Decay of mass-separatedTl190andHg190

Radioactive sources containing ${}_{}{}^{190}{}_{}{}^{}\mathrm{Tl}$ and ${}_{}{}^{190}{}_{}{}^{}\mathrm{Hg}$ have been produced and mass separated with the University Isotope Separator on line to the Oak Ridge isochronous cyclotron. Multiscaled spectra of $\gamma$ rays, x rays, conversion electrons, and positrons were obtained, and $\gamma -\gamma$ and $\gamma$-x-ray coincidences were measured. Two isomers in ${}_{}{}^{190}{}_{}{}^{}\mathrm{Tl}$ decay have half-lives of 2.6 ± 0.3 min ($2^{-}$) and 3.7 ± 0.3 min ($7^{+}$). From $\beta$ decay endpoint energies the $7^{+}$ and $2^{-}$ isomers lie within 0.1 MeV of each other, but which is the ground state was not determined. Both isomers have ground-state $Q_{\mathrm{EC}}$ values of approximately 7 MeV. The $2^{-}$ level undergoes $\beta$ decay primarily to the $2^{+}$ states at 416.4 and 1099.9 keV in ${}_{}{}^{190}{}_{}{}^{}\mathrm{Hg}$, while the decay of the $7^{+}$ isomer feeds a number of different states with spins ranging from 5 to 9. We observed the $5^{-}$, $7^{-}$, and $9^{-}$ members of the previously identified structure of negative-parity states resulting from coupling of a rotation-aligned $i_{\frac{13}{2}}$ neutron with $3p_{\frac{3}{2}}$ and $2f_{\frac{5}{2}}$ neutrons. Some additional states having decays consistent with ($6^{-}$) and ($8^{-}$) assignments perhaps are candidates for less aligned members of the ${13/2}^{+}$ band coupled with $p_{\frac{3}{2}}$ and $f_{\frac{5}{2}}$ neutrons. The 20-min ${}_{}{}^{190}{}_{}{}^{}\mathrm{Hg}$ isotope decays approximately 65% of the time to a level at 171.5 keV, thus making it difficult to study other levels in ${}_{}{}^{190}{}_{}{}^{}\mathrm{Au}$. Four new states in ${}_{}{}^{190}{}_{}{}^{}\mathrm{Au}$ were definitely established, while several new ones were suggested by the present work. The populated levels are predominantly low spin and are fairly closely spaced. The $log\mathrm{ft}$ value for the transition to the 171.5 keV level is 5.7, so it is likely that this state has a spin and parity of $1^{+}$.