Giant magnet goes underground at CERN

The central section of the CMS detector starts its 10-hour descent underground (Image: CERN)

Geneva, 28 February 2007. At 6:00 am this morning the heaviest piece of the Compact Muon Solenoid (CMS) particle detector began a momentous journey into the experiment's cavern, 100 metres underground at CERN1. Using a huge gantry crane, custom-built by the Vorspann System Losinger Group, the pre-assembled central piece, containing the magnet and weighing as much as five Jumbo jets (1920 tonnes) is being gently lowered into place. “This is a challenging feat of engineering, as there are just 20 cm of leeway between the detector and the walls of the shaft,” said Austin Ball, Technical Coordinator of CMS.  “The detector is suspended by four massive cables, each with 55 strands and attached to a step-by-step hydraulic jacking system, with sophisticated monitoring and control to ensure the object does not sway or tilt.” The entire process is expected to take about ten hours to complete.

The first seven of 15 pieces of the CMS detector have already been lowered, with the first piece arriving in the cavern on 30 November 2006. The giant element being lowered today, which is 16 m tall, 17 m wide and 13 m long, marks the halfway point in the lowering process with the last piece scheduled to make its descent in summer 2007.

This is a unique experience for a high-energy physics collaboration, as experiments are typically constructed underground where the particle accelerator is located. CMS has broken with tradition in order to start assembly before completion of the underground cavern, taking advantage of a spacious surface assembly hall to pre-assemble and pre-test the solenoid magnet and the various detectors used to measure particles resulting from collisions.

CMS is a general purpose experiment being prepared to take data at CERN’s Large Hadron Collider2 (LHC). Experiments at the LHC will allow physicists to complete a journey that started with Newton's description of gravity. Gravity acts on mass, but so far science is unable to explain why certain particles have the masses they have. Experiments such as CMS may provide the answer. LHC experiments will also probe the mysterious missing mass and dark energy of the universe – visible matter seems to account for just 4% of what must exist. They will investigate the reason for nature's preference for matter over antimatter, and will probe matter as it existed at the very beginning of time. “This is a very exciting time for physics,” said CMS spokesman Tejinder Virdee, “the LHC is poised to take us to a new level of understanding of our Universe.”

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Footnote(s)

1. CERN, the European Organization for Nuclear Research, is the world's leading laboratory for particle physics. It has its headquarters in Geneva. At present, its Member States are Austria, Belgium, Bulgaria, the Czech Republic, Denmark, Finland, France, Germany, Greece, Hungary, Italy, Netherlands, Norway, Poland, Portugal, Slovakia, Spain, Sweden, Switzerland and the United Kingdom. India, Israel, Japan, the Russian Federation, the United States of America, Turkey, the European Commission and UNESCO have Observer status.

2. The LHC is a particle accelerator, which will be the world’s largest and most complex scientific instrument when it switches on in November 2007.

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