Design and application of an ultra low current digitizer with large dynamic range

Ultra low current measurement technique is very important for the signal readout of some radiation detectors, especially the ionization chambers which are widely used to monitor the γ-ray background inside and around the radiation field. We have designed an ultra low current digitizer with large dynamic range, which has been built into a γ-ray monitor together with an ionization chamber. Test results show the γ-ray monitor has low temperature dependence and good stability and can work well in outdoor environment.