Big magnet ready to face the big questions of the universe

Nov 20, 2006
Big magnet ready to face the big questions of the universe
Barrel Toroid Magnet.

The largest superconducting magnet ever built has successfully been powered up to its operating conditions at the first attempt. Called the Barrel Toroid because of its shape, this magnet is a vital part of 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.

ATLAS will help scientists probe the big questions of the Universe – what happened in the moments after the Big Bang? Why does the material in the Universe behave the way it does? Why is the Universe we can see made of matter rather than anti-matter?

UK scientists are a key part of the ATLAS collaboration and Dr Richard Nickerson, UK ATLAS project leader, who is from the University of Oxford welcomed this important milestone "The toroidal magnets are critical to enabling us to measure the muons (a type of particle) produced in interactions. 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."

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 allows the ATLAS detector to be very large, which in turn 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 (including 12 from the UK) 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 –269oC. 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 GJ, the equivalent of about 10 000 cars travelling at 70km/h, has now been safely dissipated, raising the cold mass of the magnet to –218oC.

"We can now say that the ATLAS Barrel Toroid is ready for physics," said Herman ten Kate, ATLAS magnet system project leader.

The ATLAS Barrel Toroid is financed by the ATLAS Collaboration and has been built through close collaboration between the French CEA-DAPNIA laboratory (originator of the magnet's design), Italy's INFN-LASA laboratory and CERN. Components have been contributed in-kind by national funding agencies from industries in France (CEA), Italy, Germany (BMBF), Spain, Sweden, Switzerland, Russia, and the Joint Institute for Nuclear Research (JINR), an international organization based near Moscow. The final integration and test of the coils at CERN, as well as assembly of the toroid in the ATLAS underground cavern, was done with JINR providing most of the manpower and heavy tooling.

Source: Particle Physics & Astronomy Research Council

Explore further: Watching the structure of glass under pressure

add to favorites email to friend print save as pdf

Related Stories

A hint of Higgs: An update from the LHC

Aug 16, 2011

The physics world was abuzz with some tantalizing news a couple of weeks ago. At a meeting of the European Physical Society in Grenoble, France, physicists -- including some from Caltech -- announced that ...

The Year of the Higgs?

Feb 21, 2011

This February, researchers will renew their search for one of the universe's most elusive mysteries, the Higgs boson--a hypothetical particle that if found would give an insight into why particles have certain mass.

Hunt for dark matter closes in at Large Hadron Collider

Jan 26, 2011

(PhysOrg.com) -- Physicists are closer than ever to finding the source of the Universe's mysterious dark matter, following a better than expected year of research at the Compact Muon Solenoid (CMS) particle ...

The ATLAS Pixel Detector

Sep 03, 2008

With the Large Hadron Collider start-up only weeks away, SLAC researchers working on the LHC are feeling the excitement. SLAC has been involved in designing and building the ATLAS (A Toroidal LHC ApparatuS) ...

Physics failure could mean success

Jan 25, 2005

It might sound like a bit of a surprise, but a handful of scientists participating in the $4-billion international experiment to discover the Higgs boson, the Holy Grail of particle physics, hope the effort fails. The Large Had ...

Recommended for you

Watching the structure of glass under pressure

16 hours ago

Glass has many applications that call for different properties, such as resistance to thermal shock or to chemically harsh environments. Glassmakers commonly use additives such as boron oxide to tweak these ...

Inter-dependent networks stress test

19 hours ago

Energy production systems are good examples of complex systems. Their infrastructure equipment requires ancillary sub-systems structured like a network—including water for cooling, transport to supply fuel, and ICT systems ...

Explainer: How does our sun shine?

20 hours ago

What makes our sun shine has been a mystery for most of human history. Given our sun is a star and stars are suns, explaining the source of the sun's energy would help us understand why stars shine. ...

User comments : 0