High-spin states in even Hg nuclei and rotation alignment inHg198

High-spin states in even Hg isotopes populated in ($\alpha , \mathrm{xn}$) reactions were investigated by in-beam $\gamma$-ray and conversion electron spectroscopy. Several new excited states in the ground state band of ${}_{}{}^{198}{}_{}{}^{}\mathrm{Hg}$ and in the negative parity bands of ${}_{}{}^{198,200}{}_{}{}^{}\mathrm{Hg}$ were identified. Half-lives of a number of levels in ${}_{}{}^{194,196,198}{}_{}{}^{}\mathrm{Hg}$ were measured. In particular we obtain $T_{\frac{1}{2}}=1.38\mathrm{}\left(4\right)\mathrm{} \mathrm{and} 1.85\left(16\right)\mathrm{}$ ns for the ${12}^{+}$ and ${10}^{+}$ states in ${}_{}{}^{198}{}_{}{}^{}\mathrm{Hg}$, respectively. Intrinsic quadrupole moments $Q_0$ derived from these data and the $B(E2,0^{+}\to 2^{+})$ agree within the limits of error. These data together with the excitation energies of the ground state band are interpreted within the rotationalignment model.