What is "particle accelerator"

Particle accelerator \Par"ti*cle ac*cel"er*a*tor\, n. (Physics) A large and expensive scientific instrument used by physicists to accelerate elementary particles (such as protons or electrons) to speeds near that of light, for the purpose of investigating the fundamental properties of matter; sometimes also called an atom smasher, since the particles thus accelerated are often directed at targets of atoms which are fragmented by the impact into their more fundamental component particles.

Note: The particles generated by impact of a beam in an accelerator on its target are detected by various types of detecting apparatus, and procedures are required to sort and identify the many particles created. The fundamental particles generated by impacts in a particle accelerator are often those not actually present inside atoms; and in certain types of particle accelerator, such as the colliding beam accelerator, the impact which generates energetic particles is with other fundamental particles, and not with atoms.

n. A device that accelerates electrically charged particles to extremely high speeds, for the purpose of inducing high energy reactions or producing high energy radiation.

n. a scientific instrument that increases the kinetic energy of charged particles [syn: accelerator, atom smasher]

A particle accelerator is a machine that uses electromagnetic fields to propel charged particles to nearly light speed and to contain them in well-defined beams. Large accelerators are used in particle physics as colliders (e.g. the LHC at CERN, KEKB at KEK in Japan, RHIC at Brookhaven National Laboratory, and Tevatron at Fermilab), or as synchrotron light sources for the study of condensed matter physics. Smaller particle accelerators are used in a wide variety of applications, including particle therapy for oncological purposes, radioisotope production for medical diagnostics, ion implanters for manufacture of semiconductors, and accelerator mass spectrometers for measurements of rare isotopes such as radiocarbon. There are currently more than 30,000 accelerators in operation around the world.

There are two basic classes of accelerators: electrostatic and electrodynamic (or electromagnetic) accelerators. Electrostatic accelerators use static electric fields to accelerate particles. The most common types are the Cockcroft–Walton generator and the Van de Graaff generator. A small-scale example of this class is the cathode ray tube in an ordinary old television set. The achievable kinetic energy for particles in these devices is determined by the accelerating voltage, which is limited by electrical breakdown. Electrodynamic or electromagnetic accelerators, on the other hand, use changing electromagnetic fields (either magnetic induction or oscillating radio frequency fields) to accelerate particles. Since in these types the particles can pass through the same accelerating field multiple times, the output energy is not limited by the strength of the accelerating field. This class, which was first developed in the 1920s, is the basis for most modern large-scale accelerators.

Rolf Widerøe, Gustav Ising, Leó Szilárd, Max Steenbeck, and Ernest Lawrence are considered pioneers of this field, conceiving and building the first operational linear particle accelerator, the betatron, and the cyclotron.

Because colliders can give evidence of the structure of the subatomic world, accelerators were commonly referred to as atom smashers in the 20th century. Despite the fact that most accelerators (but not ion facilities) actually propel subatomic particles, the term persists in popular usage when referring to particle accelerators in general.