Composition of Cosmic Rays

The new information regarding the absorption of high energy photons and electrons, presented at the recent International Congress on Nuclear Physics, suggests an improved interpretation of certain cosmic ray phenomena. Three distinct components of cosmic rays have been recognised. Eckart's analysis 1 of the depth v. ionisation data shows clearly the presence of two components in the cosmic rays which reach the earth's surface. These components have mean absorption coefficients of about 0·6 and 0·06 respectively per metre of water. Gross 2 and Compton and Stephenson 3 find that the high altitude data from stratosphere balloons also indicate the presence of two components, the more penetrating of which is probably identical with Eckart's less penetrating component. Let us call these components A, B and C in the order of their penetrating power.