Nuclear structure of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">Th</mml:mi><mml:mprescripts/><mml:none/><mml:mrow><mml:mn>229</mml:mn></mml:mrow></mml:mmultiscripts></mml:math>

Lifetimes of excited states in $^{229}\mathrm{Th}$, populated in the \ensuremath{\beta} decay of $^{229}\mathrm{Ac}$, have been measured using the advanced time-delayed $\ensuremath{\beta}\ensuremath{\gamma}\ensuremath{\gamma}$(t) method. Half-lives of 14 states have been determined including 11 of them for the first time. Twenty-seven new \ensuremath{\gamma} lines have been introduced into the \ensuremath{\beta}-decay scheme of $^{229}\mathrm{Ac}$ based on results of $\ensuremath{\gamma}\ensuremath{\gamma}$ coincidence measurements. Reduced transition probabilities have been determined for more than 70 \ensuremath{\gamma} transitions in $^{229}\mathrm{Th}$. Average $|{D}_{0}|$ values of 0.029(1), 0.077(3), and 0.024(5) $e$ fm have been deduced for the lowest ${K}^{\ensuremath{\pi}}=1/{2}^{\ifmmode\pm\else\textpm\fi{}},3/{2}^{\ifmmode\pm\else\textpm\fi{}}$, and $5/{2}^{\ifmmode\pm\else\textpm\fi{}}$ parity partner bands, respectively. Excited states in $^{229}\mathrm{Th}$ and experimental transition rates have been interpreted within the quasiparticle-plus-phonon model. The half-life of the 3.5-eV, $3/{2}^{+}$ isomeric state is predicted to be about 10 h. Potential energy surfaces on the (${\ensuremath{\beta}}_{2},{\ensuremath{\beta}}_{3}$) plane for the lowest single quasiparticle configurations in $^{229}\mathrm{Th}$ have been calculated using the Strutinsky method.