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Radionuclide Dosimetric Data Sheets

Fermium-251

Isotope:  Fm-251
Atomic number (Z):  100
Mass number (A):  251
Neutron number (N):  151

Decay modes:  α, β+, Electron capture
Half-life:  5.3 [h]
Decay constant:  3.6328e-05 [1/s]
Daughters:  Es-251 (98.2%), Cf-247 (1.8%)
Radioactive daughters:  Es-251, Cf-247

Mean alpha energy:  0.1251 [MeV]
Mean electron energy:  0.0337 [MeV]
Mean photon energy:  0.15875 [MeV]
Air kerma rate constant, Γ₁₀:  1.342e-17 [Gy·m²/Bq·s]
Air kerma coefficient, K_air:  1.343e-17 [Gy·m²/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or electrons), Δ_wp:  2.544e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δ_α:  2.004e-14 [Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δ_β-,β+,e-:  5.399e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δ_p:  2.543e-14 [Gy·kg/Bq·s]

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-251 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/Fm-251 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/Fm-251 Summary Spectrum.csv

 

Energy [MeV]	Yield [#/nt] if > 0.01	Radiation type
7.45605e-05	1.800e-01	X-ray
7.53998e-05	2.001e+01	X-ray
3.98116e-03	1.396e-01	X-ray
1.34560e-02	1.503e-02	X-ray
1.57835e-02	2.202e-02	X-ray
1.60394e-02	1.932e-01	X-ray
1.94489e-02	4.246e-02	X-ray
2.02594e-02	2.022e-02	X-ray
2.13814e-02	1.134e-01	X-ray
2.15768e-02	1.417e-02	X-ray
2.49830e-02	2.733e-02	X-ray
1.13103e-01	2.163e-01	X-ray
1.18701e-01	3.327e-01	X-ray
1.32545e-01	3.903e-02	X-ray
1.33863e-01	7.730e-02	X-ray
1.37794e-01	2.081e-02	X-ray
4.53100e-01	1.453e-02	Gamma
8.80800e-01	2.190e-02	Gamma
1.14414e-04	4.888e-02	Auger electron
1.20727e-04	5.458e+00	Auger electron
1.92776e-04	2.906e-02	Auger electron
1.96556e-04	3.228e+00	Auger electron
2.23389e-04	2.280e-02	Auger electron
3.36271e-04	4.762e-02	Auger electron
3.68865e-04	5.251e+00	Auger electron
6.90060e-04	1.381e+00	Auger electron
2.53476e-03	2.254e-01	Auger electron
2.79975e-03	1.495e-02	Auger electron
2.87535e-03	1.513e+00	Auger electron
3.05280e-03	7.062e-01	Conversion electron
3.58824e-03	3.826e-01	Auger electron
4.39244e-03	2.575e-02	Auger electron
8.30000e-03	2.758e-01	Conversion electron
1.18517e-02	2.399e-01	Auger electron
1.59669e-02	1.299e-01	Auger electron
2.01335e-02	1.647e-02	Auger electron
2.06560e-02	7.009e-02	Conversion electron
2.14730e-02	2.025e-02	Conversion electron
2.70710e-02	1.001e-02	Conversion electron
4.22328e-02	2.574e-02	Conversion electron
8.88227e-02	1.233e-02	Auger electron
6.83268e+00	1.569e-02	Alpha
1.10723e-01	1.569e-02	Alpha recoil

 

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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