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Composition of the Chandra ACIS ContaminantThe Advanced CCD Imaging Spectrometer (ACIS) on the Chandra X-ray Observatory is suffering a gradual loss of low energy sensitivity due to a buildup of a contaminant. High resolution spectra of bright astrophysical sources using the Chandra Low Energy Transmission Grating Spectrometer (LETGS) have been analyzed in order to determine the nature of the contaminant by measuring the absorption edges. The dominant element in the contaminant is carbon. Edges due to oxygen and fluorine are also detectable. We can place stringent limits on nitrogen and high Z elements such as AI, Si, and Mg. Not including H, we find that C, O, and F comprise less than 80%, 7%, and 7% of the contaminant by number, respectively, Nitrogen is less than 3% of the contaminant. We will assess various candidates for the contaminating material and the time dependence. For example, the detailed structure of the absorption edges provides information about the bonding structure of the compound, eliminating aromatic hydrocarbons as the contaminating material.
Document ID
20030068114
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
Marshall, Herman
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Tennant, Allyn
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Grant, Catherine
(Massachusetts Inst. of Tech. Cambridge, MA, United States)
Hitchcock, Adam
(McMaster Univ. Hamilton, Ontario, Canada)
ODell, Steve
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Plucinsky, Paul
(Harvard Univ. Cambridge, MA, United States)
Date Acquired
August 21, 2013
Publication Date
January 1, 2003
Subject Category
Instrumentation And Photography
Meeting Information
Meeting: X-Ray and Gamma-Ray Instrumentation for Astronomy XIII
Location: San Diego, CA
Country: United States
Start Date: August 3, 2003
End Date: August 8, 2003
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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