Proton-Meson Analysis of the Cosmic Radiation at 3.4 Kilometers

A magnetic cloud chamber has been used along with an appropriate arrangement of coincidence and anti-coincidence counters to photograph tracks of those charged particles at 3.4 km altitude having ranges of 0.5 to 5, 5.5 to 15, and 15 to 25 cm in lead. An additional 2.5 cm lead was used above the chamber to remove showers. Plotting in each case the distribution in momentum of positive and negative particles there is shown a clear resolution into protons and mesons. It is found that about twice as many protons as mesons stop in lead at ranges between 2.5 and 7.5 cm lead. The meson intensity (differential range intensity) is found to be 6.1±0.06×${10}^{-6\mathrm{}}$ particles per (g sec sterad) of air at 60 g air range and 12.0±1.0×${10}^{-6\mathrm{}}$ at 125 g air range.