Unipolar charge sensing with coplanar electrodes -- Application to semiconductor detectors

A novel method to perform preferential sensing of single-polarity charge carriers in ionization detectors is presented. It achieves the same function as Frisch grids commonly employed in gas ion chambers but uses a coplanar electrode configuration that allows it to be applied to semiconductor detectors. Through the use of this method, good energy resolution can be obtained from room-temperature compound semiconductor detectors despite their poor hole-collection characteristics. Experiment using a CdZnTe detector demonstrates the effectiveness of this technique. Schemes to correct for electron trapping and to obtain position information are also described