Experimental Demonstration of Coded Aperture Imaging using Thick 3D-Position-Sensitive CdZnTe Detectors

3D-position-sensitive CdZnTe semiconductor detectors have demonstrated 4 pi Compton imaging capability and excellent energy resolution at room-temperature operation. However, Compton gamma-ray imaging is not feasible at low energies due to the small Compton-scatter cross-section. This work extends the current imaging capabilities to lower energies by utilizing coded aperture masks. Multiple coded aperture masks are applied to a single detector system of four 20mmx20mmx15mm CdZnTe detectors. Near-4 pi coded aperture imaging has been demonstrated through Monte Carlo simulation. The correct source direction is consistently identified using measured data with one mask above the cathode side and another mask above the non-cathode side of the detector. Challenges related to electric field distortion due to space charge in the detector are discussed. The focus of this research is to image near-4 pi field of view using coded apertures, ultimately, combining both Compton and coded aperture imaging techniques to expand the range of gamma-ray imaging.