CERN has come a long way since its foundation in 1954. This timeline collects the organization's major contracts, projects, partnerships and scientific advances.
At the end of the Second World War, European science was no longer world-class. Following the example of international organizations, a handful of visionary scientists imagined creating a European atomic physics laboratory. Raoul Dautry, Pierre Auger and Lew Kowarski in France, Edoardo Amaldi in Italy and Niels Bohr in Denmark were among these pioneers. Such a laboratory would not only unite European scientists but also allow them to share the increasing costs of nuclear physics facilities.
French physicist Louis de Broglie put forward the first official proposal for the creation of a European laboratory at the European Cultural Conference, which opened in Lausanne on 9 December 1949. A further push came at the fifth UNESCO General Conference, held in Florence in June 1950, where American physicist and Nobel laureate Isidor Rabi tabled a resolution authorizing UNESCO to "assist and encourage the formation of regional research laboratories in order to increase international scientific collaboration…"
At an intergovernmental meeting of UNESCO in Paris in December 1951, the first resolution concerning the establishment of a European Council for Nuclear Research was adopted. Two months later, 11 countries signed an agreement establishing the provisional council – the acronym CERN was born.
Geneva was selected as the site for the CERN Laboratory at the third session of the provisional council in 1952. This selection successfully passed a referendum in the canton of Geneva in June 1953 by 16,539 votes to 7332.
On 17 May 1954, the first shovel of earth was dug on the Meyrin site in Switzerland under the eyes of Geneva officials and members of CERN staff.
At the sixth session of the CERN Council, which took place in Paris from 29 June - 1 July 1953, the convention establishing the organization was signed, subject to ratification, by 12 states. The convention was gradually ratified by the 12 founding Member States: Belgium, Denmark, France, the Federal Republic of Germany, Greece, Italy, the Netherlands, Norway, Sweden, Switzerland, the United Kingdom, and Yugoslavia. On 29 September 1954, following ratification by France and Germany, the European Organization for Nuclear Research officially came into being. The provisional CERN was dissolved but the acronym remained.
The 600 MeV Synchrocyclotron (SC), built in 1957, was CERN’s first accelerator. It provided beams for CERN’s first experiments in particle and nuclear physics. In 1964, this machine started to concentrate on nuclear physics alone, leaving particle physics to the newer and much more powerful Proton Synchrotron (PS).
The SC became a remarkably long-lived machine. In 1967, it started supplying beams for a dedicated unstable-ion facility called ISOLDE, which carries out research ranging from pure nuclear physics to astrophysics and medical physics. In 1990, ISOLDE was transferred to a different accelerator, and the SC closed down after 33 years of service.
The Proton Synchrotron (PS) accelerated protons for the first time on 24 November 1959, becoming for a brief period the world’s highest energy particle accelerator. With a beam energy of 28 GeV, the PS became host to CERN’s particle physics programme, and provides beams for experiments to this day.
During the night of 24 November 1959 the PS reached its full energy. The next morning John Adams (pictured) announced the achievement in the main auditorium. In his hand is an empty vodka bottle, which he had received from Dubna with the message that it was to be drunk when CERN passed the Russian Synchrophasotron’s world-record energy of 10 GeV. The bottle contains a polaroid photograph of the 24 GeV pulse ready to be sent back to Dubna.
When CERN built new accelerators in the 1970s, the PS’s principle role became to supply particles to the new machines. Since the PS started up in 1959, the intensity of its proton beam has increased a thousandfold, and the machine has become the world’s most versatile particle juggler.
In the course of its history the PS has accelerated many different kinds of particles, feeding them to more powerful accelerators or directly to experiments.
By 1965, all three particles that make up atoms (electrons, protons and neutrons) were known to each have an antiparticle. So if particles, bound together in atoms, are the basic units of matter, it is natural to think that antiparticles, bound together in antiatoms, are the basic units of antimatter.
But are matter and antimatter exactly equal and opposite, or symmetric, as Dirac had implied? The next important step was to test this symmetry. Physicists wanted to know how subatomic antiparticles behave when they come together. Would an antiproton and an antineutron stick together to form an antinucleus, just as protons and neutrons stick together to form the nucleus of an atom?
