LHC at the High Energy Frontier

A few minutes ago, one of the beams of the LHC was ramped up to an energy of 1180 GeV, besting the Tevatron’s top beam energy of 980 GeV.

Update: Actually the beam was lost at 1040 GeV, which is still a record high energy.

Update: A few minutes ago both beams were successfully ramped up simultaneously to 1180 GeV.

Update: Wow, that was quick. First publication based on LHC data is now out, from ALICE, based on data gathered a week ago. Nothing at all unexpected, this is just based on 284 total events, at the already well-studied energy of 900 GeV.

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18 Responses to LHC at the High Energy Frontier

  1. Ralph says:

    They just got beam 1 to 1180GeV with 2e9 protons. They started with both beams but lost about 90% of beam 2 around 700GeV.

  2. D R Lunsford says:

    What exactly happens when they “lose the beam”? (I’ve been studying physics for decades and still have almost no clue about what happens at real accelerators 🙂


  3. hmmm says:

    Has the LHC rediscovered the Standard Model then?

  4. lost says:

    DRL –
    “Lose the beam” –
    “The” beam is typically many bunches circulating around the circumference.
    (And obviously two counter-rotating beams in the LHC.)
    In the present case, possibly just one bunch per beam just to verify that the LHC works.
    I do not know.
    Anyway, to “lose a bunch” –
    It may hit the wall of the beam pipe (vacuum chamber) or some aperture.
    Possible reasons –
    – The steering went wrong during the energy ramp and the beam centroid went off-center (typically).
    – The bunch was injected badly and did not line up nicely with the reference orbit. (Then the beam would be lost immediately not at 700 GeV.)
    – There is also beam loss from beam-gas scattering. This is a slow process ~ diffusive. An entire bunch is not lost this way.

    During normal operations, after a fill is over the beams are `dumped’ by targeting them onto some beam stop. This is also a beam loss.
    Beams can also be deliberately aborted during emergencies (a quench?).

    When a hadron beam hits a target (wall, beam stop, …) it generates artificial radioactivity.
    This is at least one reason that accelerators are interlocked and everyone must be out before operations can begin.
    (Electron beams produce much less artificial radioactivity but they produce much synchrotron radiation ~ “bremsstrahlung” ~ also a reason everyone must be out.)

    Eventually several parts of the LHC will become radioactive. This is a fact of life for hadron accelerators.

  5. Pawl says:


    Would it be possible to give a quick summary of what the sub-screens, etc., in the vistars link you previously gave signify? Or give a link to an explanation? (I can work out some, but not all of it.) Thanks.

  6. Peter Woit says:


    I don’t know what the graphics visible on the LHC1 vistar are representing, maybe someone else does. The screen has semi-reliable info about whether the beams are in the machine, at what energy and what intensity. Perhaps the text messages from the operators are the most useful indications of what is going on.


    They’re still quite a ways from rediscovering the standard model (in the sense, for instance, of being able to see W’s, Z’s and top quarks)

  7. from CERN says:

    hmmm, for the moment LHC rediscovered the pion

  8. Ralph says:

    Re the graphics on LHC1 vistar these are normally BTV-something:

    From http://lhccwg.web.cern.ch/lhccwg/Bibliography/UsefulAcronyms.htm “BTV: Beam Observation TV Monitors based on Screens”

    From what I can make out, they have thin screens in front of the beam dumps, presumably with cameras pointing at them, and the images show the beam profile from a recent beam dump.

  9. Yatima says:

    And here’s how the LHC “beam dump” looks like. Useful when you have to get rid of your hadrons quickly:


  10. Martin says:

    Regarding the first publication: arXiv:0911.5430v1 [hep-ex] you mentioned.

    How stringent are the requirement for an arXiv publication?
    This paper just says that they’ve managed to achieve a few collisions and that 2 parameters are what they expected.

    Where’s the new physics? Which hypothesis were they testing?
    Surely they weren’t trying to falsify Holger B. Nielsen’s and Masao Ninomiya’s paper on “Search for Effect of Influence from Future in Large Hadron Collider” ( http://arxiv.org/abs/0707.1919 )?

  11. chris says:


    arXiv is a preprint server and as long as there is one endorser (basically everyone who has ever put a few decent articles on arXiv) you can upload your preprint there.

    also you should keep in mind, that accelerator physics and detector physics in itself is a topic. verifying that you have collissions in a new accelerator and that your new detector can make sense of them is worth a publication certainly.

  12. Paul Wells says:


    I think another reason for the rapid publication is that many of the people on the LHC teams are PhD students who need a publication of some sort to graduate and they have been waiting a very long time for LHC data. IMHO – good luck to them all !

  13. Yatima says:

    Apparently the LHC suffered a large-scale power failure, but apparently nothing bad came out of it:


  14. student says:

    You can expect similar Min Bias papers from all LHC experiments in the very near future. Alice was simply a lot more aggressive in getting the paper done quickly, but the DG of CERN is asking for all experiments to have them out soon.

  15. Bob Levine says:

    “I think another reason for the rapid publication is that many of the people on the LHC teams are PhD students who need a publication of some sort to graduate and they have been waiting a very long time for LHC data. IMHO – good luck to them all !”

    What I wonder is, just how much glory do you *really* get as approximately 1/800th author of a paper which, when the five pages of names and affiliations and the page and a half of acknowledgements are references are subtracted, comes to not quite five and a half pages? Is anyone’s career really going to be advanced on that basis?

  16. Peter Woit says:


    This has nothing to do with glory, just with many universities not wanting to award a Ph.D. to someone until the point where they have some real data to show.

  17. Me says:

    “Is anyone’s career really going to be advanced on that basis?”

    I can assure you, they do advance on that basis.

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