Extensive Air Showers at High Altitudes

Abstract

The latitude dependence, density properties, and lateral extension of extensive cosmic-ray air showers have been studied at 9200 m elevation, with coincidence counters in a B-29 airplane. On a flight between 0\ifmmode^\circ\else\textdegree\fi{} and 63\ifmmode^\circ\else\textdegree\fi{}N geomagnetic latitude, no significant variation of shower frequency with latitude has been detected.Relations between the counting rates of coincidence counter sets of different orders from threefold to ninefold are in agreement with a power law density spectrum for the showers, with constant negative exponent. The measured value of this exponent is 1.73\ifmmode\pm\else\textpm\fi{}0.04 at 9200 m, 1.82\ifmmode\pm\else\textpm\fi{}0.07 at 11,000-12,000 m, and 1.53\ifmmode\pm\else\textpm\fi{}0.07 at 720 m. The counting rate of a threefold coincidence counter set was found to decrease 33 percent as the total spread of the counters was increased from 2.8 m to 13 m at 9200 m altitude. The corresponding decrease at 720 m is 21 percent. The altitude dependence of the extensive showers was measured up to 12,300 m, and a definite maximum shower rate has been found near an altitude of 8000 m.