Isotopes of samarium

Short description: Nuclides with atomic number of 62 but with different mass numbers

Main isotopes of Chemistry:samarium (62Sm) | Iso­tope | Decay

|

| abun­dance | half-life (t1/2) | mode | pro­duct
144Sm  | 3.08%  | stable
145Sm  | syn | 340 d  | ε | 145Pm
146Sm  | syn  | 6.8×107 y  | α | 142Nd
147Sm  | 15.00%  | 1.06×1011 y  | α  | 143Nd
148Sm  | 11.25%  | 7×1015 y  | α  | 144Nd
149Sm  | 13.82%  | stable
150Sm  | 7.37%  | stable
151Sm  | syn  | 88.8 y  | β− | 151Eu
152Sm  | 26.74%  | stable
153Sm  | syn  | 46.284 h  | β− | 153Eu
154Sm  | 22.74%  | stable
Standard atomic weight Ar, standard(Sm)|

* 150.36(2)[1]

view * talk * edit

Naturally occurring samarium (62Sm) is composed of five stable isotopes, 144Sm, 149Sm, 150Sm, 152Sm and 154Sm, and two extremely long-lived radioisotopes, 147Sm (half life: 1.06×1011 y) and 148Sm (7×1015 y), with 152Sm being the most abundant (26.75% natural abundance). 146Sm is also fairly long-lived, but is not long-lived enough to have survived in significant quantities from the formation of the Solar System on Earth, although it remains useful in radiometric dating in the Solar System as an extinct radionuclide.[2][3] A 2012 paper revising the estimated half-life of 146Sm from 10.3(5)×107 y to 6.8(7)×107 y was retracted in 2023.[3][4] It is the longest-lived nuclide that has not yet been confirmed to be primordial.

Other than the naturally occurring isotopes, the longest-lived radioisotopes are 151Sm, which has a half-life of 88.8 years,[5] and 145Sm, which has a half-life of 340 days. All of the remaining radioisotopes, which range from 129Sm to 168Sm, have half-lives that are less than two days, and the majority of these have half-lives that are less than 48 seconds. This element also has twelve known isomers with the most stable being 141mSm (t1/2 22.6 minutes), 143m1Sm (t1/2 66 seconds) and 139mSm (t1/2 10.7 seconds).

The long lived isotopes, 146Sm, 147Sm, and 148Sm, primarily decay by alpha decay to isotopes of neodymium. Lighter unstable isotopes of samarium primarily decay by electron capture to isotopes of promethium, while heavier ones decay by beta decay to isotopes of europium.

Isotopes of samarium are used in samarium–neodymium dating for determining the age relationships of rocks and meteorites.

151Sm is a medium-lived fission product and acts as a neutron poison in the nuclear fuel cycle. The stable fission product 149Sm is also a neutron poison.

## Contents

* 1 List of isotopes
* 2 Samarium-149
* 3 Samarium-151
* 4 Samarium-153
* 5 References

## List of isotopes

Nuclide
[n 1] | Z | N | Isotopic mass (u)
[n 2][n 3] | Half-life
[n 4][n 5] | Decay
mode
[n 6] | Daughter
isotope
[n 7][n 8] | Spin and
parity
[n 9][n 5] | Physics:Natural abundance (mole fraction)

