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Proceedings Paper

Calibration of the eROSITA calibration source: design and trade-off analysis
Author(s): Michael J. Freyberg; Bernd Budau; Vadim Burwitz; Konrad Dennerl; Gisela Hartner; Andreas von Kienlin; Benedikt Menz; Benjamin Mican
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Paper Abstract

Due to the particle background and radiation damage in orbit, the CCDs aboard X-ray astronomical satellites (such as eROSITA) tend to degrade in their performance, especially in the charge transfer inefficiency (CTI). The on-board Calibration Source based on Fe-55 will be used to monitor the CTI and the gain. It provides Mn-Kα (5.89 keV) and Mn-Kβ (6.49 keV) lines (accompanied by Auger electrons), but also the Al-K (1.49 keV) and Ti-Kα (4.51 keV) and Ti-Kβ (4.93 keV) fluorescence lines from a target made of aluminum and a contribution of titanium. Measurements with the Calibration Source will be used to compare the on-board CTI with the CTI measured on ground and to modify the CTI correction. We summarize the design and trade-off analysis of the internal eROSITA calibration source and present results obtained with TRoPIC (eROSITA prototype camera) at the PANTER X-ray test facility in the energy range 0.5−250 keV. Various geometries have been tested to optimize the homogeneity of the calibration lines in the focal plane, the overall efficiency, and the line ratios between Mn-K and Al-K. Additionally, multi-component target materials (titanium and silver in addition to aluminum) have been tested. Moreover, the required source strength has been determined to obtain enough photons from the source after several years when radiation damage becomes significant and the source intensity has decayed (T1/2 ~ 999 d). Finally, also measurements to determine the electron content have been performed.

Paper Details

Date Published: 27 September 2012
PDF: 11 pages
Proc. SPIE 8443, Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray, 844351 (27 September 2012); doi: 10.1117/12.927085
Show Author Affiliations
Michael J. Freyberg, Max-Planck-Institut für extraterrestrische Physik (Germany)
Bernd Budau, Max-Planck-Institut für extraterrestrische Physik (Germany)
Vadim Burwitz, Max-Planck-Institut für extraterrestrische Physik (Germany)
Konrad Dennerl, Max-Planck-Institut für extraterrestrische Physik (Germany)
Gisela Hartner, Max-Planck-Institut für extraterrestrische Physik (Germany)
Andreas von Kienlin, Max-Planck-Institut für extraterrestrische Physik (Germany)
Benedikt Menz, Max-Planck-Institut für extraterrestrische Physik (Germany)
Benjamin Mican, Max-Planck-Institut für extraterrestrische Physik (Germany)

Published in SPIE Proceedings Vol. 8443:
Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray
Tadayuki Takahashi; Stephen S. Murray; Jan-Willem A. den Herder, Editor(s)

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