Systematic study of E2 transitions from I=4 level of gamma vibrational band in even-even deformed nuclei

The Asymmetric Rotor Model (ARM) of Davydov-Rostovsky (DR) has been employed to evaluate the B(E2) branching ratios depopulating I=4 gamma vibrational band in even-even nuclei covering rare earth and actinide regions. The present results are compared with known experimental values and other available phenomenological and microscopic model values. The calculated DR values show a better agreement with experimental values as compared to the microscopic model values. It establishes Kπ=2+, I=4 level as a member of classical gamma vibrational band originating from collective excitations and, therefore, goes against the view point of Zawischa et.al. who doubted the vibrational nature of even deformed nuclei. The better results of the Davydov-Rostovsky (dynamic) model over the Davydov-Filippov (rigid) model indicate that the nucleus now gets rid of its rigid shape and attains freedom in β and γ directions. (author)