|
|
|
|
|
|
|
|

Excitation energy[n 5] | Normal proportion  | Range of variation
129Sm  | 62  | 67  | 128.95464(54)#  | 550(100) ms  |  |  | 5/2+#  |  |
130Sm  | 62  | 68  | 129.94892(43)#  | 1# s  | β+ | 130Pm  | 0+  |  |
131Sm  | 62  | 69  | 130.94611(32)#  | 1.2(2) s  | β+ | 131Pm  | 5/2+#  |  |
β+, p (rare)  | 130Nd
132Sm  | 62  | 70  | 131.94069(32)#  | 4.0(3) s  | β+ | 132Pm  | 0+  |  |
β+, p  | 131Nd
133Sm  | 62  | 71  | 132.93867(21)#  | 2.90(17) s  | β+ | 133Pm  | (5/2+)  |  |
β+, p  | 132Nd
134Sm  | 62  | 72  | 133.93397(21)#  | 10(1) s  | β+ | 134Pm  | 0+  |  |
135Sm  | 62  | 73  | 134.93252(17)  | 10.3(5) s  | β+ (99.98%)  | 135Pm  | (7/2+)  |  |
β+, p (.02%)  | 134Nd
135mSm  | 0(300)# keV  | 2.4(9) s  | β+ | 135Pm  | (3/2+, 5/2+)  |  |
136Sm  | 62  | 74  | 135.928276(13)  | 47(2) s  | β+ | 136Pm  | 0+  |  |
136mSm  | 2264.7(11) keV  | 15(1) μs  |  |  | (8−)  |  |
137Sm  | 62  | 75  | 136.92697(5)  | 45(1) s  | β+ | 137Pm  | (9/2−)  |  |
137mSm  | 180(50)# keV  | 20# s  | β+ | 137Pm  | 1/2+#  |  |
138Sm  | 62  | 76  | 137.923244(13)  | 3.1(2) min  | β+ | 138Pm  | 0+  |  |
139Sm  | 62  | 77  | 138.922297(12)  | 2.57(10) min  | β+ | 139Pm  | 1/2+  |  |
139mSm  | 457.40(22) keV  | 10.7(6) s  | IT (93.7%)  | 139Sm  | 11/2−  |  |
β+ (6.3%)  | 139Pm
140Sm  | 62  | 78  | 139.918995(13)  | 14.82(12) min  | β+ | 140Pm  | 0+  |  |
141Sm  | 62  | 79  | 140.918476(9)  | 10.2(2) min  | β+ | 141Pm  | 1/2+  |  |
141mSm  | 176.0(3) keV  | 22.6(2) min  | β+ (99.69%)  | 141Pm  | 11/2−  |  |
IT (.31%)  | 141Sm
142Sm  | 62  | 80  | 141.915198(6)  | 72.49(5) min  | β+ | 142Pm  | 0+  |  |
143Sm  | 62  | 81  | 142.914628(4)  | 8.75(8) min  | β+ | 143Pm  | 3/2+  |  |
143m1Sm  | 753.99(16) keV  | 66(2) s  | IT (99.76%)  | 143Sm  | 11/2−  |  |
β+ (.24%)  | 143Pm
143m2Sm  | 2793.8(13) keV  | 30(3) ms  |  |  | 23/2(−)  |  |
144Sm  | 62  | 82  | 143.911999(3)  | Stable[n 10] | 0+  | 0.0307(7)  |
144mSm  | 2323.60(8) keV  | 880(25) ns  |  |  | 6+  |  |
145Sm  | 62  | 83  | 144.913410(3)  | 340(3) d  | EC | 145Pm  | 7/2−  |  |
145mSm  | 8786.2(7) keV  | 990(170) ns
[0.96(+19−15) μs]  |  |  | (49/2+)  |  |
146Sm  | 62  | 84  | 145.913041(4)  | 1.03(5)×108 y[6] | α | 142Nd | 0+  | Trace  |
147Sm[n 11][n 12][n 13] | 62  | 85  | 146.9148979(26)  | (1.066±0.5)×1011 y | α  | 143Nd | 7/2−  | 0.1499(18)  |
148Sm[n 11] | 62  | 86  | 147.9148227(26)  | (6.3±1.3)×1015 y | α  | 144Nd | 0+  | 0.1124(10)  |
149Sm[n 12][n 14] | 62  | 87  | 148.9171847(26)  | Observationally stable[n 10] | 7/2−  | 0.1382(7)  |
150Sm  | 62  | 88  | 149.9172755(26)  | Stable[n 10] | 0+  | 0.0738(1)  |
151Sm[n 12][n 14] | 62  | 89  | 150.9199324(26)  | 94.6±0.6 y | β− | 151Eu | 5/2−  |  |
151mSm  | 261.13(4) keV  | 1.4(1) μs  |  |  | (11/2)−  |  |
152Sm[n 12] | 62  | 90  | 151.9197324(27)  | Stable[n 10] | 0+  | 0.2675(16)  |
153Sm[n 12] | 62  | 91  | 152.9220974(27)  | 46.2846±0.0023 h | β− | 153Eu | 3/2+  |  |
153mSm  | 98.37(10) keV  | 10.6(3) ms  | IT  | 153Sm  | 11/2−  |  |
154Sm[n 12] | 62  | 92  | 153.9222093(27)  | Observationally stable[n 10] | 0+  | 0.2275(29)  |
155Sm  | 62  | 93  | 154.9246402(28)  | 22.3(2) min  | β− | 155Eu  | 3/2−  |  |
156Sm  | 62  | 94  | 155.925528(10)  | 9.4(2) h  | β− | 156Eu  | 0+  |  |
156mSm  | 1397.55(9) keV  | 185(7) ns  |  |  | 5−  |  |
157Sm  | 62  | 95  | 156.92836(5)  | 8.03(7) min  | β− | 157Eu  | (3/2−)  |  |
158Sm  | 62  | 96  | 157.92999(8)  | 5.30(3) min  | β− | 158Eu  | 0+  |  |
159Sm  | 62  | 97  | 158.93321(11)  | 11.37(15) s  | β− | 159Eu  | 5/2−  |  |
160Sm  | 62  | 98  | 159.93514(21)#  | 9.6(3) s  | β− | 160Eu  | 0+  |  |
161Sm  | 62  | 99  | 160.93883(32)#  | 4.349+0.425
−0.441 s[7] | β− | 161Eu  | 7/2+#  |  |
162Sm  | 62  | 100  | 161.94122(54)#  | 3.369+0.200
−0.303 s[7] | β− | 162Eu  | 0+  |  |
163Sm  | 62  | 101  | 162.94536(75)#  | 1.744+0.180
−0.204 s[7] | β− | 163Eu  | 1/2−#  |  |
164Sm  | 62  | 102  | 163.94828(86)#  | 1.422+0.54
−0.59 s[7] | β− | 164Eu  | 0+  |  |
165Sm  | 62  | 103  | 164.95298(97)#  | 592+51
−55 ms[7] | β− (98.64%)  | 165Eu  | 5/2−#  |  |
β−, n (1.36%)  | 164Eu
166Sm  | 62  | 104  |  | 396+56
−63 ms[7] | β− (95.62%)  | 166Eu  | 0+  |  |
β−, n (4.38%)  | 165Eu
167Sm  | 62  | 105  |  | 334+83
−78 ms[7] | β− | 167Eu  |  |  |
β−, n  | 166Eu
168Sm  | 62  | 106  |  | 353+210
−164 ms[7] | β− | 168Eu  | 0+  |  |
β−, n  | 167Eu

