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First characterization of an X-ray detector at BESSY II and MLS


For the first time, an X-ray detector has been completely characterized and calibrated at the PTB-owned Metrology Light Source (MLS) and in the PTB laboratory at BESSY II. For the eROSITA X-ray telescope, a backside illuminated pnCCD detector with a thickness of 450 µm was developed and fabricated at the Max-Planck-Institute Semiconductor Laboratory (MPI HLL). It has an ultrathin pn-junction as entrance window to improve the low-energy X-ray response. An on-chip filter is deposited on top of the entrance window to suppress unwanted visible and UV radiation. Quantum efficiency measurements over a wide range of photon energies from 3 eV to 20 keV as well as spectral response measurements between 100 eV and 11 keV were performed using the VUV beamline at the MLS as well as the four-crystal monochromator beamline, the plane grating monochromator beamline, SX700, and calculable radiation of the dipole white light beamline at BESSY II. For X-ray energies from 3 keV to 10 keV the quantum efficiency of the CCD including on-chip filter was shown to be above 90 % with an attenuation of visible light of more than five orders of magnitude. The eROSITA X-ray telescope will be launched in 2012. 


M. Krumrey , AG 7.11, E-Mail: Michael.Krumrey(at)ptb.de
F. Scholze , AG 7.22 , E-Mail: Frank.Scholze(at)ptb.de
A. Gottwald , AG 7.23 , E-Mail: Alexander.Gottwald(at)ptb.de