Nuclide reference
Rb-81 — Rubidium-81
The half-life of Rb-81 is 4.572 h. Main decay mode: β⁺ decay / electron capture to Kr-81m (95.67%).
Identification
- Element
- Rubidium (Rb)
- Atomic number Z
- 37
- Mass number A
- 81
- State
- Radioactive
Key quantities
- Half-life
- 4.572 h
- Specific activity
- 3.131e+17 Bq/g
- Gamma constant Γ
- —
- A1 / A2 for transport (SSR-6, НП-053-16)
- 2 TBq / 0.8 TBq
- D-value (НП-067-24)
- 0.1 TBq
Decay modes
Main gamma lines
| Energy, keV | Yield, % |
|---|---|
| 190.46 (Kr-81m) | 64.76 |
| 510.999 · annihilation 511 keV | 54.39 |
| 446.15 | 23.5 |
| 12.648 · X-ray line | 23.37 |
| 12.596 · X-ray line | 12.12 |
| 510.43 | 5.405 |
| 456.73 | 3.055 |
| 537.6 | 2.256 |
| 1,368.1 | 0.8695 |
| 803.72 | 0.8437 |
Includes daughter nuclides in equilibrium: Kr-81m (yield per decay of Rb-81); the emitting nuclide is in brackets. Equilibrium is reached in about 1.5 min.
Alpha and beta particles
| Radiation | Energy, keV | Yield, % |
|---|---|---|
| β⁺, E max | 1,026.3 | 25 |
| 580.15 | 1.82 | |
| 516.14 | 0.28 | |
| 1,217 | 0.06 |
For β⁺ the endpoint (maximum) energy of the spectrum is given. ENDF/B-VIII.0.
Related calculators
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.