Radiation hardness of pn-CCDs for X-ray astronomy

Results of all extensive radiation hardness test of a full depletion pn-Charge Coupled Device (pn-CCD) detector are presented. The pn-CCD is a new type of Charge Coupled Device designed for X-ray spectroscopy in ESA's cornerstone X-ray Multi Mirror (XMM) satellite mission. The devices were irradiated with 10 MeV-protons with fluences up to 6.5/spl middot/10/sup 9/ cm/sup -2/. This is more than one order of magnitude higher than the equivalent proton radiation environment expected for the 10 year mission. The only effect to the device was a degradation of charge transfer efficiency (CTE) at temperatures around 120 K. At XMM's operating temperature between 140 K and 170 K the performance of the detector will not significantly change during the 10 year mission. The degradation of the CTE was studied, and a method to improve it is described.