Nuclide reference
Th-231 — Thorium-231
The half-life of Th-231 is 1.0633 d. Main decay mode: β⁻ decay to Pa-231 (100%).
Identification
- Element
- Thorium (Th)
- Atomic number Z
- 90
- Mass number A
- 231
- State
- Radioactive
Key quantities
- Half-life
- 1.0633 d
- Specific activity
- 1.967e+16 Bq/g
- Gamma constant Γ
- —
- A1 / A2 for transport (SSR-6, НП-053-16)
- 40 TBq / 0.02 TBq
- D-value (НП-067-24)
- 10 TBq
Decay modes
- β⁻ decay → Pa-231 — 100 %
Main gamma lines
| Energy, keV | Yield, % |
|---|---|
| 16.596 · X-ray line | 25.04 |
| 13.2828 · X-ray line | 23.69 |
| 25.64 | 14.12 |
| 84.214 | 6.6 |
| 89.95 | 0.9966 |
| 81.228 | 0.8976 |
| 58.57 | 0.462 |
| 102.27 | 0.4363 |
| 82.087 | 0.4158 |
| 72.751 | 0.2521 |
Lines of the bare nuclide (ENDF/B-VIII.0), without daughter ingrowth.
Alpha and beta particles
| Radiation | Energy, keV | Yield, % |
|---|---|---|
| β⁻, E max | 289.29 | 40 |
| 306.49 | 33 | |
| 207.2 | 12.8 | |
| 288.43 | 12 |
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.