Nuclide reference
Ac-227 — Actinium-227
The half-life of Ac-227 is 21.772 years. Main decay mode: β⁻ decay to Th-227 (98.62%).
Identification
- Element
- Actinium (Ac)
- Atomic number Z
- 89
- Mass number A
- 227
- State
- Radioactive
Key quantities
- Half-life
- 21.772 years
- Specific activity
- 2.676e+12 Bq/g
- Gamma constant Γ
- —
- A1 / A2 for transport (SSR-6, НП-053-16)
- 0.9 TBq / 0.00009 TBq
- D-value (НП-067-24)
- 0.04 TBq
Decay modes
Main gamma lines
| Energy, keV | Yield, % |
|---|---|
| 83.789 (Ra-223) · X-ray line | 24.07 |
| 235.96 (Th-227) | 17.3 |
| 81.071 (Ra-223) · X-ray line | 14.6 |
| 269.463 (Ra-223) | 13.95 |
| 351.07 (Bi-211) | 13.07 |
| 50.13 (Th-227) | 11.24 |
| 271.23 (Rn-219) | 10.84 |
| 256.23 (Th-227) | 9.393 |
| 401.81 (Rn-219) | 6.613 |
| 154.208 (Ra-223) | 5.72 |
Includes daughter nuclides in equilibrium: Th-227, Ra-223, Rn-219, Po-215, Pb-211, Bi-211, Tl-207 (yield per decay of Ac-227); the emitting nuclide is in brackets. Equilibrium is reached in about 130 d. Equilibrium with radon requires a sealed source.
Alpha and beta particles
| Radiation | Energy, keV | Yield, % |
|---|---|---|
| α | 4,953.3 | 0.6583 |
| 6,819.1 (Rn-219) | 79.7 | |
| 7,386.1 (Po-215) | 100.3 | |
| 6,622.9 (Bi-211) | 83.85 | |
| β⁻, E max | 44.8 | 54 |
| 35.5 | 35 | |
| 1,367 (Pb-211) | 91.64 | |
| 1,418 (Tl-207) | 99.83 |
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.