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Proceedings Paper

Performance verification of the Gravity and Extreme Magnetism Small explorer (GEMS) x-ray polarimeter
Author(s): Teruaki Enoto; J. Kevin Black; Takao Kitaguchi; Asami Hayato; Joanne E. Hill; Keith Jahoda; Toru Tamagawa; Kenta Kaneko; Yoko Takeuchi; Akifumi Yoshikawa; Hannah Marlowe; Scott Griffiths; Philip E. Kaaret; David Kenward; Syed Khalid
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Paper Abstract

Polarimetry is a powerful tool for astrophysical observations that has yet to be exploited in the X-ray band. For satellite-borne and sounding rocket experiments, we have developed a photoelectric gas polarimeter to measure X-ray polarization in the 2–10 keV range utilizing a time projection chamber (TPC) and advanced micro-pattern gas electron multiplier (GEM) techniques. We carried out performance verification of a flight equivalent unit (1/4 model) which was planned to be launched on the NASA Gravity and Extreme Magnetism Small Explorer (GEMS) satellite. The test was performed at Brookhaven National Laboratory, National Synchrotron Light Source (NSLS) facility in April 2013. The polarimeter was irradiated with linearly-polarized monochromatic X-rays between 2.3 and 10.0 keV and scanned with a collimated beam at 5 different detector positions. After a systematic investigation of the detector response, a modulation factor ≥35% above 4 keV was obtained with the expected polarization angle. At energies below 4 keV where the photoelectron track becomes short, diffusion in the region between the GEM and readout strips leaves an asymmetric photoelectron image. A correction method retrieves an expected modulation angle, and the expected modulation factor, ~20% at 2.7 keV. Folding the measured values of modulation through an instrument model gives sensitivity, parameterized by minimum detectable polarization (MDP), nearly identical to that assumed at the preliminary design review (PDR).

Paper Details

Date Published: 24 July 2014
PDF: 12 pages
Proc. SPIE 9144, Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray, 91444M (24 July 2014); doi: 10.1117/12.2056841
Show Author Affiliations
Teruaki Enoto, NASA Goddard Space Flight Ctr. (United States)
RIKEN (Japan)
J. Kevin Black, NASA Goddard Space Flight Ctr. (United States)
Takao Kitaguchi, RIKEN (Japan)
Asami Hayato, RIKEN (Japan)
Joanne E. Hill, NASA Goddard Space Flight Ctr. (United States)
Keith Jahoda, NASA Goddard Space Flight Ctr. (United States)
Toru Tamagawa, RIKEN (Japan)
Tokyo Univ. of Science (Japan)
Kenta Kaneko, RIKEN (Japan)
Tokyo Univ. of Science (Japan)
Yoko Takeuchi, RIKEN (Japan)
Tokyo Univ. of Science (Japan)
Akifumi Yoshikawa, RIKEN (Japan)
Tokyo Univ. of Science (Japan)
Hannah Marlowe, The Univ. of Iowa (United States)
Scott Griffiths, The Univ. of Iowa (United States)
Philip E. Kaaret, The Univ. of Iowa (United States)
David Kenward, NASA Goddard Space Flight Ctr. (United States)
Syed Khalid, Brookhaven National Lab. (United States)


Published in SPIE Proceedings Vol. 9144:
Space Telescopes and Instrumentation 2014: Ultraviolet to Gamma Ray
Tadayuki Takahashi; Jan-Willem A. den Herder; Mark Bautz, Editor(s)

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