Advanced STJ-based X-Ray Spectrometer for Synchrotron Science Applications

A new class of soft X-ray detectors based on superconducting tunnel junctions that offers both excellent energy resolution as well as high count rate capabilities is now becoming available. These advanced detectors operate at around 0.3 K and require a cryogenic refrigeration system and temperature control electronics for operation at this temperature, along with room-temperature readout electronics and software for spectral analysis. To be viable as an instrument for users at synchrotron beam lines, however, it is essential that the cryogenics and basic system operation be completely transparent to the user. Currently, complete turn-key cryogen-free spectrometers instrumented with STJ detectors are not available commercially. Cryogen-free refrigeration systems consisting of a two-stage pulse tube cryocooler and adiabatic demagnetization refrigerator (ADR) offer a convenient means to reach temperatures below 0.05 K with long working times (nearly 20 hours at 0.1 K). Such cryogenic systems are ideally suited for the proposed spectrometer development effort. The complete cryostat design for the spectrometer was successfully completed during Phase I, including the sourcing of all key components. During Phase II, STAR Cryoelectronics proposes to build a turn-key, cryogen-free ADR cryostat with automated controls based on the design work completed during Phase I that will be instrumented with a 112 pixel STJ detector array for synchrotron science applications. Commercial Applications and Other Benefits: X-ray absorption spectroscopy (XAS) is used to study the local molecular and electronic structure of specific elements. Samples can be highly diluted and generally do not require substantial pre-treatment and can range from chemicals and biological samples or tissues to soils and rocks. The development and commercialization of the advanced STJ-based X-ray spectrometer will meet growing needs for improved detector instrumentation for applications in synchrotron science such as XAS. The significant performance enhancements the proposed STJ-based X-ray spectrometer will lead to greater scientific productivity and return on the Nations substantial capital investment in synchrotron facilities.