Shape coexistence in the neutron-deficient lead region: A systematic study of lifetimes in the even-even ${}^{188-200}$Hg with GRIFFIN

Abstract

Lifetimes of $2_1^{+}$ and $4_1^{+}$ states, as well as some negative-parity and non-yrast states, in ${}^{188-200}$Hg were measured using ${\hat{I}}^3-{\hat{I}}^3$ electronic fast timing techniques with the LaBr${}_3$(Ce) detector array of the GRIFFIN spectrometer. The excited states were populated in the $ε/β^+$-decay of $J^{\ddot{I}}€=7^{+}/2^{-}$ ${}^{188-200}$Tl produced at the TRIUMF-ISAC facility. The deduced B(E2) values are compared to different interacting boson model predictions. The precision achieved in this work over previous ones allows for a meaningful comparison with the different theoretical models of these transitional Hg isotopes, which confirms the onset of state mixing in ${}^{190}$Hg.