Discovery of W-157 and Os-161

L. Bianco, R. D. Page, I. G. Darby, D. T. Joss, J. Simpson, J. J. Al-Khalili, A. J. Cannon, B. Cederwall, S. Eeckhaudt, S. Erturk, B. Gall, M. B. Gomez Hornillos, T. Grahn, P. T. Greenlees, B. Hadinia, K. Heyde, U. Jakobsson, P. M. Jones, R. Julin, S. JuutinenS. Ketelhut, M. Labiche, M. Leino, A. -P. Leppanen, M. Nyman, D. O'Donnell, E. S. Paul, M. Petri, P. Peura, A. Puurunen, P. Rahkila, P. Ruotsalainen, M. Sandzelius, P. J. Sapple, J. Saren, C. Scholey, N. A. Smirnova, A. N. Steer, P. D. Stevenson, E. B. Suckling, J. Thomson, J. Uusitalo, M. Venhart

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16 Citations (Scopus)


The nuclides 157W and 161Os have been discovered in reactions of 58Ni ion beams with a 106Cd target. The 161Os α -decay energy and half-life were 6890±12 keV6890±12 keV and 640±60 μs640±60 μs. The daughter 157W nuclei β -decayed with a half-life of 275±40 ms275±40 ms, populating both low-lying α-decaying states in 157Ta, which is consistent with a 7/2−7/2− ground state in 157W. Fine structure observed in the α decay of 161Os places the lowest excited state in 157W with Iπ=9/2−Iπ=9/2− at 318±30 keV318±30 keV. The branching ratio of View the MathML source5.5−2.2+3.1% indicates that 161Os also has a 7/2−7/2− ground state. Shell-model calculations analysing the effects of monopole shifts and a tensor force on the relative energies of 2f7/22f7/2 and 1h9/21h9/2 neutron states in N=83N=83 isotones are presented.
Original languageEnglish
Pages (from-to)15-18
Number of pages4
JournalPhysics Letters B
Issue number1
Publication statusPublished - 2010
Externally publishedYes


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