Lanthanum-146

Properties and data of the isotope ¹⁴⁶La.

Contents

General data

Name of the isotope:Lanthanum-146; La-146Symbol:¹⁴⁶La or 14657LaMass number A:146 (= number of nucleons)Atomic number Z:57 (= number of protons)Neutrons N:89Isotopic mass:145.92587(4) u (atomic weight of Lanthanum-146)Nuclide mass:145.8946031 u (calculated nuclear mass without electrons)Mass excess:-69.05165 MeVMass defect:1.291334348 u (per nucleus)Nuclear binding energy:1202.87019716 MeV (per nucleus)
8.23883697 MeV (average binding energy per nucleon)Separation energy:S_N = 4.29(4) MeV (first neutron)
S_P = 8.82(3) MeV (first proton)Half-life:6.1(3) sDecay constant λ:0.1136306853377 s^-1Specific activity α:4.719310297343 × 10⁺²⁰ Bq g^-1
12754892695.522 Ci g^-1Spin and parity:
(nuclear angular momentum)2-Year of discovery:1970

Radioactive Decay

Half-life T_½ = 6.1(3) s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹⁴⁶Ce	99.99 %	6.59(3) MeV
β^-, n	¹⁴⁵Ce	0.007 %

Parent Nuclides

Direct parent isotope is: ¹⁴⁶Ba.

Nuclear Isomers

Nuclear isomers or excited states with the activation energy in keV related to the ground state.

Nuclear Isomer	Excitation Energy	Half-life	Spin
^146mLa	130(130) keV	9.8(4) s	(6-)

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 89) and isobaric (same nucleon number A = 146) with Lanthanum-146. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 89	Isobar A = 146
50	¹³⁹Sn
51	¹⁴⁰Sb
52	¹⁴¹Te
53	¹⁴²I
54	¹⁴³Xe	¹⁴⁶Xe
55	¹⁴⁴Cs	¹⁴⁶Cs
56	¹⁴⁵Ba	¹⁴⁶Ba
57	¹⁴⁶La	¹⁴⁶La
58	¹⁴⁷Ce	¹⁴⁶Ce
59	¹⁴⁸Pr	¹⁴⁶Pr
60	¹⁴⁹Nd	¹⁴⁶Nd
61	¹⁵⁰Pm	¹⁴⁶Pm
62	¹⁵¹Sm	¹⁴⁶Sm
63	¹⁵²Eu	¹⁴⁶Eu
64	¹⁵³Gd	¹⁴⁶Gd
65	¹⁵⁴Tb	¹⁴⁶Tb
66	¹⁵⁵Dy	¹⁴⁶Dy
67	¹⁵⁶Ho	¹⁴⁶Ho
68	¹⁵⁷Er	¹⁴⁶Er
69	¹⁵⁸Tm	¹⁴⁶Tm
70	¹⁵⁹Yb
71	¹⁶⁰Lu
72	¹⁶¹Hf
73	¹⁶²Ta
74	¹⁶³W
75	¹⁶⁴Re
76	¹⁶⁵Os
77	¹⁶⁶Ir
78	¹⁶⁷Pt