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Collider tour In the bowels of the monster

Thousands of curious members of the public recently ventured underground to see the world's largest particle accelerator, the Large Hadron Collider (LHC) at CERN. swissinfo.ch got a sneak peek inside the huge physics experiment.

The LHC is the world’s largest and most powerful particle accelerator. First started up on September 10, 2008, it consists of a 27-kilometre ring of superconducting magnets with a number of accelerating structures to boost the energy of the particles along the way.

Inside the accelerator, two high-energy particle beams travel at close to the speed of light before they are made to collide. The beams travel in opposite directions in separate beam pipes – two tubes kept in an ultrahigh vacuum. They are guided around the accelerator ring by a strong magnetic field maintained by superconducting electromagnets. The electromagnets are built from coils of special electric cable that operates in a superconducting state, efficiently conducting electricity without resistance or loss of energy. This requires chilling the magnets to minus 271.3°C – a temperature colder than outer space. For this reason, much of the accelerator is connected to a distribution system of liquid helium, which cools the magnets, as well as to other supply services.

The beams usually move through two vacuum pipes, but at four points, they collide in the hearts of the main experiments, known by their acronyms: ALICE, ATLAS, CMS, and LHCb.

The experiments investigate a wide range of physics, from the search for the famed Higgs boson particle to extra dimensions and particles that could make up dark matter.

(All photos: Thomas Kern, swissinfo.ch)