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HK: Fachverband Physik der Hadronen und Kerne
HK 55: Structure and Dynamics of Nuclei 11
HK 55.4: Talk
Thursday, March 26, 2015, 15:30–15:45, T/SR19
Investigation of reduced transition-strengths in neutron-rich chromium isotopes — •Thomas Braunroth1, Alfred Dewald1, Christoph Fransen1, Hironori Iwasaki2, Antoine Lemasson3, Silvia Lenzi4, and Julia Litzinger1 — 1Institut für Kernphysik, Universität zu Köln, Germany — 2National Superconducting Cyclotron Laboratory, MSU, USA — 3GANIL, Laboratoire Commun DSM/CEA, France — 4Department of Physics and Astronomy, University of Padova and INFN Sezione di Padova, Italy
Neutron-rich nuclei close to N=40 are known for their rapid changes in nuclear structure.
While 68Ni exhibits signatures of a shell closure, experimental data - e.g. excitation energies of the 21+-state and B(E2;21+ → 01+)-values - along the isotopic chains in even more exotic Fe and Cr-isotopes suggest a sudden rise in collective behaviour for N→ 40.
Lifetimes of low-lying yrast states in 58,60,62Cr were measured with the Recoil Distance Doppler-shift (RDDS) technique at NSCL, MSU (USA) to deduce model independent B(E2)-values.
After fragmentation of a primary 82Se beam (E=140 AMeV) on a 9Be target and subsequent filtering with the A1900 fragment separator, high purity 59,61,63Mn-beams (E∼ 95 AMeV) impinged on the 9Be plunger target, where excited states in the above mentioned Cr-isotopes were then populated in one proton knockout reactions. The S800 spectrograph allowed a clear recoil identification, which then lead to clean γ-spectra as measured by the Segmented Germanium Array (SeGA).
Final results of this experiment will be shown and discussed in the context of state-of-the-art shell-model calculations.