During 1991 I was studying Imaging Science at Curtin University of Technology and came across a book compilation of various scientific papers at the “Geo_Cosmic Relations: the Earth and its macro environment. Proc. first Int. long., Ed. Tomassen et. al. Purdoc, Wageningen, Holland.
One paper caught my eye: The Possible Gravitational Nature Of Factors Influencing Discrete Macroscopic Fluctuationsm, by N V Udaltsova, V.A. Colombia and S.E. School[Shnol], Physical Biochemistry Laboratory, Institute of Biological Physics Acad. Sc. USSR, 142292 Puschino, Moscow Region (USSR).
It contained some results of alpha particle emission of plutonium 239 over a period of time.
As gravity seems to be somewhat problematical in mineral exploration activities I wonder whether radioactivity is moderated by something else, say the Earth’s electric field as suggested by the late Ralph Juergens in an afternote
The conventional picture of the energetics of alpha-decay is shown by the heavy, solid lines in Figure 2. Inside the nucleus is a potential well — a region in which particles can move freely without the action of forces, yet which they cannot climb out of so long as their individual energies are less than the height of the sides of the well. At the top of the potential well the vertically rising potential line reverses sharply and gives way to a curve, steeply descending at first but gradually leveling out with distance from the nucleus.
This curve is a hyperbola, a form dictated by the electrostatic nature of the forces at work in this region; the curve is, in a sense, a curve of electric potential (multiplied by the constant electric charge of the alpha particle). The descending curve becomes flatter and flatter as it approaches (becomes asymptotic to) a horizontal datum line that is, by the same reasoning, essentially a representation of “zero” electric potential as well as potential energy.*
[*Unfortunately, but unavoidably, the terms potential (energy) and electric potential appear repeatedly in this discussion; I have tried to clarify matters by using the full term, electric potential, in each instance where electric potential is meant except that—Earth potential- is used in the electrical sense to avoid an awkward term such as—Earth electric potential.”]
According to experiments best explained by Gamow’s wave mechanics, an alpha particle escaping from an unstable (radioactive) nucleus does not actually climb all the way over the potential barrier rising above the datum line. Instead, it tunnels through at some level below the top. For example, though the barrier at the boundary of the U-238 nucleus rises past 9 million electron-volts (mev) above datum, alpha particles emerge from this nucleus with energies of only about 4 mev.
And since their final (observable) energies are due entirely to electrostatic repulsion in the region outside the barrier, they evidently make their way through the barrier at a level corresponding to 4 mev.
But what is the significance of the datum — the “zero” of electric
potential — from which these energies are measured? Clearly, since the data dealt with are derived from terrestrial experiments, this “zero” can be nothing other than an arbitrary value assigned to the electric potential of the surface of our planet — Earth potential.
What, then, if this datum should be shifted – raised or lowered with respect to the nuclear potential well, whose dimensions are apparently unrelated to electric forces – by a sudden change in Earth potential?
The Earth appears to be strongly charged with negative electricity, so that its surface electric potential is low, which is to say, highly negative. Suppose, then, that Earth potential is suddenly lowered by just 1 million volts – this, in all likelihood, an almost negligibly small fraction of the planet’s “normal” negative electric potential.
The potential (energy) curve outside our radioactive nucleus
presumably must now change and take the form of the dashed curve in the figure. Staying with our example of an atom of U-238, we find that an escaping alpha particle (following the same tunnel as before) emerges to be accelerated through a voltage drop and to a final energy half again as great as before – to about 6 mev. Reference to Figure 1 (main text) suggests that we should suddenly find that the half-life of every atom of U-238 at the surface of the Earth has been reduced from 4.5 billion years to something like 1 second! On this basis, any abrupt lowering of Earth potential by a mere million volts could be expected to produce rampant radioactivity, with consequent lethal or at least strongly mutational effects on all forms of life.
But of course we are probably unjustified in assuming that Figure 1 is applicable to the postulated conditions; it may well be that changing Earth potentials also shift the curve of Figure 1 up or down, right or left, so that changes in half-lives are much less drastic than that just described. And it may be, too, that nuclear binding forces are not entirely insensitive to environmental electric potentials, and that the levels of escape tunnels also vary as datum levels change.
Nevertheless, it would seem that Earth potentials must be taken into account in theories of radioactive decay. And we may be forgiven for suggesting here that parentless polonium, sometime in the past when the Earth’s electric potential was higher than it is today, could well have been a radioactive element with a reasonably long half-life, such that it could survive periods of cooling and crystallization in once-molten rocks.
An immediate conclusion from these data is that radiometric dating is problematical.