Double-Λ Hypernuclei via the Ξ− Hyperon Capture at Rest Reaction in a Hybrid Emulsion

We have obtained nearly one thousand events of the Ξ− hyperon captured at rest in nuclear emulsion. Among them, production and decay of double-Λ hypernuclei was successfully found and analyzed for five events which correspond to five nuclear species with double strangeness. Preliminary results are discussed for the binding energy and interaction energy of two Λ hyperons. By comparison with older data, the excitation energy of the BeΛΛ10 nucleus is also discussed. A new experiment,which is expected to provide 10 times more double-strangeness events than before, is introduced.