STRUCTURE OF THE N=59 NUCLEUS SR-97 - COEXISTENCE OF SPHERICAL AND DEFORMED STATES

A band with a rotational pattern based on a state at 585.1 keV has been identified in the N=59 neutron-rich nucleus97Sr. Its properties lead to the [422] 3/2 Nilsson-orbital assignment for the band head. There is evidence for a second band with the head at 644.7 keV and the configuration [541] 3/2. Since the ground state and the lowest excited levels are spherical, shape coexistence is established for97Sr. A deformed nature of several levels at 500-600 keV results also from QRPA-model calculations. The structure of the low-lying spherical levels has been studied in the frame of the IBF model. The results of the present investigations lead to a better understanding of the N=59 isotones which constitute the link between the spherical and deformed nuclei at A∼100 as a species with shape coexistence but without any indications of particular softness. © 1990 Springer-Verlag.