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Radionuclide Dosimetric Data Sheets
Polonium-209
Summary data
General
Classification
Isotope: Po-209
Atomic number (Z): 84
Mass number (A): 209
Neutron number (N): 125
Radioactive decay
Decay modes: α, Electron capture
Half-life: 102.0 [y]
Decay constant: 2.1534e-10 [1/s]
Daughters: Pb-205 (99.5%), Bi-209 (0.48%)
Radioactive daughters: Pb-205
Dosimetric constants
Mean alpha energy: 4.9528 [MeV]
Mean electron energy: 0.00303 [MeV]
Mean photon energy: 0.00629 [MeV]
Air kerma rate constant, Γ10: 3.296e-19 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 3.296e-19 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 7.940e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 7.935e-13
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
4.855e-16 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 1.008e-15
[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/Po-209 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/Po-209 Summary 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/Po-209 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
2.66001e-05 |
4.200e+00 |
X-ray |
|
3.24784e-05 |
6.042e-02 |
X-ray |
|
4.07189e-05 |
1.409e-02 |
Auger electron |
|
4.23843e-05 |
1.160e+00 |
Auger electron |
|
8.96061e-05 |
1.921e-02 |
Auger electron |
|
9.72207e-05 |
1.108e+00 |
Auger electron |
|
1.73721e-04 |
1.023e-02 |
Auger electron |
|
1.80767e-04 |
1.107e+00 |
Auger electron |
|
2.32900e-03 |
7.955e-01 |
Conversion electron |
|
4.88335e+00 |
7.889e-01 |
Alpha |
|
4.88561e+00 |
1.972e-01 |
Alpha |
|
9.53469e-02 |
7.889e-01 |
Alpha recoil |
|
9.53909e-02 |
1.972e-01 |
Alpha recoil |
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
MIRDsoft MIRDspecs version 20250101 (www.mirdsoft.org)
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