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Encyclopedia > Particle accelerator
A 1960s single stage 2 MeV linear Van de Graaff accelerator, here opened for maintenance
A 1960s single stage 2 MeV linear Van de Graaff accelerator, here opened for maintenance

A particle accelerator (or atom smasher[1]) is a device that uses electric fields to propel electrically-charged particles to high speeds and to contain them. An ordinary CRT television set is a simple form of accelerator. There are two basic types: linear accelerators and circular accelerators. Download high resolution version (1222x913, 118 KB)1960s vintage 2MeV High Voltage vandergraff linear accelerator. ... Download high resolution version (1222x913, 118 KB)1960s vintage 2MeV High Voltage vandergraff linear accelerator. ... In physics, the space surrounding an electric charge or in the presence of a time-varying magnetic field has a property called an electric field. ... This box:      Electric charge is a fundamental conserved property of some subatomic particles, which determines their electromagnetic interaction. ... For the novel, see The Elementary Particles. ... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ...


This page describes types of particle accelerators. For a list of existing and historic particle accelerators see: List of accelerators in particle physics. A list of particle accelerators used for particle physics experiments. ...

Contents

Uses of particle accelerators

Beams of high-energy particles are useful for both fundamental and applied research in the sciences. For the most basic inquiries into the dynamics and structure of matter, space, and time, physicists seek the simplest kinds of interactions at the highest possible energies. These typically entail particle energies of many GeV or more, and the interactions of the simplest kinds of particles: leptons (e.g. electrons and positrons) and quarks for the matter, or photons and gluons for the field quanta. Since isolated quarks are experimentally unavailable due to color confinement, the simplest available experiments involve the interactions of, first, leptons with each other, and second, of leptons with nucleons, which are composed of quarks and gluons. To study the collisions of quarks with each other, we resort to collisions of nucleons, which at high energy may be usefully considered as essentially 2-body interactions of the quarks and gluons of which they are composed. Thus elementary particle physicists tend to use machines creating beams of electrons, positrons, protons, and anti-protons, interacting with each other or with the simplest nuclei (eg, hydrogen or deuterium) at the highest possible energies, generally hundreds of GeV or more. A GEV (or Ground Effect Vehicle) is vehicle that takes advantage of the aerodynamic principle of ground effect (or Wing-in-ground). ... In physics, a lepton is a particle with spin-1/2 (a fermion) that does not experience the strong interaction (that is, the strong nuclear force). ... The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ... For other uses, see Quark (disambiguation). ... In modern physics the photon is the elementary particle responsible for electromagnetic phenomena. ... In particle physics, gluons are subatomic particles that cause quarks to interact, and are indirectly responsible for the binding of protons and neutrons together in atomic nuclei. ... Quantum field theory (QFT) is the quantum theory of fields. ... Colour confinement (often just confinement) is the physics phenomenon that color charged particles (such as quarks) cannot be isolated. ... In physics a nucleon is a collective name for two baryons: the neutron and the proton. ... In particle physics, the parton was a hypothetical fundamental particle considered, in the parton model of strong interactions, to be a constituent of the hadron. ... The antiproton is the antiparticle of the proton. ... Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen (~154 PPM). ...


At a higher level of complexity, nuclear physicists and cosmologists may use beams of bare atomic nuclei, stripped of electrons, to investigate the structure, interactions, and properties of the nuclei themselves, and of condensed matter at extremely high temperatures and densities, such as might have occurred in the first moments of the Big Bang. These investigations often involve collisions of heavy nuclei--of atoms like iron or gold--at energies of several GeV per nucleon. At lower energies, beams of accelerated nuclei are also used in medicine, as for the treatment of cancer. Nuclear physics is the branch of physics concerned with the nucleus of the atom. ... Cosmology is the study of the large-scale structure and history of the universe. ... The nucleus of an atom is the very small dense region, of positive charge, in its centre consisting of nucleons (protons and neutrons). ... It has been suggested that Solid state physics be merged into this article or section. ... For other uses, see Big Bang (disambiguation). ... In physics a nucleon is a collective name for two baryons: the neutron and the proton. ...


Besides being of fundamental interest, high energy electrons may be coaxed into emitting extremely bright and coherent beams of high energy photons--ultraviolet and X ray--via synchrotron radiation, which photons have numerous uses in the study of atomic structure, chemistry, condensed matter physics, biology, and technology. Examples include the ESRF in Europe, which has recently been used to extract detailed three - dimensional images of insects trapped in amber [2] Thus there is a great demand for electron accelerators of moderate (GeV) energy and high intensity. General Electric synchrotron accelerator built in 1946, the origin of the discovery of synchrotron radiation. ... ESRF site ESRF redirects here, for the medical condition, see end stage renal failure The European Synchrotron Radiation Facility is a joint research facility supported by 18 European countries situated in Grenoble, France. ...


High-energy machines

Beam lines leading from the Van de Graaf accelerator to various experiments, in the basement of the Jussieu Campus in Paris
Beam lines leading from the Van de Graaf accelerator to various experiments, in the basement of the Jussieu Campus in Paris

Linear high-energy accelerators use a linear array of plates (or drift tubes) to which an alternating high-energy field is applied. As the particles approach a plate they are accelerated towards it by an opposite polarity charge applied to the plate. As they pass through a hole in the plate, the polarity is switched so that the plate now repels them and they are now accelerated by it towards the next plate. Normally a stream of "bunches" of particles are accelerated, so a carefully controlled AC voltage is applied to each plate to continuously repeat this process for each bunch. Download high resolution version (2592x1676, 868 KB)Experimental lines of particle accelerator in the basement of the Jussieu Campus in Paris Copyright © 2004 David Monniaux File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Download high resolution version (2592x1676, 868 KB)Experimental lines of particle accelerator in the basement of the Jussieu Campus in Paris Copyright © 2004 David Monniaux File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... Main entrance Gridiron bars The Jussieu Campus (Campus Universitaire de Jussieu) is a higher education campus located in the 5th arrondissement of Paris, France. ... This article is about the capital of France. ...

