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HK: Physik der Hadronen und Kerne
HK 16: Postersitzung / Kernphysik
HK 16.23: Poster
Donnerstag, 23. März 2000, 10:15–12:45, B 69
Isomer study of 90216Th126 and the predicted Z=92 subshell closure — •H. Grawe1, M. Rejmund1,2,3, K. Hauschild4, M. Górska1,2, J. Döring1, K. Schmidt1, F. Azaiez3, M. Belleguic3, W. Korten4, K. Helariutta5, P. Jones5, R. Julin5, M. Leino5, and J. Uusitalo5 — 1GSI Darmstadt, Planckstr. 1, D–64291 Darmstadt, Germany — 2IEP, University of Warsaw — 3IPNO, Orsay — 4CNSM, Saclay — 5JYFL, Jyväskylä
Recent mean field predictions for the shell structure of super-heavy elements imply a subshell closure for Z=92 and N=126 for some of the employed interactions [1]. This is at variance with systematic trends observed in the spectroscopy of N=126 isotones up to Z=89 [2]. In an experiment performed at the Jyväskylä cyclotron we have exploited the α-recoil decay-tagging method to study the isomeric γ- decay in 90216Th126 in the focal plane of the gas-filled separator RITU [3].
Three isomers with tentative spin-parity assignments Iπ=(8+), (11−) and (14+) were identified. The decay pattern and the γ-ray transition strengths determine the configurations as proton [h9/2−3 f7/2]8+,14+ and [h9/2−3 i13/2]11−, respectively, and establish a low-lying Iπ=(3−) state. No subshell gap is found to exist between the π h9/2 and π f7/2 orbits, which causes distortion of the h9/2n seniority scheme.
[1] M. Bender et al., Phys. Rev. C60, 034304 (1999)
[2] D. Decman et al., Z. Phys. A310, 55 (1983)
[3] K. Helariutta et al., Phys. Rev. C54, R2799 (1996)