Production of Hyperfragments by the Interactions of 1.5-GeV/c $K^{-}$ Mesons in Lithium-Loaded Emulsions

Hyperfragment production by some 31 000 interactions of 1.5-GeV/c $K^{-}$ mesons in Lithium-loaded $K5\mathrm{}$ nuclear emulsions has been studied and compared with data from 0.8-GeV/c and existing data from 1.5-GeV/c $K^{-}$ interactions in normal emulsions. The study of the prong number distributions of the hyperfragment parent stars provides a sensitive method for determining the production rates of hyperfragments by $K^{-}$ interactions with light ($C, N, 0$) and heavy (Ag,Br) emulsion nuclei; these production rates are found to be (0.66±0.11)% and (5.20±0.20)%, respectively. An appreciable proportion of mesonic hyperfragments ($Z<\mathrm{}6\mathrm{}$) and ${\mathrm{Li}}^8$ fragments have very short ranges ($R_{\mathrm{HF}}\le 10$ μ); this fact indicates the possibility of contaminations of "light" hypernuclides among the assumed mesic spallation hyperfragments. The predominant part of the hyperfragment production stars which shows the emission of "short" prongs involves the disintegration of heavy nuclei, thus indicating that Coulomb-barrier criteria cannot be used in discriminating among light or heavy hyperfragment parent stars at high $K^{-}$ momenta. No double hyperfragment was observed. One $K^{-}$ interaction emitted two hyperfragments decaying nonmesically. The ${\pi }^{+}$ decay of a ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^4{}_{}{}^{}$ hyperfragment has been found. An estimate of the branching ratio $R$ of the ${\pi }^{+}$ decay and ${\pi }^{-}$ decay modes for the ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^4{}_{}{}^{}$ hypernucleus gives $R\le (2.7\mathrm{}\pm 1.1)\%$.