Large volume imaging arrays for gamma-ray spectroscopy

We report for the first time on the characteristics of large volume (4 cm x 4 cm x 0.5 cm) cadmium zinc telluride gamma-ray imaging arrays produced by IMARAD Imaging Systems. These arrays are shown to posses high uniformity o f response to gamma-photons in the energy range of about 50 to over 600 keV . High resolution photopeaks have been obtained without any pulse processin g or compensation techniques. Excellent peak-to-valley ratios, good efficie ncies, and acceptable leakage currents have been measured. In addition meas urements of the internal electric field indicate that the field is uniform and does not appear to be confined to only one region of the detector volum e. Low temperature photoluminescence spectroscopy shows that the dominant p eaks are different than those typically observed in high quality HPB materi al of the same composition obtained from other vendors. We believe that thi s material and the arrays that may be produced from it represent a signific ant step forward in the technology of room temperature semiconductor gamma and x-ray spectrometers.