How does a Geiger counter detect radiation?

A Geiger counter detects radiation by measuring the ionizing effect of radiation on a gas-filled tube.

A Geiger counter is a device used to detect and measure ionizing radiation. It consists of a gas-filled tube, typically made of metal, with a thin wire running down the centre. When ionizing radiation enters the tube, it ionizes the gas molecules, creating a current of charged particles that flows towards the wire. This current is then amplified and counted by the Geiger counter.

The gas-filled tube in a Geiger counter is typically filled with a low-pressure inert gas, such as helium or neon, and a small amount of a halogen gas, such as iodine or bromine. The halogen gas helps to increase the sensitivity of the tube to ionizing radiation.

When ionizing radiation enters the tube, it ionizes the gas molecules, creating a cascade of ionization events that produces a large number of charged particles. These charged particles then create an electrical pulse that is detected by the Geiger counter. The size of the pulse is proportional to the energy of the ionizing radiation that entered the tube.

Geiger counters are commonly used in a variety of applications, including radiation protection, nuclear medicine, and environmental monitoring. They are simple to use and provide a quick and easy way to detect the presence of ionizing radiation. However, they are not suitable for measuring the energy or direction of the radiation, and are typically used in conjunction with other instruments for more detailed measurements.