LXI. The penetrating component of cosmic radiation in the upper atmosphere

Abstract

Summary The vertical intensity of the hard component of cosmic radiation has been measured in geomagnetic latitude 56°, to a minimum atmospheric depth of 4 g/cm2. The intensity, determined with a precision of 2·5%, shows no maximum. This agrees closely with the results of Pomerantz. The primary particle flux at this latitude, capable of penetrating 90 g/cm2 of lead is found to be 0 ·164±0·003 particles cm−2 sec−2 ster−1. The flux of μ-mesons in the upper atmosphere has been derived, and shows a maximum of 0.039 particles cm−2 sec−1 ster−1 at a depth of 150 g/cm2. Penetrating showers produced in lead have also been measured to a minimum atmospheric depth of 7 g/cm2, the primaries being found to have an absorption length of 120 g/cm2 of air.