Development of High Efficiency High Resolution Cryogenic Detector for X-ray Fluorescence Applications and Student Training

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X-ray detection is often the limiting factor in modern synchrotron-based fluorescence experiments in material science and biophysics. The brightness available from synchrotron radiation sources has increased by nearly 10 orders of magnitude in the past 20 years, but our ability to collect and discriminate emitted x-rays has not kept pace. This award from the Instrumentation for Materials Research program to the University of California Davis will support new detector development which will greatly enhance the sensitivity of existing instrumentation for fluorescence analysis of thin films or dilute samples in material science and biophysics. This instrument development will adapt existing cryogenic detectors to the specific needs of synchrotron experiments. The origin of the spectral artifacts that presently limit the sensitivity to certain emission lines will be studied and addressed. The current detector's usable energy range will be extended beyond one kilo electronvolt by adding thick absorber films of high Z materials. The total area and count rate capabilities of the sensor will be increased by increasing This development will be done by graduate students and postdoctoral fellows in collaboration with the Advanced Detector Group at Lawrence Livermore. The cryogenic spectrometer will be available to collaborators on a proposal basis. Combining such high-sensitivity high-resolution detectors with the intensity of undulator radiation of third generation synchrotrons will open up a range of new experimental methods for previously unfeasible science. Graduate students will focus on two sets of experiments. They will develop angle-resolved soft x-ray fluorescence spectroscopy for non-destructive depth profiling of thin film samples. They will also extend fluorescence-detected L-edge absorption spectroscopy to vanadium and manganese-containing metalloenzymes to determine the chemical oxidation state of the metal site during the catalytic cycle. The long-term goal is to combine non-destructive depth profiling and in-situ chemical characterization of samples with part per million level sensitivity.X-ray detection is often the limiting factor in modern synchrotron-based fluorescence experiments in material science and biophysics. The brightness available from synchrotron radiation sources has increased by nearly 10 orders of magnitude in the past 20 years, but our ability to collect and discriminate emitted x-rays has not kept pace. This award from the Instrumentation for Materials Research program to the University of California Davis will support new detector development which will greatly enhance the sensitivity of existing instrumentation for fluorescence analysis of thin films or dilute samples in material science and biophysics. This instrument development will adapt existing cryogenic detectors to the specific needs of synchrotron experiments. The development will be done by graduate students and postdoctoral fellows in collaboration with the Advanced Detector Group at Lawrence Livermore. The cryogenic spectrometer will be available to collaborators on a proposal basis. Combining such high-sensitivity high-resolution detectors with the intensity of undulator radiation of third generation synchrotrons will open up a range of new experimental methods for previously unfeasible science. Graduate students will focus on two sets of experiments. The long-term goal is to combine non-destructive depth profiling and in-situ chemical characterization of samples with part per million level sensitivity.