Colder than outer space here on earth.
Science at it's best.
CERN's LHC reaches temperature colder than deep outer spaceBy ANI Wednesday April 11, 03:12 PM
Geneva, Apr 11 (ANI): For the first time, temperatures in the Large Hadron Collider (LHC) in CERN's laboratory in Geneva has reached 1.9 Kelvin, colder than deep outer space.
Researchers say the temperature reached just one eight of the 27-kilometre LHC ring, and the entire ring needs to be cooled down to this temperature so that the super conducting magnets that guide and focus the proton beams, remain in a superconductive state.
Such a state allows the current to flow without resistance, creating a dense, powerful magnetic field in relatively small magnets.
Guiding the two proton beams as they travel nearly the speed of light, curving around the accelerator ring and focusing them at the collision points is not easy as a total of 1650 main magnets need to be operated in a superconductive state.
"This is the first major step in the technical validation of a full-scale portion of the LHC," said LHC project leader Lyndon Evans.
According to him, there are three parts to the cool down process, with many tests and intense checking in between.
During the first phase, the sector is cooled down to 80 K, slightly above the temperature of liquid nitrogen. At this temperature the material will have seen 90 percent of the final thermal contraction, a three millimetre per metre shrinkage of steel structures. Each of the eight sectors is about 3.3 kilometres long, which means shrinkage of 9.9 metres!
To deal with this amount of shrinkage, specific places have been designed to compensate for it, including expansion bellows for piping elements and cabling with some slack. Tests are done to make sure no hardware breaks as the machinery is cooled.
The second phase brings the sector to 4.5 K using enormous refrigerators. Each sector has its own refrigerator and each of the main magnets is filled with liquid helium, the coolant of choice for the LHC because it is the only element to be in a liquid state at such a low temperature.
The final phase requires a sophisticated pumping system to help bring the pressure down on the boiling Helium and cool the magnets to 1.9 K. To achieve a pressure of 15 millibars, the system uses both hydrodynamic centrifugal compressors operating at low temperature and positive-displacement compressors operating at room temperature.
Cooling down to 1.9 K provides greater efficiency for the superconducting material and helium's cooling capacity. At this low temperature helium becomes superfluid, flowing with virtually no viscosity and allowing greater heat transfer capacity.
"It's exciting because for more than ten years people have been designing, building and testing separately each part of this sector and now we have a chance to test it all together for the first time," said Serge Claudet, head of the Cryogenic Operation Team.
According to Claudet, the conditions are now established to allow testing of all magnets in this sector to their ultimate performance. (ANI)