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HK: Fachverband Physik der Hadronen und Kerne

HK 5: Structure and Dynamics of Nuclei I

HK 5.6: Talk

Monday, March 14, 2016, 15:30–15:45, S1/01 A03

Spectroscopy in neutron-rich nuclei in the vicinitiy of N=40 — •Thomas Braunroth¹, Alfred Dewald¹, Christoph Fransen¹, Hironori Iwasaki², Jan Jolie¹, and Julia Litzinger¹ — ¹Institut für Kernphysik, Universität zu Köln, Germany — ²National Superconducting Cyclotron Laboratory, MSU, USA

The development of collectivity towards N=40 in neutron-rich nuclei between ₂₀Ca and ₂₈Ni shows a distinct Z-dependence. While ⁶⁸Ni exhibits features of a pronounced shell-gap, the evolution of key observables, e.g. excitation energies and B(E2) values, in even-even ₂₆Fe and ₂₄Cr isotopes is interpreted as a rapidly evolving quadrupole deformation when N=40 is approached. However, experimental information on level energies and reduced transitions strengths are still sparse in this particular region of the nuclear landscape. To shed more light on the evolution of collectivity along even-even Cr isotopes towards N=40, we performed an experiment at NSCL, MSU (USA) in which lifetimes of excited states were measured with the recoil distance Doppler-shift technique. The experiment focused on the 2₁⁺ and 4₁⁺ states in ^58,60,62Cr and corresponding results have been published recently [1]. In addition, various excited states in neighbouring nuclei with 23 ≲ Z ≲ 26 close to N=40 were populated and some spectroscopic information on transition energies and level lifetimes can be deduced. Some of them are determined for the first time. In this talk we will present preliminary results of such side reactions. This work is supported by the BMBF under contract number 05P12PKFNE.

[1] T. Braunroth et al., Phys. Rev. C 92, 034306 (2015)