Large Hadron Collider? But I just met her!

To run the experiments on the LHC two separate but adjacent pipes run the 27km course, which combine at only four intersection points. Each pipe contains a proton beam, running in opposite directions to each other around the ring. It’s at the intersection points that the beams are guided to collide, and where the various detectors are placed to measure the results.

In order to contain and guide the beams tremendous magnetic forces are used – in all there are 1,232 superconducting dipole magnets, each 15 meters long, to bend the beams around the ring, while another 392 quadruple superconducting magnets, each 5-7 meters long, focus the beams. Many of these magnets weigh over 27 tonnes, and in order to operate at maximum efficiency are cooled using liquid helium to -271 degrees ceclius (absolute zero).

Before collisions take place the beams are accelerated to just shy of the speed of light (some 99.999 per cent the speed of light), at which time the proton beams lap the 27km circuit more than 11,000 times per second (!). In order to facilitate timed collisions, the beams aren’t continuous but instead are produced in ‘bunches’, which are estimated to contain some 280 trillion protons each, all running at near the speed of light, squeezed into a width thinner than a human hair. The energy contained within the beams is so potent that stray particles could destroy the superconducting magnets, and stopping the beams is a science unto itself.

When beams are crossed and collide at the intersection points, a number of detectors measure the results. The four key detectors include ATLAS (A Toroidal LHC ApparatuS) and CMS (Compact Muon Solenoid), which are designed to look for evidence of the Higgs-boson, dark matter, and even extra dimensions; ALICE (A Large Ion Collider Experiment) which will look for evidence of quark-gluon plasma, which is supposed to exist in the first moments of the Big Bang and could help reveal how matter was made; and the LHCb (Large Hadron Collider beauty – yes the acronyms don’t mean much!) which will analyse the interaction between matter and anti-matter in an attempt to determine what happened to the universe’s missing anti-matter.



Then there’s TOTEM (TOTal Elastic and diffractive cross section Measurement) and LHCf (Large Hadron Collider forward) – the results from which are designed to complement the other detectors, and shed light on the nature of cosmic rays (which, even before the first beams were sent around the LHC, could be seen being picked up by the detectors – rays passing through planet Earth, as it were). Of all the detectors the CMS is the biggest, weighing 12,500 tonnes.