| Nuclear physics |
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High-energy processes |
Innuclear science adecay chain refers to the predictable series ofradioactive disintegrations undergone by the nuclei of certain unstable chemical elements.
Radioactive isotopes do not usually decay directly tostable isotopes, but rather into another radioisotope. The isotope produced by this radioactive emission then decays into another, often radioactive isotope. This chain of decays always terminates in astable isotope, whose nucleus no longer has the surplus of energy necessary to produce another emission of radiation. Such stable isotopes are then said to have reached theirground states.
The stages or steps in a decay chain are referred to by their relationship to previous or subsequent stages. Hence, aparent isotope is one that undergoes decay to form adaughter isotope. For example element 92,uranium, has an isotope with 144 neutrons (236U) and it decays into an isotope of element 90,thorium, with 142 neutrons (232Th). The daughter isotope may be stable or it may itself decay to form another daughter isotope.232Th does this when it decays intoradium-228. The daughter of a daughter isotope, such as228Ra, is sometimes called agranddaughter isotope.228Ra in turn undergoes a further eight decays andtransmutations until a stable isotope,208Pb, is produced, terminating the decay chain of236U.
The time required for an atom of a parent isotope to decay into its daughter is fundamentally unpredictable and varies widely. For individual nuclei the process isnot known to have determinable causes and the time at which it occurs is thereforecompletely random. The only prediction that can be made is statistical and expresses an average rate of decay. This rate can be represented by adjusting the curve of a decayingexponential distribution with adecay constant (λ) particular to the isotope. On this understanding the radioactive decay of an initial population of unstable atoms over timet follows the curve given bye−λt.
One of the most important properties of any radioactive material follows from this analysis, itshalf-life. This refers to the time required for half of a given number of radioactive atoms to decay and is inversely related to the isotope's decay constant,λ. Half-lives have been determined in laboratories for many radionuclides, and canrange from nearly instantaneous—hydrogen-5 decays in lesstime than it takes for a photon to go from one end of its nucleus to the other—to fourteenorders of magnitude longer than theage of the universe:tellurium-128 has a half-life of2.2×1024 years.
TheBateman equation predicts the relative quantities of all the isotopes that compose a given decay chain once that decay chain has proceeded long enough for some of its daughter products to have reached the stable (i.e., nonradioactive) end of the chain. A decay chain that has reached this state, which may require billions of years, is said to be inequilibrium. A sample of radioactive material inequilibrium produces a steady and steadily decreasing quantity of radioactivity as the isotopes that compose it traverse the decay chain. On the other hand, if a sample of radioactive material has been isotopically enriched, meaning that a radioisotope is present in larger quantities than would exist if a decay chain were the only cause of its presence, that sample is said to beout of equilibrium. An unintuitive consequence of this disequilibrium is that a sample ofenriched material may occasionally increase in radioactivity as daughter products that are more highly radioactive than their parents accumulate. Bothenriched anddepleted uranium provide examples of this phenomenon.
The chemical elements came into being in two phases. The first commenced shortly after theBig Bang. From ten seconds to 20 minutes after the beginning of the universe theearliest condensation of light atoms was responsible for the manufacture of the four lightest elements. The vast majority of this primordial production consisted of the three lightest isotopes ofhydrogen—protium,deuterium andtritium—and two of the nine known isotopes ofhelium—helium-3 andhelium-4. Trace amounts oflithium-7 andberyllium-7 were likely also produced.
So far as is known, all heavier elements came into being starting around 100 million years later, in a second phase ofnucleosynthesis that commenced with the birth of thefirst stars.[1] The nuclear furnaces that power stellar evolution were necessary to create large quantities of all elements heavier than helium, and ther- ands-processes of neutron capture that occur in stellar cores are thought to have created all such elements up toiron andnickel (atomic numbers 26 and 28). Theextreme conditions that attendsupernovae explosions are capable of creating the elements betweenoxygen andrubidium (i.e., atomic numbers 8 through 37). The creation of heavier elements, including those without stable isotopes—all elements with atomic numbers greater than lead's, 82—appears to rely on r-process nucleosynthesis operating amid the immense concentrations of free neutrons released duringneutron star mergers.
Most of the isotopes of each chemical element present in the Earth today were formed by such processes no later than the time ofour planet's condensation from the solarprotoplanetary disc, around 4.5 billion years ago. The exceptions to these so-calledprimordial elements are those that have resulted from the radioactive disintegration of unstable parent nuclei as they progress down one of several decay chains, each of which terminates with the production of one of the 251 stable isotopes known to exist. Aside from cosmic or stellar nucleosynthesis, and decay chains the only other ways of producing a chemical element rely onatomic weapons, nuclear reactors (natural ormanmade) or the laborious atom-by-atomassembly of nuclei withparticle accelerators.
