When such forms of particulate matter travel at high velocities, they are regarded as radiation. In short, the two broad classes of radiation are unambiguously differentiated by their speed of propagation and corresponding presence or absence of rest mass.
At one time, electromagnetic rays were thought to be inherently wavelike in character—namely, that they spread out in space and are able to exhibit interference when they come together from two or more sources. Such behaviour is typified by water waves in the way they propagate and periodically reinforce and cancel one another. Matter rays, on the other hand, were considered to be inherently particle-like in character—i.
During the early s, however, major experiments and attendant theories revealed that all forms of radiation, under appropriate conditions, can exhibit both particle-like and wavelike behaviour. This is referred to as the wave—particle duality and provides in large part the foundation for the modern quantum theory of matter and radiation.
The wave behaviour of radiation is apparent in its propagation through space, while the particle behaviour is revealed by the nature of interactions with matter. Because of this, care must be exercised to use the terms waves and particles only when appropriate.
Department of Energy; c Tomihahndorf, Wikimedia Commons. Imagine pulling a nuclide apart as illustrated in Figure All three types of nuclear radiation produce ionization in materials, but they penetrate different distances in materials—that is, they have different ranges. Zanzonico P Positron emission tomography: A review of basic principles, scanner design and performance, and current systems. A mole has 6. The probability of decay is the same no matter when you start counting. When a positron encounters an electron, there is a mutual annihilation in which all the mass of the antielectron-electron pair is converted into pure photon energy.
According to the theory of relativity , the velocity of light is a fixed quantity independent of the velocity of the emitter, the absorber, or a presumably independent observer, all three of which do affect the velocities of common wavelike disturbances such as sound. In an extended definition, the term light embraces the totality of electromagnetic radiation.
The behaviour of light seems to have interested ancient philosophers but without stimulating them to experiment, though all of them were impressed by vision. The first meaningful optical experiments on light were performed by the English physicist and mathematician Isaac Newton beginning in , who showed 1 that white light diffracted by a prism into its various colours can be reconstituted into white light by a prism oppositely arranged and 2 that light of a particular colour selected from the diffracted spectrum of a prism cannot be further diffracted into beams of other colour by an additional prism.
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Physics of Nuclear Radiations: Concepts, Techniques and Applications - CRC Press Book. Physics of Nuclear Radiations: Concepts, Techniques and Applications makes the physics of nuclear radiations accessible to students with a basic background .
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Kluwer Academic, Dordrecht Google Scholar. Zanzonico P Internal radionuclide radiation dosimetry: A review of basic concepts and recent developments. Zanzonio P The intraoperative probe: design, operation, and safety.
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