Investigating the nature of the Er isotopes with ( p , t ) reactions

A series of (p,t) reactions have been performed at the Maier-Leibnitz Laboratory using beams of 22 or 24 MeV protons, and the reaction products were analysed with the Q3D spectrograph. The goals of the measurements were to investigate the population of low-lying states in 160,162,164,166Er. A number of low-lying 0+ states have been observed, and their population strengths relative to the ground states extracted. The results confirm the strong population of the 0+_2 state in 164Er observed previously, and that the 0+_2 states in 160,162Er are also strongly populated, with strengths in the range of 13% to 20% relative to the ground state population. The strength in 160Er is consistent with that observed in other N=92 isotones, and suggest a common structural feature, possibly related to shape coexistence and the role that the 11/2-[505] configuration is playing in the 0+_2 states in the N=90 isotones.