Decay Chains
Information scientists can use known decay chains to infer
the age of undated nuclear materials, such as smuggled nuclear materials that are interdicted by authorities.
We chose a handful of isotopes,
based on their significance to nuclear forensics, and we display the decay chain
of those isotopes below. The selected isotopes are isotopes of elements in
the Actinide Series on the Periodic Table of Elements. The element numbers range from 90 to 96 -
Thorium (no. 90), Proactinium (no. 91), Uranium (no. 92), Neptunium (no. 93), Plutonium (no. 94), Americium (no. 95),
and Curium (no. 96).
This table summarizes the relationship between the selected isotopes, their elements, and the isotopes' decay chains.
| Selected Isotope |
Element |
Element No. |
Decay Chain Description |
|---|---|---|---|
| Th-232 | Thorium | 90 | The Thorium Series |
| Pa-231 | Proactinium | 91 | A child in the Actinium Series |
| U-235 | Uranium | 92 | The Actinium Series |
| U-238 | Uranium | 92 | The Radium, or Uranium, Series |
| Np-237 | Neptunium | 93 | The Neptunium Series |
| Pu-239 | Plutonium | 94 | A parent of the Actinium Series |
| Am-241 | Americium | 95 | A parent of the Neptunium Series |
| Cm-241 | Curium | 96 | A (distant) parent of the Actinium Series |
Decay chain description source: Modified from Wikipedia's "decay chain" entry.
Decay Chain of Isotope Th-232
The 4n chain of Th-232 is commonly called the Thorium Series.
Beginning with naturally occurring thorium-232, this series includes the
following elements: actinium, bismuth, lead, polonium, radium and radon.
All are present, at least transiently, in any natural thorium-containing
sample, whether metal, compound, or mineral. The series terminates with lead-208.
The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.
Image source: Thorium SVG image
by Wikipedia contributor BatesIsBack.
Decay Chain of Isotope Pa-231
Pa-231 is a child in the Actinium Series.
Beginning with the naturally-occurring isotope U-235, this decay series includes the following elements:
Actinium, astatine, bismuth, francium, lead, polonium, protactinium, radium, radon, thallium, and thorium.
All are present, at least transiently, in any sample containing uranium-235, whether metal, compound, ore, or mineral.
This series terminates with the stable isotope lead-207.
The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.
Image source: Modified by Chloe Reynolds
based on the Thorium SVG image
by Wikipedia contributor BatesIsBack.
Decay Chain of Isotope U-235
The 4n+3 chain of uranium-235 is commonly called the "actinium series".
Beginning with the naturally-occurring isotope U-235, this decay series
includes the following elements: Actinium, astatine, bismuth, francium, lead,
polonium, protactinium, radium, radon, thallium, and thorium. All are present,
at least transiently, in any sample containing uranium-235, whether metal,
compound, ore, or mineral. This series terminates with the stable isotope lead-207.
The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.
Image source: Modified by Chloe Reynolds
based on the Thorium SVG image
by Wikipedia contributor BatesIsBack.
Decay Chain of Isotope U-238
The 4n+2 chain of U-238 is commonly called the Radium Series (sometimes Uranium Series).
Beginning with naturally occurring uranium-238, this series includes the following elements:
astatine, bismuth, lead, polonium, protactinium, radium, radon, thallium and thorium.
All are present, at least transiently, in any natural uranium-containing sample,
whether metal, compound, or mineral. The series terminates with lead-206.
The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia contributor Tosaka.
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Modified by Chloe Reynolds
based on the Thorium SVG image
by Wikipedia contributor BatesIsBack
and the Radium Series png image
by Wikipedia contributor Tosaka.
Decay Chain of Isotope Np-237
The 4n + 1 chain of Np-237 is commonly called the Neptunium Series.
In this series, only two of the elements are found naturally, bismuth and thallium.
A smoke detector containing an americium-241 ionization chamber accumulates a significant
amount of neptunium-237 as its americium decays; the following elements are also present
in it, at least transiently, as decay products of the neptunium: actinium, astatine, bismuth,
francium, lead, polonium, protactinium, radium, thallium, thorium and uranium.
Since this series was only studied more recently, its nuclides do not have historic names.
The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.
Modified by Chloe Reynolds
based on the Neptunium SVG image
by Wikipedia contributor BatesIsBack.
Decay Chain of Isotope Pu-239
Pu-239 decays into U-235, which is the start of the Actinium Series.
Beginning with the isotope U-235, this decay series includes the following elements:
Actinium, astatine, bismuth, francium, lead, polonium, protactinium, radium, radon, thallium, and thorium.
All are present, at least transiently, in any sample containing uranium-235, whether metal, compound, ore, or mineral.
This series terminates with the stable isotope lead-207.
The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.
Image source: Modified by Chloe Reynolds
based on the Thorium SVG image
by Wikipedia contributor BatesIsBack.
Decay Chain of Isotope Am-241
Am-241 decays into Np-237 and then follows the Neptunium Series decay chain.
The following elements are also present, at least transiently, as decay products of the
neptunium: actinium, astatine, bismuth, francium, lead, polonium, protactinium, radium,
thallium, thorium, and uranium.
The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wikipedia.
Modified by Chloe Reynolds
based on the Neptunium SVG image
by Wikipedia contributor BatesIsBack.
Decay Chain of Isotope Cm-247
Cm-247 decays, after five decay generations, into U-235. Then it follows the Actinium Series decay chain.
The Actinium decay series includes the following elements:
Actinium, astatine, bismuth, francium, lead, polonium, protactinium, radium, radon, thallium, and thorium.
All are present, at least transiently, in any sample containing uranium-235, whether metal, compound, ore, or mineral.
This series terminates with the stable isotope lead-207.
The details in decay chain (symbol, atomic mass, number of protons, half-life, decay children) are taken from Wolfram Alpha.
Image source: Modified by Chloe Reynolds
based on the Thorium SVG image
by Wikipedia contributor BatesIsBack.