"An electrically isolated or electronically connected gas-filled radiation detection chamber operated in the ""ionization chamber"" voltage region. It is used with portable survey meters, stationary radiation monitors or analytical counting instruments. The incident radiation sets up a characteristic ""saturated current"" within the chamber. A number of probes with different size chambers and chamber wall thicknesses are needed to cover the possible range of radiation energies and doses. It is very stable over time and may be used for accurate dosimetry measurements, e.g., source calibrations and inter-comparisons. For accurate measurements, temperature and pressure corrections are needed."