CERN particle accelerator attracts world's largest superconducting magnet

Adam Turner
Friday, 08 December 2006 04:34

Science - Space

The world’s largest superconducting magnet has gone into action as Europe's Large Hadron Collider (LHC) particle accelerator begins to take shape.

Built by the European Organization for Nuclear Research (CERN), the LHC is located inside a 27 kilometre circular underground tunnel, lying 100 metres below ground beneath Switzerland and France. Scientists will use the LHC to recreate the conditions just after the Big Bang, by colliding two beams of protons travelling in opposite directions at close to the speed of light.

Thousands of magnets are required to navigate the beams of particles around the accelerator. These include the superconducting main magnets, with 15 metre dipole magnets used to guide the beams 5 to 7 metre quadrupole magnets used to focus the beams. To achieve this, the magnets must perform at the most efficient superconducting state, without loss of energy, which requires chilling them to -271° Celsius - colder than outer space.

The latest magnet completes the full set of 1624 main magnets required to bend the path of the particle beams around the accelerator. It lies at the heart of the ATLAS Barrel Toroid, a particle detector designed specifically for the LHC and the largest volume particle detector ever constructed for particle physics. The ATLAS Barrel Toroid consists of eight superconducting coils, each in the shape of a round-cornered rectangle, 5 metres wide, 25 metres long and weighing 100 tonnes, all aligned to millimetre precision.

The ATLAS Barrel Toroid has been successfully tested after a six week cooling process to reach –269° Celsius. Among the questions it will focus on are why particles have mass, what the unknown 96 per cent of the Universe is made of, and why nature prefers matter to antimatter.