Latest From the LHC

A talk at CERN today by Jorg Wenninger gives an update on the problems at Sector 34 and more information about what the prospects are for restarting the machine next year.

The cause of the accident has been identified as excessive resistance in a busbar interconnection between two magnets. Looking at logged data from before the accident, evidence for this excessive resistance was seen. Checking all the other sectors, a hint of a similar problem was found in one other cell, and that dipole will be replaced.

50 magnets are in the process of being removed from Sector 34, all to be out by Christmas. To avoid future similar accidents, the quench protection system is being upgraded, and the commissioning procedures will include a systematic search for excessive resistance problems. These measures can be implemented before next summer. There is also a plan is to add pressure release valves on every dipole cryostat, but this is highly problematic since it will require warming up all the sectors and likely would not allow the LHC to run with beam during 2009. The summary for 2009 plans reads:

Plan A:

  • Restart in (late) summer of 2009 with beam.
  • Beam intensity and energy limited to minimize any risk.
  • Plan B:

  • No beam before a complete ‘upgrade’ of the pressure relief system is implemented on all sectors.
  • Excludes beam in 2009.
  • Final decision in February?

    On a more cheerful note, tonight PBS will be broadcasting a documentary about the search for the Higgs at Fermilab called The Atom Smashers. It looks like this program should be about 10^(10^5) times better than a recent one featuring theorists. One of the filmmakers has a blog here. With the LHC out of commission for a while, the Higgs search at the Tevatron is where the action is, and the experimenters there may be the ones to find the Higgs or rule it out.

    Update: Two more recent presentations with information (including pictures!) about the LHC accident, repairs and plans for the future are here and here. For now, the plan is for the machine to be cold again next July.

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    18 Responses to Latest From the LHC

    1. Thomas R Love says:

      Peter, Thanks for mentioning “The Atom Smashers”. I checked the local listings and it is not playing, but it is available on DVD, so I shelled out $27.05 and hope to have it in a week.

    2. observer says:

      I tought that The Lorentz force and its consecuences (quenching, resistance and of course heating to name a few)were a solved problem, looks that it is not, well we have to wait how the upgrades go, is getting interesting now.

    3. Patrick says:

      The sentence “the experimenters [at the Tevatron] may be the ones to find the Higgs” could probably be rendered more acccurate by adding “or to confirm the LEP hints at a mass around 115-116 GeV/c2″. Actually, if the Higgs boson mass *is* at 115 GeV/c2 (as current insignificant Tevatron excesses seem to point to;-), it is only through a combination with LEP that the TeVatron might be able to confirm the observation (with a combined significance of 3 sigma). It actually turns out that many of the Tevatron current experimeters were LEP experimenters in 2000, so it’s probably what would happen in this happy situation!

    4. Roger says:

      If the Higgs were to be discovered by the Tevatron or Tevatron+LEP this would not be a happy situation, especially if no exotic physics was found at the LHC.

      We sold the idea of the LHC as a means of discovering the Higgs – for the sake of future funding it would be best if the LHC find it or disprove its existence.

      I realise, however, we live in the real world and I would be thrilled if the Tevatron picked the Higgs up first but this would cause problems later down the line when we ask for money for big projects.

    5. A. says:

      Sigh. I thought a bonus to landing another postdoc this year was that, as the LHC was coming online, I might still be in academia when the fallout of “we found/didn’t find the higgs/susy” etc etc started up.

      Also, the incoming director general of Cern, Rolf-Dieter Heuer, gave a talk on the LHC, this week, in Dublin. You can now stream it from

    6. Bont says:

      I couldn’t find what is quoted here from ‘talk at CERN today.’ Was it updated recently?

    7. Peter Woit says:


      The information quoted was from around page 45 on that document. Right now it appears to be having trouble loading, presumably because it has been slashdotted

    8. Bont says:

      Mr. Woit,

      When I loaded it yesterday, that page didn’t exist :-) Anyway, now it is available. Thank you very much.

    9. observer says:

      Off-topic but I am sure interesting. I just read in the news (canadian television) that Stephen Hawking is coming to the Perimeter Institute by January of 2009.

    10. Patrick says:

      To Roger:

      If the LHC were not to discover anything new, I agree entirely that we would not be in a happy situation ! It would probably mean the end of particle physics, irrespective of anything else.

      I disagree, however, on the fact that the LHC was sold to discover the Higgs. It was sold as an extraordinary step in energy towards discovery of TeV new physics. Let’s put it right: as repeatedly demonstrated in the past 15 years, an e+e- collider with energy of the order of mH + mZ + 30 GeV would be in much better a position to discover and finely study the Higgs boson than any hadron machine ever. In this perspective, the sooner the discovery is confirmed, the better !

      (Note: I am not a TeVatron experimenter, but an LHC experimenter, former LEP experimenter)

    11. Logan says:

      Hey I just found your blog and am pleasantly surprised. Thanks for letting me read your thoughts and ideas!
      Good to know that the cause of the accident was found and that steps to prevent it from occurring again are being taken. It would be unfortunate if we didn’t see another beam in 2009, but they gotta do what they gotta do.
      Hahaha 10^(10^5) better? – looks like I should find a video of that broadcast! Thanks for the heads up.

    12. Clayton says:

      Hello — I’m one of the co-directors of “The Atom Smashers.” Thanks for the link to my blog about the making of the film! I’m not sure about “10^(10^5) times better” than the other film you mentioned (that’s quite a tall order), but I hope our film was enjoyable to those of you who watched. If you missed it, or are interested in buying a copy (the dvd for sale is the 73-minute “director’s cut” with some extras, including the video Leon Lederman’s made to try to convince Ronald Reagan to support the Superconducting Super Collider), you can do that by visiting our site at Also the film will be shown again on PBS on January 27.

      We struggled with depicting many of the complexities of the fascinating search for the Higgs from the standpoint of Fermilab — it was a great story to tell with many interesting people and complex issues. We’re interested to hear your thoughts.

    13. mike says:

      Maybe CERN can be convinced to double their efforts in bringing the LHC online sooner. An argument can be made that if landscape theory is proven with the LHC, we can then transport ourselves to a parallel universe where our trillion $ debt suddenly becomes a trillion $ surplus which will then pay for the additional time spent on the LHC. I think this is referred to in political circles as a self-fulfilling investment plan (or alternatively a scientific bailout)!

    14. SpaceTime says:


      The Atom Smashers did broadcast on our local OTA (Over the Air) PBS station here WPBT in South Florida but it played on an OTA digital only channel (2.2) so if your using cable/dish you may not get it. PBS often repeat shows on other digital channels and they also run on a sister station channel 17 WLRN.

      This was an excellent show and pointed out the chronic anti-intellectual trend.

    15. Paul Collins says:

      It looks like access to the second presentation is restricted. The first one was very informative, however.

    16. woit says:

      Thanks Paul,

      Linking from here to a previously public CERN source of technical information about the state of the LHC seems to often lead them to shut off public access. This is too bad. In the past, their policy was mostly to be very open with technical information about exactly what was going on at the LHC. It appears that this has changed, in response to the huge amount of press attention they are getting, and because of the accident this past September.

    17. Pingback: The LHC turnon « Life as a Physicist

    18. Paul Collins says:

      Looks like the second one is available again.