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College Physics for AP® Courses 2e

B | Selected Radioactive Isotopes

College Physics for AP® Courses 2eB | Selected Radioactive Isotopes

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

Isotope t 1/2 DecayMode(s) Energy(MeV) Percent γγ-Ray Energy(MeV) Percent
3 H 3 H 12.33 y β−β− ­ 0.0186 100%
14 C 14 C 5730 y β − β − 0.156 100%
13 N 13 N 9.96 min β + β + 1.20 100%
22 Na 22 Na 2.602 y β + β + 0.55 90% γ γ 1.27 100%
32 P 32 P 14.28 d β − β − 1.71 100%
35 S 35 S 87.4 d β−β− ­ 0.167 100%
36 Cl 36 Cl 3 . 00 × 10 5 y 3 . 00 × 10 5 y β − β − 0.710 100%
40 K 40 K 1 . 28 × 10 9 y 1 . 28 × 10 9 y β − β − 1.31 89%
43 K 43 K 22.3 h β − β − 0.827 87% γ s γ s 0.373 87%
0.618 87%
45 Ca 45 Ca 165 d β−β− ­ 0.257 100%
51 Cr 51 Cr 27.70 d EC γ γ 0.320 10%
52 Mn 52 Mn 5.59d β + β + 3.69 28% γ s γ s 1.33 28%
1.43 28%
52 Fe 52 Fe 8.27 h β + β + 1.80 43% 0.169 43%
0.378 43%
59 Fe 59 Fe 44.6 d β − s β − s 0.273 45% γ s γ s 1.10 57%
0.466 55% 1.29 43%
60 Co 60 Co 5.271 y β−β− ­ 0.318 100% γ s γ s 1.17 100%
1.33 100%
65 Zn 65 Zn 244.1 d EC γ γ 1.12 51%
67 Ga 67 Ga 78.3 h EC γ s γ s 0.0933 70%
0.185 35%
0.300 19%
others
75 Se 75 Se 118.5 d EC γ s γ s 0.121 20%
0.136 65%
0.265 68%
0.280 20%
others
86 Rb 86 Rb 18.8 d β − s β − s 0.69 9% γ γ 1.08 9%
1.77 91%
85 Sr 85 Sr 64.8 d EC γ γ 0.514 100%
90 Sr 90 Sr 28.8 y β−β− ­ 0.546 100%
90 Y 90 Y 64.1 h β−β− ­ 2.28 100%
99m Tc 99m Tc 6.02 h IT γ γ 0.142 100%
113m In 113m In 99.5 min IT γ γ 0.392 100%
123 I 123 I 13.0 h EC γ γ 0.159 ≈100% ≈100%
131 I 131 I 8.040 d β − s β − s 0.248 7% γ s γ s 0.364 85%
0.607 93% others
others
129 Cs 129 Cs 32.3 h EC γ s γ s 0.0400 35%
0.372 32%
0.411 25%
others
137 Cs 137 Cs 30.17 y β−sβ−s ­ 0.511 95% γ γ 0.662 95%
1.17 5%
140 Ba 140 Ba 12.79 d β − β − 1.035 ≈100% ≈100% γ s γ s 0.030 25%
0.044 65%
0.537 24%
others
198 Au 198 Au 2.696 d β−β− ­ 1.161 ≈100% ≈100% γ γ 0.412 ≈100% ≈100%
197 Hg 197 Hg 64.1 h EC γ γ 0.0733 100%
210 Po 210 Po 138.38 d α α 5.41 100%
226 Ra 226 Ra 1 . 60 × 10 3 y 1 . 60 × 10 3 y α s α s 4.68 5% γ γ 0.186 100%
4.87 95%
235 U 235 U 7 . 038 × 10 8 y 7 . 038 × 10 8 y α α 4.68 ≈100% ≈100% γ s γ s numerous <0.400%
238 U 238 U 4 . 468 × 10 9 y 4 . 468 × 10 9 y α s α s 4.22 23% γ γ 0.050 23%
4.27 77%
237 Np 237 Np 2 . 14 × 10 6 y 2 . 14 × 10 6 y α s α s numerous γ s γ s numerous <0.250%
4.96 (max.)
239 Pu 239 Pu 2 . 41 × 10 4 y 2 . 41 × 10 4 y α s α s 5.19 11% γ s γ s 7 . 5 × 10 − 5 7 . 5 × 10 − 5 73%
5.23 15% 0.013 15%
5.24 73% 0.052 10%
others
243 Am 243 Am 7 . 37 × 10 3 y 7 . 37 × 10 3 y α s α s Max. 5.44 γ s γ s 0.075
5.37 88% others
5.32 11%
others
Table B1 Selected Radioactive Isotopes
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