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...Colors. To measure this tiny quantity-less than a millionth of the energy needed to split the nucleus of an atom-the scientists devised an ingenious technique. Light from a 200-watt mercury vapor lamp was focused on a diffraction grating, which, like a prism, broke up the beam into its constituent rainbow of colors, its separate wave lengths of light. By rotating the grating to a carefully calculated angle, the scientists were able to reflect light of a single, specific wave length at a target. Knowing the wave length, they were able to determine precisely the energy...
Beginning with the light of shortest wave length (and thus the highest energy), they aimed a beam from the grating through a Pyrex cylinder containing hydrogen and deuterium iodide gas, which breaks down when exposed to light. When molecules of deuterium iodide were struck by photons in the light beam, they split into fast-moving atoms of deuterium and sluggish, heavier atoms of iodine. Some of the speeding deuterium atoms in turn collided with hydrogen molecules in the cylinder, knocking off one of the hydrogen atoms and combining with the other to form deuterium hydride...
Newtonian or Quantum? After exposing the cylinder to light of a uniform wave length for periods ranging from half an hour to ten hours, the scientists analyzed its contents to detect molecules of deuterium hydride. The process was repeated, each time with a light beam of longer wave length and lower energy, until they failed to find molecules of deuterium hydride in the cylinder-no matter how long the gases had been exposed to the light. At this particular wave length, it seemed clear, the deuterium atoms had not been given enough velocity to split the hydrogen molecules and combine...
Silver atoms that are caught in the penetrating beam capture neutrons and briefly become unstable isotopes, emitting gamma rays that can be recorded by the snooper's scintillation counter. Since silver isotopes, like radioactive atoms of other elements, have their own characteristic half life-or rate of decay-and emit gamma rays at a specific energy level, the snooper's detectors can distinguish them from atoms of other elements in the area that have also been made radioactive by the neutron beam...
...power to produce the snooper's stream of neutrons comes from a simple gasoline engine that runs a primitive type of particle accelerator. A beam of deuterium (or heavy hydrogen) particles emitted by the generator is directed against deuterium absorbed in a titanium target. As the deuterium particles collide, they release neutrons that are channeled into a beam that can cover a two-square-foot area of ground. The entire device, including the recording instruments, is small and light enough to be carried in the back of a Jeep. It has already been given trials in the field...