Superconducting Tunnel Junction Detectors for High-Resolution X-Ray Spectroscopy

X-ray absorption spectroscopy is a widely used experimental technique for studying the composition and chemistry of materials and is one of the driving forces behind the explosive growth of synchrotron light sources and their increase in brightness by many orders of magnitude. However, advances in detector technology have not kept pace with advances in synchrotron brightness, leading to limitations on scientific output and research capabilities. In Phase I, STAR Cryoelectronics developed an innovative and streamlined process for the fabrication of high energy resolution, high count rate superconducting tunnel junction (STJ) X- ray detectors based on Ta thin films that will meet growing needs for advanced detectors for synchrotron science applications. Several prototype STJ detectors and detector arrays were successfully fabricated and characterized during Phase I. Record energy resolution has been achieved, and multi-pixel arrays with up to 112 pixels were successfully fabricated. During Phase II, STAR Cryoelectronics plans to further improve energy resolution, increase the maximum count rate per pixel, and enhance production yield and detector reliability. Commercial Applications and Other Benefits: The new STJ detector arrays represent the enabling technology for two significant commercial applications: X-ray absorption spectroscopy (XAS) at the synchrotron, which is used to study the local molecular and electronic structure of specific elements, and X-ray microanalysis in conjunction with a scanning electron microscope (SEM), which is used for defect and failure analysis. XAS samples can be highly diluted and generally do not require substantial pre- treatment, and they can range from chemicals and biological samples or tissues to soils and rocks. The development and commercialization of multi-pixel arrays of advanced STJ X-ray detectors will meet growing needs for improved detector instrumentation for applications in synchrotron science such as XAS. The significant performance enhancements that will be realized with the proposed STJ X-ray detector arrays will lead to greater scientific productivity and return on the Nations substantial capital investment in synchrotron facilities.