Optimization of thermal kinetic inductance detectors for x-ray spectroscopy

Thermal kinetic inductance detectors (TKIDs) are promising new detectors for use in X-ray spectroscopy because of the relative ease with which they can be fabricated into large arrays. While initial results have hinted at their resolution capability, the ultimate resolution achievable with these detectors has not been described. Using a bolometer matrix formalism, we examine the parameter space of the detector design (i.e., film critical temperature, detector operating temperature, resonator coupling, etc.) to examine the detectors response to noise sources, including phonon, Johnson, bias, and amplifier noise. Finally, we present the design of TKID optimized for 6-keV X-ray spectroscopy.