Monte Carlo simulation of the effective point of measurement of the Markus chamber for electrons, the upright PinPoint chamber for photons, and other chambers

Monte Carlo simulation is shown to provide an ideal tool for the study of effective point of measurement (P/sub eff/) shifts in some electron chambers such as the Markus chamber at all energies or chambers of 2 mm plate separation at very low electron energies. Furthermore it enables the definition of P/sub eff/ for the PinPoint chamber in the upright orientation in photon and electron beams.