Nuclide reference
Th-226 — Thorium-226
The half-life of Th-226 is 30.57 min. Main decay mode: α decay to Ra-222 (100%).
Identification
- Element
- Thorium (Th)
- Atomic number Z
- 90
- Mass number A
- 226
- State
- Radioactive
Key quantities
- Half-life
- 30.57 min
- Specific activity
- 1.007e+18 Bq/g
- Gamma constant Γ
- —
- D-value (НП-067-24)
- —
Decay modes
- α decay → Ra-222 — 100 %
Main gamma lines
| Energy, keV | Yield, % |
|---|---|
| 15.2081 · X-ray line | 3.815 |
| 111.12 | 3.29 |
| 12.3298 · X-ray line | 3.24 |
| 324.31 (Ra-222) | 2.826 |
| 242.12 | 0.866 |
| 131.02 | 0.278 |
| 206.23 | 0.189 |
| 609.31 (Rn-218) | 0.1265 |
| 190.3 | 0.109 |
| 799.7 (Po-214) | 0.01056 |
Includes daughter nuclides in equilibrium: Ra-222, Rn-218, Po-214 (yield per decay of Th-226); the emitting nuclide is in brackets. Equilibrium is reached in about 4.3 min. In transient equilibrium a daughter's activity exceeds the parent's, so a yield can be above 100%. Equilibrium with radon requires a sealed source.
Alpha and beta particles
| Radiation | Energy, keV | Yield, % |
|---|---|---|
| α | 6,336.8 | 75.5 |
| 6,559 (Ra-222) | 98.85 | |
| 7,129.2 (Rn-218) | 101.9 | |
| 7,686.8 (Po-214) | 102 |
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.