Further Results from the Study of Sea-Level Penetrating Showers

Abstract

Thirty-five non-ionizing link showers (produced at a 17-g/${\mathrm{cm}}^{2}$ Pb plate) associated with sea-level penetrating showers are presented. These have their axes oriented toward the origins of the penetrating showers and are believed to be cascade electronic showers initiated by high energy photons, which are probably produced from the decay of ${\ensuremath{\pi}}^{0}$ mesons among the penetrating shower particles. The size distribution of these showers is given showing a spread from 2 to 20 particles per shower. The angular distribution of their axes with respect to the penetrating shower axes is also approximately determined.Showers particles (of the penetrating showers) scattered by Be and Pb at angles greater than 10\ifmmode^\circ\else\textdegree\fi{}, 15\ifmmode^\circ\else\textdegree\fi{}, 20\ifmmode^\circ\else\textdegree\fi{}, 30\ifmmode^\circ\else\textdegree\fi{}, and 40\ifmmode^\circ\else\textdegree\fi{} have been observed. The mean free path against scattering, and the corresponding scattering cross section per nucleon have been estimated in each case. The total scattering cross section per nucleon is of the order of magnitude of several millibarns. This figure may be compared with the total theoretical meson-nucleon scattering cross section calculated from pseudoscalar or scalar theory for meson energy equal to several times its rest energy. Perhaps, it is several times smaller than the total experimental nucleon-nucleon scattering cross section for, say, 300-Mev proton energy. Our experimental cross section probably represents the combined effect of meson-nucleon and nucleon-nucleon scattering.