Thermal Crosstalk in 24-Pixel Hard X-Ray TES Arrays: Comparative Experiments and Multibody Simulations

In this study, we conducted simulations and experimental characterization of thermal crosstalk in a hard X-ray transition-edge sensor (TES) array. TESs are low-temperature superconducting detectors with excellent energy resolution, making them ideal for synchrotron applications. To achieve the required count rate and collecting area, TES detectors are typically organized into multi-pixel arrays. However, tight pixel spacing and multiplexing can introduce thermal and electrical crosstalk that degrades spectral resolution at high photon rates. We characterized the crosstalk phenomena between X-ray TESs in a 24-pixel array. This TES array, fabricated at the Argonne National Laboratory (ANL), is designed to operate in the tens of keV regime. In prior work, we experimentally developed procedures and algorithms to identify and quantify crosstalk in various setups. To further explain the phenomenon, we created a multibody model to simulate the thermal crosstalk response between neighboring TES pixels. Simulations correlate the observed thermal crosstalk with key device properties: material composition, TES transition shape parameters ($\alpha$and$\beta$), and intrinsic characteristics such as heat capacity and thermal conductance.