Development of CCDs for REXIS on OSIRIS-REx
Author(s)Ryu, Kevin K.; Burke, Barry E.; Lambert, Renee D.; Suntharalingam, Vyshnavi; Ward, Christopher M.; Warner, Keith; Masterson, Rebecca A.; O'Brien, Peter W.; Bautz, Marshall W.; Kissel, Steve E.; Binzel, Richard P; Clark Jr, Harry R.; ... Show more Show less
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The Regolith x-ray Imaging Spectrometer (REXIS) is a coded-aperture soft x-ray imaging instrument on the OSIRIS-REx spacecraft to be launched in 2016. The spacecraft will fly to and orbit the near-Earth asteroid Bennu, while REXIS maps the elemental distribution on the asteroid using x-ray fluorescence. The detector consists of a 2×2 array of backilluminated 1k×1k frame transfer CCDs with a flight heritage to Suzaku and Chandra. The back surface has a thin p[superscript +]-doped layer deposited by molecular-beam epitaxy (MBE) for maximum quantum efficiency and energy resolution at low x-ray energies. The CCDs also feature an integrated optical-blocking filter (OBF) to suppress visible and near-infrared light. The OBF is an aluminum film deposited directly on the CCD back surface and is mechanically more robust and less absorptive of x-rays than the conventional free-standing aluminum-coated polymer films. The CCDs have charge transfer inefficiencies of less than 10[superscript -6], and dark current of 1e-/pixel/second at the REXIS operating temperature of –60 °C. The resulting spectral resolution is 115 eV at 2 KeV. The extinction ratio of the filter is ~10[superscript 12] at 625 nm.
DepartmentLincoln Laboratory; Massachusetts Institute of Technology. Department of Aeronautics and Astronautics; Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences; MIT Kavli Institute for Astrophysics and Space Research
Proceedings of SPIE--the International Society for Optical Engineering
Ryu, Kevin K., Barry E. Burke, Harry R. Clark, Renee D. Lambert, Peter O’Brien, Vyshnavi Suntharalingam, Christopher M. Ward, et al. “Development of CCDs for REXIS on OSIRIS-REx.” Edited by Tadayuki Takahashi, Jan-Willem A. den Herder, and Mark Bautz. Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray (July 24, 2014).
Author's final manuscript