Talk:Isotopes of fermium

Mendelevium

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Theoretically, is there an isotope of Fermium that decays into Mendelevium? So far, by extending the rn-process, I have gotten this far, but none decay into Mendelevium. Could maybe an extremely neutron-rich isotope decay into Mendelevium, and if so, what is it/could it be? 32ieww (talk) 19:44, 11 February 2017 (UTC)

The discussion above is closed. Please do not modify it. Subsequent comments should be made on the appropriate discussion page. No further edits should be made to this discussion.

It's not that unlikely. Probably a lot would. The problem is that they're all probably heavier than 260, so there'd be no way to reach them at present. Or rather, there is a way, but it's banned by treaty. :) Double sharp (talk) 15:15, 8 May 2024 (UTC)

Actually, we tried nuclear explosions in the 1960s and failed to get anything heavier than 257. The attempt was abandoned well before underground testing ceased in the US. In any case, the issue is not whether isotopes of Fm could beta-decay but whether they would do so, faster than SF, to a reasonably stable isotope, about which we have no certainty. 73.228.195.198 (talk) 15:19, 13 July 2025 (UTC)

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Spontaneous fission of ²⁴²Fm

Should it be noted that ²⁴²Fm is the lightest known nuclide to undergo purely spontaneous fission? 129.104.241.214 (talk) 01:57, 23 October 2023 (UTC)

Perhaps ²⁵⁷Fm is the last beta-stable nuclide whose SF branch is not significant

After all, the only known heavier beta-stable nuclides are ²⁵⁸Fm, ²⁶⁰Fm, ²⁵⁹Md, ²⁶⁰No and ²⁶²No, for all of which the only known decay mode is SF. 129.104.241.214 (talk) 11:35, 28 November 2023 (UTC)

Theoretical alpha half-life of ^258,259Fm

See here for ²⁵⁸Fm, and likewise for ²⁵⁹Fm. Alpha decays for both isotopes are predicted to be very insignificant (alpha partial half-lives similar to longer than that of the most stable isotope of fermium ²⁵⁷Fm). 129.104.241.242 (talk) 03:36, 5 May 2024 (UTC)

²⁶⁰Fm

NUBASE2020 says, in a footnote for ²⁶⁰Fm, "T1/2~4 ms and %SF=100 mode were reported in the 92Lo.B, but the results were not confirmed in the subsequent experiment by same group (97Lo.A)" (page 173). In the main table, the isotope is listed as EU (existence under discussion) and given an estimated half-life of 1 minute.

Shouldn't this mean this isotope page should list the 4 ms half-life and continue to list the isotope as unconfirmed? Or perhaps it shouldn't list the isotope at all? I haven't done anything to it because I'm not sure if it's fine the way it currently is, but I am putting this notice here on the talk page. Copernicium291 (talk) 15:38, 25 June 2025 (UTC)

I can't find the primary sources, and could not make a firm recommendation until I have seen them, but it seems any change would preferably to remove the isotope altogether, not having been reliably observed. Nubase's policy to list them with extrapolated data is not helpful, at least for half-life (there's no reason to doubt SF would be the observed decay mode). Your proposal is not unreasonable if we need not accept their judgement in all cases. 73.228.195.198 (talk) 15:00, 13 July 2025 (UTC)