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

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 90° 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. Furthermore, reflectance and transmission measurements of BRP prototype elements closely match theoretical predictions, both before and after rigorous environmental testing.
Authors:
 [1] ;  [1] ;  [2] ;  [2] ;  [2] ;  [2] ;  [3]
  1. Univ. of Iowa, Iowa City, IA (United States)
  2. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
  3. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Publication Date:
OSTI Identifier:
1266681
Report Number(s):
LLNL-JRNL--643684
Journal ID: ISSN 0922-6435
Grant/Contract Number:
AC52-07NA27344
Type:
Accepted Manuscript
Journal Name:
Experimental Astronomy
Additional Journal Information:
Journal Volume: 36; Journal Issue: 1-2; Journal ID: ISSN 0922-6435
Publisher:
Springer
Research Org:
Lawrence Livermore National Laboratory (LLNL), Livermore, CA (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 79 ASTRONOMY AND ASTROPHYSICS; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS multilayers; X-ray polarimetry; beamsplitters; thin films