Position sensing in a cylindrical ionization detector through use of a segmented cathode

Position sensing in radiation detectors is essential for imaging applications and improved energy resolution. We propose an electrode configuration for cylindrical ionization chambers that accurately senses the radial and azimuthal coordinates of interaction vertices. The cathode of the proposed design is segmented into six longitudinal strip electrodes. Signals read out from each electrode are used in a computational scheme that accurately predicts the location of interacting events inside the detector, as indicated by Monte Carlo simulations. These show that the spatial resolution offered by a 24 mm diameter detector is 1 mm at 140 keV and 0.5 mm at 511 keV (assuming a root-mean-square amplifier noise of 50 electrons). At the same noise and energy levels, full-width-at-half-maximum energy resolution is 7.1% and 2.3%, respectively. These values indicate significant improvement over conventional detectors.