Long term reliability is critical for a detector module to be used in applications that can not afford failure and require high accuracy such as medical imaging and homeland security. In this study, we report the reliability of pixellated Cadmium Zinc Telluride (CZT) detector modules fabricated from crystals grown by the Traveling Heater Method (THM). The reliability of the module which consists of the pixellated detector assembled to a PCB carrier board via conductive epoxy was studied with both a Quantitative Accelerated Life Test (QALT) as well as the Highly Accelerated Stress Test (HAST) which is a common form of a Qualitative Accelerated Life test. The robustness of the THM pixellated CZT detector modules is demonstrated via the pre-and post-accelerated life test comparison of the leakage current and the spectral performance of the assembled module. A shear test was also used to ensure the adhesion strength of the epoxy bonded method. To our knowledge, this type of study on pixellated CZT detector module has been very rare if not the first of its kind.
Coded mask imaging can produce excellent images in the hard X-ray range from -10 to 200 keV, and up to several MeV in the gamma-ray range. Sub-degree resolution is obtained for hard X-rays and a few-degree resolution for gamma-rays. However, these capabilities are realized with large instruments, several meters in length, and limited fields of view, tens of degrees, which are not suitable for large-area surveillance to assess radiological threats. We have developed coded mask imaging techniques to address this deficiency. They operate into the MeV range and provide high sensitivity over a wide FOV, 140 degrees, with a single instrument. This is possible by designing for limited angular resolution, -20 degrees, in order to reduce the otherwise negative consequence of vignetting by the mask. With this resolution, few-degree localizations are obtained with detections of -10 sigma significance, which usually provides adequate positioning to associate a radiation source with a specific object for follow-up investigation. We report on the design, modeling, and tests of a hand-held CZT-based coded mask imager that uses these techniques to image a 140 degree FOV with a nearly constant resolution of 20 degrees. The 7.5 mm thick coded mask provides good modulation and, therefore, good sensitivity up to 1 MeV and beyond, and the sensitivity is nearly uniform across the FOV due to an optimized coded mask/detector array design. The imager employs CZT pixel detectors that provide -1 % energy resolution at 662 keV
The drive towards miniaturization has created increasing challenges to the overall failure analysis and quality inspection of electronic devices. This trend has equally challenged the image quality of x-ray inspection systems – engineers need to see more details in each inspection. Image quality is paramount to the ability of making actionable decisions on the information acquired from an x-ray machine. Previous generations of x-ray technologies have focused on hardware improvements – better x-ray sources and better x-ray sensors. Although further improvements can still be achieved in hardware, our focus will be on the latest wave of technology breakthroughs and innovation in radiography systems: algorithms.
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