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Radionuclide Dosimetric Data Sheets
Einsteinium-251
Summary data
General
Classification
Isotope: Es-251
Atomic number (Z): 99
Mass number (A): 251
Neutron number (N): 152
Radioactive decay
Decay modes: α, Electron capture
Half-life: 33.0 [h]
Decay constant: 5.8346e-06 [1/s]
Daughters: Cf-251 (99.5%), Bk-247 (0.5%)
Radioactive daughters: Cf-251, Bk-247
Dosimetric constants
Mean alpha energy: 0.0329 [MeV]
Mean electron energy: 0.05221 [MeV]
Mean photon energy: 0.10161 [MeV]
Air kerma rate constant, Γ10: 1.667e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 1.667e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.364e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 5.271e-15
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
8.365e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 1.628e-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-251 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/Es-251 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.45513e-05 |
2.141e+01 |
X-ray |
|
3.86032e-03 |
1.554e-01 |
X-ray |
|
1.31965e-02 |
2.589e-02 |
X-ray |
|
1.54368e-02 |
3.857e-02 |
X-ray |
|
1.56809e-02 |
3.385e-01 |
X-ray |
|
1.90028e-02 |
7.395e-02 |
X-ray |
|
1.96961e-02 |
2.922e-02 |
X-ray |
|
1.97994e-02 |
1.520e-02 |
X-ray |
|
2.07498e-02 |
1.150e-01 |
X-ray |
|
2.09431e-02 |
2.118e-02 |
X-ray |
|
2.42553e-02 |
2.749e-02 |
X-ray |
|
1.10388e-01 |
2.070e-01 |
X-ray |
|
1.15701e-01 |
3.202e-01 |
X-ray |
|
1.29279e-01 |
3.749e-02 |
X-ray |
|
1.30526e-01 |
7.408e-02 |
X-ray |
|
1.34357e-01 |
1.984e-02 |
X-ray |
|
1.77600e-01 |
2.159e-02 |
Gamma |
|
1.14364e-04 |
5.838e+00 |
Auger electron |
|
1.94525e-04 |
3.433e+00 |
Auger electron |
|
2.11710e-04 |
2.684e-02 |
Auger electron |
|
3.36543e-04 |
5.666e+00 |
Auger electron |
|
6.69716e-04 |
1.147e+00 |
Auger electron |
|
2.38116e-03 |
3.198e-01 |
Auger electron |
|
2.79584e-03 |
1.752e+00 |
Auger electron |
|
3.46239e-03 |
4.226e-01 |
Auger electron |
|
4.22408e-03 |
2.753e-02 |
Auger electron |
|
4.89500e-03 |
3.636e-01 |
Conversion electron |
|
1.12786e-02 |
3.922e-01 |
Auger electron |
|
1.52454e-02 |
2.102e-01 |
Auger electron |
|
1.70700e-02 |
8.065e-02 |
Conversion electron |
|
1.78972e-02 |
1.639e-02 |
Conversion electron |
|
1.92447e-02 |
2.634e-02 |
Auger electron |
|
1.97202e-02 |
2.982e-01 |
Conversion electron |
|
2.48240e-02 |
1.103e-01 |
Conversion electron |
|
4.19700e-02 |
1.384e-01 |
Conversion electron |
|
8.68283e-02 |
1.241e-02 |
Auger electron |
|
1.04053e-01 |
1.686e-02 |
Conversion electron |
|
1.26653e-01 |
1.497e-02 |
Conversion electron |
|
1.51553e-01 |
2.559e-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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