Cosmic-Ray Protons at 3.4 Kilometers

Abstract

A magnetic cloud chamber and an appropriate arrangement of coincidence and anticoincidence Geiger counters were used to photograph tracks of charged particles with ranges of 0.4 to 15 cm and 0.4 to 30 cm of lead. The momentum intervals corresponding to these range intervals are sufficiently different for protons and mesons that there resulted a large momentum interval in which only protons were stopped due to ionization losses. At higher momenta, most of the protons were stopped by nuclear interaction because of the large thicknesses of absorber used. At lower momenta, where both protons and mesons were stopped, the protons were distinguished by track density.