The history of CERN
  1. 09/12/1949

    Origins

    At the end of the Second World War, European…

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  2. 05/05/1952

    Early beginnings

    The first meeting of the CERN Council quickly…

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  3. 01/10/1952

    Where to build?

    Geneva was selected as the site for the CERN…

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  4. 29/06/1953

    The convention is complete

    The draft convention was completed in the alotted…

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  5. 17/03/1954

    Breaking ground

    On 17 May 1954, the first shovel of earth was dug…

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  6. 29/09/1954

    The European Organization for Nuclear Research is born

    At the sixth session of the CERN Council, which…

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  7. 11/05/1957

    CERN's first accelerator - the Synchrocyclotron - starts up

    The 600 MeV Synchrocyclotron (SC), built in 1957…

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  8. 24/11/1959

    The Proton Synchrotron starts up

    The Proton Synchrotron (PS) accelerated protons…

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  9. 01/09/1965

    First observations of antinuclei

    By 1965, all three particles that make up atoms (…

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  10. 17/01/1968

    Georges Charpak revolutionizes detection

    In the 1960s, detection in particle physics…

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  11. 27/01/1971

    First proton collisions: The Intersecting Storage Rings

    By the late 1950s, physicists knew that a huge…

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  12. 10/02/1971

    Council commissions the Super Proton Synchrotron

    Seven kilometres in circumference, the Super…

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  13. 31/07/1974

    Super Proton Synchrotron tunnel completed

    A few months after the signature of the agreement…

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  14. 03/05/1976

    The Super Proton Synchrotron starts up

    The Super Proton Synchrotron (SPS) became the…

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  15. 04/04/1981

    First proton-antiproton collisions

    The Intersecting Storage Rings produced the world…

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  16. 20/01/1983

    W and Z particles discovered

    In 1979, CERN decided to convert the Super Proton…

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  17. 11/06/1986

    Heavy-ion collisions begin

    Just after the big bang the universe was too hot…

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  18. 08/02/1988

    LEP tunnel completed

    The excavation of the tunnel for the Large…

    Know more
  19. 14/07/1989

    Large Electron-Positron collider: First injection

    With its 27-kilometre circumference, the Large…

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  20. 20/12/1990

    The world's first website and server go live at CERN

    By Christmas 1990, Berners-Lee had defined the…

    Know more
  21. 15/09/1995

    First antiatoms produced: antihydrogen, at CERN

    A team led by Walter Oelert created atoms of…

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  22. 31/01/1997

    CMS and ATLAS experiments approved

    Four years after the first technical proposals,…

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  23. 07/02/1997

    Antiproton Decelerator approved

    In 1996 CERN's antiproton machines – the…

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  24. 14/02/1997

    ALICE experiment approved

    The CERN research board officially approves the…

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  25. 17/09/1998

    LHCb experiment approved

    LHCb is the fourth experiment approved for the…

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  26. 02/11/2000

    LEP's final shutdown

    The Large Electron-Positron collider was shut…

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  27. 19/10/2004

    CERN celebrates its 50th birthday

    CERN celebrated its 50th anniversary in style,…

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  28. 20/11/2006

    World's largest superconducting magnet switches on

    The ATLAS Barrel Toroid, then the largest…

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  29. 10/09/2008

    The LHC starts up

    At 10.28am on 10 September 2008 a beam of protons…

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  30. 19/09/2008

    Incident at the LHC

    On 19 September 2008, during powering tests of…

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  31. 30/04/2009

    Final magnet goes underground after LHC repair

    The 53rd and final replacement magnet for the…

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  32. 05/06/2011

    ALPHA traps antimatter atoms for 1000 seconds

    The ALPHA experiment at CERN reported today that…

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  33. 13/12/2011

    Tantalising hints of the Higgs

    In a seminar today the ATLAS and CMS experiments…

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  34. 04/07/2012

    ATLAS and CMS observe a particle consistent with the Higgs boson

    On 4 July 2012, as a curtain raiser to the year…

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  35. 14/07/2015

    Discovery of pentaquarks

    Possible layout of the quarks in a pentaquark…

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  36. 28/09/2018

    Esplanade des Particules: CERN’s new official address

    CERN, the État de Genève and the Ville de Meyrin…

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Origins

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.

