A three dimensional beam profile monitor based on residual and trace gas ionization

A three dimensional beam profile monitor based on tracking the ionization of the residual gas molecules in the evacuated beam pipe is described. Tracking in position and time of the ions and electrons produced in the ionization enables simultaneous position sampling in three dimensions. Special features which make it possible to sample very low beam currents were employed. The characteristics of this detector make it particularly suitable for sampling beams produced at radioactive beam facilities, provided an auxiliary gas feed can be utilized.