Resolution of a possible misinterpretation of the nuclear excitation mode along the yrast line: An investigation on the evolution of rotation and vibration

Abstract

An empirical approach, called E-GOS ($E$-gamma over spin) curves, which is used for discerning the evolution between vibration and rotation in nuclei as a function of spin, is discussed. Considering the possible mechanisms and the results of total-Routhian-surface calculations, we find that the decrease in an E-GOS plot may be misinterpreted as the onset of vibration behavior along the yrast line. The insufficiency of the vibration-like criterion of the E-GOS curves to determine the transition from rotation to vibration is emphasized. It is pointed out that the crossing between the ground-state and $S$ bands, especially with a strong interaction, will be responsible for such vibration-like evolution of nuclear excitation modes.