First qualification and selection of the eROSITA PNCCDs

For the X-ray astronomy instrument eROSITA a framestore PNCCD was developed by the MPI Halbleiterlabor. The PNCCD has an image area of 384×384384×384 pixels with a size of 75μm×75μm. Each channel of the PNCCD has an own readout anode which allows parallel amplification and signal processing of the CCD signals of one row.The first measurements for the spectroscopic characterization of the PNCCDs are made with a special measurement setup—the so-called Cold Chuck Probe Station. The Cold Chuck Probe Station allows to fully operate the CCD without mounting and bonding the chip on a PCB as the CCD is contacted only with needles. Thus all eROSITA PNCCDs can be qualified under the same measurement conditions and with an identical electronic setup. Therefore the results can be compared directly. The spectroscopic properties of the PNCCDs, like the charge transfer efficiency and the energy resolution are measured. Also pixel defects such as bright pixels or non-transferring pixels are detected.With the Cold Chuck Probe Station a readout noise of 2.7 e− ENC can be achieved and reliable measurement results obtained. Based on these results the best PNCCDs will be selected for eROSITA.