Ionization chambers

The equipment, working principles, performance and disturbing effects of re-entrant ( or 4 pi) pressurized ionization-chamber measuring systems for activity determinations of photon-emitting radionuclide sources are described. Important features of these systems are the measuring geometry-generally reproducible and repeatable, ' stable' measurement conditions and instrument response, in particular linearity with varying activity. Properties of the current-measuring electronics are also considered. Basic equations for instrument calibrations and related uncertainties are given. A few applications, particularly half-life measurements, are represented. Finally, the bibliography of publications during the past ten years is reviewed.