In early particle accelerators a Cockcroft-Walton voltage multiplier was responsible for voltage multiplying. This piece of the accelerator helped in the development of the atomic bomb. Built in 1937 by Philips of Eindhoven it currently resides in the National Science Museum in London, England.
In early particle accelerators a Cockcroft-Walton voltage multiplier was responsible for voltage multiplying. This piece of the accelerator helped in the development of the atomic bomb. Built in 1937 by Philips of Eindhoven it currently resides in the National Science Museum in London, England.

As the particles approach the speed of light the switching rate of the electric fields becomes so high that they operate at microwave frequencies, and so RF cavity resonators are used in higher energy machines instead of simple plates. Image File history File links Download high resolution version (960x1280, 143 KB) photo by Alkivar In early particle accelerators a Cockcroft-Walton voltage multiplier was responsible for voltage multiplying. ... Image File history File links Download high resolution version (960x1280, 143 KB) photo by Alkivar In early particle accelerators a Cockcroft-Walton voltage multiplier was responsible for voltage multiplying. ... The Cockcroft-Walton (CW) generator, or multiplier, was named after the two men who in 1932 used this circuit design to power their particle accelerator, performing the first artificial nuclear disintegration in history. ... The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 kilometers (11 mi) above the hypocenter A nuclear weapon derives its destructive force from nuclear reactions of fusion or fission. ... Philips HQ in Amsterdam Koninklijke Philips Electronics N.V. (Royal Philips Electronics N.V.), usually known as Philips, (Euronext: PHIA, NYSE: PHG) is one of the largest electronics companies in the world, founded and headquartered in the Netherlands. ... Country Province Government  - Mayor G.Braks (CDA) Area (2006)  - Municipality 88. ... The Science Museum on Exhibition Road, South Kensington, London is part of the National Museum of Science and Industry. ... This article is about the capital of England and the United Kingdom. ... For other uses, see England (disambiguation). ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


DC accelerator types capable of accelerating particles to speeds sufficient to cause nuclear reactions are Cockcroft-Walton generators or voltage multipliers, which convert AC to high voltage DC, or Van de Graaff generators that use static electricity carried by belts. The Cockcroft-Walton (CW) generator, or multiplier, was named after the two men who in 1932 used this circuit design to power their particle accelerator, performing the first artificial nuclear disintegration in history. ... Villard cascade voltage multiplier. ... Van de Graf generator. ...


The largest and most powerful particle accelerators, such as the RHIC, the LHC (scheduled to start operation in 2008) and the Tevatron, are used for experimental particle physics. Particle accelerators can also produce proton beams, which can produce "proton-heavy" medical or research isotopes as opposed to the "neutron-heavy" ones made in fission reactors. An example of this type of machine is LANSCE at Los Alamos. The Relativistic Heavy Ion Collider (RHIC) is a heavy-ion collider located at and operated by the Brookhaven National Laboratory in Upton, New York. ... , The Large Hadron Collider (LHC) is a particle accelerator and Hadron collider located at CERN, near Geneva, Switzerland. ... Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... In the scientific method, an experiment (Latin: ex- periri, of (or from) trying) is a set of observations performed in the context of solving a particular problem or question, to retain or falsify a hypothesis or research concerning phenomena. ... Thousands of particles explode from the collision point of two relativistic (100 GeV per nucleon) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... For other uses, see Isotope (disambiguation). ... Los Alamos National Laboratory, aerial view from 1995. ...


Low-energy machines

Everyday examples of particle accelerators are those found in television sets and X-ray generators. Low-energy accelerators such as cathode ray tubes and X-ray generators use a single pair of electrodes with a DC voltage of a few thousand volts between them. In an X-ray generator, the target itself is one of the electrodes. A low-energy particle accelerator called an ion implanter is used in the manufacture of integrated circuits. In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz... For other uses, see Electrode (disambiguation). ... Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ... Ion implantation is a materials engineering process by which ions of a material can be implanted into another solid, thereby changing the physical properties of the solid. ... Integrated circuit of Atmel Diopsis 740 System on Chip showing memory blocks, logic and input/output pads around the periphery Microchips with a transparent window, showing the integrated circuit inside. ...


Linear particle accelerators

Main article: Linear particle accelerator

In a linear accelerator (linac), particles are accelerated in a straight line with a target of interest at one end. Linacs are very widely used - every cathode ray tube contains one. They are also used to provide an initial low-energy kick to particles before they are injected into circular accelerators. The longest linac in the world is the Stanford Linear Accelerator, SLAC, which is 3 km (2 miles) long. SLAC is an electron-positron collider. Linear accelerator (LINAC) used for medical radiation therapy; example made by Siemens AG. A linear particle accelerator (also called a LINAC) is an electrical device for the acceleration of subatomic particles. ... Cathode ray tube employing electromagnetic focus and deflection Cutaway rendering of a color CRT: 1. ... The Stanford Linear Accelerator Center (SLAC) is a United States Department of Energy National Laboratory operated by Stanford University under the programmatic direction of the U.S. Department of Energy Office of Science. ... The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ...

The now disused Koffler particle accelerator at the Weitzmann Institute, one of Israel's most accomplished institutions of higher learning in the sciences.
The now disused Koffler particle accelerator at the Weitzmann Institute, one of Israel's most accomplished institutions of higher learning in the sciences.

