Efficient Large-area X-ray Detectors

High energy (30-90 keV) x-rays are critical for exploring failure modes of lightweight structural materials and for determining the details on atomic bonding in crystalline materials being developed for catalytic and energy storage applications. Detectors for the x-ray diffraction patterns from these high-energy x-rays must have a combination of good efficiency and good spatial resolution. Current technology, based on scintillators or silicon detectors is limited in spatial resolution and efficiency. We have developed processes for growing polycrystalline mercuric iodide films directly onto readout chips, providing a direct-converter semiconductor x-ray detector with good efficiency and excellent spatial resolution, and with reasonable cost for large-area devices. This Small Business Innovation Research Phase II project will produce a commercial imaging system with the characteristics needed for high-energy x-ray diffraction analysis. In Phase I we refined the existing coating technology to improve the spatial resolution, uniformity, and signal to noise ratio and evaluated the coating on both our own integrating-signal small-area chip (2 cm2) and the photon-counting Timepix chip (2 cm2). In Phase II we will fabricate and coat a large integrating chip (13 cm2), design a readout system to meet the frame readout speed requirements, and then test the system at the Stanford Synchrotron Radiation Lightsource (SSRL) in realistic x-ray diffraction studies. We will develop and market this large-area detector system to synchrotron facilities and to medical imaging equipment manufacturers. Commercial Applications and Other Benefits The system we will develop in this Phase II SBIR will meet the specific requirements expressed in the topic description and will be a commercial product available for use at all beam line facilities worldwide that produce x-ray diffraction studies. The device will also compete with current commercially available low-energy x-ray detectors, for example, those used in protein crystallography studies. The detector we develop will also have potential for use in medical imaging applications that require high resolution and real-time imaging capabilities, such as planar x-ray imaging of the beating heart and mammography.