About the Large Hadron Collider

Where is the LHC?

The LHC is installed in a tunnel 27 km in circumference, buried 50–150 metres below ground. Located between the Jura mountain range in France and Lake Geneva in Switzerland, the tunnel was built in the 1980s for the previous big accelerator, the Large Electron–Positron collider (LEP).

What will the LHC do?

The LHC will produce head-on collisions between two beams of particles of the same kind, either protons or lead ions. The beams will be created in CERN’s existing chain of accelerators and then injected into the LHC, where they will travel through a vacuum comparable to outer space. Superconducting magnets operating at extremely low temperatures will guide the beams around the ring.

Each beam will consist of nearly 3000 bunches of particles and each bunch will contain as many as 100 billion particles. The particles are so tiny that the chance of any two colliding is very small. When the bunches cross, there will be only about 20 collisions among 200 billion particles. However, bunches will cross about 30 million times per second, so the LHC will generate up to 600 million collisions per second.

At near lightspeed, a proton in the LHC will make 11,245 turns every second. A beam might circulate for 10 hours, travelling more than 10 billion kilometres—far enough to get to the planet Neptune and back again.

What is the LHC for?

Physicists are using the LHC to recreate the conditions just after the Big Bang, hoping to further our understanding of the Universe. The LHC will provide collisions at the highest energies ever observed in laboratory conditions, and four huge detectors—ALICE, ATLAS, CMS and LHCb—will observe these collisions, allowing physicists to explore new territory in matter, energy, space, and time. The scientific community expect the LHC to shed new light on many unanswered questions: What is the origin of mass? What is the nature of dark energy? Are there hidden dimensions of space?

 Who is involved in the LHC?

More than 10,000 scientists and engineers from around 500 academic institutes and industrial companies worldwide are contributing to the LHC project. Equipment is being built in many European countries, and in others such as Canada, India, Japan, Russia and the US.