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A soft X-ray beam-splitting multilayer optic for the NASA GEMS Bragg Reflection Polarimeter
Journal article   Open access   Peer reviewed

A soft X-ray beam-splitting multilayer optic for the NASA GEMS Bragg Reflection Polarimeter

Ryan Allured, Mónica Fernández-Perea, Regina Soufli, Jennifer B Alameda, Michael J Pivovaroff, Eric M Gullikson and Philip Kaaret
Experimental astronomy, Vol.36(1-2), pp.371-388
04/12/2013
DOI: 10.1007/s10686-013-9337-2

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Abstract

A soft X-ray, beam-splitting, multilayer optic has been developed for the Bragg Reflection Polarimeter (BRP) on the NASA Gravity and Extreme Magnetism Small Explorer Mission (GEMS). The optic is designed to reflect 0.5 keV X-rays through a angle to the BRP detector, and transmit 2–10 keV X-rays to the primary polarimeter. The transmission requirement prevents the use of a thick substrate, so a 2 μm thick polyimide membrane was used. Atomic force microscopy has shown the membrane to possess high spatial frequency roughness less than 0.2 nm rms, permitting adequate X-ray reflectance. A multilayer thin film was especially developed and deposited via magnetron sputtering with reflectance and transmission properties that satisfy the BRP requirements and with near-zero stress. Reflectance and transmission measurements of BRP prototype elements closely match theoretical predictions, both before and after rigorous environmental testing.
Astronomy Computer Science Physics Chemistry and Earth Sciences Observations and Techniques Original Article Physics and Astronomy Statistics for Engineering

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