The Absorption Curve of the Cosmic Radiation in the Stratosphere

Abstract

The absorption in lead of cosmic-ray particles has been measured at an altitude of 5.7 cm Hg with hitherto unattained accuracy. The absorption at this altitude is compared with the absorption at sea level. It is found that the soft component shows an increase by about a factor of 90. The hard component shows an absorption length of about 220 grams per ${\mathrm{cm}}^{2}$ of Pb, very different from the sea level absorption of $\ensuremath{\mu}$-mesons. It is concluded that most of the penetrating particles at 5.7 cm Hg are nucleons.