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Radionuclide Dosimetric Data Sheets
Thorium-232
Summary data
General
Classification
Isotope: Th-232
Atomic number (Z): 90
Mass number (A): 232
Neutron number (N): 142
Radioactive decay
Decay modes: α
Half-life: 14050000000.0 [y]
Decay constant: 1.5633e-18 [1/s]
Daughters: Ra-228 (100.0%)
Radioactive daughters: Ra-228
Dosimetric constants
Mean alpha energy: 4.0688 [MeV]
Mean electron energy: 0.01261 [MeV]
Mean photon energy: 0.00148 [MeV]
Air kerma rate constant, Γ10: 2.257e-18 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 2.257e-18 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 6.539e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 6.519e-13
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
2.020e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 2.371e-16
[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-232 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-232 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-232 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.12319e-05 |
2.257e+00 |
X-ray |
|
2.89132e-03 |
1.150e-02 |
X-ray |
|
1.23447e-02 |
2.454e-02 |
X-ray |
|
1.53013e-02 |
3.046e-02 |
X-ray |
|
2.57692e-05 |
6.201e-01 |
Auger electron |
|
1.20725e-04 |
6.279e-01 |
Auger electron |
|
1.81331e-04 |
3.578e-01 |
Auger electron |
|
4.72331e-04 |
8.993e-02 |
Auger electron |
|
2.15783e-03 |
1.048e-02 |
Auger electron |
|
2.22619e-03 |
1.985e-01 |
Auger electron |
|
2.60079e-03 |
3.202e-02 |
Auger electron |
|
9.51569e-03 |
5.402e-02 |
Auger electron |
|
1.24509e-02 |
2.623e-02 |
Auger electron |
|
4.52500e-02 |
8.460e-02 |
Conversion electron |
|
4.83540e-02 |
7.152e-02 |
Conversion electron |
|
6.00363e-02 |
4.320e-02 |
Conversion electron |
|
6.38100e-02 |
1.453e-02 |
Conversion electron |
|
3.94965e+00 |
2.171e-01 |
Alpha |
|
4.01236e+00 |
7.822e-01 |
Alpha |
|
6.93372e-02 |
2.171e-01 |
Alpha recoil |
|
7.04381e-02 |
7.822e-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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