1. ↑ mSm - Excited nuclear isomer.
2. ↑ ( ) - Uncertainty (1σ) is given in concise form in parentheses after the corresponding last digits.
3. ↑ # - Atomic mass marked #: value and uncertainty derived not from purely experimental data, but at least partly from trends from the Mass Surface (TMS).
4. ↑ Bold half-life - nearly stable, half-life longer than age of universe.
5. ↑ 5.0 5.1 5.2 # - Values marked # are not purely derived from experimental data, but at least partly from trends of neighboring nuclides (TNN).
6. ↑ Modes of decay:  IT: | Isomeric transition

|

p: | Proton emission
7. ↑ Bold italics symbol as daughter - Daughter product is nearly stable.
8. ↑ Bold symbol as daughter - Daughter product is stable.
9. ↑ ( ) spin value - Indicates spin with weak assignment arguments.
10. ↑ 10.0 10.1 10.2 10.3 10.4 Cite error: Invalid `<ref>` tag; no text was provided for refs named `{{{1}}}`
11. ↑ 11.0 11.1 Primordial radioisotope
12. ↑ 12.0 12.1 12.2 12.3 12.4 12.5 Fission product
13. ↑ Used in Samarium–neodymium dating
14. ↑ 14.0 14.1 Neutron poison in reactors

## Samarium-149

Samarium-149 (149Sm) is an observationally stable isotope of samarium (predicted to decay, but no decays have ever been observed, giving it a half-life at least several orders of magnitude longer than the age of the universe), and a product of the decay chain from the fission product 149Nd (yield 1.0888%). 149Sm is a neutron-absorbing nuclear poison with significant effect on nuclear reactor operation, second only to 135Xe. Its neutron cross section is 40140 barns for thermal neutrons.

