Analysis of ion recombination in ionization chambers for tritium measurements

• A theoretical method was developed to evaluate ion recombination quantitatively.
• The established theoretical method is suitable for both two and three dimensions.
• Recombination coefficient in dry air was determined to be around 6.9 × 10−6 cm3/ion s.
• This method is also suitable for other kinds of gas and for chambers of different sizes.

Ion recombination in ionization chambers for tritium measurements has been studied theoretically and experimentally. A two-dimensional model for ionization chamber of cylindrical form was introduced to derive theoretical formulas for evaluating ion recombination loss quantitatively, and it can be extended to three dimensions easily. Experiments were carried out with an gold plated ionization chamber of 1.0 L at tritium concentration 1.10 × 1011 Bq/m3 and 1.98 × 1010 Bq/m3. With the established theory, recombination coefficient was determined to be around 6.9 × 10−6 cm3/ion s in dry air, which agreed with value reported recently in the literature. In addition, ion densities in ionization chamber have been investigated, which shows good accordance with experiments. Furthermore, this proposed method for analyzing recombination coefficient is also suitable for other kinds of working gas besides dry air and for ionization chambers of different sizes.