Production of twin Λ-hypernuclei from Ξ− hyperon capture at rest

Abstract

A hybrid emulsion experiment was carried out to study double-strangeness nuclei produced via Ξ − hyperon capture at rest with the expectation of ten times larger statistics than previous experiments. We have analyzed 5% of the total emulsion and found one “twin-hypernuclei” event involving the emission of two single- Λ hypernuclei and a nuclear fragment from a Ξ − hyperon stopping point. The event is interpreted as the decay of a Ξ −+ 14 N atomic system to 5 Λ He+ 5 Λ He+ 4 He+ neutron . The species of the Ξ −-atom and the fragmentation products are uniquely identified for the first time for twin-hypernuclei events. Combined with the results from a past hybrid-emulsion experiment, one double- Λ hypernucleus and three twin-hypernuclei events have been found from Ξ − captures on light emulsion nuclei. The ratio of the detected rate of double- Λ hypernuclei to that of twin-hypernuclei is compared with theoretical estimates.