Early beginnings

The first meeting of the CERN Council quickly followed the signing of the agreement. It took place at UNESCO from 5-8 May 1952 with Switzerland’s Paul Scherrer in the chair. At this meeting, governments wishing to host the new laboratory were invited to submit proposals before the end of July and the first five officials were appointed. Edoardo Amaldi was made Secretary General of the provisional organisation, Cornelis Bakker from Amsterdam headed the group that would draw up plans for the laboratory’s first machine -- a synchrocyclotron with an energy of at least 500 MeV, Niels Bohr headed the theory group, and Odd Dahl from Norway got the job of exploring options for the originally conceived 'bigger and more powerful' machine that would bring together European science and scientists.Lew Kowarski -- who originally proposed setting up a laboratory for fundamental research, unlinked to military goal, with a nuclear accelerator -- was tasked with organising and setting up an international laboratory, from financial procedures to buildings and workshops.

Where to build?

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. It was selected from proposals submitted by the Danish, Dutch, French and Swiss governments. But Geneva's central location in Europe, Swiss neutrality during the war and that fact that it already hosted a number of international organisations all playing a role gave it the edge. While preparations were being made to establish the laboratory in Geneva, theoretical work would be carried out in Copenhagen.

The convention is complete

The draft convention was completed in the alotted 18 months and approved unanimously by the representatives of the eleven countries that had signed the original agreement plus the UK, and the document was made available for signature.  The CERN Convention established financial contributions, which are calculated on the basis of net national income over recent years so that each Member State pays according to their means. 

Breaking ground

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.

The European Organization for Nuclear Research is born

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.

CERN's first accelerator - the Synchrocyclotron - starts up

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 starts up

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.

First observations of antinuclei

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.

Georges Charpak revolutionizes detection

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.

First proton collisions: The Intersecting Storage Rings

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.

Council commissions the Super Proton Synchrotron

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.

Super Proton Synchrotron tunnel completed

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 starts up

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.

First proton-antiproton collisions

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.

W and Z particles discovered

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. Find out more

Heavy-ion collisions begin

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.

LEP tunnel completed

The excavation of the tunnel for the Large Electron-Positron Collider – Europe’s largest civil-engineering project prior to the Channel Tunnel – is completed on 8 February 1988. The two ends of the 27-kilometre ring come 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. 

Large Electron-Positron collider: First injection

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.

The world's first website and server go live at CERN

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!!"

First antiatoms produced: antihydrogen, at CERN

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.

CMS and ATLAS experiments approved

Four years after the first technical proposals, the experiments CMS and ATLAS are officially approved. Both are general-purpose experiments designed to explore the fundamental nature of matter and the basic forces that shape our universe, including the Higgs boson.

Antiproton Decelerator approved

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 Antiproton Declerator project was approved on 7 February 1997.

ALICE experiment approved

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 experiment approved

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.

LEP's final shutdown

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 celebrates its 50th birthday

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. Check out the website that contains a record of the activities that marked the Organization’s 50th Anniversary.

World's largest superconducting magnet switches on

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. Read the press release

The LHC starts up

At 10.28am on 10 September 2008 a beam of protons is successfully steered around the 27-kilometre Large Hadron Collider (LHC) for the first time. The machine is 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. Explore the resources prepared for press.

Incident at the LHC

On 19 September 2008, during powering tests of the main dipole circuit in Sector 3-4 of the LHC, a fault occurs in the electrical bus connection in the region between a dipole and a quadrupole, resulting in mechanical damage and release of helium from the magnet cold mass into the tunnel. Proper safety procedures are in force, the safety systems perform as expected, and no-one is put at risk. More about the incident:  A full technical analysis of the incident is available here.  Or read an analysis of the LHC incident on CERN's press office website. 

