Optical Calibration of a Frequency-Domain-Multiplexed X-Ray TES Microcalorimeter Array via Photon-Number-Resolved Statistics
Transition-edge sensor (TES) microcalorimeters for future X-ray space observatories require accurate low-energy calibration, a regime where conventional X-ray sources are limited by intrinsic linewidth, count rate, or experimental complexity. In this work, we investigate fiber-coupled optical photons as a compact calib...