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.

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.

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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.

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.

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.

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 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.

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.