Coulomb-excitation experiments to study electromagnetic properties of radioactive even-even Hgisotopes were performed with 2.85 MeV=nucleon mercury beams from REX-ISOLDE. Magnitudes andrelative signs of the reduced E2 matrix elements that couple the ground state and low-lying excited states in182−188Hg were extracted. Information on the deformation of the ground and the first excited 0þ states wasdeduced using the quadrupole sum rules approach. Results show that the ground state is slightly deformedand of oblate nature, while a larger deformation for the excited 0þ state was noted in 182;184Hg. The resultsare compared to beyond mean field and interacting-boson based models and interpreted within a two-statemixing model. Partial agreement with the model calculations was obtained. The presence of two differentstructures in the light even-mass mercury isotopes that coexist at low excitation energy is firmlyestablished.
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