LHC tunnel. The LHC (large hadron collider) in its 27-kilometre tunnel at CERN (the European particle physics laboratory) near Geneva, Switzerland. The LHC is an underground ring of superconducting magnets housed in this pipe-like structure (running from upper left to lower right), or cryostat. The cryostat is cooled by liquid helium to keep the operating temperature at just above absolute zero. The LHC works by accelerating two counter-rotating beams of protons to an energy of 7 tera electron volts (TeV). It then forces these beams to collide head-on near two main detectors, known as the CMS (Compact Muon Solenoid) and ATLAS (A Toroidal LHC Apparatus), which detect the sub-atomic particles resulting from the collision. The LHC is scheduled to start operating in May 2008.