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Actinium-227

Properties and data of the isotope 227Ac.

 

Actinium-227 is the radioisotope of the element actinium, whose atomic nucleus has 138 neutrons in addition to the element-specific 89 protons, resulting in a mass number of 227: 227 Ac.

See also: list of Actinium isotopes.

 

General data

Name of the isotope:Actinium-227; Ac-227Namen:ActiniumSymbol:227AcMass number A:227Atomic number Z:89 (= number of protons)Neutrons N:138Isotopic mass:227.0277507(21) u (atomic weight of Actinium-227)Nuclide mass:226.9789333 u (calculated nuclear mass without electrons)Mass excess:25.84961 MeVMass defect:1.864435556 u (per nucleus)Nuclear binding energy:1736.7105338 MeV (per nucleus)
7.6507072 MeV (average binding energy per nucleon)
Separation energy:SN = 6.531(3) MeV (first neutron)
SP = 5.1072(22) MeV (first proton)
Cross section:σ(n.γ) = 880(70) barn (thermal neutron capture cross-section)Half-life:21.772(3) aDecay constant λ:1.009533019919 × 10-9 s-1Spin and parity:3/2-Year of discovery:1902

 

Radioactive Decay

Half-life T½ = 21.772(3) a respectively 6.86601792 × 108 seconds s.

Decay modeDaughterProbabilityDecay energyγ energy
(intensity)
α223Fr1,3800(36) %5,04227(14) MeV
β-227Th98,6200(36) %0,0448(8) MeV

 

Actinium-227 radioactive decay

 

Parent Nuclides

Direct parent isotopes are: 231Pa, 227Ra.

 

Occurrence

Comparison of the natural Actinium isotopes including isotopic abundance (proportion of the isotope mixture):

 

Atomic Mass maQuantityHalf-lifeSpin
Actinium
Isotopic mixture
227,027752408 u100 %
Isotope 223Ac223,019137(8) utrace2.10(5) min(5/2-)
Isotope 227Ac227,0277507(21) u100 %21.772(3) a3/2-

 

NMR data

227Ac belongs to the NMR active Nuclides.

Isotope:227Ac-NMRQuantity:100 %Spin:3/2-Nuclearmagnetic moment
μ/μN:
+ 1,1(1)Gyromagnetic ratio
107 rad T-1 s-1:
3,5Quadrupole moment
Q fm-2:
+ 170(20)Resonance frequency
v0 at 1 T:
5,6Relative Sensitivity:0,01131 (H0 = const.)
0,6565 (v0 = const.)
[related to 1H = 1,000]

 

Radiation Protection

The German Radiation Protection Ordinance, for example, specifies the following limit values for the isotope Actinium-227 (exemption limits, clearance values and other values as a radioactive or highly radioactive source of radiation (HASS)):

Isotope:Ac-227+Exemption level:103 BqExemption level per gram:0,01 Bq/g
Unrestricted handling of solids and liquids.
Activity HASS:0,04 TBqSurface contamination:1 Bq cm-2Half-life:21.8 a

 

Isotones and Isobars

The following table shows the atomic nuclei that are isotonic (same neutron number N = 138) and isobaric (same nucleon number A = 227) with Actinium-227. Naturally occurring isotopes are marked in green; light green = naturally occurring radionuclides.

 

OZIsotone N = 138Isobar A = 227
82220Pb
83221Bi
84222Po227Po
85223At227At
86224Rn227Rn
87225Fr227Fr
88226Ra227Ra
89227Ac227Ac
90228Th227Th
91229Pa227Pa
92230U227U
93231Np227Np
94232Pu
95233Am
96234Cm
97235Bk

 

External data and identifiers

CAS:14952-40-0InChI Key:QQINRWTZWGJFDB-IGMARMGPSA-NSMILES:[227Ac]PubChem:ID 105152Adopted Levels, Gammas:NuDat 227Ac

 


Category: Isotopes

Last update: 03.12.2022



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