The silicon lattice defects in proton and gamma irradiated n-channel CCDs

The Charge Coupled Device (CCD) has often been the imaging detector of choice for satellite missions. The space environments these camera systems operate in is abundant with highly energetic radiation. It is impossible to fully protect the CCD from the radiation environment, understanding the impact of radiation damage at a fundamental level is essential to characterise and correct the degradation on the image or spectrum. Here we study the properties of individual traps, with particular attention paid to the silicon divacancy, one of the major trap species found in n-channel CCDs caused by radiation damage that can effect image readout. Through the use of the trap pumping technique it is possible to observe individual traps and their properties in high detail with sub-pixel accuracy. Previous studies using the trap pumping technique have focused on proton irradiated CCDs to characterise the resulting defects. In addition to proton irradiated devices, the use of a ⁶⁰Co source allows the study of traps resulting from gamma irradiation and through this analysis a comparison can be made.