# Nucleon transition time

1. ### gildomar

73
I know that the nucleus can be considered a bunch of particles that constantly transition between protons and neutrons due to exchange. Given that, is it meaningful to talk about the "average" time that a nucleon spends as either a proton or a neutron before switching to the other? Or is that a non sequitor?

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### Staff: Mentor

That does not make sense, but you can still give a rough typical timescale for processes in the nucleus, corresponding to ##\hbar## divided by the binding energy of a nucleon.

4. ### ChrisVer

I am not sure, but I learned during my undergrad that the neutron is stable in the nucleus because it transforms to proton with pions before having the time to beta decay.
HOWEVER here I learned this is nonsense of an explanation and I even got a red ticket for posting a source... and now that I think of it, it's really nonsense because- then - there would be no beta decays for any nucleus...

But in general the characteristic time for a neutron to proton transisition is supposed to be the characteristic time of nuclear interactions... you can find that "characteristic" time only by seeing how much does it take for a photon to pass through a nucleus (so how much fast is the fastest interaction within the nucleus). That's by taking:
$t_{ch} \propto \frac{1 fm}{c}$
where 1fm is around the radius of the nucleus...

5. ### gildomar

73
Yeah, sorry about that; it was late and I really misinterpreted something that I had read. I realized how backwards it was after I actually slept on the matter.