Journey 100 metres towards the centre of the Earth

It’s an amazing engineering challenge - the lowering of the first tremendous endcap disc of the CMS experiment slowly and carefully 100 m underground into the experimental cavern. The disc is one of 15 large pieces to make the grand descent. It’s a uniquely shaped slice, 16 m high, about 50 cm thick and weighing 400 tonnes. The solid steel structure of the disc forms part of the magnet return yoke and is equipped on both sides with muon chambers. A special gantry crane will lower the element, with just 20 cm of leeway between the edges of the detector and the walls of the shaft.

CMS is one of the four main experiments that will take data at the world's highest energy particle accelerator, the Large Hadron Collider (LHC) at CERN. The LHC is a 27-km circular ring 100 m underground. The CMS detector weighs a total of 12 500 tonnes and is constructed on the surface. Once all of the pieces are fully equipped, lowered underground and re-tested, they will be pushed together in preparation for the LHC start-up in spring 2008.

For more information about the CMS experiment, visit the CMS website.

December 2006