SYNCHROTRON

cyclic particle (electron, proton, heavy-ion) accelerator in which the particle is confined to its orbit by a magnetic field that gradually strengthens as the particle's momentum increases. Acceleration is produced by an alternating electric field that is in synchronism with orbital frequency. The synchrotron is useful when the speed of the particle is near that of light (as in the acceleration of electrons or of protons to extremely high energies), since, under such conditions, speed changes only slowly as the energy changes. Synchrotrons have been developed to accelerate different particles and are named accordingly. Thus, the electron synchrotron accelerates electrons and the proton synchrotron accelerates protons. The highest particle energies ever achieved have been produced with the superconducting proton synchrotron at the Fermi National Accelerator Laboratory, Batavia, Ill., U.S., which reaches 1 TeV (1 trillion electron volts). The highest-energy electron synchrotron is at CERN in Geneva; it reaches 50 GeV (50 billion electron volts).