Correction for recombination loss of ions in ionization chambers

The signal charge loss due to initial recombination and that due to volume recombination have been measured separately using parallel plate ionization chambers irradiated with cobalt-60 gamma rays, over a wide range of applied voltage and air humidity. It is shown that both initial and volume recombination depend on the electric field strength and also on humidity through ion clustering reaction with water molecules. In spite of the usual assumptions, a linear relation has not been observed between the inverses of the signal current and applied voltage for initial recombination, nor between the inverses of the signal current and square of the applied voltage for volume recombination. Methods and data which can be used for estimation of initial and volume recombination losses of ions in ionization chambers are proposed.