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Worlds largest particle accelerator

  1. Oct 20, 2006 #1

    taylaron

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    i hear that CERN is under construction and is to be the next "worlds largest paricle accelerator"
    now, fermilab can accelerate particles up to near speed of light.
    if the speed of light is the cosmic speed limmit, how is building a bigger one going to be any better
    i know theres a reason
    prehaps the whole point is to go beyond the speed of light. because that is the maximum speed where particles can stay together. is that it?
    are particles in these accelerators in fermilab and CERN going faster than the speed of light?

    http://www.symmetrymagazine.org/cms/?pid=1000359
    :surprised
     
  2. jcsd
  3. Oct 20, 2006 #2

    ZapperZ

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    Let's do this via simple classical physics.

    Since kinetic energy is proportional to the square of velocity, you can increase the velocity by just a little bit and you have increased the kinetic energy by a lot. This means that going from 0.9999c to 0.999999c can make a difference in ENERGY that is being gained.

    That is what the LHC at CERN is going to accomplish over the Tevatron at Fermilab. The center of mass energy per "parton" will be considerably larger than the Tevatron.

    Zz.
     
  4. Oct 20, 2006 #3

    Doc Al

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    The point is to be able to accelerate particles to greater kinetic energy (relativistic kinetic energy--which is not simply proportional to velocity squared). The speed limit is still the speed of light.
     
  5. Oct 21, 2006 #4

    DaveC426913

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    So, what is the "worlds largest particle", and how fast can they make it move in this "accelerator"?:biggrin:
     
  6. Oct 21, 2006 #5

    selfAdjoint

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    They don't accelerate the world's largest particle, they accelerate massive particles that are easy to come by, long enough lived to last through the accelerations (which takes a lot of laps arounf the circular tack) and they collide them with their antiparticles to make a high energy spray of other particles which are then fed to the detectors.

    And I want to say something about those detectors; the whole point of all that acceleration is to provide input to these "experiments" as they are called. Designing and building them, planning all the interpretation, writing the software, so on and so on, takes years out of the lives of hundreds of people, including usually 20 to 50 high level ones. It is the detector physicsts, not the beam physicsts, who get the exciting results that are reported in the newspapers.


    But to get back to those accelerated particles, at Fermilab they use protons and antiprotons, and I believe the LHC at CERN is going to do the same. After all LHC stands for Large Hadron Collider, and the only hadrons with lifetimes longer than a gnat's eyeblink are the proton and neutron; and the neutron, being uncharged, is hard to focus.
     
  7. Oct 21, 2006 #6
    One of the project that's going to use the detector being built (or already built?) is called ALICE (A Large Ion Collider Experiment), and the goal is to collide two lead ions together to create a QGP. So the mass is much bigger than proton/antiproton.

    There are alot of softwares for particle physics designed by CERN. I will be using GEANT4 for my honours project and that's developed by CERN. It is really a big organization and I would really love to be a part of it once I'm done my studies.
     
  8. Oct 21, 2006 #7

    DaveC426913

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    Note to SelfAdjoint: get humouradar checked. Seems to be futzing out particularly around emoticons such as::biggrin:
     
  9. Oct 23, 2006 #8
    You are right that the Tevatron at Fermilab collides protons and antiprotons, but the LHC will collide just protons together. This is because protons are easier to make and at these high energies they are predominantly composed of gluons anyway (so the LHC is really a gluon collider) so a proton and antiproton look pretty much the same.
     
  10. Oct 23, 2006 #9

    selfAdjoint

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    Thanks for the info. Boy I'm sure glad I prefaced that wrong statement with the weasel qualifier "I believe". So the LHC should be called the LGC? Or does gluon start with an H in German or French or Esperanto or whatever?
     
  11. Oct 23, 2006 #10

    taylaron

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    whats the reason that we cant accelorate particles that are "too big"
    is it because of their charge, their weight, what?
    all we do to keep these miniscuel particles aligned in these accelorators are magnetics, am i correct? having the oppositely charged walls around the opposite charged particle, forcing it in the middle. then simply magneticly attracting the particle to the maximum speed for the complex and BANG! you've got particle guts everywhere.
    can you simply "smash" a neutron (negitive charge) into something?
    since the neutron is neutrally charged, does that make it not useable?


    and what happens when these particles collide at near speed of light. obviously they seporate into their contents (quarks etc.....) but how do you detect them, espcially if they have no charge. how can we detect something that small that is not charged (+ or - )???????? -> neutrally charged:eek:

    and can we "smash" these particles together (eg. quark and a quark. to see what a quark is made of) or is it almost impossible to "keep" these particles for the duration of the next experiment?
     
  12. Oct 23, 2006 #11
    The neutron, being neutral, is very difficult to accelerate. But in principle, if you had them going fast enough, they would collide very similarly to a proton. As I said before, the proton is mostly gluons at high energy, and so is a neutron, so it would be (mainly) the gluons which interact.

    As for seeing substructure of quarks, it woud depend on the size of the constituents. The collider probes a size equal to its de broglie wavelength, which decreases with energy, so to probe really small thing you need really high energies. There has been no evidence of substructure in quarks at the probed energies so far (a few hundred GeV) but who knows for the future...
     
  13. Oct 23, 2006 #12
    There are some interesting reactions from the quarks too, but they are quite rare. The most interesting is probably when the quarks radiate a W-boson each, which then fuse to form a Higgs boson. This is a nice clean Higgs signal, even though it has a very small rate.

    And they speak French in Geneva... (CERN is actually half in France too.)
     
  14. Oct 25, 2006 #13

    taylaron

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    in a circucular particle accelerator, why does it matter how big it is when you have as may revolutions as you need. dispite the size of the atom being accelorated?
     
  15. Oct 25, 2006 #14

    ZapperZ

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    A smaller circular accelerator will bend the particle more than a larger one. This means that the particle will lose energy due to the bending path (a circular motion is an accelerated motion, remember that from basic mechanics). So while you're adding more and more energy to it, it is also losing more and more energy as it gets faster via this synchrotron radiation.

    Such a thing is OK for a synchrotron ring, but not OK for a particle collider.

    Zz.
     
  16. Oct 26, 2006 #15

    taylaron

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    so thats why its "the bigger the better"
     
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