The LHC is installed in a tunnel 3.8 m. in diameter, buried 50 to 175 m. below ground. The tunnel straddles the French-Swiss border to the North-West of Geneva. [see map above]



Two counter rotating beams are injected into the LHC from the SPS accelerator (the Super Proton Synchrotron).



The proton beams are injected at 450 GeV and then accelerated to 7 TeV.



The beam moves around the LHC ring inside a continuous vacuum chambers which pass through a large number of magnets.



1232 dipole magnets bend the beam around the 27 km. ring. The momentum of the beam is very high and these magnets have to produce a very strong magnetic field.



To reach the high magnetic field required, high currents are needed. To avoid excessive resistive losses, the magnets are superconducting. A huge cryogenics system is required to produce the liquid helium needed to keep the magnets cold.



The cables of the magnets are of a very special design and conduct current without resistance in their superconducting state



The beams will be stored at high energy for 10 to 20 hours (with a bit of luck). In 10 hours the particles make four hundred million revolutions around the machine. During this time collisions take place inside the four main LHC EXPERIMENTS. More detailed accelerator physics challenges