Talk:Isotopes of samarium

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Samarium-151
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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Where does Samarium-147 get "half an electron mass too much mass"?
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)

Main isotopes

 * 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)

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)
 * from NUBASE2020 (edit: c/p, replaced unk chars)

Samarium-146

 * To be fixed: "source retracted" : 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)
 * 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)

Possible alpha decay of 143Sm, 145Sm and 151Sm
According to the trend shown in, 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 stable to double EC
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

Most stable isotopes of Sm
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 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