Geology Reference
In-Depth Information
Table 4.1
Natural radioactive decay of
238
U,
232
Th and
40
K
γ
energy (MeV) and %
yield
a
Parent
Mode
Daughter
Half-life
238
U
234
Th
10
9
4.5
×
years
0.09(15) 0.6(7) 0.3(7)
α
234
Th
234
Pa
β
24.1 days
1.01(2) 0.77(1) 0.04(3)
234
Pa
234
U
β
1.18 min
0.05(28)
234
U
230
Th
×
10
5
α
2.6
years
230
Th
226
Ra
8
×
10
4
years
α
226
Ra
222
Rn
1600 years
0.19(4)
α
222
Rn
218
Po
α
3.82 days
218
Po
214
Pb
α
3.05 min
214
Pb
214
Bi
26.8 min
0.35(44) 0.24(11)
0.29(24) 0.05(2)
β
214
Bi
214
Po
β
17.9 min
2.43(2) 2.20(6)
1.76(19) 1.38(7)
1.24(7)
b
214
Po
210
Pb
1.6
×
10
−
4
s
α
210
Pb
210
Bi
19.4 years
β
210
Bi
210
Po
β
5.0 days
0.04(4)
210
Po
206
Pb
α
138.4 days
232
Th
228
Ra
1.4
×
10
10
years
0.06(24)
α
228
Ra
228
Ac
6.7 years
β
228
Ac
228
Th
β
6.1 h
1.64(13) 1.59(12)
0.99(25) 0.97(18)
0.34(11)
b
228
Th
224
Ra
α
1.9 years
224
Ra
220
Rn
3.64 days
α
220
Rn
216
Po
54.5 s
α
216
Po
212
Pb
α
0.16 s
212
Pb
212
Bi
β
10.6 h
0.30(5) 0.24(82)
0.18(1) 0.12(2)
b
212
Bi
212
Po (66%)
β
40 min
1.18(1) 0.83(8)
0.73(10)
208
Tl (34%)
97.3 min
α
212
Po
208
Pb
10
−
6
s
α
0.3
×
208
Tl
208
Pb
β
3.1 min
2.62(100) 0.86(14)
0.58(83) 0.51(25)
b
40
K
40
Ca (89%)
10
9
β
1.47
×
years
10
10
years 1.46(11)
a
Percent yields (shown in parentheses) indicate number of decays, out of each 100, that produce
photons of the energy specified. The total may exceed 100, since some single decay events produce more
than one photon.
b
Photons of numerous additional energies are emitted in these events.
Note also that decay chain branches that involve less than 10% of the parent element are not shown.
40
Ar (11%)
K-capture
1.17
×
