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Session 77 - AXAF Calibration.
Display session, Wednesday, January 17
North Banquet Hall, Convention Center

[77.04] Modeling Electron-Impact X-Ray Spectra for the AXAF\/ Calibration

M. E. Sulkanen, R. F. Elsner (NASA/MSFC), J. J. Kolodziejczak (USRA)

The Advanced X-ray Astrophysics Facility (AXAF) will provide high-resolution imaging and spectroscopy of astrophysical x-ray sources. A precision calibration of the AXAF\/ telescope and science instruments will be performed by the AXAF\/ Team, using x-ray sources at NASA's X-Ray Calibration Facility (XRCF), located at Marshall Space Flight Center. A tool to model the spectra from electron-impact x-ray sources for a variety of targets is necessary to predict the detected spectra and count rates for various combinations of telescope-detector calibrations.

We model the spectra of x-ray lines and continuum (0.1 - 13 keV) arising from electron impact on solid targets. We use simple models for electron transport, line and continuum emissivities, and radiative transport through the target. The electrons are attenuated in energy but not scattered in direction. The continuum x-ray emission is modeled as bremsstrahlung, and the characteristic x-ray line emission is modeled as electron-collisional ionization followed by radiative decay to form the lines. X-ray attenuation is included in the radiative transfer, and multilayer or compound targets can be handled. The x-ray spectra produced by this model are compared to those of the Pella et al.\/ model, and experimental data from metal targets.

A WWW catalog is available of the x-ray source spectra for twenty-one targets, with atomic numbers 4 \le Z \le 79, for various target voltages. Also compiled are the x-ray spectra at the telescope focal plane after passage through the AXAF\/ HRMA, and the detected-photon spectra for the ACIS and HRC.

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