  Missing mass spectroscopy with the $(e,e^{\prime}K^{+})$ reaction was
performed at Jefferson Laboratory's Hall C for the neutron rich $\Lambda$
hypernucleus $^{9}_{\Lambda}{\rm Li}$. The ground state energy was obtained to
be $B_{\Lambda}^{\rm g.s.}=8.84\pm0.17^{\rm stat.}\pm0.15^{\rm sys.}~{\rm MeV}$
by using shell model calculations of a cross section ratio and an energy
separation of the spin doublet states ($3/2^{+}_1$ and $5/2^{+}_1$). In
addition, peaks that are considered to be states of [$^{8}{\rm
Li}(3^{+})\otimes s_{\Lambda}=3/2^{+}_{2}, 1/2^{+}$] and [$^{8}{\rm
Li}(1^{+})\otimes s_{\Lambda}=5/2^{+}_{2}, 7/2^{+}$] were observed at
$E_{\Lambda}({\rm no.~2})=1.74\pm0.27^{\rm stat.}\pm0.11^{\rm sys.}~{\rm MeV}$
and $E_{\Lambda}({\rm no.~3})=3.30\pm0.24^{\rm stat.}\pm0.11^{\rm sys.}~{\rm
MeV}$, respectively. The $E_{\Lambda}({\rm no.~3})$ is larger than shell model
predictions by a few hundred keV, and the difference would indicate that a
${\rm ^{5}He}+t$ structure is more developed for the $3^{+}$ state than those
for the $2^{+}$ and $1^{+}$ states in a core nucleus $^{8}{\rm Li}$ as a
cluster model calculation suggests.

Nuclear Experiment