Measurement of material uniformity using 3-D position sensitive CdZnTe gamma-ray spectrometers

We present results from two 1 cm(3) CdZnTe gamma-ray spectrometers with full 3-D position sensitivity. To our knowledge, these are the first reported semiconductor spectrometers that provide independent spectral data for each of over 2000 volume elements. Energy resolutions of 1.5-1.6% FWHM and position resolutions of 0.7 x 0.7 x 0.5 mm were obtained at 662 keV gamma-ray energy from the central region of both detectors for single-pixel events. With the 3-D position sensing capability variations in spectral response over the detector volume were recorded using a Cs-137 source. These measurements allow a study of full-energy peak efficiency, mean ionization energy and electron trapping as a function of 3-D position. The effects of material non-uniformity on detector spectroscopic performance are discussed. (C) 2000 Elsevier Science B.V. All rights reserved.