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Radionuclide Dosimetric Data Sheets
Tellurium-121
Summary data
General
Classification
Isotope: Te-121
Atomic number (Z): 52
Mass number (A): 121
Neutron number (N): 69
Radioactive decay
Decay modes: Electron capture
Half-life: 19.16 [d]
Decay constant: 4.1871e-07 [1/s]
Daughters: Sb-121 (100.0%)
Radioactive daughters: None
Dosimetric constants
Mean alpha energy: 0.0 [MeV]
Mean electron energy: 0.00978 [MeV]
Mean photon energy: 0.57746 [MeV]
Air kerma rate constant, Γ10: 2.663e-17 [Gy·m2/Bq·s]
Air kerma coefficient, Kair: 2.663e-17 [Gy·m2/Bq·s]
Equilibrium dose constant for weakly-penetrating radiations (α and/or
electrons), Δwp: 1.567e-15 [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-:
1.567e-15 [Gy·kg/Bq·s]
Equilibrium dose constant for photons, Δp: 9.252e-14
[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/Te-121 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/Te-121 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/Te-121 Summary Spectrum.csv
|
Energy [MeV] |
Yield [#/nt] if > 0.01 |
Radiation type |
|
1.22327e-05 |
1.359e+01 |
X-ray |
|
3.59266e-03 |
3.261e-02 |
X-ray |
|
3.83820e-03 |
1.867e-02 |
X-ray |
|
2.60930e-02 |
2.170e-01 |
X-ray |
|
2.63486e-02 |
4.050e-01 |
X-ray |
|
2.96698e-02 |
3.692e-02 |
X-ray |
|
2.97173e-02 |
7.164e-02 |
X-ray |
|
3.03709e-02 |
1.490e-02 |
X-ray |
|
4.70472e-01 |
1.405e-02 |
Gamma |
|
5.07591e-01 |
1.767e-01 |
Gamma |
|
5.73139e-01 |
8.030e-01 |
Gamma |
|
1.68974e-05 |
6.692e+00 |
Auger electron |
|
2.73520e-05 |
2.262e+00 |
Auger electron |
|
1.21901e-04 |
7.585e-01 |
Auger electron |
|
2.85742e-04 |
1.411e-01 |
Auger electron |
|
4.22645e-04 |
1.690e+00 |
Auger electron |
|
5.05268e-04 |
5.121e-02 |
Auger electron |
|
2.96676e-03 |
6.650e-01 |
Auger electron |
|
3.52182e-03 |
1.800e-01 |
Auger electron |
|
4.09767e-03 |
1.238e-02 |
Auger electron |
|
6.65900e-03 |
1.122e-02 |
Conversion electron |
|
2.17904e-02 |
7.568e-02 |
Auger electron |
|
2.54497e-02 |
3.278e-02 |
Auger 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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