Precision excited-state lifetime measurements of neutron-rich Li isotopes

Recent successes with \textit{ab initio} calculations are allowing increasingly subtle nuclear phenomena to be investigated, such as $\Delta$-isobar and meson exchange effects which are necessary to reproduce $M1$ properties of nuclei. In order to guide such explorations, precise experimental data are required to discriminate between various theoretical descriptions. The lithium isotopes, which are dominated by $M1$ spin-flip transitions, provide an ideal testing ground for such studies. We have performed lifetime measurements of the excited states of $^{7,8}$Li, as well as explored the feasibility of such an experiment on $^9$Li, to provide precise data on the $M1$ transition matrix elements in these nuclei. The experiment used the Doppler Shift Attenuation Method to measure the lifetimes at TRIUMF with TIGRESS, with the excited states populated by inverse $(d,p)$ reactions. Preliminary results from the analysis will be presented.