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CERN Operating at Half Power

  1. Jul 10, 2012 #1
    I was reading many articles last week about the Higgs Boson discovery and I noticed a passage in one of the articles saying that the accelarator at CERN has been operating at half power since it was put on line. Is that a true statement? Anybody? Do they ever intend on running at full power? If they found the Higgs Boson at half power that implies there may be more interesting discoveries at higher powers, if any. The article also said they intend to shut down CERN for maintenance at the end of the year.
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  3. Jul 10, 2012 #2


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    My understanding (but I can be wrong) is that during the maintenance they will do some changes that will allow to double the power. So "half the power" means "half the planned maximum power".
  4. Jul 10, 2012 #3


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    Thanks to multiple hardware problems, mainly soldering flaws, the LHC has been operating at reduced power, 3.5 TeV per beam in 2011 and 4.0 TeV in 2012. The "long shutdown" to make the necessary repairs has recently been postponed until Q2 of 2013, and will likely last all of 2013 and 2014. The planned power of 7 TeV looks unattainable, and further operation is expected to be at 6.5.
  5. Jul 10, 2012 #4


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    "Power" is a bit misleading, as it has a different meaning (energy per time). The relevant quantity is the energy per proton, for numbers see Bill_K. While they want to begin with 6.5 TeV per proton in 2015, the 7 TeV are still planned, as far as I know.

    You are right, the higher energy could give a lot of new discoveries - mainly (possible) particles which are too heavy to be produced with the lower energy.
    Concerning the future of LHC (2025+), one option is an upgrade of the magnets to get an energy of ~16.5 TeV per proton.
  6. Jul 11, 2012 #5
    Almost as good as the Superconducting Super Collider's planned energy of 20 TeV per proton.
  7. Jul 11, 2012 #6
    It's at half energy for safety reasons. They want to make sure it can handle full energy before they try to give it full energy. Remember the LHC was delayed for a year because when they first ran beam tests one of the magnets 'sploded.

    As I understand starting at less-than-design-spec energy is normal for accelerators. Also the current energy is (apparently!) more than sufficient to perform the initial function they hoped the machine to fulfill, i.e., finding the Higgs Boson.

    Disclaimer: I am not a physicist
  8. Jul 11, 2012 #7


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    This paper from the Chamonix 2012 Conference discusses the prospects of 7 TeV, and suggests it might be achieved after the Second Long Shutdown (year 2018). I think even this is hyperoptimistic!

    The situation is basically unchanged. Superconducting magnets require "training" to meet their design performance, which means repeated quenches - sudden warming and loss of superconductivity. This is a violent process and not without risk. As the paper points out, four of the magnets were partially damaged by this during early testing and will need replacement in the First Long Shutdown, 2013-2014.

    But here's the problem - thanks to defects which have not been understood, the magnets produced by one manufacturer (the "Firm3" magnets) require a far larger number of quenches than expected. Perhaps as many as 900 quenches in all would be needed to reach 7 TeV. Each quench and recovery is time-consuming, taking about half a day. In other words, a full year devoted to nothing but quenches! In my opinion, 7 TeV simply will not happen.

    The paper even says that due to the training problem it might be necessary to operate at 6.25 TeV rather than 6.5 for the 2015 run.
  9. Jul 12, 2012 #8
    Thanks to all who replied with their input. Even going to 6.5 TeV is a big jump from present power levels. I hope we find new discoveries.

    As far as the magnets, they need to develop room temperature superconducting materials. It is a holy grail of the superconducting community just as cold fusion is to the fusion power community.

    Going to 16.5 TeV has got to provide new discoveries if they can get to that power.

    But it sounds like the technology is not their yet to provide those power levels reliably.
  10. Jul 13, 2012 #9


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    If there are no new particles, no new particles can be found [STRIKE]unless you work at CDF[/STRIKE].
    Sure, some "low-energy" studies (mainly W,Z,Higgs,top) will profit from the higher cross-section, but an increased luminosity is more important there.

    I would expect that room temperature superconductors - if they are possible - are very sensitive to magnetic fields. They might be nice for power transmission, but not for hadron collider dipole magnets. There are superconductors which work with liquid nitrogen already - a big step compared to liquid helium, which is much more expensive. However, the LHC does not use them to generate the strong magnetic fields.
  11. Jul 13, 2012 #10

    I agree, if we have found all the particles that are predicted, then no new particles. Maybe they can find evidence of strings at the higher energy level????

    Yes, liquid nitrogen is a big step forward for superconductivity.
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