Nuclide reference
Th-229 — Thorium-229
The half-life of Th-229 is 7,340 years. Main decay mode: α decay to Ra-225 (100%).
Identification
- Element
- Thorium (Th)
- Atomic number Z
- 90
- Mass number A
- 229
- State
- Radioactive
Key quantities
- Half-life
- 7,340 years
- Specific activity
- 7.869e+9 Bq/g
- Gamma constant Γ
- —
- A1 / A2 for transport (SSR-6, НП-053-16)
- 5 TBq / 0.0005 TBq
- D-value (НП-067-24)
- 0.01 TBq
Decay modes
- α decay → Ra-225 — 100 %
Main gamma lines
| Energy, keV | Yield, % |
|---|---|
| 15.19 · X-ray line | 65.89 |
| 12.3318 · X-ray line | 57.99 |
| 40 (Ra-225) | 30 |
| 440.45 (Bi-213) | 25.94 |
| 11.1 | 12.31 |
| 218.12 (Fr-221) | 11.38 |
| 10.642 (Ac-225) | 8.5 |
| 193.52 | 4.413 |
| 210.853 | 2.77 |
| 86.4 | 2.565 |
Includes daughter nuclides in equilibrium: Ra-225, Ac-225, Fr-221, At-217, Bi-213, Po-213, Pb-209 (yield per decay of Th-229); the emitting nuclide is in brackets. Equilibrium is reached in about 100 d.
Alpha and beta particles
| Radiation | Energy, keV | Yield, % |
|---|---|---|
| α | 4,845.3 | 56.2 |
| 6,341 (Fr-221) | 83.4 | |
| 7,066.9 (At-217) | 99.89 | |
| 8,375.9 (Po-213) | 97.8 | |
| β⁻, E max | 316.91 (Ra-225) | 69.5 |
| 1,423 (Bi-213) | 65.8 | |
| 982.56 (Bi-213) | 30.74 | |
| 644 (Pb-209) | 100 |
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.