Linear accelerators are also widely used in medicine, for radiotherapy and radiosurgery. Medical grade LINACs accelerate electrons using a klystron and a complex bending magnet arrangement which produces a beam of 6-30 million electron-volt (MeV) energy. The electrons can be used directly or they can be collided with a target to produce a beam of X-rays. The reliability, flexibility and accuracy of the radiation beam produced has largely supplanted the older use of Cobalt-60 therapy as a treatment tool. Radiation therapy (or radiotherapy) is the medical use of ionizing radiation as part of cancer treatment to control malignant cells (not to be confused with radiology, the use of radiation in medical imaging and diagnosis). ... Radiosurgery is a medical procedure which allows non-invasive brain surgery, i. ... Reflex klystron Type 2K25 or 723 A/B. The threaded adjustment rod on the right side allows the position of the reflector to be adjusted (by compressing the reflex cavity), and thus the natural resonant frequency of the device. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... An X-ray picture (radiograph), taken by Wilhelm Röntgen in 1896, of his wife, Anna Bertha Ludwigs[1] hand X-rays (or Röntgen rays) are a form of electromagnetic radiation with a wavelength in the range of 10 to 0. ... Cobalt 60 is a Front 242 side project featuring Front 242s Jean-Luc de Meyer and Dominique Lallement. ...


Tandem electrostatic accelerators

In a tandem accelerator, the negatively charged ion gains energy by attraction to the very high positive voltage at the geometric centre of the pressure vessel. When it arrives at the centre region known as the high voltage terminal, some electrons are stripped from the ion. The ion then becomes positive and accelerated away by the high positive voltage. Thus, this type of accelerator is called a 'tandem' accelerator. The accelerator has two stages of acceleration, first pulling and then pushing the charged particles. An example of a tandem accelerator is ANTARES (Australian National Tandem Accelerator for Applied Research). This article is about a particle accelerator. ...


Circular or cyclic accelerators

In the circular accelerator, particles move in a circle until they reach sufficient energy. The particle track is typically bent into a circle using electromagnets. The advantage of circular accelerators over linear accelerators (linacs) is that the ring topology allows continuous acceleration, as the particle can transit indefinitely. Another advantage is that a circular accelerator is relatively smaller than a linear accelerator of comparable power (i.e. a linac would have to be extremely long to have the equivalent power of a circular accelerator). An electromagnet is a type of magnet in which the magnetic field is produced by the flow of an electric current. ...


Depending on the energy and the particle being accelerated, circular accelerators suffer a disadvantage in that the particles emit synchrotron radiation. When any charged particle is accelerated, it emits electromagnetic radiation and secondary emissions. As a particle traveling in a circle is always accelerating towards the center of the circle, it continuously radiates towards the tangent of the circle. This radiation is called synchrotron light and depends highly on the mass of the accelerating particle. For this reason, many high energy electron accelerators are linacs. Certain accelerators (synchrotrons) are however built specially for producing synchtrotron light (X-rays). General Electric synchrotron accelerator built in 1946, the origin of the discovery of synchrotron radiation. ... This box:      Electromagnetic (EM) radiation is a self-propagating wave in space with electric and magnetic components. ... Secondary emission is a phenomenon that occurs in electron tubes where electrons impact an electrode with sufficient energy to knock additional electrons from the surface of that electrode. ... Synchrotron radiation emerging from a beam port. ... Synchrotrons are now mostly used for producing monochromatic high intensity X-ray beams; here, the synchrotron is the circular track, off which the beamlines branch. ... In the NATO phonetic alphabet, X-ray represents the letter X. An X-ray picture (radiograph) taken by Röntgen An X-ray is a form of electromagnetic radiation with a wavelength approximately in the range of 5 pm to 10 nanometers (corresponding to frequencies in the range 30 PHz...


Since the special theory of relativity requires that matter always travels slower than the speed of light in a vacuum, in high-energy accelerators, as the energy increases the particle speed approaches the speed of light as a limit, never quite attained. Therefore particle physicists do not generally think in terms of speed, but rather in terms of a particle's energy or momentum, usually measured in electron volts (eV). An important principle for circular accelerators, and particle beams in general, is that the curvature of the particle trajectory is proportional to the particle charge and to the magnetic field, but inversely proportional to the (typically relativistic) momentum. Special relativity (SR) or the special theory of relativity is the physical theory published in 1905 by Albert Einstein. ... Look up Vacuum in Wiktionary, the free dictionary. ... This article is about momentum in physics. ... An electronvolt (symbol: eV) is the amount of energy gained by a single unbound electron when it falls through an electrostatic potential difference of one volt. ... A particle beam is an accelerated stream of charged particles or atoms (often moving at very near the speed of light) which may be directed by magnets and focused by electrostatic lenses, although they may also be self-focusing (see Pinch). ... In mathematics, curvature refers to any of a number of loosely related concepts in different areas of geometry. ... For a less technical and generally accessible introduction to the topic, see Introduction to special relativity. ... This article is about momentum in physics. ...


Cyclotrons

The earliest circular accelerators were cyclotrons, invented in 1929 by Ernest O. Lawrence at the University of California, Berkeley. Cyclotrons have a single pair of hollow 'D'-shaped plates to accelerate the particles and a single large dipole magnet to bend their path into a circular orbit. It is a characteristic property of charged particles in a uniform and constant magnetic field B that they orbit with a constant period, at a frequency called the cyclotron frequency, so long as their speed is small compared to the speed of light c. This means that the accelerating D's of a cyclotron can be driven at a constant frequency by a radio frequency (RF) accelerating power source, as the beam spirals outwards continuously. The particles are injected in the centre of the magnet and are extracted at the outer edge at their maximum energy. A pair of Dee electrodes with loops of coolant pipes on their surface at the Lawrence Hall of Science. ... Ernest Orlando Lawrence (August 8, 1901 - August 27, 1958) was an American physicist and Nobel laureate best known for his invention of the cyclotron. ... Sather Tower (the Campanile) looking out over the San Francisco Bay and Mount Tamalpais. ... A dipole magnet, in particle accelerators, is a magnet constructed to create a homogeneous magnetic field over some distance. ... The gyroradius (also known as radius of gyration, Larmor radius or cyclotron radius) defines the radius of the circular motion of a charged particle in the presence of a uniform magnetic field. ...


