Europium-155

Properties and data of the isotope ¹⁵⁵Eu.

Content

General data

Name of the isotope:Europium-155; Eu-155Symbol:¹⁵⁵Eu or 15563EuMass number A:155 (= number of nucleons)Atomic number Z:63 (= number of protons)Neutrons N:92Isotopic mass:154.9229001(15) u (atomic weight of Europium-155)Nuclide mass:154.8883423 u (calculated nuclear mass without electrons)Mass excess:-71.81809 MeVMass defect:1.367249188 u (per nucleus)Nuclear binding energy:1273.58441513 MeV (per nucleus)
8.21667365 MeV (average binding energy per nucleon)Separation energy:S_N = 8.1513(4) MeV (first neutron)
S_P = 6.6519(12) MeV (first proton)Half-life:4.753(14) aDecay constant λ:4.624341558598 × 10^-9 s^-1Specific activity α:18083400162560 Bq g^-1
488.74054493405 Ci g^-1Spin and parity:
(nuclear angular momentum)5/2+Magnetic dipole moment:μ(μ_N) = + 1.520(2)Quadrupole moment Q:2.494(20) barn (100 fm²)Nuclear g-factor:g_l = 0.608Charge radius:5.1221(69) femtometer fmYear of discovery:1947

Radioactive Decay

Half-life T_½ = 4.753(14) a respectively 1.49891 × 10⁸ seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁵⁵Gd	100 %	0.2518(9) MeV

Parent Nuclides

Direct parent isotope is: ¹⁵⁵Sm.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 92) and isobaric (same nucleon number A = 155) with Europium-155. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 92	Isobar A = 155
53	¹⁴⁵I
54	¹⁴⁶Xe
55	¹⁴⁷Cs
56	¹⁴⁸Ba
57	¹⁴⁹La	¹⁵⁵La
58	¹⁵⁰Ce	¹⁵⁵Ce
59	¹⁵¹Pr	¹⁵⁵Pr
60	¹⁵²Nd	¹⁵⁵Nd
61	¹⁵³Pm	¹⁵⁵Pm
62	¹⁵⁴Sm	¹⁵⁵Sm
63	¹⁵⁵Eu	¹⁵⁵Eu
64	¹⁵⁶Gd	¹⁵⁵Gd
65	¹⁵⁷Tb	¹⁵⁵Tb
66	¹⁵⁸Dy	¹⁵⁵Dy
67	¹⁵⁹Ho	¹⁵⁵Ho
68	¹⁶⁰Er	¹⁵⁵Er
69	¹⁶¹Tm	¹⁵⁵Tm
70	¹⁶²Yb	¹⁵⁵Yb
71	¹⁶³Lu	¹⁵⁵Lu
72	¹⁶⁴Hf	¹⁵⁵Hf
73	¹⁶⁵Ta	¹⁵⁵Ta
74	¹⁶⁶W
75	¹⁶⁷Re
76	¹⁶⁸Os
77	¹⁶⁹Ir
78	¹⁷⁰Pt
79	¹⁷¹Au
80	¹⁷²Hg