Editing Super Proton Synchrotron

{{Short description|Particle accelerator at CERN, Switzerland}}
{{Use dmy dates|date=August 2024}}
{{Infobox particle accelerator
| name           = Super Proton Synchrotron
| image          = Beamfeedingams.JPG
| caption        = Test beamline delivered from the SPS. In photo 20 GeV positrons are used to calibrate the [[Alpha Magnetic Spectrometer]].
| type           = [[Synchrotron]]
| beam           = [[proton]]s, heavy ions
| target         = Injector for [[Large Hadron Collider|LHC]], fixed target
| energy         = 450 GeV
| current        = 
| brightness     =
| luminosity     =
| length         =
| radius         =
| circumference  = {{convert|6.9|km|mi}}
| location       =
| coordinates    = {{coord|46|14|06|N|6|02|33|E|region:CH_type:landmark|display=inline, title}}
| institution    = [[CERN]]
| dates          = 1976–present
| preceded       = [[Proton-Antiproton Collider|Sp{{overline|p}}S]]
| succeeded      = 
}}
{{CERNaccelerators}}
The '''Super Proton Synchrotron''' ('''SPS''') is a [[particle accelerator]] of the [[synchrotron]] type at [[CERN]]. It is housed in a circular tunnel, {{convert|6.9|km|mi}} in circumference,<ref>{{Cite web |url=http://ab-dep-op-sps.web.cern.ch/ab-dep-op-sps/SPS_Presentation.htm |title=SPS Presentation at AB-OP-SPS Home Page |access-date=2008-09-15 |archive-date=2011-10-05 |archive-url=https://web.archive.org/web/20111005040903/http://ab-dep-op-sps.web.cern.ch/ab-dep-op-sps/SPS_Presentation.htm |url-status=dead }}</ref> straddling the border of France and Switzerland near [[Geneva]], Switzerland.<ref>[http://building.web.cern.ch/building/ Information on CERN Sites] {{Webarchive|url=https://archive.today/20120708071016/http://building.web.cern.ch/building/ |date=8 July 2012 }}. [[CERN]]. Updated 26 January 2010.</ref>

==History==
[[File:CERN UA5 - ppbar interaction at 540GeV.jpg|thumb|A [[proton]]&ndash;[[antiproton]] collision from the [[UA5 experiment]] at the SPS in 1982]]
The SPS was designed by a team led by [[John Adams (physicist)|John Adams]], [[List of Directors General of CERN|director-general]] of what was then known as [[Laboratory II]]. Originally specified as a 300 [[GeV]] accelerator, the SPS was actually built to be capable of 400&nbsp;GeV, an operating energy it achieved on the official commissioning date of 17 June 1976. However, by that time, this energy had been exceeded by [[Fermilab]], which reached an energy of 500&nbsp;GeV on 14 May of that year.<ref>[http://cerncourier.com/cws/article/cern/28470 CERN courier]</ref>

The SPS has been used to accelerate [[proton]]s and [[antiproton]]s, [[electron]]s and [[positron]]s (for use as the injector for the [[Large Electron–Positron Collider]] (LEP)<ref>[http://sl-div.web.cern.ch/sl-div/history/lep_doc.html#3.8 The LEP Collider – from Design to Approval and Commissioning] {{Webarchive|url=https://web.archive.org/web/20140618030149/https://sl-div.web.cern.ch/sl-div/history/lep_doc.html#3.8 |date=18 June 2014 }}, by S. Myers, section 3.8. Last accessed 28 February 2010.</ref>), and [[quark–gluon plasma|heavy ions]].

From 1981 to 1991, the SPS operated as a hadron (more precisely, proton–antiproton) collider (as such it was called [[Proton-Antiproton Collider|Sp{{overline|p}}S)]], when its beams provided the data for the [[UA1 experiment|UA1]] and [[UA2 experiment]]s, which resulted in the discovery of the [[W and Z bosons]]. These discoveries and a new technique for [[stochastic cooling|cooling]] particles led to a Nobel Prize for [[Carlo Rubbia]] and [[Simon van der Meer]] in 1984.

From 2006 to 2012, the SPS was used by the [[CERN Neutrinos to Gran Sasso|CNGS]] experiment to produce a [[neutrino]] [[Accelerator neutrino|beam]] to be detected at the [[Laboratori Nazionali del Gran Sasso|Gran Sasso]] laboratory in Italy, 730&nbsp;km from CERN.

