Lifetime Measurements of Trapped $^{232}$Th$^{3+}$

In recent years, there has been considerable interest in the low lying nuclear isomer state of $^{229}$Th which is only several eV above the nuclear ground state [1]. To date, several groups are taking a variety of approaches to finding and exciting this unique state [2], including the use of trapped Th$^{3+}$ ions. Despite this attention, few precise measurements have been made of atomic lifetimes. In this work we present experiments to measure the $6D_{3/2}$ and $6D_{5/2}$ states using laser cooled $^{232}$Th$^{3+}$ confined in a linear Paul trap.\\[4pt] [1] E.~Peik and Chr.~Tamm, \textit{Europhys. Lett.} \textbf{61}, 181 (2003); V.~V.~Flambaum, \textit{Phys. Rev. Lett.} \textbf{97}, 092502 (2006); B.~R.~Beck \textit{et al.}, \textit{Phys. Rev. Lett.} \textbf{98}, 142501 (2007).\\[0pt] [2] W.~G.~Rellergert \textit{et al.}, \textit{Phys. Rev. Lett.} \textbf{104}, 200802 (2010); S.~G.~Porsev \textit{et al.}, \textit{Phys. Rev. Lett.} \textbf{105}, 182501 (2010); C.~J.~Campbell \textit{et al.}, \textit{Phys. Rev. Let.} \textbf{106}, 223001 (2011).