for WT testing has cost the nuclear and DOE Industries millions of dollars per year. Thus, the search for a direct and accurate technique which is simple to use and provides results in a matter of a few minutes (or even seconds) has been an ongoing research objective in the field. The results of these research activities have culminated in a new form of "bomb detection". It is called the Atomic Penetrating Radiation (APR) Imaging Technique (patent pending). The APR technique is a method for detecting both nuclear and radioactive sources, directly and simultaneously. The APR technique provides immediate visual feedback to the user which simplifies a nuclear or radioactive site inspection and enhances the detection capability of the human eye. The high resolution is a direct result of the fact that the APR screen is capable of detecting not only the nuclear radiation but also atomic and molecular gases from the area under inspection. One of the most crucial aspects of the imaging technique is the ability to detect sources that do not leave behind a typical atomic or molecular gas cloud, such as those produced by conventional explosives. This has been achieved by the development of a "two part" gas chamber, which is capable of both imaging all of the gases created by nuclear and other radioactive sources and also imaging a wide range of conventional explosives and toxic gases as well. The two parts of the imaging chamber consist of two gas sensors: one capable of detecting the radioactive gases from the nuclear source and the other capable of detecting all the other "weapons" gases. These two sensors are placed in separate compartments of the imaging chamber. As a result, the imaging chamber is capable of detecting both the nuclear and the conventional explosive gases. In addition, the two-part gas chamber also allows the detection of many other gases and vapors such as: halogens, heavy metal vapors, sulfurous fumes, etc. The development of the two-part gas chamber is the result of close cooperation between the government and industry. The imaging chamber was developed using an array of gas sensors by the Navy's Technical Support Center, Weapons System Operational Test and Evaluation in cooperation with Raytheon's Radar Systems Division. The imaging chamber is an extremely simple and economical device. At the current time, when used with an existing explosive detection system such as the PASS (Probability of Antisense Signal), the imaging chamber can increase the detection capability of the system by 1000%. Moreover, with the current state of the art of gas sensor technology, the two-part gas chamber is capable of detecting most all of the conventional explosives used in today's bombs and weapons. Other benefits of this new imaging technique include: very low cost, very little training required to use, very little sample size needed for detection, fast detection time and no need for sample collection or transportation. The use of the two-part imaging chamber with a dual threshold technique allows for the use of a wide variety of sensor arrays. Further, other imaging techniques can be used as well, such as Fourier Transforms. As a result, several unique configurations for detecting conventional explosives are available for the market. These include: (1) a "conventional" detector that uses current state of the art gas sensor technology, (2) a "hybrid" detector that combines the two-part imaging chamber with a neutron detection device and (3) a "universal" detector that combines both the conventional gas sensor technology and also the use of a gas scintillation detection device (gas ionizing agent). These configurations are described further below. (1) The conventional detector uses current state of the art gas sensor technology to detect explosives. This includes the use of a dual threshold technique to distinguish between different types of conventional explosives and conventional explosive threats. The conventional detector can be combined with a wide variety of imaging techniques for detecting the most likely source of an incident, including nuclear and radioactive sources. (2) The hybrid detector uses the two-part imaging chamber with a neutron detection device to distinguish between different types of conventional explosives. In a preferred embodiment, this combination is called the "hybrid" detector. The imaging chamber is used in conjunction with a Geiger-Muller (GM) type neutron detector. The detector system is capable of identifying the "critical components" of the threat; therefore, all components above an alarm level (or set threshold) must be identified to the user as a potentially dangerous situation. The result of the use of the combined system is an effective dual level detection capability; therefore, the detector is not only able to detect the presence of explosive materials, but also be able to positively identify the type of explosive material that has been detected. (3) A universal detector is used in conjunction with a gas scintillation detection device (gas ionizing agent) which makes use of a variety of different methods for detecting gases. The detector is a hybrid detector which also uses the two-part gas chamber for imaging and detection purposes. The use of the dual threshold technique allows for detection of most types of conventional explosives by making use of different types of imaging devices. This detector can also be combined with other imaging techniques to increase its detection capability. The detector is a unique approach, providing the benefits of the universal detector with the performance of a "conventional" detector. This combination can make use of several imaging devices in an array, one imaging device in particular being capable of imaging all types of conventional explosives. In general, the universal detector is an optimum tool for personnel protection at a wide variety of sites in which different types of conventional explosives have been used. (4) The nuclear and radioactive "bomb" sensor, with its unique array of sensors, provides the high resolution capability necessary to identify the exact nature of a potential threat. This is one of the most powerful aspects of the imaging technique as a "nondestructive" explosive detection technique, capable of detecting inanimate materials, including metals, ceramics, plastics and other combustible or explosive materials. The nuclear bomb sensor contains gas sensors capable of detecting "all" types of conventional explosives, as well as other common conventional explosives such as dynamite, TNT, nitroglycerin, etc. The primary embodiment of the two-part gas chamber, as presented in the example of a dual threshold system, is an imaging chamber made from a single housing. The main housing can be aluminum or plastic. The single housing configuration is capable of imaging all types of conventional explosives and thus, it is also the best detector to use for personnel protection at a wide variety of sites in which different types of conventional explosives have been used. However, the dual threshold system, and all the variations described above, can be used on a wide range of possible sensor configurations. The imaging chamber is capable of being made from different configurations in terms of the number and type of sensors used, in order to achieve optimal performance for a particular application. Several embodiments for two-part gas chamber detectors are described below. These embodiments make use of a wide variety of sensor configurations. The single housing configuration is an embodiment which uses a unique approach in order to obtain the advantages of both a nuclear bomb sensor and a two-part imaging chamber. For the detection of conventional explosives, a number of different sensor configurations can be used. One preferred embodiment is a small gas sensor array housed within a metal housing. The metal housing can be made from aluminum or other metal. This particular configuration uses a "dual" threshold detection technique to provide imaging of the most likely source of an incident. The metal housing has a small diameter, and several small gas sensors (such as a "multi-point" sensor) are mounted within the housing. The housing with the gas sensors, along with a few metal disks (each with their own sensor) can be used for imaging purposes. The "critical" portion of a conventional explosive is contained in an extremely thin metal shell, made of metal foil