Nuclear Capture of NegativeKMesons in Emulsion

Abstract

Thirty stars produced by stopped negative $K$ mesons were found by area scanning in pellicles exposed to the Berkeley Bevatron accelerator. The ratio $\frac{K^{-}}{{\pi }^{-}}$ at 90° to the incident 6.2-Bev proton beam was found to be (0.76±0.11)×${10}^{-4\mathrm{}}$ for an average momentum of 240 Mev/c. In four cases, charged hyperons were emitted from the stars, of which three are interpreted as ${\Sigma }^{+}$ hyperons and one as a ${\Sigma }^{-}$ hyperon. In two additional cases the stopped $K^{-}$ meson produced a hyperfragment. From 8 of the 30 stars, charged $\pi$ mesons were emitted. The 30 events are all consistent with the production of a neutral or a charged hyperon upon the absorption of the $K^{-}$ meson. The production ratio of $\Sigma$ hyperons to ${\Lambda }^0$ hyperons is estimated to be of the order of $\frac{9}{21}$.