A 32 cm hydrogen bubble chamber eexposed to a 16 GeV/c $\pi^{-}$ meson beam in March 1960. Magnetic field 15 KG

$\pi^{-} + p \rightarrow 4$ charged particles, probably $\pi$ mesons, plus a $\Lambda^{0}$ hyperon. The $\Lambda^{0}$ decay in $p + \pi^{-}$ can be seen