A ceremony was held at CERN this week to mark the end of a crucial phase of installation of the Large Hadron Collider (LHC).

A large dipole magnet was symbolically lowered into the tunnel at 12:00 on Wednesday. This completes the basic installation of the more than 1700 magnets that make up the collider, which measures 27 km in circumference and is scheduled to be commissioned at the end of 2007.

Once in position, the magnets are connected to the cryogenic system to form a large string operating in superfluid helium, which will maintain the accelerator at a temperature just two degrees above absolute zero (-271°C). The cryogenic capabilities of the superconducting magnets were tested at CERN between 2004 and early this year, with the last dipole magnet passing its cryogenics testing on 1 March.

Air Liquide has supplied most of the distribution systems, in addition to the gases liquid helium, liquid argon, and nitrogen.