The answer to the antinuclei question was found in 1965 with the observation of the antideuteron, a nucleus of antimatter made out of an antiproton plus an antineutron (while a deuteron – the nucleus of the deuterium atom – is made of a proton plus a neutron). The goal was simultaneously achieved by two teams of physicists, one led by Antonino Zichichi using the Proton Synchrotron at CERN, and the other led by Leon Lederman, using the Alternating Gradient Synchrotron (AGS) accelerator at the Brookhaven National Laboratory, New York.
The CERN paper, Experimental Observation of Antideuteron Production was published in the Italian particle-physics journal Il nuovo cimento on 1 September 1965 (the journal ended when it was merged into the European Physical Journal in 1999.
In the 1960s, detection in particle physics mainly involved examining millions of photographs from bubble chambers or spark chambers. This was slow, labour-intensive and unsuitable for studies into rare phenomena.
Then came a revolution in transistor amplifiers. While a camera can detect a spark, a detector wire connected to an amplifier can detect a much smaller effect. In 1968, Georges Charpak developed the “multiwire proportional chamber”, a gas-filled box with a large number of parallel detector wires, each connected to individual amplifiers. Linked to a computer, it could achieve a counting rate a thousand times better than existing detectors. The invention revolutionized particle detection, which passed from the manual to the electronic era.
Charpak, who joined CERN in 1959, was awarded the 1992 Nobel prize in physics "for his invention and development of particle detectors, in particular the multiwire proportional chamber".
Today practically every experiment in particle physics uses some track detector based on the principle of the multiwire proportional chamber. Charpak has also actively contributed to the use of this technology in other fields that use ionizing radiation such as biology, radiology and nuclear medicine.
By the late 1950s, physicists knew that a huge gain in collision energy would come from colliding particle beams head on, rather than by using a single beam and a stationary target. At CERN, accelerator experts conceived the idea to use the Proton Synchrotron (PS) to feed two interconnected rings where two intense proton beams could be built up and then made to collide. The project for the Intersecting Storage Rings (ISR) was formally approved in 1965.
On 27 January 1971 Kjell Johnsen (pictured), who led the construction team for the Intersecting Storage Rings (ISR), announced that the world's first interactions from colliding protons had been recorded. Pictured on the left are Franco Bonaudi, who was responsible for the civil engineering and Dirk Neet, who later took charge of ISR operations.
For the next 13 years the machine provided a unique view of the minuscule world of particle physics. It also allowed CERN to gain valuable knowledge and expertise for subsequent colliding-beam projects, and ultimately the Large Hadron Collider. For example, it was here that Simon van der Meer’s ideas to produce intense beams by a process called "stochastic cooling" were first demonstrated.
Seven kilometres in circumference, the Super Proton Synchrotron (SPS) was the first of CERN’s giant underground rings. It was also the first accelerator to cross the Franco–Swiss border.
Eleven of CERN's member states approved the construction of the SPS in February 1971, and it was switched on for the first time on 17 June 1976, two years ahead of schedule. The SPS quickly became the workhorse of CERN’s particle physics programme, providing beams to two large experimental areas. Advances in technology during the building period meant that not only was construction finished early, it was able to operate with a beam energy of 400 GeV - 100 GeV higher than the original design energy.
The SPS operates today at up to 450 GeV, and has handled many different kinds of particles. Research using SPS beams has probed the inner structure of protons, investigated nature’s preference for matter over antimatter, looked for matter as it might have been in the first instants of the universe and searched for exotic forms of matter.
A few months after the signature of the agreement giving the go-ahead for the expansion of CERN into French territory, work began on the Super Proton Synchrotron (SPS). Two years later, on 31 July 1974, the Robbins tunnel-boring machine excavating the SPS tunnel returned to its starting point (see photograph). It had excavated a tunnel with a circumference of 7 kilometres, at an average depth of 40 metres below the surface. The tunnel straddled the Franco-Swiss border, making the SPS the first cross-border accelerator. More than a thousand magnets were needed to equip the ring. The civil engineering and installation work was completed in record time after only four years.
