Performance of 3-D position sensitive CdZnTe detectors for gamma-ray energies above 1 MeV

• Published in: 2009 IEEE Nuclear Science Symposium Conference Record (NSS/MIC) pp. 2012 - 2016
• Main Authors: Feng Zhang, Kaye, W.R., Zhong He
• Format: Conference Proceeding
• Language: English
• Published: IEEE 01-10-2009
• Subjects: Anodes; Application specific integrated circuits; Cathodes; Energy resolution; Event detection; Gamma ray detection; Gamma ray detectors; Helium; Image reconstruction; Position sensitive particle detectors
• ISBN: 9781424439614; 1424439612
• ISSN: 1082-3654; 2577-0829
• DOI: 10.1109/NSSMIC.2009.5402137

A 3-dimensional position-sensitive CdZnTe gamma-ray detector employs a pixellated anode (11 × 11 pixels) and a planar cathode on a 15 × 15 × 10 mm 3 or 20 × 20 × 15 mm 3 CdZnTe single crystal. The signals from the 121 pixels and the cathode read out by Application Specific Integrated Circuits (ASIC) are used to reconstruct the energy depositions and 3-D coordinates of multiple gamma-ray interactions inside the detector. The best energy resolution of a given detector can be achieved by using the 3-D position sensitivity to correct the signal variations due to charge trapping and material non-uniformity. We have demonstrated excellent energy resolution of better than 1% FWHM at 662 keV in a dozen CdZnTe detectors ranging from 2.25 cm 3 to 6 cm 3 in size. In this study, the energy resolution of four 6 cm 3 3-D position sensitive CdZnTe detectors at gamma-ray energies higher than 1 MeV (up to 2.6 MeV of 228 Th) are reported. Various challenges in events calibration/reconstruction at high gamma-ray energies and possible solutions are discussed.