Unstable isotopes decay to their daughter products (which may sometimes be even more unstable) at a given rate; eventually, often after a series of decays, a stable isotope is reached: there are 251 stable isotopes in the universe. In stable isotopes, light elements typically have a lower ratio of neutrons to protons in their nucleus than heavier elements. Light elements such ashelium-4 have close to a 1:1 neutron:proton ratio. The heaviest elements such as uranium have close to 1.5 neutrons per proton (e.g. 1.587 inuranium-238). No nuclide heavier than lead-208 is stable; these heavier elements have to shed mass to achieve stability, mostly byalpha decay. The other common way for isotopes with a high neutron to proton ratio (n/p) to decay isbeta decay, in which the nuclide changes elemental identity while keeping the same mass number and lowering its n/p ratio. For some isotopes with a relatively low n/p ratio, there is aninverse beta decay, by which a proton is transformed into a neutron, thus moving towards a stable isotope; however, since fission almost always produces products which are neutron heavy,positron emission orelectron capture are rare compared to electron emission. There are many relatively short beta decay chains, at least two (a heavy, beta decay and a light,positron decay) for every discrete weight up to around 207 and some beyond, but for the higher mass elements (isotopes heavier than lead) there are only four pathways which encompass all decay chains.[citation needed] This is because there are just two main decay methods:alpha radiation, which reduces the mass number by 4, and beta, which leaves it unchanged. The four paths are termed 4n, 4n + 1, 4n + 2, and 4n + 3; the remainder from dividing the atomic mass by four gives the chain the isotope will follow in its decay. There are other decay modes, but they invariably occur at a lower probability than alpha or beta decay. (It should not be supposed that these chains have no branches: the diagram below shows a few branches of chains, and in reality there are many more, because there are many more isotopes possible than are shown in the diagram.) For example, the third atom ofnihonium-278 synthesised underwent six alpha decays down tomendelevium-254, followed by anelectron capture (a form of beta decay) tofermium-254, and then a seventh alpha tocalifornium-250,[2] upon which it would have followed the 4n + 2 chain (radium series) as given in this article. However, the heaviestsuperheavy nuclides synthesised do not reach the four decay chains, because they reach aspontaneously fissioning nuclide after a few alpha decays that terminates the chain: this is what happened to the first two atoms of nihonium-278 synthesised,[3][4] as well as to all heavier nuclides produced.
Three of those chains have a long-lived isotope (or nuclide) near the top; this long-lived nuclide is a bottleneck in the process through which the chain flows very slowly, and keeps the chain below them "alive" with flow. The three long-lived nuclides are uranium-238 (half-life 4.463 billion years), uranium-235 (half-life 704 million years) and thorium-232 (half-life 14.1 billion years). The fourth chain has no such long-lasting bottleneck nuclide near the top, so that chain has long since decayed down to the last before the end: bismuth-209. This nuclide was long thought to be stable, but in 2003 it was found to be unstable, with a very long half-life of 20.1 billion billion years;[5] it is the last step in the chain before stable thallium-205. Because this bottleneck is so long-lived, very small quantities of the final decay product have been produced, and for most practical purposes bismuth-209 is the final decay product.
In the past, during the first few million years of the history of the Solar System, there were more unstable high-mass nuclides in existence, and the four chains were longer, as they included nuclides that have since decayed away. Notably,244Pu,237Np, and247Cm have half-lives over a million years and would have then been bottlenecks higher in the 4n, 4n+1, and 4n+3 chains respectively[6] -244Pu and247Cm have been identified as having been present. (There is no nuclide with a half-life over a million years above238U in the 4n+2 chain.) Today some of these formerly extinct isotopes are again in existence as they have been manufactured. Thus they again take their places in the chain: plutonium-239, used in nuclear weapons, is the major example, decaying to uranium-235 via alpha emission with a half-life 24,500 years. There has also been large-scale production of neptunium-237, resurrecting the extinct fourth chain.[7] The tables below hence start the four decay chains at isotopes ofcalifornium with mass numbers from 249 to 252.
| Name of series | Thorium | Neptunium | Uranium | Actinium |
| Mass numbers | 4n | 4n+1 | 4n+2 | 4n+3 |
| Long-lived nuclide | 232Th (244Pu) | 209Bi (237Np) | 238U | 235U (247Cm) |
| Half-life (billions of years) | 14.1 (0.0813) | 20100000000 (0.002144) | 4.463 | 0.704 (0.0156) |
| End of chain | 208Pb | 205Tl | 206Pb | 207Pb |
These four chains are summarised in the chart in the following section.
