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The evolution of nuclear collectivity and structure in the region surrounding the doubly-magic nucleus $^{132}$Sn remains a central open question in nuclear structure physics. Recent shell-model calculations, employing realistic interactions, predict an enhancement of collectivity in the neighboring even-even isotopes of $^{132}$Sn [1]. Despite this, a long-standing discrepancy between experimental data for $^{130}$Sn and $^{134}$Sn and theoretical predictions persists [2]. To address this issue, two Coulomb excitation experiments were conducted at ISOLDE in 2023 and 2025. Post-accelerated radioactive ion beams, delivered by the HIE-ISOLDE accelerator at 4.4 MeV/u, were incident on $^{206}$Pb and $^{194}$Pt targets. The first excited states of $^{130}$Sn and $^{134}$Sn were selectively populated via safe Coulomb excitation. Deexciting $\gamma$ rays were detected with the highly efficient MINIBALL $\gamma$-ray spectrometer in coincidence with scattered particles. Results from the 2023 experiment provide new experimental B(E2) data that resolve the previously observed discrepancy between theory and experiment in $^{130}$Sn. This contribution will also include results concerning Coulomb excitation of the long-lived 7$^-$ isomer in $^{130}$Sn and present the current status of the analysis of the 2025 data for $^{134}$Sn.
[1] D. Rosiak \textit{et al.}, Phys. Rev. Lett. \textbf{121}, 252501 (2018).
[2] T. Togashi \textit{et al.}, Phys. Rev. Lett. \textbf{121}, 062501 (2018).