Development of a Transition-Edge Sensor Anti-Coincidence Detector for a Probe Class Mission

The Light Element Mapper (LEM), a probe class mission proposal slated for submission in 2023, combines a large X-ray optic with an extremely large format microcalorimeter array to probe the physics of galaxy formation with a grasp 22x greater than ATHENA and 7x greater than Lynx. The focal plane for LEM requires a larger anti-coincidence detector than the other missions while maintaining or exceeding their high-speed response, presenting a challenge for claiming technical readiness at the time of the announcement of opportunity (AO). We will perform a rapid demonstration in the next year including design, fabrication and integration and test of a high-fidelity transition-edge sensor (TES) based device at a scale suitable for LEM.