CMS - the Compact Muon Solenoid - and Atlas are the LHC's general purpose detectors that will go in search of the elusive Higgs boson, which gives other particles their mass.
It will explore the fundamental nature of matter and the basic forces that shape our Universe.
Although it has the same scientific goals as the Atlas detector, CMS will use different technical solutions and a different design of its magnet system to carry out its science.
The CMS detector is built around a huge solenoid magnet. This is a cylindrical coil of superconducting cable which generates a strong magnetic field.
This field is about 100,000 times as strong as the Earth's.
This magnetic field is hemmed in by a steel "yoke" which, at 12,500 tonnes, forms the bulk of the weight of CMS.
Unlike the LHC's other detectors, which were built in situ underground, CMS was constructed on the surface, before being lowered underground in 15 sections and reassembled.
Located at Cessy in France, more than 2,000 scientists from about 40 countries are involved in the project.
One-Minute World News
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