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LHC Restart at 7 TeV

  1. Aug 7, 2009 #1

    Vanadium 50

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    The following is on CERN's website:

     
  2. jcsd
  3. Aug 7, 2009 #2

    mgb_phys

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    So on schedule for full power in December 2012 then ? (sorry)
     
  4. Aug 7, 2009 #3

    Vanadium 50

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    Isn't that topic that earns an automatic thread lock?

    Anyway, as they say, "It's not the end of the world if it runs at lower energy".
     
  5. Aug 7, 2009 #4

    Haelfix

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    Its definitely dissappointing, we've been hearing rumors about the lower power output for awhile now and its screwing up scheduling.

    What seems worse to me, is that there are still some structural problems within the LHC that could cause further quenches, the 7 TEV number while conservative is also influenced by politics and the possibility for further catastrophes is not remote.
     
  6. Aug 7, 2009 #5

    mgb_phys

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    It's also a slight amount of PR spin.
    It's not just achieving a particular energy that is the goal - it's getting a decent intensity at that energy that really takes the work.
    Even if everything had worked on day 1 it was still going to take years of tweaks to get to full beam power at 7Tev
     
  7. Aug 7, 2009 #6
    The Fermilab Tevatron first tried accelerating beam on the morning of July 3, 1983. By 6:00 PM that afternoon, they had reached 512 GeV. The next several months were used to trim up the machine, increase the current, and reach over 900 GeV. One advantage Fermilab had is that their ring is only 6.28 Km in diameter, compared to 27 Km for LHC. Another is that it was designed to ramp from injection energy to full energy in 20 seconds, and cycle once a minute, so it was an easy machine to tune.

    (From Fermilab weekly newspaper)
    [TEVATRON] REACHES GOAL, SETS ENERGY RECORD!

    by Thornton Murphy

    The [Tevatron] has reached its primary design goal: accelerating protons to 500 GeV in a ring of superconducting magnets. In fact, the energy was 512 GeV--a new world record for accelerators. The record was set at 3:37 p.m., Sunday, July 3, only 13 hours after the first serious attempt to accelerate beam above the injection energy of 150 GeV.

    News of this historic achievement spread rapidly-by telephone and telex to all quarters of the world. The Control Room rapidly filled with off-shift workers and other well-wishers as the champagne was broken out.

    The events leading up to this milestone followed the usual pattern of a long pause while a blockade to progress was diagnosed, followed by sudden leaps forward. Difficulties in achieving coasting beam at 150 GeV, reported two weeks ago, were finally tracked to a misdesigned flange in the C0 straight section and a Kimwipe left in the bore tube in A0. After the Kimwipe was removed on June 25, coasting beam was rapidly achieved. The rf cavities were proven capable of maintaining the bunching at 150 GeV and even accelerated the beam slightly.

    There followed a two-day down period for necessary repairs with the expectation that acceleration towards 500 GeV would begin soon after startup on June 30. Unfortunately, the weather did not cooperate. A lightning bolt struck service building E0 at 3 a.m. on Friday, July 1, damaging enough sensitive electronics to cause six hours of diagnosis and repairs, followed immediately by more lightning-induced trips around 9:30 a.m. The next night torrential rains found their way all the way to electronics racks.

    When all was finally ready to attempt acceleration, beam reached the top of the 250 GeV ramp on the very first pulse at 3:12 a.m., Sunday, July 3. After a shift of studies at that energy, the current ramp in the magnets was reset to 400 GeV and beam accelerated to that energy at 1:38 p.m. A "go for the record" spirit then prevailed; after readjusting the ramp again, the energy goal was exceeded amidst jubilation at 3:37 p.m.
     
  8. Aug 13, 2009 #7
    ... and the Tevatron took a long time to deliver significant luminosity as they had large problems with anti-proton production, containment and cooling. At least at the LHC we don't need fancy anti-protons.
     
  9. Aug 14, 2009 #8

    ZapperZ

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    This thread is not meant to be used as another "doomsday" thread. Those have been sufficiently addressed in many previous threads in this forum. There has been nothing new, and so, no new discussion on that topic is allowed in this one.

    Zz.
     
  10. Aug 14, 2009 #9

    tiny-tim

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    lightning?

    I didn't realise the Tevatron had been affected by lightning (in the service building).

    Are all the LHC's service facilities well underground, away from lightning?
     
  11. Aug 14, 2009 #10

    mgb_phys

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    Re: lightning?

    The beam and the detectors are well underground, there is still a lot of buildings and equipement on the surface. Switzerland doesn't suffer from lightning to the same extent as the midwest.
    I think the main complaint from high energy colleagues (that is people who work in high energy physics - not just those that drink too much coffee) is that every time there is a warm spell the AC fails and all the computers get shut down

    Traditionally CERN doesn't run in the winter to reduce the power usage in the area.
     
    Last edited: Aug 14, 2009
  12. Aug 14, 2009 #11

    tiny-tim

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    Re: lightning?

    So the LHC will work perfectly :approve: … except in the winter and the warm weather? o:)
     
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