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Radionuclide Dosimetric Data Sheets
Cesium-126
Summary data
General
Classification
Isotope: Cs-126
Atomic number (Z): 55
Mass number (A): 126
Neutron number (N): 71
Radioactive decay
Decay modes: β+, Electron capture
Half-life: 1.64 [m]
Decay constant: 7.0442e-03 [1/s]
Daughters: Xe-126 (100.0%)
Radioactive daughters: None
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 1.31927 [MeV]
Mean photon energy: 1.1545 [MeV]
Air kerma rate constant, Γ10: 1.246e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 4.383e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 2.114e-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-:
2.114e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 1.850e-13
[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-126 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-126 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/Cs-126 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/Cs-126 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
1.66177e-05 |
2.347e+00 |
X-ray |
|
2.94521e-02 |
4.332e-02 |
X-ray |
|
2.97812e-02 |
8.023e-02 |
X-ray |
|
3.36295e-02 |
1.460e-02 |
X-ray |
|
3.88660e-01 |
4.070e-01 |
Gamma |
|
4.34010e-01 |
1.087e-02 |
Gamma |
|
4.91270e-01 |
5.047e-02 |
Gamma |
|
5.11000e-01 |
1.621e+00 |
Annihilation photon |
|
8.79900e-01 |
1.294e-02 |
Gamma |
|
9.25240e-01 |
4.558e-02 |
Gamma |
|
9.54717e-01 |
1.111e-02 |
Positron |
|
1.12196e+00 |
3.403e-02 |
Positron |
|
1.32281e+00 |
2.903e-02 |
Positron |
|
1.55220e+00 |
2.452e-01 |
Positron |
|
1.73496e+00 |
4.864e-01 |
Positron |
|
2.61864e-05 |
3.660e-01 |
Auger electron |
|
3.62432e-05 |
1.116e+00 |
Auger electron |
|
1.23736e-04 |
1.377e-01 |
Auger electron |
|
3.21708e-04 |
2.636e-02 |
Auger electron |
|
5.05166e-04 |
3.058e-01 |
Auger electron |
|
6.17439e-04 |
1.750e-02 |
Auger electron |
|
3.32531e-03 |
1.205e-01 |
Auger electron |
|
4.00261e-03 |
3.575e-02 |
Auger electron |
|
2.44715e-02 |
1.218e-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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