Monday, July 26, 2010

LHC - Coldest Place In The Universe?

This news report covers the recent high energy physics meeting in France. One of the most important outcome of the meeting was the urge to build the ILC as the next generation particle collider to refine the results obtained at the LHC.

That is all fine and dandy. However, my eyes widened when I read this paragraph:

In March, the Large Hadron Collider produced a tiny bang, the most potent force on the tiny atomic level that humans have ever created.

Two beams of protons were sent hurtling in opposite directions toward each other in a 17-mile (27-kilometer) tunnel below the Swiss-French border — the coldest place in the universe at slightly above absolute zero.

Two problems with this last part:

1. LHC uses superconducting magnets to steer and control the proton beams. The beams do not collide under cryogenic temperatures. As far as I know, none of the detectors (ATLAS, CMS, etc.) are "superconducting".

2. While the magnets are cooled using liquid Helium, I can't imagine them being any lower than 1K. This is not "cold" at all, considering that we can get to milli Kelvin temperatures in many experiments already. So even on earth, the LHC is not the coldest place. I would guess that the rest of the Universe will have quite a say in that claim.

I suppose this is another example of a bit of bad reporting.



Gregor said...

1) In the segment you posted "superconducting" is not mentioned. What are you referring to?
Also: CMS uses superconducting Niobium-Titanium, ATLAS even uses two superconducting magnets.

2) The LHC ring (or at least the cooled part) is not the coldest place in the universe but most probably the largest place at a Temperature of or below 1.9 Kelvin.


ZapperZ said...

The magnets may be superconducting, and the temperature of the detectors may be cooled, but the collision point is not the "coldest place". It's a vacuum!

There are many of experiments on BEC-BCS crossover studies that have significantly lower temperatures than what one could get using LHe, even when one pumps on it. All the laser cooling experiments are way beyond what one could get at the LHC. So like I said, the LHC (or those magnets) is not even the coldest place on earth, much less, the universe.