3-D position sensitive CdZnTe gamma-ray spectrometers

Two 3-D position-sensitive room temperature semiconductor γ-ray spectrometers have been built using 1 cm3 cubic CdZnTe crystals. The lateral coordinates of γ-ray interaction are obtained from the location of the 11(x)×11(y) pixellated anodes and the depth (z) is obtained from the ratio of the signals coming from the cathode and the anode. Energy spectra from 662 keV incident γ-rays have been collected from each of the 11 (x)×11 (y)×20 (z) voxels in both of the CdZnTe devices. After corrections for electron trapping, the difference of weighting potentials in 3-D, and for the gain variation of the readout circuitry, energy resolutions of 1.70% (11.3 keV) FWHM and 1.84% (12.2 keV) FWHM were obtained at 662 keV γ-ray energy on the first and second detectors, respectively, from the whole bulk for single-pixel events. Possible improvements in the detector performance are discussed.