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HK: Fachverband Physik der Hadronen und Kerne

HK 20: Struktur und Dynamik von Kernen

HK 20.8: Talk

Monday, March 4, 2013, 18:45–19:00, HSZ-401

Detailed investigation of octupole vibrational states in ¹⁶⁸Yb — •Sorin Pascu, Vera Derya, Janis Endres, Andreas Hennig, Lars Netterdon, Simon G. Pickstone, Mark Spieker, and Andreas Zilges — Institut für Kernphysik, Universität zu Köln

The experimental evidence for the presence of octupole vibrational states in ¹⁶⁸Yb is presented. In order to populate the excited states in this nucleus, the ¹⁶⁶Er(α,2nγ)¹⁶⁸Yb fusion evaporation reaction was used with a beam energy of 24 MeV. Using the coincidence method, the level scheme was corrected and extended up to 3 MeV, both for the positive and negative parity states. In a second step, the lifetimes of five excited states were measured by using the fast timing method with the Bucharest HPGe and LaBr₃:Ce detector array using the triple-γ coincidence method. Reduced E1 and E2 transition probabilities were extracted from the measured lifetimes and compared, when possible, with similar observables in neighboring isotopes, showing a smooth behavior with increasing mass. The positive and negative-parity states revealed by this experiment are compared with the Interacting Boson Model and are found to be in good agreement.

Supported by the DFG (ZI 510/4-2). V. D., A. H., S. G. P., and M. S. are members of the Bonn-Cologne Graduate School of Physics and Astronomy