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Chapter 16: Selected Radioactive Isotopes

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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 Chapter16.1: Selected Radioactive Isotopes
Isotope t 1/2 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 3.00×105y β 0.710 100%    
40K 1.28×109y 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 0.392 100%
123I 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

This page titled Chapter 16: Selected Radioactive Isotopes is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by OpenStax.

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