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Radionuclide Dosimetric Data Sheets
Thorium-226
Summary data
General
Classification
Isotope: Th-226
Atomic number (Z): 90
Mass number (A): 226
Neutron number (N): 136
Radioactive decay
Decay modes: α
Half-life: 30.57 [m]
Decay constant: 3.7790e-04 [1/s]
Daughters: Ra-222 (100.0%)
Radioactive daughters: Ra-222
Dosimetric constants
Mean alpha energy: 6.4218 [MeV]
Mean electron energy: 0.02111 [MeV]
Mean photon energy: 0.0089 [MeV]
Air kerma rate constant, Γ10: 2.398e-18 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 2.398e-18 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.032e-12 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 1.029e-12
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
3.382e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 1.426e-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/Th-226 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/Th-226 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/Th-226 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.12319e-05 |
2.185e+00 |
X-ray |
|
2.89299e-03 |
1.112e-02 |
X-ray |
|
1.23447e-02 |
2.247e-02 |
X-ray |
|
1.53013e-02 |
3.083e-02 |
X-ray |
|
1.11120e-01 |
3.290e-02 |
Gamma |
|
2.58036e-05 |
6.003e-01 |
Auger electron |
|
1.20967e-04 |
6.081e-01 |
Auger electron |
|
1.81472e-04 |
3.466e-01 |
Auger electron |
|
4.78355e-04 |
8.756e-02 |
Auger electron |
|
2.02182e-03 |
1.223e-02 |
Auger electron |
|
2.22805e-03 |
1.916e-01 |
Auger electron |
|
2.60325e-03 |
3.093e-02 |
Auger electron |
|
9.58515e-03 |
5.171e-02 |
Auger electron |
|
1.25254e-02 |
2.513e-02 |
Auger electron |
|
9.25600e-02 |
8.214e-02 |
Conversion electron |
|
9.56640e-02 |
5.732e-02 |
Conversion electron |
|
1.07346e-01 |
3.927e-02 |
Conversion electron |
|
1.11120e-01 |
1.327e-02 |
Conversion electron |
|
6.09942e+00 |
1.261e-02 |
Alpha |
|
6.22809e+00 |
2.281e-01 |
Alpha |
|
6.33724e+00 |
7.553e-01 |
Alpha |
|
1.09971e-01 |
1.261e-02 |
Alpha recoil |
|
1.12291e-01 |
2.281e-01 |
Alpha recoil |
|
1.14259e-01 |
7.553e-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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