The four most common modes of radioactive decay are: alpha decay, beta decay,inverse beta decay (considered as both positron emission and electron capture), andisomeric transition. Of these decay processes, only alpha decay (fission of ahelium-4 nucleus) changes theatomic mass number (A) of the nucleus, and always decreases it by four. Because of this, almost any decay will result in a nucleus whose atomic mass number has the sameresidue mod 4. This divides the list of nuclides into four classes, each of which forms a main decay chain.
Three of these are readily observed in nature, commonly called the thorium series, theradium or uranium series, and theactinium series, representing three of these four classes, and ending in three different, stable isotopes oflead. The mass number of every isotope in the chain can be represented asA = 4n,A = 4n + 2, or A = 4n + 3, respectively. The long-lived starting isotopes of these three isotopes, respectivelythorium-232,uranium-238, anduranium-235, have existed since the formation of the Earth, ignoring the artificial isotopes and their decays created since the 1940s.
Due to the relatively shorthalf-life of its starting isotopeneptunium-237 (2.144 million years), the fourth chain, theneptunium series withA = 4n + 1, is already extinct in nature, except for the final rate-limiting step, decay ofbismuth-209. Traces of237Np and its decay products do occur in nature, however, as a result of neutron reactions in uranium ore; neutron capture by natural thorium to give233U is also possible.[8] The ending isotope of this chain is now known to bethallium-205. Some older sources give the final isotope as bismuth-209, but in 2003 it was discovered that it is very slightly radioactive, with a half-life of2.01×1019 years.[9]
There are also non-transuranic decay chains of unstable isotopes of light elements, for example those ofmagnesium-28 andchlorine-39. On Earth, most of the starting isotopes of these chains before 1945 were generated bycosmic radiation. Since 1945, the testing and use of nuclear weapons has also released numerous radioactivefission products. Almost all such isotopes decay by either β− or β+ decay modes, changing from one element to another at the same atomic mass. The later daughter products in such a chain, being closer to beta-stability, generally have the longer half-lives.
| Actinides[10] bydecay chain | Half-life range (a) | Fission products of235U byyield[11] | ||||||
|---|---|---|---|---|---|---|---|---|
| 4n (Thorium) | 4n + 1 (Neptunium) | 4n + 2 (Radium) | 4n + 3 (Actinium) | 4.5–7% | 0.04–1.25% | <0.001% | ||
| 228Ra№ | 4–6 a | 155Euþ | ||||||
| 248Bk[12] | > 9 a | |||||||
| 244Cmƒ | 241Puƒ | 250Cf | 227Ac№ | 10–29 a | 90Sr | 85Kr | 113mCdþ | |
| 232Uƒ | 238Puƒ | 243Cmƒ | 29–97 a | 137Cs | 151Smþ | 121mSn | ||
| 249Cfƒ | 242mAmƒ | 141–351 a | No fission products have ahalf-life | |||||
| 241Amƒ | 251Cfƒ[13] | 430–900 a | ||||||
| 226Ra№ | 247Bk | 1.3–1.6 ka | ||||||
| 240Pu | 229Th | 246Cmƒ | 243Amƒ | 4.7–7.4 ka | ||||
| 245Cmƒ | 250Cm | 8.3–8.5 ka | ||||||
| 239Puƒ | 24.1 ka | |||||||
| 230Th№ | 231Pa№ | 32–76 ka | ||||||
| 236Npƒ | 233Uƒ | 234U№ | 150–250 ka | 99Tc₡ | 126Sn | |||
| 248Cm | 242Pu | 327–375 ka | 79Se₡ | |||||
| 1.33 Ma | 135Cs₡ | |||||||
| 237Npƒ | 1.61–6.5 Ma | 93Zr | 107Pd | |||||
| 236U | 247Cmƒ | 15–24 Ma | 129I₡ | |||||
| 244Pu | 80 Ma | ... nor beyond 15.7 Ma[14] | ||||||
| 232Th№ | 238U№ | 235Uƒ№ | 0.7–14.1 Ga | |||||
| ||||||||
In the four tables below, very minor branches of decay (branching probability less than one in a million) are omitted.Spontaneous fission is also omitted, though larger than this for the heaviest even nuclei and detectable down to thorium. All nuclear data is taken from[9] unless otherwise noted. The historical names of isotopes are recorded in.[15]
The energy release includes the total kinetic energy of all the emitted particles (electrons,alpha particles,gamma quanta,neutrinos,Auger electrons andX-rays) and the recoiling decay product nucleus; this corresponds to that calculated from atomic masses. The letter 'a' represents a year (from the Latinannus).