The equilibrium concentration (and thus the poisoning effect) builds to an equilibrium value in about 500 hours (about 20 days) of reactor operation, and since 149Sm is stable, the concentration remains essentially constant during further reactor operation. This contrasts with xenon-135, which accumulates from the beta decay of iodine-135 (a short lived fission product) and has a high neutron cross section, but itself decays with a half-life of 9.2 hours (so does not remain in constant concentration long after the reactor shutdown), causing the so-called xenon pit.

## Samarium-151

Medium-lived
fission products Prop:
Unit:  | t½
(a)  | Yield
(%)  | Q *
(keV)  | βγ *

|
|
|
|

155Eu | 4.76  | 0.0803 | 252  | βγ
85Kr | 10.76  | 0.2180 | 687  | βγ
113mCd | 14.1  | 0.0008 | 316  | β
90Sr | 28.9  | 4.505  | 2826 | β
137Cs | 30.23  | 6.337  | 1176 | βγ
121mSn | 43.9  | 0.00005  | 390  | βγ
151Sm | 88.8  | 0.5314 | 77  | β
Yield, % per fission[8] | Thermal | Fast | 14 MeV

|
|
|

232Th | not fissile | 0.399 ± 0.065  | 0.165 ± 0.035
233U | 0.333 ± 0.017  | 0.312 ± 0.014  | 0.49 ± 0.11
235U | 0.4204 ± 0.0071  | 0.431 ± 0.015  | 0.388 ± 0.061
238U | not fissile | 0.810 ± 0.012  | 0.800 ± 0.057
239Pu | 0.776 ± 0.018  | 0.797 ± 0.037  | ?
241Pu | 0.86 ± 0.24  | 0.910 ± 0.025  | ?

Samarium-151 (151Sm) has a half-life of 88.8 years, undergoing low-energy beta decay, and has a fission product yield of 0.4203% for thermal neutrons and 235U, about 39% of 149Sm's yield. The yield is somewhat higher for 239Pu.

Its neutron absorption cross section for thermal neutrons is high at 15200 barns, about 38% of 149Sm's absorption cross section, or about 20 times that of 235U. Since the ratios between the production and absorption rates of 151Sm and 149Sm are almost equal, the two isotopes should reach similar equilibrium concentrations. Since 149Sm reaches equilibrium in about 500 hours (20 days), 151Sm should reach equilibrium in about 50 days.

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. According to one study, the mass fraction of 151Sm in spent fuel is about 0.0025 for heavy loading of MOX fuel and about half that for uranium fuel, which is roughly two orders of magnitude less than the mass fraction of about 0.15 for the medium-lived fission product 137Cs.[9] The decay energy of 151Sm is also about an order of magnitude less than that of 137Cs. The low yield, low survival rate, and low decay energy mean that 151Sm has insignificant nuclear waste impact compared to the two main medium-lived fission products 137Cs and 90Sr.

* ANL factsheet

## Samarium-153

Samarium-153 (153Sm) has a half-life of 46.3 hours, undergoing β− decay into 153Eu. As a component of samarium lexidronam, it is used in palliation of bone cancer.[10] It is treated by the body in a similar manner to calcium, and it localizes selectively to bone.

