Electromagnetic Moments of Radioactive 136 Te and the Emergence of Collectivity 2p ⊕ 2n outside of Double-Magic 132 Sn
Radioactive 136 Te has two valence protons and two valence neutrons outside of the 132 Sn double shell closure, providing a simple laboratory for exploring the emergence of collectivity and nucleon- nucleon interactions. Coulomb excitation of 136 Te on a titanium target was utilized to determine an extensive set of electromagnetic moments for the three lowest-lying states, including B(E2;0$+\atop{1}$→ 2$+\atop{1}$ ), Q(2$+\atop{1}$ ), and g(2$+\atop{1}$ ). The results indicate that the first-excited state, 2$+\atop{1}$ , composed of the simple 2p ⊕ 2n system, is prolate deformed, and its wave function is dominated by neutron degrees of freedom, but not to the extent previously suggested. It is demonstrated that extreme sensitivity of g(2$+\atop{1}$) to the proton and neutron contributions to the wave function provides unique insight into the nature of emerging collectivity, and g(2$+\atop{1}$ ) was used to differentiate among several state-of-the-art theoretical calculations. Finally, our results are best described by the most recent shell model calculations.