Possible Shape Transition in the Yrast Band ofFe56

Abstract
Spin and parity assignments and lifetime measurements on high-spin states of Fe56 have been made by γ-ray spectroscopy in various reactions. The results show that the first 6+ and 8+ states are not members of the ground-state rotational band with prolate deformation, indicating a sudden change in nuclear shape at J>4 along the yrast band of Fe56.