Collective 2$^{+1}$ excitations in$^{206}$Po and$^{208,210}$Rn

In the present study, $B(E2, 2^{+1}\rightarrow 0^{+1})$ values have been measured in the$^{208,210}$Rn and$^{206}$Po nuclei through Coulomb excitation of re-accelerated radioactive beams in inverse kinematics at CERN-ISOLDE. These nuclei have been proposed to lie in, or at the boundary of the region where the seniority scheme should persist. However, contributions from collective excitations are likely to be present when moving away from the N=126 closed shell. Such an effect is confirmed by the observed increased collectivity of the $2^{+1}\rightarrow 0^{+1}$ transitions. Experimental results have been interpreted with the aid of theoretical studies carried out within the BCS-based QRPA framework.