## References

* Isotope masses from:
* Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A 729: 3–128, doi:10.1016/j.nuclphysa.2003.11.001, Bibcode: 2003NuPhA.729....3A, https://hal.archives-ouvertes.fr/in2p3-00020241/document
* Isotopic compositions and standard atomic masses from:
* Wieser, Michael E. (2006). "Atomic weights of the elements 2005 (IUPAC Technical Report)". Pure and Applied Chemistry 78 (11): 2051–2066. doi:10.1351/pac200678112051.
* Half-life, spin, and isomer data selected from the following sources.
* Audi, Georges; Bersillon, Olivier; Blachot, Jean; Wapstra, Aaldert Hendrik (2003), "The NUBASE evaluation of nuclear and decay properties", Nuclear Physics A 729: 3–128, doi:10.1016/j.nuclphysa.2003.11.001, Bibcode: 2003NuPhA.729....3A, https://hal.archives-ouvertes.fr/in2p3-00020241/document
* National Nuclear Data Center. "NuDat 2.x database". Brookhaven National Laboratory. http://www.nndc.bnl.gov/nudat2/.
* Lide, David R., ed (2004). "11. Table of the Isotopes". CRC Handbook of Chemistry and Physics (85th ed.). Boca Raton, Florida: CRC Press. ISBN 978-0-8493-0485-9.

1. ↑ Meija, Juris; Coplen, Tyler B.; Berglund, Michael; Brand, Willi A.; De Bièvre, Paul; Gröning, Manfred; Holden, Norman E.; Irrgeher, Johanna et al. (2016). "Atomic weights of the elements 2013 (IUPAC Technical Report)". Pure and Applied Chemistry 88 (3): 265–91. doi:10.1515/pac-2015-0305.
2. ↑ Samir Maji et al. (2006). "Separation of samarium and neodymium: a prerequisite for getting signals from nuclear synthesis". Analyst 131 (12): 1332–1334. doi:10.1039/b608157f. PMID 17124541. Bibcode: 2006Ana...131.1332M.
3. ↑ 3.0 3.1 Kinoshita, N.; Paul, M.; Kashiv, Y.; Collon, P.; Deibel, C. M.; DiGiovine, B.; Greene, J. P.; Henderson, D. J. et al. (30 March 2012). "A Shorter 146Sm Half-Life Measured and Implications for 146Sm-142Nd Chronology in the Solar System" (in en). Science 335 (6076): 1614–1617. doi:10.1126/science.1215510. ISSN 0036-8075. PMID 22461609. Bibcode: 2012Sci...335.1614K.
4. ↑

* Kinoshita, N.; Paul, M.; Kashiv, Y.; Collon, P.; Deibel, C. M.; DiGiovine, B.; Greene, J. P.; Jiang, C. L. et al. (30 March 2023). "Retraction". Science 379 (6639): 1307. doi:10.1126/science.adh7739. PMID 36996231.
* Joelving, Frederik (30 March 2023). "One small error for a physicist, one giant blunder for planetary science". https://retractionwatch.com/2023/03/30/one-small-error-for-a-physicist-one-giant-blunder-for-planetary-science/.

5. ↑ He, M.; Shen, H.; Shi, G.; Yin, X.; Tian, W.; Jiang, S. (2009). "Half-life of 151Sm remeasured". Physical Review C 80 (6): 064305. doi:10.1103/PhysRevC.80.064305. Bibcode: 2009PhRvC..80f4305H.
6. ↑ See retraction note above
7. ↑ 7.0 7.1 7.2 7.3 7.4 7.5 7.6 7.7 Kiss, G. G.Expression error: Unrecognized word "et". (2022). "Measuring the β-decay properties of neutron-rich exotic Pm, Sm, Eu, and Gd isotopes to constrain the nucleosynthesis yields in the rare-earth region". The Astrophysical Journal 936 (107): 107. doi:10.3847/1538-4357/ac80fc. Bibcode: 2022ApJ...936..107K.
8. ↑ https://www-nds.iaea.org/sgnucdat/c3.htm Cumulative Fission Yields, IAEA
9. ↑ Christophe Demazière. ﻿Reactor Physics Calculations on MOX Fuel in Boiling Water Reactors (BWRs)﻿ (Report). OECD Nuclear Energy Agency. http://www.oecd-nea.org/pt/docs/iem/jeju02/session5/SectionV-12.pdf. Figure 2, page 6
10. ↑ Ballantyne, Jane C; Fishman, Scott M; Rathmell, James P. (2009-10-01). Bonica's Management of Pain. Lippincott Williams & Wilkins. pp. 655–. ISBN 978-0-7817-6827-6. https://books.google.com/books?id=Pms0hxH8f-sC&pg=PA655. Retrieved 19 July 2011.

