3.2.4.1 Ionization chambers

Ionization chambers (IC) are designed to operate at saturation. The average current output is measured and is proportional to the amount of radiation to which the chamber has been exposed. The design of ionization chambers and the choice of filling gas depend on the particular application of the instrument. Ionization chambers use a relatively low electric field of about 100 V/cm to extract all ions and electrons before they recombine. This gives a steady current proportional to the dose rate the gas is exposed to.

Ion chambers are widely used as hand held radiation survey meters to check radiation dose levels. As the discharge time is very short, IC can measure fluxes up to 10¹¹ photons/s/cm³, and are often used to measure x-ray beam fluxes in absorption experiments.