Cascade {gamma} decay in the {sub {lambda}}{sup 7}Li hypernucleus

In a \\ensuremath{\\gamma}-ray spectroscopy experiment with the $({K}^{\\ensuremath{-}},{\\ensuremath{\\pi}}^{\\ensuremath{-}})$ reaction on a $^{10}\\mathrm{B}$ target, we have observed the $7/{2}^{+}\\ensuremath{\\rightarrow}5/{2}^{+}$ spin-flip $M1$ transition in ${}_{\\ensuremath{\\Lambda}}^{7}\\text{Li}$ via \\ensuremath{\\gamma}-\\ensuremath{\\gamma} coincidence with the $5/{2}^{+}\\ensuremath{\\rightarrow}1/{2}^{+}E2$ transition. This is the first successful $\\ensuremath{\\gamma}\\text{\\ensuremath{-}}\\ensuremath{\\gamma}$ coincidence measurement for hypernuclei. The measured $M1 \\ensuremath{\\gamma}$-ray energy is $470.8\\ifmmode\\pm\\else\\textpm\\fi{}1.9$(stat)$\\ifmmode\\pm\\else\\textpm\\fi{}0.6$(syst) keV. The spacing of the $7/{2}^{+},5/{2}^{+}$ doublet is consistently explained using the strengths of the spin-spin, \\ensuremath{\\Lambda}-spin-orbit, and tensor interactions obtained from previous \\ensuremath{\\gamma}-spectroscopy experiments.