Evidence of Nuclear Structures fromK−-Meson Absorption

The characteristics of the multinucleon capture of $K^{-}$ mesons in nuclei have been investigated in both normal and water-soaked $G5\mathrm{}$ nuclear emulsion. It has been found that the emission of fast (⋝ 60 MeV) hyperons is more often associated with $K^{-}$ captures in light (C,N,O) than in heavy (Ag,Br) nuclei. Further, considering the relative absorptions of $\Sigma$ hyperons in the parent nucleus in which they are produced, we inferred that the rate of multinucleon $K^{-}$ absorptions is approximately the same for all nuclei of nuclear emulsion and corresponds to ∼17% of all $K^{-}$ absorptions at rest. From those events which can be definitely assigned to interactions in light nuclei, by virtue of energy and momentum conservation, it was found that the reaction $K^{-}+(n, n)\to {\Sigma }^{-}+n$ is of comparable intensity with the reaction $K^{-}+(n, p)\to {\Sigma }^{-}+p$, and that in light nuclei, the major mode of multinucleon $K^{-}$ absorption in C,N,O appears to be on a pair of nucleons in an $\alpha$-particle cluster. Comparison of the characteristics of the $K^{-}$ multinucleon absorptions in light and heavy nuclei shows that $\alpha$-particle clusters are less likely to be involved in (Ag,Br) than in (C,N,O). An attempt to estimate the nuclear pair correlation function was also made.