New ’’wall-less’’ ionization chamber for air dose measurement

A simple mesh wall ionization chamber (representing a ’’wall-less’’ ionization chamber) is described for air dose measurement. The effects of insulators and air circulation in the vicinity of the chamber were studied. An outer shield mesh placed around the collecting chamber eliminates the adverse effects of air circulation and electrostatic disturbances around the detector. The detector can be used effectively to measure that component of dose due to low energy electrons or x rays which are normally stopped by the walls of conventional dose measuring instruments. The mesh ion chamber is particularly useful in measuring dose distribution in and around a radiation field. This chamber approximates a free air ion chamber that can be used at low, as well as high, energies once electron equilibrium is achieved. The chamber was tested using 137Cs gamma radiations and gives good agreement with a model 570 Victoreen R meter.