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72-504: The Positron–Electron Tandem Ring Accelerator ( PETRA ) is one of the particle accelerators at the German national laboratory DESY in Hamburg , Germany . At the time of its construction, it was the biggest storage ring of its kind and still is DESY's second largest synchrotron after HERA . PETRA's original purpose was research in elementary particle physics . From 1978 to 1986, it

144-491: 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. There are more than 30,000 accelerators in operation around the world. There are two basic classes of accelerators: electrostatic and electrodynamic (or electromagnetic) accelerators. Electrostatic particle accelerators use static electric fields to accelerate particles. The most common types are

216-411: A klystron and a complex bending magnet arrangement which produces a beam of energy 6–30  MeV . 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. In the circular accelerator, particles move in

288-475: A storage ring device. Several sources claims that his Norwegian citizenship was ultimately revoked for working with the Nazi government, but this is not correct. His Norwegian passport was confiscated for some time and he accepted a penalty notice of NOK 5000, loss of civil liberties and to forfeit NOK 120000 of the amount he was paid in licence fees for use of his patent rights during the betatron development. In

360-430: A 3 km long waveguide, buried in a tunnel and powered by hundreds of large klystrons . It is still the largest linear accelerator in existence, and has been upgraded with the addition of storage rings and an electron-positron collider facility. It is also an X-ray and UV synchrotron photon source. Rolf Wider%C3%B8e Rolf Widerøe (11 July 1902 – 11 October 1996) was a Norwegian accelerator physicist who

432-402: A circle until they reach enough 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 smaller than a linear accelerator of comparable power (i.e.

504-553: A constant frequency by a RF accelerating power source, as the beam spirals outwards continuously. The particles are injected in the center of the magnet and are extracted at the outer edge at their maximum energy. Cyclotrons reach an energy limit because of relativistic effects whereby the particles effectively become more massive, so that their cyclotron frequency drops out of sync with the accelerating RF. Therefore, simple cyclotrons can accelerate protons only to an energy of around 15 million electron volts (15 MeV, corresponding to

576-696: 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. As the particles approach the speed of light the switching rate of the electric fields becomes so high that they operate at radio frequencies , and so microwave cavities are used in higher energy machines instead of simple plates. Linear accelerators are also widely used in medicine , for radiotherapy and radiosurgery . Medical grade linacs accelerate electrons using

648-427: A linac would have to be extremely long to have the equivalent power of a circular accelerator). 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

720-457: A linear accelerator prototype based on Isings proposal and made this the topic of his dissertation under Walter Rogowski . In 1928, he relocated to Berlin and started building protective relays during his work at AEG . In 1933 Hitler came to power in Germany and Widerøe decided to return to Norway. From his betatron experiment, he developed further ideas of particle acceleration without

792-514: A magnetic field which is fixed in time, but with a radial variation to achieve strong focusing , allows the beam to be accelerated with a high repetition rate but in a much smaller radial spread than in the cyclotron case. Isochronous FFAs, like isochronous cyclotrons, achieve continuous beam operation, but without the need for a huge dipole bending magnet covering the entire radius of the orbits. Some new developments in FFAs are covered in. A Rhodotron

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864-432: A reactor to produce tritium . An example of this type of machine is LANSCE at Los Alamos National Laboratory . Electrons propagating through a magnetic field emit very bright and coherent photon beams via synchrotron radiation . It has numerous uses in the study of atomic structure, chemistry, condensed matter physics, biology, and technology. A large number of synchrotron light sources exist worldwide. Examples in

936-589: A short time period, working in a locomotive facility of the Norwegian State Railways , where he fulfilled his 72-day military service. He went back to Germany in 1925. There he studied at the Technical University at Aachen , where he proposed a thesis in 1927 for an experimental betatron accelerator, incorporating the work of Swedish scientist Gustav Ising of 1924, which was not successful at first. Thus, Widerøe instead built

1008-426: A shorter distance in each orbit than they would in a classical cyclotron, thus remaining in phase with the accelerating field. The advantage of the isochronous cyclotron is that it 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 high magnetic field values required at