The Super Proton Synchrotron (SPS) became the workhorse of CERN’s particle physics programme when it switched on in 1976. The first beam of protons circulated the full 7 kilometres of the accelerator on 3 May 1976. The picture above shows the SPS control room on 17 June 1976, when the machine accelerated protons to 400 GeV for the first time. Research using SPS beams has probed the inner structure of protons, investigated nature’s preference for matter over antimatter, looked for matter as it might have been in the first instants of the universe and searched for exotic forms of matter. A major highlight came in 1983 with the Nobel-prize-winning discovery of W and Z particles, with the SPS running as a proton-antiproton collider.
The SPS operates at up to 450 GeV. It has 1317 conventional (room-temperature) electromagnets, including 744 dipoles to bend the beams round the ring. The accelerator has handled many different kinds of particles: sulphur and oxygen nuclei, electrons, positrons, protons and antiprotons.
The Intersecting Storage Rings produced the world’s first proton-antiproton collisions on 4 April 1981, paving the way for proton-antiproton collisions in the Super Proton Synchrotron (SPS), and the Nobel prize for Simon van der Meer and Carlo Rubbia.
The ISR proved to be an excellent instrument for particle physics. By the time the machine closed down in 1984, it had produced many important results, including indications that protons contain smaller constituents, ultimately identified as quarks and gluons.
In 1979, CERN decided to convert the Super Proton Synchrotron (SPS) into a proton–antiproton collider. A technique called stochastic cooling was vital to the project's success as it allowed enough antiprotons to be collected to make a beam.
The first proton–antiproton collisions were achieved just two years after the project was approved, and two experiments, UA1 and UA2, started to search the collision debris for signs of W and Z particles, carriers of the weak interaction between particles.
In 1983, CERN announced the discovery of the W and Z particles.The image above shows the the first detection of a Z0 particle, as seen by the UA1 experiment on 30 April 1983. The Z0 itself decays very quickly so cannot be seen, but an electron-proton pair produced in the decay appear in blue. UA1 observed proton-antiproton collisions on the SPS between 1981 and 1993 to look for the Z and W bosons, which mediate the weak fundamental force.
Carlo Rubbia and Simon van der Meer, key scientists behind the work, received the Nobel Prize in physics only a year after the discovery. Rubbia instigated conversion of the SPS accelerator into a proton-antiproton collider and was spokesperson of the UA1 experiment while Van der Meer invented the stochastic cooling technique vital to the collider’s operation.
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Just after the big bang the universe was too hot and dense for the existence of familiar particles such as protons and neutrons. Instead, their constituents – the quarks and gluons – roamed freely in a "particle soup" called quark-gluon plasma.
In 1986 CERN began to accelerate heavy ions – nuclei containing many neutrons and protons – in the Super Proton Synchrotron (SPS) to study the possibility that quark gluon-plasma was more than just a theory. The aim was to "deconfine" quarks – set them free from their confinement within atoms - by smashing the heavy ions into appropriate targets.
The first experiments used relatively light nuclei such as oxygen and sulphur, and produced results consistent with the quark-gluon plasma theory, but no real proof. In 1994 a second generation of experiments began with lead ions, and by 2000 there was compelling evidence that a new state of matter had been seen.
The excavation of the tunnel for the Large Electron-Positron Collider – Europe’s largest civil-engineering project prior to the Channel Tunnel – was completed on 8 February 1988. The two ends of the 27-kilometre ring came together with just one centimetre of error. The picture above shows a tunneling crew after completing a section of the tunnel between points 2 and 3 on the LEP ring.
With its 27-kilometre circumference, the Large Electron-Positron (LEP) collider was – and still is – the largest electron-positron accelerator ever built. LEP consisted of 5176 magnets and 128 accelerating cavities. CERN’s accelerator complex provided the particles and four enormous detectors, ALEPH, DELPHI, L3 and OPAL, observed the collisions.
