LHC run may be extended until end of 2012

Since the Large hadron Collider started physics runs early this year, the plan has been to run to the end of 2011 in order to collect 1/fb of data at 7 TeV. After that the collider would shut down for over a year to upgrade the magnets before allowing it to run at its full 14 TeV. But the plans at CERN for the LHC have always been somewhat flexible. Now with Fermilab hoping to extend the running of the Tevatron in order to scoop the LHC to the discovery of the Higgs, CERN are fighting back with talk of an extension of the current run that might find the Higgs even sooner.

This year the commissioning of the LHC has run somewhat better than hoped. In July when they stepped up the beam intensity they found it easier than expected to get to the designed count of 115 billion protons per bunch circulating in the ring. This meant that they could reach their target luminosity of 100/μb/s without stretching other parameters to their potential limits. By time the proton runs came to an end for the year, they had reached twice that target and were already trying out procedures to go to higher luminosity next year. With so much optimism in the air they have recently been talking of increasing the energy to 8 TeV during 2011. Projections suggest that they may be able to collect between 2/fb and 7/fb at that energy if they can live up to expectations of run efficiency. This would make the discovery potential of next year’s run much better than anticipated and so the payoff for continuing the run is much better. With such considerations in mind the CERN directorate is now proposing to extend the run to two years instead of just one, taking them to the end of 2012 before the long shutdown.

It remains to be seen how this will affect the decision at Fermilab to continue their run. Although they have expressed a strong wish to continue, they can only do so if they can find an extra $150 million and it is not clear where that will come from. Even if the money arrives as a new budget, other experiments at Fermilab will be held back by the continued running of the Tevatron. Not everyone thinks this is the best way forward for the lab.

As a successful run of Heavy Ion collisions enters its last few days at the LHC, the beam commissioning teams are now preparing their cases for how to run the collider when it starts up next year. A meeting at Evian on the 7th-9th December will be used to go over the possibilities with final details to be hashed out at Chamonix in January. The LHC is then expected to restart proton physics in February.

Meanwhile there will be some conferences to present any physics results they have using the 40/pb of data collected so far such as the “LHC First data” conference in Michigan on 12th December. (This does make me wonder how many more times the words “LHC” and “First” can appear together in a title.) We should not expect new positive results unless the physics gods are unusually kind with their favours.

As the year comes to an end let’s take this opportunity to thank CERN for allowing us such an open public view of the workings of the accelerator. We also thank the physicists who work on the detectors for bringing us their initial results so quickly. We look forward to so much more next year and beyond.

13 Responses to LHC run may be extended until end of 2012

  1. [...] la gran excusa es la búsqueda del bosón de Higgs y la SUSY. Y ahora nos lo vuelve a recordar Philip Gibbs: los rumores apuntan a que en Chamonix en enero se decidirá que el LHC funcione con colisiones [...]

  2. Luboš Motl says:

    In that case, the LHC would only be stopped on December 21st, 2012, when it would produce an exotic form of matter that would swallow the Earth, as implied by the end of the Mayan calendar on that day.

    This interpretation of the Mayan deities was also confirmed by the participants of the climatic catastrophic conference in Cancun that began by a prayer to Mayan Goddess Ixchel:


    All the participants promised to obey the orders and values of the pagan Goddess. They have denounced deniers such as Galileo Galilei and Isaac Newton who wanted to distort the right, Mayan way to approach Nature’s secrets.

    Christiana Figueres, the boss of UNFCCC, spent ten minutes crying in front of random young people


    and she clearly had the Mayan gods in her mind, too.

  3. Bill K says:

    Hello, this is the Grinch speaking. I want the Higgs boson as much as anyone, oh yes I do! But hearing suggestions like this worries me. There will always be pressure to go on gathering more data. Especially if the first 5/fb – 10/fb shows “hints” of a signal… who would have it in his heart to call a halt in that case?

    I would! In my opinion, they should stop NOW. This is a good time to stop. Spend 2011 doing the repairs. Get them over with, and so continue into 2012 with a machine that is fully operational. My understanding is that they would still not be able to reach 7 TeV, because of the magnet training issue, which has no known cause or cure, but could easily get to 6.5.

    • Philip Gibbs says:

      I think the extension is a good idea. The discovery potential for the next two years will be high for Higgs and Supersymmetry if the luminosity can be pushed up. I think physics badly needs these results soon. I’d like to see them push the energy higher in 2012 too. 10 TeV should be possible.

      Getting a new BSM result before the shutdown would be very helpful politically. If the upgrade is expensive some countries could pull out given the current economic climate. Having some results in hand and a signal that there is more to find would help to ensure the continuation of funding.

