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%.