Saturation characteristics of the ionization chamber at a low dose rate

We have designed and fabricated an ionization chamber as the detector for the radiation area monitor. The saturation curves of the ionization chamber were measured at low dose rates. The previous quantitative method to determine the fractions of the initial and the general recombination was revised, and the initial recombination component in the ion recombination process was obtained with a new formula. The validity of the two voltage method, in which the ions are assumed to recombine through a general recombination, at a low dose rate was studied. Although the initial recombination becomes predominant as the dose rate gets lower, the two voltage method was still valid within error bar in our measurement.