Electromagnetic Moments of Radioactive 136Te and the Emergence of Collectivity 2p ⊕ 2n outside of Double-Magic 132Sn

Radioactive 136Te has two valence protons and two valence neutrons outside of the 132Sn double shell closure, providing a simple laboratory for exploring the emergence of collectivity and nucleon- nucleon interactions. Coulomb excitationof 136Te 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 prolatedeformed, 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.