Abstract
The accuracy of Boag's formula and two-voltage technique for determining the ion collection efficiency of an ionization chamber exposed to high-intensity pulsed radiation is examined. Results with these methods were compared to the experimental ion collection efficiencies estimated with the saturation charge by graphical extrapolation. When the influence of the space charge can be ignored, results with the two-voltage technique show much better agreement with the experimental values. Results with Boag's formula give a discrepancy between the experimental values at high charge density because an unreliable value (nominal value) is used for the effective electrode spacing of the ionization chamber. Therefore, we investigated the effect of the effective electrode spacing for real ionization chamber estimated with the two-voltage technique. We found that the results with Boag's formula using the estimated effective electrode spacing agree much better with the experimental values even at high charge density.
