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Radionuclide Dosimetric Data Sheets
Cesium-131
Summary data
General
Classification
Isotope: Cs-131
Atomic number (Z): 55
Mass number (A): 131
Neutron number (N): 76
Radioactive decay
Decay modes: Electron capture
Half-life: 9.689 [d]
Decay constant: 8.2800e-07 [1/s]
Daughters: Xe-131 (100.0%)
Radioactive daughters: None
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 0.00635 [MeV]
Mean photon energy: 0.02315 [MeV]
Air kerma rate constant, Γ10: 4.286e-18 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 4.286e-18 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.017e-15 [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-:
1.017e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 3.709e-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/Cs-131 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/Cs-131 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/Cs-131 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
1.66176e-05 |
1.186e+01 |
X-ray |
|
4.09719e-03 |
3.740e-02 |
X-ray |
|
4.41300e-03 |
2.174e-02 |
X-ray |
|
2.94521e-02 |
2.131e-01 |
X-ray |
|
2.97812e-02 |
3.946e-01 |
X-ray |
|
3.35665e-02 |
3.704e-02 |
X-ray |
|
3.36295e-02 |
7.181e-02 |
X-ray |
|
3.44080e-02 |
1.515e-02 |
X-ray |
|
2.62367e-05 |
1.855e+00 |
Auger electron |
|
3.62530e-05 |
5.640e+00 |
Auger electron |
|
1.23767e-04 |
7.000e-01 |
Auger electron |
|
3.26299e-04 |
1.411e-01 |
Auger electron |
|
5.05373e-04 |
1.539e+00 |
Auger electron |
|
6.17976e-04 |
8.817e-02 |
Auger electron |
|
3.32891e-03 |
6.060e-01 |
Auger electron |
|
4.00671e-03 |
1.798e-01 |
Auger electron |
|
4.71182e-03 |
1.367e-02 |
Auger electron |
|
2.44715e-02 |
5.991e-02 |
Auger electron |
|
2.86854e-02 |
2.680e-02 |
Auger 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
MIRDsoft MIRDspecs version 20250101 (www.mirdsoft.org)
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