# Calculation of Isotop lifetimes

1. Aug 26, 2010

### Dmitry67

I know that Bismuth is not stable, Bi209 has a lifetime of 19*10^18y.
I also know that before decay was experimentally confirmed, it had been theoretically predicted.

My question is - HOW?

Is color chromodynamics advanced enough so it can calculate for any number of neutrons and protons the lifetime of the nuclei? Bi-209 contains more then 6 hundreds quarks - is it really possible to calculate a system with that many 'particles' just based on the QM equations?

Or may be, as there are so many particles, artificial models (droplet, shells) are used? But this is really strange: energy margin between Bi-209 being stable and having lifetime of 10^19y is so tiny that these ad-hoc models must be fastastically accurate!

Last edited: Aug 26, 2010
2. Aug 26, 2010

### DrDu

Wismut 209 is heavier than an He 4 and Tl 205,
hence it is unstable with respect to alpha decay.
see
http://dx.doi.org/10.1038%2Fnature01541 [Broken]

Last edited by a moderator: May 4, 2017
3. Aug 26, 2010

### Dmitry67

Thank you.
But could you comment on 2 approaches I menationed in my first post.
What is a precision of both methods right now?

4. Sep 6, 2010

### cgk

I'm not aware of any quark-level calculations for real'' atomic nuclei. Handling something like Bi209 is a highly nontrivial many-body problem even when using empirical strong force potentials (say, based on the pion exchange formula and extensions of it).

That being said, I'm into quantum chemistry and only ever skimmed through some theoretical nuclear structure books. So I'd love to be proven wrong. I also seem to remember that one of the books I had checked out said that isotope lifetimes can currently not be calculated, but I think the book was from the 80s or early 90s, so that might have changed in the meantime.