Ionizing radiation that is associated with radioactivity cannot be directly detected by our senses. Ionization is the process whereby the radiation has sufficient energy to strip electrons away from atoms. The ionization results in the formation of free electrons and an ionized atom that has lost some of its orbital electrons. Examples of ionizing radiation include particles such as alpha and beta particles, and photon radiation such as x-rays and gamma rays. Neutrons and protons can also cause ionizations. Since radiation can be harmful to our health, we need detectors that are capable of sensing the presence and intensity of radiation and convert it into an electrical signal to provide suitable alarm. Geiger-Müller tubes are gas-filled radiation detectors that are useful, cheap and robust. A GM tube basically detects the presence and intensity of radiation (particle frequency, rather than energy). Geiger counters are used to detect radiation (usually gamma and beta radiation, but some models can also detect alpha radiation).Geiger-mueller counters respond to the commonly encountered types of radiation, namely, alpha and beta particles as well as gamma and x-radiation. In general, GM counters cannot determine the type, energy, or vectors of the detected radiation. Generally they are used for detecting and measuring radioactivity that consists of low level beta particles and gamma-ray radiation. It has high sensitivity, versatility with various types of radiation, wide variety of shapes and windows, large output signal and reasonable cost.
