Samarium-146

Properties and data of the isotope ¹⁴⁶Sm.

Content

General data

Name of the isotope:Samarium-146; Sm-146Symbol:¹⁴⁶Sm or 14662SmMass number A:146 (= number of nucleons)Atomic number Z:62 (= number of protons)Neutrons N:84Isotopic mass:145.913047(3) u (atomic weight of Samarium-146)Nuclide mass:145.8790377 u (calculated nuclear mass without electrons)Mass excess:-80.9962 MeVMass defect:1.299957928 u (per nucleus)Nuclear binding energy:1210.90301018 MeV (per nucleus)
8.29385623 MeV (average binding energy per nucleon)Separation energy:S_N = 8.4163(28) MeV (first neutron)
S_P = 7.018(4) MeV (first proton)Half-life:6.8(7) × 10⁷ aDecay constant λ:3.232287192601 × 10^-16 s^-1Specific activity α:1342433.7085251 Bq g^-1
3.6281992122 × 10^-5 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:4.9808(35) femtometer fmYear of discovery:1953

Radioactive Decay

Half-life T_½ = 6.8(7) × 10⁷ a respectively 2.144448 × 10¹⁵ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
α	¹⁴²Nd	100 %	2.5288(28) MeV

Parent Nuclides

Direct parent isotopes are: ¹⁴⁶Eu, ¹⁴⁶Pm, ¹⁵⁰Gd.

Occurrence

Comparison of the natural Samarium isotopes including isotopic abundance (mole fraction of the isotope mixture in percent):

	Atomic Mass m_a	Quantity	Half-life	Spin
Samarium Isotopic mixture	150.36 u	100 %
Isotope ¹⁴⁴Sm	143.91201(2) u	3.08(4) %	stable	0+
Isotope ¹⁴⁶Sm	145.913047(3) u	[trace]	6.8(7) × 10⁷ a	0+
Isotope ¹⁴⁸Sm	147.91483(2) u	11.25(9) %	7(3)×10¹⁵ a	0+
Isotope ¹⁴⁹Sm	148.91719(2) u	13.82(10) %	stable	7/2-
Isotope ¹⁵⁰Sm	149.91728(2) u	7.37(9) %	stable	0+
Isotope ¹⁵²Sm	151.91974(2) u	26.74(9) %	stable	0+
Isotope ¹⁵⁴Sm	153.92222(2) u	22.74(14) %	stable	0+
Isotope ¹⁴⁷Sm	146.91490(2) u	15.00(14) %	1.0625(38) × 10¹¹ a	7/2-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 84) and isobaric (same nucleon number A = 146) with Samarium-146. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 84	Isobar A = 146
47	¹³¹Ag
48	¹³²Cd
49	¹³³In
50	¹³⁴Sn
51	¹³⁵Sb
52	¹³⁶Te
53	¹³⁷I
54	¹³⁸Xe	¹⁴⁶Xe
55	¹³⁹Cs	¹⁴⁶Cs
56	¹⁴⁰Ba	¹⁴⁶Ba
57	¹⁴¹La	¹⁴⁶La
58	¹⁴²Ce	¹⁴⁶Ce
59	¹⁴³Pr	¹⁴⁶Pr
60	¹⁴⁴Nd	¹⁴⁶Nd
61	¹⁴⁵Pm	¹⁴⁶Pm
62	¹⁴⁶Sm	¹⁴⁶Sm
63	¹⁴⁷Eu	¹⁴⁶Eu
64	¹⁴⁸Gd	¹⁴⁶Gd
65	¹⁴⁹Tb	¹⁴⁶Tb
66	¹⁵⁰Dy	¹⁴⁶Dy
67	¹⁵¹Ho	¹⁴⁶Ho
68	¹⁵²Er	¹⁴⁶Er
69	¹⁵³Tm	¹⁴⁶Tm
70	¹⁵⁴Yb
71	¹⁵⁵Lu
72	¹⁵⁶Hf
73	¹⁵⁷Ta
74	¹⁵⁸W
75	¹⁵⁹Re