3.2. Neptunium series
T
Fig. 8. Thorium series
a
he
4n + 1 chain of Np-237 are commonly called the "neptunium
series." In this series, only two of the isotopes involved are
found naturally, namely those of 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. [2]
Fig. 9. Neptunium series
a
nuclide |
decay mode |
half-life (a=year) |
energy released, MeV |
product of decay |
249Cf |
α |
351 a |
5.813+.388 |
245Cm |
245Cm |
α |
8500 a |
5.362+.175 |
241Pu |
241Pu |
β− |
14.4 a |
0.021 |
241Am |
241Am |
α |
432.7 a |
5.638 |
237Np |
237Np |
α |
2.14·106 a |
4.959 |
233Pa |
233Pa |
β− |
27.0 d |
0.571 |
233U |
233U |
α |
1.592·105 a |
4.909 |
229Th |
229Th |
α |
7340 a |
5.168 |
225Ra |
225Ra |
β− |
14.9 d |
0.36 |
225Ac |
225Ac |
α |
10.0 d |
5.935 |
221Fr |
221Fr |
α |
4.8 min |
6.3 |
217At |
217At |
α |
32 ms |
7.0 |
213Bi |
213Bi |
β− 97.80% α 2.20% |
46.5 min |
1.423 5.87 |
213Po 209Tl |
213Po |
α |
3.72 μs |
8.536 |
209Pb |
209Tl |
β− |
2.2 min |
3.99 |
209Pb |
209Pb |
β− |
3.25 h |
0.644 |
209Bi |
209Bi |
α |
1.9·1019 a |
3.137 |
205Tl |
205Tl |
. |
stable |
. |
. |
3.3. Radium series (also known as uranium series)
T
he
4n+2 chain of U-238 are 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.