Paper
27 September 2012 Calibration of the eROSITA calibration source: design and trade-off analysis
Michael J. Freyberg, Bernd Budau, Vadim Burwitz, Konrad Dennerl, Gisela Hartner, Andreas von Kienlin, Benedikt Menz, Benjamin Mican
Author Affiliations +
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.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Michael J. Freyberg, Bernd Budau, Vadim Burwitz, Konrad Dennerl, Gisela Hartner, Andreas von Kienlin, Benedikt Menz, and Benjamin Mican "Calibration of the eROSITA calibration source: design and trade-off analysis", Proc. SPIE 8443, Space Telescopes and Instrumentation 2012: Ultraviolet to Gamma Ray, 844351 (27 September 2012); https://doi.org/10.1117/12.927085
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KEYWORDS
Calibration

Aluminum

X-rays

Cameras

Charge-coupled devices

Electrons

Optical filters

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