Thorium and Actinium Series

TABLE B-1

Thorium (4n) Series

z

Nuclide"2

Half-life

Radiation^

90

232Th (Th)

1.405 x 1010y

a

90

228Th (RdTh)

1.913 y

a, (7)

89

228Ac (MsTh2)

6.15 h

ß", 7

88

228Ra (MsThi)

5.76 y

ß"

88

224Ra (ThX)

3.66 d

a, (7)

86

220Rn (Tn)

55.6s

a

84

216Po (ThA)

0.145s

a

84

212Po (ThC')

298 ns

a

83

212Bi (ThC)

1.009h

a, 35.9%; ß", 64.1%, 7

82

212Pb (ThB)

10.64 h

ß",7

82

208Pb (ThD)

Stable

81

208Tl (ThC'')

3.053m

ß",7

^Symbol used in the early studies of naturally occurring radioactivity is given in parentheses: (MsThj), mesothorium I; (RdTh), radiothorium; (Tn), thoron.

(7) indicates low intensity (1-5%); 7 rays with intensity below 1% are not included. Where both a and are given, branched decay occurs.

thorium and actinium series

90 (Th) 232 89 (Ac) 88 (Ra) 228' 87 (Fr) 86 (Rn) 85 (At) 84 (Po) 83 (Bi) 82 (Pb) 81 (Tl)

FIGURE B-1 Thorium (4k) series. The main sequence is indicated by arrows and a dash.

TABLE B-2

Actinium (4k + 3) Series

z

Nuclide"2

Half-life

Radiation^

92

235U (AcU)

7.04 x 108 y

a, 7

91

231Pa (Pa)

3.28 x 104 y

a, (7)

90

231Th (UY)

1.063 d

ß", 7

90

227Th (RdAc)

18.72 d

a, 7

89

227Ac (Ac)

21.774 y

ß", 98.62%; a,

1.38%

88

223Ra (AcX)

11.435 d

a, 7

87

223Fr (AcK)

21.8m

ß", 99+%, 7; a,

~ 0.005%

86

219Rn (An)

3.96 s

a, 7

85

219At (At)

56s

a, ~ 97%; ß", -

- 3%

85

215At (At)

0.10 ms

a

84

215Po (AcA)

1.780 ms

a, 99%; ß", 3.3

x 10"4%

84

211Po (AcC')

0.516s

a

83

215Bi (Bi)

7.6 m

ß"

TABLE B-2 (continued)

z

Nuclide2

Half-life

Radiation^

83

211Bi (AcC)

2.14m

a, 99.72%, 7

82

211Pb (AcB)

36.1m

ß", 7

82

207Pb (AcD)

Stable

81

207Tl (AcC")

4.77 m

ß"

^Symbol used in the early studies of naturally occurring radioactivity is given in parentheses. (AcU), actinouranium; (RdAc), radioactinium; (An), actinon.

(7) indicates low intensity (1-5%); 7 rays with intensity below 1% are not included. Where both a and are given, branched decay occurs.

92 (U) 235 91 (Pa) 90 (Th) 89 (Ac) 88 (Ra) 87 (Fr) 86 (Rn) 85 (At) 84 (Po) 83 (Bi) 82 (Pb)

FIGURE B-2 Actinium (4« + 3) series. The main sequence is indicated by arrows and a dash.

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