1080-614: A single piece in order to limit vibrations. PETRA III delivers hard X-ray beams of very high brilliance to over 40 experimental stations. Particle accelerator Large accelerators include the Relativistic Heavy Ion Collider at Brookhaven National Laboratory in New York and the largest accelerator, the Large Hadron Collider near Geneva, Switzerland, operated by CERN . It is

1152-849: A special class of light sources based on synchrotron radiation that provides shorter pulses with higher temporal coherence . A specially designed FEL is the most brilliant source of x-rays in the observable universe. The most prominent examples are the LCLS in the U.S. and European XFEL in Germany. More attention is being drawn towards soft x-ray lasers, which together with pulse shortening opens up new methods for attosecond science . Apart from x-rays, FELs are used to emit terahertz light , e.g. FELIX in Nijmegen, Netherlands, TELBE in Dresden, Germany and NovoFEL in Novosibirsk, Russia. Thus there

1224-474: 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. To accommodate relativistic effects the magnetic field needs to be increased to higher radii as is done in isochronous cyclotrons . An example of an isochronous cyclotron

1296-649: A straight line, or circular , using magnetic fields to bend particles in a roughly circular orbit. Magnetic induction accelerators accelerate particles by induction from an increasing magnetic field, as if the particles were the secondary winding in a transformer. The increasing magnetic field creates a circulating electric field which can be configured to accelerate the particles. Induction accelerators can be either linear or circular. Linear induction accelerators utilize ferrite-loaded, non-resonant induction cavities. Each cavity can be thought of as two large washer-shaped disks connected by an outer cylindrical tube. Between

1368-452: A target or an external beam in beam "spills" typically every few seconds. 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 cavity resonators used to drive the acceleration. In modern synchrotrons, the beam aperture is small and

1440-402: Is 3 km (1.9 mi) long. SLAC was originally an electron – positron collider but is now a X-ray Free-electron laser . 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

1512-405: Is a circular magnetic induction accelerator, invented by Donald Kerst in 1940 for accelerating electrons . The concept originates ultimately from Norwegian-German scientist Rolf Widerøe . 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

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1584-413: Is a great demand for electron accelerators of moderate ( GeV ) energy, high intensity and high beam quality to drive light sources. Everyday examples of particle accelerators are cathode ray tubes found in television sets and X-ray generators. These low-energy accelerators 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

1656-509: Is an industrial electron accelerator first proposed in 1987 by J. Pottier of the French Atomic Energy Agency (CEA) , manufactured by Belgian company Ion Beam Applications . It accelerates electrons by recirculating them across the diameter of a cylinder-shaped radiofrequency cavity. A Rhodotron has an electron gun, which emits an electron beam that is attracted to a pillar in the center of the cavity. The pillar has holes

1728-422: Is commonly used for sterilization. Electron beams are an on-off technology that provide a much higher dose rate than gamma or X-rays emitted by radioisotopes like cobalt-60 ( Co) or caesium-137 ( Cs). Due to the higher dose rate, less exposure time is required and polymer degradation is reduced. Because electrons carry a charge, electron beams are less penetrating than both gamma and X-rays. Historically,

1800-560: Is more often used for accelerators that employ oscillating rather than static electric fields. Due to the high voltage ceiling imposed by electrical discharge, in order to accelerate particles to higher energies, techniques involving dynamic fields rather than static fields are used. Electrodynamic acceleration can arise from either of two mechanisms: non-resonant magnetic induction , or resonant circuits or cavities excited by oscillating radio frequency (RF) fields. Electrodynamic accelerators can be linear , with particles accelerating in

1872-571: Is one of the electrodes. A low-energy particle accelerator called an ion implanter is used in the manufacture of integrated circuits . At lower energies, beams of accelerated nuclei are also used in medicine as particle therapy , for the treatment of cancer. 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. Electron beam processing

1944-402: Is still extremely popular today, with the electrostatic accelerators greatly out-numbering any other type, they are more suited to lower energy studies owing to the practical voltage limit of about 1 MV for air insulated machines, or 30 MV when the accelerator is operated in a tank of pressurized gas with high dielectric strength , such as sulfur hexafluoride . In a tandem accelerator

