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Proceedings Paper

Conceptual design of a fast soft x-ray stellar polarimeter
Author(s): Herman L. Marshall
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Paper Abstract

Multilayer coatings make it possible to create soft x-ray (0.25 keV) optics with large graze angles which are necessary for designing efficient polarimeters. If the detector is placed out of focus, then stellar images will take the shape of the front aperture, which would show intensity variations if the source is polarized. Two basic designs are considered. The first uses a single parabolic optic with graze angles from 25 degree(s) to 40 degree(s) and the second uses a Cassegrain telescope with angles centered at 45 degree(s). The former gives higher reflectivity at the expense of wide-field imaging, which may be sacrificed when the source region is not crowded, while the second telescope allows for off-axis use as a spectropolarimeter but has reduced throughput. A simple imaging proportional counter would be used as a detector and the overall sensitivity of the first design would be high enough to measure the polarization of the bright BL Lac object, PKS 2155-304, to an accuracy of 3% during a rocket flight. A small satellite would be capable of measuring several hundred polarizations with an uncertainty of 1% per year.

Paper Details

Date Published: 7 November 1994
PDF: 10 pages
Proc. SPIE 2283, X-Ray and Ultraviolet Spectroscopy and Polarimetry, (7 November 1994); doi: 10.1117/12.193206
Show Author Affiliations
Herman L. Marshall, Massachusetts Institute of Technology (United States)

Published in SPIE Proceedings Vol. 2283:
X-Ray and Ultraviolet Spectroscopy and Polarimetry
Silvano Fineschi, Editor(s)

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