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Proceedings Paper

Achieving subpixel resolution with time-correlated transient signals in pixelated CdZnTe gamma-ray sensors using a focused laser beam (Conference Presentation)

Paper Abstract

High-resolution position-sensitive detectors have been proposed to correct response non-uniformities in Cadmium Zinc Telluride (CZT) crystals by virtually subdividing the detectors area into small voxels and equalizing responses from each voxel. 3D pixelated detectors coupled with multichannel readout electronics are the most advanced type of CZT devices offering many options in signal processing and enhancing detector performance. One recent innovation proposed for pixelated detectors is to use the induced (transient) signals from neighboring pixels to achieve high sub-pixel position resolution while keeping large pixel sizes. The main hurdle in achieving this goal is the relatively low signal induced on the neighboring pixels because of the electrostatic shielding effect caused by the collecting pixel. In addition, to achieve high position sensitivity one should rely on time-correlated transient signals, which means that digitized output signals must be used. We present the results of our studies to measure the amplitude of the pixel signals so that these can be used to measure positions of the interaction points. This is done with the processing of digitized correlated time signals measured from several adjacent pixels taking into account rise-time and charge-sharing effects. In these measurements we used a focused pulsed laser to generate a 10-micron beam at one milliwatt (650-nm wavelength) over the detector surface while the collecting pixel was moved in cardinal directions. The results include measurements that present the benefits of combining conventional pixel geometry with digital pulse processing for the best approach in achieving sub-pixel position resolution with the pixel dimensions of approximately 2 mm. We also present the sub-pixel resolution measurements at comparable energies from various gamma emitting isotopes.

Paper Details

Date Published: 8 June 2017
PDF: 1 pages
Proc. SPIE 10229, Photon Counting Applications 2017, 1022907 (8 June 2017); doi: 10.1117/12.2264615
Show Author Affiliations
Luis A. Ocampo Giraldo, The Pennsylvania State Univ. (United States)
Aleksey E. Bolotnikov, Brookhaven National Lab. (United States)
Giuseppe S. Camarda, Brookhaven National Lab. (United States)
Yonggang Cui, Brookhaven National Lab. (United States)
Gianluigi De Geronimo, Brookhaven National Lab. (United States)
Rubi Gul, Brookhaven National Lab. (United States)
Jack Fried, Brookhaven National Lab. (United States)
Anwar Hossain, Brookhaven National Lab. (United States)
Kenan Unlu, The Pennsylvania State Univ. (United States)
Emerson Vernon, Brookhaven National Lab. (United States)
Ge Yang, Brookhaven National Lab. (United States)
Ralph B. James, Savannah River National Lab. (United States)

Published in SPIE Proceedings Vol. 10229:
Photon Counting Applications 2017
Ivan Prochazka; Roman Sobolewski; Ralph B. James, Editor(s)

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