Talk:Isotopes of curium

External links modified
Hello fellow Wikipedians,

I have just modified 2 external links on Isotopes of curium. Please take a moment to review my edit. If you have any questions, or need the bot to ignore the links, or the page altogether, please visit this simple FaQ for additional information. I made the following changes:
 * Added archive https://web.archive.org/web/20080923135135/http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf to http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf
 * Added archive https://web.archive.org/web/20080923135135/http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf to http://www.nndc.bnl.gov/amdc/nubase/Nubase2003.pdf

When you have finished reviewing my changes, you may follow the instructions on the template below to fix any issues with the URLs.

Cheers.— InternetArchiveBot  (Report bug) 14:12, 15 April 2017 (UTC)

Possible β− decay of 247Cm
Should it be noted that 247Cm is theorized to undergo β− decay? Of course, the decay energy is very small (around 43.8 keV, lower than possible electron capture of 123Te). 129.104.241.214 (talk) 19:00, 3 November 2023 (UTC)
 * The slowness of this decay is actually quite an annoyance when it comes to investigating berkelium. A neat pathway to the longest-lived 247 isotope so cruelly taken from us, whereas curium already has so many long-lived ones. :) Double sharp (talk) 08:54, 6 May 2024 (UTC)
 * Well in theory, 247Cm can also decay to the 5/2− state of 247Bk with a Q value 13.40 keV, or to the 7/2+ state with a Q value of 2.47 keV. Due to their high spin change with relatively low Q value, I would expect the 9/2− → 3/2− (ΔJΔπ = 3+, 2 forbidden unique) to have a half-life at the order of 1019 years and the 9/2− → 5/2− (ΔJΔπ = 2+, 2 forbidden non-unique) to have a half-life at the order of 1018 years.
 * It seems quite strange that the 9/2− → 7/2+ (ΔJΔπ = 1−, 1 forbidden non-unique) transition of 247Cm has very long half-life. In comparison, the 3/2+ → 5/2− (ΔJΔπ = 1−) transition of 157Tb has a Q value of only 5.5 keV, yet its half-life is only about 6.5×104 years (see here)! 129.104.241.193 (talk) 15:36, 7 May 2024 (UTC)
 * Very strange indeed.
 * It is also kind of a pain that no known Fm isotope undergoes β−. Though in practice Fm itself is enough of a unicorn that it wouldn't help as much as one might wish. Still wishing for 254Es targets for superheavy experiments. :) Double sharp (talk) 15:13, 8 May 2024 (UTC)
 * In theory 261Fm and 263Fm are good candidates for beta emission (the odd neutron should hinder SF branching, which several RS state should be favored due to 264Fm being double the doubly-magic 132Sn), though I haven't read of any planned synthesis attempts for hitherto unknown heavier isotopes in this region. And to think it's been almost 30 years since 260Fm was originally reported... Complex / Rational  23:20, 8 May 2024 (UTC)
 * Hey why hasn't note of the possible β− decay been added yet 24.115.255.37 (talk) 22:54, 19 May 2024 (UTC)

Curium-244 should have abundance marked as "trace"
In isotopes of plutonium, it is noted that there is a small amount of natural plutonium-244 in the earth. Assuming there are 2.5x10^21 atoms of natural Pu-244 in the earth (10 grams), Pu-244 has a half life of 8x10^7 years (2.5x10^15 seconds), Cm-244 has a half-life of 18 years, and Pu-244 has a 1 in 7x10^11 chance of double beta decay to Cm-244, then the following are true:

1. ~10^6 Pu-244 atoms decay on average every second.

2. Thus, a Cm-244 atom will form every 7x10^5 seconds on average.

3. ~800 or so Cm-244 atoms will form over the course of one Cm-244 half-life

4. Thus, there are Cm-244 atoms on Earth, making curium the heaviest natural element. 24.115.255.37 (talk) 02:37, 21 April 2024 (UTC)


 * Note that a <7.3×10−9% indicates a decay mode not observed; only an upper limit of such events is known. 129.104.241.193 (talk) 20:57, 2 May 2024 (UTC)
 * Okay. 24.115.255.37 (talk) 02:02, 5 May 2024 (UTC)
 * It's quite likely that elements 95 and 96 exist in nature. 247Cm should be produced in r-process events and has a fighting chance to make it to Earth before it decays (it has the longest half-life of all transplutonium nuclides known), and its decay chain passes through 243Am (the longest-lived Am isotope). But we're not quite yet at the sensitivity needed to find primordial 244Pu, so good luck confirming this for now.
 * Further than that, I wouldn't expect more natural elements on Earth, because half-lives drop too quickly and a modern Oklo is impossible. It's plausible that elements up to about 110 are briefly formed in r-process events, but probably you wouldn't get to the end of row 7 before neutron capture results in fission. Beyond that, there's always whatever is going on in Przybylski's Star to create natural actinoids, though no one really knows what transactinoid spectra would be and thus what to look for. Double sharp (talk) 08:53, 6 May 2024 (UTC)

Spontaneous fission
Cm is perhaps the first element whose SF of its isotopes is non-ignorable (of course, that depends on what intensity is considered as ignorable): 248Cm and 250Cm has very significant SF branch. 129.104.241.193 (talk) 16:37, 6 May 2024 (UTC)

The isotope 252Cm
I am not sure if 252Cm is known, but NNDC still have some information about it. Its alpha half-life is calculated as in the order of a million years. 129.104.241.193 (talk) 16:58, 6 May 2024 (UTC)
 * But probably β− or SF is much faster. :) Double sharp (talk) 05:50, 7 May 2024 (UTC)
 * Of course! Ah I didn't mean to expect that 252Cm would be very stable (in case of any ambiguity). 129.104.241.193 (talk) 15:38, 7 May 2024 (UTC)

Possible beta decay of 247Cm and possible double beta decay of 248Cm
247Bk is beta stable which makes 247Cm not beta stable due to the Mattauch isobar rule, so add that beta decay of 247Cm is theorized. Also, both 248Cm and 248Cf are beta stable, so one of them has to double beta decay into the other with a long half life (likely 248Cm is the double beta decayer) 24.115.255.37 (talk) 22:51, 19 May 2024 (UTC)