Talk:Even and odd atomic nuclei

Pairing effects
The primordial nuclide total listed here (289) does not match that given elsewhere in wikipedia i.e. at Primordial Nuclide (288). The EE value there is 169. I think that U-234 was accidently included here. The next long lived nuclide after Pu-244 (82My) is Nb-92 (37My). This should be the 289th primordial nuclide. U-235 has only a 245ky half life. The tables at the start and end of the article also need fixed to show 288 total primordial nuclides. 99.32.172.114 (talk) 05:23, 14 April 2013 (UTC)

Fissile nuclides
Fissile nuclides tend to have even Z and odd N. This is very important and should perhaps be more prominently stated in the article. Looking for better sources. Andrewa (talk) 04:07, 6 February 2024 (UTC)
 * https://www.researchgate.net/publication/253845692_Statistical_Approaches_to_the_Even-odd_Effect_in_Fission
 * https://www.sciencedirect.com/topics/earth-and-planetary-sciences/nuclear-binding-energy
 * https://link.springer.com/article/10.1134/S1063778823010222
 * I believe that they can also have odd Z, but those tend to have shorter half-life. But yes, odd N, and the article should explain that. It is the extra binding energy of paired neutrons that does it. Gah4 (talk) 06:42, 6 February 2024 (UTC)
 * Interesting... what would be an example of a fissile nuclide with odd Z? Andrewa (talk) 07:15, 6 February 2024 (UTC)
 * It appears that the odd-odd neptunium-236 is fissile, and not only fissionable. See page 13 of . Complex / Rational  18:35, 6 February 2024 (UTC)
 * Interesting... that's the source given here too. That document doesn't seem to cite the source of its information, and the document as a whole is a very deliberately conservative evaluation. Can we do better, I wonder? Andrewa (talk) 19:46, 12 February 2024 (UTC)
 * I found some more about it (and fissile nuclides in general) in – the key takeaway is that 236Np is fissile, but so difficult to produce that its critical mass has not been experimentally measured. It also clearly states that even-N nuclides such as 237Np and 241Am are not fissile, despite other sources categorizing them as such. I can email you a pdf of the article if you can't access it online.  Complex / Rational  23:44, 12 February 2024 (UTC)
 * I found some more about it (and fissile nuclides in general) in – the key takeaway is that 236Np is fissile, but so difficult to produce that its critical mass has not been experimentally measured. It also clearly states that even-N nuclides such as 237Np and 241Am are not fissile, despite other sources categorizing them as such. I can email you a pdf of the article if you can't access it online.  Complex / Rational  23:44, 12 February 2024 (UTC)

Odd-odd nuclides that are very stable to beta decay and/or IT
For some odd-odd nuclides, beta decay and/or IT requires high spin change. For the following nuclides, a such decay process is at least 3 forbidden non-unique or 4 forbidden unique. The states are taken from:

https://www.nndc.bnl.gov/nudat3/getdataset.jsp?nucleus=X&unc=NDS, where X is a nuclide symbol (for example https://www.nndc.bnl.gov/nudat3/getdataset.jsp?nucleus=50V&unc=NDS);

If the link does not work, an alternative is

https://www.nndc.bnl.gov/ensnds/M/X/adopted.pdf, where X is an element name and M is a mass number (for example https://www.nndc.bnl.gov/ensnds/50/V/adopted.pdf).

Beta decays of odd-odd nuclides with low spin change that take a long time to happen
Look at the level diagram (in keV) of some decay products: These levels are separated by $$2\hbar$$ units of spin, and their energies get further apart as the spin increases. That's a classic sign of collective nuclear rotation, with a rigid rotor having kinetic energy $$E\propto J^2$$. On the other hand, the high spins of 176Lu, 236Np, and 248Bk are intrinsic, so the decay processes must overcome a terrible match even if the spin change is low. Their β decay information: On the other hand, the longevity is probably not applicable to the unknown decay processes 212mAt → 212Po (9− → 8+, QEC = 271.84 keV) and 216mAt → 216Rn (9− → 8+, Qβ− = 517.68 keV), because the high spin of 212Po and 216Rn does not seem to be a result of collective nuclear rotation, as their level diagrams are irregular: It should be pointed out that, although not specified, it seems that 212mBi → 212Po (9− → 8+, Qβ− = 775.11 keV) is known, as shown in the last diagram of here. 129.104.241.193 (talk) 15:10, 7 May 2024 (UTC)