A science and profession devoted to the protection of man and his environment from unnecessary radiation exposure. When considering a point source in air, the decrease will follow the inverse square law, which states that the amount of radiation at a given distance from a source is inversely proportional to the square of the distance. The process by which a neutral atom or molecule acquires a positive or negative charge. Any electromagnetic or particulate radiation capable of producing ions, directly or indirectly, in its passage through matter. A neutron is an elementary nuclear particle with a mass slightly larger than a proton and a net charge of zero.
Photons are much more penetrating than alpha and beta particles.
Generally, high density materials are best suited for gamma shielding. Radiation cannot be detected with the unaided senses, an instrument must be used to identify presence, type or intensity of radiation. Some detection systems use the ionization produced in them, and other systems depend upon excitation. Chemical and photographic detection principles are also used. An element is said to be radioactive if it can spontaneously decay or be transformed into another element.