The Super Proton Synchrotron (SPS) is a

particle accelerator A particle accelerator is a machine that uses electromagnetic fields to propel charged particles to very high speeds and energies, and to contain them in well-defined beams. Large accelerators are used for fundamental research in particle ...

of the

synchrotron A synchrotron is a particular type of cyclic particle accelerator, descended from the cyclotron, in which the accelerating particle beam travels around a fixed closed-loop path. The magnetic field which bends the particle beam into its closed p ...

type at

CERN The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in a northwestern suburb of Gene ...

. It is housed in a circular tunnel, in circumference, straddling the border of France and Switzerland near

Geneva Geneva ( ; french: Genève ) frp, Genèva ; german: link=no, Genf ; it, Ginevra ; rm, Genevra is the List of cities in Switzerland, second-most populous city in Switzerland (after Zürich) and the most populous city of Romandy, the French-speaki ...

, Switzerland.

History

The SPS was designed by a team led by

John Adams John Adams (October 30, 1735 – July 4, 1826) was an American statesman, attorney, diplomat, writer, and Founding Fathers of the United States, Founding Father who served as the second president of the United States from 1797 to 1801. Befor ...

director-general A director general or director-general (plural: ''directors general'', ''directors-general'', ''director generals'' or ''director-generals'' ) or general director is a senior executive officer, often the chief executive officer, within a government ...

of what was then known as Laboratory II. Originally specified as a 300

GeV GEV may refer to: * ''G.E.V.'' (board game), a tabletop game by Steve Jackson Games * Ashe County Airport, in North Carolina, United States * Gällivare Lapland Airport, in Sweden * Generalized extreme value distribution * Gev Sella, Israeli-Sou ...

accelerator, the SPS was actually built to be capable of 400 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 Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a United States Department of Energy national laboratory specializing in high-energy particle physics. Since 2007, Fermilab has been operat ...

, which reached an energy of 500 GeV on 14 May of that year. The SPS has been used to accelerate

proton A proton is a stable subatomic particle, symbol , H+, or 1H+ with a positive electric charge of +1 ''e'' elementary charge. Its mass is slightly less than that of a neutron and 1,836 times the mass of an electron (the proton–electron mass ...

s and

antiproton The antiproton, , (pronounced ''p-bar'') is the antiparticle of the proton. Antiprotons are stable, but they are typically short-lived, since any collision with a proton will cause both particles to be annihilated in a burst of energy. The exis ...

electron The electron ( or ) is a subatomic particle with a negative one elementary electric charge. Electrons belong to the first generation of the lepton particle family, and are generally thought to be elementary particles because they have no kn ...

s and

positron The positron or antielectron is the antiparticle or the antimatter counterpart of the electron. It has an electric charge of +1 '' e'', a spin of 1/2 (the same as the electron), and the same mass as an electron. When a positron collides ...

s (for use as the injector for the

Large Electron–Positron Collider The Large Electron–Positron Collider (LEP) was one of the largest particle accelerators ever constructed. It was built at CERN, a multi-national centre for research in nuclear and particle physics near Geneva, Switzerland. LEP collided electr ...

(LEP)), and

heavy ions Heavy may refer to: Measures * Heavy (aeronautics), a term used by pilots and air traffic controllers to refer to aircraft capable of 300,000 lbs or more takeoff weight * Heavy, a characterization of objects with substantial weight * Heavy, ...

. From 1981 to 1991, the SPS operated as a hadron (more precisely, proton–antiproton) collider (as such it was called SpS), when its beams provided the data for the

UA1 The UA1 experiment (an abbreviation of Underground Area 1) was a high-energy physics experiment that ran at CERN's Proton-Antiproton Collider (SpS), a modification of the one-beam Super Proton Synchrotron (SPS). The data was recorded between 198 ...

and

UA2 experiment The Underground Area 2 (UA2) experiment was a high-energy physics experiment at the Proton-Antiproton Collider (SpS) — a modification of the Super Proton Synchrotron (SPS) — at CERN. The experiment ran from 1981 until 1990, and its main object ...

s, which resulted in the discovery of the

W and Z bosons In particle physics, the W and Z bosons are vector bosons that are together known as the weak bosons or more generally as the intermediate vector bosons. These elementary particles mediate the weak interaction; the respective symbols are , , and ...

