The Transition Effect for Large Bursts of Cosmic-Ray Ionization and the Number of Primary Electrons of Very High Energy

Bursts of cosmic-ray ionization were observed in the open air and under heavy roofs, with and without a one-cm lead plate over the ionization chamber. The increase in the number of bursts in the presence of the lead under heavy roofs is interpreted as an increase in the number of rays in the showers from the roof, while in the open air the bursts from the lead probably originate to a large extent from the action of electrons of high energy which are not members of cascade showers starting at the top of the atmosphere. If the bursts from the atmosphere with no lead present are to be accounted for by the assumption that they are parts of extensive cascade showers, it is possible to derive the number and energy distribution of the primary cosmic-ray electrons of energies of the order of 2×${10}^{15}$ electron volts.