Analysis of a High-Energy Cosmic-Ray Shower. I. Soft Component and Trident Process

An analysis is presented of the soft component arising from a high energy nuclear shower (∼3×${10}^{13}$ ev) observed in stripped emulsion. The chief results obtained are: (1) The production ratio of neutral $\pi$ mesons to charged shower particles is 0.50±0.11; (2) the lifetime of the neutral $\pi$ meson is found to be ($1_{-0.5\mathrm{}}^{+1\mathrm{}}$) × ${10}^{-14\mathrm{}}$ sec; (3) the mean free path for direct electron pair production by high-energy electrons is found to be 4.4 and 1.1 radiation units for electrons in the energy intervals 1 to 10 Bev and 10 to 100 Bev, respectively.