Measured Magnetic Moments and Shape Coexistence in the Neutron-Deficient NucleiP184,186,188t

A novel implantation-decay technique has been employed to measure the magnetic moments of the $2_1^{+}$ states in the neutron-deficient nuclei ${}^{184}\mathrm{Pt}$, ${}^{186}\mathrm{Pt}$, and ${}^{188}\mathrm{Pt}$. The magnetic moment systematics for the even Pt isotopes now extend from ${}_{78}^{184}{\mathrm{Pt}}_{106}$ to ${}_{78}^{198}{\mathrm{Pt}}_{120}$, spanning the upper half of the valence neutron shell. Despite the prolate-to-oblate shape transition near $A=190\mathrm{}$, they remain remarkably constant. The $g\left(2_1^{+}\right)$ values for ${}^{184,186,188}\mathrm{Pt}$ are consistent with shape-coexistence models in which the deformed configuration has a larger effective number of valence protons than the less-deformed configuration.