==Later operations==
{{See also|List of Super Proton Synchrotron experiments}}
The SPS is used as the final injector for high-intensity proton beams for the [[Large Hadron Collider]] (LHC), which began preliminary operation on 10 September 2008, for which it accelerates protons from 26&nbsp;GeV to 450&nbsp;GeV. The LHC itself then accelerates them to several [[teraelectronvolt]]s (TeV).

Operation as an injector allows continuation of the ongoing [[fixed-target experiment|fixed-target]] research program, where the SPS provides 400&nbsp;GeV proton beams for a number of active fixed-target experiments, including [[COMPASS experiment|COMPASS]], [[NA61/SHINE]] and [[NA62 experiment|NA62]].

The SPS has served, and continues to be used as a test bench for new concepts in accelerator physics. In 1999 it served as an observatory for the [[Electron-cloud effect|electron cloud phenomenon]].<ref>{{Cite web |url=http://accelconf.web.cern.ch/AccelConf/e00/PAPERS/THP1B16.pdf |title=observation of e-cloud |access-date=2006-07-20 |archive-date=2011-09-29 |archive-url=https://web.archive.org/web/20110929120558/http://accelconf.web.cern.ch/AccelConf/e00/PAPERS/THP1B16.pdf |url-status=dead }}</ref> In 2002 and 2004, SPS produced [[gold]] nuclei from [[lead]] targets.<ref name="Cecchini et al 2002">{{cite journal | last=Cecchini | first=S. | last2=Giacomelli | first2=G. | last3=Giorgini | first3=M. | last4=Mandrioli | first4=G. | last5=Patrizii | first5=L. | last6=Popa | first6=V. | last7=Serra | first7=P. | last8=Sirri | first8=G. | last9=Spurio | first9=M. | title=Fragmentation cross sections of 158AGeV Pb ions in various targets measured with CR39 nuclear track detectors | journal=Nuclear Physics A | volume=707 | issue=3-4 | date=2002 | doi=10.1016/S0375-9474(02)00962-4 | doi-access=free | pages=513–524 | url=https://arxiv.org/pdf/hep-ex/0201039 | access-date=May 13, 2025| arxiv=hep-ex/0201039 }}</ref><ref name="Scheidenberger et al 2004">{{cite journal | last=Scheidenberger | first=C. | last2=Pshenichnov | first2=I. A. | last3=Sümmerer | first3=K. | last4=Ventura | first4=A. | last5=Bondorf | first5=J. P. | last6=Botvina | first6=A. S. | last7=Mishustin | first7=I. N. | last8=Boutin | first8=D. | last9=Datz | first9=S. | last10=Geissel | first10=H. | last11=Grafström | first11=P. | last12=Knudsen | first12=H. | last13=Krause | first13=H. F. | last14=Lommel | first14=B. | last15=Møller | first15=S. P. | last16=Münzenberg | first16=G. | last17=Schuch | first17=R. H. | last18=Uggerhøj | first18=E. | last19=Uggerhøj | first19=U. | last20=Vane | first20=C. R. | last21=Vilakazi | first21=Z. Z. | last22=Weick | first22=H. | title=Charge-changing interactions of ultrarelativistic Pb nuclei | journal=Physical Review C | volume=70 | issue=1 | date=July 29, 2004 | issn=0556-2813 | doi=10.1103/PhysRevC.70.014902 | doi-access=free | url=http://cds.cern.ch/record/971196/files/PhysRevC.70.014902.pdf | access-date=May 13, 2025 }}</ref><ref name="CERN press release 2025">{{cite web | title=ALICE detects the conversion of lead into gold at the LHC | website=CERN | date=May 8, 2025 | url=https://home.cern/news/news/physics/alice-detects-conversion-lead-gold-lhc | access-date=May 13, 2025}}</ref> In 2003, SPS was the first machine where the [[Hamiltonian resonance]] driving terms were directly measured.<ref>[http://www.tdx.cesca.es/TESIS_UV/AVAILABLE/TDX-0219104-131907//rogelio.pdf Measurement of resonance driving terms] {{Webarchive|url=https://web.archive.org/web/20110716173944/http://www.tdx.cesca.es/TESIS_UV/AVAILABLE/TDX-0219104-131907//rogelio.pdf |date=16 July 2011 }}</ref> And in 2004, experiments to cancel the detrimental effects of beam encounters (like those in the LHC) were carried out.<ref>{{Cite web |url=http://accelconf.web.cern.ch/AccelConf/e04/PAPERS/WEPLT045.PDF |title=wire compensation |access-date=2006-07-24 |archive-date=2011-09-29 |archive-url=https://web.archive.org/web/20110929120623/http://accelconf.web.cern.ch/AccelConf/e04/PAPERS/WEPLT045.PDF |url-status=dead }}</ref>

The SPS [[superconducting radio frequency|RF cavities]] operate at a center frequency of 200.2 [[megahertz|MHz]].

