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Radionuclide Dosimetric Data Sheets
Fermium-255
Summary data
General
Classification
Isotope: Fm-255
Atomic number (Z): 100
Mass number (A): 255
Neutron number (N): 155
Radioactive decay
Decay modes: α, Spontaneus fission
Half-life: 20.07 [h]
Decay constant: 9.5935e-06 [1/s]
Daughters: Cf-251 (100.0%), SF (2.3e-05%)
Radioactive daughters: Cf-251
Dosimetric constants
Mean alpha energy: 7.1292 [MeV]
Mean electron energy: 0.09541 [MeV]
Mean photon energy: 0.01696 [MeV]
Air kerma rate constant, Γ10: 1.319e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 1.319e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.158e-12 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 1.142e-12
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
1.529e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 2.717e-15
[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/Fm-255 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/Fm-255 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/Fm-255 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.46195e-05 |
2.240e+01 |
X-ray |
|
3.87231e-03 |
1.569e-01 |
X-ray |
|
1.31965e-02 |
2.300e-02 |
X-ray |
|
1.54368e-02 |
3.428e-02 |
X-ray |
|
1.56809e-02 |
3.008e-01 |
X-ray |
|
1.90028e-02 |
6.571e-02 |
X-ray |
|
1.96961e-02 |
2.041e-02 |
X-ray |
|
1.97994e-02 |
1.351e-02 |
X-ray |
|
2.07498e-02 |
1.523e-01 |
X-ray |
|
2.09431e-02 |
1.479e-02 |
X-ray |
|
2.42552e-02 |
3.641e-02 |
X-ray |
|
1.14196e-04 |
6.272e+00 |
Auger electron |
|
1.95043e-04 |
3.538e+00 |
Auger electron |
|
2.13019e-04 |
2.855e-02 |
Auger electron |
|
3.39938e-04 |
5.810e+00 |
Auger electron |
|
5.70000e-04 |
1.700e-01 |
Conversion electron |
|
6.96554e-04 |
1.284e+00 |
Auger electron |
|
2.31576e-03 |
2.609e-01 |
Auger electron |
|
2.81019e-03 |
1.757e+00 |
Auger electron |
|
3.07200e-03 |
1.964e-02 |
Conversion electron |
|
3.48239e-03 |
4.254e-01 |
Auger electron |
|
4.25238e-03 |
2.783e-02 |
Auger electron |
|
4.89500e-03 |
3.810e-01 |
Conversion electron |
|
1.13998e-02 |
3.624e-01 |
Auger electron |
|
1.53761e-02 |
1.944e-01 |
Auger electron |
|
1.78972e-02 |
1.596e-01 |
Conversion electron |
|
1.93890e-02 |
2.440e-02 |
Auger electron |
|
1.97202e-02 |
3.125e-01 |
Conversion electron |
|
2.25880e-02 |
6.888e-02 |
Conversion electron |
|
2.30010e-02 |
5.963e-02 |
Conversion electron |
|
2.48240e-02 |
1.156e-01 |
Conversion electron |
|
2.79010e-02 |
5.472e-02 |
Conversion electron |
|
3.18550e-02 |
2.507e-02 |
Conversion electron |
|
3.24300e-02 |
2.044e-01 |
Conversion electron |
|
3.32350e-02 |
3.428e-02 |
Conversion electron |
|
3.39570e-02 |
2.754e-02 |
Conversion electron |
|
4.27262e-02 |
3.606e-02 |
Conversion electron |
|
4.78300e-02 |
1.332e-02 |
Conversion electron |
|
5.33732e-02 |
6.187e-02 |
Conversion electron |
|
5.49002e-02 |
1.071e-02 |
Conversion electron |
|
5.54300e-02 |
1.028e-02 |
Conversion electron |
|
5.56780e-02 |
4.840e-02 |
Conversion electron |
|
5.62350e-02 |
2.011e-01 |
Conversion electron |
|
5.84770e-02 |
2.315e-02 |
Conversion electron |
|
6.09910e-02 |
3.250e-02 |
Conversion electron |
|
6.15480e-02 |
1.347e-01 |
Conversion electron |
|
7.58162e-02 |
2.387e-02 |
Conversion electron |
|
7.63732e-02 |
9.908e-02 |
Conversion electron |
|
8.14770e-02 |
3.670e-02 |
Conversion electron |
|
6.96236e+00 |
4.989e-02 |
Alpha |
|
7.02143e+00 |
9.245e-01 |
Alpha |
|
1.11026e-01 |
4.989e-02 |
Alpha recoil |
|
1.11968e-01 |
9.245e-01 |
Alpha recoil |
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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