Köln 2004 – wissenschaftliches Programm

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HK: Physik der Hadronen und Kerne

HK 19: Nuclear Structure/Spectroscopy III

HK 19.10: Vortrag

Dienstag, 9. März 2004, 18:15–18:30, D

Low-Spin γ-Ray Spectroscopy of the Doubly-Magic Nucleus ⁵⁶Ni with the MINIBALL-Spectrometer — •D. Mücher¹, C. Fransen¹, N. Pietralla^1,2, J. Eberth¹, N. Warr¹, and D. Weisshaar¹ — ¹Institut für Kernphysik, Universität zu Köln — ²Dept. of Physics, SUNY, Stony Brook, USA

The doubly closed-shell N=Z nucleus ₂₈⁵⁶Ni is of particular interest for understanding nuclear structure in the fp-shell. In recent years large-scale shell model calculations for this region became possible. The microscopic description of the excitation of ⁵⁶Ni remained one of the biggest challenges for theory. While deformed high-spin structures of ⁵⁶Ni are well investigated [1], information on low-spin states was sparse. We investigated ⁵⁶Ni with the reaction ⁵⁴Fe(³He,nγ)⁵⁶Ni at the Cologne FN-Tandem accelerator with the highly efficient Miniball-spectrometer. γγ-coincidence data were measured for excited states up to an excitation energy of about 9 MeV. The known γ-decay scheme for low-spin states has been more than doubled and several branching ratios were determined. The set-up and data will be presented. The spectrometer performance will be discussed. The data will be compared to the newest large-scale Monte-Carlo shell model calculations by the Tokyo group using the GXPF1 interaction [2].

Supported by the Emmy Noether-Program of the DFG under Pi393/1-2 and by BMBF under 06OK958

[1] D. Rudolph et al.,Phys.Rev.Lett. 82, 3763 (1999)

[2] M. Honma, T. Otsuka et al., priv. comm., submitted for publication