Nuclide reference
At-211 — Astatine-211
The half-life of At-211 is 7.214 h. Main decay mode: electron capture to Po-211 (58.2%).
Identification
- Element
- Astatine (At)
- Atomic number Z
- 85
- Mass number A
- 211
- State
- Radioactive
Key quantities
- Half-life
- 7.214 h
- Specific activity
- 7.618e+16 Bq/g
- Gamma constant Γ
- —
- A1 / A2 for transport (SSR-6, НП-053-16)
- 20 TBq / 0.5 TBq
- D-value (НП-067-24)
- 0.5 TBq
Decay modes
Main gamma lines
| Energy, keV | Yield, % |
|---|---|
| 79.291 · X-ray line | 21.18 |
| 76.864 · X-ray line | 12.68 |
| 897.8 (Po-211) | 0.3207 |
| 569.65 (Po-211) | 0.3114 |
| 687 | 0.2606 |
| 669.78 | 0.003678 |
| 742.72 | 0.001045 |
| 892.4 | 0.0001421 |
Includes daughter nuclides in equilibrium: Po-211 (yield per decay of At-211); the emitting nuclide is in brackets. Equilibrium is reached in about 3.6 s.
Alpha and beta particles
| Radiation | Energy, keV | Yield, % |
|---|---|---|
| α | 5,869.5 | 41.8 |
| 7,450.3 (Po-211) | 57.57 | |
| 6,891.5 (Po-211) | 0.3178 | |
| 6,568.3 (Po-211) | 0.3125 |
Related calculators
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.