Readying for its restart in mid November, the Large Hadron Collider (LHC) has again reached the landmark cool-down stage of experiment and become one of the coldest places in the Universe.

It was reported last week that all eight sectors of the LHC have now been cooled to their operating temperature of 1.9 kelvin (-271°C) - colder than deep space itself.

The large superconducting magnets that bend particle beams around the LHC are kept super-cool using large volumes of liquid helium. A fault with two of the LHC’s magnets in September 2008 caused a large helium leak (thought to be a tonne of liquid helium) and the project was temporarily shut-down for repair and restart in 2009.

That restart is now set for mid November and the cool-down is seen as an important milestone ahead of this occasion. The LHC’s magnets are designed to be superconducting, which means they channel electric current with zero resistance and very little power loss. But to become superconducting, the magnets must first be cooled to extremely low temperatures using a complex series of cryogenic lines and liquid helium as the refrigerant.

Technology and/or gases and services have been provided by industrial gas companies including The Linde Group, Messer and Air Liquide, at different stages of involvement in the historic LHC physics project.

The most powerful physics experiment ever built, the LHC is seeking to recreate the conditions just after the ‘Big Bang’. It is operated by the European Organization for Nuclear Research (CERN), based in Geneva.