The Large Hadron Collider (LHC)  is being built in a circular tunnel 27 km in circumference. The tunnel is buried around 50 to 175 m. underground. It straddles the Swiss and French borders on the outskirts of Geneva.

The first beams were circulated successfully on 10th September 2008. Unfortunately on 19th September a serious fault developed damaging a number of superconducting magnets. The repair will required a long technical intervention which overlaps with the planned winter shutdown. The LHC beam will, therefore, not see beam again before September 2009.

The LHC is designed to collide two counter rotating beams of protons or heavy ions. Proton-proton collisions are foreseen at an energy of 7 TeV per beam.

• The beams move around the LHC ring inside a continuous vacuum guided by magnets.

• The magnets are superconducting and are cooled by a huge cryogenics system. The cables conduct current without resistance in their superconducting state.

• The beams will be stored at high energy for hours. During this time collisions take place inside the four main LHC experiments.