A cyclotron is a circular particle accelerator, a particular type of machine to electrically chargedAtomic particles (sub) (mainly. atomic nuclei) ions, giving a high speed. The accelerated particles can be used for irradiating a removable internal target (target) or are delivered in an external bundle for the run and possibly controlled observation ofcollision processes.
Speeding up is done by the charged particles (usually comes from an ion source) after injection into the center of a cylindrical vacuum box to submit to a combination of a vertically oriented magnetic field and a high frequency alternating electric field, which creates a horizontal gear. The magnetic field exerts a lorentz force on the particles, causing it to describe a horizontal circular orbit. As a result, groups together over and over again to the lasting particles electric field reverses direction, while that more exposed during the half turn-around time of a group of particles. With every pass is the electrical polarity so that acceleration occurs. The magnetic field is generated by a strong electromagnet with circular Poland. As the particles spiral they go out, get a greater speed while the period initially remains unchanged. Near the edge of the vacuum box landed, they have thus an energy many times larger than a single pass of the accelerating electric field. Because the versnellingspad is ' rolled up ', a cyclotron is much more compact than the rectilinear path in a Linear Accelerator, with benefits (and disadvantages) that this entails. With a beam extraction system can be placed outside the magnetic field and the particles in a opto-magnetic beam guidance system are transported to a place of destination.Schematic representation of the cyclotron according to Lawrence ' patent from 1934
The principle of the cyclotron was developed in 1929 by the American physicist Ernest Lawrence of the University of California at Berkeley. Along with Milton Stanley Livingston in 1931 he realized for the first time a working cyclotron with a magneetpool diameter of 4.5 inches (11.4 cm) and reached an energy for protons of 80 keV (similar to an accelerating field of 80,000 volts) at a really used field of 1800 volts. Six months later he reached with an 11 inch (27.8 cm) cyclotron 1 MeV. In 1939 under the direction of Lawrence was the 60-inch (152 cm) cyclotron with a 200-ton magnet and a bundle of 16 MeV deuterons operated. This led inter alia to the discovery of artificial transuranic elements neptunium and plutonium , such as.
As the energy was higher by cyclotrons reach, new phenomena could be discovered. In the pursuit of a higher energy particles it became necessary to take account of Albert Einsteins -effect (see theory of relativity): the more heavily at increasing speed and energy of the particles, causing the orbital period in a constant magnetic field during the acceleration increases. On the other hand would be met by varying the frequency of the alternating electric field (frequency modulation) over a period during which a ' burst ' particles from the Center to the outer course is accelerated. Thus was born in addition to the classic cyclotron and synchrotronthe synchrocyclotron . There will be a short-term deeltjesbursts delivered with relatively long intervals. On the other hand, the average gradient of the magnetic field to the outside so that the turn-around time increase remains constant (isochronous cyclotron). In this case, it creates a constant beam particles. Unless special precautions are taken, the bundle is still the ' accelerated ' subtree of groups together particles, in the form of sharp peaks with the period of high frequency electric field. About 1940 was started on the design of a synchrocyclotron in Berkeley with a diameter of 184 inches (467 cm) for acceleration energies above 100 MeV, which – delayed by the second World War (WW-II) – was completed in 1946 . In the research programme with this machine are plenty of important discoveries and breakthrough measurement data collected. This model is taken as a starting point for the design of numerous cyclotrons elsewhere.
To the beam intensity (number of accelerated particles per second) increase was in addition to improvements to the ion source and the vacuum, sometimes the acceleration process split in two. Two cyclotrons than ' in series '. The second cyclotron starts the gear in the final energy of the first. A special sector pattern in the strength of the magnetic field of this, makes this not only isochronous cyclotron, but at the same time that the number of accelerated particles group together as many may be larger (strong focusing). To minimize the size and operating costs is at the magnetic field generated by modern cyclotrons are increasingly using asuperconducting electromagnet.
Cyclotrons, which vary greatly in size dimension bundle, bundle to accelerate particles energy intensity and species were in the second half of the 20th century in many countries into use, mainly for research innuclear physics and particle physics and its applications. In 2009 are the most powerful cyclotrons in the research institutes TRIUMF in Vancouver, Canada, and the Paul Scherrer Institute (PSI) in Zurich,Switzerland. From the 1950s are also built for various small cyclotrons in nuclear applications ' tabletop', initially with beam energies of about 10 MeV. Today, worked on so small, cheap and efficient devices of high intensity with energies of tens of MeV, especially for the benefit of the synthesis of radio isotopes, of radiotherapy and material analysis.
In Netherlands was already for WW-II by the N.V. Philips gloeilampenfabrieken on the basis of the results in Berkeley started the development of a cyclotron. This allowed in Netherlands shortly after the war under the leadership of F.A. Heyn (Delft) and C.J. Bakker (later first Director of CERN) are started the construction of a cyclotron in a former gasworks in Amsterdam. In 1949, this first European cyclotron at the IKO in Amsterdam operated. In the meantime, the design was changed to a synchrocyclotron, so that the bundle could be reached higher energy and intensity than originally expected. This cyclotron produced until in the 1970s bundles of a.o. 26 MeV deuterons and 50 MeV protons, that were used for a research programme in Atomic nuclearspectroscopy, radiochemistry and nuclear reactions. A striking technical development at the cyclotron from 1964 is a spherical detector Setup at the time, groundbreaking for the GLOBE, simultaneously and comprehensively (in coincidence), measuring multiple nuclear particles emitted at nuclear collisions.Also in Netherlands were cyclotrons placed at universities and research institutes in Eindhoven (TUE), Amsterdam (VU), caps (NRG) and Groningen (KVI). The latter, now most modern cyclotron in Netherlands, called AGOR (Accélérateur Groningen-ORsay), was designed and built in collaboration between KVI and the Institut de Physique Nucléaire (IPN), where the construction was taking place in France. After testing the accelerator was disassembled and moved to Groningen. Since the beginning of 1996, AGOR particles bundles produced by both light and heavy ions for the purpose of scientific research. The cyclotron is equipped with external ion sources. There are several large experimental detection systems for nuclear physics research on KVI, which can be used in conjunction with supporting equipment. The largest facility is triµp, intended for the ' capture ' of radioactive ions produced with AGOR.