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Actinium-204

Properties and data of the isotope 204Ac.


Content

Actinium-204 is a radioisotope of the element actinium, whose atomic nucleus has 115 neutrons in addition to the element-specific 89 protons, resulting in a mass number of 204.

The generation of this short-lived isotope was first reported in 2022; it was produced in a fusion-evaporation reaction: 169Tm(40Ca,5n) 204Ac [1].

See also: list of Actinium isotopes.

 

General data

Name of the isotope:Actinium-204; Ac-204Symbol:204Ac or 20489AcMass number A:204 (= number of nucleons)Atomic number Z:89 (= number of protons)Neutrons N:115Isotopic mass:204 u (atomic weight of Actinium-204)Nuclide mass:203.9511826 u (calculated nuclear mass without electrons)Mass excess:0 MeVMass defect:1.692893188 u (per nucleus)Nuclear binding energy:1576.91984726 MeV (per nucleus)
7.72999925 MeV (average binding energy per nucleon)
Half-life:7.4 msDecay constant λ:93.668537913506 s-1Specific activity α:2.765123183624 × 10+23 Bq g-1
7473305901688.6 Ci g-1
Spin and parity:
(nuclear angular momentum)
Year of discovery:2022

 

Radioactive Decay

Half-life T½ = 7.4 ms respectively 7.4 × 10-3 seconds s.

Decay modeDaughterProbabilityDecay energyγ energy
(intensity)
α200Fr?

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 115) and isobaric (same nucleon number A = 204) with Actinium-204. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

OZIsotone N = 115Isobar A = 204
70185Yb
71186Lu
72187Hf
73188Ta
74189W
75190Re
76191Os
77192Ir204Ir
78193Pt204Pt
79194Au204Au
80195Hg204Hg
81196Tl204Tl
82197Pb204Pb
83198Bi204Bi
84199Po204Po
85200At204At
86201Rn204Rn
87202Fr204Fr
88203Ra204Ra
89204Ac204Ac

 

External data and identifiers

Adopted Levels, Gammas:NuDat 204Ac

 

Literature and References

[1] - M. H. Huang, Z. G. Gan, Z. Y. Zhang et al.:
α Decay of the new Isotope 204Ac.
In: Physics Letters B, (2022), DOI 10.1016/j.physletb.2022.137484.

 


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Last update: 2022-12-21


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