Shape coexistence inHg186and the decay ofTl186

Details of the identification of ${}_{}{}^{186}{}_{}{}^{}\mathrm{Tl}$ and its decay to ${}_{}{}^{186}{}_{}{}^{}\mathrm{Hg}$ as investigated with an isotope separator are presented. Conversion electrons, $\gamma$, $\gamma -\gamma$, and $e-\gamma$ studies establish two bands in ${}_{}{}^{186}{}_{}{}^{}\mathrm{Hg}$; one built on a near-spherical ground state and one on a more strongly deformed shape with a band head at 522 keV. The levels are discussed in the framework of recent theoretical calculations.