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Proceedings Paper

An examination of the sensitivity and systematic error of the NASA GEMS Bragg Reflection Polarimeter using Monte-Carlo simulations
Author(s): Ryan Allured; Takashi Okajima; Regina Soufli; Mónica Fernández-Perea; Ryan O. Daly; Hannah Marlowe; Scott T. Griffiths; Michael J. Pivovaroff; Philip Kaaret
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Paper Abstract

The Bragg Reflection Polarimeter (BRP) on the NASA Gravity and Extreme Magnetism Small Explorer Mission is designed to measure the linear polarization of astrophysical sources in a narrow band centered at about 500 eV. X-rays are focused by Wolter I mirrors through a 4.5 m focal length to a time projection chamber (TPC) polarimeter, sensitive between 2{10 keV. In this optical path lies the BRP multilayer reflector at a nominal 45 degree incidence angle. The reflector reflects soft X-rays to the BRP detector and transmits hard X-rays to the TPC. As the spacecraft rotates about the optical axis, the reflected count rate will vary depending on the polarization of the incident beam. However, false polarization signals may be produced due to misalignments and spacecraft pointing wobble. Monte-Carlo simulations have been carried out, showing that the false modulation is below the statistical uncertainties for the expected focal plane offsets of <~ 2 mm.

Paper Details

Date Published: 19 October 2012
PDF: 11 pages
Proc. SPIE 8487, Novel Optical Systems Design and Optimization XV, 848703 (19 October 2012); doi: 10.1117/12.930065
Show Author Affiliations
Ryan Allured, The Univ. of Iowa (United States)
Takashi Okajima, NASA Goddard Space Flight Ctr. (United States)
Regina Soufli, Lawrence Livermore National Lab. (United States)
Mónica Fernández-Perea, Lawrence Livermore National Lab. (United States)
Ryan O. Daly, The Univ. of Iowa (United States)
Hannah Marlowe, The Univ. of Iowa (United States)
Scott T. Griffiths, The Univ. of Iowa (United States)
Michael J. Pivovaroff, Lawrence Livermore National Lab. (United States)
Philip Kaaret, The Univ. of Iowa (United States)


Published in SPIE Proceedings Vol. 8487:
Novel Optical Systems Design and Optimization XV
G. Groot Gregory; Arthur J. Davis, Editor(s)

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