Curved detectors for future x-ray astrophysics missions

Future X-ray astrophysics missions will survey large areas of the sky with unparalleled sensitivity, enabled by lightweight, high-resolution optics. These optics inherently produce curved focal surfaces with radii as small as 2 m, requiring a large-area detector system that closely conforms to the curved focal surface. We have embarked on a project using a curved CCD detector technology developed at MIT Lincoln Laboratory to provide large-format, curved detectors for such missions, improving performance and simplifying design. We present the current status of this work, which aims to curve back-illuminated, large-format (5 cm x 4 cm) CCDs to 2.5-m radius and confirm X-ray performance. We detail the design of fixtures and the curving process, including models showing that the process will not exceed the fracture stress or have significant effects on electrical properties. We present results on curving monitor devices and characterizing the surface geometric accuracy. We finally show X-ray performance measurements of planar CCDs that will serve as a baseline to evaluate the curved detectors, in particular the spectroscopic performance in the soft X-ray band.