From: Ronald Wong (ronwong@inreach.com)
Date: Tue Oct 31 2000 - 17:05:34 PST
Message-Id: <l03102806b62518329bb8@[209.209.20.24]> Date: Tue, 31 Oct 2000 17:05:34 -0800 From: Ronald Wong <ronwong@inreach.com> Subject: re: beta decay
One of David Lauter's students posed the following question concerning beta
decay:
>Why in the heck does an electron fly out of a nucleus?, especially considering
>the newly acquired proton? The student thought that the newly produced
>electron
>would be attracted to its fellow product, the newly produced proton. So
>his question was, "Why don't the two stick together?"
We tend to think of the nucleus in terms of their atoms.The atoms that we
are usually thinking of are stable ones. The result is that we think of the
nuclei as a stable, long-lived kind of object.
The fact is that the nucleus of an atom is a very dynamic sort of thing in
which a lot is going on.
For some atoms, the nucleus is even unstable. This is especially true for
the atom of elements with high atomic numbers (82 and above comes to mind).
The binding energy needed to hold the thriving mass of positively charged
protons together is constantly on the verge of losing the struggle to keep
things together despite the buffering action of the neutrons.
With time, failures arise in their own random way leading to a loss of
nuclear material and a return to a more stable condition (one which may
still be subject to change).
What needs to get emitted to bring about this stable condition varies.
Sometimes radiant energy in the form of gamma rays is all that it takes;
sometimes something more massive like the nucleus of a helium atom is
called for (the alpha particle); sometimes just an electron and it's
attendant neutrino is all that is necessary. Determining what and why takes
a background in quantum mechanics/physics.
So, while your student justifiably focused on the attraction between two
unlike charges in phrasing his/her question, the fact is that a totally
different kind of physics is at work - One that is modern in terms of it's
underlying principles but, at the same time old in terms of its overall
explanation. The beta decay is simply nature's way of changing from one
level of equilibrium to another. Sort of like the glass of water that falls
over when someone runs into the table. But, instead of the rush of water
and the sound made by the falling glass, we get the emission of an electron
and it's associated neutrino accompanied by the appearance of a proton in
the atom's nucleus.
Nuclear physics in the Fall. How times have changed. Could this be one of
television's legacies?
ron
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