Penetrating Cosmic Ray Showers

IT is now recognized that the majority of cosmic ray showers at sea-level consist of electron cascades (see, for example, Jánossy1 and Lovell2). The present investigation gives evidence for the existence of a very small number of penetrating showers remaining after the cascades have been removed by suitable absorbers. The frequency of these penetrating showers, however, amounts only to a few per cent of all showers at sea-level. They therefore could not be detected in the experiments referred to above, or in the similar experiments of Schmeiser and Bothe3.