Samarium-161

Properties and data of the isotope ¹⁶¹Sm.

Content

General data

Name of the isotope:Samarium-161; Sm-161Symbol:¹⁶¹Sm or 16162SmMass number A:161 (= number of nucleons)Atomic number Z:62 (= number of protons)Neutrons N:99Isotopic mass:160.939160(7) u (atomic weight of Samarium-161)Nuclide mass:160.9051507 u (calculated nuclear mass without electrons)Mass excess:-56.67209 MeVMass defect:1.403818668 u (per nucleus)Nuclear binding energy:1307.64866633 MeV (per nucleus)
8.12204141 MeV (average binding energy per nucleon)Separation energy:S_N = 4.508(9) MeV (first neutron)
S_P = 10.96(20) MeV (first proton)Half-life:4.8(4) sDecay constant λ:0.14440566261666 s^-1Specific activity α:5.435195257812 × 10⁺²⁰ Bq g^-1
14689716913.007 Ci g^-1Spin and parity:
(nuclear angular momentum)(7/2+)Year of discovery:1998

Radioactive Decay

Half-life T_½ = 4.8(4) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁶¹Eu	100 %	5.120(12) MeV

Parent Nuclides

Direct parent isotope is: ¹⁶¹Pm.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 99) and isobaric (same nucleon number A = 161) with Samarium-161. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 99	Isobar A = 161
57	¹⁵⁶La
58	¹⁵⁷Ce
59	¹⁵⁸Pr
60	¹⁵⁹Nd	¹⁶¹Nd
61	¹⁶⁰Pm	¹⁶¹Pm
62	¹⁶¹Sm	¹⁶¹Sm
63	¹⁶²Eu	¹⁶¹Eu
64	¹⁶³Gd	¹⁶¹Gd
65	¹⁶⁴Tb	¹⁶¹Tb
66	¹⁶⁵Dy	¹⁶¹Dy
67	¹⁶⁶Ho	¹⁶¹Ho
68	¹⁶⁷Er	¹⁶¹Er
69	¹⁶⁸Tm	¹⁶¹Tm
70	¹⁶⁹Yb	¹⁶¹Yb
71	¹⁷⁰Lu	¹⁶¹Lu
72	¹⁷¹Hf	¹⁶¹Hf
73	¹⁷²Ta	¹⁶¹Ta
74	¹⁷³W	¹⁶¹W
75	¹⁷⁴Re	¹⁶¹Re
76	¹⁷⁵Os	¹⁶¹Os
77	¹⁷⁶Ir
78	¹⁷⁷Pt
79	¹⁷⁸Au
80	¹⁷⁹Hg
81	¹⁸⁰Tl
82	¹⁸¹Pb