New Virtual Frisch-Grid CdZnTe Detector Design With Sub-Millimeter Spatial Resolution

We evaluated the performance of a position-sensitive virtual Frisch-grid (VFG) CdZnTe detector,
$6~\hbox{mm} \times 6~\hbox{mm} \times 15~\hbox{mm}$
, via sensing strips on its side surfaces. Once the signals were collected from the anode, and from four or eight strips attached to the detector’s sides, we assessed the anode’s energy spectra and derived histograms from the side electrodes to evaluate the feasibility of achieving sub-millimeter spatial resolution in the X-Y plane. Using a highly collimated 30-keV X-ray beam at the National Synchrotron Light Source, and applying corrections to the raw data, we determined the photon-interaction points by conventional Anger logic and via a more sophisticated statistics-based positioning (SBP) algorithm. With the VFG detector’s current configuration, we achieved a resolution below 1 mm, even for low-energy X-rays.