Fission of heavy hypernuclei formed in antiproton annihilation

Heavy hypernuclei are produced in the annihilation of antiprotons in ${}_{}{}^{238}{}_{}{}^{}\mathrm{U}$. The delayed fission of heavy hypernuclei and hypernuclei of fission fragments are observed by using the recoil-distance method in combination with measurement of secondary electron multiplicity. The lifetime of hypernuclei in the region of uranium is found to be (1.25±0.15)×${10}^{\mathrm{-}10}$ sec. It is observed that Λ hyperons predominantly stick to the heavier fission fragments. The yield of hypernuclei is found to be (7.4±1.7)×${10}^{\mathrm{-}3}$ per stopped antiproton. No coincidences with ${\mathit{K}}^{+}$ were found. Statistical and systematic errors on the number of events expected do not rule out this possibility.