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HK: Fachverband Hadronen und Kerne

HK 67: Poster Session

HK 67.50: Poster

Thursday, March 19, 2009, 14:00–16:00, Audi-Max

Evidence for an isomeric 3/2⁻ state in ⁵³Co — Dirk Rudolph¹ and •Robert Hoischen^1,2 — ¹Department of Physics, Lund University, S-22100 Lund, Sweden — ²Helmholtzzentrum für Schwerionenforschung GmbH, D-64291 Darmstadt, Germany

The fragmentation of a 550 MeV/u primary beam of ⁵⁸Ni on a ⁹Be target has been used to measure time- and energy-correlated γ decays following the implantation of event-by-event discriminated secondary fragments into a ⁹Be stopper plate. A new isomeric γ decay with T_1/2=14(₄⁶) ns and E_γ=646.2(2) keV is observed and attributed to the decay of the yrast 3/2⁻ state in ₂₇⁵³Co₂₆. This short-lived isomeric state has been populated by means of nuclear reactions during the stopping process of the secondary fragments. The experimental findings are discussed in the framework of large-scale spherical shell-model calculations in conjunction with isospin symmetry breaking residual interactions for the A=53, T_z=± 1/2 mirror nuclei ⁵³Co and ⁵³Fe.