Cesium-138m1

Properties and data of the isotope ^138m1Cs.

Contents

See also: List of individual Cesium isotopes (and general data sources).

General data

Name of the isotope:Cesium-138m1; Cs-138m1Symbol:^138m1Cs or 138m155CsMass number A:138 (= number of nucleons)Atomic number Z:55 (= number of protons)Neutrons N:83Isotopic mass:137.911017(10) u (atomic weight of Cesium-138m1)
Excitation energy: 79.9(3) keVNuclide mass:137.8808471 u (calculated nuclear mass without electrons)Mass excess:-82.88713 MeVMass defect:1.238547788 u (per nucleus)Nuclear binding energy:1153.69983324 MeV (per nucleus)
8.36014372 MeV (average binding energy per nucleon)Half-life:2.91(8) minDecay constant λ:0.0039699151234819 s^-1Specific activity α:1.745064823036 × 10⁺¹⁹ Bq g^-1
471639141.36124 Ci g^-1Spin and parity:
(nuclear angular momentum)6-Magnetic dipole moment:μ(μ_N) = +1.710(9)Quadrupole moment Q:- 0.40(3) barn (100 fm²)Nuclear g-factor:g_l = 0.285

Radioactive Decay

Half-life T_½ = 2.91(8) min (minutes) respectively 1.746 × 10² seconds s.

Decay mode	Daughter	Probability	Decay energy	γ energy (intensity)
β^-	¹³⁸Ba	19(2) %
Iso	¹³⁸Cs	81(2) %

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
¹³⁸Cs		32.5(2) min	3-

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 83) and isobaric (same nucleon number A = 138) with Cesium-138m1. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

Z	Isotone N = 83	Isobar A = 138
46	¹²⁹Pd
47	¹³⁰Ag
48	¹³¹Cd
49	¹³²In
50	¹³³Sn	¹³⁸Sn
51	¹³⁴Sb	¹³⁸Sb
52	¹³⁵Te	¹³⁸Te
53	¹³⁶I	¹³⁸I
54	¹³⁷Xe	¹³⁸Xe
55	¹³⁸Cs	¹³⁸Cs
56	¹³⁹Ba	¹³⁸Ba
57	¹⁴⁰La	¹³⁸La
58	¹⁴¹Ce	¹³⁸Ce
59	¹⁴²Pr	¹³⁸Pr
60	¹⁴³Nd	¹³⁸Nd
61	¹⁴⁴Pm	¹³⁸Pm
62	¹⁴⁵Sm	¹³⁸Sm
63	¹⁴⁶Eu	¹³⁸Eu
64	¹⁴⁷Gd	¹³⁸Gd
65	¹⁴⁸Tb	¹³⁸Tb
66	¹⁴⁹Dy	¹³⁸Dy
67	¹⁵⁰Ho
68	¹⁵¹Er
69	¹⁵²Tm
70	¹⁵³Yb
71	¹⁵⁴Lu
72	¹⁵⁵Hf
73	¹⁵⁶Ta
74	¹⁵⁷W