LEP was commissioned in July 1989 and the first beam circulated in the collider on 14 July. The picture above shows physicists grouped around a screen in the LEP control room at the moment of start-up. Carlo Rubbia, Director-General of CERN at the time, is in the centre and former Director-General Herwig Schopper is on his left. For seven years, the accelerator operated at 100 GeV, producing 17 million Z particles, uncharged carriers of the weak force. It was then upgraded for a second operation phase, with as many as 288 superconducting accelerating cavities added to double the energy and produce W bosons, also carriers of the weak force. LEP collider energy eventually topped 209 GeV in the year 2000.
During 11 years of research, LEP and its experiments provided a detailed study of the electroweak interaction based on solid experimental foundations. Measurements performed at LEP also proved that there are three – and only three – generations of particles of matter. LEP was closed down on 2 November 2000 to make way for the construction of the LHC in the same tunnel.
By Christmas 1990, Berners-Lee had defined the Web’s basic concepts, the URL, http and html, and he had written the first browser and server software. Info.cern.ch was the address of the world's first website and web server, running on a NeXT computer at CERN. The world's first web page address was http://info.cern.ch/hypertext/WWW/TheProject.html, which centred on information regarding the WWW project. Visitors could learn more about hypertext, technical details for creating their own webpage, and even an explanation on how to search the Web for information. There are no screenshots of this original page and, in any case, changes were made daily to the information available on the page as the WWW project developed. You may find a later copy (1992) on the World Wide Web Consortium website.
You can see the orginal NeXT computer at the Microcosm exhibit at CERN, still bearing the label, hand-written in red ink: "This machine is a server. DO NOT POWER DOWN!!"
A team led by Walter Oelert created atoms of antihydrogen for the first time at CERN’s Low Energy Antiproton Ring (LEAR) facility. Nine of these atoms were produced in collisions between antiprotons and xenon atoms over a period of 3 weeks. Each one remained in existence for about 40 billionths of a second, travelled at nearly the speed of light over a path of 10 metres and then annihilated with ordinary matter. The annihilation produced the signal that showed that the anti-atoms had been created.
This was the first time that antimatter particles had been brought together to make complete atoms, and the first step in a programme to make detailed measurements of antihydrogen.
The hydrogen atom is the simplest atom of all, made of a single proton orbited by an electron. Some three quarters of all the ordinary matter in the universe is hydrogen, and the hydrogen atom is one of the best understood systems in physics. Comparison with antihydrogen offers a route to understanding the matter–antimatter asymmetry in the universe.
Four years after the first technical proposals, the experiments CMS and ATLAS were officially approved. Both experiments seek the Higgs boson, the particle which provides a mechanism to explain particle mass.
In 1996 CERN's antiproton machines – the Antiproton Accumulator (AC), the Antiproton Collector and the Low Energy Antiproton Ring (LEAR) – were closed down to free resources for the Large Hadron Collider. But a community of antimatter scientists wanted to continue their LEAR experiments with slow antiprotons. Council asked the Proton Synchrotron division to investigate a low-cost way to provide the necessary low-energy beams.
The resulting design report for the Antiproton Decelerator concluded:
The use of the Antiproton Collector as an antiproton decelerator holds the promise of delivering dense beams of 107 protons per minutes and low energy (100 MeV/c) with bunch lengths down to 200 nanoseconds.
The use of the Antiproton Collector as an antiproton decelerator holds the promise of delivering dense beams of 107 protons per minutes and low energy (100 MeV/c) with bunch lengths down to 200 nanoseconds.
The Antiproton Declerator project was approved on 7 February 1997.
The CERN research board officially approves the ALICE experiment. Re-using the L3 magnet experiment from the LEP, ALICE is designed to study quark-gluon plasma, a state of matter that would have existed in the first moments of the universe.
LHCb is the fourth experiment approved for the LHC. The experiment will study the phenomenon known as CP violation, which would help to explain why matter dominates antimatter in the universe.
The Large Electron-Positron collider was shut down for the last time at 8am on 2 November 2000. Members of government from around the world gathered at CERN on 9 October to celebrate the achievements of LEP and its 11 years of operational life. With the tunnel now available for work, teams began excavating the caverns to house the four big detectors on the Large Hadron Collider.