Cyclotrons reach an energy limit because of relativistic effects whereby the particles effectively become more massive, so that their cyclotron frequency drops out of synch with the accelerating RF. Therefore simple cyclotrons can accelerate protons only to an energy of around 15 million electron volts (15 MeV, corresponding to a speed of roughly 10% of c), because the protons get out of phase with the driving electric field. If accelerated further, the beam would continue to spiral outward to a larger radius but the particles would no longer gain enough speed to complete the larger circle in step with the accelerating RF. Cyclotrons are nevertheless still useful for lower energy applications. The term mass in special relativity can be used in different ways, occasionally leading to confusion. ...


Synchrocyclotrons and isochronous cyclotrons

Main article: Synchrocyclotron

There are ways of modifying the classic cyclotron to increase the energy limit. This may be done in a continuous beam, constant frequency, machine by shaping the magnet poles so to increase magnetic field with radius. Then higher energy particles travel a shorter distance in each orbit than they otherwise would, and can remain in phase with the accelerating field. Such machines are called isochronous cyclotrons. Their advantage is that they can deliver continuous beams of higher average intensity, which is useful for some applications. The main disadvantages are the size and cost of the large magnet needed, and the difficulty in achieving the higher field required at the outer edge. A part of a magnet from the Orsay synchrocyclotron, now used by the proton therapy center (to be replaced in 2008 by newer technologies) A synchrocyclotron is a cyclotron in which the frequency of the driving RF electric field is varied to compensate for the mass gain of the accelerated...


Another possibility, the synchrocyclotron, accelerates the particles in bunches, in a constant B field, but reduces the RF accelerating field's frequency so as to keep the particles in step as they spiral outward. This approach suffers from low average beam intensity due to the bunching, and again from the need for a huge magnet of large radius and constant field over the larger orbit demanded by high energy.

A magnet in the synchrocyclotron at the Orsay proton therapy center
A magnet in the synchrocyclotron at the Orsay proton therapy center

ImageMetadata File history File links Download high resolution version (2592x1944, 2060 KB) Magnet of the synchrocyclotron at the Orsay proton therapy center Copyright © 2005 David Monniaux File links The following pages link to this file: Particle accelerator ... ImageMetadata File history File links Download high resolution version (2592x1944, 2060 KB) Magnet of the synchrocyclotron at the Orsay proton therapy center Copyright © 2005 David Monniaux File links The following pages link to this file: Particle accelerator ... Orsay is a commune of Essonne, Île-de-France located in the southwestern suburbs of Paris, France. ... Proton therapy is a kind of external beam radiotherapy where protons are directed to a tumor site. ...

Betatrons

Main article: Betatron

Another type of circular accelerator, invented in 1940 for accelerating electrons, is the Betatron. These machines, like synchrotrons, use a donut-shaped ring magnet (see below) with a cyclically increasing B field, but accelerate the particles by induction from the increasing magnetic field, as if they were the secondary winding in a transformer, due to the changing magnetic flux through the orbit. Achieving constant orbital radius while supplying the proper accelerating electric field requires that the magnetic flux linking the orbit be somewhat independent of the magnetic field on the orbit, bending the particles into a constant radius curve. These machines have in practice been limited by the large radiative losses suffered by the electrons moving at nearly the speed of light in a relatively small radius orbit. A betatron is a particle accelerator developed by Donald Kerst at the University of Illinois in 1940 to accelerate electrons. ... For other uses, see Electron (disambiguation). ... A betatron is a particle accelerator developed by Donald Kerst at the University of Illinois in 1940 to accelerate electrons. ...


Synchrotrons

Main article: Synchrotron

To reach still higher energies, with relativistic mass approaching or exceeding the rest mass of the particles (for protons, billions of electron volts GeV), it is necessary to use a synchrotron. This is an accelerator in which the particles are accelerated in a ring of constant radius. An immediate advantage over cyclotrons is that the magnetic field need only be present over the actual region of the particle orbits, which is very much narrower than the diameter of the ring. (The largest cyclotron built in the US had a 184 in dia magnet pole, whereas the diameter of the LEP and LHC is nearly 10 km. The aperture of the beam of the latter was of the order of centimeters.) Synchrotrons are now mostly used for producing monochromatic high intensity X-ray beams; here, the synchrotron is the circular track, off which the beamlines branch. ... A GEV (or Ground Effect Vehicle) is vehicle that takes advantage of the aerodynamic principle of ground effect (or Wing-in-ground). ... Synchrotrons are now mostly used for producing monochromatic high intensity X-ray beams; here, the synchrotron is the circular track, off which the beamlines branch. ... The Large Electron-Positron Collider (usually called LEP for short. ... , The Large Hadron Collider (LHC) is a particle accelerator and Hadron collider located at CERN, near Geneva, Switzerland. ...


However, since the particle momentum increases during acceleration, it is necessary to turn up the magnetic field B in proportion to maintain constant curvature of the orbit. In consequence synchrotrons cannot accelerate particles continuously, as cyclotrons can, but must operate cyclically, supplying particles in bunches, which are delivered to a target or an external beam in beam "spills" typically every few seconds. Note that since high energy synchrotrons do most of their work on particles that are already traveling at nearly the speed of light c, the time to complete one orbit of the ring is nearly constant, as is the frequency of the RF power needed to drive the acceleration.