2016-468: 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 . The earliest operational circular accelerators were cyclotrons , invented in 1929 by Ernest Lawrence at the University of California, Berkeley . Cyclotrons have a single pair of hollow D-shaped plates to accelerate

2088-682: Is that the magnetic field need only be present over the actual region of the particle orbits, which is much narrower than that of the ring. (The largest cyclotron built in the US had a 184-inch-diameter (4.7 m) magnet pole, whereas the diameter of synchrotrons such as the LEP and LHC is nearly 10 km. The aperture of the two beams of the LHC is of the order of a centimeter.) The LHC contains 16 RF cavities, 1232 superconducting dipole magnets for beam steering, and 24 quadrupoles for beam focusing. Even at this size,

2160-604: Is the PSI Ring cyclotron in Switzerland, which provides protons at the energy of 590 MeV which corresponds to roughly 80% of the speed of light. The advantage of such a cyclotron is the maximum achievable extracted proton current which is currently 2.2 mA. The energy and current correspond to 1.3 MW beam power which is the highest of any accelerator currently existing. A classic cyclotron can be modified to increase its energy limit. The historically first approach

2232-415: Is the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory . Particle accelerators can also produce proton beams, which can produce proton-rich medical or research isotopes as opposed to the neutron-rich ones made in fission reactors ; however, recent work has shown how to make Mo , usually made in reactors, by accelerating isotopes of hydrogen, although this method still requires

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2304-645: 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

2376-946: The Diamond Light Source which has been 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 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 . Fixed-Field Alternating Gradient accelerators (FFA)s , in which

2448-484: The LHC is limited by its ability to steer the particles without them going adrift. This limit is theorized to occur at 14 TeV. 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

2520-609: The Tevatron, LEP , and LHC may deliver the particle bunches into storage rings of magnets with a constant magnetic field, 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

2592-687: The U.S. are SSRL at SLAC National Accelerator Laboratory , APS at Argonne National Laboratory, ALS at Lawrence Berkeley National Laboratory , and NSLS-II at Brookhaven National Laboratory . In Europe, there are MAX IV in Lund, Sweden, BESSY in Berlin, Germany, Diamond in Oxfordshire, UK, ESRF in Grenoble , France, the latter has been used to extract detailed 3-dimensional images of insects trapped in amber. Free-electron lasers (FELs) are

2664-494: 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. This has developed into an entire separate subject, called "beam physics" or "beam optics". More complex modern synchrotrons such as

2736-460: 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 synchrotron light ( X-rays ). Since the special theory of relativity requires that matter always travels slower than

2808-613: The disks is a ferrite toroid. A voltage pulse applied between the two disks causes an increasing magnetic field which inductively couples power into the charged particle beam. The linear induction accelerator was invented by Christofilos in the 1960s. Linear induction accelerators are capable of accelerating very high beam currents (>1000 A) in a single short pulse. They have been used to generate X-rays for flash radiography (e.g. DARHT at LANL ), and have been considered as particle injectors for magnetic confinement fusion and as drivers for free electron lasers . The Betatron

2880-435: The electrons can pass through. The electron beam passes through the pillar via one of these holes and then travels through a hole in the wall of the cavity, and meets a bending magnet, the beam is then bent and sent back into the cavity, to another hole in the pillar, the electrons then again go across the pillar and pass though another part of the wall of the cavity and into another bending magnet, and so on, gradually increasing

2952-499: The electrons moving at nearly the speed of light in a relatively small radius orbit. In a linear particle accelerator (linac), particles are accelerated in a straight line with a target of interest at one end. They are often 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

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3024-595: The end, early in 1946, he received an intermediate passport and emigrated to Switzerland. In 1946 he filed a patent in Norway for an accelerator based on synchronous acceleration. He would go on to publish over 180 papers in scientific and engineering journals, and filed over 200 patent applications over his lifetime. In his later life he devoted much time to medicinal technology, focusing on cancer treatment , including developing megavolt radiation therapy technologies. He would collaborate with CERN beginning in 1952 doing

