Study of Nuclei with S = -2

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The study of nuclear systems with strangeness (S) = -2 is quite important in order to understand the baryon-baryon interactions in an unified way and it will also give us a basis toward a new form of the nuclear matter such as strange quark matter. However the experimental study of S = -2 nuclear systems has been limited so far ; only two reports of the double-lambda(DL) hypernuclei since 1960's. We carried out two complementary experiments in order to create and identify DL hypernuclei by more than one order of magnitude than before ; one is E906 at BNL-AGS, where relatively light DL hypernuclei will be identified by observing two successive decaying pions with Cylindrical Detector Systems (CDS) and the other is to use a novel technique, i,e. a hybrid emulsion technique (KEK-PS E373). The analysis of E906 is at the final stage and we obtain interesting results ; we have succeeded to create more than a few tens of the lightest DL hypernuclei, ィイD14ィエD1HィイD2ΛΛィエD2. This is the first experiment with such high statistics and will open a new way towards the study of S = -2 nuclear systems with future high-intensity accelerators. We have also obtained the cross sections of Ξp elastic and Ξp -> ΛΛ. The analysis of E373 is under way and we will accumulate more data in the next April. We hope to eventually identify various species of DL hypernuclei with better statistics by one order of magnitude than before.