Talk:Isotopes of samarium#Samarium-146

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Since nuclear fuel is used for several years (burnup) in a nuclear power plant, the final amount of 151Sm in the spent nuclear fuel at discharge is only a small fraction of the total 151Sm produced during the use of the fuel.

This does not make any sense to me, and I strongly suspect it's wrong. With nearly 100 years half life only a few percent of 151Sm decays in the few years it sits in the reactor, so almost all should be present at discharge. --Feldkurat Katz (talk) 17:18, 16 May 2017 (UTC)

:You are correct that most of the Sm-151 does not decay during that time. However, this is not the primary means of depletion. While the Sm-151 remains inside the reactor, it is exposed to neutron radiation from the ongoing fission; as described in the previous paragraph to the sentence you quoted, Sm-151 absorbs neutrons and is transmuted into stable Sm-152. Thus, its concentration in spent fuel is lower than one would naïvely expect. Magic9mushroom (talk) 09:05, 6 August 2017 (UTC)

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The list at isotopes of promethium and all other sources I can find says that Promethium-147 decays to Samarium-147 by emitting a beta particle. The mass of Promethium-147 is 146.9151385 amu the mass of Samarium-147 is 146.9148979 amu. The difference between the two masses is 0.0002406 amu. A beta particle is nothing other than an electron, which has a rest mass of 5.48579909070×10−4 amu or 0.000548579909070 amu. That means the mass of the electron is greater than the mass difference between the two nuclei. This is impossible, isn't it? If the difference in masses were greater than the mass of the electron, that could be explained by it being carried away in the kinetic energy of the electron or in gamma rays. But you cannot gain mass without consuming energy. And where is this energy coming from? There is about a half electron mass missing (notice that I cut off the "uncertainty" in the brackets in each case and the order of magnitude of the problem is well outside the claimed measurement error). So... How does Promethium-147 emit an electron, create Samarium-147 and in the end there's mass to spare? Where is the mistake? An electron capture reaction can of course produce a mass defect that is smaller than an electron mass, but it cannot ever produce a net mass gain. To gain mass, there must be energy coming from somewhere. Where? Hobbitschuster (talk) 14:59, 19 February 2022 (UTC) Hobbitschuster (talk) 15:01, 19 February 2022 (UTC)

:Responded at Talk:Isotopes of promethium. ComplexRational (talk) 15:53, 19 February 2022 (UTC)

::There are also several responses at Wikipedia_Talk:WikiProject_Physics PianoDan (talk) 16:35, 19 February 2022 (UTC)

• Preliminary List of Main Isotopes: CR-list (Jan 2023)

:For Sm: stable: 144, 147, 148, 149, 150, 152, 154; other: 153, 151, 146 (144, 146–154 = 10)

• from {{tl|NUBASE2020}} (edit: c/p, replaced unk chars)

144Sm -81965.6 1.5 STABLE 0+ 01 1933 IS=3.08 4;2b+ ?
146Sm -80996 3 68 My7 0+ 16 1953 a=100
147Sm -79266.0 1.3 106.6 Gy0.5 7/2- * 09 FGK204 T 1933 IS=15.00 14; a=100
148Sm -79336.1 1.2 6.3 Py 1.3 0+ 14 16Ca43 T 1933 IS=11.25 9; a=100
149Sm -77135.9 1.2 STABLE >2Py 7/2- * 04 1933 IS=13.82 10; a ?
150Sm -77051.3 1.1 STABLE 0+ 13 1934 IS=7.37 9
151Sm -74576.5 1.1 94:6 y 0.6 5/2- * 09 15Be23 T 1947 b-=100
152Sm -74763.0 1.0 STABLE 0+ 13 1933 IS=26.74 9
153Sm -72560.1 1.0 46:2846 h 0.0023 3/2+ * 20 FGK209 T 1938 b-=100
154Sm -72455.6 1.3 STABLE >2.3Ey 0+ 09 1933 IS=22.74 14; 2b- ?

