Experimental observation of the Σ hypernuclei, 6sub(Σ)H and 16sub(Σ)C

The hypernuclei sub(Σ)6H and sub(Σ)16C were observed by the (K-, π+) reaction on targets of 6Li and liquid O, r-spectively, at 713 MeV/c incident K- momentum. Structure is seen in sub(Σ)6H which may be interpreted in terms of particle-hole excitations similar to the previously observed states in sub(Λ)6Li. The inability to resolve individual Σ hypernuclear levels in sub(Σ)16C, due in part to the excitation of non-coherent states as a result of the large momentum transfer of about 130 MeV/c, precludes the extraction of the Σ-nucleus spin-orbit potential strength. The Σ-nucleus well depth appears to be 7 to 10 MeV less than that for the Λ. (orig.)