Nuclide reference
I-129 — Iodine-129
The half-life of I-129 is 15.7 million years. Main decay mode: β⁻ decay to Xe-129 (100%).
Identification
- Element
- Iodine (I)
- Atomic number Z
- 53
- Mass number A
- 129
- State
- Radioactive
Key quantities
- Half-life
- 15.7 million years
- Specific activity
- 6,531,000 Bq/g
- Gamma constant Γ
- —
- A1 / A2 for transport (SSR-6, НП-053-16)
- unlimited / unlimited
- D-value (НП-067-24)
- —
Decay modes
- β⁻ decay → Xe-129 — 100 %
Main gamma lines
| Energy, keV | Yield, % |
|---|---|
| 29.778 · X-ray line | 36.73 |
| 29.458 · X-ray line | 19.94 |
| 39.578 | 7.51 |
Lines of the bare nuclide (ENDF/B-VIII.0), without daughter ingrowth.
Alpha and beta particles
| Radiation | Energy, keV | Yield, % |
|---|---|---|
| β⁻, E max | 154.42 | 100 |
For β⁻ the endpoint (maximum) energy of the spectrum is given. ENDF/B-VIII.0.
Related calculators
Other isotopes of this element
Reference data vs computed valuesHalf-life, gamma lines and D-value are reference data (ENDF/B-VIII.0, НП-067-24).Gamma constant Γ is H*(10) at 1 m computed from ICRP-107 spectra (NIST µ_en/ρ, ICRP-74 Table A.21) including short-lived progeny in equilibrium (e.g. Cs-137/Ba-137m, Ra-226 series); specific activity uses molar mass M ≈ mass number A.K-series X-ray energies are from NIST SRD 128 (Deslattes et al., 2003): in ENDF/B-VIII.0 they are given to 1 % and shifted by up to 0.7 keV for heavy elements. L-series lines and all yields are ENDF/B-VIII.0.