Lifetime measurements with improved precision in S-30,S-32 and possible influence of large-scale clustering on the appearance of strongly deformed states

摘要

The formation of large size clusters and/or their relative motion as possible excitation mode are suggested to be closely related to the origin of deformation in specific cases. In S-32, the consideration of some excitations in this nucleus as based on the existence of two doubly magic O-16 clusters offers a possible solution to the long-standing problem of missing quadrupole collectivity in shell-model calculations aiming to describe electromagnetic E-2 transition strengths and quadrupole moments. To experimentally check again this collectivity, lifetime measurements were performed on S-30 and S-32. In S-32, at least, the reproduction of a number of observables supports the cluster scenario. Additionally, the superdeformed yrast band in Zr-80 could find an explanation as based on the relative motion of two Ca-40 clusters. Simultaneously, a necessity arises to revise experimentally some lifetimes derived in the past within the Blaugrund approximation when using the Doppler-shift attenuation method.