How is the decay time of an atom measured?

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Offline PmbPhy

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How is the decay time of an atom measured?
« on: 26/07/2014 15:45:25 »
Hi folks,

I recall talking to someone about this but I can't recall who it was or in what thread it was. I'm hoping they'll post in this thread and let me know.

I think that they wanted to know something about how one determines the decay time of an atom. I was reading today and was reminded of the fact that George Gamow successfully applied quantum tunneling for the first time. He used it to predict the decay rate of atoms decaying by alpha decay by assuming that alpha decay occurs due to quantum tunneling. The problem is modeled as follows; the alpha particle is assumed to move in a potential function which is caused by the sum of the strong force potential (i.e. Yukawa potential) and the Coulomb potential. The potential function is approximated to have the value V(r) = -V0[/0] for r < r1 and V = k2Ze2/r for r > r1 and E < Vmax where m = Coulomb constant. The alpha particle carries a charge of 2e.

The alpha particle rattles around inside the nucleus practically force free. It repeatedly hits the barrier and rebounds. There is a finite chance that the alpha particle will tunnel through the barrier on each impact against the barrier. Quantum mechanics allows one to determine the wave function in this case and therefore the probabilities we're interested in. There's too much to get into in order to understand the terms in the result so I'll leave it at that. But that's the mechanism.
« Last Edit: 29/07/2014 08:06:45 by chris »