3096-461: The energy of the beam until it is allowed to exit the cavity for use. The cylinder and pillar may be lined with copper on the inside. Ernest Lawrence's first cyclotron was a mere 4 inches (100 mm) in diameter. Later, in 1939, he built a machine with a 60-inch diameter pole face, and planned one with a 184-inch diameter in 1942, which was, however, taken over for World War II -related work connected with uranium isotope separation ; after

3168-583: The facilities at DESY. Scientists from China, France, Israel, the Netherlands, Norway, the United Kingdom and the USA participated in the first experiments at PETRA alongside many German colleagues. In 1990, the facility was taken into operation again under the name PETRA II as a pre-accelerator for protons and electrons/positrons for the new particle accelerator HERA . In March 1995, PETRA II

3240-623: The fact that many modern accelerators create collisions between two subatomic particles , rather than a particle and an atomic nucleus. Beams of high-energy particles are useful for fundamental and applied research in the sciences and also in many technical and industrial fields unrelated to fundamental research. There are approximately 30,000 accelerators worldwide; of these, only about 1% are research machines with energies above 1 GeV , while about 44% are for radiotherapy , 41% for ion implantation , 9% for industrial processing and research, and 4% for biomedical and other low-energy research. For

3312-409: The first accelerators used simple technology of a single static high voltage to accelerate charged particles. The charged particle was accelerated through an evacuated tube with an electrode at either end, with the static potential across it. Since the particle passed only once through the potential difference, the output energy was limited to the accelerating voltage of the machine. While this method

3384-412: The first operational linear particle accelerator , the betatron , as well as 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

3456-411: The magnet aperture required and permitting tighter focusing; see beam cooling ), and a last large ring for final acceleration and experimentation. Circular electron accelerators fell somewhat out of favor for particle physics around the time that SLAC 's linear particle accelerator was constructed, because their synchrotron losses were considered economically prohibitive and because their beam intensity

3528-412: The magnetic field does not cover the entire area of the particle orbit as it does for a cyclotron, so 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 design of synchrotrons was revolutionized in the early 1950s with the discovery of the strong focusing concept. The focusing of

3600-481: 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 , and 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 ,

3672-528: The necessity of high voltage. The method was resonating particles with a radio frequency electric field to add energy to each traversal of the field. This experiment was successful and published in 1928, and became the progenitor of all high-energy particle accelerators. Widerøe's article was studied by Ernest Lawrence in the United States, and used as the basis for his creation of the cyclotron in 1929. In 1941 his younger brother Viggo Widerøe

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3744-517: The need for a huge magnet of large radius and constant field over the larger orbit demanded by high energy. The second approach to the problem of accelerating relativistic particles is the isochronous cyclotron . In such a structure, the accelerating field's frequency (and the cyclotron resonance frequency) is kept constant for all energies by shaping the magnet poles so to increase magnetic field with radius. Thus, all particles get accelerated in isochronous time intervals. Higher energy particles travel

3816-455: The outer edge of the structure. Synchrocyclotrons have not been built since the isochronous cyclotron was developed. To reach still higher energies, with relativistic mass approaching or exceeding the rest mass of the particles (for protons, billions of electron volts or 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

3888-412: 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

3960-411: 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, having conceived and built

4032-449: The potential is used twice to accelerate the particles, by reversing the charge of the particles while they are inside the terminal. This is possible with the acceleration of atomic nuclei by using anions (negatively charged ions ), and then passing the beam through a thin foil to strip electrons off the anions inside the high voltage terminal, converting them to cations (positively charged ions), which are accelerated again as they leave

4104-434: 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

4176-571: 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, scientists 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. This elementary particle physicists tend to use machines creating beams of electrons, positrons, protons, and antiprotons , interacting with each other or with

4248-405: The simplest nuclei (e.g., hydrogen or deuterium ) at the highest possible energies, generally hundreds of GeV or more. The largest and highest-energy particle accelerator used for elementary particle physics is the Large Hadron Collider (LHC) at CERN , operating since 2009. Nuclear physicists and cosmologists may use beams of bare atomic nuclei , stripped of electrons, to investigate

4320-426: The speed of light in vacuum , in high-energy accelerators, as the energy increases the particle speed approaches the speed of light as a limit, but never attains it. 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,

4392-471: 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 . The largest such particle accelerator