. These discoveries and a new technique for

cooling Cooling is removal of heat, usually resulting in a lower temperature and/or phase change. Temperature lowering achieved by any other means may also be called cooling.ASHRAE Terminology, https://www.ashrae.org/technical-resources/free-resources/as ...

particles led to a

Nobel Prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...

for

Carlo Rubbia Carlo Rubbia (born 31 March 1934) is an Italian particle physicist and inventor who shared the Nobel Prize in Physics in 1984 with Simon van der Meer for work leading to the discovery of the W and Z particles at CERN. Early life and education ...

and

Simon van der Meer Simon van der Meer (24 November 19254 March 2011) was a Dutch particle accelerator physicist who shared the Nobel Prize in Physics in 1984 with Carlo Rubbia for contributions to the CERN project which led to the discovery of the W and Z part ...

in 1984. From 2006 to 2012, the SPS was used by the CNGS experiment to produce a

neutrino A neutrino ( ; denoted by the Greek letter ) is a fermion (an elementary particle with spin of ) that interacts only via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass ...

stream A stream is a continuous body of water, body of surface water Current (stream), flowing within the stream bed, bed and bank (geography), banks of a channel (geography), channel. Depending on its location or certain characteristics, a stream ...

to be detected at the

Gran Sasso Gran Sasso d'Italia (; ) is a massif in the Apennine Mountains of Italy. Its highest peak, Corno Grande (2,912 metres), is the highest mountain in the Apennines, and the second-highest mountain in Italy outside the Alps. The mountain lies wit ...

laboratory in Italy, 730 km from CERN.

Current operations

The SPS is now used as the final injector for high-intensity proton beams for the

Large Hadron Collider The Large Hadron Collider (LHC) is the world's largest and highest-energy particle collider. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundred ...

(LHC), which began preliminary operation on 10 September 2008, for which it accelerates protons from 26 GeV to 450 GeV. The LHC itself then accelerates them to several

teraelectronvolt In physics, an electronvolt (symbol eV, also written electron-volt and electron volt) is the measure of an amount of kinetic energy gained by a single electron accelerating from rest through an electric potential difference of one volt in vacuum. ...

s (TeV). Operation as injector still allows continuation of the ongoing fixed-target research program, where the SPS is used to provide 400 GeV proton beams for a number of active fixed-target experiments, notably

COMPASS A compass is a device that shows the cardinal directions used for navigation and geographic orientation. It commonly consists of a magnetized needle or other element, such as a compass card or compass rose, which can pivot to align itself with ...

, NA61/SHINE and 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 phenomenon. In 2003, SPS was the first machine where the Hamiltonian resonance driving terms were directly measured. And in 2004, experiments to cancel the detrimental effects of beam encounters (like those in the LHC) were carried out. The SPS RF cavities operate at a center frequency of 200.2

MHz The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. The hertz is an SI derived unit whose expression in terms of SI base units is s−1, meaning that one he ...

Major discoveries

Major scientific discoveries made by experiments that operated at the SPS include the following. *1983: The discovery of

in the

and

s. The 1984

Nobel Prize in physics ) , image = Nobel Prize.png , alt = A golden medallion with an embossed image of a bearded man facing left in profile. To the left of the man is the text "ALFR•" then "NOBEL", and on the right, the text (smaller) "NAT•" then " ...

was awarded to

and

for the developments that led to this discovery. *1999: The discovery of direct

CP violation In particle physics, CP violation is a violation of CP-symmetry (or charge conjugation parity symmetry): the combination of C-symmetry (charge symmetry) and P-symmetry ( parity symmetry). CP-symmetry states that the laws of physics should be the ...

by the

NA48 experiment The NA48 experiment was a series of particle physics experiments in the field of kaon physics being carried out at the North Area of the Super Proton Synchrotron at CERN. The collaboration involved over 100 physicists mostly from Western Europe ...

Upgrade for High Luminosity LHC

The

will require an upgrade to considerably increase its

luminosity Luminosity is an absolute measure of radiated electromagnetic power (light), the radiant power emitted by a light-emitting object over time. In astronomy, luminosity is the total amount of electromagnetic energy emitted per unit of time by a st ...

during the

2020s The 2020s (pronounced "twenty-twenties" shortened to "the '20s" and referred to as the twenties) is the current decade, which began on January 1, 2020, and will end on December 31, 2029. The 2020s began with the COVID-19 pandemic — the first ...

. 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 TeV. However, the extraction energy will be kept at 450 GeV while other systems are upgraded. The 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.http://cds.cern.ch/record/1742199/files/CERN-ACC-2014-0125.pdf

Notes and references

External links

*
SPS experiment record
on

INSPIRE-HEP INSPIRE-HEP is an open access digital library for the field of high energy physics (HEP). It is the successor of the Stanford Physics Information Retrieval System (SPIRES) database, the main literature database for high energy physics since the 1970 ...

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