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LHC Shut Down By Transformer Malfunction
Ortega-Starfire writes "A 30-ton transformer in the Large Hadron Collider malfunctioned, requiring complete replacement on the day the LHC came online. No one at CERN reported any problems, and they only released this data once the Associated Press sent people to investigate rumors of problems. I guess it's hard to just sweep a 30-ton transformer breaking under the rug."
a) Yes, it is a big complicated machine, things will break, this device barely impacted the overall schedule at all. People have been working on this project for about 2 decades. A week or two isn't in the least bit significant.
b) If this had happened say, 5 years from now, this point would be as irrelevant as it is now. And as noteworthy.
c) Cosmic rays interact in our atmosphere in the PeV range (Peta Electron Volt), the LHC smashes particles together in the 14 TeV (Tera Electron Volt). Sooo.... it operates at energy levels an order of magnitude less than what currently happens on Earth... I don't know about you, but I feel pretty safe about the whole thing.
d) They did fix it pronto, and it does work. Little things break, I know where I work (a not so little accelerator) I didn't hear a PEEP about this incident and we have been directly and closely involved in the LHC.
In short, I agree with hairykrishna, this isn't really news. Just another instance of the media trying to make a big deal out of something small.
Can one of you physicists tell me how 4.5 Kelvin is different from 2 Kelvin, operationally?
The magnets they use to shape and steer the beam require about 12,000 amps, so they use superconductors. Between 2K and 4.5K, the superconductor undergoes a phase change and becomes non-superconducting, and the resistance goes from zero to not zero all of a sudden. The 12,000 amps suddenly produces an incredible amount of heat (P=I^2R) which drastically increases the pressure from the liquid He. That much pressure means the He needs to escape (violently), causing all sorts of trouble. It's called a 'quench.'
The maximum magnetic field you can put on a superconductor depends on temperature. You can operate a superconducting magnet with a stronger magnetic field at 2 Kelven instead of 4.5 kelvin. Also, below 2.17 degrees kelvin, helium becomes super-fluid and has better heat conductivity - this is important in some applications. For alternating fields (like microwaves) superconductors are not perfectly superconducting, they have a bit if residual resistance. This resistance decreases as the temperature goes down.
They have day-to-day log of the activities at https://lhc-commissioning.web.cern.ch/lhc-commissioning/dailynews/index.htm I didn't have any problems finding this logs at the LHC website.
Transformer outage and cryogenics breakdown is logged on September 13. They were not 'rumors'.
I refuse to use
The webcam is a great source of information on CMS :), but if you want to know the status of the LHC, check the following links:
The current status of the beam can always be viewed here
All other status informations are linked from here
So maybe they didn't make a press release, but perhaps journalists should be smart enough to find these pages instead of claiming conspiracies?