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Promethium-129

Properties and data of the isotope 129Pm.


Contents

See also: list of Promethium isotopes.

 

General data

Name of the isotope:Promethium-129; Pm-129Symbol:129Pm or 12961PmMass number A:129 (= number of nucleons)Atomic number Z:61 (= number of protons)Neutrons N:68Isotopic mass:128.94323(32) u (atomic weight of Promethium-129)Nuclide mass:128.9097692 u (calculated nuclear mass without electrons)Mass excess:-52.88091 MeVMass defect:1.12331124 u (per nucleus)Nuclear binding energy:1046.35768019 MeV (per nucleus)
8.11129985 MeV (average binding energy per nucleon)
Separation energy:SN = 13.17(42) MeV (first neutron)Half-life:2.4(9) sDecay constant λ:0.28881132523331 s-1Specific activity α:1.358798814453 × 10+21 Bq g-1
36724292282.516 Ci g-1
Spin and parity:
(nuclear angular momentum)
(5/2-)Year of discovery:2004

 

Radioactive Decay

Half-life T½ = 2.4(9) s.

Decay
mode
DaughterProbabilityDecay energyγ energy
(intensity)
EC/β+129Ndca. 100 %9.43(36) MeV
EC, p129Pr?
p128Nd?

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 68) and isobaric (same nucleon number A = 129) with Promethium-129. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

ZIsotone N = 68Isobar A = 129
38106Sr
39107Y
40108Zr
41109Nb
42110Mo
43111Tc
44112Ru
45113Rh
46114Pd129Pd
47115Ag129Ag
48116Cd129Cd
49117In129In
50118Sn129Sn
51119Sb129Sb
52120Te129Te
53121I129I
54122Xe129Xe
55123Cs129Cs
56124Ba129Ba
57125La129La
58126Ce129Ce
59127Pr129Pr
60128Nd129Nd
61129Pm129Pm
62130Sm129Sm
63131Eu

 

External data and identifiers

Adopted Levels, Gammas:NuDat 129Pm

 


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Last update: 2020-10-20


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