Wall effect in ionization chambers for tritium measurements

Wall effect in ionization chambers for tritium measurements has been studied in this paper. Theoretical analysis with a model based on the continuous slowing-down approximation (CSDA) is employed to obtain the relationship between wall effect and pressure in the chamber, which follows cubic polynomial. Two ionization chambers of different volumes are used in the experiment. Results show that the counting losses due to wall effect are as much as 17.62% for ionization chamber of volume 1.1 L at pressure 71 mmHg, and 28.54% for 0.3 L. Both linear polynomial with logarithm scale and cubic polynomial are used to fit the results, which agrees very well with the theoretical analysis. Monte Carlo simulations are also introduced to calculate the loss part of electrons due to wall effect, which show accordance with the experimental results.