Progress on the design, fabrication, testing and assembly of two-layer Pixel Array Detectors (PADs) is described. The PADs are developed for challenging time-resolved X-ray imaging applications at synchrotron radiation X-ray sources.

The final technical report for DOE grant DE-SC0004079 is presented. The goal of the grant was to perform research, development and application of novel imaging x-ray detectors so as to effectively utilize the high intensity and brightness of the national synchrotron radiation facilities to enable previously unfeasible time-resolved x-ray research. The report summarizes the development of the resultant imaging x-ray detectors. Two types of detector platforms were developed: The first is a detector platform (called a Mixed-Mode Pixel Array Detector, or MM-PAD) that can image continuously at over a thousand images per second while maintaining high efficiency for wide dynamic range signals ranging from 1 to hundreds of millions of x-rays per pixel per image. Research on an even higher dynamic range variant is also described. The second detector platform (called the Keck Pixel Array Detector) is capable of acquiring a burst of x-ray images at a rate of millions of images per second.

This paper describes the development of a large-area hybrid pixel detector designed for time-resolved synchrotron x-ray scattering experiments where limited frames, with a high framing rate, is required. The final design parameters call for a 1024 x 1O24 pixel array device with 150-micron pixels that is 100% quantum efficient for x-rays with energy up to 20 keV, with a framing rate in the microsecond range. The device will consist of a fully depleted diode array bump bonded to a CMOS electronic storage capacitor array with eight frames per pixel. The two devices may be separated by a x-ray blocking layer that protects the radiation-sensitive electronics layer from damage. The signal is integrated in the electronics layer and stored in one of eight CMOS capacitors. After eight frames are taken, the data are then read out, using clocking electronics external to the detector, and stored in a RAM disk. Results will be presented on the development of a prototype 4 x 4 pixel electronics layer that is capable of storing at least 10,000 12-keV x-ray photons for a capacity of over 50 million electrons with a noise corresponding to 2 x-ray photons per pixel. The diode detective layer, electronics storage layer along with the radiation damage and blocking layers will be discussed.

We present description and documentation of the development and first applications of the Mixed-Mode Pixel Array Detector, a new type of imaging detector for synchrotron based x-ray science. Today there exists a great gulf between the intense x-ray fluxes that modern synchrotron light sources are capable of producing and the capabilities of imaging detectors to measure the resulting signal. This detector is intended to help bridge this gulf by offering readout times of less than 1 ms, a dynamic range extending from single x-rays to a full well of more than 2.6 x 107 x-rays/pixel, capable of measuring fluxes up to 108 x-rays/pixel/s, with a sub-pixel point spread. These characteristics exceed, by orders of magnitude, the capabilities of the current generation of x-ray imagers. As a consequence this imager is poised to enable a broad range of synchrotron x-ray experiments that were previously not possible.

The behavior of nanoscale materials can change rapidly with time either because the environment changes rapidly or because the influence of the environment propagates quickly across the intrinsically small dimensions of nanoscale materials. Extremely fast time resolution studies using X-rays, electrons and neutrons are of very high interest to many researchers and is a fast-evolving and interesting field for the study of dynamic processes. Therefore, in situ structural characterization and measurements of structure-property relationships covering several decades of length and time scales (from atoms to millimeters and femtoseconds to hours) with high spatial and temporal resolutions are crucially important to understand the synthesis and behavior of multidimensional materials. The techniques described in this book will permit access to the real-time dynamics of materials, surface processes and chemical and biological reactions at various time scales. This book provides an interdisciplinary reference for research using in situ techniques to capture the real-time structural and property responses of materials to surrounding fields using electron, optical and x-ray microscopies (e.g. scanning, transmission and low-energy electron microscopy and scanning probe microscopy) or in the scattering realm with x-ray, neutron and electron diffraction.