Production of Heavy Unstable Particles by Negative Pions

Abstract

In addition to two previously discussed cloud-chamber examples of $V$-particle production by 1.5-Bev ${\ensuremath{\pi}}^{\ensuremath{-}}$ mesons from the Cosmotron, four further examples are discussed here. In two of the new examples a ${\ensuremath{\Lambda}}^{0}({{V}_{1}}^{0})$ and a ${\ensuremath{\vartheta}}^{0}({{V}_{4}}^{0})$ are seen to decay in a geometry indicating that they were produced together in a ${\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{-}p$ collision. A third example is best interpreted as production of a ${\ensuremath{\Lambda}}^{\ensuremath{-}}({{V}_{1}}^{\ensuremath{-}})$ together with a ${K}^{+}({{V}_{2}}^{+})$ by a ${\ensuremath{\pi}}^{\ensuremath{-}}$ colliding with a proton. A fourth example show a probable ${\ensuremath{\Lambda}}^{\ensuremath{-}}$ decaying into a ${\ensuremath{\pi}}^{\ensuremath{-}}$ and a neutron with a $Q$ value of about 130 Mev. A cross section of \ensuremath{\sim}1 millibarn for $V$-particle production is inferred from the number of ${\ensuremath{\pi}}^{\ensuremath{-}}\ensuremath{-}p$ collisions observed.