Final magnet goes underground after LHC repair

The 53rd and final replacement magnet for the Large Hadron Collider (LHC) is lowered into the accelerator tunnel, marking the end of repair work above ground following the incident in September the year before that brought LHC operations to a halt. The final magnet, a quadrupole designed to focus the beam, is lowered in the afternoon and starts its journey to Sector 3-4, the scene of the September incident. In total 53 magnets were removed from Sector 3-4 after the incident. 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.

ALPHA traps antimatter atoms for 1000 seconds

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.

Tantalising hints of the Higgs

In a seminar today the ATLAS and CMS experiments present the status of their searches for the Standard Model Higgs boson. Their results are 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 is 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.

ATLAS and CMS observe a particle consistent with the Higgs boson

ATLAS spokesperson, Fabiola Gianotti, presents the collaboration's results. (IMAGE: CERN)

On 4 July 2012, as a curtain raiser to the year’s major particle physics conference, ICHEP 2012 in Melbourne, the ATLAS and CMS experiments present their latest preliminary results in the search for the long-sought Higgs particle. Both experiments have observed a new particle in the mass region around 125-126 GeV.  The next step is to determine the precise nature of the particle and its significance for our understanding of the universe. Are its properties as expected for the long-sought Higgs boson, the final missing ingredient in the Standard Model of particle physics? Or is it something more exotic? The Standard Model describes the fundamental particles from which we, and every visible thing in the universe, are made, and the forces acting between them. All the matter that we can see, however, appears to be no more than about 4% of the total. A more exotic version of the Higgs particle could be a bridge to understanding the 96% of the universe that remains obscure. Explore the resources prepared for press.

Discovery of pentaquarks

Possible layout of the quarks in a pentaquark particle. The five quarks might be tightly bound (left). They might also be assembled into a meson (one quark and one antiquark) and a baryon (three quarks), weakly bound together (Image: Daniel Dominguez) From the CERN website: The LHCb experiment at CERN’s Large Hadron Collider has reported the discovery of a class of particles known as pentaquarks. The collaboration has submitted today a paper reporting these findings to the journal Physical Review Letters. “The pentaquark is not just any new particle,” said LHCb spokesperson Guy Wilkinson. “It represents a way to aggregate quarks, namely the fundamental constituents of ordinary protons and neutrons, in a pattern that has never been observed before in over 50 years of experimental searches. Studying its properties may allow us to understand better how ordinary matter, the protons and neutrons from which we’re all made, is constituted.” Our understanding of the structure of matter was revolutionized in 1964 when American physicist Murray Gell-Mann  proposed that a category of particles known as baryons, which includes protons and neutrons, are comprised of three fractionally charged objects called quarks, and that another category, mesons, are formed of quark-antiquark pairs. Antiquarks are quarks of antimatter. Gell-Mann was awarded the Nobel Prize in physics for this work in 1969. This quark model also allows the existence of other quark composite states, such as pentaquarks composed of four quarks and an antiquark. Earlier experiments that have searched for pentaquarks have proved inconclusive. Where the LHCb experiment differs is that it has been able to look for pentaquarks from many perspectives, with all pointing to the same conclusion. It’s as if the previous searches were looking for silhouettes in the dark, whereas LHCb conducted the search with the lights on, and from all angles. The next step in the analysis will be to study how the quarks are bound together within the pentaquarks. Read the full Press Release. Read the LHCb article.

Esplanade des Particules: CERN’s new official address

Pierre-Alain Tschudi, the Mayor of Meyrin, Mauro Poggia, state councillor of Geneva and Fabiola Gianotti, CERN Director-General (©CERN)

CERN, the État de Genève and the Ville de Meyrin inaugurate the brand-new Esplanade des Particules, an open space firmly focused on welcoming visitors and the general public. This large public space, designed with pedestrians and sustainable transport in mind, enhances the integration of CERN into the local urban landscape and improves access to the Laboratory.  From today onwards, CERN’s official address will be 1 Esplanade des Particules.