Everything Science Forum

Geneva, 20 November 2006. The largest superconducting magnet ever built has successfully been powered up to its nominal operating conditions at the first attempt. Called the Barrel Toroid because of its shape, this magnet provides a powerful magnetic field for ATLAS, one of the major particle detectors being prepared to take data at CERN's Large Hadron Collider (LHC), the new particle accelerator scheduled to turn on in November 2007.

The ATLAS Barrel Toroid consists of eight superconducting coils, each in the shape of a round-cornered rectangle, 5m wide, 25m long and weighing 100 tonnes, all aligned to millimetre precision. It will work together with other magnets in ATLAS to bend the paths of charged particles produced in collisions at the LHC, enabling important properties to be measured. Unlike most particle detectors, the ATLAS detector does not need large quantities of metal to contain the field because the field is contained within a doughnut shape defined by the coils. This increases the precision of the measurements it can make.

At 46m long, 25m wide and 25m high, ATLAS is the largest volume detector ever constructed for particle physics. Among the questions ATLAS will focus on are why particles have mass, what the unknown 96% of the Universe is made of, and why Nature prefers matter to antimatter. Some 1800 scientists from 165 universities and laboratories representing 35 countries are building the ATLAS detector and preparing to take data next year.

The ATLAS Barrel Toroid was first cooled down over a six-week period in July-August to reach –269°C . It was then powered up step-by-step to higher and higher currents, reaching 21 thousand amps for the first time during the night of 9 November. This is 500 amps above the current needed to produce the nominal magnetic field. Afterwards, the current was switched off and the stored magnetic energy of 1.1 GigaJoules, the equivalent of about 10 000 cars travelling at 70km/h, has now been safely dissipated, raising the cold mass of the magnet to –218°C.

Correction: Ooops, even the great minds make mistakes. This story stated that each proton in the accelerator carries the energy of a bus. This is wrong. But added together all the protons in the machine will carry the equivalent energy of a 10-ton bus moving at 170 mph. Likewise the energy of the protons is not equivalent, as stated, to kilotons of TNT, but to some 360 pounds of TNT. Also, the machine is currently scheduled to begin operation in November.

Morning Edition, April 9, 2007 · This fall, physicists plan to throw the switch on what is arguably the largest and most complex science experiment ever conducted. An underground ring of superconducting magnets, reaching from Switzerland into France, will smash together subatomic particles at incredible force.

Physicists say they're not sure what will emerge from those collisions. They're hunting a mysterious, hypothetical particle called the Higgs boson. It is also possible they will make miniature black holes, or discover new dimensions of space-time.

Alvaro De Rujula is a staff scientist and theoretical physicist at CERN — which stands for Conseil Europeen pour la Recherche Nucleaire, or the European Council for Nuclear Research.

All Things Considered, April 9, 2007 · The cows grazing by the roads outside Geneva, Switzerland, have witnessed some pretty strange things these past few years: Trucks roll by carrying big, superconducting magnets that look like missiles, and other brightly colored pieces of scientific equipment. The pieces are all taken to warehouse-sized buildings, where they disappear down shafts that reach 300 feet into the earth.

The work is all part of an $8 billion project at the international physics laboratory called CERN. At its heart will be an enormously powerful particle accelerator capable of smashing subatomic particles together, reproducing the energies that existed a fraction of a second after the big bang. What comes out may solve some fundamental mysteries about how the universe is put together.

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