Samarium-159

Properties and data of the isotope ¹⁵⁹Sm.

Content

General data

Name of the isotope:Samarium-159; Sm-159Symbol:¹⁵⁹Sm or 15962SmMass number A:159 (= number of nucleons)Atomic number Z:62 (= number of protons)Neutrons N:97Isotopic mass:158.933217(6) u (atomic weight of Samarium-159)Nuclide mass:158.8992077 u (calculated nuclear mass without electrons)Mass excess:-62.20796 MeVMass defect:1.392431836 u (per nucleus)Nuclear binding energy:1297.04190064 MeV (per nucleus)
8.15749623 MeV (average binding energy per nucleon)Separation energy:S_N = 5.029(8) MeV (first neutron)
S_P = 10.408(15) MeV (first proton)Half-life:11.37(15) sDecay constant λ:0.060962812714155 s^-1Specific activity α:2.323586363180 × 10⁺²⁰ Bq g^-1
6279963143.7322 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2-Year of discovery:1986

Radioactive Decay

Half-life T_½ = 11.37(15) s respectively 1.137 × 10¹ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁵⁹Eu	100 %	3.836(7) MeV

Parent Nuclides

Direct parent isotope is: ¹⁵⁹Pm.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 97) and isobaric (same nucleon number A = 159) with Samarium-159. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 97	Isobar A = 159
56	¹⁵³Ba
57	¹⁵⁴La
58	¹⁵⁵Ce
59	¹⁵⁶Pr	¹⁵⁹Pr
60	¹⁵⁷Nd	¹⁵⁹Nd
61	¹⁵⁸Pm	¹⁵⁹Pm
62	¹⁵⁹Sm	¹⁵⁹Sm
63	¹⁶⁰Eu	¹⁵⁹Eu
64	¹⁶¹Gd	¹⁵⁹Gd
65	¹⁶²Tb	¹⁵⁹Tb
66	¹⁶³Dy	¹⁵⁹Dy
67	¹⁶⁴Ho	¹⁵⁹Ho
68	¹⁶⁵Er	¹⁵⁹Er
69	¹⁶⁶Tm	¹⁵⁹Tm
70	¹⁶⁷Yb	¹⁵⁹Yb
71	¹⁶⁸Lu	¹⁵⁹Lu
72	¹⁶⁹Hf	¹⁵⁹Hf
73	¹⁷⁰Ta	¹⁵⁹Ta
74	¹⁷¹W	¹⁵⁹W
75	¹⁷²Re	¹⁵⁹Re
76	¹⁷³Os
77	¹⁷⁴Ir
78	¹⁷⁵Pt
79	¹⁷⁶Au
80	¹⁷⁷Hg
81	¹⁷⁸Tl
82	¹⁷⁹Pb