==Major discoveries==
Major scientific discoveries made by experiments that operated at the SPS include the following.

*1983: The discovery of [[W and Z bosons]] in the [[UA1 experiment|UA1]] and [[UA2 experiment]]s.<ref name="wz">{{cite web |title=CERN.ch La |url=https://timeline.web.cern.ch/discovery-w-particle |access-date=20 November 2010 |publisher=Public.web.cern.ch}}</ref> The 1984 [[Nobel Prize for Physics|Nobel Prize in physics]] was awarded to [[Carlo Rubbia]] and [[Simon van der Meer]] for the developments that led to this discovery.
*1999: The discovery of direct [[CP violation]] by the [[NA48 experiment]].<ref name="NA48">{{cite journal |last1=Fanti |first1=V. |title=A new measurement of direct CP violation in two pion decays of the neutral kaon|journal=[[Physics Letters B]] |volume=465 |issue=1–4 |pages=335–348 |year=1999 |arxiv=hep-ex/9909022 |bibcode = 1999PhLB..465..335F |doi = 10.1016/S0370-2693(99)01030-8 |display-authors=1 |last2=Lai |first2=A. |last3=Marras |first3=D. |last4=Musa |first4=L. |last5=Bevan |first5=A.J. |last6=Gershon |first6=T.J. |last7=Hay |first7=B. |last8=Moore |first8=R.W. |last9=Moore |first9=K.N.|s2cid=15277360 }}</ref>

==Upgrade for high luminosity LHC==
The [[Large Hadron Collider]] will require [[High Luminosity Large Hadron Collider|an upgrade]] to considerably increase its [[luminosity (scattering theory)|luminosity]] during the 2020s. This would require upgrades to the entire linac/pre-injector/injector chain, including the SPS.

As part of this, the SPS will need to be able to handle a much higher intensity beam. One improvement considered in the past was increasing the extraction energy to 1&nbsp;TeV.<ref>[http://paf.web.cern.ch/paf/Presentations/PAF_15Sep05-Scandale-INJ-highlights.pdf Super-SPS]</ref> However, the extraction energy will be kept at 450 GeV while other systems are upgraded. The [[Microwave cavity|acceleration system]] will be modified to handle the higher voltages needed to accelerate a higher intensity beam. The beam dumping system will also be upgraded so it can accept a higher intensity beam without sustaining significant damage.<ref>{{Cite journal |last1=Hanke |first1=Klaus |last2=Damerau |first2=Heiko |last3=Deleu |first3=Axelle |last4=Funken |first4=Anne |last5=Garoby |first5=Roland |last6=Gilardoni |first6=Simone |last7=Gilbert |first7=Nicolas |last8=Goddard |first8=Brennan |last9=Holzer |first9=Eva Barbara |last10=Lombardi |first10=Alessandra |last11=Manglunki |first11=Django |last12=Meddahi |first12=Malika |last13=Mikulec |first13=Bettina |last14=Shaposhnikova |first14=Elena |last15=Vretenar |first15=Maurizio |date=2014 |others=Petit-Jean-Genaz Christine (Ed.), Arduini Gianluigi (Ed.), Michel Peter (Ed.), Schaa, Volker RW (Ed.) |title=Status of the LIU Project at CERN |url=http://jacow.org/IPAC2014/doi/JACoW-IPAC2014-THPME070.html |journal=Proceedings of the 5th Int. Particle Accelerator Conf. |language=en |volume=IPAC2014 |pages=3 pages, 0.320 MB |doi=10.18429/JACOW-IPAC2014-THPME070}}</ref>

==Notes and references==
{{Reflist}}

==External links==
*{{Commons category-inline}}
*[https://inspirehep.net/experiments/1607946 SPS experiment record] on [[INSPIRE-HEP]]

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{{Hadron colliders}}

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