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Proceedings Paper

Quantum efficiency measurements of eROSITA pnCCDs
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Paper Abstract

For the eROSITA X-ray telescope, which is planned to be launched in 2012, detectors were developed and fabricated at the MPI Semiconductor Laboratory. The fully depleted, back-illuminated pnCCDs have an ultrathin pn-junction to improve the low-energy X-ray response function and quantum efficiency. The device thickness of 450 μm is fully sensitive to X-ray photons yielding high quantum efficiency of more than 90% at photon energies of 10 keV. An on-chip filter is deposited on top of the entrance window to suppress visible and UV light which would interfere with the X-ray observations. The pnCCD type developed for the eROSITA telescope was characterized in terms of quantum efficiency and spectral response function. The described measurements were performed in 2009 at the synchrotron radiation sources BESSY II and MLS as cooperation between the MPI Semiconductor Laboratory and the Physikalisch-Technische Bundesanstalt (PTB). Quantum efficiency measurements over a wide range of photon energies from 3 eV to 11 keV as well as spectral response measurements are presented. For X-ray energies from 3 keV to 10 keV the quantum efficiency of the CCD including on-chip filter is shown to be above 90% with an attenuation of visible light of more than five orders of magnitude. A detector response model is described and compared to the measurements.

Paper Details

Date Published: 16 July 2010
PDF: 10 pages
Proc. SPIE 7742, High Energy, Optical, and Infrared Detectors for Astronomy IV, 77420U (16 July 2010); doi: 10.1117/12.856939
Show Author Affiliations
Stefanie Ebermayer, Max-Planck-Institut Halbleiterlabor (Germany)
Robert Andritschke, Max-Planck-Institut Halbleiterlabor (Germany)
Johannes Elbs, Max-Planck-Institut Halbleiterlabor (Germany)
Norbert Meidinger, Max-Planck-Institut Halbleiterlabor (Germany)
Lothar Strüder, Max-Planck-Institut Halbleiterlabor (Germany)
Robert Hartmann, Max-Planck-Institut Halbleiterlabor (Germany)
PNSensor GmbH (Germany)
Alexander Gottwald, Physikalisch-Technische Bundesanstalt (Germany)
Michael Krumrey, Physikalisch-Technische Bundesanstalt (Germany)
Frank Scholze, Physikalisch-Technische Bundesanstalt (Germany)

Published in SPIE Proceedings Vol. 7742:
High Energy, Optical, and Infrared Detectors for Astronomy IV
Andrew D. Holland; David A. Dorn, Editor(s)

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