Fixed-field alternating gradient accelerator: Difference between revisions

Revision as of 19:03, 7 October 2020

Revision as of 18:00, 10 December 2020

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| date = Mar 2006

| url = http://www.bnl.gov/isd/documents/31130.pdf

}}</ref><ref>{{cite journal | author=Daniel Clery | date=4 January 2010 | title=The Next Big Beam? | journal=[[Science (journal)|Science]] | volume=327 |pages=142–143 | doi=10.1126/science.327.5962.142 | pmid=20056871 | bibcode = 2010Sci...327..142C | issue=5962 | url = | format = | accessdate = }}</ref> Thus, FFA accelerators combine the cyclotron's advantage of continuous, unpulsed operation, with the synchrotron's relatively inexpensive small magnet ring, of narrow bore.

Although the development of FFAs had not been pursued for over a decade starting from 1967, interest has been revived since the mid-1980s for usage in [[neutron]] [[spallation]] sources, as a driver for [[muon]] colliders <ref name=briefhistory /> and to accelerate muons in a [[Neutrino Factory|neutrino factory]] since the mid-1990s.

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===First development phase===

[[File:MichiganFFAGmark1.jpg|thumb|The Michigan Mark I FFA accelerator. This 400KeV electron accelerator was the first operational FFA accelerator. The large rectangular part on the right is the [[betatron]] transformer core.]]

The idea of fixed-field alternating-gradient synchrotrons was developed independently in Japan by [[Tihiro Ohkawa]], in the United States by [[Keith Symon]], and in Russia by [[Andrei Kolomensky]]. The first prototype, built by [[Lawrence W. Jones]] and [[Kent M. Terwilliger]] at the [[University of Michigan]] used [[betatron]] acceleration and was operational in early 1956.<ref>Lawrence W. Jones, Kent M. Terwilliger, [http://inspirehep.net/record/38999/files/MURA-104.pdf A Small Model Fixed Field Alternating Gradient Radial Sector Accelerator], Technical Report MURA-LWJ/KMT-5 (MURA-104), April 3, 1956; contains photos, scale drawings and design calculations.</ref> That fall, the prototype was moved to the [[Midwestern Universities Research Association]] (MURA) lab at [[University of Wisconsin]], where it was converted to a 500&nbsp;keV electron [[synchrotron]].<ref name=JonesTerwilliger>{{Cite book | last1 = Jones | first1 = L. W. | chapter = Kent M. Terwilliger; graduate school at Berkeley and early years at Michigan, 1949–1959| title = Kent M. Terwilliger memorial symposium, 13−14 Oct 1989| series = [[AIP Conference Proceedings]] | doi = 10.1063/1.41146 | volume = 237 | pages = 1–21| year = 1991 | pmid = | pmc = | hdl = 2027.42/87537 }}</ref> Symon's patent, filed in early 1956, uses the terms "FFAG accelerator" and "FFAG synchrotron".<ref>{{US patent reference

| number = 2932797

| y = 1960

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| inventor = [[Keith Symon|Keith R. Symon]]

| title = [http://www.google.com/patents?id=ZGZVAAAAEBAJ Imparting Energy to Charged Particles]

}}</ref> Ohkawa worked with Symon and the [[Midwestern Universities Research Association|MURA]] team for several years starting in 1955.<ref>{{Cite journal | last1 = Jones | first1 = L. W. | authorlink1author-link1 = Lawrence W. Jones| last2 = Sessler | first2 = A. M. | last3 = Symon | first3 = K. R. | doi = 10.1126/science.316.5831.1567 | title = A Brief History of the FFAG Accelerator | journal = [[Science (journal)|Science]] | volume = 316 | issue = 5831 | pages = 1567 | year = 2007 | pmid = 17569845| pmc = }}</ref>

[[Donald Kerst]], working with Symon, filed a patent for the spiral-sector FFA accelerator at around the same time as Symon's Radial Sector patent.<ref>{{US patent reference

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[[File:aspun.jpg|thumb|ASPUN ring (scaling FFA). The first ANL design ASPUN was a spiral machine designed to increase momentum threefold with a modest spiral as compared with the MURA machines.<ref>{{cite journal|title=ASPUN, Design for an Argonne Super Intense Pulsed Neutron Source|last1=Khoe|first1=T.K.|last2=Kustom|first2=R.L.|volume=30|issue=4|pages=2086–2088|journal=IEEE Transactions on Nuclear Science|date=August 1983|doi=10.1109/tns.1983.4332724|bibcode=1983ITNS...30.2086K|url=https://digital.library.unt.edu/ark:/67531/metadc1108437/|issn=0891-9356|citeseerx=10.1.1.609.1789}}</ref>]]

[[File:PhilM3-Gode.pdf|thumb|Example of a 16-cell superconducting FFA. Energy: 1.6 GeV, average radius 26 m.]]