CERN celebrated its 50th anniversary in style, with the inauguration of the Globe of Science and Innovation (pictured, under construction) on 19 October. A gift from the Swiss Confederation, the Globe is an iconic wooden structure first used for the Swiss national exhibition in 2002 as a pavilion dedicated to the theme of sustainable development. It was designed by architects Thomas Büchi and Hervé Dessimoz of Geneva. The Globe is being developed into a new visitor and networking centre for the Laboratory — a focal point for CERN’s interaction with society.
The inauguration of the Globe in 2004 coincided with the official celebration of CERN’s anniversary, attended by representatives of the Organization’s 20 member states including the heads of state of France, Spain and Switzerland.
The ATLAS Barrel Toroid, then the largest superconducting magnet ever built, was switched on for the first time at CERN on 20 November 2006. The magnet is called the Barrel Toroid because of its barrel-like shape.
It provides a powerful magnetic field for ATLAS, one of the major particle detectors taking data at the Large Hadron Collider (LHC). The magnet consists of eight superconducting coils, each in the shape of a round-cornered rectangle, 5 metres wide, 25m long and weighing 100 tonnes, all aligned to millimetre precision.
The ATLAS Barrel Toroid was cooled down over a six-week period from July to August 2006 to reach –269°C . It was then powered up step-by-step to higher and higher currents, reaching 21 thousand amps for the first time during the night of 9 November. Afterwards, the current was switched off and the stored magnetic energy of 1.1 GigaJoules, the equivalent of about 10,000 cars travelling at 70 kilometres per hour, was safely dissipated, raising the cold mass of the magnet to –218°C.
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At 10.28am on 10 September 2008 a beam of protons was successfully steered around the 27-kilometre Large Hadron Collider (LHC) for the first time. The machine was ready to embark on a new era of discovery at the high-energy frontier.
LHC experiments address questions such as what gives matter its mass, what the invisible 96% of the universe is made of, why nature prefers matter to antimatter and how matter evolved from the first instants of the universe’s existence.
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The 53rd and final replacement magnet for the Large Hadron Collider (LHC) was lowered into the accelerator's tunnel today, marking the end of repair work above ground following the incident in September last year that brought LHC operations to a halt.
The final magnet, a quadrupole designed to focus the beam, was lowered in the afternoon and started its journey to Sector 3-4, the scene of the September incident. In total 53 magnets were removed from Sector 3-4. Sixteen that sustained minimal damage were refurbished and put back into the tunnel. The remaining 37 were replaced and will be refurbished to provide spares for the future.
The ALPHA experiment at CERN reported today that it succeeded in trapping antimatter atoms for over 16 minutes: long enough to begin to study their properties in detail. ALPHA is part of a broad programme at CERN’s antiproton decelerator investigating the mysteries of one of nature’s most elusive substances.
ALPAH studied 300 trapped antiatoms. Trapping antiatoms will allow antihydrogen to be mapped precisely using laser or microwave spectroscopy so that it can be compared to the hydrogen atom, which is among the best-known systems in physics. Any difference between matter and antimatter should become apparent under careful scrutiny.
In a seminar today the ATLAS and CMS experiments presented the status of their searches for the Standard Model Higgs boson. Their results were based on the analysis of considerably more data than those presented at the summer conferences, enough to make significant progress in the search for the Higgs boson, but not enough to make any conclusive statement on the existence or non-existence of the elusive Higgs. The main conclusion was that the Standard Model Higgs boson, if it exists, is most likely to have a mass constrained to the range 116-130 GeV by the ATLAS experiment, and 115-127 GeV by CMS. Tantalising hints were seen by both experiments in this mass region, but they were not yet strong enough to claim a discovery.
At a seminar held at CERN on 4 July 2012 as a curtain raiser to the year’s major particle physics conference, ICHEP2012 in Melbourne, the ATLAS and CMS experiments presented their latest preliminary results in the search for the long sought Higgs particle. Both experiments observe a new particle in the mass region around 125-126 GeV.