Samarium-140

Properties and data of the isotope ¹⁴⁰Sm.

Content

General data

Name of the isotope:Samarium-140; Sm-140Symbol:¹⁴⁰Sm or 14062SmMass number A:140 (= number of nucleons)Atomic number Z:62 (= number of protons)Neutrons N:78Isotopic mass:139.918995(13) u (atomic weight of Samarium-140)Nuclide mass:139.8849857 u (calculated nuclear mass without electrons)Mass excess:-75.45567 MeVMass defect:1.242020432 u (per nucleus)Nuclear binding energy:1156.93458029 MeV (per nucleus)
8.26381843 MeV (average binding energy per nucleon)Separation energy:S_N = 11.147(17) MeV (first neutron)
S_P = 5.244(18) MeV (first proton)Half-life:14.82(12) minDecay constant λ:0.00077951774691852 s^-1Specific activity α:3.377241492635 × 10⁺¹⁸ Bq g^-1
91276797.098268 Ci g^-1Spin and parity:
(nuclear angular momentum)0+Charge radius:4.9565(34) femtometer fmYear of discovery:1967

Radioactive Decay

Half-life T_½ = 14.82(12) min (minutes) respectively 8.892 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
EE/β⁺	¹⁴⁰Pm	100 %	2.758(27) MeV

Parent Nuclides

Direct parent isotope is: ¹⁴⁰Eu.

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 78) and isobaric (same nucleon number A = 140) with Samarium-140. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

OZ	Isotone N = 78	Isobar A = 140
43	¹²¹Tc
44	¹²²Ru
45	¹²³Rh
46	¹²⁴Pd
47	¹²⁵Ag
48	¹²⁶Cd
49	¹²⁷In
50	¹²⁸Sn
51	¹²⁹Sb	¹⁴⁰Sb
52	¹³⁰Te	¹⁴⁰Te
53	¹³¹I	¹⁴⁰I
54	¹³²Xe	¹⁴⁰Xe
55	¹³³Cs	¹⁴⁰Cs
56	¹³⁴Ba	¹⁴⁰Ba
57	¹³⁵La	¹⁴⁰La
58	¹³⁶Ce	¹⁴⁰Ce
59	¹³⁷Pr	¹⁴⁰Pr
60	¹³⁸Nd	¹⁴⁰Nd
61	¹³⁹Pm	¹⁴⁰Pm
62	¹⁴⁰Sm	¹⁴⁰Sm
63	¹⁴¹Eu	¹⁴⁰Eu
64	¹⁴²Gd	¹⁴⁰Gd
65	¹⁴³Tb	¹⁴⁰Tb
66	¹⁴⁴Dy	¹⁴⁰Dy
67	¹⁴⁵Ho	¹⁴⁰Ho
68	¹⁴⁶Er
69	¹⁴⁷Tm
70	¹⁴⁸Yb
71	¹⁴⁹Lu