Thin-walled parallel plate ionization chamber for use with photon and electron beam dosimetry

The design and construction of a thin-walled parallel plate ionization chamber is described. The chamber makes use of a sputtered collecting electrode. The characteristics of this chamber include low leakage (less than 10(-13) A), no stem effect, and reproducibility within 1%. No polarization effects have been seen for electron beams over an energy range 7-25 MeV while for cobalt 60-25 MV photon beams, it is only 10%-15%.