High pressure tissue-equivalent ionization chamber for radiation protection applications

This short report describes a thimble-type tissue-equivalent (TE) ionization chamber with a sensitive volume of about 1 cm3 which can be operated at gas pressures of up to 100 bar. For approximately the same pressures, the saturation characteristics for 137Cs gamma rays are not significantly different. The results of measurements at various values of the collecting potential are given for TE gas at a pressure of about 62 bar for different types of radiation, and these indicate that the influence of initial recombination is dependent on the type of radiation employed and increases with increasing quality. At a fixed collecting potential of 600V, the ionization chamber reading relative to the reading at 1 bar as a function of gas pressure is presented for various types of radiation, which indicates that it is possible to assess radiation quality from the pressure dependence of the reading. (Auth./C.F.)