Chapter 16: Selected Radioactive Isotopes
Decay modes are \(\alpha\), \(\beta^{-}\), \(\beta^{+}\), electron capture (EC) and isomeric transition (IT). EC results in the same daughter nucleus as would \(\beta^{+}\) decay. IT is a transition from a metastable excited state. Energies for \(\beta^{\pm}\) decays are the maxima; average energies are roughly one-half the maxima.
| Isotope | t 1/2 | DecayMode(s) | Energy(MeV) | Percent | \(\gamma\)-Ray Energy(MeV) | Percent | |
|---|---|---|---|---|---|---|---|
| \({ }^{3} \mathrm{H}\) | 12.33 y | \(\beta^{-}\) | 0.0186 | 100% | |||
| \({ }^{14} \mathrm{C}\) | 5730 y | \(\beta^{-}\) | 0.156 | 100% | |||
| \({ }^{13} \mathrm{N}\) | 9.96 min | \(\beta^{+}\) | 1.20 | 100% | |||
| \({ }^{22} \mathrm{Na}\) | 2.602 y | \(\beta^{+}\) | 0.55 | 90% | \(\gamma\) | 1.27 | 100% |
| \({ }^{32} \mathrm{P}\) | 14.28 d | \(\beta^{-}\) | 1.71 | 100% | |||
| \({ }^{35} \mathrm{S}\) | 87.4 d | \(\beta^{-}\) | 0.167 | 100% | |||
| \({ }^{36} \mathrm{Cl}\) | \(3.00 \times 10^{5} \mathrm{y}\) | \(\beta^{-}\) | 0.710 | 100% | |||
| \({ }^{40} \mathrm{K}\) | \(1.28 \times 10^{9} \mathrm{y}\) | \(\beta^{-}\) | 1.31 | 89% | |||
| \({ }^{43} \mathrm{K}\) | 22.3 h | \(\beta^{-}\) | 0.827 | 87% | \(\gamma \mathrm{s}\) | 0.373 | 87% |
| 0.618 | 87% | ||||||
| \({ }^{45} \mathrm{Ca}\) | 165 d | \(\beta^{-}\) | 0.257 | 100% | |||
| \({ }^{51} \mathrm{Cr}\) | 27.70 d | EC | \(\gamma\) | 0.320 | 10% | ||
| \({ }^{52} \mathrm{Mn}\) | 5.59d | \(\beta^{+}\) | 3.69 | 28% | \(\gamma \mathrm{s}\) | 1.33 | 28% |
| 1.43 | 28% | ||||||
| \({ }^{52} \mathrm{Fe}\) | 8.27 h | \(\beta^{+}\) | 1.80 | 43% | 0.169 | 43% | |
| 0.378 | 43% | ||||||
| \({ }^{59} \mathrm{Fe}\) | 44.6 d | \(\beta^{-} \mathrm{s}\) | 0.273 | 45% | \(\gamma \mathrm{s}\) | 1.10 | 57% |
| 0.466 | 55% | 1.29 | 43% | ||||
| \({ }^{60} \mathrm{Co}\) | 5.271 y | \(\beta^{-}\) | 0.318 | 100% | \(\gamma \mathrm{s}\) | 1.17 | 100% |
| 1.33 | 100% | ||||||
| \({ }^{65} \mathrm{Zn}\) | 244.1 d | EC | \(\gamma\) | 1.12 | 51% | ||
| \({ }^{67} \mathrm{Ga}\) | 78.3 h | EC | \(\gamma \mathrm{s}\) | 0.0933 | 70% | ||
| 0.185 | 35% | ||||||
| 0.300 | 19% | ||||||
| others | |||||||
| \({ }^{75} \mathrm{Se}\) | 118.5 d | EC | \(\gamma \mathrm{s}\) | 0.121 | 20% | ||
| 0.136 | 65% | ||||||
| 0.265 | 68% | ||||||
| 0.280 | 20% | ||||||
| others | |||||||
| \({ }^{86} \mathrm{Rb}\) | 18.8 d | \(\beta^{-} \mathrm{s}\) | 0.69 | 9% | \(\gamma\) | 1.08 | 9% |
| 1.77 | 91% | ||||||