Note also a further point about modern synchrotrons: because the beam aperture is small and the magnetic field does not cover the entire area of the particle orbit as it does for a cyclotron, several necessary functions can be separated. Instead of one huge magnet, one has a line of hundreds of bending magnets, enclosing (or enclosed by) vacuum connecting pipes. The focusing of the beam is handled independently by specialized quadrupole magnets, while the acceleration itself is accomplished in separate RF sections, rather similar to short linear accelerators. Also, there is no necessity that cyclic machines be circular, but rather the beam pipe may have straight sections between magnets where beams may collide. be cooled, etc. In particle accelerators, quadrupole magnets are used to focus beams of charged particles. ...

Aerial photo of the Tevatron at Fermilab. The main accelerator is the ring above; the one below (about one-third the diameter, despite appearances) is for preliminary acceleration, beam cooling and storage, etc.
Aerial photo of the Tevatron at Fermilab. The main accelerator is the ring above; the one below (about one-third the diameter, despite appearances) is for preliminary acceleration, beam cooling and storage, etc.

More complex modern synchrotrons such as the Tevatron, LEP, and LHC (still under construction) may deliver the particle bunches into storage rings of magnets with constant B, where they can continue to orbit for long periods for experimentation or further acceleration. The highest-energy machines such as the Tevatron and LHC are actually accelerator complexes, with a cascade of specialized elements in series, including linear accelerators for initial beam creation, one or more low energy synchrotrons to reach intermediate energy, storage rings where beams can be accumulated or "cooled" (reducing the magnet aperture required and permitting tighter focusing; see beam cooling), and a last large ring for final acceleration and experimentation. Fermi National Accelerator Laboratory File links The following pages link to this file: Fermilab Categories: United States government images ... Fermi National Accelerator Laboratory File links The following pages link to this file: Fermilab Categories: United States government images ... Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... Aerial view of the Fermilab site. ... Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... The Large Electron-Positron Collider (usually called LEP for short. ... , The Large Hadron Collider (LHC) is a particle accelerator and Hadron collider located at CERN, near Geneva, Switzerland. ... A small storage ring at SLAC. This particlular storage ring is one of the two small storage rings or circular cyclotron. ... In a storage ring the charged particles travel in bunches in potential hollows. ...


Electron synchrotrons

Segment of an electron synchrotron at DESY
Segment of an electron synchrotron at DESY

Circular electron accelerators fell somewhat out of favor for particle physics around the time that SLAC was constructed, because their synchrotron losses were considered economically prohibitive and because their beam intensity was lower than for the unpulsed linear machines. The Cornell Electron Synchrotron, built at low cost in the late 1960s, was the first in a series of high-energy circular electron accelerators built for fundamental particle physics, culminating in the LEP at CERN. Image File history File links Download high resolution version (984x670, 128 KB) de: Bildbeschreibung: Teilchenbeschleunigersegment bei DESY (Deutsches Elektronen-Synchrotron) in Hamburg, Deutschland Fotograf: Vincent Pál, Erlaubnis erteilt; Erlaubnis von DESY wird z. ... Image File history File links Download high resolution version (984x670, 128 KB) de: Bildbeschreibung: Teilchenbeschleunigersegment bei DESY (Deutsches Elektronen-Synchrotron) in Hamburg, Deutschland Fotograf: Vincent Pál, Erlaubnis erteilt; Erlaubnis von DESY wird z. ... The DESY (Deutsches Elektronen Synchrotron, German Electron Synchrotron) is the biggest German research center for particle physics, with sites in Hamburg and Zeuthen. ... The Stanford Linear Accelerator Center (SLAC) is a U.S. national laboratory operated by Stanford University for the U.S. Department of Energy. ... The Large Electron-Positron Collider (usually called LEP for short. ...


A large number of electron synchrotrons have been built in the past two decades, specialized to be synchrotron light sources, of ultraviolet light and X rays; see below.


Storage rings

Main article: Storage ring

For some applications, it is useful to store beams of high energy particles for some time (with modern high vacuum technology, up to many hours) without further acceleration. This is especially true for colliding beam accelerators, in which two beams moving in opposite directions are made to collide with each other, with a large gain in effective collision energy. Because relatively few collisions occur at each pass through the intersection point of the two beams, it is customary to first accelerate the beams to the desired energy, and then store them in storage rings, which are essentially synchrotron rings of magnets, with no significant RF power for acceleration. A small storage ring at SLAC. This particlular storage ring is one of the two small storage rings or circular cyclotron. ... Look up Vacuum in Wiktionary, the free dictionary. ... A collider is a type of a particle accelerator with two opposite beams of the particles. ...


Synchrotron radiation sources

Some circular accelerators have been built to deliberately generate radiation (called synchrotron light) as X-rays also called synchrotron radiation, for example the Diamond Light Source being built at the Rutherford Appleton Laboratory in England or the Advanced Photon Source at Argonne National Laboratory in Illinois, USA. High-energy X-rays are useful for X-ray spectroscopy of proteins or X-ray absorption fine structure (XAFS) for example. Synchrotron radiation emerging from a beam port. ... An X-ray picture (radiograph), taken by Wilhelm Röntgen in 1896, of his wife, Anna Bertha Ludwigs[1] hand X-rays (or Röntgen rays) are a form of electromagnetic radiation with a wavelength in the range of 10 to 0. ... Diamond Light Source is a synchrotron research facility located on the Rutherford Appleton Laboratory in Oxfordshire, England. ... Aerial view of Rutherford Appleton Lab. ... For other uses, see England (disambiguation). ... The Advanced Photon Source (APS) at Argonne National Laboratory is a national synchrotron_radiation light source research facility funded by the United States Department of Energy, Office of Science, Office of Basic Energy Sciences. ... Aerial photo of the Advanced Photon Source at Argonne National Laboratory. ... Official language(s) English[1] Capital Springfield Largest city Chicago Largest metro area Chicago Metropolitan Area Area  Ranked 25th  - Total 57,918 sq mi (140,998 km²)  - Width 210 miles (340 km)  - Length 390 miles (629 km)  - % water 4. ... X-ray spectroscopy is a gathering name for several spectroscopic techniques for determining the electronic structure of materials by using x-ray excitation. ... A representation of the 3D structure of myoglobin showing coloured alpha helices. ... X-ray absorption fine structure (XAFS) is a specific structure observed in X-ray absorption spectroscopy (XAS). ...


