Positive charges in the nucleus

Discussion in 'Physics & Math' started by arauca, Feb 15, 2012.

  1. arauca Banned Banned

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    What are the distances in the nucleus between protons , and what is holding them together so they are not break away from nucleus
     
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  3. Robittybob1 Banned Banned

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    It is call the strong nuclear force.
    Wikipedia covers it quite well at http://en.wikipedia.org/wiki/Strong_interaction

     
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  5. arauca Banned Banned

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    That is nice , Then why neutron fall out from the nucleus and not the protons in case of radiation , does that means that the strong forces don't act upon the neutrons
     
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  7. Robittybob1 Banned Banned

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    It will have to do with they way they stack together. Some arrangements will have a lower energy level and be more stable than others. If it means it has to spit out a neutron to get there it will happen from time to time. They don't all react at once remember, radioactive half-lives etc.

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  8. Pete It's not rocket surgery Registered Senior Member

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    In neutron emission, what force gives the emitted neutrons their 'kick' away from the nucleus?
    Not EM or gravity, obviously.
    So is it the weak nuclear force?
    Or can the strong nuclear force be repulsive as well as attractive?
     
  9. Robittybob1 Banned Banned

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    It would be type of physical displacement I would say. Like squeezing a slippery orange pip and it flies off. The other neutrons/protons squeezing down on it eject it. Is that a good guess?

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  10. Pete It's not rocket surgery Registered Senior Member

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    Meets the common sense test.

    But it doesn't quite get to the answer.
    In the macro world, physical displacement is about the electromagnetic force between atoms and molecules.
    At this level, I think physical displacement could only be due to the Pauli exclusion principle.
    If so, then what force does the Pauli exclusion principle use to keep apart two fermions which are attracted to each other?

    Probably I'm asking the wrong question. I suspect I'm wrongly applying classical intuition to a quantum phenomenon.
     
  11. Robittybob1 Banned Banned

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    No you are on the right track
    Wiki on Pauli exclusion principle states
    When you try and fit two solid objects into the one place one has to fly off.
     
  12. Pete It's not rocket surgery Registered Senior Member

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    Thanks!
    But I've gone too far... I just tried reading the Exchange interaction, and now I have to scrape my brains off the ceiling.
     
  13. temur man of no words Registered Senior Member

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    I don't think it is some sort of repulsive force 'kicking'. My take is that the original nucleus is in some metastable state, and the separation of a neutron would be some sort of tunneling process to a lower energy state.
     
  14. temur man of no words Registered Senior Member

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    But this does not explain why neutrons rather than protons are ejected. The Wiki page has nothing on it. There is a page for proton emission and it says proton emission does not occur in nature. Why neutrons?
     
  15. Trippy ALEA IACTA EST Staff Member

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    Because the strong force is strongest between protons and neutrons.

    Oh, and there are two drip lines - only neutron rich (heavy) isotopes decay by emitting neutrons. Neutron poor (light) isotopes decay by electron capture, or proton emission.

    Addendum:
    Proton Emission on Wiki

     
  16. Trippy ALEA IACTA EST Staff Member

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    My recollection is that beyond a certain distance, the strong force becomes repulsive.

    Addendum:
    I got that the wrong way around. At distances <0.7fm it becomes repulsive. At 1 fm it is attractive, and begins to decay rapidly out to a distance of 2.5fm.
     
  17. Trippy ALEA IACTA EST Staff Member

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    And here's an animation of the strong force:

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  18. Pete It's not rocket surgery Registered Senior Member

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    That's very cool, and kind of hypnotic.
     

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