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Radionuclide Dosimetric Data Sheets

Cesium-125

Isotope:  Cs-125
Atomic number (Z):  55
Mass number (A):  125
Neutron number (N):  70

Decay modes:  β+, Electron capture
Half-life:  45.0 [m]
Decay constant:  2.5672e-04 [1/s]
Daughters:  Xe-125 (100.0%)
Radioactive daughters:  Xe-125

Mean alpha energy:  0.0 [MeV]
Mean electron energy:  0.35242 [MeV]
Mean photon energy:  0.75504 [MeV]
Air kerma rate constant, Γ₁₀:  1.490e-17 [Gy·m²/Bq·s]
Air kerma coefficient, K_air:  3.025e-17 [Gy·m²/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or electrons), Δ_wp:  5.646e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δ_α:  0.000e+00 [Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δ_β-,β+,e-:  5.646e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δ_p:  1.210e-13 [Gy·kg/Bq·s]

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-125 DPK.csv

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-125 Summary Spectrum.csv

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-125 Beta Spectrum.csv

 

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-125 Summary Spectrum.csv

 

Energy [MeV]	Yield [#/nt] if > 0.01	Radiation type
1.66176e-05	7.864e+00	X-ray
4.09719e-03	2.517e-02	X-ray
4.41300e-03	1.461e-02	X-ray
2.94521e-02	1.449e-01	X-ray
2.97812e-02	2.683e-01	X-ray
3.35665e-02	2.519e-02	X-ray
3.36295e-02	4.884e-02	X-ray
3.44080e-02	1.030e-02	X-ray
1.12000e-01	8.618e-02	Gamma
3.35000e-01	2.046e-02	Gamma
4.12000e-01	5.270e-02	Gamma
4.28000e-01	1.581e-02	Gamma
5.11000e-01	7.931e-01	Annihilation photon
5.26000e-01	2.455e-01	Gamma
5.40000e-01	3.100e-02	Gamma
6.00000e-01	3.100e-02	Gamma
7.12000e-01	3.534e-02	Gamma
6.12414e-01	1.397e-02	Positron
6.89312e-01	1.198e-02	Positron
6.96040e-01	8.583e-02	Positron
8.82594e-01	1.497e-02	Positron
9.33525e-01	2.695e-01	Positron
2.61871e-05	1.226e+00	Auger electron
3.62434e-05	3.740e+00	Auger electron
1.23740e-04	4.614e-01	Auger electron
3.21787e-04	8.843e-02	Auger electron
5.05170e-04	1.025e+00	Auger electron
6.17448e-04	5.864e-02	Auger electron
3.32541e-03	4.037e-01	Auger electron
4.00272e-03	1.198e-01	Auger electron
2.44715e-02	4.074e-02	Auger electron
2.86854e-02	1.823e-02	Auger electron
7.74440e-02	4.679e-02	Conversion electron

 

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

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

 

 

 

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