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Proceedings Paper

Laboratory calibration of x-ray transmission diffraction gratings
Author(s): Daniel Dewey; Donald N. Humphries; G. Y. McLean; David A. Moschella
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Paper Abstract

The 336 individual grating elements making up the High-Energy Transmission Grating (HETG) will be verified and calibrated in laboratory facilities at MIT as they are fabricated. A high instrument resolving power of order E/(Delta) E approximately equals 1000 requires an overall period uniformity of better than 250 ppm. To extract the maximum astrophysical information the diffraction efficiency of the HETG will be calibrated to the 1% level (1(sigma) ). Grating element period variations are measured and mapped in the Laser Reflection facility. Collimated HeCd (3250- angstrom) or HeNe (6328-angstrom) laser light is diffracted by the samples and measured. A per-point measurement noise of below 5 ppm rms and an overall period repeatability of 40 ppm rms have been achieved. X-ray diffraction efficiency in the 0.4 to 10 keV range is calibrated in the X-ray Grating Evaluation Facility (X- GEF). The facility combines a 17 meter vacuum beam line, a multi- anode X-ray source with monitor counter, a piezo-deformed 1D Ir coated focussing optic, a single-pixel solid state detector, and a 2D imaging proportional counter. The facility operation is under computer control and test procedures, instrumentation parameters, and acquired data are managed with a database. The system uses synchrotron-calibrated reference gratings as efficiency transfer standards. Detailed characterization and modeling of the X-GEF components and test/analysis procedures are being carried out to optimize the quality of the HETG calibration.

Paper Details

Date Published: 16 September 1994
PDF: 15 pages
Proc. SPIE 2280, EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy V, (16 September 1994); doi: 10.1117/12.186817
Show Author Affiliations
Daniel Dewey, Massachusetts Institute of Technology (United States)
Donald N. Humphries, Mech Tek (United States)
G. Y. McLean, Univ. of Calif./Berkeley (United States)
David A. Moschella, Ellipsis (United States)

Published in SPIE Proceedings Vol. 2280:
EUV, X-Ray, and Gamma-Ray Instrumentation for Astronomy V
Oswald H. W. Siegmund; John V. Vallerga, Editor(s)

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