Evidencing Cosmic Rays with a Geiger

A large part of the events detected by a Geiger counter in standard conditions, i.e. when no specific radioactive material is positioned close to it, is due to the secondary cosmic radiation. Particles from the cosmic radiations, especially muons, are characterized by a large penetrating power. This is demonstrated in this activity by measuring the count rate of a Geiger counter with metal layers of increasing thickness, which act as a shield for low energy radiations, mainly of terrestrial origin, but are not enough to stop the high-energy components detected in the counter.