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Neutrinos going through neuclei?

  1. Nov 27, 2007 #1
    First let me relate that my understanding of quantum physics is rather shallow. What I'm looking for below is not some abstract mathematically response but rather a more spatially conceptual answer.

    Theory predicts every second supposedly 70 billion solar neutrinos pass through every square centimeter of the Earth facing the sun. And that almost all pass through the whole earth without interactions and in fact could pass through light-years of solid lead likewise. And in recent years these previously seemingly massless particles may actually have a mass estimated to be maybe 2 or 3 eV. Due to the extremely limited interactions of the weak force, finding out anything experimentally is very difficult so what is known is more apt to be theoretical.

    Now considering neutrinos that go through neuclear matter. Obvious a small percentage of those neutrinos per the radius of atomic nuclei are also going through each nucleus. That tends this mind of limited understanding to consider a few things that might be happening though I expect them to be rather naive interpretations:

    1)There is also a lot of empty space within what appears to possibly be solid nuclear particles.
    2) Or that either the path of neutrinos or the neutrons, protons, quarks etc involved in the strong forces keeping that all together somehow move aside for these neutrinos
    3) Or that the neutrinos punch holes right through whatever matter it meets.
    4) Some quantum tunneling type action occurs when meeting other matter so it simply appears on the other side as though it went right through.
    5) It somehow is not effected for any Pauli exclusion reasons thus goes right through whatever the substance is of other particles.

    Another similar question might be what happens when neutrinos go through neutron stars? And I expect the reason one does not read any explanations for what might be happening is there is it is simply too mysterious to form any hypotheses. However I'm sure some of you can come up with some possible explanations better than mine.
    Last edited: Nov 27, 2007
  2. jcsd
  3. Nov 27, 2007 #2


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    neither of your interpretations are "correct"

    The reason why neutrinos interact so weakly, in comparison with strong- and electromagnetic interaction. Neutrinos ONLY have weak interaction, i.e via the Weak Force, through the gauge bosons W(+/-) and Z(0). So that is the reason why neutrinos have penetration lenght in lead in the orders of light years.
  4. Nov 27, 2007 #3


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    (1) is basically correct. The mean separation between quarks in nuclear matter is about 10^-13 cm. On the other hand, a neutrino and a quark won't interact unless the distance between them is less than the Compton wavelength of a W, about 10^-16 cm. So to a neutrino, nuclear matter is mostly empty space.

    This discussion is, of course, greatly oversimplified. In fact the interactions of neutrinos with nuclear matter is important for understanding supernovae, and there has been a lot of work on it.
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