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4464-552: The summer of 1920 at the Halling School in Oslo , Widerøe left for the university of Karlsruhe , Germany , to study electrical engineering . There he conceived the concept of electromagnetic induction to accelerate electrons, which became the basis of what would be known as betatron . This idea was to use a vortex field surrounding a magnetic field to accelerate electrons in a tube. In 1924, he returned to Norway for

4536-401: The terminal. The two main types of electrostatic accelerator are the Cockcroft–Walton accelerator , which uses a diode-capacitor voltage multiplier to produce high voltage, and the Van de Graaff accelerator , which uses a moving fabric belt to carry charge to the high voltage electrode. Although electrostatic accelerators accelerate particles along a straight line, the term linear accelerator

4608-463: The third incarnation for the PETRA storage ring, serving a regular user programme as one of the most brilliant storage-ring-based X-ray sources worldwide since 2009. The accelerator produces a particle energy of 6 GeV. There are currently three experimental halls (named after various famous scientists). The largest, named Max von Laue Hall , has a concrete floor over 300 m long that was poured as

4680-573: The war it continued in service for research and medicine over many years. The first large proton synchrotron was the Cosmotron at Brookhaven National Laboratory , which accelerated protons to about 3  GeV (1953–1968). The Bevatron at Berkeley, completed in 1954, was specifically designed to accelerate protons to enough energy to create antiprotons , and verify the particle–antiparticle symmetry of nature, then only theorized. The Alternating Gradient Synchrotron (AGS) at Brookhaven (1960–)

4752-578: Was arrested for resistance work. In 1943 the Germans "invited" Rolf Widerøe to Germany to continue to work on the Betatron . Inspired by the opportunity to continue his research and promises that his brother would have a better situation in his imprisonment, he agreed to go to Hamburg and start building a German Betatron. During this period, already in 1943, he introduced the theoretical concept of colliding particles head-on to increase interaction energy and

4824-551: Was equipped with undulators to create greater amounts of synchrotron radiation with higher energies, especially in the X-ray part of the spectrum. PETRA II served the Hamburg Synchrotron Radiation Laboratory (HASYLAB) at DESY as a source of high-energy synchrotron radiation in three test experimental areas. In PETRA II, positrons were accelerated to up to 12 GeV. PETRA III is

4896-648: Was lower than for the unpulsed linear machines. The Cornell Electron Synchrotron , built at low cost in the late 1970s, was the first in a series of high-energy circular electron accelerators built for fundamental particle physics, the last being LEP , built at CERN, which was used from 1989 until 2000. A large number of electron synchrotrons have been built in the past two decades, as part of synchrotron light sources that emit ultraviolet light and X rays; see below. Some circular accelerators have been built to deliberately generate radiation (called synchrotron light ) as X-rays also called synchrotron radiation, for example

4968-414: Was the synchrocyclotron , which accelerates the particles in bunches. It uses a constant magnetic field B {\displaystyle B} , but reduces the accelerating field's frequency so as to keep the particles in step as they spiral outward, matching their mass-dependent cyclotron resonance frequency. This approach suffers from low average beam intensity due to the bunching, and again from

5040-502: 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 (1959–), was the first major European particle accelerator and generally similar to the AGS. The Stanford Linear Accelerator , SLAC, became operational in 1966, accelerating electrons to 30 GeV in

5112-570: Was the originator of many particle acceleration concepts, including the resonance accelerator and the betatron accelerator. Widerøe was born in Kristiania (now Oslo) in 1902 as a son of the mercantile agent Theodor Widerøe (1868–1947) and Carla Johanne Launer (1875–1971). He was a brother of the aviator and entrepreneur Viggo Widerøe who became the founder of the Norwegian airline Widerøe . After his A-level exams ( Examen artium ) in

5184-459: Was used to study electron – positron collisions with the four experiments JADE , MARK-J , PLUTO and TASSO . The discovery of the gluon , the carrier particle of the strong nuclear force, by the TASSO collaboration in 1979 is counted as one of the biggest successes. PETRA was able to accelerate electrons and positrons to 19 GeV. Research at PETRA led to an intensified international use of

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