Specific Ionization of Cosmic Ray Particles

Abstract

MEASUREMENTS of the specific ionization of cosmic ray electrons with energies between 0.1 × 106 ev. and 30 × 106 ev. have been made by Corson and Brode1 by counting droplets on photographs taken with a counter-controlled cloud chamber using a delayed expansion. They established the existence of a minimum ionization at about 1.5 × 106 ev. and a logarithmic increase in ionization with energy beyond this minimum. Using essentially the same method, I have measured the specific ionization of cosmic ray particles over the energy range 2 × 106–6 × 109ev.