Scientists successfully power up world's largest superconducting magnet

The world's largest superconducting magnet has been successfully powered up and is ready to help physicists answer fundamental questions about the nature of the universe and what happened immediately after the Big Bang. Called the Barrel Toroid because of its shape, the new m...

The world's largest superconducting magnet has been successfully powered up and is ready to help physicists answer fundamental questions about the nature of the universe and what happened immediately after the Big Bang.

Called the Barrel Toroid because of its shape, the new magnet will provide a powerful magnetic field for ATLAS, one of the particle detectors which will collect data at CERN's Large Hadron Collider (LHC).

The ATLAS Barrel Toroid consists of eight superconducting coils, each in the shape of a round-cornered rectangle 5m wide and 25m long, all aligned to millimetre precision. The Barrel Toroid will work with other magnets in ATLAS to bend the paths of charged particles produced in collisions at the LHC, enabling important properties to be measured.

'The toroidal magnets are critical to enabling us to measure the muons (a type of particle) produced in interactions,' said Dr Richard Nickerson, the UK's ATLAS project leader. 'These are vital to a lot of the physics we want to study, so the successful test of the magnets is a great step forward.'

Testing the magnet was a long process. During a period of six weeks in July and August, the Barrel Toroid was cooled down to a temperature of -269°C. It was then powered up step-by-step to higher and higher currents, until it reached 21,000 amps in the night of 9 November, 500 amps higher than the current needed to produce the magnetic field. The current was then switched off and the huge amounts of stored magnetic energy were safely dissipated.

'We can now say that the ATLAS Barrel Toroid is ready for physics,' commented Herman ten Kate, ATLAS Magnet System Project Leader.

The high energy collisions which will take place in ATLAS will help researchers from around the world answer fundamental questions, including what happened immediately after the Big Bang, why particles have mass, what the unknown 96% of the universe is made of, and why nature prefers matter to antimatter.

The construction of ATLAS is a true international collaborative effort, involving as it does some 1,800 scientists from 165 universities and laboratories in 35 countries. The LHC is due to become operational in November 2007.