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Proceedings Paper

Angular resolution measurements at SPring-8 of a hard x-ray optic for the New Hard X-ray Mission
Author(s): D. Spiga; L. Raimondi; A. Furuzawa; S. Basso; R. Binda; G. Borghi; V. Cotroneo; G. Grisoni; H. Kunieda; F. Marioni; H. Matsumoto; H. Mori; T. Miyazawa; B. Negri; A. Orlandi; G. Pareschi; B. Salmaso; G. Tagliaferri; K. Uesugi; G. Valsecchi; D. Vernani
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Paper Abstract

The realization of X-ray telescopes with imaging capabilities in the hard (> 10 keV) X-ray band requires the adoption of optics with shallow (< 0.25 deg) grazing angles to enhance the reflectivity of reflective coatings. On the other hand, to obtain large collecting area, large mirror diameters (< 350 mm) are necessary. This implies that mirrors with focal lengths ≥10 m shall be produced and tested. Full-illumination tests of such mirrors are usually performed with onground X-ray facilities, aimed at measuring their effective area and the angular resolution; however, they in general suffer from effects of the finite distance of the X-ray source, e.g. a loss of effective area for double reflection. These effects increase with the focal length of the mirror under test; hence a "partial" full-illumination measurement might not be fully representative of the in-flight performances. Indeed, a pencil beam test can be adopted to overcome this shortcoming, because a sector at a time is exposed to the X-ray flux, and the compensation of the beam divergence is achieved by tilting the optic. In this work we present the result of a hard X-ray test campaign performed at the BL20B2 beamline of the SPring-8 synchrotron radiation facility, aimed at characterizing the Point Spread Function (PSF) of a multilayer-coated Wolter-I mirror shell manufactured by Nickel electroforming. The mirror shell is a demonstrator for the NHXM hard X-ray imaging telescope (0.3 - 80 keV), with a predicted HEW (Half Energy Width) close to 20 arcsec. We show some reconstructed PSFs at monochromatic X-ray energies of 15 to 63 keV, and compare them with the PSFs computed from post-campaign metrology data, self-consistently treating profile and roughness data by means of a method based on the Fresnel diffraction theory. The modeling matches the measured PSFs accurately.

Paper Details

Date Published: 1 October 2011
PDF: 12 pages
Proc. SPIE 8147, Optics for EUV, X-Ray, and Gamma-Ray Astronomy V, 81470A (1 October 2011); doi: 10.1117/12.894488
Show Author Affiliations
D. Spiga, INAF - Osservatorio Astronomico di Brera (Italy)
L. Raimondi, INAF - Osservatorio Astronomico di Brera (Italy)
Univ. degli Studi dell' Insubria (Italy)
A. Furuzawa, Nagoya Univ. (Japan)
S. Basso, INAF - Osservatorio Astronomico di Brera (Italy)
R. Binda, Media Lario Technologies (Italy)
G. Borghi, Media Lario Technologies (Italy)
V. Cotroneo, Harvard-Smithsonian Ctr. for Astrophysics (United States)
G. Grisoni, Media Lario Technologies (Italy)
H. Kunieda, Nagoya Univ. (Japan)
F. Marioni, Media Lario Technologies (Italy)
H. Matsumoto, Nagoya Univ. (Japan)
H. Mori, Nagoya Univ. (Japan)
T. Miyazawa, Nagoya Univ. (Japan)
B. Negri, Agenzia Spaziale Italiana (Italy)
A. Orlandi, Media Lario Technologies (Italy)
G. Pareschi, INAF - Osservatorio Astronomico di Brera (Italy)
B. Salmaso, INAF - Osservatorio Astronomico di Brera (Italy)
G. Tagliaferri, INAF - Osservatorio Astronomico di Brera (Italy)
K. Uesugi, Japan Synchrotron Radiation Research Institute (Japan)
G. Valsecchi, Media Lario Technologies (Italy)
D. Vernani, Media Lario Technologies (Italy)

Published in SPIE Proceedings Vol. 8147:
Optics for EUV, X-Ray, and Gamma-Ray Astronomy V
Stephen L. O'Dell; Giovanni Pareschi, Editor(s)

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