In the early 1980s, it was suggested by Phil Meads that an FFA was suitable and advantageous as a proton accelerator for an [[Spallation#Production of neutrons at a spallation neutron source|intense spallation neutron source]],<ref>{{cite journal|title=An FFA Compressor and Accelerator Ring Studied for the German Spallation Neutron Source|last1=Meads|first1=P.|last2=Wüstefeld|first2=G.|volume=32|issue=5 (part II)|pages=2697–2699|journal=IEEE Transactions on Nuclear Science|date=October 1985|bibcode=1985ITNS...32.2697M|doi=10.1109/TNS.1985.4334153}}</ref> starting off projects like the Argonne Tandem Linear Accelerator at [[Argonne National Laboratory]]<ref>{{cite web |title = Argonne History: Understanding the Physical Universe |publisher = Argonne National Laboratory |url = http://www.anl.gov/Science_and_Technology/History/Anniversary_Frontiers/physhist.html#neutrino|url-status=dead|archiveurlarchive-url=https://web.archive.org/web/20040909173546/http://www.anl.gov/Science_and_Technology/History/Anniversary_Frontiers/physhist.html|archivedatearchive-date=9 September 2004}}</ref> and the Cooler [[Synchrotron]] at [[Jülich Research Centre]].<ref>{{cite web|url=http://www.fz-juelich.de/ikp/EN/Forschung/Beschleuniger/_doc/COSY.html|title=COSY - Fundamental research in the field of hadron, particle, and nuclear physics|publisher= Institute for Nuclear Physics|accessdateaccess-date=12 February 2017}}</ref>

Conferences exploring this possibility were held at Jülich Research Centre, starting from 1984.<ref>{{cite web|url=http://jdsweb.jinr.ru/record/38097|title= 2nd Jülich Seminar on Fixed Field Alternating Gradient Accelerators (FFA)|___location=[[Jülich]]|last=Wüstefeld|first=G.|date=14 May 1984|accessdateaccess-date=12 February 2017}}</ref> There have also been numerous annual [[Academic conference|workshops]] focusing on FFA accelerators<ref>{{cite journal|url=http://accelconf.web.cern.ch/AccelConf/p05/papers/foac003.pdf|title=New Concepts in FFAG Design for Secondary Beam Facilities and Other Applications|journal=21St Particle Accelerator Conference (Pac 05)|pages=261|first=M.K.|last=Craddock|year=2005|accessdateaccess-date=12 February 2012|bibcode=2005pac..conf..261C}}</ref> at [[CERN]], [[The High Energy Accelerator Research Organization|KEK]], [[Brookhaven National Laboratory|BNL]], [[TRIUMF]], [[Fermilab]], and the Reactor Research Institute at [[Kyoto University]].<ref>{{cite web|url=https://www.bnl.gov/ffag14/pastWorkshops.php|title=Previous Workshops|publisher=[[Brookhaven National Laboratory|BNL]]|accessdateaccess-date=12 February 2017}}</ref> In 1992, the European Particle Accelerator Conference at CERN was about FFA accelerators.<ref name=FFAGopts>{{Cite journal

| first1 = S. | last1 = Martin

| first2 = P. | last2 = Meads

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}}</ref><ref>{{cite journal|title=Fourth Accelerator Meeting for the EPNS|journal=European Particle Accelerator Conference|date=24 March 1992|first=E.|last=Zaplatin}}</ref>

The first proton FFA was successfully construction in 2000,<ref>{{cite journal|author=M. Aiba|display-authors=etal|title= Development of a FFAG Proton Synchrotron|journal=European Particle Accelerator Conference|year=2000|access-date=}}</ref> initiating a boom of FFA activities in [[Particle physics|high-energy physics]] and [[medicine]].

With [[superconducting magnets]], the required length of the FFA magnets scales roughly as the inverse square of the magnetic field.<ref name=mewu>{{Cite journal

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The MURA machines were scaling FFA synchrotrons meaning that orbits of any momentum are photographic enlargements of those of any other momentum. In such machines the betatron frequencies are constant, thus no resonances, that could lead to beam loss,<ref>

{{Cite book

|last1=Livingston |first1=M. S. | authorlink1author-link1 = Milton Stanley Livingston

|last2=Blewett |first2=J.

|year=1962

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==Further reading==

* {{cite magazine | magazine = CERN Courier | title = The rebirth of the FFAG | url = http://cerncourier.com/cws/article/cern/29119 | date = Jul 28, 2004 | accessdateaccess-date = Apr 11, 2012 }}

==References==