Observation and Analysis ofK−Interactions

Abstract

In nuclear emulsions, 289 ${K}^{\ensuremath{-}}$ mesons were observed. The mass and lifetime of ${K}^{\ensuremath{-}}$ mesons is the same as that of ${K}^{+}$ mesons. The ${K}^{\ensuremath{-}}$ mean free path in nuclear emulsion is geometric. Charge-exchange scattering and inelastic ${K}^{\ensuremath{-}}$-nucleus scattering are rare. Positive hyperons are emitted in 8% of ${K}^{\ensuremath{-}}$ capture stars, negative hyperons in about 9%, hyperfragments in 5%. It is estimated that a ${\ensuremath{\Lambda}}^{0}$ is trapped without production of a visible hyperfragment in an additional 8%. A ${K}^{\ensuremath{-}}$ is captured by one nucleon with formation of a $\ensuremath{\Sigma}$ hyperon and a pion in about 0.77 of the cases, with creation of a ${\ensuremath{\Lambda}}^{0}$ and a pion in approximately 0.18 of the events. Capture by two nucleons occurs in roughly 0.05 of the cases. From a comparison of production and emission frequencies of $\ensuremath{\Sigma}$ hyperons it is concluded that an attractive nuclear potential for $\ensuremath{\Sigma}$ hyperons must be less than 20 Mev. Limits for the mean free paths for ordinary scattering, for charge-exchange scattering, and for absorption of $\ensuremath{\Sigma}$ hyperons in nuclear matter are given. The trapping of ${\ensuremath{\Lambda}}^{0}$ hyperons in nuclei is discussed.