Centrifugal stretching of 170Hf in the interacting boson model

We present the results of a recent experiment to deduce lifetimes of members of the ground state rotational band of 170Hf, which show the effect of centrifugal stretching in this deformed isotope. Results are compared to the geometrical confined beta-soft(CBS) rotor model, as well as to the interacting boson model (IBM). Two methods to correct for effects due to the finite valence space within the IBM are proposed.