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Radionuclide Dosimetric Data Sheets
Cesium-138m
Summary data
General
Classification
Isotope: Cs-138m
Atomic number (Z): 55
Mass number (A): 138
Neutron number (N): 83
Radioactive decay
Decay modes: β-, Internal transition
Half-life: 2.91 [m]
Decay constant: 3.9699e-03 [1/s]
Daughters: Cs-138 (81.0%), Ba-138 (19.0%)
Radioactive daughters: Cs-138
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 0.3201 [MeV]
Mean photon energy: 0.41487 [MeV]
Air kerma rate constant, Γ10: 1.599e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 1.599e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 5.129e-14 [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-:
5.129e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 6.647e-14
[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-138m 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-138m 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-138m 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-138m Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
1.86018e-05 |
6.275e-01 |
X-ray |
|
2.18904e-05 |
9.094e+00 |
X-ray |
|
4.27312e-03 |
3.172e-02 |
X-ray |
|
4.61551e-03 |
1.498e-02 |
X-ray |
|
3.06218e-02 |
1.145e-01 |
X-ray |
|
3.09789e-02 |
2.115e-01 |
X-ray |
|
3.22056e-02 |
1.794e-02 |
X-ray |
|
3.49256e-02 |
2.004e-02 |
X-ray |
|
3.49943e-02 |
3.885e-02 |
X-ray |
|
1.12500e-01 |
1.520e-02 |
Gamma |
|
1.91700e-01 |
1.539e-01 |
Gamma |
|
3.24500e-01 |
1.178e-02 |
Gamma |
|
4.63000e-01 |
1.862e-01 |
Gamma |
|
1.43600e+00 |
1.900e-01 |
Gamma |
|
1.25012e+00 |
2.742e-02 |
Beta |
|
1.34844e+00 |
1.959e-02 |
Beta |
|
1.40074e+00 |
1.430e-01 |
Beta |
|
1.08630e-05 |
1.339e-01 |
Auger electron |
|
2.10618e-05 |
1.221e+00 |
Auger electron |
|
4.14585e-05 |
4.314e+00 |
Auger electron |
|
4.69142e-05 |
7.738e-02 |
Auger electron |
|
4.87948e-05 |
2.125e-01 |
Auger electron |
|
1.14796e-04 |
3.044e-02 |
Auger electron |
|
1.18374e-04 |
5.428e-01 |
Auger electron |
|
3.48688e-04 |
1.153e-01 |
Auger electron |
|
5.28867e-04 |
1.173e+00 |
Auger electron |
|
5.52013e-04 |
6.976e-02 |
Auger electron |
|
6.54432e-04 |
7.716e-02 |
Auger electron |
|
3.44503e-03 |
4.573e-01 |
Auger electron |
|
3.56612e-03 |
2.735e-02 |
Auger electron |
|
4.16706e-03 |
1.410e-01 |
Auger electron |
|
4.91873e-03 |
1.087e-02 |
Auger electron |
|
2.53980e-02 |
3.004e-02 |
Auger electron |
|
2.98089e-02 |
1.365e-02 |
Auger electron |
|
4.39150e-02 |
4.447e-01 |
Conversion electron |
|
7.42151e-02 |
1.329e-01 |
Conversion electron |
|
7.45368e-02 |
2.209e-02 |
Conversion electron |
|
7.48939e-02 |
1.245e-01 |
Conversion electron |
|
7.89093e-02 |
6.544e-02 |
Conversion electron |
|
7.99000e-02 |
1.669e-02 |
Conversion electron |
|
1.54251e-01 |
2.361e-02 |
Conversion 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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