In the tables (except for the neptunium series), the historical names of the naturally occurring nuclides are also given. Such names were used at the time when the decay chains were first discovered and investigated; the system listed was only finalized in the 1920s but it would be too confusing to give earlier names also. From these historical names one can thus find the modern isotopic designation.
The three primordial chains given below—thorium, uranium/radium (from uranium-238), and actinium (from uranium-235)—each ends with its own specific lead isotope (lead-208, lead-206, and lead-207 respectively). All the lead isotopes are stable and are also present in nature asprimordial nuclides, so their excess amounts in comparison with lead-204 (which has only a primordial origin) are required for accurateuranium–lead dating of rocks. Correlating more than one results inlead-lead dating, capable of even greater accuracy.
The 4n chain of thorium-232 is commonly called the "thorium series" or "thorium cascade". The series terminates with lead-208, 6alpha decays and 4beta decays from thorium.
Plutonium-244 (which appears several steps above thorium-232) was present in the early Solar System,[6] and is just long-lived enough that it should still survive in trace quantities today,[16] though it probably has not been detected.[17]
The total energy released from thorium-232 to lead-208, including the energy lost to neutrinos, is 42.65 MeV; from californium-252, 71.11 MeV. That last is the largest of the four chains, unsurprisingly for the shell-stability of the product.
| Nuclide | Historic names | Decay mode | Half-life (a = years) | Energy released MeV | Decay product | |
|---|---|---|---|---|---|---|
| Short | Long | |||||
| 252Cf | α | 2.645 a | 6.217 | 248Cm | ||
| 248Cm | α | 3.48×105 a | 5.162 | 244Pu | ||
| 244Pu | α | 8.13×107 a | 4.666 | 240U | ||
| 240U | β− | 14.1 h | 0.382 | 240mNp[18] | ||
| 240mNp | IT 0.12% β− 99.88% | 7.22 min | 0.018 2.209 | 240Np 240Pu | ||
| 240Np | β− | 61.9 min | 2.191 | 240Pu | ||
| 240Pu | α | 6561 a | 5.256 | 236U | ||
| 236U | Thoruranium[19] | α | 2.342×107 a | 4.573 | 232Th | |
| 232Th | Th | Thorium | α | 1.40×1010 a | 4.082 | 228Ra |
| 228Ra | MsTh1 | Mesothorium 1 | β− | 5.75 a | 0.046 | 228Ac |
| 228Ac | MsTh2 | Mesothorium 2 | β− | 6.15 h | 2.123 | 228Th |
| 228Th | RdTh | Radiothorium | α | 1.9125 a | 5.520 | 224Ra |
| 224Ra | ThX | Thorium X | α | 3.632 d | 5.789 | 220Rn |
| 220Rn | Tn | Thoron, Thorium Emanation | α | 55.6 s | 6.405 | 216Po |
| 216Po | ThA | Thorium A | α | 0.144 s | 6.906 | 212Pb |
| 212Pb | ThB | Thorium B | β− | 10.627 h | 0.569 | 212Bi |
| 212Bi | ThC | Thorium C | β− 64.06% α 35.94% | 60.55 min | 2.252 6.207 | 212Po 208Tl |
| 212Po | ThC′ | Thorium C′ | α | 294.4 ns | 8.954 | 208Pb |
| 208Tl | ThC″ | Thorium C″ | β− | 3.053 min | 4.999 | 208Pb |
| 208Pb | ThD | Thorium D | stable | |||
.svg)
The 4n+1 chain of neptunium-237 is commonly called the "neptunium series" or "neptunium cascade". In this series, only two of the isotopes involved are found naturally in significant quantities, namely the final two: bismuth-209 and thallium-205. Some of the other isotopes have been detected in nature, originating from trace quantities of237Np produced by the (n,2n)knockout reaction in primordial238U.[8]
Since this series was only discovered and studied in 1947–1948,[20] its nuclides were never given historic names. Uniquely among the four, this decay chain has an isotope of radon only produced in a rare branch (not shown in the illustration) but not in the main decay sequence; thus, radon from this decay chain will hardly migrate through rock. Also uniquely, it ends in thallium (or, practically speaking, bismuth) rather than lead. This series terminates with the stable isotope thallium-205, 8alpha decays and 4beta decays from neptunium.
