Development of TES Microcalorimeter Arrays for the Micro-X Sounding Rocket Experiment

The Micro-X sounding rocket program will fly a 128-pixel array of transition-edge-sensor microcalorimeters to enable high-resolution X-ray imaging spectroscopy of supernova remnants. To match the angular resolution of the optics while maximizing the field-of-view and retaining a high energy resolution (2-4 eV at 1 keV), we have designed the pixels using 590 × 590 μm² Au/Bi absorbers, which overhang 140 × 140 μm² Mo/Au sensors. Here we report experimental results from flight-candidate arrays, including measurements of energy resolution, uniformity, and absorber thermalization. We describe the reduction in pixel-to-pixel crosstalk afforded by an angle-evaporated Cu backside heatsinking layer, which provides Cu coverage on the four sidewalls of the silicon wells beneath each pixel. In addition, we present measurements of devices that have an identical pixel architecture but were fabricated with thin (sub-micron) all-Au absorbers.