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Gravity effects in particle accelerators

  1. Apr 5, 2013 #1
    Is the effect of gravity ever considered in particle accelerator experiments? I would think not with all the high energy, velocities, and stong electric fields in use. But I am interested if gravitational effects have ever been considered or adjusts made to compensate for gravity's downward pull on perticles.
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  3. Apr 5, 2013 #2


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    In all of the modelling done to design particle accelerators, components, diagnostics, etc...etc., there have been zero consideration to gravitational effects. It is simply way to small to have any kind of measurable influence.

    If you look at the typical particle tracking codes that are used, such as PAMELA, PICT, etc., you'll see that these are all electromagnetic codes, with zero consideration for gravity. So far, these have worked quite well, or else they wouldn't have constructed all these particle accelerators all over the world (note that the overwhelming majority, i.e. more than 95%) of particle accelerators currently in operation have nothing to do with high energy physics experiments. Furthermore, the field of accelerators physics deal more with classical E&M than with high energy/particle physics.

  4. Apr 5, 2013 #3
    Why would g be any different for a particle than it would for a macro sized object? Or what were you were referring to as being too small? I know very little about particle accelerators, but I'll take a guess and say you were referring to the time interval.

    Ah, never mind the questions, unless you just want to elaborate. If your particle accelerator were located on a neutron star then you might have to consider the gravitational effects. But on earth the effects are too small to make a difference. :)
    Last edited: Apr 5, 2013
  5. Apr 5, 2013 #4


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    Imagine two parallel plates 0.1 m apart, with a potential difference of 1.0 V between them. The electric field in the region between the plates is 10 V/m, which is much smaller than you would find in a real particle accelerator.

    Place an electron between those plates. Calculate the electric force on it. Calculate the gravitational force on it. Compare the two forces.
  6. Apr 5, 2013 #5
    But a particle in a particle accelerator travels much farther than 0.05 meters. Shouldn't the time interval play a role here?
  7. Apr 5, 2013 #6
    In particle accelerators, the effects of gravity cant be removed but are usually neglected as they donot cause any appreciable change in the value of quantites of interest.
    Gravitational forces on subatomic particles are neglegible as compared to the other forces present around.
    Mostly since a very large number of calculations are performed, the effects of gravity in the final statistical output is compensated as experimental error.
  8. Apr 5, 2013 #7
    gravity and particle accelerators

    Yes the earth's gravitational acceleration, g, should not make any difference. But has any testing ever deliberately been done to prove that subatomic particles with opposite charge respond to gravity in the same way. Relativity explains a lot as a function of mass and warping space-time. But has interaction with gravity and electric charge been absolutely ruled out. Does an electon fall at the same rate as a proton? We assume so, yes. But have any experiments validated this?
  9. Apr 5, 2013 #8


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    You are now changing the topic.

    For your information, the Advanced Photon Source at Argonne started out its life as a synchrotron light source using positrons. The beam dynamics were done the same way as it would for elecctrons. This means that all the codes and simulations were the same for electrons, except for the sign change in the charge. And in a storage ring, it has to "live" for quite a long time. The effects of gravity was never part of the consideration of the dynamics of the positron beam. And as far as I know, it is either for the planned next-generation e-p collider.

    I'm not sure why electron has to fall as the same rate as proton, since they have very different masses! Are we talking about the "Galileo drop stuff from the Leaning Tower" scenario, or are you talking about gravitational forces of different masses? We already have experiments on neutrons falling in a gravitational potential. Is that good enough?

  10. Apr 5, 2013 #9
    So your question is about the equivalence principle as it relates to electric charge? I do not know of any past experiments of the type you are referring to. But I have read about some proposed experiments, including this one designed to test the earths gravitational effects on antimatter.

  11. Apr 5, 2013 #10
    The link you posted describes the AEGIS Experiment at CERN. This experiment studies the effect of gravity on antimatter. If gravity effects antimatter differently than matter, we may be able to prove the asymmetry between matter and antimatter.
  12. Apr 5, 2013 #11
    Yes, that is the goal. But it's also a test of the WEP. It's the closest thing I could think of that relates to the OPs question. I also remember reading about another proposed experiment to test the earth free-all of antimatter. But I can't seem to find it at the moment.
  13. Apr 6, 2013 #12
    Frame dragging is a gravitational effect.

    Apparently is was the neglect of this effect that resulted in the infamous FTL neutrino debacle.

    So it seems that in certain circumstances gravitational effects must be considered.
    Last edited by a moderator: Sep 25, 2014
  14. Apr 6, 2013 #13


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    The cause was a loose connector:
    Last edited by a moderator: Sep 25, 2014
  15. Apr 21, 2013 #14
    Can anyone direct me to a particle accelerator that can emit a horizontal beam of electrons or protons down a final linear track 5000 meters long. The final track must be electrically shielded so only gravitational effects (the downward pull of gravity at 32.2 f/m2) are acting on the beam. The energy requirements will be around 5 Kev for electrons and 5 Mev for protons.
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