Rotational to vibrational evolution in some rotational-like nuclei

摘要

The excitation spectra of nuclei in the regions 150 < A < 190 and 220 < A < 250 are commonly considered as showing the characteristics of the rotational motion.Whereas in the present work,there is important evidence to indicate that the nuclei discussed transit from rotation to vibration.At present,we encounter two different simple nuclear models being used for the elucidation of different region (lower and higher spin states) of the same nucleus.In addition,in order to study these rotational-like nuclei,as an example,shape calculations using the total Routhian surfaces (TRS) model were carried out for positive-parity states in 156Gd.Also we have shown the result of the nucleus 102Ru which is given as an example of the reverse transition,i.e.,vibration to rotation.The TRS plots reveal that,as the spin increases up the band,the former nucleus becomes slightly soft in γ and β direction,whereas the latter becomes rigid in γ direction.