How is beta-plus decay possible?

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Offline lunar11

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How is beta-plus decay possible?
« on: 09/03/2013 22:28:04 »
The proton has a half-life of about 10 to the power of 30 seconds. Then how is it that a proton decays to form a neutron, positron and an electron-neutrino aka beta-plus decay?

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Online evan_au

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Re: How is beta-plus decay possible?
« Reply #1 on: 10/03/2013 01:38:58 »
It's got to do with the lowest energy state.
A single, isolated proton (perhaps in a Hydrogen nucleus) is very stable. It takes more energy to break into other things. Hence the minimum estimated lifetime of 1032 seconds.  (See http://en.wikipedia.org/wiki/Proton_decay#Experimental_evidence)

However, when a proton is in the nucleus of an atom which has "too many" protons, the electrostatic repulsion of the protons imposes considerable stress on the nucleus, which is almost balanced by the attractive strong nuclear force from the protons and neutrons. It is a lower energy state to have 1 less proton, and 1 more neutron, hence this decay is energetically favourable.

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Offline lunar11

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Re: How is beta-plus decay possible?
« Reply #2 on: 11/03/2013 20:43:26 »
Thanks