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Radionuclide Dosimetric Data Sheets
Einsteinium-254m
Summary data
General
Classification
Isotope: Es-254m
Atomic number (Z): 99
Mass number (A): 254
Neutron number (N): 155
Radioactive decay
Decay modes: α, β-, Electron capture,
Spontaneus fission
Half-life: 39.3 [h]
Decay constant: 4.8993e-06 [1/s]
Daughters: Fm-254 (98.0%), Bk-250 (0.32%), Cf-254 (0.076%), SF (0.045%)
Radioactive daughters: Fm-254, Bk-250, Cf-254
Dosimetric constants
Mean alpha energy: 0.0208 [MeV]
Mean electron energy: 0.24077 [MeV]
Mean photon energy: 0.47567 [MeV]
Air kerma rate constant, Γ10: 2.243e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 2.343e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 4.191e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 3.333e-15
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
3.858e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 7.621e-14
[Gy·kg/Bq·s]
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/Es-254m 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/Es-254m 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/Es-254m Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.64743e-05 |
7.326e+00 |
X-ray |
|
7.84444e-05 |
3.588e-02 |
X-ray |
|
4.08849e-03 |
5.909e-02 |
X-ray |
|
1.61332e-02 |
1.233e-02 |
X-ray |
|
1.64013e-02 |
1.081e-01 |
X-ray |
|
1.98996e-02 |
2.390e-02 |
X-ray |
|
2.20312e-02 |
1.272e-01 |
X-ray |
|
2.57302e-02 |
3.091e-02 |
X-ray |
|
5.84180e-01 |
2.842e-02 |
Gamma |
|
6.48690e-01 |
2.842e-01 |
Gamma |
|
6.88520e-01 |
1.225e-01 |
Gamma |
|
6.93670e-01 |
2.430e-01 |
Gamma |
|
1.24914e-01 |
1.568e-01 |
Beta |
|
1.37558e-01 |
5.586e-01 |
Beta |
|
3.60791e-01 |
2.646e-01 |
Beta |
|
1.27967e-04 |
1.917e+00 |
Auger electron |
|
1.91384e-04 |
1.193e+00 |
Auger electron |
|
3.92712e-04 |
1.948e+00 |
Auger electron |
|
7.01544e-04 |
3.575e-01 |
Auger electron |
|
2.41625e-03 |
7.155e-02 |
Auger electron |
|
2.92319e-03 |
6.122e-01 |
Auger electron |
|
3.65259e-03 |
1.590e-01 |
Auger electron |
|
4.45763e-03 |
1.080e-02 |
Auger electron |
|
1.23860e-02 |
1.439e-01 |
Auger electron |
|
1.66427e-02 |
7.876e-02 |
Auger electron |
|
1.73780e-02 |
1.162e-02 |
Conversion electron |
|
1.82080e-02 |
2.858e-01 |
Conversion electron |
|
2.09579e-02 |
1.010e-02 |
Auger electron |
|
2.41060e-02 |
2.245e-01 |
Conversion electron |
|
3.96074e-02 |
1.507e-01 |
Conversion electron |
|
4.50000e-02 |
5.643e-02 |
Conversion electron |
|
7.75580e-02 |
1.705e-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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