DePiep (talk) 05:11, 11 April 2023 (UTC)

• To be fixed: "source retracted" [https://en.wikipedia.org/w/index.php?title=Isotopes_of_samarium&diff=prev&oldid=1149270469&diffmode=source]: 146-Sm: "ref retracted": incomprehensible inline, reason=(1) "above" is unclear, (2) does not lead to ref source, (3) Needs: source to be used then.

:So: which source to be used?, and: which source was retracted, & how to note that one?

:-DePiep (talk) 05:35, 11 April 2023 (UTC)

:: {{ping|DePiep}} The relevant sentence is:

:::A 2012 paper revising the estimated half-life of ¹⁴⁶Sm from 10.3(5)×10⁷ y to 6.8(7)×10⁷ y was retracted in 2023.

:: This is followed by two inline references, one to the 2012 paper and the other to the 2023 retraction. jnestorius^(talk) 10:51, 11 April 2023 (UTC)

:::I could find that by researching, all right. However, any reader should arrive at the right ref right away (not "... above"). Also, still don't see what ia the source to be used is. DePiep (talk) 11:04, 11 April 2023 (UTC)

:::: the reference-tag contains a link that the reader is supposed to click on. I've expanded the link to include the word "above" if that's any clearer. jnestorius^(talk) 13:52, 11 April 2023 (UTC)

According to the trend shown in [https://arxiv.org/pdf/1908.11458.pdf], ¹⁴⁵Sm (N = 83) and ¹⁵¹Sm (N = 89) should have partial alpha-decay half-lives at the order of 10⁴⁷ years. Note the similar alpha decay energies: 1.12 MeV for the former and 1.15 MeV for the latter.

¹⁴³Sm (N = 81) has an extremely low alpha decay energy of 0.04 MeV, so alpha decay may be possible but with a half-life long beyond imagination. 129.104.241.214 (talk) 23:33, 24 October 2023 (UTC)

¹⁴⁶Sm is the only non-primordial even-even beta-stable nuclide with Z ≤ 83 that has lower energy than its beta-stable nominal double EC product. It is close to not be: the energy difference between ¹⁴⁶Nd and ¹⁴⁶Sm is small. 129.104.241.162 (talk) 04:10, 12 March 2024 (UTC)

Cristiano Toàn (talk) 02:13, 10 July 2024 (UTC) ¹⁴⁶Sm should be considered as trace nuclide rather. With earth's age is 4.54 billions years, with ¹⁴⁶Sm's half-life is 103 million years thus since the formation of earth. ¹⁴⁶Sm has undergone 44 half-lives and declined by factor of about 17. 59 trillion years. If we had 1 mole of ¹⁴⁶Sm when the earth was formed, We would still have about 34 billion ¹⁴⁶Sm's atoms survived today

:According to [https://www.sciencedirect.com/science/article/abs/pii/0012821X73901751 this article], the abundance of ¹⁴⁶Sm would be around 3.08% * 0.39 * 2^-43/1.03 = 3.25*10^-13%, corresponding to 1.96*10⁹ atoms per mole of Sm. This is really a tiny fraction: it takes only 4.38 hours for such an amount of ¹⁴³Nd to form with pure ¹⁴⁷Sm initially given! 14.52.231.91 (talk) 00:38, 16 August 2024 (UTC)

:The problem of ^146,147Sm is that they have too small atomic number. Hf, W, Os, and Pt each have primordial isotopes with Q_α-values exceeding 2.5 MeV, but such Q_α-values for around Z = 80 would almost be ignorable (see [https://arxiv.org/abs/1908.11458 here]). 14.52.231.91 (talk) 00:32, 26 August 2024 (UTC)

::And considering that ¹⁴⁸Gd and ¹⁹⁰Pt both have a Q_α-value of 3.27 MeV... (poor ¹⁴⁸Gd) 14.52.231.91 (talk) 00:15, 28 August 2024 (UTC)

