synchrotron radiation, in physics, electromagnetic radiation emitted by high-speed electrons spiraling along the lines of force of a magnetic field (see magnetism). Depending on the electron's energy and the strength of the magnetic field, the maximum intensity will occur as radio waves, visible light, or X rays. The emission is a consequence of the constant acceleration experienced by the electrons as they move in nearly circular orbits; according to Maxwell's equations, all accelerated charged particles emit electromagnetic radiation. Although predicted much earlier, synchrotron radiation was first observed as a glow associated with protons orbiting in high-energy particle accelerators, such as the synchrotron. In astronomy, synchrotron radiation has been suggested as the mechanism for producing strong celestial radio sources like the Crab Nebula (see radio astronomy). Synchrotron radiation is employed in a host of applications, ranging from solid-state physics to medicine. As excellent producers of X rays, synchrotron sources offer unique probes of the semiconductors that lie at the heart of the electronics industry. Both ultraviolet radiation and X rays generated by synchrotrons are also employed in the treatment of diseases, especially certain forms of skin cancer.

synchrotron: see particle accelerator.

Electromagnetic radiation emitted by charged particles that are moving at speeds close to that of light when their paths are altered. It is so called because it is produced by high-speed particles in a synchrotron. Such radiation is highly polarized (see polarization) and continuous. Its intensity and frequency depend on the strength of the magnetic field that alters the path of the particles, as well as on the energy of those particles. Synchrotron radiation at radio frequencies is emitted by high-energy electrons as they spiral through magnetic fields in space, such as those around Jupiter. Synchrotron radiation is emitted by a variety of astronomical objects, from planets to supernova remnants to quasars.

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Cyclic particle accelerator in which the particle is confined to its orbit by a magnetic field. The strength of the magnetic field increases as the particle's momentum increases. An alternating electric field in synchrony with the orbital frequency of the particle produces acceleration. Synchrotrons are named according to the particles they accelerate. The Tevatron, a proton synchrotron at the Fermi National Accelerator Laboratory in Illinois, U.S., produces the highest particle energies achieved so far.

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