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Appendix B. Selected Radioactive Isotopes

Decay modes are α, β, β+, electron capture (EC) and isomeric transition (IT). EC results in the same daughter nucleus as would β+ decay. IT is a transition from a metastable excited state. Energies for β± decays are the maxima; average energies are roughly one-half the maxima.

Table 1. Selected Radioactive Isotopes
Isotope t1/2 DecayMode(s) Energy(MeV) Percent γ-Ray Energy(MeV) Percent
3H 12.33 y β 0.0186 100%
14C 5730 y β 0.156 100%
13N 9.96 min β+ 1.20 100%
22Na 2.602 y β+ 0.55 90% γ 1.27 100%
32P 14.28 d β 1.71 100%
35S 87.4 d β 0.167 100%
36Cl 3.00 × 105 y β 0.710 100%
40K 1.28 × 109 y β 1.31 89%
43K 22.3 h β 0.827 87% γs 0.373 87%
0.618 87%
45Ca 165 d β 0.257 100%
51Cr 27.70 d EC γ 0.320 10%
52Mn 5.59d β+ 3.69 28% γs 1.33 28%
1.43 28%
52Fe 8.27 h β+ 1.80 43% 0.169 43%
0.378 43%
59Fe 44.6 d βs 0.273 45% γs 1.10 57%
0.466 55% 1.29 43%
60Co 5.271 y β 0.318 100% γs 1.17 100%
1.33 100%
65Zn 244.1 d EC γ 1.12 51%
67Ga 78.3 h EC γs 0.0933 70%
0.185 35%
0.300 19%
others
75Se 118.5 d EC γs 0.121 20%
0.136 65%
0.265 68%
0.280 20%
others
86Rb 18.8 d βs 0.69 9% γ 1.08 9%
1.77 91%
85Sr 64.8 d EC γ 0.514 100%
90Sr 28.8 y β ­ 0.546 100%
90Y 64.1 h β 2.28 100%
99mTc 6.02 h IT γ 0.142 100%
113mIn 99.5 min IT γ 0.159 100%
123I 13.0 h EC γ 0.159 ≈100%
131I 8.040 d βs 0.248 7% γs 0.364 85%
0.607 93% others
others
129Cs 32.3 h EC γs 0.0400 35%
0.372 32%
0.411 25%
others
137Cs 30.17 y βs 0.511 95% γ 0.662 95%
1.17 5%
140Ba 12.79 d β 1.035 ≈100% γs 0.030 25%
0.044 65%
0.537 24%
others
198Au 2.696 d β 1.161 ≈100% γ 0.412 ≈100%
197Hg 64.1 h EC γ 0.0733 100%
210Po 138.38 d α 5.41 100%
226Ra 1.60 × 103 y αs 4.68 5% γ 0.186 100%
4.87 95%
235U 7.038 × 108 y α 4.68 ≈100% γs numerous <0.400%
238U 4.468 × 109 y αs 4.22 23% γ 0.050 23%
4.27 77%
237Np 2.14 × 106 y αs numerous γs numerous <0.250%
4.96 (max.)
239Pu 2.41 × 104 y αs 5.19 11% γs 7.5 × 10−5 73%
5.23 15% 0.0133 15%
5.24 73% 0.052 10%
others
243Am 7.37 × 103 y αs Max. 5.44 γs 0.075
5.37 88% others
5.32 11%
others


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