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Nuclear decay emission: deterministic modeling?

  1. Apr 14, 2012 #1
    Is it possible, in theory, that a radioisotope undergoing nuclear decay (eg. alpha particle emission) can be modeled so as to determine the origin and/or direction of the emitted particle? For instance, perhaps one could model nucleon interactions deterministically and observe that when the interactions occur in a certain way it causes an emission.

    If so, will this also work for gamma emission? Could you not only model where in the system the emission occurs, but its direction?
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  3. Apr 14, 2012 #2


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    Decay is a quantum mechanical process. Theory, in principle (since it is hard to solve strongly-interacting systems), can determine a partial decay rate for a nucleus for each decay mode. Beyond that, the decay is statistical, in the sense that there is no determined time for a single nucleus, but if we study a large collection of them, we can talk about the fraction of nuclei that we expect to have decayed in some period of time.

    We also can't really say where in the nucleus the decay started, since the nucleons are smeared according to the wavefunction. Again, this is a strongly interacting system, so we don't have exact wavefunctions, but we do know that the nucleons are not localized at points and there is even a large virtual particle contribution to the nuclear state.

    The direction of the emitted particle is a kinematical distribution dictated by conservation of energy and momentum. Since the nucleus is always allowed to recoil a bit, the momentum of the emitted particle is variable and hence so is its direction. Angular momentum considerations might make some directions more probable than others, but the precise direction is not deterministic.
  4. Apr 14, 2012 #3


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    Yes, it's possible. For example, Bohmian interpretation of quantum mechanics models ALL quantum processes deterministically.
  5. Apr 15, 2012 #4
    The obvious case where the direction of the emitted particle may vary is in β-decays of nuclei whose spins have been aligned within a magnetic field. Here, the direction of the field defines a reference direction in space against which other measurables can be plotted.

    A classic experiment was done using 60Co in a magnetic field to measure the anisotropy of the emitted βs, and hence confirm that the weak force violates parity conservation.
    Last edited: Apr 15, 2012
  6. Apr 15, 2012 #5
    Are the directions of d-d electronic transitions (photon emissions) also indeterministic in conventional quantum mechanics?
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