Toward 100,000-Pixel Microcalorimeter Arrays Using Multi-absorber Transition-Edge Sensors

We report on the development of multi-absorber transition-edge sensors (TESs), referred to as ‘hydras’. A hydra consists of multiple X-ray absorbers each with a different thermal conductance to a TES. Position information is encoded in the pulse shape. With some trade-off in performance, hydras enable very large format arrays without the prohibitive increase in bias and readout components associated with arrays of individual TESs. Hydras are under development for the next generation of space telescope such as Lynx. Lynx is a NASA concept under study that will combine a < 1″ angular resolution optic with 100,000-pixel microcalorimeter array with energy resolution of Δ E FWHM ~ 3 eV in the soft X-ray energy range. We present first results from hydras with 25-pixels for Lynx. Designs with absorbers on a 25 μm and 50 μm pitch are studied. Arrays incorporate, for the first time, microstrip buried wiring layers of suitable pitch and density required to readout a full-scale Lynx array. The resolution from the coadded energy histogram including all 25-pixels was Δ E FWHM = 1.66 ± 0.02 eV and 3.34 ± 0.06 eV at an energy of 1.5 keV for the 25 μm and 50 μm absorber designs, respectively. Position discrimination is demonstrated from parameterization of the rise-time.