Lifetime measurements of yrast states in Yb162 and Hf166

Abstract

Lifetime measurements of yrast levels in Yb162 and Hf166 were performed using the recoil distance Doppler-shift method in coincidence mode. Excited states in Yb162 and Hf166 were populated via the reactions Cd116(Ti50, 4n) and Sn122(Ti48, 4n), respectively. The resulting B(E2) values are compared with the X(5) critical point model predictions and interacting boson approximation (IBA) model calculations. The X(5) model provides a reasonable description of the yrast B(E2) values in Hf166, whereas the IBA fails to reproduce the transition strengths from the higher spin levels. In Yb162, some transitions agree with the X(5) predictions while others are more consistent with the predictions of the IBA or a deformed symmetric rotor. Show more