The Electronic Component at Low Altitudes Produced byπ-Meson Decay

The intensity of the electronic component at low altitudes produced by $\pi$-meson decay (designated as the $E_{\pi }$ component) has been obtained as a function of zenith angle and altitude by subtracting from the experimentally observed soft component those electrons arising from the collision and decay processes of $\mu$-mesons (designated as $E_{\mu }$ electrons). Extensive auxiliary studies of the corrections required in such soft component studies are described, and experimental requirements are stated for a precise telescopic study of the soft component. In particular, it is shown that the usual method of correcting a Geiger counter telescope for side showers is incorrect, and also that the effect of wall-generated secondaries should be considered. It is shown that the $E_{\pi }$ component of energy greater than 30 Mev can be represented as a function of zenith angle $\theta$ and atmospheric depth $h$ by the expression $I(E_{\pi },h,\theta )=0.70\mathrm{}\exp (-\frac{h}{160cos\theta }){\mathrm{cm}}^{-2\mathrm{}}invsec{\mathrm{sterad}}^{-1\mathrm{}},$ for $\theta <~{60}^{\circ }$ and $h>~700$ g ${\mathrm{cm}}^{-2\mathrm{}}$.