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Radionuclide Dosimetric Data Sheets
Francium-221
Summary data
General
Classification
Isotope: Fr-221
Atomic number (Z): 87
Mass number (A): 221
Neutron number (N): 134
Radioactive decay
Decay modes: α
Half-life: 4.9 [m]
Decay constant: 2.3576e-03 [1/s]
Daughters: At-217 (100.0%)
Radioactive daughters: At-217
Dosimetric constants
Mean alpha energy: 6.4198 [MeV]
Mean electron energy: 0.0089 [MeV]
Mean photon energy: 0.02941 [MeV]
Air kerma rate constant, Γ10: 1.743e-18 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 1.743e-18 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.030e-12 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 1.029e-12
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
1.426e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 4.712e-15
[Gy·kg/Bq·s]
Dose point kernels (plot)
Dose point kernel source: Graves, et al. Medical Physics. 2019 Nov.; 46(11):5284-5293.
Note: Bins are spaced every 0.1 mm until a radius of 10 cm, and every 1 mm until a radius of 2 m.
Download tabulated dose point kernel file here: www.mirdsoft.org/products/MIRDspecs/Fr-221 DPK.csv
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/Fr-221 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/Fr-221 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
4.42881e-05 |
7.188e-01 |
X-ray |
|
8.18531e-02 |
1.472e-02 |
X-ray |
|
2.18190e-01 |
1.158e-01 |
Gamma |
|
3.81201e-05 |
1.782e-01 |
Auger electron |
|
1.05088e-04 |
2.182e-01 |
Auger electron |
|
1.76894e-04 |
1.193e-01 |
Auger electron |
|
4.54470e-04 |
2.801e-02 |
Auger electron |
|
2.07289e-03 |
6.449e-02 |
Auger electron |
|
3.43201e-03 |
1.026e-02 |
Conversion electron |
|
8.81746e-03 |
1.850e-02 |
Auger electron |
|
1.22122e-01 |
1.591e-02 |
Conversion electron |
|
2.01350e-01 |
1.135e-02 |
Conversion electron |
|
6.12641e+00 |
1.497e-01 |
Alpha |
|
6.24295e+00 |
1.329e-02 |
Alpha |
|
6.34065e+00 |
8.271e-01 |
Alpha |
|
1.13003e-01 |
1.497e-01 |
Alpha recoil |
|
1.15152e-01 |
1.329e-02 |
Alpha recoil |
|
1.16954e-01 |
8.271e-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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