Golden Jubilee Photos: Four giants break new ground

The four LHC experiments are on an unprecedented scale. The detectors will record particle collisions far more powerful than those at any other particle accelerator. One of the detectors, ATLAS, will be the largest-volume particle detector ever, a cylinder 45 metres long and 25 metres high. And the collaborations are a step beyond LHC's predecessor, LEP, involving even more people from more countries. Together, these four experiments promise to open a door to new realms of physics.

CMS and ATLAS are both general-purpose detectors, whose major quarry include the Higgs particle, which could give other particles their mass, and supersymmetric particles, which would bolster theories beyond the Standard Model. A major technical challenge for CMS has been acquiring 61 000 large, precision-grown crystals, denser than iron, for catching high-energy photons and electrons (1st bottom photo). ATLAS includes the world's largest superconducting magnets (2nd bottom photo), eight coils arranged into a large barrel shape that will physically support the rest of the detector while wrapping it in a massive magnetic field.

LHCb (1st top photo) aims to help explain why the Universe is all matter and practically no antimatter. This experiment is specially tuned to sort through billions of collisions that create pairs of beauty and antibeauty quarks, searching for matter-antimatter differences. ALICE (2nd top photo) will study collisions of lead nuclei that create a state of matter, the quark-gluon plasma, that probably existed in the first moments of the universe.