&lt;title&gt;Molecular contamination study of iridium-coated x-ray mirrors&lt;/title&gt;

Graessle, Dale E.; Burbine, T. H.; Fitch, Jonathan J.; Podgorski, William; Juda, Jiahong Zhang; Elsner, Ronald F.; O’Dell, Stephen L.; Reynolds, John M.

doi:10.1117/12.193173

Cited by 6 publications

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“…We thank Paul Hsieh and John P. Hughes for participating in the bias studies. We are grateful for the 6 cxMltributkIls Cf Mr. Ji B. Sweeney, whose assistance in data acquisitioii and cnputer çerathms maintenance have been invaluable to the ccmp1etii d this work. We appreciate the efforts d MIchael Sagurton cd NSLS/Bectel/Sachs-Freeman Associates fcr his support c our wcMk as X8 beaniline scientist.…”

Section: Acknowledgmentsmentioning

confidence: 99%

<title>Optical constants from synchrotron reflectance measurements of AXAF witness mirrors 2 to 12 keV</title>

Graessle

Burek

Fitch

et al. 1997

Grazing Incidence and Multilayer X-Ray Optical Systems

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We report iridium optical constants fitted from synchrotrxi reflectance data. Specifically, we have used the NKFIT algththin of Di Windt' to derive ö(E) and f(E) frmi 2-12 keV reflectance calibrations of AXAF witness mirrors. The model is applied at each energy separately, to fit four to nine data points fran reflectance-versus-energy scans at selected grazing angles. The stability of the model in the presence c( gaussian noise has been tested extensively. We report the results af several bias studies, involving the generation and analysis c artificial daui Bias studies have been used to determine the optimal grazing angles to be scanned in the various X-ray energy ranges to ccndithm the optical constants. They have also been used to investigate the effects of mthvidual errant data points on the resulting fits and derived optical constants. The results will aid in eliminating systematic errors in the derived optical constants. We also present results af our investigation of the Debye-Wall& and Nevot-Croce3 roughness crrection algorithms as applied to ir measurements. The Nevot-Croce method gives a much better representation atthe data, however its rigrous justification in this experiment is lacking, and the roughness parameter derived is not constant with energy. A more self-consistent model for roughness correction is sought.

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Section: Acknowledgmentsmentioning

confidence: 99%

<title>Optical constants from synchrotron reflectance measurements of AXAF witness mirrors 2 to 12 keV</title>

Graessle

Burek

Fitch

et al. 1997

Grazing Incidence and Multilayer X-Ray Optical Systems

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“…To address these problems, many authors have suggested covering heavy materials with a thin layer of a low-Z material, such as C or B 4 C [14][15][16][17] or even an organic compound (polyethylene 18 ). As shown in Fig.…”

Section: Design Of Grazing Incidence Mirrorsmentioning

confidence: 99%

Comparative study of single-layer, bilayer, and trilayer mirrors with enhanced x-ray reflectance in 0.5- to 8-keV energy region

Yang

Huang

Кожевников

et al. 2020

J. Astron. Telesc. Instrum. Syst.

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Effective area is one of the most important parameters of x-ray telescopes. It can be increased by enlarging the entrance aperture or maximizing the reflectivity through the proper designing and optimization of the reflecting coating. A method to increase the reflectivity of grazing incidence x-ray mirrors in the 0.5-to 8-keV energy region is analyzed. The idea consists in the use of a trilayer reflecting coating instead of single-layer one (e.g., C/Ni/Pt mirror instead of Pt one). Deposition of low-absorbing medium-Z and low-Z layers onto the top of strongly absorbing high-Z material results in essential increase in the reflectivity while keeping the same width of the reflectivity plateau. In particular, C/Ni/Pt trilayer mirror demonstrates enhancement of the double reflection coefficient by a factor achieving 1.5 to 3.5 compared to that of Pt-coated mirror. The effective area of a telescope is also considerably increased. The experimental results are in a very good agreement with the theoretical predictions. In addition, the C/Ni/Pt trilayer mirror exhibits a reasonable thermal stability and a relatively low compressive stress of about −550 MPa. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…From our studies of the effects of contamination on x-ray reflectance 34,35 , we identified a need to verify the transfer of the flux scale from ground calibration to on-orbit performance. Consequently, MSFC Project Science conceived and specified the FCM 37 , a system of 16 radioactive calibration sources to be located on the forward contamination cover (FCC) and measured with the ACIS just prior to opening (permanently) the FCC/sunshade door.…”

Section: Developmentmentioning

confidence: 99%

“…In performing these activities MSFC Project Science worked closely both with scientists from the science-instrument, SAO Mission Support, and Telescope Science teams and with engineers at MSFC and at TRW. Several of the studies addressed requirements on particulate contamination 32,33 and on molecular contamination 34,35 , which were particularly stringent to ensure ≈1% calibration and ground-to-orbit fluxscale transfer. Grazing-incidence optics are much more sensitive to particulate contamination than are normal-incidence optics: The small (0.5°-1° for Chandra) grazing angles result in grains shadowing a mirror surface area many times (of order 100 for Chandra) their own cross-sectional area; hence, the AXAF requirement on dust was about 2 orders of magnitude more severe than the HST requirement.…”

Section: Developmentmentioning

confidence: 99%

The role of project science in the Chandra X-ray Observatory

O’Dell

Weisskopf

2006

SPIE Proceedings

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The Chandra X-ray Observatory, one of NASA's Great Observatories, has an outstanding record of scientific and technical success. This success results from the efforts of a team comprising NASA, its contractors, the Smithsonian Astrophysical Observatory, the instrument groups, and other elements of the scientific community-including the thousands of scientists who utilize this powerful facility for astrophysical research. We discuss the role of NASA Project Science in the formulation, development, calibration, and operation of the Chandra X-ray Observatory. In addition to serving as an interface between the scientific community and the Project, Project Science performed what we term "science systems engineering". This activity encompasses translation of science requirements into technical requirements and assessment of the scientific impact of programmatic and technical trades. We briefly describe several examples of science systems engineering conducted by Chandra Project Science.

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<title>Molecular contamination study of iridium-coated x-ray mirrors</title>

Cited by 6 publications

References 0 publications

<title>Optical constants from synchrotron reflectance measurements of AXAF witness mirrors 2 to 12 keV</title>

<title>Optical constants from synchrotron reflectance measurements of AXAF witness mirrors 2 to 12 keV</title>

Comparative study of single-layer, bilayer, and trilayer mirrors with enhanced x-ray reflectance in 0.5- to 8-keV energy region

The role of project science in the Chandra X-ray Observatory

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