Variation of electric shielding on virtual Frisch-grid detectors

Array of virtual Frisch-grid CZT detectors with common cathode readout and pulse-height correction

“…The special resolution provided by the array (determined by the cross-sectional area of the bars) is suitable for using such arrays as detection planes in coded-aperture telescopes. As we demonstrated previously [6][7][8], an energy resolution between 0.8-and 1.5% -FWHM at 662 keV can be achieved with regular spectroscopic-grade CZT material; this is about twice the resolution obtained for 3D devices, 0.6%, made from the pre-selected crystals. This resolution is adequate for resolving most gamma-ray spectra.…”

“…CZT detectors operate as single-type carrier (electrons), meaning that the devices' geometrical parameters and contacts configurations should be chosen so to minimize the contribution of uncollected holes, whose effect on output signals depends on the location of interaction points. In this work, we investigated the performance of 6x6x15 mm 3 virtual Frisch-grid detectors [2][3][4][5][6][7][8] assembled in 4x4 detector arrays with a common cathode-readout for correcting pulse-height and rejecting incomplete charge-collection events. This type of detector provides excellent energy resolution, <1.5% FWHM at 662 keV, and large effective areas.…”

“…Implementing a cathode-readout scheme assures this by allowing us firstly to correct for electron trapping, and secondly, to reject events interacting near the anode and contributing to the background. Previously, we demonstrated that, in 15-mm long detectors, a wide area near the cathode can be left uncovered by the shield without lowering the effectiveness of shielding the anode [8]. Furthermore, assembling the arrays in which the cathodes of several detectors, i.e., the 4x4 modules, are connected together enhances the shielding effect.…”

Further process of polarization within a pixellated CdZnTe detector under intense x-ray irradiation

“…Recent improvements in growth techniques have improved the CdZnTe material quality and charge transport properties, resulting in detectors with improved energy resolution [7][8][9]. This has opened a wide field of potential applications of CdZnTe detectors for national security, medical, space, basic science and environmental mitigation and safety.…”

Hybrid contacts for CZT virtual Frisch-grid detectors

“…The geometry of its electrodes [3] includes the features of two designs others previously proposed for bar-shaped CZT detectors: The CAPture device [4,5], and the Frisch-ring (or capacitive Frisch-grid) detector [6,7]. The shielding electrode, disconnected from the cathode by its optimized length of 4-5 mm, extends from the anode toward the cathode [8]. As in the Frisch-ring device, a thin layer of insulating material lies between the metal shield and CZT's surface.…”