Synchrotron radiation is more powerfully emitted by lighter particles, so these accelerators are invariably electron accelerators. Synchrotron radiation allows for better imaging as researched and developed at SLAC's SPEAR. For other uses, see Electron (disambiguation). ... The Stanford Linear Accelerator Center (SLAC) is a United States Department of Energy National Laboratory operated by Stanford University under the programmatic direction of the U.S. Department of Energy Office of Science. ...


History

Lawrence's first cyclotron was a mere 4 inches (100 mm) in diameter. Later he built a machine with a 60 in dia pole face, and planned one with a 184-inch dia, which was, however, taken over for WWII-related work connected with uranium isotope separation; after the war it continued in service for research and medicine over many years. A list of particle accelerators used for particle physics experiments. ... A list of particle accelerators used for particle physics experiments. ... German soldiers at the Battle of Stalingrad World War II was the most extensive and costly armed conflict in the history of the world, involving the great majority of the worlds nations, being fought simultaneously in several major theatres, and costing tens of millions of lives. ... Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes, for example separating natural uranium into enriched uranium and depleted uranium. ...


The first large proton synchrotron was the Cosmotron at Brookhaven National Laboratory, which accelerated protons to about 3 GeV. The Bevatron at Berkeley, completed in 1954, was specifically designed to accelerate protons to sufficient energy to create anti-protons, and verify the particle-antiparticle symmetry of nature, then only strongly suspected. The AGS at Brookhaven was the first large synchrotron with alternating gradient, "strong focusing" magnets, which greatly reduced the required aperture of the beam, and correspondingly the size and cost of the bending magnets. The Proton Synchrotron, built at CERN, was the first major European particle accelerator and generally similar to the AGS. The Cosmotron was a particle accelerator, specifically a proton synchrotron, at Brookhaven National Laboratory. ... ≠ Aerial view of Brookhaven National Laboratory. ... Edwin McMillan and Edward Lofgren on the shielding of the Bevatron. ... For other senses of this term, see antimatter (disambiguation). ... AGS is a three-letter abbreviation with multiple meanings, as described below: // AngryStatic, a PC Support and Solutions Company Alpha Gamma Sigma, an honor society in California the American Gemological Society the American Geographical Society the American Gita Society the American Glovebox Society Automobiles Gonfaronnaises Sportives, a defunct Formula 1... The surface above the PS at CERN. With more than 45 years to be smoothed out and have buildings built around it, the ring-shaped hill containing the accelerator is not completely obvious--but it can be seen curving around on the left side of the image. ... CERN logo The European Organization for Nuclear Research (French: ), commonly known as CERN (see Naming), pronounced (or in French), is the worlds largest particle physics laboratory, situated just northwest of Geneva on the border between France and Switzerland. ...


The Fermilab Tevatron has a ring with a beam path of 4 miles (6 km). The largest circular accelerator ever built was the LEP synchrotron at CERN with a circumference 26.6 kilometers, which was an electron/positron collider. It has been dismantled and the underground tunnel is being reused for a proton/proton collider called the LHC, due to start operation in May 2008. The aborted Superconducting Supercollider (SSC) in Texas would have had a circumference of 87 km. Construction was started in 1991, but abandoned in 1993. Very large circular accelerators are invariably built in underground tunnels a few metres wide to minimize the disruption and cost of building such a structure on the surface, and to provide shielding against intense secondary radiations that may occur. These are extremely penetrating at high energies. Fermi National Accelerator Laboratory located in Batavia near Chicago, Illinois is a U.S. Department of Energy national laboratory specializing in high-energy particle physics, operated for the Department of Energy by the Universities Research Association (URA). ... Tevatron is a circular particle accelerator (or synchrotron) at the Fermi National Accelerator Laboratory in Batavia, Illinois. ... The Large Electron-Positron Collider (usually called LEP for short. ... Synchrotrons are now mostly used for producing monochromatic high intensity X-ray beams; here, the synchrotron is the circular track, off which the beamlines branch. ... The first detection of the positron in 1932 by Carl D. Anderson The positron is the antiparticle or the antimatter counterpart of the electron. ... , The Large Hadron Collider (LHC) is a particle accelerator and Hadron collider located at CERN, near Geneva, Switzerland. ... The Superconducting Super Collider (often abbreviated as SSC) was a ring particle accelerator which was planned to be built in the area around Waxahachie, Texas. ... For other uses, see Texas (disambiguation). ... Year 1991 (MCMXCI) was a common year starting on Tuesday (link will display the 1991 Gregorian calendar). ... Year 1993 (MCMXCIII) was a common year starting on Friday (link will display full 1993 Gregorian calendar). ...


