The Large Hadron Collider (LHC) experiment has once again become one of the coldest places in the Universe.
All eight sectors of the LHC have now been cooled to their operating temperature of 1.9 kelvin (-271C; -456F) - colder than deep space.
The large magnets that bend particle beams around the LHC are kept at this frigid temperature using liquid helium.
The magnets are arranged end-to-end in a 27km-long circular tunnel straddling the Franco-Swiss border.
The cool-down is an important milestone ahead of the collider's scheduled re-start in the latter half of November.
The operating temperature of the LHC is just a shade above "absolute zero" (-273.15C) - the coldest temperature possible. By comparison, the temperature in remote regions of outer space is about 2.7 kelvin (-270C; -454F).
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 be cooled to very low temperatures.
The operating temperature of the LHC is just a shade above "absolute zero" (-273.15C) - the coldest temperature possible. By comparison, the temperature in remote regions of outer space is about 2.7 kelvin (-270C; -454F).
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 be cooled to very low temperatures.
For this reason, the LHC is innervated by a complex system of cryogenic lines using liquid helium as the refrigerant of choice.
No particle physics facility on this scale has ever operated in such frigid conditions.
But before a beam can be circulated around the 27km-long LHC ring, engineers will have to thoroughly test the machine's new quench protection system and continue with magnet powering tests.
Particle beams have already been brought "to the door" of the Large Hadron Collider. A low-intensity beam could be injected into the LHC in as little as a week.
This beam test would involve only parts of the collider, rather than the whole "ring".
http://news.bbc.co.uk/2/hi/science/nature/8309875.stm