It's Elemental - Isotopes of the Element Neptunium

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Most of the isotope data on this site has been obtained from the National Nuclear Data Center. Please visit their site for more information.

All Known Isotopes of the Element Neptunium

Mass Number		Half-life		Decay Mode		Branching Percentage

225		> 2 microseconds		Alpha Decay		100.00

226		35 milliseconds		Alpha Decay		100.00

227		0.51 seconds		Alpha Decay		100.00

228		61.4 seconds		Electron Capture		60.00

				Alpha Decay		40.00

229		4.0 minutes		Alpha Decay		> 50.00

				Electron Capture		< 50.00

230		4.6 minutes		Electron Capture		<= 97.00

				Alpha Decay		>= 3.00

231		48.8 minutes		Electron Capture		98.00

				Alpha Decay		2.00

232		14.7 minutes		Electron Capture		100.00

233		36.2 minutes		Electron Capture		100.00

				Alpha Decay		<= 1.0E-3

234		4.4 days		Electron Capture		100.00

235		396.1 days		Electron Capture		100.00

				Alpha Decay		2.6E-3

236		154×10⁺³ years		Electron Capture		87.30

				Beta-minus Decay		12.50

				Alpha Decay		0.16

236_m		22.5 hours		Electron Capture		52.00

				Beta-minus Decay		48.00

237		2.144×10⁺⁶ years		Alpha Decay		100.00

				Spontaneous Fission		<= 2E-10

238		2.117 days		Beta-minus Decay		100.00

239		2.3565 days		Beta-minus Decay		100.00

240		61.9 minutes		Beta-minus Decay		100.00

240_m		7.22 minutes		Beta-minus Decay		99.89

241		13.9 minutes		Beta-minus Decay		100.00

242		2.2 minutes		Beta-minus Decay		100.00

242_m		5.5 minutes		Beta-minus Decay		100.00

243		1.85 minutes		Beta-minus Decay		100.00

244		2.29 minutes		Beta-minus Decay		100.00

This page is maintained by Steve Gagnon.

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