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(why) is an electron indestructible?

  1. Apr 13, 2014 #1

    bobie

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    I suppose they tested collisions between electrons and protons/nuclei in powerful colliders.
    I never read of an electron breaking up (like a proton) even at high energies, if that is excluded, why so?
    Thanks
     
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  3. Apr 13, 2014 #2

    UltrafastPED

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  4. Apr 13, 2014 #3

    bobie

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    Is a neutrino or quark indesctructible?
     
    Last edited: Apr 13, 2014
  5. Apr 13, 2014 #4

    jtbell

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    As far as we know now, the fundamental (indivisible) particles are the electron, muon, tau, the three neutrinos, the six quarks, the W, the Z, the photon, and the Higgs.
     
  6. Apr 13, 2014 #5
    Hmm... What would happen if you feed electrons into a particle accelerator and collided them in that case?
     
  7. Apr 13, 2014 #6
    The energy of motion of the electrons will turn into other particles, just as the case for the protons and/ore Pb-nucleus in the LHC, ore any other high energy particle accelerator in that case.

    The accelerator before The LHC actual collided electrons and positrons together.
    http://en.m.wikipedia.org/wiki/Large_Electron–Positron_Collider
     
    Last edited: Apr 13, 2014
  8. Apr 13, 2014 #7
    You forgot to mention gluons. And off course, there is the possibility that other particles exist, but we haven't found them yet.
     
  9. Apr 13, 2014 #8
    Also note that electrons cannot be broken but they can be annihilated.
     
  10. Apr 13, 2014 #9
    You don't seem to understand what constitutes a 'fundamental' particle. A fundamental particle is roughly speaking one with no internal structure. I have no idea how you would define "indestructable" when it comes to sub-atomic particles, so I don't believe your question has meaning. Particles can and do convert from one to another → as long as the Conservation Laws are obeyed. Given enough energy, an electron and an anti-electron (positron) can create a proton and an antiproton. E= mc² + ½mv². So, velocity can be 'converted' to mass.
    Momentum, charge, and a couple of other conservation laws must be obeyed. For related topics look up neutrino oscillations and Feynman Diagrams. We don't use an accelerator to "smash apart" sub-atomic particles (unlike atom smashers of yore), we use them to accelerate (give energy to) the particles so that other particles (more massive, generally) can be created. The Higgs boson, for instance, didn't take 40 years to discover because it was so 'small' (whatever that means) but because it was so massive. Sub-atomic physics is not intuitive. Size in terms of volume, diameter, length, has little meaning and generally when talking about 'size' physicists mean 'mass' (previously known as rest mass).
    The nearest thing to macroscopic 'size' in sub-atomic physics is cross-section (or scattering cross-section). It is an area (cross-section) where two particles passing by one another are likely to interact (collide). The important thing about the concept is that cross-section varies depending on which particles you are considering. They are not additive, an electron has a different cross-section when it comes to neutrons than it does with protons, than it does with electrons. Cross-section is NOT a property of a particle, but a property of the pair (inseparable).
     
    Last edited: Apr 13, 2014
  11. Apr 13, 2014 #10

    bobie

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    Thanks, of course I was referring to mass particles taken individually, and not to annihilation.
    Now,
    - is there any difference in substance of a neutrino , an electron and a quark?
    - is it possible that a neutrino is a trillion (or so) part of an electron and that its charge is so small that is undetectable?
    - a quark just a fracion of a charge but its mass is greater than the electron, any idea of what it is made of or about the difference with an electron? can you collide quarks?
     
    Last edited: Apr 14, 2014
  12. Apr 14, 2014 #11

    UltrafastPED

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  13. Apr 15, 2014 #12

    bobie

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    Could someone answer this (probably stupid) question?
     
  14. Apr 15, 2014 #13

    Simon Bridge

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    If you are thinking that maybe the electron neutrino is evidence of an internal structure for an electron - the answer is "no" it isn't.
    Did you read the article on fundamental particles?
     
    Last edited: Apr 15, 2014
  15. Apr 15, 2014 #14

    Simon Bridge

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    That is correct. Also colliding electron beams.
    I think 12GeV is the record for electrons. No bits so far.
    http://phys.org/news/2014-04-cebaf-gev-commissioning-milestone.html

    Like you said: it has never been observed.
    Does not happen.

    If you mean "why doesn't it happen?" - because that is the way things are.

    Should some interaction be observed which indicates internal structure, then important chunks of the standard model will need to be rewritten.
     
  16. Apr 15, 2014 #15

    bobie

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    The article says that in some cases it can separate in quasiparticles.

    But,no, I was not thinking that, I was thinking more of a quark being a fraction of a charge, and was asking if such a tiny fraction (one trillion or less) can be detected.
     
  17. Apr 15, 2014 #16
    No. The neutrino was hypothesized to account for missing energy when a neutron decays into a proton and electron.

    From http://www.laradioactivite.com/en/site/pages/Neutrino_Hypothesis.htm
    “Swiss physicist Wolfgang Pauli postulated the existence of an electrically-neutral, low mass (at most 1/100 the mass of the proton) particle that would be emitted along with the beta particle. This hypothetical third body could then take away whatever energy was not given to the beta particle; solving that most vexing of issues.”

    So the neutron decays into a proton, electron, and antineutrino. We know with a high degree of accuracy that the charges of the electron and proton are always the same. That means that if the neutrino were to have any charge, as you propose, then either the electron or positron could have an irregular charge, and that would be bad.
     
    Last edited: Apr 15, 2014
  18. Apr 15, 2014 #17

    bobie

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    Thanks, Mike, I was not proposing, I was just wondering if such a small charge could be detected, as in another thread I was told that the intrinsic spin of a free electron is too small to be detected.
    Do you know if you can collide quarks?

    BTW, why cannot the missing energy in a proton (so small , anyway) cannot be acoounted for as extra KE ?
     
  19. Apr 15, 2014 #18
    If you are thinking of colliding two single quarks into each other. then the answer is no, because quarks can never be isolated into single quarks in the first place.

    You can find info on this by searching for "confinement". Basically, the energy it takes to separate two quarks would be enough to create another quark/anti-quark pair.
     
  20. Apr 15, 2014 #19
    If you look at the second graphic in the article I linked to, you can see that based on the direction that the proton and electron take, momentum is not conserved. Fill in the blank for the missing momentum, and you have the neutrino.
     
  21. Apr 15, 2014 #20

    bobie

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    So, the only elementary particle that can exist on their own (even for a short time) are leptons?
    Can you tell me why leptons like muon are considered elementary although they are made up by really elementary particles like electrons and neutrinos?
     
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