Abstract:

We present the status of a hard X-ray (up to 20 keV) transition-edge sensor (TES) spectrometer being developed for the Advanced Photon Source (APS). The spectrometer will consist of interchangeable application-specific TES arrays fabricated at ANL, which will be read out with microwave-multiplied SQUIDs fabricated at NIST. Two example of applications are hard X-ray emission spectroscopy (XES) and X-ray absorption fine structure (XAFS). High-resolution XES measurements of the K and K emission lines can give precise information on the molecular orbitals and population of the electronic bands important in bonding, magnetism, and electronic properties of the transition metals and other heavy elements. XAFS can provide detailed chemical and structural information about very dilute components of a sample when moderate energy resolution TES are combined with pre-filtering X-ray optics. Different applications require different sensors characteristics, for XES experiments energy resolution is the most important requirement while XAFS requires moderate energy resolution at much higher count rates. For these reasons, developing the capability to fabricate application-specific sensor is crucial. The project is currently focusing to develop a 100-pixels array optimized for XES, followed by the development of an array for XAFS. Details on the instrument, such as sensor design, readout electronics and cryogenic solutions, will be provided.