The total energy released from neptunium-237 to thallium-205, including the energy lost toneutrinos, is 49.29 MeV; from californium-249, 66.87 MeV. As the energy of the final step from bismuth to thallium, though known, will not be available until the inconceivable future, it may be better to quote the figures 46.16 MeV and 63.73 MeV to bismuth-209.
| Nuclide | Decay mode | Half-life (a = years) | Energy released MeV | Decay product |
|---|---|---|---|---|
| 249Cf | α | 351 a | 6.293 | 245Cm |
| 245Cm | α | 8250 a | 5.624 | 241Pu |
| 241Pu | β− 99.9975% α 0.0025% | 14.33 a | 0.021 5.140 | 241Am 237U |
| 241Am | α | 432.6 a | 5.638 | 237Np |
| 237U | β− | 6.752 d | 0.518 | 237Np |
| 237Np | α | 2.144×106 a | 4.957 | 233Pa |
| 233Pa | β− | 26.98 d | 0.570 | 233U |
| 233U | α | 1.592×105 a | 4.909 | 229Th |
| 229Th | α | 7920 a | 5.168 | 225Ra |
| 225Ra | β− 99.9974% α 0.0026%[21][a] | 14.8 d | 0.356 5.097 | 225Ac 221Rn |
| 225Ac | α | 9.919 d | 5.935 | 221Fr |
| 221Rn | β− 78% α 22% | 25.7 min | 1.194 6.163 | 221Fr 217Po |
| 221Fr | α 99.9952% β− 0.0048% | 4.801 min | 6.457 0.313 | 217At 221Ra |
| 221Ra | α | 25 s | 6.880 | 217Rn |
| 217Po | α 97.5% β− 2.5% | 1.53 s | 6.662 1.488 | 213Pb 217At |
| 217At | α 99.992% β− 0.008% | 32.6 ms | 7.202 0.736 | 213Bi 217Rn |
| 217Rn | α | 590 μs | 7.888 | 213Po |
| 213Pb | β− | 10.2 min | 2.028 | 213Bi |
| 213Bi | β− 97.91% α 2.09% | 45.6 min | 1.422 5.988 | 213Po 209Tl |
| 213Po | α | 3.705 μs | 8.536 | 209Pb |
| 209Tl | β− | 2.162 min | 3.970 | 209Pb |
| 209Pb | β− | 3.235 h | 0.644 | 209Bi |
| 209Bi | α | 2.01×1019 a | 3.137 | 205Tl |
| 205Tl | stable |
.svg)
The 4n+2 chain of uranium-238 is called the "uranium series" or "radium series", the latter from the first member known when it was named, radium-226. The series terminates with lead-206, 8alpha decays and 6beta decays from uranium.
The total energy released from uranium-238 to lead-206, including the energy lost to neutrinos, is 51.69 MeV; from californium-250, 68.28 MeV.
| Nuclide | Historic names | Decay mode | Half-life (a = years) | Energy released MeV | Decay product | |
|---|---|---|---|---|---|---|
| Short | Long | |||||
| 250Cf | α | 13.08 a | 6.128 | 246Cm | ||
| 246Cm | α | 4760 a | 5.475 | 242Pu | ||
| 242Pu | α | 3.75×105 a | 4.984 | 238U | ||
| 238U | UI | Uranium I | α | 4.463×109 a | 4.270 | 234Th |
| 234Th | UX1 | Uranium X1 | β− | 24.11 d | 0.195 | 234mPa[18] |
| 234mPa | UX2, Bv | Uranium X2 Brevium | IT 0.16% β− 99.84% | 1.16 min | 0.079 2.273 | 234Pa 234U |
| 234Pa | UZ | Uranium Z | β− | 6.70 h | 2.194 | 234U |
| 234U | UII | Uranium II | α | 2.455×105 a | 4.858 | 230Th |
| 230Th | Io | Ionium | α | 7.54×104 a | 4.770 | 226Ra |
| 226Ra | Ra | Radium | α | 1600 a | 4.871 | 222Rn |
| 222Rn | Rn | Radon, Radium Emanation | α | 3.8215 d | 5.590 | 218Po |
| 218Po | RaA | Radium A | α 99.98% β− 0.02% | 3.097 min | 6.115 0.257 | 214Pb 218At |
| 218At | α 100% β− | 1.28 s | 6.876 2.883 | 214Bi 218Rn | ||
