Nuclide reference
At-218 — Astatine-218
The half-life of At-218 is 1.5 s. Main decay mode: α decay to Bi-214 (99.9%).
Identification
- Element
- Astatine (At)
- Atomic number Z
- 85
- Mass number A
- 218
- State
- Radioactive
Key quantities
- Half-life
- 1.5 s
- Specific activity
- 1.277e+21 Bq/g
- Gamma constant Γ
- —
- D-value (НП-067-24)
- —
Decay modes
Main gamma lines
| Energy, keV | Yield, % |
|---|---|
| 62.69 | 89.91 |
Lines of the nuclide itself (ENDF/B-VIII.0).
Alpha and beta particles
| Radiation | Energy, keV | Yield, % |
|---|---|---|
| α | 6,693 | 89.91 |
| 6,653 | 6.394 | |
| 6,756 | 3.596 | |
| 7,686.8 (Po-214) | 0.1024 | |
| β⁻, E max | 2,881 | 0.1 |
For β⁻ the endpoint (maximum) energy of the spectrum is given. ENDF/B-VIII.0. Includes daughter nuclides in equilibrium: Po-214 (yield per decay of At-218); the emitting nuclide is in brackets. Equilibrium is reached in about 0.25 s.
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.