Data analysis for characterizing PNCCDS

The Max-Planck-Institute semiconductor lab develops, fabricates, tests, and qualifies pnCCDs for space and ground based applications. pnCCDs are CCDs showing high quantum efficiency up to 20 keV while delivering good spatial and energy resolution. This article describes the algorithms applied to the raw data as recorded by the data acquisition system. The main purpose of the underlying software is to qualify the individual pnCCD by measurements of monoenergetic X-ray lines, from B-K (183 eV) to Mo-Kα (17.5 keV), typically Mn-Kα (5.9 keV) under various conditions (e.g. temperature, readout speed, electrical supply voltages of the detector and electronics). Therefore characteristic parameters are determined individually for each measurement as there are read noise, gains, charge transfer efficiencies, charge splitting between neighboring pixels, energy resolution, and bad pixels while correcting for offsets, gains, charge transfer inefficiencies, non-linearities of the electronics, and while recombining the charges spread over more than one pixel. These figures are used in three ways: Firstly, operating parameters are optimized by comparing individual measurements. Secondly, the individual device is rated by combining the results of all its measurements. Thus devices can be selected for applications such as measurement setups for DESY, FLASH, or the X-ray test facility PANTER. Especially the flight modules for the X-ray astronomy mission eROSITIA will be chosen based on the key figures. Thirdly, improvements gained from detector and electronics design and production modifications are quantified closing the development loop of pnCCDs and their associated electronics.