  An experiment with a newly developed high-resolution kaon spectrometer (HKS)
and a scattered electron spectrometer with a novel configuration was performed
in Hall C at Jefferson Lab (JLab). The ground state of a neutron-rich
hypernucleus, He 7 Lambda, was observed for the first time with the (e,e'K+)
reaction with an energy resolution of ~0.6 MeV. This resolution is the best
reported to date for hypernuclear reaction spectroscopy. The he 7 Lambda
binding energy supplies the last missing information of the A=7, T=1
hypernuclear iso-triplet, providing a new input for the charge symmetry
breaking (CSB) effect of \Lambda N potential.
