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Proceedings Paper

Methods for reducing singly reflected rays on the Wolter-I focusing mirrors of the FOXSI rocket experiment
Author(s): Juan Camilo Buitrago-Casas; Ronald Elsner; Lindsay Glesener; Steven Christe; Brian Ramsey; Sasha Courtade; Shin-nosuke Ishikawa; Noriyuki Narukage; Paul Turin; Juliana Vievering; P. S. Athiray; Sophie Musset; Säm Krucker
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Paper Abstract

In high energy solar astrophysics, imaging hard X-rays by direct focusing offers higher dynamic range and greater sensitivity compared to past techniques that used indirect imaging. The Focusing Optics X-ray Solar Imager (FOXSI) is a sounding rocket payload that uses seven sets of nested Wolter-I figured mirrors together with seven high-sensitivity semiconductor detectors to observe the Sun in hard X-rays through direct focusing. The FOXSI rocket has successfully flown twice and is funded to fly a third time in summer 2018. The Wolter-I geometry consists of two consecutive mirrors, one paraboloid and one hyperboloid, that reflect photons at grazing angles. Correctly focused X-rays reflect once per mirror segment. For extended sources, like the Sun, off-axis photons at certain incident angles can reflect on only one mirror and still reach the focal plane, generating a background pattern of singly reflected rays (i.e., ghost rays) that can limit the sensitivity of the observation to faint, focused sources. Understanding and mitigating the impact of the singly reflected rays on the FOXSI optical modules will maximize the instruments’ sensitivity to background-limited sources. We present an analysis of the FOXSI singly reflected rays based on ray-tracing simulations and laboratory measurements, as well as the effectiveness of different physical strategies to reduce them.

Paper Details

Date Published: 29 August 2017
PDF: 15 pages
Proc. SPIE 10399, Optics for EUV, X-Ray, and Gamma-Ray Astronomy VIII, 103990J (29 August 2017); doi: 10.1117/12.2274675
Show Author Affiliations
Juan Camilo Buitrago-Casas, Univ. of California, Berkeley (United States)
Ronald Elsner, NASA Marshall Space Flight Ctr. (United States)
Lindsay Glesener, Univ. of Minnesota, Twin Cities (United States)
Steven Christe, NASA Goddard Space Flight Ctr. (United States)
Brian Ramsey, NASA Marshall Space Flight Ctr. (United States)
Sasha Courtade, Univ. of California, Berkeley (United States)
Shin-nosuke Ishikawa, Institute of Space and Astronautical Science (Japan)
Noriyuki Narukage, National Astronomical Observatory of Japan (Japan)
Paul Turin, Univ. of California, Berkeley (United States)
Juliana Vievering, Univ. of Minnesota, Twin Cities (United States)
P. S. Athiray, Univ. of Minnesota, Twin Cities (United States)
Sophie Musset, Univ. of Minnesota, Twin Cities (United States)
Säm Krucker, Univ. of California, Berkeley (United States)
Univ. of Applied Sciences Northwest (Switzerland)


Published in SPIE Proceedings Vol. 10399:
Optics for EUV, X-Ray, and Gamma-Ray Astronomy VIII
Stephen L. O'Dell; Giovanni Pareschi, Editor(s)

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