Law-spin states from decay studies in the mass 80 region

Neutron-deficient nuclei in the mass 80 region are known to exhibit strongl y deformed ground states deduced mainly from yrast-state properties measure d in-beam via heavy-ion fusion-evaporation reactions. Vibrational excitatio ns and non-yrast states as well as their interplay with the observed rotati onal collectivity have been less studied to date within this mass region. T hus, several beta-decay experiments have been performed to populate low-spi n states in the neutron-deficient Y-80.84 and Sr-80.84 nuclei. An overview of excited 0(+) states in Sr and Kr nuclei is given and conclusions about s hape evolution at low-spins are presented. In general, the non-yrast states in even-even Sr nuclei show mainly vibration-like collectivity which evolv es to rotational behavior with increasing spin and decreasing neutron numbe r.