The LHC experiments
The main structure of the LHC is a 27 km (17 mile) circumference accelerator ring of superconducting magnets. Its primary job is to boost the energy of particles which will be smashed at the various detectors located around the ring.
Inside the tunnel are two separate vacuum tubes which channel particles at close to the speed of light. These "beam lines" travel in opposite directions. The particles are guided around ring by a strong magnetic field. Thousands of magnets of different size and type are used to direct the beams around the accelerator.
These include more than 1200 "dipole" magnets, each of which is 15m (49ft) in length and are used to bend the beams around the loop. Nearly 400 "quadrupole" magnets, each 5 to 7m (16-23ft) long are used to focus the beams. A third type of magnet is used to squeeze the beams closer together to increase the chances of a collision. Many of these magnets are built from coils of superconducting electric cable which conducts electricity with little resistance, and therefore little loss of energy.
To achieve this effect the cables are cooled close to absolute zero (-273C/ -459F) using liquid helium. This is fed into a sealed network in the accelerator at eight "cryoplants" located around the ring. All of this is monitored and managed from the control centre. Here, scientists will steer the particle beams to ensure that collisions occur at the detectors located around the circuit.
ALICE
While the other LHC detectors will use proton beams to do their science, Alice relies on smashing together electrically charged lead atoms. Scientists hope to re-create a state of matter called quark-gluon plasma which existed just after the Big Bang.
ATLAS
Atlas will search for new physics in the head-on collisions of protons that are accelerated to fantastic energies. Atlas will also look for Higgs boson, extra dimensions of space, microscopic black holes, and evidence for dark matter.
CMS
CMS - the Compact Muon Solenoid - and Atlas are the LHC's general purpose detectors that will go in search of the elusive Higgs boson, which gives other particles their mass. It will explore the fundamental nature of matter and the basic forces that shape our Universe.
LHCb
The LHC Beauty (LHCb) detector is designed to answer a specific question: where did all the anti-matter go? Equal amounts of matter and its opposite counterpart anti-matter were created in the Big Bang. But today we find no evidence of, e.g., anti-matter galaxies or stars.
LHCf
LHCf is located near the Atlas detector and will be used to simulate cosmic rays. When they collide with other molecules - mainly oxygen and nitrogen - in the upper atmosphere it can trigger a so-called "particle shower".
TOTEM
Totem is aligned with the CMS detector and will measure the size of protons and how they scatter, amongst other things. It will measure particles produced very close to the main beam lines using specially designed detectors housed in vacuum chambers known as "roman pots".
