Lifetime measurements have been made in the neutron-deficient nucleus Te-109 using the coincident recoil distance Doppler-shift method. The experimental B(E2) values have been compared with state-of-the-art shell-model calculations using the monopole-corrected realistic charge-dependent Bonn nucleon-nucleon potential. Lifetimes in the vh(11/2) band are consistent with an interpretation based on the deformation driving properties of a single valence neutron outside of the even-even tellurium core and highlight the unexpected presence of collective behavior as the N = 50 shell closure is approached. Lifetime measurements for the low-lying positive-parity states also appear to correlate well with shell-model calculations. In addition, a comparison with the proton-unbound nucleus I-109 suggests that the presence of a single decoupled valence proton affects the total measured B(E2) strengths in a manner that is not currently well understood.
QC 20121019