LHC end of run update

Today is scheduled as the end of proton physics at the Large Hadron Collider and the last few fills are circulating this morning. The integrated luminosity recorded this year will end at about 5.2/fb each for CMS and ATLAS, 1.1/fb for LHCb and 5/pb for ALICE. For the remainder of this year they will return to heavy ion physics until the winter shutdown.

The good news this year has been the high luminosity achieved with peaks at 3.65/nb/s. This compares with the expectations of 0.288/nb/s estimated before the 2011 run began. The higher luminosity has been made possible by pushing beam parameters (number of bunches, bunch intensity, emittance, beta*) to give better than expected performance. The not so good news is that out of 230 days that were available for physics runs only 55 (24%) were spent in stable beams. This was due to a barrage of technical difficulties including problems with RF, Vacuum, cryogenics, power stability, UFOs, SEUs and more. There were times when everything ran much more smoothly and the time in stable beams was then twice the average. The reality is that the Large Hadron Collider pushes a number of technologies far beyond anything attempted before and nothing on such scales can be expected to run smoothly first time out. The remarkable amount of data collected this year is testament to the competence and dedication of the teams of engineers and physicists in the operation groups.

After the heavy ion runs they will start looking towards next year. There will be a workshop at Evian in mid December to review the year and prepare for 2012.  Mike Lamont, the LHC Machine Coordinator will be providing a less technical overview for the John Adams Lecture on 18th November.

14 Responses to LHC end of run update

  1. Nessuno says:

    Hi Philip,
    normally one makes a testament when expecting to die soon. I certainly hope and wish this is not the case for the OP people!

    • Philip Gibbs says:

      If that were the meaning in use here it would be the data collection that was about to die and that would be even worse!

  2. ondra says:

    Great LHC proton run in 2011, i think while collecting maximum amount of luminosity wasnt always the priority, for example last two weeks, the results are great. If electrical network and cryo performs good in next month i think we can expect nice ion results too.
    Btw ATS dry test at beta 0.1 m (0.55 is nominal w/out ATS).

    • Philip Gibbs says:

      Yes the running in the last few weeks was great (except the last days) They were able to maintain the same rate of luminosity gathering while doing extra MD tests at the same time.

      It would be good if they could use ATS next year but I don’t want to get my hopes up. They have said it is for later. My dream (possibly realistic) scenario for next year would be 8 TeV with 25 ns spacing and 0.3 beta*. If they can’t go to 0.3 beta* I think it would be better to stick at 50 ns and maximize bunch intensity and running efficiency. However I don’t have all the information and the optimum strategy may be different.

      • ondra says:

        Well last few weeks September/October run showed that 10 fb-1 next year are within LHC reach even if you stay on current values and if you can get higher running efficiency maybe even more, especially for LHCb. Right now it seems SEU and electrical network instabilty, you loose cryo, magnets etc., are main problems. UFOs didnt cause too many dumps.
        From energy point of view we will know what splice resistance measurement show but they are very much concern for the machine protection. I guess it would be nice to gain real experience with 25 ns to be ready for 14 TeV machine.

      • carla says:

        It’s interesting comparing the running of the LHC this time last year and what actually happened. 50ns certainly wasn’t on the cards and the best hoped for was running at 0.2/nb/s to collect 1/fb.

        Looking back to your 25th October 2010 “LHC Back With Gusto”, doesn’t it make you laugh at the part where it says “In another run with 368 bunches still ongoing this morning, they have collected 3.8/pb in just 6.5 hours”, when they manage 65/pb in October 2011?

        My guess is they’ll continue to push the LHC with still more surprises and at least doubling the 10/fb that is expected of it next year.

      • ondra says:

        That certainly was the experience carla. Actually their aim for peak lumi next year is around 6/nb/s but maybe even closer to nominal 10/nb/s. But higher running efficiency can give you much more data too.

  3. [...] gezien van Higgs bosonen of supersymmetrie, maar men hoopt die in 2012 wel te kunnen zien. Bron: viXra. Deel deze [...]

  4. Nemo says:


    is there still a lack of seminar dates on the next Higgs data announcements?

    • Philip Gibbs says:

      There are always places where they can announce results if they want to but I think they have moved into a slower gear compared to this summer. I have heard that they will have results ready for approval by December but it may take a long time to review them. They may also want to prepare a full combination if the individual plots are not conclusive. I have heard it said that the full 5/fb results will be announced at Moriond in March.

      It is still possible that some further 2/fb or even 3/fb plots could be shown at HCP 2011 this month. They certainly have them ready so if they don’t show them it is because they are too inconclusive. They should at least show a combination of the results shown at Lepton-Photon.

  5. To Philip Carter:

    Happened just five minutes ago to add a posting about the possible variation of fine structure constant in cosmological scales to my blog.

  6. nameab says:

    Do you hear about what is new physics?Is atomic medels wiii return to the electron orbital motion?


Get every new post delivered to your Inbox.

Join 270 other followers

%d bloggers like this: