LHC Reaches 100/μb/s target for 2010

The Large Hadron Collider has reached its official 2010 target for peak luminosity of  100/μb/s or 1032/cm2/s . Massive Congratulations are due to all the teams at CERN who have worked incredibly hard this year to achieve this success!

This luminosity is 3.15/fb/year. The target next year is to collect 1/fb of data, but it is not possible to run at peak luminosity continuously so an extra margin is required. If they can run for 40% of the time during the running time allocated they really need peak luminosities of about 200/μb/s so they still have a little ground to make up.

The 100/μb/s has been reaches with 248 bunches by pushing to tighter emittances and better intensities. The next physics run will be with 300 bunches.

There are still three more weeks of proton running this year, so with the official target passed they can relax and use the time remaining for whatever seems most useful. That will include running to collect physics data before the winter break, pushing the number of bunches a little higher, and running various tests and scans that help them understand the machine better.

One last thing they might possibly try is something extra to improve luminosity. There are options to squeeze the beams to a lower beta* of 2m, or reduce the bunch separation to 75 ns or even 50 ns, but these might take time and result in less data collected for this year. If they don’t do these things now there should be time next year.

Whatever they, this year’s proton physics runs will be counted a great success.

Update (16 Oct 2010): In a short run last night with 312 bunches the peak luminosity was increased to about 135/μb/s. The filling scheme is 150ns_312b_295_16_295_3x8bpi19inj which means 312 bunches per beam with a 150ns minimum separation between bunches, 295 collisions per turn in ATLAS, CMS and LHCb, 16 collisions per turn in ALICE and 19 injections of up to 3 trains of 8 bunches at each go.

Tentative plans are to move to 360 bunches after three good runs at 312. Then they hope to try out a 50ns bunch spacing and 32 bunch injections so that they can go to 400 bunches or higher. They are also still hoping to collect 50/pb before stopping pp physics. Current total delivered is just over 20/pb. Whether they can get there, (or even go beyond) depends on how many running problems come up in the two weeks they have left, but with the goals for 2010 already met, anything extra is icing on the cake.


7 Responses to LHC Reaches 100/μb/s target for 2010

  1. Luboš Motl says:

    It’s been great 9.5 months but the year is not yet over, Phil! ;-)

    Congratulations to Lisi that his 248 bunches reached the 100/ub/s fireworks haha.

  2. Philip Gibbs says:

    Yeh, more than two weeks of pp physics and then Heavy Ions to look forward to before Xmas, but at least we wont hear people saying their targets are “overly optimistic” for a while. :)

  3. Luboš Motl says:

    Exactly. I think that there’s been too much of this deliberate attempt to lower the expectations – whatever motives people have to do so. This is on all fronts, from engineering to the analyses of the data (that are almost immediate, just like I expected).

    People have been preparing for similar moments for quite some time – engineers, experimenters, even phenomenologists. It is preposterous to imagine that they need to do all the work – planning and analyzing – now and from scratch.

    It also seems plausible that the number of possible “stop signs” is very limited – both for the increases of the LHC energy and luminosity as well as for the analyses of the data. Of course, a big catastrophe may always occur and plans may change. But if people actually have solved their homework as much as they can and they do not expect such tragedies, they should refrain from predicting them publicly.

    To some extent, the lowered expectations are a counter-movement against some typical things in the past – like overestimating the speed of construction and underestimating the costs that has taken place with many experiments. However, I would still argue that these worse-than-predicted scenarios occurred in stages of the projects that depended on bureaucrats or other non-physicists.

    When it gets to physics – and the engineering that is so close to physics – things become pretty rigorous and the full expertise of the people may show up.

  4. Lawrence B. Crowell says:

    I would imagine some of the caution has been heightened by the abortive start up two years ago. The less than dramatic expectations with time might reflect some desire to prevent a repeat of that type of problem, and conern that some technological demon might be waiting in the wings.

  5. Bill K says:

    I think much of the credit for this year’s success belongs to the new DG, who really has his feet on the ground and has capably deflected political pressure so that the engineers can do their job. To him also goes credit for the open policy that we see.
    From our side, I think it’s appropriate to temper our remarks – neither rosy optimism or doom and gloom, since the truth lies somewhere in between. The LHC’s successes have been very gratifying, but they’ve been hard won and not without setbacks along the way. Dismissing them as “niggles” I think is not entirely realistic.
    As far as attaining goals, 100/ub/s has not been the only goal. Another goal was 100/pb by year’s end. Currently we’re one-sixth of the way there. And another stated goal was to run with 384 bunches. Let’s keep things in perspective and not break out the champagne quite yet.

    • Philip Gibbs says:

      I agree that it has not been easy, it has obviously been hard work, but there have been no major setbacks this year. There have been many problems to resolve but these are expected. They have reached their target because they allowed enough time to cover resolving those problems.

      The only firm target they had for this year was to get 100/μb/s. They have formed many plans along the way that included the number of bunches as high as 768 and estimates for the total integerated luminosity they might reach, but I never saw such a plan last more than a few weeks before being modifed in some way. This flexibility has been an element of their success. They could never predict exactly how the LHC would operate best and have adapted the plans to suit its nature.

      For total integrated luminosity I have seen estimates of 50/pb and 70/pb and they could easily have hoped for more on occassions. If total integrated luminosity was their priority they could still get near these numbers.

  6. [...] foros nos han contado esta buena noticia, como Philip Gibbs, “LHC Reaches 100/μb/s target for 2010,” viXra log, 14 Oct. 2010; Tommaso Dorigo, “LHC Breaks Into 10^32 Territory,” A [...]

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