Determination of Ion Recombination Correction Factor in a Spherical Ionization Chamber for ⁶⁰Co Gamma-Ray

In the determination of air kerma using an ionization chamber one of the important correction is the ion recombination correction. This phenomenon occurs when the + and - ions formed along the charged particle tracks meet and recombine. There are two processes in the ion recombination. One is the initial recombination process that occurs when ions from the same charged particle track meet to recombine and the other is the volume recombination process that occurs when ions from different tracks encounter each other on their way to the collecting electrode. The purpose of the present paper is to investigate the problem of ion recombination in a spherical ionization chamber and obtain parameters governing the initial and volume recombination to determine the ion recombination correction factor for ⁶⁰Co gamma-rays. The spherical ionization chamber used in this study was a 1 cm³ graphite wall chamber (FWT-182). The problem of ion recombination in a spherical ionization chamber for ⁶⁰Co gamma-ray was investigated experimentally. The initial and volume recombination parameters A and B have been obtained from the measurement of the ratio of I _V/I_V/n as a function of I _V at two given applied voltages V and V/n, where n is a positive number, as a function of I_V . From these parameters, the ion recombination correction factor was determined.