Spectroscopy of 188Hg Following the β+/EC Decay of 188,188mTl
The structure of 188Hg has been studied via the β+/EC decay of 188Tl with the Gamma Ray Infrastructure For Fundamental Investigations of Nuclei (GRIFFIN) spectrometer at the Isotope Separator and Accelerator (ISAC) radioactive ion beam facility at TRIUMF. Combining measurements of internal conversion electrons, γ rays, γ-conversion electron and γ-γ coincidences, a detailed level scheme was constructed involving 280 transitions between 137 excited states. Gamma-gamma angular correlations were measured to assign spins and determine mixing ratios, δ, for transitions of mixed multipolarities. These mixing ratios, together with the measured internal conversion coefficients, α, allowed the electric monopole, E0, components of several Jπ → Jπ transitions to be determined. The lowest Jπ = 3− state was firmly identified for the first time in the neutron deficient Hg isotopes, and several new structures with possible “K = 0”, “K = 2” and “K = 4” bandheads also proposed. These results provide new insights into the mixing of shape coexisting structures in 188Hg.