Detector Design and Development for the Line Emission Mapper (LEM) Observatory

The Line Emission Mapper (LEM) is a probe-class mission concept under study by SAO and NASA that is designed to provide unprecedented insight into the physics of galaxy formation, including stellar and black-hole feedback and flows of baryonic matter into and out of galaxies. LEM incorporates a light-weight X-ray optic with 10” angular resolution and a large-format microcalorimeter array with a 15” pixel pitch over a 29’ field of view (FOV). A microcalorimeter-based anti-coincidence detector is placed behind this array to distinguish cosmic-ray particle events from the science photons. The main microcalorimeter array and readout design takes advantage of mature technology (approaching TRL-5) that has been developed for Athena X-IFU. The central 9’ region of the array consists of 1k transition-edge sensors (TESs), for a bandpass of 0.2-2 keV and an energy resolution of 1 eV at 1 keV. The rest of the FOV is covered by 4-pixel TES hydras with 2 eV energy resolution at 1 keV. Hydras are position-sensitive (‘thermally multiplexed’) detectors that enable extremely large numbers of effective pixels in an array (with some compromise in performance), without a commensurate increase in the number of wires, bias circuit, and readout components. In total the array will have 4k TESs with 14k imaging elements on a 290 micron-pitch. The array will be read out with state-of-the-art time-division multiplexing (TDM). Here we present a detailed overview of the baseline microcalorimeter detector and describe how we are leveraging the design and development of the Athena-X-IFU components of high technical readiness level, to meet the LEM performance requirements. We will discuss the current status and plan for continued LEM detector development.