Investigation of a CPG-array CdZnTe γ-ray imaging detector with single collecting electrodes readout

The single-electrode readout method has been applied to a coplanar grid (CPG) array CdZnTe detector in order to halve the number of preamplifiers previously needed and to facilitate imaging applications of CPG detectors. A method of predetermining the width of the optimum collecting electrodes has also been proposed, using the calculated optimum relative gain factor G. Meanwhile, a detailed process for calculating the charge induction efficiency (CIE) is presented. To simplify the calculation process, the computational formula of the CIE was deduced through the integration of the weighting potential. For performance evaluation, a 2 x 2 CPG-array CdZnTe detector was elaborately designed and tested with Cs-137 at 662 keV. Experimental results showed the capability of using the CPG-array CdZnTe detector with single collecting electrode readout for gamma-ray imaging applications, with the same complexity of associated readout electronics as that of the pixelated CdZnTe detectors.