Lambda Hypernuclei via gamma-Ray Spectroscopy

High precision gamma-ray spectroscopy of Lambda hypernuclei with a germanium detector array, Hyperball, has revealed fine structure of various p-shell Lambda hypernuclei. From accumulated data the strengths of all the spin-dependent components in the LambdaN interaction have been extracted, which play essential roles to improve baryon-baryon interaction models. The hypernuclear shrinking effect was confirmed from measurement of a B(E2) value in (7_Lambda) Li. In the J-PARC facility, intense kaon beams and a new generation Ge detector array will allow us to investigate baryon properties in nuclei and impurity effects, as well as to further study the hyperon-nucleon interactions.