🚀 go-pugleaf

In article <38C15B47.3D1C02AB@hotpop.com> 
Jeppe Stig Nielsen <jeppesn@hotpop.com> writes:
>
>Heavy nuclei are usually surrounded by a large number of orbital electrons.
>Some unstable, proton-rich nuclei primarily decay by capturing an orbital
>electron from the 1st shell (the K shell), like
>
>   p + e  ->  n + neutrino

 Correct.  Some of these also positron decay, but because that 
 decay mode requires an extra 1.022 MeV of mass difference compared
 to electron capture, there are nuclei that can only decay by EC.

>My question is this: If you strip away *all* electrons from such a nucleus,
>making K-capture impossible, how much may the life-time of the nucleus be
>increased (in percents)?

 If that nucleus cannot positron decay, it is now stable.  Its lifetime 
 is infinite (modulo the possiblity that a free proton will decay, which 
 has yet to be seen).  So the answer would be "infinite %".

>Are there table values for the life-times of these "isolated" nuclei? The
>usual tables are valid for nuclei in electrically neutral atoms only.

 The tables are enough, because you can use them to calculate the 
 lifetime.  If positron decay is possible, the measured beta+/EC 
 ratio can be used to calculate the lifetime if EC is made impossible. 

>[This posting is an approximate translation of a question in Danish from
><URL:news:dk.videnskab>.]

 An excellent translation.  I hope it does as well the other way.

-- 
 James A. Carr   <jac@scri.fsu.edu>     | Commercial e-mail is _NOT_ 
    http://www.scri.fsu.edu/~jac/       | desired to this or any address 
 Supercomputer Computations Res. Inst.  | that resolves to my account 
 Florida State, Tallahassee FL 32306    | for any reason at any time. 

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