| \({ }^{85} \mathrm{Sr}\) | 64.8 d | EC | \(\gamma\) | 0.514 | 100% | ||
| \({ }^{90} \mathrm{Sr}\) | 28.8 y | \(\beta^{-}\) | 0.546 | 100% | |||
| \({ }^{90} \mathrm{Y}\) | 64.1 h | \(\beta^{-}\) | 2.28 | 100% | |||
| \({ }^{99 \mathrm{m}} \mathrm{Tc}\) | 6.02 h | IT | \(\gamma\) | 0.142 | 100% | ||
| \({ }^{113 \mathrm{m}} \mathrm{In}\) | 99.5 min | IT | \(\gamma\) | 0.392 | 100% | ||
| \({ }^{123} \mathrm{I}\) | 13.0 h | EC | \(\gamma\) | 0.159 | \(\approx 100 \%\) | ||
| \({ }^{131} \mathrm{I}\) | 8.040 d | \(\beta^{-} \mathrm{s}\) | 0.248 | 7% | \(\gamma \mathrm{s}\) | 0.364 | 85% |
| 0.607 | 93% | others | |||||
| others | |||||||
| \({ }^{129} \mathrm{Cs}\) | 32.3 h | EC | \(\gamma \mathrm{s}\) | 0.0400 | 35% | ||
| 0.372 | 32% | ||||||
| 0.411 | 25% | ||||||
| others | |||||||
| \({ }^{137} \mathrm{Cs}\) | 30.17 y | \(\beta^{-} \mathrm{s}\) | 0.511 | 95% | \(\gamma\) | 0.662 | 95% |
| 1.17 | 5% | ||||||
| \({ }^{140} \mathrm{Ba}\) | 12.79 d | \(\beta^{-}\) | 1.035 | \(\approx 100 \%\) | \(\gamma \mathrm{s}\) | 0.030 | 25% |
| 0.044 | 65% | ||||||
| 0.537 | 24% | ||||||
| others | |||||||
| \({ }^{198} \mathrm{Au}\) | 2.696 d | \(\beta^{-}\) | 1.161 | \(\approx 100 \%\) | \(\gamma\) | 0.412 | \(\approx 100 \%\) |
| \({ }^{197} \mathrm{Hg}\) | 64.1 h | EC | \(\gamma\) | 0.0733 | 100% | ||
| \({ }^{210} \mathrm{Po}\) | 138.38 d | \(\alpha\) | 5.41 | 100% | |||
| \({ }^{226} \mathrm{Ra}\) | \(1.60 \times 10^{3} \mathrm{y}\) | \(\alpha \mathrm{s}\) | 4.68 | 5% | \(\gamma\) | 0.186 | 100% |
| 4.87 | 95% | ||||||
| \({ }^{235} \mathrm{U}\) | \(7.038 \times 10^{8} \mathrm{y}\) | \(\alpha\) | 4.68 | \(\approx 100 \%\) | \(\gamma \mathrm{s}\) | numerous | <0.400% |
| \({ }^{238} \mathrm{U}\) | \(4.468 \times 10^{9} \mathrm{y}\) | \(\alpha \mathrm{s}\) | 4.22 | 23% | \(\gamma\) | 0.050 | 23% |
| 4.27 | 77% | ||||||
| \({ }^{237} \mathrm{Np}\) | \(2.14 \times 10^{6} \mathrm{y}\) | \(\alpha \mathrm{s}\) | numerous | \(\gamma \mathrm{s}\) | numerous | <0.250% | |
| 4.96 (max.) | |||||||
| \({ }^{239} \mathrm{Pu}\) | \(2.41 \times 10^{4} \mathrm{y}\) | \(\alpha \mathrm{s}\) | 5.19 | 11% | \(\gamma \mathrm{s}\) | \(7.5 \times 10^{-5}\) | 73% |
| 5.23 | 15% | 0.013 | 15% | ||||
| 5.24 | 73% | 0.052 | 10% | ||||
| others | |||||||
| \({ }^{243} \mathrm{Am}\) | \(7.37 \times 10^{3} \mathrm{y}\) | \(\alpha \mathrm{s}\) | Max. 5.44 | \(\gamma \mathrm{s}\) | 0.075 | ||
| 5.37 | 88% | others | |||||
| 5.32 | 11% | ||||||
| others |