Performance of 8×8×32 and 10×10×32 mm3 CdZnTe position-sensitive virtual Frisch-grid detectors for high-energy gamma ray cameras

A. E. Bolotnikov, J. MacKenzie, E. Chen, F. J. Kumar, S. Taherion, G. Carini, G. De Geronimo, J. Fried, Kihyun Kim, L. Ocampo Girado, E. Vernon, R. B. James

Research output: Contribution to journalArticle

Abstract

CdZnTe (CZT) crystals with thicknesses up to 20 mm and diameters up to 75 mm have become available from Redlen Technologies, Inc. for making large-volume gamma-ray detectors. The modified growth and optimized annealing conditions allowed Redlen to minimize the dark current and improve the uniformity of CZT crystals. Two detector designs, pixelated (H3D) and position-sensitive virtual Frisch-grid (VFG), have greatly benefitted from the availability of such big crystals. Encouraging results from testing of 40×40×15 mm3 pixelated detectors were recently reported by the University of Michigan. Here, we evaluated the spectroscopic properties of 8×8×32 and 10×10×32 mm3 crystals configured as position-sensitive VFG detectors. Both digitized waveforms and an analog ASIC were used to read and process the signals from the detectors and test their spectral- and spatial-resolution. The VFG design provides the flexibility to scale-up the dimensions of the detectors for the desired efficiency, while the position information allows for correcting the detectors’ response non-uniformity caused by crystal defects and devices geometry, thereby reducing the instrument cost and making them more feasible for emerging applications in gamma-ray astronomy, nonproliferation, portal screening and nuclear safeguards, where large detector arrays are often required.

Keywords

  • CdZnTe
  • CdZnTe detectors
  • Crystal defects
  • Gamma-ray imaging
  • Position-sensitive virtual frisch-grid detectors

ASJC Scopus subject areas

  • Nuclear and High Energy Physics
  • Instrumentation

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