, a synchrotron collider
type particle accelerator at fermi national accelerator laboratory
(fermilab), batavia, illinois, usa. shut down in 2011, until 2007 it was the most powerful particle accelerator in the world, accelerating protons to an energy of over 1 tev
(tera electron volts). beams of circulating protons in the two circular vacuum chambers in the two rings visible collided at their intersection point.
animation showing the operation of a linear accelerator
, widely used in both physics research and cancer treatment.
a particle accelerator is a machine that uses electromagnetic fields to propel charged particles to very high speeds and energies, and to contain them in well-defined beams.
large accelerators are used for basic research in particle physics. the largest accelerator currently operating is the large hadron collider (lhc) near geneva, switzerland, operated by the cern. it is a collider accelerator, which can accelerate two beams of protons to an energy of 6.5 tev and cause them to collide head-on, creating center-of-mass energies of 13 tev. other powerful accelerators are kekb at kek in japan, rhic at brookhaven national laboratory in new york and, formerly, the tevatron at fermilab, batavia, illinois. accelerators are also used 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 the target of the particle beams of early accelerators was usually the atoms of a piece of matter, with the goal being to create collisions with their nuclei in order to investigate nuclear structure, accelerators were commonly referred to as atom smashers in the 20th century. the term persists despite the fact that many modern accelerators create collisions between two subatomic particles, rather than a particle and an atomic nucleus.