Current accelerators such as the Spallation Neutron Source, incorporate superconducting cryomodules. The Relativistic Heavy Ion Collider, and upcoming Large Hadron Collider also make use of superconducting magnets and RF cavity resonators to accelerate particles. April 2005 aerial photo of the SNS site, Oak Ridge, Tennessee, USA. The Spallation Neutron Source (SNS) is an accelerator-based neutron source being built in Oak Ridge, Tennessee, USA, by the U.S. Department of Energy (DOE). ... A cryomodule is that section, or sections of a linear particle accelerator composed of superconducting niobium cavities used in a linear accelerator, or linac. ... The Relativistic Heavy Ion Collider at Brookhaven National Laboratory. ... , The Large Hadron Collider (LHC) is a particle accelerator and Hadron collider located at CERN, near Geneva, Switzerland. ... A magnet levitating above a high-temperature superconductor, cooled with liquid nitrogen. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


Targets and detectors

The output of a particle accelerator can generally be directed towards multiple lines of experiments, one at a given time, by means of a deviating electromagnet. This makes it possible to operate multiple experiments without needing to move things around or shutting down the entire accelerator beam. Except for synchrotron radiation sources, the purpose of an accelerator is to generate high-energy particles for interaction with matter. An electromagnet is a type of magnet in which the magnetic field is produced by the flow of an electric current. ...


This is usually a fixed target, such as the phosphor coating on the back of the screen in the case of a television tube; a piece of uranium in an accelerator designed as a neutron source; or a tungsten target for an X-ray generator. In a linac, the target is simply fitted to the end of the accelerator. The particle track in a cyclotron is a spiral outwards from the centre of the circular machine, so the accelerated particles emerge from a fixed point as for a linear accelerator. Green screen A phosphor is a substance that exhibits the phenomenon of phosphorescence (sustained glowing after exposure to light or energised particles such as electrons). ... This article is about the chemical element. ...


For synchrotrons, the situation is more complex. Particles are accelerated to the desired energy. Then, a fast acting dipole magnet is used to switch the particles out of the circular synchrotron tube and towards the target.


A variation commonly used for particle physics research is a collider, also called a storage ring collider. Two circular synchrotons are built in close proximity - usually on top of each other and using the same magnets (which are then of more complicated design to accommodate both beam tubes). Bunches of particles travel in opposite directions around the two accelerators and collide at intersections between them. This can increase the energy enormously; whereas in a fixed-target experiment the energy available to produce new particles is proportional to the square root of the beam energy, in a collider the available energy is linear. Thousands of particles explode from the collision point of two relativistic (100 GeV per nucleon) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... A collider is a type of a particle accelerator with two opposite beams of the particles. ...


Higher energies

At present the highest energy accelerators are all circular colliders, but it is likely that limits have been reached in respect of compensating for synchrotron radiation losses for electron accelerators, and the next generation will probably be linear accelerators 10 times the current length. An example of such a next generation electron accelerator is the 40 km long International Linear Collider, due to be constructed between 2015-2020. The International Linear Collider is a proposed linear particle accelerator. ...


As of 2005, it is believed that plasma wakefield acceleration in the form of electron-beam 'afterburners' and standalone laser pulsers will provide dramatic increases in efficiency within two to three decades. In plasma wakefield accelerators, the beam cavity is filled with a plasma (rather than vacuum). A short pulse of electrons or laser light either constitutes or immediately trails the particles that are being accelerated. The pulse disrupts the plasma, causing the charged particles in the plasma to integrate into and move toward the rear of the bunch of particles that are being accelerated. This process transfers energy to the particle bunch, accelerating it further, and continues as long as the pulse is coherent.[3] Plasma acceleration is a technique for accelerating charged particles, such as electrons, positrons and ions, using an electric field associated with an electron plasma wave. ...


Energy gradients as steep as 200 GeV/m have been achieved over millimeter-scale distances using laser pulsers[4] and gradients approaching 1 GeV/m are being produced on the multi-centimeter-scale with electron-beam systems, in contrast to a limit of about 0.1 GeV/m for radio-frequency acceleration alone. Existing electron accelerators such as SLAC could use electron-beam afterburners to greatly increase the energy of their particle beams, at the cost of beam intensity. Electron systems in general can provide tightly collimated, reliable beams; laser systems may offer more power and compactness. Thus, plasma wakefield accelerators could be used — if technical issues can be resolved — to both increase the maximum energy of the largest accelerators and to bring high energies into university laboratories and medical centres. The Stanford Linear Accelerator Center (SLAC) is a U.S. national laboratory operated by Stanford University for the U.S. Department of Energy. ...


Black hole production

In the next few decades, the possibility of black hole production at the highest energy accelerators may arise, if certain predictions of superstring theory are accurate.[5][6] If they are produced, it is thought that black holes would evaporate extremely quickly via Bekenstein-Hawking radiation. However, the existence of the Bekenstein-Hawking radiation is controversial.[7] It is also thought that an analogy between colliders and cosmic rays demonstrates collider safety. If colliders can produce black holes, cosmic rays (and particularly ultra-high-energy cosmic rays) should have been producing them for eons, and they have yet to harm us.[8] However, cosmic rays travel at relativistic speeds; it is thought that the micro black holes to be created by the LHC, for example, will move far slower than that, giving them time to interact with surrounding matter. For other uses, see Black hole (disambiguation). ... Superstring theory is an attempt to explain all of the particles and fundamental forces of nature in one theory by modeling them as vibrations of tiny supersymmetric strings. ... In physics, Hawking radiation (also known as Bekenstein-Hawking radiation) is a thermal radiation thought to be emitted by black holes due to quantum effects. ... Cosmic rays can loosely be defined as energetic particles originating outside of the Earth. ... Unsolved problems in physics: Why is it that some cosmic rays appear to possess energies that are theoretically too high? In high-energy physics, an ultra-high-energy cosmic ray (UHECR) is a cosmic ray (subatomic particle) which appears to have extreme kinetic energy, far beyond both its rest mass...


