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Radionuclide Dosimetric Data Sheets

Actinium-231

Summary data

General

Classification

Isotope:  Ac-231
Atomic number (Z):  89
Mass number (A):  231
Neutron number (N):  142

Radioactive decay

Decay modes:  β-
Half-life:  7.5 [m]
Decay constant:  1.5403e-03 [1/s]
Daughters:  Th-231 (100.0%)
Radioactive daughters:  Th-231

Dosimetric constants

Mean alpha energy:  0.0 [MeV]
Mean electron energy:  0.63605 [MeV]
Mean photon energy:  0.41898 [MeV]
Air kerma rate constant, Γ10:  2.239e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair:  2.239e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or electrons), Δwp:  1.019e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα:  0.000e+00 [Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:  1.019e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp:  6.713e-14 [Gy·kg/Bq·s]

Dose point kernels (plot)

Dose point kernel source:  Graves, et al. Medical Physics. 2019 Nov.; 46(11):5284-5293.

Note: Bins are spaced every 0.1 mm until a radius of 10 cm, and every 1 mm until a radius of 2 m.

Download tabulated dose point kernel file here:  www.mirdsoft.org/products/MIRDspecs/Ac-231 DPK.csv

Summary spectra (plot)

Spectra source:  ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).

Download tabulated summary spectra file here:  www.mirdsoft.org/products/MIRDspecs/Ac-231 Summary Spectrum.csv

Beta spectra (plot)

Spectra source:  ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).

Download tabulated beta spectra file here:  www.mirdsoft.org/products/MIRDspecs/Ac-231 Beta Spectrum.csv

 

Tabulated data

Summary spectra (table)

Spectra source:  ICRP Publication 107: Nuclear Decay Data for Dosimetric Calculations. Ann. ICRP 2008, 38 (3).

Note: Radiations with yield < 0.01 are excluded from the table, but are available in the linked *.csv data.

Download tabulated summary spectra file here:  www.mirdsoft.org/products/MIRDspecs/Ac-231 Summary Spectrum.csv

 

Energy [MeV]

Yield [#/nt] if > 0.01

Radiation type

8.22400e-05

8.567e+00

X-ray

3.06047e-03

4.752e-02

X-ray

1.28126e-02

1.270e-02

X-ray

1.29764e-02

1.117e-01

X-ray

1.56384e-02

2.307e-02

X-ray

1.62776e-02

6.607e-02

X-ray

1.90652e-02

1.468e-02

X-ray

9.03299e-02

1.355e-01

X-ray

9.37949e-02

2.190e-01

X-ray

1.05278e-01

2.510e-02

X-ray

1.06073e-01

4.895e-02

X-ray

1.09154e-01

1.251e-02

X-ray

1.43650e-01

3.230e-02

Gamma

1.85680e-01

1.577e-01

Gamma

1.98900e-01

2.736e-02

Gamma

2.21380e-01

1.721e-01

Gamma

2.40870e-01

3.990e-02

Gamma

2.71900e-01

2.508e-02

Gamma

2.82460e-01

3.800e-01

Gamma

3.07050e-01

2.983e-01

Gamma

3.68930e-01

1.490e-01

Gamma

3.72000e-01

1.520e-02

Gamma

4.07800e-01

3.230e-02

Gamma

5.17431e-01

6.188e-02

Beta

5.32817e-01

8.583e-01

Beta

6.66310e-01

7.984e-02

Beta

5.13369e-05

2.064e+00

Auger electron

1.32420e-04

2.282e+00

Auger electron

1.50396e-04

1.312e-02

Auger electron

1.88011e-04

1.289e+00

Auger electron

4.97008e-04

3.383e-01

Auger electron

1.41312e-03

1.546e-01

Auger electron

2.31241e-03

7.476e-01

Auger electron

2.72499e-03

1.281e-01

Auger electron

9.72089e-03

1.941e-01

Auger electron

1.28463e-02

9.652e-02

Auger electron

1.60058e-02

1.133e-02

Auger electron

2.15220e-02

9.256e-02

Conversion electron

3.79638e-02

2.484e-02

Conversion electron

7.55700e-02

1.411e-02

Conversion electron

8.87900e-02

6.225e-02

Conversion electron

1.11270e-01

2.910e-01

Conversion electron

1.30760e-01

4.928e-02

Conversion electron

1.61790e-01

1.762e-02

Conversion electron

1.72350e-01

1.309e-02

Conversion electron

1.78422e-01

1.054e-02

Conversion electron

2.00902e-01

4.905e-02

Conversion electron

2.17344e-01

1.314e-02

Conversion electron

 

Useful Links

Isotope decay characteristics are periodically updated as better measurements can be made - changes that may not be reflected on this page. Please see useful links:

National Nuclear Data Center (NNDC):  https://www.nndc.bnl.gov/nudat3/mird/

International Atomic Energy Agency (IAEA) Livechart:  https://www-nds.iaea.org/relnsd/vcharthtml/VChartHTML.html

Reference Links

ICRP Report 107: https://www.icrp.org/publication.asp?id=ICRP%20Publication%20107

Graves et al. Dose Point Kernels: https://doi.org/10.1002/mp.13789

MIRD Decay Schemes 2nd Edition: https://sites.snmmi.org/SNMMI-MAIN/iCore/Store/StoreLayouts/Item_Detail.aspx?iProductCode=0-932004-80-6

 

 

 

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