Editing Cyclotron (section)

=== Origins ===
A key limitation of the earliest charged particle accelerators was that increasing the particle energy required extending the length of the acceleration path, which was only feasible and practical up to a certain point. In 1927, while a student at Kiel, German physicist [[Max Steenbeck]] was the first to formulate the concept of the cyclotron, but he was discouraged from pursuing the idea further.<ref>[http://ark.cdlib.org/ark:/13030/ft5s200764/ Lawrence and His Laboratory] - ''II — A Million Volts or Bust'' 81–82 in Heilbron, J. L., and Robert W. Seidel ''Lawrence and His Laboratory: A History of the Lawrence Berkeley Laboratory', Volume I.'' (Berkeley:  University of California Press, 2000)</ref> In late 1928 and early 1929, Hungarian physicist [[Leo Szilárd]] filed patent applications in Germany for the [[linear accelerator]], cyclotron, and [[betatron]].<ref name="Dannen-20012">{{cite journal |last1=Dannen |first1=Gene |date=March 2001 |title=Szilard's Inventions Patently Halted |url=https://physicstoday.scitation.org/doi/10.1063/1.1366083?journalCode=pto&ver=pdfcov |journal=Physics Today |volume=54 |issue=3 |pages=102–104 |bibcode=2001PhT....54c.102D |doi=10.1063/1.1366083 |access-date=31 January 2022}}</ref> In these applications, Szilárd became the first person to discuss the resonance condition for a circular accelerating apparatus. However, neither Steenbeck's ideas nor Szilard's patent applications were ever published and therefore did not contribute to the development of the cyclotron.<ref>{{cite journal |last1=Telegdi |first1=Valentine L. |date=October 2000 |title=Szilard as Inventor: Accelerators and More |journal=Physics Today |volume=53 |issue=10 |pages=25–28 |bibcode=2000PhT....53j..25T |doi=10.1063/1.1325189 |access-date=|doi-access=free}}</ref> 

Several months later, in the early summer of 1929, Ernest Lawrence independently conceived the cyclotron concept after reading a paper by [[Rolf Widerøe]] describing a drift tube accelerator.<ref>{{cite journal |last=Widerøe |first=R. |year=1928 |title=Ueber Ein Neues Prinzip Zur Herstellung Hoher Spannungen |journal=[[Archiv für Elektronik und Übertragungstechnik]] |language=de |volume=21 |issue=4 |pages=387–406 |doi=10.1007/BF01656341 |s2cid=109942448}}</ref><ref>{{cite web |date=8 December 2008 |title=Breaking Through: A Century of Physics at Berkeley 1886–1968 2. The Cyclotron. |url=http://bancroft.berkeley.edu/Exhibits/physics/bigscience02.html |url-status=dead |archive-url=https://web.archive.org/web/20120527183442/http://bancroft.berkeley.edu/Exhibits/physics/bigscience02.html |archive-date=2012-05-27 |publisher=[[Bancroft Library]], [[UC Berkeley]]}}</ref><ref>{{cite conference |last1=Livingston |first1=M. Stanley |date=19–22 August 1975 |title=The History of the Cyclotron |url=https://accelconf.web.cern.ch/c75/papers/j-01.pdf |location=Zurich, Switzerland |pages=635–638 |book-title=Proceedings of the 7th International Conference on Cyclotrons and their Applications}}</ref> He published a paper in ''[[Science (journal)|Science]]'' in 1930 (the first published description of the cyclotron concept), after a student of his built a crude model in April of that year.<ref>{{cite journal |author1=E. O. Lawrence |author2=N. E. Edlefsen |year=1930 |title=On the Production of High Speed Protons |journal=Science |volume=72 |issue=1867 |pages=376–377 |doi=10.1126/science.72.1867.372 |pmid=17808988 |s2cid=56202243}}</ref> He patented the device in 1932.<ref name="Lawrence2">{{cite journal |last1=Lawrence |first1=Earnest O. |last2=Livingston |first2=M. Stanley |date=April 1, 1932 |title=The Production of High Speed Light Ions Without the Use of High Voltages |journal=Physical Review |publisher=American Physical Society |volume=40 |issue=1 |pages=19–35 |bibcode=1932PhRv...40...19L |doi=10.1103/PhysRev.40.19 |doi-access=free}}</ref><ref name="Physics2">{{cite book |last1=Alonso |first1=M. |url=https://archive.org/details/physics00alon |title=Physics |last2=Finn |first2=E. |publisher=[[Addison Wesley]] |year=1992 |isbn=978-0-201-56518-8 |url-access=registration}}</ref>

