ATLAS is a particle physics experiment which has been designed to analyze data gathered from CERN's Large Hadron Collider (LHC) scheduled to start its activity in November 2007. One of the components of the ATLAS detector is its huge magnet system. According to CERN, the world's largest superconducting magnet has been switched on. Called the Barrel Toroid because of its shape, it consists of eight superconducting coils having a combined weight of 830 tons. But read more...
Why is this important? Because ATLAS is a particle physics experiment that will explore the fundamental nature of matter and the basic forces that shape our universe.
Before going further, below is a diagram showing the structure of the full ATLAS Detector (Credit: ATLAS Detector project). As you can see, it consists of four major components: the inner trackers which measure the momentum of each charged particle, the tile calorimeter which measures the energies carried by the particles, the muon spectrometer which identifies and measures muons, and the magnet system we are talking about today. Here is a link to other Detector images.
Now, let's look at this Barrel Toroidl magnets. The ATLAS Barrel Toroid systems consists of eight coils assembled radially and symmetrically around the beam axis. The coils are of a flat racetrack type with two double-pancake windings made of 20.5 kA aluminum stabilized NbTi superconductor. Each coil has an axial length of 25.3 m and extends radially from 9.4 m to 20.1 m. The total assembly weight will be 830 tons. The peak field provided by the Barrel Toroid coils is 3.9 T.
As you can see on the picture below, this system, a subset of the ATLAS detector, is itself pretty big (Credit: ATLAS Detector project). If you don't see the guy in the middle of the image, here is a link to more photos of the ATLAS Toroid Magnets.
The CERN press release adds more details about the goals of the Barrel Toroid system.
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.
And what will the ATLAS detector be used for? The 1,800 scientists from 35 countries which will work there hope to discover what happened in the moments after the Big Bang and "why Nature prefers matter to antimatter."
Sources: CERN Press Release, November 20, 2006; and various websites
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