Lifetimes of unresolved transitions from very high spin states in nuclei nearN=82

Abstract

Average lifetimes of unresolved transitions deexciting very high spin states populated in28Si(136, 129Xe,xn)164−x, 157−xEr reactions have been determined by a Doppler shift attenuation method. We find that the yrast bump region between 1.0 and 1.6 MeV contains a majority of strongly collectiveE2 transitions with very short lifetimes (a few tens of fsec) in the well deformed nuclei around159Er and, with less certainty, almost comparably short lifetimes in the more spherical nuclei around152Er. In the high energy region of 2.0–3.2 MeV we observe transitions which depopulate longer lived states in the nuclei nearN=82 than in the well deformed systems.