    • Bill K says:

      Phil, As we’ve pointed out before, 5 TeV has been deemed NOT possible without major repairs, but they might go to 4.5. Anyway, issues of safety aside, question: Wouldn’t it be a lot more difficult to analyze the results if they were split in half at different energies? I don’t think this is a naive question! If you had a year of data at 4.0 and a year at 4.5, combining the two would require you to know more about the behavior of the QCD background. Seems to be it would be far more sensible to just pick an energy and stick with it for the duration.

    • Philip Gibbs says:

      All the magnets were trained to go to 5 TeV per beam and it was only at the last minute that they decided to be cautious this year and run at 3.5 TeV. It is possible to run at 5 TeV and it is just the risk that has to be taken into account. Once they have data at 4 TeV the risk equation will change because there is less to lose and more to gain.

    • Bill K says:

      All right, well maybe you have access to information that I do not, or maybe I am misinterpreting what I see. Training the magnets is not the issue, it is the splices, and Chamonix 2010 dwelt on the risks at length, and the published papers leave no doubt that 5.0 TeV at that time was considered unattainable without doing a warmup and general repair.

      For example in the conference summary, https://espace.cern.ch/acc-tec-sector/Chamonix/Chamx2010/papers/SMFZ_10_02.pdf it says, “Without repairing the copper stabilizers, operation at 5 TeV is risky [4]. For confident operation at 5 TeV, the ‘outlier’ splices should be repaired, and a better knowledge of the input parameters is needed (i.e. RRR values for the cable and the bus). With the present input parameters the ‘limit’ splice resistances at 5 TeV are 43 μΩ (RB) and 41 μΩ (RQ). These values are close to the resolution limit of the measurements for the RBs
      at 300 K.”

      [4] refers to Koratzinos’ paper in the conference, which concludes:
      “Splices at cold (in the superconducting state) have been measured with excellent accuracy and do not pose a problem.
      Splices at warm (an indication of copper stabilizer continuity) have been measured in part of the machine and extrapolated to the whole machine using statistical methods.
      • worse splice measured: 60±1μΩ
      • worse splice known to exist in the machine: 53±15μΩ
      • worse splice extrapolated: 90μΩ
      The current knowledge of the interconnect splices excludes 5 TeV operation without major repairs after a warm up.”

      Again, what they are saying is that going to 5 TeV would at least require further resistance measurements for the RB (dipole) circuits in the warm state. Of course it may be that all of these conclusions have been discarded and superseded, but that’s what they said!

  4. Lawrence B. Crowell says:

    I have wondered myself why the LHC repairs are not performed after the current heavy ion run ends in a few weeks. We may not get physics done in 2011, but when things are back up in 2012 we might be better positioned for serious results.

    • Ben Young says:

      Lawrence, basically it’s a tradeoff between lower (but still unexplored!) energy data-taking now or further delay.

      Remember, the LHC machine exists only to provide collisions to the detectors, and the detectors exist only to feed data to the scientists. The scientists have been suffering from lack of any data to work on for years (the LHC schedule had already slipped considerably before the splice accident), and you want to accumulate enough to keep them busy for the shutdown.

      Scientists can’t be kept on the shelf until they’re needed, and the funding needed to maintain them depends on results. With no data in, the entire pipeline comes to a halt.

      There’s been a decade-long famine among LHC scientists trying to hold on until the feast of data begins. Feast-or-famine is a bad way to run things; better to maintain a steady flow.

      If you were to shut down now, there’s a risk that you’d have fewer physicists available to analyze 2012′s “serious results”. And the people squeezed out would be extremely bitter at having put a decade of effort into getting the LHC running only to run out of life support before the payoff.

  5. Compyblog says:

    LHC-Jahr beendet…

    Das kommt jetzt nicht besonders überraschend: Kurz nach 18:00 Uhr hat im LHC-Kontrollraum jemand auf den Knopf gedrückt, und die zirkulierenden Ionen-Ströme aus dem Teilchenbeschleuniger entfernt. Damit endet nicht nur der Ionen-Lauf, sondern auch die …

  6. [...] la gran excusa es la búsqueda del bosón de Higgs y la SUSY. Y ahora nos lo vuelve a recordar Philip Gibbs: los rumores apuntan a que en Chamonix en enero se decidirá que el LHC funcione con colisiones [...]

  7. [...] physicists at the LHC are trying to make up their minds whether or not it would be a good idea to extend next years run into 2012 to delay the long shutdown. This would give the LHC a better chance of finding the Higgs [...]


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