The ionization chamber and proportional counter are two devices used to detect and quantify radiation. Both instruments measure the intensity of radiation and have immense application in research, medicine, and the nuclear industry. The ionization chamber is an electrical device that detects various types of ionizing radiation. It has a low bias voltage and can be used to measure only high-energy radiation.
Argon ions, also formed by the ionization process, move toward the walls of the opposite chamber. Those with low energy (E6 keV) exit the ionization chamber through a second window to enter the scintillation crystal. Operation as an ionization chamber involves the use of an applied voltage that is large enough to collect all ion pairs (positive ion and removed electron) produced in the gas by a radioactive source, but not large enough to cause any amplification of the gas. A proportional counter is a modified ionization chamber, one in which a higher voltage is printed, making the electric field near the axial cable strong enough to accelerate approaching electrons to such high energies that their collisions with gas molecules cause further ionization.
This device is capable of detecting the energy of the incident radiation and producing an output proportional to the intensity of the radiation. The Geiger-Müller counter has a high bias voltage and a quantum of radiation induces an electrical pulse of constant and high amplitude. It detects ionizing radiation, such as alpha particles, beta particles and gamma rays, using the ionization effect produced in a Geiger-Müller tube. In conclusion, both instruments can quantify the intensity of radiation and have immense application in research, medicine and the nuclear industry.
The ionization chamber has a low bias voltage and can be used to measure only high-energy radiation. The proportional counter has a higher bias voltage and is energy selective. The Geiger-Müller counter has a high bias voltage and a quantum of radiation induces an electrical pulse of constant and high amplitude.