Схема без компонент за Гейгер - ГЕЙГЕРОВ СЧИТАТЕЛ
The matter is made of atoms. Each atom has a nucleus composed of protons and neutrons. The core is surrounded by electrons orbiting like satellites. Radioactive materials spontaneously emit radiation Gamma or X and / or beta particles or sometimes alpha.
Beta particles are electrons. Because of their charge, they react strongly with matter. They travel a few centimeters to several meters in the air. Aluminum foil can stop them.