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Discrete protons and neutrons in nucleus

  1. Feb 9, 2012 #1
    What if: There are only discrete protons in the atomic nucleus combined with electrons (not the orbital ones) being shared,in some random manner, leaving a net positive charge. The two particles only become discrete with the known different characteristics when the atom is "smashed" and a proton escapes with an electron (neutron) or without (proton.)

    Should I assume that this possibility was disproved 100 years ago?

    Last edited: Feb 9, 2012
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  3. Feb 9, 2012 #2


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    This would not explain anything and would contradict a model that works extremely well.
  4. Feb 9, 2012 #3
    When I worked in operations at SLAC I had the good fortune to chat with researchers at lunch hour and other times. What with that, watching what was going on there, and reading a lot more, I began to think that there might very well be an unlimited number of different particles that could be produced, depending on what target is used, what you hit it with, and how hard you hit it.

    While I have been rather busy with other things in the 30 years since then, I haven't change my mind much on that subject. In fact some parts of string theory appear to suggest such a possibility.

    My next question along these lines would be which quark is it that makes up the electron that is released in neutron decay?

  5. Feb 10, 2012 #4


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    Last edited: Feb 10, 2012
  6. Feb 10, 2012 #5


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    This was in fact an early model of the nucleus, inspired by the existence of beta decay, in which a nucleus emits an electron. When quantum mechanics came onto the scene, physicists realized that the Heisenberg uncertainty principle caused problems in keeping the electrons confined inside the tiny volume of the nucleus. Also, there are some nuclei in which you can't get the total nuclear spin to come out right, with the assumed number of protons and electrons. Finally, it appeared that beta decay violated energy conservation, because the electron has less energy than one would expect based on the difference in masses between the initial and final nuclei.

    Around 1930 the current picture solved those problems: nuclei contain neutrons which decay to proton + electron + neutrino. About 25 years later, people detected neutrinos in beta decay, which convincingly confirmed this picture experimentally.
  7. Feb 10, 2012 #6
    Thank you for the historical information. Some I knew of, some not.

    Then would it be accurate to think of the presence of the mass and charge of the electron, however represented in the neutron, as having some bearing on the "status" of the quarks that make up the neutron as compared to the different "status" of quarks in a proton.

  8. Feb 10, 2012 #7
    Sort of. Both quarks and electon-type particles (aka leptons) also participate in the weak interactions (such as β decay). This involves another kind of charge called weak isospin. Particles that 'feel' the weak force can be in one of two states: weak isospin up or weak isospin down. You can think of this as analogous to +ve and -ve electric charges (except that weak isospin comes in half units, ie up = +1/2, down = -1/2). (In fact, the weak isospin also contributes to the particles' electric charges.)

    Electrons are weak isospin down. They have lepton counterparts, the neutrinos, which are isospin up.

    Protons and neutrons each contain 3 quarks, of two different types (flavours) called up and down. These have weak isospin charges corresponding to their names. The proton has two up quarks and a down; the neutron two downs and an up. When a neutron β-decays to a proton, one of its down quarks changes to an up, reducing its total weak isospin by 1. To balance the books, an electron and an antineutrino are given off, each having weak isospin -1/2.

    NB the above is very simplified and I have glossed over some important details, most notably that the weak force only affects left-handed particles. (Right-handed ones all have weak isospins of zero, but carry different numbers for another type of weak charge that results in their carrying the same electric charges as their left-handed counterparts.)
  9. Feb 11, 2012 #8
    I'm going to have to ignore the isospin for now as several hours of online searches have given me a much better understanding of several areas and principles of particle physics, but a REAL comprehension of the exact meaning of isospin still eludes me.

    Since quarks are elementary particles I am thinking the Beta decay expulsion of the electron and antineutrino must be the required form of dumping the "left over" charge, energy, and mass.

    The generation of one elementary particle from another still bothers me more than a little. Interesting that I had never thought of it in that particular way until just now.

    If the last few days are any indication, I have a lot more research/studying to do.

    It also occurs to me that I could be doing something else, like going to Hawaii. Chuckle.

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