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Radionuclide Dosimetric Data Sheets
Fermium-256
Summary data
General
Classification
Isotope: Fm-256
Atomic number (Z): 100
Mass number (A): 256
Neutron number (N): 156
Radioactive decay
Decay modes: α, Spontaneus fission
Half-life: 157.6 [m]
Decay constant: 7.3302e-05 [1/s]
Daughters: Cf-252 (8.1%), SF (91.9%)
Radioactive daughters: Cf-252
Dosimetric constants
Mean alpha energy: 0.5686 [MeV]
Mean electron energy: 6.3116 [MeV]
Mean photon energy: 12.4371 [MeV]
Air kerma rate constant, Γ10: 8.556e-20 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 2.062e-15 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.102e-12 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 9.110e-14
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
1.011e-12 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 1.993e-12
[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-256 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-256 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-256 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
7.45995e-05 |
1.144e-01 |
X-ray |
|
1.48000e-02 |
7.752e-02 |
Prompt gamma |
|
3.00000e-02 |
9.408e-02 |
Delayed gamma |
|
3.14000e-02 |
2.022e-01 |
Prompt gamma |
|
5.00000e-02 |
9.408e-02 |
Delayed gamma |
|
7.00000e-02 |
9.408e-02 |
Delayed gamma |
|
7.53000e-02 |
1.703e-02 |
Prompt gamma |
|
8.53000e-02 |
2.415e-02 |
Prompt gamma |
|
9.00000e-02 |
9.408e-02 |
Delayed gamma |
|
9.53000e-02 |
3.446e-02 |
Prompt gamma |
|
1.10000e-01 |
9.408e-02 |
Delayed gamma |
|
1.10000e-01 |
1.146e-01 |
Prompt gamma |
|
1.30000e-01 |
9.408e-02 |
Delayed gamma |
|
1.30000e-01 |
1.146e-01 |
Prompt gamma |
|
1.50000e-01 |
9.408e-02 |
Delayed gamma |
|
1.50000e-01 |
1.146e-01 |
Prompt gamma |
|
1.70000e-01 |
9.408e-02 |
Delayed gamma |
|
1.70000e-01 |
1.146e-01 |
Prompt gamma |
|
1.90000e-01 |
9.408e-02 |
Delayed gamma |
|
1.90000e-01 |
1.146e-01 |
Prompt gamma |
|
2.25000e-01 |
2.309e-01 |
Delayed gamma |
|
2.25000e-01 |
2.873e-01 |
Prompt gamma |
|
2.75000e-01 |
2.309e-01 |
Delayed gamma |
|
2.75000e-01 |
2.873e-01 |
Prompt gamma |
|
3.25000e-01 |
2.309e-01 |
Delayed gamma |
|
3.25000e-01 |
2.873e-01 |
Prompt gamma |
|
3.75000e-01 |
2.309e-01 |
Delayed gamma |
|
3.75000e-01 |
2.873e-01 |
Prompt gamma |
|
4.25000e-01 |
2.873e-01 |
Prompt gamma |
|
4.40000e-01 |
6.500e-01 |
Delayed gamma |
|
4.75000e-01 |
2.873e-01 |
Prompt gamma |
|
5.25000e-01 |
2.873e-01 |
Prompt gamma |
|
5.40000e-01 |
5.046e-01 |
Delayed gamma |
|
5.75000e-01 |
2.873e-01 |
Prompt gamma |
|
6.40000e-01 |
3.934e-01 |
Delayed gamma |
|
6.49000e-01 |
5.534e-01 |
Prompt gamma |
|
7.40000e-01 |
3.079e-01 |
Delayed gamma |
|
7.49000e-01 |
4.625e-01 |
Prompt gamma |
|
8.40000e-01 |
2.395e-01 |
Delayed gamma |
|
8.49000e-01 |
3.880e-01 |
Prompt gamma |
|
9.49000e-01 |
3.242e-01 |
Prompt gamma |
|
1.04900e+00 |
2.718e-01 |
Prompt gamma |
|
1.10000e+00 |
1.009e+00 |
Delayed gamma |
|
1.14900e+00 |
2.268e-01 |
Prompt gamma |
|
1.25000e+00 |
1.899e-01 |
Prompt gamma |
|
1.35000e+00 |
1.588e-01 |
Prompt gamma |
|
1.45000e+00 |
1.326e-01 |
Prompt gamma |
|
1.56000e+00 |
6.158e-01 |
Delayed gamma |
|
1.73000e+00 |
4.707e-01 |
Prompt gamma |
|
2.00000e+00 |
3.250e-01 |
Delayed gamma |
|
2.23000e+00 |
2.734e-01 |
Prompt gamma |
|
2.40000e+00 |
2.395e-01 |
Delayed gamma |
|
2.73000e+00 |
1.580e-01 |
Prompt gamma |
|
2.80000e+00 |
1.368e-01 |
Delayed gamma |
|
3.23000e+00 |
9.169e-02 |
Prompt gamma |
|
3.25000e+00 |
1.026e-01 |
Delayed gamma |
|
3.73000e+00 |
5.321e-02 |
Prompt gamma |
|
3.75000e+00 |
7.355e-02 |
Delayed gamma |
|
4.23000e+00 |
3.086e-02 |
Prompt gamma |
|
4.25000e+00 |
3.592e-02 |
Delayed gamma |
|
4.73000e+00 |
1.785e-02 |
Prompt gamma |
|
4.75000e+00 |
1.710e-02 |
Delayed gamma |
|
5.23000e+00 |
1.040e-02 |
Prompt gamma |
|
1.18883e+00 |
5.309e+00 |
Delayed beta |
|
1.14523e-04 |
3.091e-02 |
Auger electron |
|
1.90969e-04 |
1.869e-02 |
Auger electron |
|
3.34944e-04 |
3.027e-02 |
Auger electron |
|
6.87213e+00 |
1.215e-02 |
Alpha |
|
6.91713e+00 |
6.885e-02 |
Alpha |
|
1.09152e-01 |
1.215e-02 |
Alpha recoil |
|
1.09867e-01 |
6.885e-02 |
Alpha recoil |
|
9.72779e+01 |
1.838e+00 |
Fission fragment |
|
2.00326e+00 |
3.685e+00 |
Neutron |
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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