How long do fundamental particles last?

25 November 2012


Cartoon schematic of an atom



Dear  Dr. Smith,

How long do protons and neutrons survive outside an atom?



Martin - Protons and electrons, as far as we're concerned in our lifetime last forever...

Neutrons last for just under 15 minutes if they're on their own.

To do an experiment - actually the experiments we do with neutron scattering take place where you only need for them to last for less than a second, so that's not an issue - but you can actually capture neutrons, and put them in something like a little bottle. They last for just under 15 minutes. If you have a neutron that's actually part of a nucleus, then it effectively lasts forever. But, on its own, just under 15 minutes.

Dave - So being inside that nucleus is somehow stabilising it, making it last a lifetime?

Martin - Yes, absolutely.


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