Geiger

A Geiger counter is an electronic instrument used for detecting and measuring ionizing radiation, particularly alpha particles, beta particles, and gamma rays, through the ionization effect produced in a Geiger-Müller tube. It is widely used in radiation dosimetry, radiological protection, and experimental physics due to its robust sensing element and relatively low cost, but has limitations in measuring high radiation rates and the energy of incident radiation. The device consists of a Geiger-Müller tube and processing electronics that display the result, and is known for its distinctive audible clicks representing the number of ionization events detected.learn more on wikipedia