Nuclide reference
Ac-226 — Actinium-226
The half-life of Ac-226 is 1.2238 d. Main decay mode: β⁻ decay to Th-226 (83%).
Identification
- Element
- Actinium (Ac)
- Atomic number Z
- 89
- Mass number A
- 226
- State
- Radioactive
Key quantities
- Half-life
- 1.2238 d
- Specific activity
- 1.747e+16 Bq/g
- Gamma constant Γ
- —
- D-value (НП-067-24)
- —
Decay modes
Main gamma lines
| Energy, keV | Yield, % |
|---|---|
| 230 | 26.89 |
| 158.05 | 17.48 |
| 16.1429 · X-ray line | 6.321 |
| 88.4734 · X-ray line | 5.947 |
| 253.5 | 5.716 |
| 185.6 | 4.763 |
| 111.12 (Th-226) | 2.779 |
| 324.31 (Ra-222) | 2.341 |
| 242.12 (Th-226) | 0.7314 |
| 72.23 | 0.5647 |
Includes daughter nuclides in equilibrium: Th-226, Ra-222, Rn-218, Po-214 (yield per decay of Ac-226); the emitting nuclide is in brackets. Equilibrium is reached in about 3.6 h. Equilibrium with radon requires a sealed source.
Alpha and beta particles
| Radiation | Energy, keV | Yield, % |
|---|---|---|
| α | 6,336.8 (Th-226) | 63.77 |
| 6,559 (Ra-222) | 81.88 | |
| 7,129.2 (Rn-218) | 84.39 | |
| 7,686.8 (Po-214) | 84.49 | |
| β⁻, E max | 882.63 | 49 |
| 1,113 | 24 | |
| 1,040.8 | 10 | |
| 265.2 | 0.092 |
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.