Ground calibration of the x-ray mirror assembly for the x-ray imaging and spectroscopy mission (XRISM) III-performance variation across the aperture

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Takayuki Hayashi, Rozenn Boissay-Malaquin, Keisuke Tamura, Takashi Okajima, Toshiki Sato, Lawrence Olsen, Richard Koenecke, Wilson Lara, Leor Bleier, Maurice Leutenegger, Megan Eckart, Tahir Yaqoob, and Meng Chiao "Ground calibration of the x-ray mirror assembly for the x-ray imaging and spectroscopy mission (XRISM) III-performance variation across the aperture", Proc. SPIE 12181, Space Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray, 121815Y (31 August 2022); https://doi.org/10.1117/12.2627975

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This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
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Abstract

A measurement called “local spot scan (LSS)” reveals the detailed local performance of the X-ray Mirror Assembly (XMA) of the XRISM satellite. A 6.4 keV 10 mm×10 mm pencil beam was tiled across the mirror aperture. We extracted three local performance metrics at each spot: effective area (EA), image shift, and image profile. The EA maps on the aperture of all the quadrants (QTs) are quantitatively very similar to each other. The inner region has two times larger local EA than the outer one because of the difference in reflectivity at shallower incident angles. The pattern of the image shift is different per QT. The pattern indicates systematic shifts of reflectors by the reflector alignment structures rather than random shifts, and most area of the XMA aperture has a longer focal length than the design. The image profile was quantified using the Half Power Diameter (HPD). There is much less variation in the HPD maps than in the image shift. The inner region has better HPD because of its better conical approximation and figure error of the reflectors. Patterns visible in the HPD maps are associated with alignment structures at a certain radial range. The local performances acquired by the LSS will be compiled into the Calibration Data Base (CalDB) files.