Cyclotrons: A survey
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clotrons: A Survey L. M. Onishchenko Joint Institute for Nuclear Research, Dubna, Russia Abstract—A survey is presented on the development and current status of cyclotrons used for proton and ion acceleration. Basic fields of application of cyclotrons are nuclear physics research, production and study of radioactive ions, and applied use, mainly in medicine. PACS numbers: 29.20.dg DOI: 10.1134/S106377960806004X
INTRODUCTION A cyclotron is the resonance accelerator of heavy charged particles (protons, ions) in which the frequency of the accelerating voltage and the leading magnetic field are constant in time. Particles in the cyclotron move along a spiral path outwards from the center. The maximum energy of protons accelerated in the (classical) cyclotron is about 20 MeV, and in a special (isochronous) cyclotron, up to 1 GeV (see Great Soviet Encyclopedia 28, 562 (1978)). More than 75 years passed since the cyclotron’s invention. Several hundreds of cyclotrons have been built during this period. Since 1959, the cyclotron community has been holding regular international conferences and publishing proceedings of these conferences, “International Conference on Cyclotrons and Their Applications.” Of course, during the first years of the existence of cyclotrons, before the cyclotron conferences began to be held, works devoted to cyclotrons were published in scientific periodicals, such as Science, Physics Review, Nuclear Instruments and Methods, Particle Accelerators, and reported at other conferences. Conferences are held once every three years in America, Europe, and Asia in turn. One of the conferences (in 1995) was held in Africa. The list of all conferences is given in the Appendix. The proceedings of the conferences, mainly, of the last two—Cyclotrons 2004, held in Tokyo, and Cyclotrons 2007, held in Sicily—were used in writing this survey. We have established the goal of describing the history of the creation and development of cyclotrons, the process of particle acceleration in cyclotrons, and their various applications. The survey includes three sections and two appendices. 1. THE CREATION AND DEVELOPMENT OF CYCLOTRONS In the preface to the book by Nahmias The Cyclotron, Frederick Joliot-Curie wrote that in 1919 Rutherford managed to transform nitrogen into oxygen and
thus perform the first transformation of matter by bombarding nitrogen atoms with α particles emitted by a natural radioactive element. Before 1932, α particles (from radioactive sources) were a unique source of charged particles, with an energy of 1–2 MeV, which could be used in nuclear physics. The first artificial source was the accelerator of Cockroft and Walton (direct acting accelerator), which accelerated hydrogen ions in a strong electric (electrostatic) field. They managed to obtain very-high-intensity beams of protons, deuterons, and helium nuclei with energies of up to 1 MeV; due to this, multiple nuclear reactions were discovered. The employed beams had an intensity on the order of 1015 s–1, which was one million times higher than that
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