There are chances that double EC of ¹⁴⁴Sm, α of ¹⁴⁹Sm, and double β^- of ¹⁵⁴Sm be observed; this would make Sm to have only two observationally stable isotopes (150 and 152) and five natually occurred ratioisotopes. Hf could enjoy a similar situation, as α of ^176,177,178Hf may be observed given the predictions [https://arxiv.org/abs/1908.11458 here], leaving only two observationally stable isotopes 179 and 180. 129.104.241.193 (talk) 23:08, 28 April 2024 (UTC)

Cristiano Toàn (talk) 01:12, 15 June 2024 (UTC) The problem to measure ¹⁴⁹Sm's half-life is its decay product ¹⁴⁵Nd is also energically allowed to undergo alpha decay and the latter predicted half-life is not so large to the former one

:By the way, ¹⁵²Sm is the only isotope whose main decay mode would be cluster decay; see [https://en.wikipedia.org/wiki/Talk:Cluster_decay#Theoretical_calculation_of_cluster_decays_for_mass_numbers_152-165,_201-205 here]. 14.52.231.91 (talk) 04:06, 29 August 2024 (UTC)

:Using the model [https://en.wikipedia.org/wiki/Talk:Alpha_decay#Formula_for_alpha_decays here], the alpha half-life of ¹⁴⁹Sm (Q_α = 1.871 MeV) would be around 3.8 × 10¹⁹ years. 2A04:CEC0:1929:32CB:7020:3AAB:EBF6:19C4 (talk) 16:14, 18 April 2025 (UTC)

:Double EC half-life of ¹⁴⁴Sm and double β^- half-life of ¹⁵⁴Sm may be [https://www.sciencedirect.com/science/article/pii/S0375947423000313 at the order of 10²¹ years], which is short than the theoretical alpha half-life of ¹⁴⁵Nd. 129.104.244.68 (talk) 19:12, 9 May 2025 (UTC)

class="wikitable" style="text-align:center"
Isotopes	Alpha decay energy (keV)	Note
129Sm	2940
130Sm	2885
131Sm	2801
132Sm	2512
133Sm	2680
134Sm	2661
135Sm	2484
136Sm	2191
137Sm	1879
138Sm	1724
139Sm	1409
140Sm	1319
141Sm	1216
142Sm	601
143Sm	44
144Sm	-144	Beta-stable with 82 neutrons
145Sm	1115
146Sm	2528	Beta-stable with 84 neutrons; least-energy isobar of A = 146
147Sm	2310	Beta-stable with 85 neutrons; least-energy isobar of A = 147
148Sm	1986	Beta-stable with 86 neutrons; least-energy isobar of A = 148
149Sm	1870	Beta-stable with 87 neutrons; least-energy isobar of A = 149
150Sm	1449	Beta-stable with 88 neutrons; least-energy isobar of A = 150
151Sm	1145
152Sm	220	Beta-stable with 90 neutrons; least-energy isobar of A = 152
153Sm	-610
154Sm	-1197	Beta-stable with 92 neutrons
155Sm	-1669
156Sm	-1637
157Sm	-1808
158Sm	-1950
159Sm	-2164
160Sm	-2313
161Sm	-2611
162Sm	-2779
163Sm	-3105
164Sm	-3179
165Sm	-3263

129.104.241.231 (talk) 14:49, 1 October 2024 (UTC)

See [https://phys.org/news/2024-08-uniquely-precise-life-samarium.html here]. 129.104.65.7 (talk) 07:59, 9 October 2024 (UTC)

:And [https://physicsworld.com/a/half-life-measurement-of-samarium-146-could-help-reveal-secrets-of-the-early-solar-system/ this one also] :) 2A04:CEC0:C015:E728:FD48:30B7:6D36:814A (talk) 23:15, 16 October 2024 (UTC)