* v
* t
* e

Isotopes of the chemical elements

| Group | 1 | 2 | 3 |  | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18

|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|

Period | Alkali metals  | Alkaline earth metals  |  |  |  |  |  |  |  |  |  |  |  |  |  | Pnicto­gens  | Chal­co­gens  | Halo­gens  | Noble gases
1 |

Iso's * List

1  |  |

Iso's * List

2 |

Iso's * List

3  |

Iso's * List

4  |  |

Iso's * List

5  |

Iso's * List

6  |

Iso's * List

7  |

Iso's * List

8  |

Iso's * List

9  |

Iso's * List

3 |

Iso's * List

11  |

Iso's * List

12  |  |

Iso's * List

13  |

Iso's * List

14  |

Iso's * List

15  |

Iso's * List

16  |

Iso's * List

17  |

Iso's * List

4 |

Iso's * List

19  |

Iso's * List

20  |

Iso's * List

21  |  |

Iso's * List

22  |

Iso's * List

23  |

Iso's * List

24  |

Iso's * List

25  |

Iso's * List

26  |

Iso's * List

27  |

Iso's * List

28  |

Iso's * List

29  |

Iso's * List

30  |

Iso's * List

31  |

Iso's * List

32  |

Iso's * List

33  |

Iso's * List

34  |

Iso's * List

35  |

Iso's * List

5 |

Iso's * List

37  |

Iso's * List

38  |

Iso's * List

39  |  |

Iso's * List

40  |

Iso's * List

41  |

Iso's * List

42  |

Iso's * List

43  |

Iso's * List

44  |

Iso's * List

45  |

Iso's * List

46  |

Iso's * List

47  |

Iso's * List

48  |

Iso's * List

49  |

Iso's * List

50  |

Iso's * List

51  |

Iso's * List

52  |

Iso's * List

53  |

Iso's * List

6 |

Iso's * List

55  |

Iso's * List

56  |

Iso's * List

57  |  |

Iso's * List

72  |

Iso's * List

73  |

Iso's * List

74  |

Iso's * List

75  |

Iso's * List

76  |

Iso's * List

77  |

Iso's * List

78  |

Iso's * List

79  |

Iso's * List

80  |

Iso's * List

81  |

Iso's * List

82  |

Iso's * List

83  |

Iso's * List

84  |

Iso's * List

85  |

Iso's * List

7 |

Iso's * List

87  |

Iso's * List

88  |

Iso's * List

89  |  |

Iso's * List

104  |

Iso's * List

105  |

Iso's * List

106  |

Iso's * List

107  |

Iso's * List

108  |

Iso's * List

109  |

Iso's * List

110  |

Iso's * List

111  |

Iso's * List

112  |

Iso's * List

113  |

Iso's * List

114  |

Iso's * List

115  |

Iso's * List

116  |

Iso's * List

117  |

Iso's * List

118
|  |  |  |  |

Iso's * List

58  |

Iso's * List

59  |

Iso's * List

60  |

Iso's * List

61  |

Iso's * List

62  |

Iso's * List

63  |

Iso's * List

64  |

Iso's * List

65  |

Iso's * List

66  |

Iso's * List

67  |

Iso's * List

68  |

Iso's * List

69  |

Iso's * List

70  |

Iso's * List

71  |
|  |

Iso's * List

90  |

Iso's * List

91  |

Iso's * List

92  |

Iso's * List

93  |

Iso's * List

94  |

Iso's * List

95  |

Iso's * List

96  |

Iso's * List

97  |

Iso's * List

98  |

Iso's * List

99  |

Iso's * List

100  |

Iso's * List

101  |

Iso's * List

102  |

Iso's * List

103

* Table of nuclides
* Categories: Isotopes
* Tables of nuclides
* Metastable isotopes
* Isotopes by element

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/Isotopes of samarium. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Physics:Isotopes_of_samarium&oldid=2934586"
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template