Production of Heavy Unstable Particles by Negative Pions

In addition to two previously discussed cloud-chamber examples of V-particle production by 1.5-Bev π^- mesons from the Cosmotron, four further examples are discussed here. In two of the new examples a Λ⁰(V₁⁰) and a ϑ⁰(V₄⁰) are seen to decay in a geometry indicating that they were produced together in a π^--p collision. A third example is best interpreted as production of a Λ^-(V₁^-) together with a K⁺(V₂⁺) by a π^- colliding with a proton. A fourth example show a probable Λ^- decaying into a π^- and a neutron with a Q value of about 130 Mev. A cross section of ~1 millibarn for V-particle production is inferred from the number of π^--p collisions observed.