To construct the first such device, Lawrence used large electromagnets recycled from obsolete [[Arc converter|arc converters]] provided by the [[Federal Telegraph Company]].<ref>{{cite journal |last=Mann |first=F. J. |date=December 1946 |title=Federal Telephone and Radio Corporation, A Historical Review: 1909–1946 |journal=Electrical Communication |volume=23 |issue=4 |pages=397–398}}</ref> He was assisted by a graduate student, [[M. Stanley Livingston]]. Their first working cyclotron became operational on January 2, 1931.  This machine had a diameter of {{convert|4.5|in|cm}}, and accelerated protons to an energy up to 80&nbsp;[[Electronvolt|keV]].<ref name="aipexhibit2">{{cite web |title=The First Cyclotrons |url=https://history.aip.org/exhibits/lawrence/first.htm |access-date=7 June 2022 |publisher=[[American Institute of Physics]]}}</ref><ref name="c609">{{cite web |title=The Centennial of The University of California, 1868-1968 |url=https://oac.cdlib.org/view?docId=hb4v19n9zb;NAAN=13030&doc.view=frames&chunk.id=div00569&toc.depth=1&toc.id=div00015&brand=calisphere |access-date=2024-12-26 |website=Online Archive of California}}</ref>

At the Radiation Laboratory on the campus of the [[University of California, Berkeley]] (now the [[Lawrence Berkeley National Laboratory]]), Lawrence and his collaborators went on to construct a series of cyclotrons which were the most powerful accelerators in the world at the time; a {{convert|27|in|cm|0|abbr=on}} 4.8&nbsp;MeV machine (1932), a {{convert|37|in|cm|0|abbr=on}} 8&nbsp;MeV machine (1937), and a {{convert|60|in|cm|0|abbr=on}} 16&nbsp;MeV machine (1939). Lawrence received the 1939 [[Nobel Prize in Physics]] for the invention and development of the cyclotron and for results obtained with it.<ref>{{cite web |title=The Nobel Prize in Physics 1939 |url=http://nobelprize.org/nobel_prizes/physics/laureates/1939/index.html |url-status=live |archive-url=https://web.archive.org/web/20081024052532/http://nobelprize.org/nobel_prizes/physics/laureates/1939/index.html |archive-date=24 October 2008 |access-date=9 October 2008 |publisher=Nobel Foundation}}</ref>

The first European cyclotron was constructed in 1934 in the [[Soviet Union]] by Mikhail Alekseevich Eremeev, at the [[Leningrad Physico-Technical Institute]]. It was a small design based a prototype by Lawrence, with a 28 cm diameter capable of achieving 530 keV proton energies. Research quickly refocused around the construction of a larger MeV-level cyclotron, in the physics department of the [[V.G. Khlopin Radium Institute]] in Leningrad, headed by {{Interlanguage link multi|Vitaly Khlopin|ru|Хлопин, Виталий Григорьевич|preserve=1}}. This instrument was first proposed in 1932 by [[George Gamow]] and {{Interlanguage link multi|Lev Mysovskii|ru|Мысовский, Лев Владимирович|preserve=1}} and was installed and became operative in March 1937 at 100 cm (39 in) diameter and 3.2 MeV proton energies.<ref>{{cite journal |last=Emelyanov |first=V. S. |year=1971 |title=Nuclear Energy in the Soviet Union |url=https://books.google.com/books?id=jQsAAAAAMBAJ&pg=PA38 |journal=[[Bulletin of the Atomic Scientists]] |volume=27 |issue=9 |pages=39 |bibcode=1971BuAtS..27i..38E |doi=10.1080/00963402.1971.11455411 |quote=State Institute of Radium, founded in 1922, now known as V. G. Khlopin Radium Institute|url-access=subscription }}</ref><ref name="h373">{{cite web |title=Радиевый институт. Хроника событий. История коллекций. |url=https://elib.biblioatom.ru/text/radievyy-institut_2023/p155/?hl=%D0%BC%D0%B0%D1%80%D1%82%201937 |access-date=2024-12-27 |website=Электронная библиотека /// История Росатома |language=ru}}</ref><ref name="chronology">V. G. Khlopin Radium Institute. [http://www.khlopin.ru/english/hronology.php Chronology] {{Webarchive|url=https://web.archive.org/web/20110426033000/http://www.khlopin.ru/english/hronology.php |date=2011-04-26 }}. Retrieved 25 February 2012.</ref>

The first Asian cyclotron was constructed at the [[Riken]] laboratory in Tokyo, by a team including [[Yoshio Nishina]], Sukeo Watanabe, Tameichi Yasaki, and Ryokichi Sagane. Yasaki and Sagane had been sent to [[Berkeley Radiation Laboratory]] to work with Lawrence. The device had a 26 in diameter and the first beam was produced on April 2, 1937, at 2.9 MeV deuteron energies.<ref name="h349">{{cite journal |last=KIM |first=DONG-WON |date=2006-03-01 |title=Yoshio Nishina and two cyclotrons |journal=Historical Studies in the Physical and Biological Sciences |publisher=University of California Press |volume=36 |issue=2 |pages=243–273 |doi=10.1525/hsps.2006.36.2.243 |issn=0890-9997}}</ref><ref name="x344">{{cite web |date=2024-12-26 |title=Yoshio Nishina |url=https://ahf.nuclearmuseum.org/ahf/profile/yoshio-nishina/ |access-date=2024-12-26 |website=Nuclear Museum}}</ref>