Talk:Trace radioisotope

Which radioisotopes are listed as trace versus syn in element infoboxes is grossly inconsistent. e.g. Pm 147 is listed as trace while I129 and even Po 210 are listed as syn. I'm going to try to fix these according to the following rule -- The following count as trace radioisotopes:

1) Any U238 U235 or Th232 product listed in the wikipedia article on decay chains. 2) U238 fission products where cumulative yield% ( http://ie.lbl.gov/fission/238U.txt ) * t1/2 is greater than 5 years -- basically anything at least as abundant as Pm147. (i.e. Pm147 Sm151 Cs137 Sr90 Se79 Sn126 Pd107 Tc99 129I 93Zr 135Cs) 3) Cosmogenics: Use discretion (3H, 7Be, and the isotopes listed in http://www.physics.purdue.edu/primelab/introduction/cosmogenic_nuclides.html (10Be, C14, Al26, Cl36, Ca41 I129) all seem fine to me) 4) Primordial plutonium and heavy radionuclides created by neutron capture (At least U236 (see http://www.don-lindsay-archive.org/creation/isotope_list.html *) , Pu239, Pu244)

• if you don't believe the ref for 236U, I'd point out that given normal decay, U236 can be no more than 5 times rarer than Pu244, and given half-lives and (n, gamma) cross-sections (http://www.nndc.bnl.gov/nudat2/), it should be considerably more common than Pu239 due to neutron capture from U235Speciman00 (talk) 06:19, 28 August 2009 (UTC)

¹³⁵Cs, ¹³⁷Cs, and ²¹⁰At are all synthetic nuclides

But what about exceptions? Examples include:

¹³⁵Cs

Why

Caesium-135 is a fission product, and thus does not occur in nature. Also, the only naturally occuring isotope of ₅₅Cs is ¹³³Cs, and thus ¹³⁵Cs is a synthetic nuclide.

¹³⁷Cs

Why

See ¹³⁵Cs.

²¹⁰At

Why

²¹⁰At is not part of any decay chain of any primordial actinide (²³²Th, ²³⁵U, ²³⁸U) nor any of its decay products (²¹⁶Po, ²¹⁹Rn, ²²⁶Ra, etc.), and thus is a synthetic nuclide.