Isotope: Actinium-206
General data
| Element name | Actinium |
|---|---|
| Chemical symbol | Ac |
| Atomic number Z | 89 |
| Isotope name (symbol) | Actinium-206 (Ac-206) |
| Neutron number N | 117 |
| Mass number A=Z+N | 206 |
Ground state
| Half-life | 27 ± 8 ms |
|---|---|
| Spin / Parity | (3+) |
| Mass excess | 13480 ± 70 keV |
Decay branches
α ≈ 100%Isomers
| Isomer | Energy | Half-life | Spin / Parity | Decay branches |
|---|---|---|---|---|
| Isomer 1 | 200 ± 70 keV | 33 +22/−9 ms | (10-) | α ≈ 100% |
Produced by decay of
NNDC data contain no decay that leads to this isotope.
Many isotopes are also produced, often mainly, in nuclear reactions (e.g. Co-60 from Co-59 by neutron capture, C-14 from nitrogen-14 in the atmosphere) and in fission (e.g. Cs-137, I-131) - those routes are not listed here.
Radioactive decay series
- Actinium-206 27 ms
- Francium-202 364 ms
- Astatine-198 4.47 s
- Bismuth-194 100 s · 90.0%
- Polonium-198 1.76 min · 10.0%
- Lead-194 10.7 min · 95.3%
- Thallium-194 33.3 min · 95.3%
- Mercury-194 450 a · 95.3%
- Gold-194 38.06 h · 95.3%
- Platinum-194 stable · 95.3%
- Bismuth-198 10.3 min · 4.3%
- Lead-198 2.4 h · 4.3%
- Thallium-198 5.3 h · 4.3%
- Mercury-198 stable · 4.3%
- Thallium-190 2.8 min · 0.41%
- Mercury-190 20.0 min · 0.41%
- Gold-190 42.8 min · 0.41%
- Platinum-190 4.90×10¹¹ a · 0.41%
- Osmium-186 2.0×10¹⁵ a · 0.41%
- Tungsten-182 stable · 0.41%
Decay notation
| Notation | Name | On the chart | Description |
|---|---|---|---|
| α | alpha decay | Alpha decay is the emission of a helium nucleus (2 protons + 2 neutrons): Z−2, A−4. | |
| β⁻, 2β⁻ | beta-minus decay | In beta-minus decay a neutron turns into a proton and the nucleus emits an electron: Z+1, A unchanged. 2β⁻ is double beta decay. | |
| EC, EC/β⁺ | electron capture / beta-plus decay | A proton turns into a neutron: the nucleus captures a shell electron (EC) or emits a positron (β⁺): Z−1, A unchanged. | |
| p, 2p, 3p | proton emission | Proton emission is the ejection of a proton from the nucleus: Z−1, A−1. 2p, 3p - two, three protons. | |
| n, 2n…4n | neutron emission | Neutron emission is the ejection of a neutron from the nucleus: A−1, Z unchanged. 2n…4n - several neutrons. | |
| ¹⁴C, ²⁴Ne… | cluster emission | Cluster emission is the ejection of a light nucleus, e.g. ¹⁴C, ²⁰O, ²⁴Ne, ²⁸Mg, ³⁴Si. It is a very rare transformation. | |
| IT | isomeric transition | An isomeric transition takes a nucleus from an excited state (an isomer, e.g. Pa-234m) to the ground state, usually emitting a γ photon: Z and A unchanged. | |
| β⁻n, ECp, ECα… | delayed emission | Delayed emission is the emission of a particle (n, p or α) right after β⁻ decay or electron capture. The arrow has the colour of the emitted particle and its label shows the transformation, e.g. “β⁻n 63%”. | |
| SF | spontaneous fission | no arrow | Spontaneous fission is the splitting of a nucleus into two fragments of random masses. There is no single daughter, so the chart shows no arrow - it is listed in the decay branches and in the tile tooltip. |
Data sources
- NNDC Wallet Cards 2023 - Data as of 15 October 2024 - licence: Public domain