A recent experimental progress of strangeness nuclear physics is reviewed from viewpoint of hyperon-nucleon (YN) and hyperon-hyperon (YY) interactions. Detailed level structure of Λ hypernuclei has been studied by γ-ray spectroscopy technique using a germanium detector array as well as an NaI counter array, which determined the strengths of the ΛN spin-spin and spin-orbit interactions. In the emulsion-counter hybrid experiment, a double Λ hypernucleus ΛΛ 6 He was observed and the strength of the ΛΛ interaction was unambiguously derived. As for the ∑N interaction, a recent 28Si(π-, K+) spectrum suggests a strongly repulsive ∑-nucleus potential, while the spin-orbit force of ∑ is being studied by a ∑p scattering experiment.
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