| 218Rn | α | 33.75 ms | 7.262 | 214Po | ||
| 214Pb | RaB | Radium B | β− | 27.06 min | 1.018 | 214Bi |
| 214Bi | RaC | Radium C | β− 99.979% α 0.021% | 19.9 min | 3.269 5.621 | 214Po 210Tl |
| 214Po | RaC' | Radium C' | α | 163.5 μs | 7.833 | 210Pb |
| 210Tl | RaC" | Radium C" | β− β−n 0.009% | 1.30 min | 5.481 0.296 | 210Pb 209Pb (inneptunium series) |
| 210Pb | RaD | Radium D | β− α 1.9×10−6% | 22.2 a | 0.0635 3.793 | 210Bi 206Hg |
| 210Bi | RaE | Radium E | β− α 1.32×10−4% | 5.012 d | 1.161 5.035 | 210Po 206Tl |
| 210Po | RaF | Radium F | α | 138.376 d | 5.407 | 206Pb |
| 206Hg | β− | 8.32 min | 1.307 | 206Tl | ||
| 206Tl | RaE" | Radium E" | β− | 4.20 min | 1.532 | 206Pb |
| 206Pb | RaG | Radium G | stable | |||
The 4n+3 chain ofuranium-235 is commonly called the "actinium series" or "actinium cascade", from the first member known when it was named, actinium-227. This series terminates with lead-207, 7alpha decays and 4beta decays from uranium.
In the early Solar System, this chain went back to247Cm. This manifests itself today as variations in235U/238U ratios, sincecurium and uranium have noticeably different chemistries and therefore partitioned differently.[6][22]
The total energy released from uranium-235 to lead-207, including the energy lost to neutrinos, is 46.40 MeV; from californium-251, 69.91 MeV.
| Nuclide | Historic name | Decay mode | Half-life (a = years) | Energy released MeV | Decay product | |
|---|---|---|---|---|---|---|
| Short | Long | |||||
| 251Cf | α | 900 a | 6.177 | 247Cm | ||
| 247Cm | α | 1.56×107 a | 5.353 | 243Pu | ||
| 243Pu | β− | 4.955 h | 0.578 | 243Am | ||
| 243Am | α | 7350 a | 5.439 | 239Np | ||
| 239Np | β- | 2.356 d | 0.723 | 239Pu | ||
| 239Pu | α | 2.411×104 a | 5.244 | 235U | ||
| 235U | AcU | Actino-uranium | α | 7.04×108 a | 4.678 | 231Th |
| 231Th | UY | Uranium Y | β− | 25.52 h | 0.391 | 231Pa |
| 231Pa | Pa | Protoactinium | α | 3.27×104 a | 5.150 | 227Ac |
| 227Ac | Ac | Actinium | β− 98.62% α 1.38% | 21.772 a | 0.045 5.042 | 227Th 223Fr |
| 227Th | RdAc | Radioactinium | α | 18.693 d | 6.147 | 223Ra |
| 223Fr | AcK | Actinium K | β− 99.994% α 0.006% | 22.00 min | 1.149 5.561 | 223Ra 219At |
| 223Ra | AcX | Actinium X | α | 11.435 d | 5.979 | 219Rn |
| 219At | α 93.6% β− 6.4% | 56 s | 6.342 1.567 | 215Bi 219Rn | ||
| 219Rn | An | Actinon, Actinium Emanation | α | 3.96 s | 6.946 | 215Po |
| 215Bi | β− | 7.6 min | 2.171 | 215Po | ||
| 215Po | AcA | Actinium A | α β− 2.3×10−4% | 1.781 ms | 7.526 0.715 | 211Pb 215At |
| 215At | α | 37 μs | 8.177 | 211Bi | ||
| 211Pb | AcB | Actinium B | β− | 36.16 min | 1.366 | 211Bi |
| 211Bi | AcC | Actinium C | α 99.724% β− 0.276% | 2.14 min | 6.750 0.573 | 207Tl 211Po |
| 211Po | AcC' | Actinium C' | α | 516 ms | 7.595 | 207Pb |
| 207Tl | AcC" | Actinium C" | β− | 4.77 min | 1.418 | 207Pb |
| 207Pb | AcD | Actinium D | stable | |||
{{cite web}}: CS1 maint: multiple names: authors list (link)
IAEA – Live Chart of Nuclides (with decay chains)