October 17, 2009

LHC: The Coldest Place In The Universe

The Large Hadron Collider (LHC) experiment is now more frigid than deep space, making it one of the coldest locations in the Universe, BBC News reported.

Recent adjustments in all eight sectors of the LHC have dropped the operating temperature to 1.9 kelvin (-271C; -456F).

Liquid helium maintains the intense cold in nearly 17-mile long magnets that bend particle beams around the LHC. 

The magnets are positioned end-to-end in a circular tunnel overlapping the Franco-Swiss border.

The cool-down marks a significant highlight just before the collider's forecasted re-start in late November.

A magnet complication termed a "quench" caused a ton of liquid helium to seep into the LHC tunnel, resulting in shut down of the LHC since September 19, 2008.

In order to repair the damage caused by the malfunction, the particle accelerator had to be heated up.

The Large Hadron Collider, operated by the European Organization for Nuclear Research (CERN) in Geneva, was created to reinvent the conditions following the Big Bang. 

The beams of protons will be shot down pipes passing through the magnets.  These beams will move in opposite directions around the central "ring" at nearly the speed of light. 

The proton beams intersect at various points around the tunnel, crashing into one another with cataclysmic energy. 

Scientists hope the experiment exposes elemental new insights into the nature of the cosmos by observing the debris of these collisions. 

The LHC operates at a temperature just a smidge above "absolute zero" (-273.15C) "“ the coldest temperature possible.  In remote parts of outer space the temperature is about 2.7 kelvin (-270C; -454F).

The LHC's superconducting magnets are designed to channel electric current with absolutely no resistance and very little power loss.  To develop this superconducting trait, magnets must be cooled to very low temperatures.  This is obtained by using liquid helium as a refrigerant within an intricate system of cryogenic lines. 

No particle physics facility on this scale has ever existed in such frigid conditions.  However, scientists are still testing the machine's new quench protection system and continue magnet powering tests before a beam can be circulated around the LHC ring. 

In just a week, a test injecting low-intensity particle beams into specific parts of the collider, not the entire "ring", could occur.

However, officials intend to circulate a beam around the LHC in the latter part of November.  At this time, scientists will shatter low-intensity beams together.

The beam's energy will be steadily increased so that the first high-energy collisions can take place.  This occurrence will mark the actual beginning of the LHC's investigative program. 

These high energy collisions are on target to occur in December, but could likely be postponed until January, James Gillies, CERN's Director of Communications said.

Mr. Gillies said careful operation of the accelerator will be crucial in this experiment.

"Whilst you're accelerating [the beams], you don't have to worry too much about how wide the beams are. But when you want to collide them, you want the protons as closely squeezed together as possible."

He also stated that "If you get it wrong you can lose beam particles - so it can take a while to perfect. Then you line up the beams to collide."

"In terms of the distances between the last control elements of the LHC and the collision point, it's a bit like firing knitting needles from across the Atlantic and getting them to collide half way."

The lab will shut down over the Christmas and New Year break.

The primary reason for this decision was based on workers' contracts.  Working through the holidays would warrant re-negotiated contracts.

Officials suggest that an upgraded early warning system or quench protection system should prevent cause for shut-down of the collider again.

CERN has invested almost $36 million in repairs following the malfunction, including upgrades to the quench protection system.


Image Caption: Two LHC magnets are seen before they are connected together. The blue cylinders contain the magnetic yoke and coil of the dipole magnets together with the liquid helium system required to cool the magnet so that it becomes superconducting. Eventually this connection will be welded together so that the beams are contained within the beam pipes. (CERN)


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