New Isotopes of Neptunium

L. B. Magnusson; S. G. Thompson; G. T. Seaborg

doi:10.1103/PhysRev.78.363

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New Isotopes of Neptunium

L. B. Magnusson^*, S. G. Thompson, and G. T. Seaborg

Radiation Laboratory and Department of Chemistry, University of California, Berkeley, California

^*Now at Argonne National Laboratory, Chicago, Illinois.

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Phys. Rev. 78, 363 – Published 15 May, 1950

DOI: https://doi.org/10.1103/PhysRev.78.363

Abstract

Evidence is presented for three new, light neptunium isotopes formed by deuteron bombardments of $U^{233}$ , $U^{235}$ , and $U^{238}$ . The isotope ${Np}^{231}$ has a half-life of 50±3 min. and emits alpha-particles of 6.28-Mev energy; the proportion of decay by electron-capture has not been determined. The isotope ${Np}^{233}$ decays predominantly by electron-capture with a 35±3-min, half-life; it has an alpha-decay half-life roughly determined to be $ca$ . 10 yr. corresponding to a $\frac{K}{α}$ -branching ratio of 1.5× $10^{5}$ and the alpha-particles have an energy of 5.53 Mev. A 13±3-min. period with electromagnetic radiation, indicating orbital electroncapture, is attributed to ${Np}^{232}$ . Approximate cross sections for formation of various neptunium isotopes by deuterons of energy from 15 to 100 Mev have been determined. The cross sections are low, of the order of $10^{- 26}$ ${cm}^{2}$ , possibly because most of the excited nuclei undergo fission.

References (19)

E. M. McMillan, Phys. Rev. 55, 510 (1939)
E. M. McMillan and P. H. Abelson, Phys. Rev. 57, 1185 (1940)
Seaborg, McMillan, Wahl, and Kennedy, Phys. Rev. 69, 366 (1946) The Transuranium Elements: Research Papers (McGraw-Hill Book Company, Inc., New York, 1949), Paper No. 1.1, National Nuclear Energy Series, Plutonium Project Record Vol. 14B
Seaborg, Wahl, and Kennedy, Phys. Rev. 69, 367 (1946) National Nuclear Energy Series, Plutonium Project Record Vol. 14B
Kennedy, Perlman, Segrè, and Wahl, National Nuclear Energy Series, Plutonium Project Record Vol. 14B
A. C. Wahl and G. T. Seaborg, Phys. Rev. 73, 940 (1948) National Nuclear Energy Series, Plutonium Project Record Vol. 14B
L. B. Magnusson and T. J. LaChapelle, J. Am. Chem. Soc. 70, 3534 (1948) National Nuclear Energy Series, Plutonium Project Record Vol. 14B
Hindman, Magnusson, and LaChapelle, J. Am. Chem. Soc. 71, 687 (1949) National Nuclear Energy Series, Plutonium Project Record Vol. 14B
S. Fried and N. Davidson, J. Am. Chem. Soc. 70, 3539 (1948) National Nuclear Energy Series, Plutonium Project Record Vol. 14B
J. J. Katz and D. M. Gruen, J. Am. Chem. Soc. 71, 2106 (1949)
James, Florin, Hopkins, and Ghiorso, National Nuclear Energy Series, Plutonium Project Record Vol. 14B AEC declassified document No. 2495 (1949)
Hyde, Studier, and Ghiorso, National Nuclear Energy Series, Plutonium Project Record Vol. 14B AEC declassified document No. 2572 (1949)
G. T. Seaborg and I. Perlman, Rev. Mod. Phys. 20, 585 (1948)
R. A. James (unpublished data)
Perlman, Ghiorso, and Seaborg, Phys. Rev. 74, 1730 (1948) ibid.75, 1096 (1949) ibid.77, 26 (1950)
Ghiorso, Jaffey, Robinson, and Weissbourd, National Nuclear Energy Series, Plutonium Project Record Vol. 14B
Meinke, Ghiorso, and Seaborg, Phys. Rev. 74, 695 (1948)
James, Orth, and Street (unpublished work)
R. Serber, Phys. Rev. 72, 1114 (1947)

[c1] E. M. McMillan, Phys. Rev. 55, 510 (1939)

[c2] E. M. McMillan and P. H. Abelson, Phys. Rev. 57, 1185 (1940)

[c3] Seaborg, McMillan, Wahl, and Kennedy, Phys. Rev. 69, 366 (1946) The Transuranium Elements: Research Papers (McGraw-Hill Book Company, Inc., New York, 1949), Paper No. 1.1, National Nuclear Energy Series, Plutonium Project Record Vol. 14B

[c4] Seaborg, Wahl, and Kennedy, Phys. Rev. 69, 367 (1946) National Nuclear Energy Series, Plutonium Project Record Vol. 14B

[c5] Kennedy, Perlman, Segrè, and Wahl, National Nuclear Energy Series, Plutonium Project Record Vol. 14B

[c6] A. C. Wahl and G. T. Seaborg, Phys. Rev. 73, 940 (1948) National Nuclear Energy Series, Plutonium Project Record Vol. 14B

[c7] L. B. Magnusson and T. J. LaChapelle, J. Am. Chem. Soc. 70, 3534 (1948) National Nuclear Energy Series, Plutonium Project Record Vol. 14B

[c8] Hindman, Magnusson, and LaChapelle, J. Am. Chem. Soc. 71, 687 (1949) National Nuclear Energy Series, Plutonium Project Record Vol. 14B

[c9] S. Fried and N. Davidson, J. Am. Chem. Soc. 70, 3539 (1948) National Nuclear Energy Series, Plutonium Project Record Vol. 14B

[c10] J. J. Katz and D. M. Gruen, J. Am. Chem. Soc. 71, 2106 (1949)

[c11] James, Florin, Hopkins, and Ghiorso, National Nuclear Energy Series, Plutonium Project Record Vol. 14B AEC declassified document No. 2495 (1949)

[c12] Hyde, Studier, and Ghiorso, National Nuclear Energy Series, Plutonium Project Record Vol. 14B AEC declassified document No. 2572 (1949)

[c13] G. T. Seaborg and I. Perlman, Rev. Mod. Phys. 20, 585 (1948)

[c14] R. A. James (unpublished data)

[c15] Perlman, Ghiorso, and Seaborg, Phys. Rev. 74, 1730 (1948) ibid.75, 1096 (1949) ibid.77, 26 (1950)

[c16] Ghiorso, Jaffey, Robinson, and Weissbourd, National Nuclear Energy Series, Plutonium Project Record Vol. 14B

[c17] Meinke, Ghiorso, and Seaborg, Phys. Rev. 74, 695 (1948)

[c18] James, Orth, and Street (unpublished work)

[c19] R. Serber, Phys. Rev. 72, 1114 (1947)

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New Isotopes of Neptunium

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