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Optical Engineering

Photoemission polarimeter in soft x-ray astronomy
Author(s): George W. Fraser; John Ernest Lees; James F. Pearson; Mark R. Sims; J. E. Spragg; Richard Willingale
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Paper Abstract

Measurements in our laboratory have recently shown that the pulse quantum yield (counts/photon) of Csl x-ray photocathodes, measured near grazing incidence, depends on the linear polarization state of the incident beam. These results have implications both for the fundamental understanding ofthe x-ray photoeffect and, since Csl is well known as a cathode material of high (unpolarized) quantum efficiency in the 0.1 to 1.0 keV band, for the development of high-throughput astronomical x-ray polarimetry. This paper, concentrating on the latter topic, describes the practical accommodation of a photoemission polarimeter at (or near) the focus of a satellite x-ray telescope. Problems of device format, instrumental polarization, and data compression are discussed with reference to the Composite X-ray Polarimeter recently proposed for the European Space Agency High Throughput Spectroscopy mission (XMM). Examples of the sensitivity of this instrument are given. In the second part of the paper, some recent laboratory measurements are presented. These concern the variation in the number of x-ray photoelectrons with the polarimetric azimuth of a Csl cathode.

Paper Details

Date Published: 1 August 1990
PDF: 9 pages
Opt. Eng. 29(8) doi: 10.1117/12.55679
Published in: Optical Engineering Volume 29, Issue 8
Show Author Affiliations
George W. Fraser, Univ. of Leicester (United Kingdom)
John Ernest Lees, Univ. of Leicester (United Kingdom)
James F. Pearson, Univ. of Leicester (United Kingdom)
Mark R. Sims, Univ. of Leicester (United Kingdom)
J. E. Spragg, Univ. of Leicester (United Kingdom)
Richard Willingale, Univ. of Leicester (United Kingdom)

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