A<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>V</mml:mi></mml:math>-Decay Event with a Heavy Negative Secondary, and Identification of the Secondary<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>V</mml:mi></mml:math>-Decay Event in a Cascade

Abstract

Two cosmic-ray decay events have been photographed in a cloud chamber under conditions that yield mass values from combined magnetic-field momentum measurements and ionization measurements from droplet counting. A method has been developed for assigning meaningful probable errors to the ionization measurements. The first event is interpreted as the decay of a neutral $V$ particle into a positive $\ensuremath{\pi}$ meson and a negative particle of mass $1850\ifmmode\pm\else\textpm\fi{}250{m}_{e}$. On the assumption of a two-body decay, the $Q$ value for the decay is 11.7\ifmmode\pm\else\textpm\fi{}4 Mev. The second event is a cascade decay that can be summarized by the following reaction: ${{Y}^{\ensuremath{-}}\ensuremath{\rightarrow}67\ifmmode\pm\else\textpm\fi{}12 \mathrm{Mev}+{\ensuremath{\pi}}^{\ensuremath{-}}+{\ensuremath{\Lambda}}^{0}}{\ensuremath{\searrow}}{40\ifmmode\pm\else\textpm\fi{}13 \mathrm{Mev}+{\ensuremath{\pi}}^{\ensuremath{-}}+p.}$ The proton of the ${\ensuremath{\Lambda}}^{0}$ decay is identified by a measured mass of $2050\ifmmode\pm\else\textpm\fi{}350{m}_{e}$. On the assumption of a twobody decay, the mass of the primary $V$ particle is $2600\ifmmode\pm\else\textpm\fi{}34{m}_{e}$.