Talk:Isotopes of curium

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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).

Comparison of the four odd-mass nuclides that are nearly beta-stable

Decay process	Qβ (keV)	Spin change	Half-life (a)
113Cd → 113In	320.34	1/2+ → 9/2+ (ΔJΔπ = 4+, 4 forbidden non-unique)	8.04×1015
115In → 115Sn	499.36	9/2+ → 1/2+ (ΔJΔπ = 4+, 4 forbidden non-unique)	4.41×1014
123Te → 123Sb	52.22	1/2+ → 7/2+ (ΔJΔπ = 3+, 2 forbidden unique)	(4.2−7.2)×1019 (predicted)
247Cm → 247Bk	43.8	9/2− → 3/2− (ΔJΔπ = 3+, 2 forbidden unique)	?

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. The former process is 2 forbidden non-unique and the latter is 1 forbidden non-unique.

Some well-known β decay processes with very small Q value include ¹⁶³Ho → ¹⁶³Dy (7/2⁻ → 5/2⁻, Q_EC = 2.555 keV), ¹⁸⁷Re → ¹⁸⁷Os (5/2⁺ → 1/2⁻, Q_β− = 2.469 keV), and ²⁴³Cm → ²⁴³Am (5/2⁺ → 5/2⁻, Q_β− = 7.48 keV). The three processes have respectively ΔJ^Δπ = 1⁺ (allowed), 2⁻ (1 forbidden unique), and 0⁻ (1 forbidden non-unique). It seems quite strange: Being 1 forbidden non-unique at the same time, ²⁴³Cm → ²⁴³Am has very short half-life, and ²⁴⁷Cm → ²⁴⁷Bk (9/2⁻ → 7/2⁺) has very long one! 129.104.241.193 (talk) 15:36, 7 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)