Selected Radioactive Isotopes, Front matter | College Physics 2e

Learning objectives

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 $β^{\pm}$ decays are the maxima; average energies are roughly one-half the maxima.

Selected Radioactive Isotopes
Isotope	t _1/2	DecayMode(s)	Energy(MeV)	Percent		$γ$ -Ray Energy(MeV)	Percent
$^{3} H$	12.33 y	$β^{-}$	0.0186	100%
$^{14} C$	5730 y	$β^{-}$	0.156	100%
$^{13} N$	9.96 min	$β^{+}$	1.20	100%
$^{22} Na$	2.602 y	$β^{+}$	0.55	90%	$γ$	1.27	100%
$^{32} P$	14.28 d	$β^{-}$	1.71	100%
$^{35} S$	87.4 d	$β^{-}$	0.167	100%
$^{36} Cl$	$3 . 00 \times 10^{5} y$	$β^{-}$	0.710	100%
$^{40} K$	$1 . 28 \times 10^{9} y$	$β^{-}$	1.31	89%
$^{43} K$	22.3 h	$β^{-}$	0.827	87%	$γ s$	0.373	87%
						0.618	87%
$^{45} Ca$	165 d	$β^{-}$	0.257	100%
$^{51} Cr$	27.70 d	EC			$γ$	0.320	10%
$^{52} Mn$	5.59d	$β^{+}$	3.69	28%	$γ s$	1.33	28%
						1.43	28%
$^{52} Fe$	8.27 h	$β^{+}$	1.80	43%		0.169	43%
						0.378	43%
$^{59} Fe$	44.6 d	$β^{-} s$	0.273	45%	$γ s$	1.10	57%
			0.466	55%		1.29	43%
$^{60} Co$	5.271 y	$β^{-}$	0.318	100%	$γ s$	1.17	100%
						1.33	100%
$^{65} Zn$	244.1 d	EC			$γ$	1.12	51%
$^{67} Ga$	78.3 h	EC			$γ s$	0.0933	70%
						0.185	35%
						0.300	19%
						others
$^{75} Se$	118.5 d	EC			$γ s$	0.121	20%
						0.136	65%
						0.265	68%
						0.280	20%
						others
$^{86} Rb$	18.8 d	$β^{-} s$	0.69	9%	$γ$	1.08	9%
			1.77	91%
$^{85} Sr$	64.8 d	EC			$γ$	0.514	100%
$^{90} Sr$	28.8 y	$β^{-}$	0.546	100%
$^{90} Y$	64.1 h	$β^{-}$	2.28	100%
$^{99m} Tc$	6.02 h	IT			$γ$	0.142	100%
$^{113m} In$	99.5 min	IT			$γ$	0.392	100%
$^{123} I$	13.0 h	EC			$γ$	0.159	$≈100%$
$^{131} I$	8.040 d	$β^{-} s$	0.248	7%	$γ s$	0.364	85%
			0.607	93%		others
			others
$^{129} Cs$	32.3 h	EC			$γ s$	0.0400	35%
						0.372	32%
						0.411	25%
						others
$^{137} Cs$	30.17 y	$β^{-} s$	0.511	95%	$γ$	0.662	95%
			1.17	5%
$^{140} Ba$	12.79 d	$β^{-}$	1.035	$≈100%$	$γ s$	0.030	25%
						0.044	65%
						0.537	24%
						others
$^{198} Au$	2.696 d	$β^{-}$	1.161	$≈100%$	$γ$	0.412	$≈100%$
$^{197} Hg$	64.1 h	EC			$γ$	0.0733	100%
$^{210} Po$	138.38 d	$α$	5.41	100%
$^{226} Ra$	$1 . 60 \times 10^{3} y$	$α s$	4.68	5%	$γ$	0.186	100%
			4.87	95%
$^{235} U$	$7 . 038 \times 10^{8} y$	$α$	4.68	$≈100%$	$γ s$	numerous	<0.400%
$^{238} U$	$4 . 468 \times 10^{9} y$	$α s$	4.22	23%	$γ$	0.050	23%
			4.27	77%
$^{237} Np$	$2 . 14 \times 10^{6} y$	$α s$	numerous		$γ s$	numerous	<0.250%
			4.96 (max.)
$^{239} Pu$	$2 . 41 \times 10^{4} y$	$α s$	5.19	11%	$γ s$	$7 . 5 \times 10^{- 5}$	73%
			5.23	15%		0.013	15%
			5.24	73%		0.052	10%
						others
$^{243} Am$	$7 . 37 \times 10^{3} y$	$α s$	Max. 5.44		$γ s$	0.075
			5.37	88%		others
			5.32	11%
			others

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