Design of Large Low Noise Transition Edge Sensor Arrays for Future FIR Space Missions

The Astrophysics 2020 Decadal Report recommended a line of Probe missions with far-infrared imaging or spectroscopy capabilities. The achievable sensitivity of these FIR missions will be enabled by cooled telescopes and advanced cryogenic detector technologies, potentially resulting in up to three orders of magnitude improvement in sensitivity and mapping speeds up to more than a million times of those achieved so far with past missions. We have obtained NASA funding to build and demonstrate transition edge sensor (TES)-based kilopixel arrays with the properties that match the requirements for cryogenic far-infrared space missions: The arrays are very closely tileable in one direction and with a moderate gap in the other direction. This array architecture can meet the sampling and pixel number requirement of a few 10⁴ pixels. Many details of the architecture have already been demonstrated individually, and the detector board will be optimized for the use of the latest cryogenic NIST 2D time-domain SQUID readout multiplexers with a high-density fanout scheme. Additionally, we will use flex lines that are very similar to those developed at Princeton University for the ACT project. This method allows virtually unlimited tileability of the detector arrays and thus a compact detector/readout design for future FIR instrumentation requiring large pixel counts. We already have a pixel design which, if implemented with TES operating at less than 100 mK, will meet the continuum sensitivity requirements for background-limited cryogenic space missions of NEP < 10^–18 W/√Hz). Furthermore, our array design will be compatible with lower noise TES designs for spectroscopy that we are currently demonstrating in our laboratory.