CERN Facts and Figures

The 27km tunnel which is 100m underground beneath Geneva was built to contain the LEP (Large electron positron collider) particle accelerator. This operated from 1989 to 2000. This was already the largest particle accelerator in the world. It had to be shut down in 2000 to make way for the LHC in the tunnel.

The LHC was first conceived in 1984, 23 years ago. After a number of feasibility studies, final approval for it to be built was given in 1994. Leader of the project, Welshman Dr. Lyn Evans, has been working on the project from its inception.

Large Hadron Collider - protons accelerated to nearly the speed of light both ways around the 27km track. They are then collided with each other creating the conditions that existed just after the big bang. Huge detectors will observe what happens.

The accelerator will use superconductivity for the electromagnets. This will allow electricity to flow through the electromagnets with virtually no resistance, hence needing much less energy to make the magnets much stronger. No resistance, no heat loss.

Temperature will be 1.7Kelvin or less than -271 ° C. This is even colder than outer space, making CERN the coolest place in the Universe!!

The first sector was cooled to this temperature in April this year. The sector was 3.3km long and initially it took 1200 tonnes of liquid nitrogen. This took it down to -193 ° C. When the sector reached this temperature it had become 10m shorter because of contraction.

Some of the questions that LHC experiments will try to answer:

•  What gives matter its mass?

•  What is the invisible 96% of the Universe is made of?

•  Why does nature prefers matter to antimatter?

•  How has matter evolved from the first instants of the Universe's existence?

The accelerator is now all in place and testing of the individual components is taking place. Each sector is gradually being cooled down to its working temperature.

An explosion occurred in the tunnel in March 2007 when one part (designed by Fermilab in America) failed. This has put the first actual experiments back by a few months. Originally planned for November 2007, they will now take place in May 2008.

ALICE and Atlas, the two huge detectors are inthe biggest man made caverns in the World, 35m wide by 55m long and 40m high

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