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Radionuclide Dosimetric Data Sheets
Yttrium-81
Summary data
General
Classification
Isotope: Y-81
Atomic number (Z): 39
Mass number (A): 81
Neutron number (N): 42
Radioactive decay
Decay modes: β+, Electron capture
Half-life: 70.4 [s]
Decay constant: 9.8458e-03 [1/s]
Daughters: Sr-81 (100.0%)
Radioactive daughters: Sr-81
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 1.96581 [MeV]
Mean photon energy: 1.17016 [MeV]
Air kerma rate constant, Γ10: 1.600e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 5.383e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 3.150e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for alphas, Δα: 0.000e+00
[Gy·kg/Bq·s]
Equilibrium dose constant for betas/electrons, Δβ-,β+,e-:
3.150e-13 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 1.875e-13
[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/Y-81 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/Y-81 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/Y-81 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/Y-81 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
2.09289e-05 |
6.831e+00 |
X-ray |
|
1.79939e-03 |
1.205e-02 |
X-ray |
|
9.82000e-03 |
1.996e-02 |
Gamma |
|
1.40549e-02 |
1.088e-01 |
X-ray |
|
1.41246e-02 |
2.090e-01 |
X-ray |
|
1.57867e-02 |
1.588e-02 |
X-ray |
|
1.57975e-02 |
3.096e-02 |
X-ray |
|
7.92300e-02 |
2.467e-01 |
Gamma |
|
1.01050e-01 |
2.745e-02 |
Gamma |
|
1.14340e-01 |
4.229e-02 |
Gamma |
|
1.15390e-01 |
2.115e-02 |
Gamma |
|
1.19760e-01 |
7.977e-02 |
Gamma |
|
1.24160e-01 |
4.107e-01 |
Gamma |
|
1.55200e-01 |
3.154e-02 |
Gamma |
|
2.21000e-01 |
3.339e-02 |
Gamma |
|
4.08180e-01 |
1.529e-01 |
Gamma |
|
5.11000e-01 |
1.955e+00 |
Annihilation photon |
|
1.77201e+00 |
1.468e-01 |
Positron |
|
1.90402e+00 |
2.679e-02 |
Positron |
|
1.95947e+00 |
4.465e-02 |
Positron |
|
1.96784e+00 |
3.175e-01 |
Positron |
|
1.99102e+00 |
3.175e-02 |
Positron |
|
2.01285e+00 |
4.266e-02 |
Positron |
|
2.02286e+00 |
1.786e-01 |
Positron |
|
2.02759e+00 |
1.786e-01 |
Positron |
|
1.36397e-05 |
1.906e+00 |
Auger electron |
|
7.49779e-05 |
1.899e+00 |
Auger electron |
|
9.38207e-05 |
8.046e-01 |
Auger electron |
|
1.01575e-04 |
1.876e-01 |
Auger electron |
|
1.09966e-04 |
9.205e-02 |
Auger electron |
|
1.57412e-03 |
7.880e-01 |
Auger electron |
|
1.71499e-03 |
7.019e-02 |
Auger electron |
|
7.61990e-03 |
7.463e-02 |
Conversion electron |
|
7.80790e-03 |
3.664e-02 |
Conversion electron |
|
7.87760e-03 |
6.571e-02 |
Conversion electron |
|
9.55047e-03 |
2.929e-02 |
Conversion electron |
|
1.20238e-02 |
1.244e-01 |
Auger electron |
|
1.37890e-02 |
4.215e-02 |
Auger electron |
|
6.31630e-02 |
4.803e-01 |
Conversion electron |
|
7.70299e-02 |
4.310e-02 |
Conversion electron |
|
7.72179e-02 |
2.027e-02 |
Conversion electron |
|
7.72876e-02 |
2.845e-02 |
Conversion electron |
|
7.89605e-02 |
1.580e-02 |
Conversion electron |
|
1.08093e-01 |
1.960e-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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