ABSTRACT
The Large Hadron Collider (LHC), now operating for physics at CERN, the European Laboratory for Particle Physics in Geneva (Switzerland), is the largest scientific instrument in the world. It accelerates intense proton and ion beams up to energies of 7TeV (protons) or 2.759TeV/nucleon (Pb ions), and brings them into collision at the heart of four large detectors located around its 26.7 km circumference (Figure 1). The twin accelerators are composed of eight arcs, 2987m long, connected via 528-m-long straight sections. At the transition between arcs and straight sections, dispersion suppressors cancel horizontal dispersion arising in the arcs and help match the optics. In order to guide and focus its very rigid beams, the LHC makes use of several thousand high-field superconducting magnets, operating in superfluid helium below 2K. Although well above the preceding state-of-the-art in terms of beam energy and luminosity, the LHC is built on the knowledge and experience gained at previous high-energy accelerators: physics of hadron colliders was developed at the CERN ISR, the SPS antiproton collider and the TeVatron at Fermilab, while the TeVatron, HERA at DESY, RHIC at Brookhaven National Laboratory and CEBAF at Thomas Jefferson National Laboratory pioneered the technology of superconducting accelerators and the use of superfluid helium cooling.
