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Description
Conventional semiconductor-based energy-dispersive spectrometers offer high detection efficiency but relatively limited energy resolution, whereas crystal-based wavelength-dispersive spectrometers can achieve excellent energy resolution at the cost of collection efficiency and simultaneous spectral coverage. Transition-edge sensor (TES) microcalorimeters can combine high energy resolution, high detection efficiency, and broadband spectroscopic capability.
This work describes the development of a TES-based hard X-ray spectrometer, including aluminum–manganese (AlMn) TES design, absorber optimization, electrothermal characterization, and system-level design and simulation. The spectrometer targets an energy resolving power of (E/\Delta E \sim 2000) over the 10–100 keV energy range. TES devices exploit the steep resistance–temperature dependence within the superconducting transition to resolve the small temperature rise produced by an absorbed photon. The transition temperature (T_\mathrm{c}) of AlMn films can be adjusted by annealing, which facilitates control of (T_\mathrm{c}) and its uniformity across detector arrays. A gold–bismuth bilayer absorber is used to combine the high thermal conductivity of gold with the relatively low heat capacity and high X-ray stopping power of bismuth. The absorber geometry and TES–absorber coupling are optimized for efficient thermalization while reducing position-dependent response and maintaining a balance between energy resolution and absorption efficiency. Electrothermal measurements are used to characterize device performance and guide further detector optimization and cryogenic system integration.
The development can be used for applications in hard X-ray Compton spectroscopy and X-ray emission spectroscopy at synchrotron radiation facilities. The TES detector can also be used for 511-keV positron-annihilation spectroscopy of the Galactic center.
