Samarium-155

Properties and data of the isotope ¹⁵⁵Sm.

Content

General data

Name of the isotope:Samarium-155; Sm-155Symbol:¹⁵⁵Sm or 15562SmMass number A:155 (= number of nucleons)Atomic number Z:62 (= number of protons)Neutrons N:93Isotopic mass:154.9246471(16) u (atomic weight of Samarium-155)Nuclide mass:154.8906378 u (calculated nuclear mass without electrons)Mass excess:-70.19077 MeVMass defect:1.366342072 u (per nucleus)Nuclear binding energy:1272.73944202 MeV (per nucleus)
8.21122221 MeV (average binding energy per nucleon)Separation energy:S_N = 5.80696(27) MeV (first neutron)
S_P = 8.97(5) MeV (first proton)Half-life:22.3(2) minDecay constant λ:0.00051804722014944 s^-1Specific activity α:2.025813851843 × 10⁺¹⁸ Bq g^-1
54751725.725492 Ci g^-1Spin and parity:
(nuclear angular momentum)3/2-Magnetic dipole moment:μ(μ_N) = 1.13(13)Nuclear g-factor:g_l = 0.75333333333333Year of discovery:1951

Radioactive Decay

Half-life T_½ = 22.3(2) min (minutes) respectively 1.338 × 10³ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁵⁵Eu	100 %	1.6273(12) MeV

Parent Nuclides

Direct parent isotope is: ¹⁵⁵Pm.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 93) and isobaric (same nucleon number A = 155) with Samarium-155. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 93	Isobar A = 155
54	¹⁴⁷Xe
55	¹⁴⁸Cs
56	¹⁴⁹Ba
57	¹⁵⁰La	¹⁵⁵La
58	¹⁵¹Ce	¹⁵⁵Ce
59	¹⁵²Pr	¹⁵⁵Pr
60	¹⁵³Nd	¹⁵⁵Nd
61	¹⁵⁴Pm	¹⁵⁵Pm
62	¹⁵⁵Sm	¹⁵⁵Sm
63	¹⁵⁶Eu	¹⁵⁵Eu
64	¹⁵⁷Gd	¹⁵⁵Gd
65	¹⁵⁸Tb	¹⁵⁵Tb
66	¹⁵⁹Dy	¹⁵⁵Dy
67	¹⁶⁰Ho	¹⁵⁵Ho
68	¹⁶¹Er	¹⁵⁵Er
69	¹⁶²Tm	¹⁵⁵Tm
70	¹⁶³Yb	¹⁵⁵Yb
71	¹⁶⁴Lu	¹⁵⁵Lu
72	¹⁶⁵Hf	¹⁵⁵Hf
73	¹⁶⁶Ta	¹⁵⁵Ta
74	¹⁶⁷W
75	¹⁶⁸Re
76	¹⁶⁹Os
77	¹⁷⁰Ir
78	¹⁷¹Pt
79	¹⁷²Au
80	¹⁷³Hg