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HK: Fachverband Physik der Hadronen und Kerne

HK 65: Structure and Dynamics of Nuclei XII

HK 65.5: Vortrag

Donnerstag, 14. März 2024, 17:00–17:15, HBR 19: C 5a

Shell model investigations along the N=31 and Z=28 chains — •Ramona Burggraf, Peter Reiter, Konrad Arnswald, Andrey Blazhev, Maximilian Droste, Christoph Fransen, and Hannah Kleis — IKP, Universität zu Köln

Lifetime measurements of excited states along the N=31 chain were performed in order to investigate the N=32 sub-shell closure at higher masses near proton magic number Z=28. Precise lifetime values for excited states were determined in ⁵⁹Ni and ⁵⁷Fe, which were populated in ⁵¹V(¹²C, p3n) and ⁵¹V(¹²C, pnα) fusion-evaporation reactions at a beam energy of 55 MeV at the FN tandem accelerator of the University of Cologne. The Cologne plunger device, surrounded by an efficient γ-ray detector array was used to determine lifetimes with the recoil-distance Doppler-shift method. The newly determined values differ significantly from previous experimental results. New shell-model calculations employing the GXPF1A interaction were performed for nuclei along the N=31 and Z=28 chains. The evaluated previous experimental B(E2; 9/2⁻ → 5/2⁻) values for the N=31 isotone chain do not show reduced lower values at the Z=28 shell closure which is in contrast to the results of the shell model calculations. However, the newly determined lifetime values are consistent with the latest theoretical findings.

Keywords: Shell model; Lifetime measurements