Observation of theΩ¯

We have observed an $\overline{\Omega }$ event. The $\overline{\Omega }$ is produced in the reaction $K^{+}d\to \overline{\Omega }\Lambda \Lambda p{\pi }^{+}{\pi }^{-}$ at $12 \frac{\mathrm{GeV}}{c}$, and decays via the mode $\overline{\Omega }\to \overline{\Lambda }{K}^{+}$. The fitted mass for this particle is $M_{\overline{\Omega }}=1673.1\mathrm{}\pm 1.0$ MeV. The $\overline{\Omega }$-production cross section is of the order of 0.1 μb.