There are three major methods of detecting radiation: scintillation counters, film badges and the most frequently used device for detecting ionizing radiation and measuring the level of radioactivity the Scaler/Timer in combination with the Geiger-Muller tube.

Scaler/Timer with the Geiger-Muller tube

 

      The radiation emitted by radioisotopes is an ionizing radiation. The ionizing radiation, as you are aware, results in the removal of electrons from atoms resulting in the production of ions. The Geiger-Muller tube is the most efficient in the detection of beta particles which will ionize and produce these ions. In its simplest form, the G-M tube consists of a thin wire (anode) suspended in the center of a metallic cylinder(cathode). The cylinder is filled with a gas at low pressures such that as beta particles pass through the window they will ionize the gas producing ions that are attracted to the electrodes. The motion of the ions to the electrode produces an electronic current which is subsequently detected and recorded by the Scaler/Timer.