101. Properties of Heavy Unstable Particles Produced by 1.3-Bevπ−Mesons
- Author
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J. Leitner, M. Chretien, R. Budde, J. Steinberger, N. P. Samios, and M. Schwartz
- Subjects
Physics ,Nuclear reaction ,Pion ,Angular distribution ,Meson ,Angular correlation ,General Physics and Astronomy ,Production (computer science) ,Statistical analysis ,Atomic physics ,Energy (signal processing) - Abstract
A propane bubble chamber has been exposed to a ${\ensuremath{\pi}}^{\ensuremath{-}}$ beam of 1.3-Bev kinetic energy. The reactions ${\ensuremath{\pi}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}{\ensuremath{\Sigma}}^{\ensuremath{-}}+{K}^{+},$ ${\ensuremath{\pi}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}{\ensuremath{\Lambda}}^{0}+{\ensuremath{\theta}}^{0},$ ${\ensuremath{\pi}}^{\ensuremath{-}}+p\ensuremath{\rightarrow}{\ensuremath{\Sigma}}^{0}+{\ensuremath{\theta}}^{0},$ can be experimentally distinguished from carbon events. Results based on the first 55 such events are presented. The center-of-mass production distribution of the ${\ensuremath{\Sigma}}^{\ensuremath{-}}$ is peaked forward, that of the ${\ensuremath{\Lambda}}^{0}$ backward. No large anisotropies in the angular correlation of production and decay were found, so that we have no evidence for spin in excess of \textonehalf{} for any of the three particles: ${\ensuremath{\Sigma}}^{\ensuremath{-}}$, ${\ensuremath{\Lambda}}^{0}$, or ${\ensuremath{\theta}}^{0}$. A study of the relative abundance of single and double $V$ production indicates that both ${\ensuremath{\Lambda}}^{0}$ and ${\ensuremath{\theta}}^{0}$ have either long-lived "states" or neutral decay modes. A statistical analysis gives ${\overline{\ensuremath{\alpha}}}_{{\ensuremath{\Lambda}}^{0}}={{0.3}_{\ensuremath{-}0.12}}^{+0.15}$, ${\overline{\ensuremath{\alpha}}}_{{\ensuremath{\theta}}^{0}}={{0.3}_{\ensuremath{-}0.12}}^{+0.19}$, for the normal charged decay probabilities (${\ensuremath{\Lambda}}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}+p$; ${\ensuremath{\theta}}^{0}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{+}+{\ensuremath{\pi}}^{\ensuremath{-}}$) of the ${\ensuremath{\Lambda}}^{0}$ and ${\ensuremath{\theta}}^{0}$, respectively. One event was analyzed to obtain the energy released in ${\ensuremath{\Sigma}}^{\ensuremath{-}}$ decay. ${\ensuremath{\Sigma}}^{\ensuremath{-}}\ensuremath{\rightarrow}{\ensuremath{\pi}}^{\ensuremath{-}}+n+Q$; $Q=118\ifmmode\pm\else\textpm\fi{}2.6$ Mev. The ${\ensuremath{\Sigma}}^{\ensuremath{-}}$ lifetime on the basis of 16 decays is (${1.4}_{\ensuremath{-}0.5}^{+1.6}$)\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}10}$ sec.
- Published
- 1956