LARGE SOLID ANGLE SPECTROMETER FOR SYNCHROTRON MICROBEAM - DESCRIPTION (provided by applicant): We will develop a new x-ray spectrometer that will offer high count rate, excellent energy resolution, and large solid angle for the demanding performance requirements encountered in synchrotron x-ray microprobes and nanoprobes currently in operation and being built at the nation's synchrotron facilities. These x-ray microbeams have opened up new avenues of research in the biology, materials science, and chemistry in the analysis of chemical and biological structures on the nano-scale. Commensurate with the development of the experimental techniques needs to be a development of the x-ray detectors to match the capabilities of the x-ray microprobe beams. The proposed x-ray spectrometer will be based on Photon Imaging's new multi-cathode detector technology, specifically designed in an annular multi-element array format. Due to the novel configuration of the detector elements, the spectrometer will cover a large solid angle, offer improved signal collection capabilities, higher count rate capability and, very importantly, it will offer the vastly improved flexibility of design as it does not require cryogenic cooling. During the Phase I, we will design a 4-channel annular spectrometer; select the detectors, design and fabricate the low-noise readout electronics, and assemble and characterize the spectrometer with radioisotope sources and an x-ray generator. Phase II will include the development of a monolithic multi-element detector (6 or more channels), which will eliminate the undesirable dead area surrounding the single element devices utilized in Phase I, thereby further increasing the solid angle. The Phase II will also include refinement of the spectrometer mechanical design. The full 6 (or more) channels will be outfitted with custom preamplifiers, multi-channel amplifiers and ADCs. Software will be developed for the computer-based calibration of the individual channels and for multi-plexing of the signals into one output. The spectrometer will be fully characterized in an x-ray microprobe experiment at the Advanced Photon Source, in collaboration with Argonne National Laboratory staff.
