Stars Produced byπ−Capture in a Hydrogen Bubble Chamber Containing Dissolved Helium

One-pronged stars produced by ${\pi }^{-}$ capture in a hydrogen bubble chamber containing dissolved helium have been investigated. The distribution of prong lengths in the interval 0.029 to 0.64 g/${\mathrm{cm}}^2$ is presented. About one-third of the prongs in this interval are found to have a unique range corresponding to tritons from the reaction ${\pi }^{-}+{\mathrm{He}}^4\to {\mathrm{He}}^3+n$. Some prongs lying beyond the triton peak are identified as protons from the reaction ${\pi }^{-}+{\mathrm{He}}^4\to {\mathrm{H}}^{\prime }+3n$. The fraction of pions producing stars is found to be approximately equal to the helium concentration.