Evaluation of counting loss and its correction for small pulses in internal counting with proportional counters

In the absolute radioactivity determination of gaseous samples using the internal gas counting method with proportional counters, evaluation of counting losses of pulses whose pulse heights are lower than the discrimination level is very important to obtain high accuracy. Counting losses due to wall effect and to very low energy of a β-ray were evaluated by experiment and EGS4 Monte Carlo calculation. The calculated results agreed well with experimental results when parameters in the EGS4 code were properly chosen; which shows the calculation code is able to be applied to other radioactive nuclides and other measurement conditions for the evaluation of counting losses.