Two Hyperfragments from NegativeK-Particle Capture and the Mass of the NegativeKParticle

Abstract

Two hyperfragments are described which have been found from 81 negative $K$-particle interactions at rest and in flight. Event 35 was identified as a $K^{-}$ capture in carbon which emitted a ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{Li}_{}^7{}_{}{}^{}$ hyperfragment that decayed into a ${\pi }^{-}$ meson and a ${\mathrm{Be}}^7$ fragment. The binding energy of the $\Lambda$ hyperon in ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{Li}_{}^7{}_{}{}^{}$ was found to be 4.4±0.7 Mev. The mass of the negative $K$ particle which was captured in this reaction was found to be 966.2±5.0 electron masses. In Event 71, a negative $K$ particle was captured in a light nucleus. Four charged particles and a ${\pi }^{-}$ meson and a hyperfragment, ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^4{}_{}{}^{}$, left the $K^{-}$ ending. The ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^4{}_{}{}^{}$ decayed into a proton, a ${\pi }^{-}$ meson, and a ${\mathrm{He}}^3$ fragment. The binding energy of the $\Lambda$ hyperon in ${}_{\Lambda }{}^{}{}_{}{}^{}\mathrm{He}_{}^4{}_{}{}^{}$ was found to be 1.5±0.6 Mev.