See also

Wikimedia Commons has media related to:
Particle accelerator

Image File history File links Commons-logo. ... Accelerator physics deals with the problems of building and operating particle accelerators. ... Anatoli Petrovich Bugorski (Russian: Анатолий Бугорский) (born 1942) is a Russian scientist who was involved in an accident with a particle accelerator in 1978. ... Spiral Galaxy ESO 269-57 Astrophysics is the branch of astronomy that deals with the physics of the universe, including the physical properties (luminosity, density, temperature, and chemical composition) of celestial objects such as stars, galaxies, and the interstellar medium, as well as their interactions. ... A beam dump is a device that absorbs a beam. ... In particle physics, a beamline is the line along which a beam of particles travels through, or when projected from, a particle accelerator. ... A betatron is a particle accelerator developed by Donald Kerst at the University of Illinois in 1940 to accelerate electrons. ... There are very few or no other articles that link to this one. ... A cryomodule is that section, or sections of a linear particle accelerator composed of superconducting niobium cavities used in a linear accelerator, or linac. ... A pair of Dee electrodes with loops of coolant pipes on their surface at the Lawrence Hall of Science. ... A dipole magnet, in particle accelerators, is a magnet constructed to create a homogeneous magnetic field over some distance. ... Electromagnetism is the physics of the electromagnetic field: a field which exerts a force on particles that possess the property of electric charge, and is in turn affected by the presence and motion of those particles. ... Ion implantation is a materials engineering process by which ions of a material can be implanted into another solid, thereby changing the physical properties of the solid. ... , The Large Hadron Collider (LHC) is a particle accelerator and Hadron collider located at CERN, near Geneva, Switzerland. ... Linear accelerator (LINAC) used for medical radiation therapy; example made by Siemens AG. A linear particle accelerator (also called a LINAC) is an electrical device for the acceleration of subatomic particles. ... This is a list of particles in particle physics, including currently known and hypothetical elementary particles, as well as the composite particles that can be built up from them. ... A particle beam is an accelerated stream of charged particles or atoms (often moving at very near the speed of light) which may be directed by magnets and focused by electrostatic lenses, although they may also be self-focusing (see Pinch). ... The Compact Muon Solenoid (CMS) is an example of a large particle detector. ... Thousands of particles explode from the collision point of two relativistic (100 GeV per nucleon) gold ions in the STAR detector of the Relativistic Heavy Ion Collider. ... Quadrapole magnets sometimes called correctors, are designed to create a magnetic field whose magnitude grows linearly with the radial distance from its longitudinal axis, which is usually centered on and parallel to the main motion of the charged particles. ... In a storage ring the charged particles travel in bunches in potential hollows. ... The Superconducting Super Collider (SSC) was a ring particle accelerator which was planned to be built in the area around Waxahachie, TX. It was planned to have a ring circumference of 87 km (54 miles) and an energy of 20 TeV per beam, potentially enough energy to create a Higgs... Synchrotrons are now mostly used for producing monochromatic high intensity X-ray beams; here, the synchrotron is the circular track, off which the beamlines branch. ...

External links

  • Hellborg, Ragnar, ed. Electrostatic Accelerators: Fundamentals and Applications [N.Y., N.Y.: Springer, 2005]. [1]

PDF is an abbreviation with several meanings: Portable Document Format Post-doctoral fellowship Probability density function There also is an electronic design automation company named PDF Solutions. ... CERN logo The European Organization for Nuclear Research (French: ), commonly known as CERN (see Naming), pronounced (or in French), is the worlds largest particle physics laboratory, situated just northwest of Geneva on the border between France and Switzerland. ... John L. Heilbron is an American historian of science and academia. ... University of California Press, also known as UC Press, is a publishing house associated with the University of California that engages in academic publishing. ...

Tandem accelerators

Amateur construction

References

  1. ^ how stuff works - atom smasher
  2. ^ http://news.bbc.co.uk/2/hi/science/nature/7324564.stm
  3. ^ Matthew Early Wright (April 2005). "Riding the Plasma Wave of the Future". Symmetry: Dimensions of Particle Physics (Fermilab/SLAC), p. 12.
  4. ^ Briezman, et al. "Self-Focused Particle Beam Drivers for Plasma Wakefield Accelerators." (PDF) Retrieved 13 May 2005.
  5. ^ An Interview with Dr. Steve Giddings http://www.esi-topics.com/blackholes/interviews/SteveGiddings.html
  6. ^ Phys. Rev. D 66, 091901 (2002) http://prola.aps.org/abstract/PRD/v66/i9/e091901
  7. ^ Adam D. Helfer (2003). ""Do black holes radiate?" Rept. Prog. Phys. 66: 943.
  8. ^ R. Jaffe et al., Rev. Mod. Phys. 72, 1125–1140 (2000).
is the 133rd day of the year (134th in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ...

  Results from FactBites:
 
Particle accelerator - Wikipedia, the free encyclopedia (2138 words)
In early particle accelerators a Cockcroft-Walton voltage multiplier was responsible for voltage multiplying.
DC accelerator types capable of accelerating particles to speeds sufficient to cause nuclear reactions are Cockcroft-Walton generators or voltage multipliers, which convert AC to high voltage DC, or Van de Graaff generators that use static electricity carried by belts.
A low-energy particle accelerator, an ion implanter is used in the manufacture of integrated circuits.
Particle accelerator - definition of Particle accelerator in Encyclopedia (1339 words)
In higher-energy accelerators, quadrupole magnets are used to focus the particles into a beam and prevent their mutual electrostatic repulsion from causing them to spread out.
As the particles approach the speed of light the switching rate of the electric fields becomes so high that they operate at microwave frequencies, and so microwave cavities are used in higher energy machines instead of simple plates.
Consequently particle physicists are increasingly using heavier particles such as protons in their accelerators to get to higher energies.
  More results at FactBites »

 
 

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