Electronics for Large Superconducting Tunnel Junction Detector Arrays for Synchrotron Soft X-Ray Research

The Department of Energy has spent billions of dollars over the past two decades building, staffing, and equipping four national synchrotron radiation facilities to support advanced research in all fields. Although these facilities can supply intense, brilliant x-ray beams covering a wide range of energies, x-ray detector development has not kept pace. For example, x-ray fluorescence spectroscopy is one of the most successful research techniques in the energy range from 2-20 KeV; however, the solid-state energy-dispersive detectors used for that research do not have sufficient energy resolution to allow the same methods to be applied in the range 0.2-2 KeV, in spite of the fact that much important science could be done in that range. The past 5-10 years has seen the development of superconducting tunnel junction (STJ) detectors that are capable of delivering 10-20 eV energy resolution at high count rates in this soft x-ray regime; however, the small size of these detectors (200 µm x 200 µm) require arrays of hundreds or thousands to be used effectively. This project will develop low-cost easy-to-use electronics to support such large arrays cost-effectively. In Phase I, an ultra-compact low-noise preamplifier will be built and coupled to an existing digital processor. Commercial Applications and other Benefits as described by the awardee: These detectors should: (1) allow the nation's synchrotron facilities to significantly enhance the scientific return on their investment in x-ray sources by opening up the soft x-ray regime to fluorescence analysis techniques; and (2) benefit the semiconductor industry by providing detectors optimized for very low voltage scanning electron microscopy, thereby providing a superior way to study manufacturing defects. The electronics should be delivered at $250/detector or less, allowing an array of 1,000 elements to be purchased for the same price as detectors now used in the hard x-ray regime, while delivering hundreds of times more counts with at least 5 times better energy resolution.