High-Precision γ-Ray Spectroscopy of Λ Hypernuclei

Abstract

The γ-ray spectroscopy study of Λ hypernuclei is reviewed, focusing on a series of experiments for high-precision γ-ray measurement using dedicated germanium (Ge) detector arrays. γ transitions from various Λ hypernuclei in the mass range of A = 4 − 19 were observed, and precise data of their level energies were used to extract the strengths of the spin-spin, spin-orbit, and tensor components of the ΛN interaction. γ-ray data for $$^4_\Lambda $$ He confirmed existence of a large effect of charge symmetry breaking (CSB) in Λ hypernuclei. A B(E2) value for a transition in $$^7_\Lambda $$ Li confirmed “shrinking effect” of hypernuclei. Future plans of hypernuclear γ-ray spectroscopy experiments, including a measurement of a B(M1) value for a Λ-spin-flip transition, are discussed.