EuNPC2015

A study of the nuclear structure of 81Ge has been performed in order to better understand shell evolution in neutron-rich nuclei near the doubly magic 78Ni. The experiment was performed at the CERN ISOLDE facility in the framework of a systematic ultra-fast timing [1] investigation of neutron rich nuclei populated in the decay of Zn. The use of the ISOLDE RILIS and a cooled transfer line between the ion source and the target [2] made it possible to produce a pure beam of 81Zn ions, which was delivered to our compact fast-timing station equipped with two LaBr3(Ce) detectors, a plastic scintillator and two HPGe detectors. In this work, we present the 81Ge results arising from the analysis of the γ-γ HPGe coincidences and the fast-timing analysis based on β-γ(t) and β-γ-γ(t) events involving the fast scintillators. The level scheme presents 10 new levels and 15 new γ transitions with respect to the recent studies [3]. The decay half-life of 81Ga was determined by using the strongest γ-rays from the decay. Several half-lives of excited states up to 2 MeV in 81Ge have been measured. Based on these measurements and the improved level scheme, the spin-parity assignments will be discussed and compared with shell-model calculations. [1] H. Mach, R.L. Gill and M. Moszynski, Nucl. Instrum. Meth. A 280, 49 (1989). [2] U. Köster et al., Nucl. Instrum. Meth. B 266, 4229 (2008). [3] P. Hoff and B. Fogelberg, Nucl. Phys. A 36, 210 (1981).