A probable example of the reaction: π−+p=K++K−+n

An event is described in which a fast singly charged particle, produces a star from which the only charged particles emitted are a negative K-meson and another particle of ∼ 1000 electronic masses. The interest of the event is due to the fact that this is the first case in which a mechanism of creation of a negative K-meson can be specified with a good degree of reliability. The event is shown to be in agreement with the selection rules resulting from associated production ideas.