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Are protons/neutrons magnetic? (Do they have North and South poles?)

  1. Jan 13, 2012 #1
    This has been on my mind for quite a while. The LHC controls and accelerates particles with superconducting magnets, but then is the idea of magnetic domains in magnetic materials wrong as it paints the picture that electrons are causing the magnetism because of their alignment? Which is it, the protons or the electrons (or another particle) that is responsible for magnetic characteristics?
     
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  3. Jan 13, 2012 #2

    Bill_K

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    Ralphonsicus, Particle accelerators like the LHC rely on the fact that the particles they accelerate are charged. Magnetic fields are used to steer the particles in a circular path and focus them to a very small collision point. Magnetrons (400 MHz RF cavities) are used to accelerate them.

    Protons, neutrons and electrons all have magnetic dipole moments, but the ones for protons and neutrons are about 1000 times smaller. So magnetic effects in materials are due primarily to the electrons.
     
  4. Jan 14, 2012 #3
    The origins of magnetic materials (what are called ferromagnets) is actually quite complex/abstract and very quantum mechanicy, surprisingly it's not actually due to the dipole moments of the particles. That beings said I don't really understand your question. What do magnet domain formation and confinement with superconducting magnets at LHC have to do with each other?

    Superconducting states are due to a very special way that electrons can, in a very funny way, interact with each other indirectly through the lattice of atomic nuclei. Superconductors have zero resistance which means that can carry enormous currents with very zero loss, this makes them amazing electromagnets which is why they're used at LHC. magnetic domain formation relates to how ferromagnetic phase transitions occur in ferromagnets.
     
  5. Jan 14, 2012 #4

    Bill_K

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    If you claim that ferromagnetism is not due to the alignment of electron dipole moments, please explain what you think it is due to.
     
  6. Jan 14, 2012 #5
    Exchange interactions. Which are actually interactions due to coulomb repulsion and the anti-symmetry of fermion wavefunctions. The energy of dipole moments is several orders of magnitude smaller than the ferromagnetic transition temperature in materials.
     
  7. Jan 15, 2012 #6
    Exchange interactions are responsible for the alignment of dipoles. But it is still the superposition of many aligned dipoles that are responsible for ferromagnetism.
     
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